JP7632497B2 - Diagnostic device and program - Google Patents

Description

The present invention relates to a diagnostic device and program for diagnosing power switch ON failures.

Conventionally, in a power supply system including a power supply, an inverter, and a rotating electric machine, a power supply switch (system main relay) that connects or disconnects the power supply and the rotating electric machine is provided in a power supply path that connects the power supply and the inverter. In addition, in this power supply system, a device is known that diagnoses whether the power supply switch is welded while the rotating electric machine is being rotated.

For example, in Patent Document 1, when a power supply abnormality is detected, a cutoff command is output to cut off the power switch, and the inverter is controlled so that the path voltage, which is the voltage of the power supply path on the inverter side of the power switch, becomes a predetermined target voltage, and welding of the power switch is diagnosed based on whether or not this control causes the path voltage to change to the target voltage.

JP 2009-183134 A

When a rotating electric machine is rotating, a back electromotive force is generated according to the rotation speed of the rotating electric machine. Therefore, in order to control the inverter to set the path voltage to a target voltage, it is necessary to control the inverter so as to cancel the back electromotive force of the rotating electric machine, which complicates the configuration and control of the inverter. There is a demand for technology that can properly diagnose power switch on failures without changing the path voltage through inverter control.

The present invention has been made to solve the above problems, and its purpose is to provide a diagnostic device and program that can properly diagnose power switch ON failures.

The first means for solving the above problem is applied to a power supply system including a power supply, an inverter connected to the power supply, a rotating electric machine connected to the inverter, a power switch provided in a power supply path between the power supply and the inverter, and a voltage sensor that detects a path voltage, which is the voltage of the power supply path on the inverter side of the power switch, and includes a shutoff command unit that outputs a shutoff command to shut off the power supply switch while stopping control of the inverter when a predetermined switch diagnosis condition is satisfied in the conductive state of the power switch, an acquisition unit that acquires a voltage difference that is the difference in the detected voltage of the voltage sensor according to the change in the rotation speed of the rotating electric machine after the shutoff command unit outputs the shutoff command, and a diagnosis unit that diagnoses an on-failure of the power supply switch based on the voltage difference.

In the above configuration, when a predetermined switch diagnosis condition is satisfied in the conductive state of the power switch, a shutoff command is output to shut off the power switch with the inverter control stopped. In addition, a voltage difference, which is the difference between the detected voltages of the voltage sensors according to the change in the rotation speed of the rotating electric machine that occurs after the shutoff command is output, is obtained, and an ON failure of the power switch is diagnosed based on the voltage difference. Here, when the power switch is normal, in the inverter control stopped state, the path voltage on the inverter side after the shutoff command is output (the voltage of the power path on the inverter side of the power switch) depends on the back electromotive force of the rotating electric machine, and when the rotation speed of the rotating electric machine changes after the shutoff command is output, it changes corresponding to the change in the rotation speed. On the other hand, when the power switch has an ON failure, the path voltage on the inverter side after the shutoff command is output does not change corresponding to the change in the rotation speed even if the rotation speed of the rotating electric machine changes after the shutoff command is output. Therefore, by grasping the voltage change corresponding to the change in the rotation speed of the rotating electric machine that occurs after the shutoff command is output, the ON failure of the power switch can be appropriately diagnosed. In addition, the above configuration diagnoses the power switch for an ON failure while inverter control is stopped, making it possible to realize switch failure diagnosis with a simple configuration without causing voltage changes due to inverter control.

In the second means, in the power supply system, a smoothing capacitor is connected in parallel to the power supply in the power supply path on the inverter side of the power switch, and a discharge processing unit is provided that discharges the smoothing capacitor in a situation in which the rotation speed decreases after the shutoff command is output by the shutoff command unit, and the acquisition unit acquires, as the voltage difference, the difference between the detected voltage before the smoothing capacitor is discharged by the discharge processing unit and the detected voltage after the smoothing capacitor is discharged in a situation in which the rotation speed decreases after the shutoff command is output.

By providing a smoothing capacitor in the power supply system, the path voltage can be stabilized. On the other hand, providing a smoothing capacitor in the power supply system may hinder monitoring of voltage changes on the inverter side. In this regard, in the above configuration, the smoothing capacitor is discharged in a situation where a drop in the rotation speed of the rotating electric machine occurs after the output of a cutoff command. As a result, after the cutoff command is output, the path voltage on the inverter side can be set to a voltage that corresponds to the rotation speed of the rotating electric machine, and an on-failure of the power switch can be properly diagnosed.

In the third method, the discharge processing unit discharges the smoothing capacitor so that the path voltage is lower than the electromotive force voltage of the rotating electric machine when the discharge of the smoothing capacitor is completed.

When the smoothing capacitor finishes discharging, the route voltage is recharged to the electromotive force voltage of the rotating electric machine. In this case, if the route voltage at the end of the smoothing capacitor's discharge is higher than the electromotive force voltage of the rotating electric machine, it becomes impossible to grasp the voltage change corresponding to the change in the rotation speed of the rotating electric machine. In this regard, the smoothing capacitor is discharged so that the route voltage is lower than the electromotive force voltage of the rotating electric machine at the end of the smoothing capacitor's discharge. This makes it possible to properly grasp the voltage change corresponding to the change in the rotation speed of the rotating electric machine, and thus to properly perform a fault diagnosis of the power switch.

In the fourth means, the discharge processing unit enables the smoothing capacitor to be discharged multiple times under circumstances where a decrease in the rotation speed occurs after the output of the shutoff command, and the acquisition unit acquires the rotation speed and the path voltage before the first discharge of the smoothing capacitor and after each subsequent discharge when the smoothing capacitor is discharged multiple times, and the diagnosis unit calculates an approximation line that linearly approximates the relationship between the rotation speed and the path voltage using three or more combinations of the rotation speed and the path voltage acquired by the acquisition unit, and diagnoses an on-failure of the power switch based on the slope of the approximation line and the variation of the path voltage relative to the approximation line.

For example, even if the power switch has an on-failure, the path voltage may change due to detection error or noise from the voltage sensor. In this case, the voltage difference may become large, and there is a concern that the on-failure of the power switch may be missed. In this regard, in the above configuration, in a situation where the rotation speed of the rotating electric machine decreases after the output of a power switch cut-off command, the smoothing capacitor is discharged multiple times, and an approximation line is calculated from the rotation speed and path voltage obtained for each capacitor discharge. In addition, the on-failure of the power switch is diagnosed based on the slope of the approximation line and the variation in the path voltage relative to the approximation line. In this case, the reliability of the slope of the approximation line can be determined based on the variation in the path voltage relative to the approximation line, and the on-failure diagnosis of the power switch can be performed appropriately using the slope of the approximation line.

In the fifth means, in a situation where a decrease in the rotation speed occurs after the output of the shutoff command, the acquisition unit acquires the rotation speed and the path voltage before and after the first capacitor discharge by the discharge processing unit as first data and second data, respectively, and acquires the rotation speed and the path voltage after the subsequent second capacitor discharge as third data. If the rotation speed of the rotating electric machine is higher than a predetermined value when the second data is acquired, the diagnosis unit acquires the first to third data and diagnoses an ON failure of the power switch using the first to third data, while if the rotation speed of the rotating electric machine is lower than the predetermined value when the second data is acquired, the diagnosis unit acquires the first and second data of the first to third data and diagnoses an ON failure of the power switch using the first and second data.

When discharging the smoothing capacitor multiple times and diagnosing a power switch ON fault based on an approximate straight line calculated from the rotation speed and path voltage for each capacitor discharge and the variation in the path voltage relative to the approximate straight line, it is possible to improve the accuracy of the fault diagnosis, but there is a concern that the fault diagnosis will take time because multiple capacitor discharges are required. In addition, if the rotating electric machine is in a low rotation state, it may be impossible to predict a change in the rotation speed from that point on.

In this regard, if the rotation speed of the rotating electric machine is higher than a predetermined value when the second data is acquired after the first capacitor discharge, the first to third data are used to diagnose an ON failure of the power switch, whereas if the rotation speed of the rotating electric machine is lower than a predetermined value when the second data is acquired, the first and second data are used to diagnose an ON failure of the power switch. This allows for proper failure diagnosis to be performed while taking into account the rotation state of the rotating electric machine.

In the sixth means, the power supply system includes a current sensor that detects the power supply current, which is the current flowing through the power supply, and the acquisition unit acquires the detected current of the current sensor after the shutoff command is output by the shutoff command unit, and the diagnosis unit executes a first determination process to determine whether the voltage difference is greater than a predetermined voltage threshold and a second determination process to determine whether the detected current is greater than a predetermined current threshold, and diagnoses the power switch as having an on-failure when the first determination process determines that the voltage difference is less than the voltage threshold and the second determination process determines that the detected current is greater than the current threshold.

According to the above configuration, a first judgment process using the voltage difference and a second judgment process using the detected current are executed, and if the first judgment process judges that the voltage difference is smaller than a predetermined voltage threshold and the second judgment process judges that the detected current is larger than a current threshold, the power switch is diagnosed as having an on-failure. By diagnosing the on-failure of the power switch using the voltage difference and the detected current, the on-failure diagnosis of the power switch can be performed more appropriately than when the on-failure of the power switch is diagnosed using only the voltage value.

In the seventh aspect, the power supply system is mounted on a vehicle capable of rotating the rotating electric machine in response to the rotation of the wheels, and includes a speed control unit that reduces the vehicle's traveling speed to reduce the rotational speed of the rotating electric machine when the shutoff command is output by the shutoff command unit, and releases the reduced traveling speed when the diagnostic unit determines that the power switch is normal.

With the above configuration, the rotation speed of the rotating electric machine decreases as the vehicle speed decreases, so that the desired voltage drop can be generated on the inverter side. In addition, the vehicle's running speed can be appropriately controlled each time depending on whether the power switch is normal or has an on-failure.

In the eighth means, the power supply system is mounted on a vehicle equipped with a gear mechanism that changes the gear ratio in a rotation transmission path between the wheels and the rotating electric machine, and includes a gear ratio adjustment unit that increases the gear ratio of the rotating electric machine side relative to the wheel side while the vehicle is traveling after the shutoff command is output by the shutoff command unit, and the acquisition unit acquires, as the voltage difference, the difference between the detected voltage before the gear ratio is increased by the gear ratio adjustment unit and the detected voltage after the gear ratio is increased.

In the above configuration, after the cutoff command is output, the gear ratio of the rotating electric machine to the wheel side is increased. This makes it possible to reduce the rotation speed of the rotating electric machine while suppressing the decrease in vehicle speed, making it less likely that a sense of discomfort caused by deceleration will occur while the vehicle is traveling.

In the ninth aspect, the power supply system rotates the propeller using the rotating electric machine in an aircraft that flies in accordance with the rotation of the propeller, and includes a propeller rotation control unit that reduces the rotation speed of the rotating electric machine along with the rotation speed of the propeller when the cutoff command is output by the cutoff command unit.

With the above configuration, in the aircraft, the rotation speed of the rotating electric machine decreases along with the decrease in the propeller rotation speed, thereby generating the desired voltage drop required for fault diagnosis of the power switch on the inverter side.

In the tenth means, the propeller rotation control unit releases the reduced propeller rotation speed state when, after the shutoff command is output and the diagnosis unit performs a diagnosis, it is determined that the power switch is normal and there is a request to increase the propeller rotation speed.

According to the above configuration, when the power switch is determined to be normal and there is a request to increase the propeller rotation speed, the reduced propeller rotation speed state is released, so that after the power switch fault diagnosis, the flight of the aircraft can be suitably restored to the flight state before the diagnosis.

In an eleventh aspect, the power supply system is applied to a moving body having a plurality of drive units each having the inverter, the rotating electric machine, the power switch, and the voltage sensor, and the moving body is capable of moving by driving some of the drive units, and when some of the drive units in a driven state are to be stopped while the moving body is moving, the cutoff command unit determines that the switch diagnosis condition is satisfied for the drive unit to be stopped, and outputs the cutoff command.

In the above configuration, when some of the drive units are stopped from a driven state while a moving body having multiple drive units is moving, it is determined that the switch diagnosis condition is satisfied for the drive unit to be stopped, and a shutoff command is output. In this case, a fault diagnosis can be performed on the drive unit in the stopped state without affecting the moving status of the moving body.

The twelfth means includes a power control unit that, when some of the drive units are stopped while the moving body is moving and the cutoff command is output by the cutoff command unit for the drive units to be stopped, outputs a power command value for maintaining the moving state of the moving body to the other drive units to which the cutoff command has not been output.

According to the above configuration, when the drive of any of the multiple drive units is stopped to perform a fault diagnosis of the power switch, the moving state of the moving body is maintained without change before and after the drive is stopped. This allows fault diagnosis of the drive unit to be performed without affecting the moving state of the moving body.

FIG. 1 is a diagram showing the configuration of a control system. 11 is a flowchart showing the procedure of a control process. 5 is a flowchart showing a processing procedure of a diagnosis process according to the first embodiment. This is a timing chart when the main relay is normal. This is a timing chart when the main relay has an on-fault. Graph showing the slope of the path voltage. 10 is a flowchart showing a processing procedure of a diagnosis process according to a second embodiment. 13 is a flowchart showing a processing procedure of a diagnosis process according to the third embodiment. This is a timing chart when the main relay is normal. This is a timing chart when the main relay has an on-fault. Graph showing an approximation line. FIG. 13 is a configuration diagram of a control system according to a fourth embodiment. 13 is a flowchart showing a processing procedure of a diagnosis process according to the fourth embodiment. 13 is a flowchart showing a processing procedure of a diagnosis process according to the fourth embodiment. 10 is a flowchart showing a procedure of a diagnostic process according to another embodiment.

First Embodiment
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which a diagnostic device according to the present invention is applied to an on-vehicle control system 10 will be described below with reference to the drawings.

As shown in FIG. 1, the control system 10 is a control system for a hybrid vehicle having an engine 31 and a rotating electric machine 21 as a driving power source. This control system 10 corresponds to a power supply system. The output shaft 32 of the engine 31 is connected to the rotating shaft 22 of the rotating electric machine 21 via a transmission 33. The rotating shaft 22 of the rotating electric machine 21 is connected to an axle 51 that connects the left and right wheels 50 of the vehicle via a well-known gear mechanism 34. The driving force of the engine 31 and the rotating electric machine 21 is transmitted to the wheels 50 via the gear mechanism 34, and the wheels 50 rotate. In addition, the rotating electric machine 21 rotates in accordance with the rotation of the wheels 50, and the rotating electric machine 21 generates electricity. The electricity generated by the rotating electric machine 21 is stored in the battery 23, which is a power source.

The battery 23 is connected to the rotating electric machine 21 via the inverter 24, and inputs and outputs power between the rotating electric machine 21. The battery 23 is, for example, a lithium-ion storage battery. The rotating electric machine 21 is a three-phase synchronous machine, and has U-, V-, and W-phase windings as stator windings. The rotating electric machine 21 is, for example, a permanent magnet synchronous machine.

The inverter 24 has three phases of upper arm switches QUH, QVH, and QWH and lower arm switches QUL, QVL, and QWL connected in series. In this embodiment, a voltage-controlled semiconductor switching element, specifically an IGBT, is used as each switch. A freewheel diode DA is connected in inverse parallel to each switch.

In each series connection, the connection point between the low potential side terminal of the upper arm switch QUH, QVH, QWH and the high potential side terminal of the lower arm switch QUL, QVL, QWL is connected to the corresponding winding of the rotating electric machine 21 via a conductive member 25 such as a bus bar. In addition, the high potential side terminal of each upper arm switch QUH, QVH, QWH is connected to the positive terminal of the battery 23 by a positive side power supply path LP. The low potential side terminal of each lower arm switch QUL, QVL, QWL is connected to the negative terminal of the battery 23 by a negative side power supply path LN.

The control system 10 includes a smoothing capacitor 26. The smoothing capacitor 26 is connected between the positive power supply path LP and the negative power supply path LN, and is connected in parallel to the battery 23.

The control system 10 includes a first main relay RM1 and a second main relay RM2 as power switches. The first main relay RM1 is provided on the positive power path LP, closer to the battery 23 than the smoothing capacitor 26. The second main relay RM2 is provided on the negative power path LN, closer to the battery 23 than the smoothing capacitor 26. The first and second main relays RM1 and RM2 switch between a conducting state and a non-conducting state between the battery 23 and the rotating electric machine 21.

A series connection of a precharge relay RP and a resistor RA is connected in parallel to the first main relay RM1. When the precharge relay RP is turned on (closed) at the start of current flow between the battery 23 and the rotating electric machine 21, current is passed through the resistor RA, thereby suppressing the flow of inrush current between the battery 23 and the rotating electric machine 21. Note that the precharge relay RP and the resistor RA may be provided on the negative electrode side instead of the positive electrode side, or the precharge relay RP and the resistor RA may not be provided on either the positive electrode side or the negative electrode side. In this embodiment, mechanical relay switches are used as the relays RM1, RM2, and RP.

The control system 10 includes a voltage sensor 27, a current sensor 28, a rotation speed sensor 29, and a vehicle speed sensor 30. The voltage sensor 27 is connected between the positive power path LP and the negative power path LN on the inverter 24 side of the main relays RM1 and RM2, and detects the path voltage VA, which is the voltage between the positive power path LP and the negative power path LN, that is, the voltage applied to the smoothing capacitor 26. The current sensor 28 is provided on the positive power path LP on the battery 23 side of the first main relay RM1, and detects the power current IA, which is the current flowing to the battery 23. The rotation speed sensor 29 detects the rotation speed NA per unit time of the rotating electric machine 21, that is, the rotation speed. The vehicle speed sensor 30 detects the rotation speed of the wheels 50, that is, the vehicle speed XA, which is the traveling speed of the host vehicle. The detection values of each of these sensors are input to a control device 40 provided in the control system 10.

The functions provided by the control device 40 as a diagnostic device can be provided by software recorded in a physical memory device and a computer that executes the software, by software alone, by hardware alone, or by a combination of these. For example, when the control device 40 is provided by an electronic circuit that is hardware, it can be provided by a digital circuit including a large number of logic circuits, or an analog circuit. For example, the control device 40 executes a program stored in a non-transitory tangible storage medium that serves as a storage unit that the control device 40 has. By executing the program, a method corresponding to the program is performed. The storage unit is, for example, a non-volatile memory. Note that the program stored in the storage unit can be updated, for example, via a network such as the Internet.

The control device 40 acquires each detection value and performs various controls based on the acquired values. Specifically, the control device 40 controls the inverter 24 based on each detection value and controls the open/closed state of each relay RM1, RM2, and RP.

The control device 40 also diagnoses the main relays RM1 and RM2 for failure when a specified switch diagnosis condition is met. For example, if an abnormality occurs in the battery 23 or inverter 24 while the vehicle is running, causing an overcurrent to flow through the power supply paths LP and LN, the control device 40 diagnoses the main relays RM1 and RM2 for failure.

In this embodiment, when the main relays RM1, RM2 are in a closed state (conducting state) and it is determined that an abnormality (hereinafter, a specific abnormality) has occurred in a device connected to the main relays RM1, RM2, such as the battery 23 or the inverter 24, the switch diagnosis condition is deemed to be satisfied, and a shutoff command is output to shut off the main relays RM1, RM2 with the control of the inverter 24 stopped. In addition, a voltage difference ΔV, which is the difference in the path voltage VA according to the change in the rotation speed NA of the rotating electric machine 21 that occurs after the shutoff command is output, is obtained, for example, in a situation where the rotation speed NA of the rotating electric machine 21 changes after the output of the shutoff command, and an ON failure of the main relays RM1, RM2 is diagnosed based on the voltage difference ΔV.

Figure 2 shows a flowchart of the control process of this embodiment. The control device 40 repeatedly executes the control process at a predetermined interval while the vehicle is traveling.

When the control process is started, in step S11, it is determined whether or not a specific abnormality has occurred. The control device 40 determines whether or not a specific abnormality has occurred based on, for example, the detection value of the current sensor 28. If a specific abnormality has not occurred, the process proceeds to step S12, and the vehicle is driven normally. Normal driving refers to the vehicle being driven by the driving force of at least one of the engine 31 and the rotating electric machine 21. On the other hand, if a specific abnormality has occurred, the process proceeds to step S13.

In step S13, control of the inverter 24 is stopped in order to cut off the main relays RM1 and RM2 with the current flowing through them set to zero. In the following step S14, a cut-off command is output to cut off the main relays RM1 and RM2. In the vehicle, as a result of the inverter control being stopped, running using the rotating electric machine 21 is prohibited and running using engine driving force is performed. In this embodiment, the process of step S14 corresponds to the "cut-off command unit, cut-off command step."

In step S15, a diagnostic process is performed to determine whether or not the main relays RM1 and RM2 have an on-failure. The procedure for the diagnostic process is shown in FIG. 3.

In step S21, the driving force of the engine 31 is reduced. This reduction in engine driving force reduces the vehicle speed XA and the rotation speed NA of the rotating electric machine 21. When limiting the driving force of the engine 31 is started, it is preferable to notify the driver of this in order to prevent the driver from feeling uncomfortable due to the deceleration of the vehicle.

In step S22, the path voltage (detected voltage) VA and the rotation speed NA are acquired. In step S22, after the path voltage VA becomes stable after the cutoff command is output, the path voltage VA and the rotation speed NA are acquired. Hereinafter, the path voltage VA and the rotation speed NA acquired in step S22 are referred to as the first voltage V1 and the first rotation speed N1.

In step S23, the vehicle speed XA is acquired, and it is determined whether the vehicle speed XA is equal to or lower than a predetermined speed Xth. The predetermined speed Xth is a vehicle speed at which the smoothing capacitor 26 can be discharged by the rotating electric machine 21 while the rotating electric machine 21 is rotating. When the smoothing capacitor 26 is discharged by the rotating electric machine 21, the inverter 24 controls the smoothing capacitor 26 to pass current to the rotating electric machine 21 at a phase in which no torque is generated in the rotating electric machine 21 even if current is passed through the rotating electric machine 21 while the rotating electric machine 21 is rotating. The predetermined speed Xth is set to a vehicle speed corresponding to a predetermined rotation speed Nth, which is the maximum value at which the path voltage VA can be reduced by suppressing the occurrence of vibrations of the rotating electric machine 21 caused by the back electromotive force of the rotating electric machine 21, even if the smoothing capacitor 26 is discharged by the rotating electric machine 21 while the rotating electric machine 21 is rotating. If the vehicle speed XA is greater than the predetermined speed Xth, step S23 is repeated.

On the other hand, if the vehicle speed XA is equal to or lower than the predetermined speed Xth, the process proceeds to step S24, where the smoothing capacitor 26 is discharged for a predetermined period while the rotating electric machine 21 is rotating. At this time, the smoothing capacitor 26 is discharged for a period longer than the period required for the path voltage VA to decrease to the electromotive force voltage due to the back electromotive force of the rotating electric machine 21 (hereinafter, the back electromotive voltage). This discharge causes the path voltage VA to decrease below the back electromotive voltage of the rotating electric machine 21. In this embodiment, the process of step S24 corresponds to a "discharge processing unit."

In step S25, the path voltage VA and rotation speed NA are acquired after the smoothing capacitor 26 is discharged. At this time, the path voltage VA is acquired in a state where the transient voltage change has converged. In step S25, the second voltage V2 and the second rotation speed N2 are acquired at a timing when the difference between the first rotation speed N1 and the second rotation speed N2 becomes equal to or greater than a predetermined change amount. Hereinafter, the path voltage VA and the rotation speed NA acquired in step S25 are referred to as the second voltage V2 and the second rotation speed N2.

In step S26, the difference between the first rotation speed N1 and the second rotation speed N2 is calculated as the change amount ΔN of the rotation speed NA. In addition, in step S26, the difference between the first voltage V1 and the second voltage V2 is calculated as the voltage difference ΔV of the path voltage VA before and after the change amount ΔN. The first voltage V1 is the path voltage VA before the discharge of the smoothing capacitor 26, and the second voltage V2 is the path voltage VA after the discharge of the smoothing capacitor 26. Therefore, the voltage difference ΔV can be said to be the voltage difference of the path voltage VA before and after the discharge of the smoothing capacitor 26. In this embodiment, the processes of steps S22, S25, and S26 correspond to the "acquisition unit, acquisition step".

In step S27, the slope KA of the change in the path voltage VA before and after the change in the rotation speed NA is calculated. The slope KA is the ratio of the voltage difference ΔV of the path voltage VA to the amount of change ΔN in the rotation speed NA, and is expressed as the following (Equation 1) using the detection values V1, V2, N1, and N2.

KA=ΔV/ΔN=(V2-V1)/(N2-N1) (Equation 1)
In step S28, it is determined whether the slope KA calculated in step S27 is equal to or greater than a predetermined slope threshold Kth. If the slope KA is equal to or greater than the slope threshold Kth, the process proceeds to step S29, where the main relays RM1, RM2 are diagnosed as normal. In this case, in step S30, the restriction on the driving force of the engine 31 is lifted to release the reduced state of the vehicle speed XA, and this process is temporarily terminated. In this embodiment, the process of step S28 corresponds to the "diagnosis unit, diagnosis step", and the processes of steps S21 and S30 correspond to the "speed control unit".

On the other hand, if the slope KA is less than the slope threshold Kth, the process proceeds to step S31, where the main relays RM1 and RM2 are diagnosed as having an ON fault. In this case, the process is temporarily terminated while maintaining the limit on the driving force of the engine 31.

Returning to FIG. 2, in step S16, it is determined whether the main relays RM1 and RM2 have been diagnosed as having an ON-failure in the diagnosis process of step S15. If the main relays RM1 and RM2 have been diagnosed as having an ON-failure, the process proceeds to step S17, where the engine 31 is stopped to prohibit the vehicle from traveling, and this process ends temporarily. On the other hand, if the main relays RM1 and RM2 are diagnosed as normal, the process proceeds to step S18, where the vehicle continues to travel using the engine 31, and this process ends temporarily. Note that in this embodiment, the diagnosis process is performed on the condition that a specific abnormality has occurred, and even if the main relays RM1 and RM2 are diagnosed as normal in step S16, the prohibition on traveling using the rotating electric machine 21 is maintained.

Next, the procedure of the diagnostic process will be described with reference to Figures 4 and 5. In Figures 4 and 5, (A) shows the transition of the control state of the inverter 24, (B) shows the transition of the cutoff command for the main relays RM1 and RM2, (C) shows the transition of the driving force limit of the engine 31, and (D) shows the transition of the vehicle speed XA. In addition, (E) shows the transition of the rotation speed NA, (F) shows the transition of the discharge of the smoothing capacitor 26, and (G) shows the transition of the path voltage VA.

As shown in FIG. 4, before time t1, vehicle speed XA is equal to or greater than a predetermined speed Xth. In addition, main relays RM1 and RM2 are closed, and the inverter 24 controls the rotation speed NA to be equal to or greater than a predetermined rotation speed Nth. Then, at time t1, it is determined that a specific abnormality has occurred, and control of the inverter 24 is stopped. After that, at time t2, a shutoff command is output to shut off main relays RM1 and RM2. In FIG. 4, main relays RM1 and RM2 are assumed to be normal, and the output of the shutoff command opens main relays RM1 and RM2, causing the path voltage VA to change from the power supply voltage VB of the battery 23 to a back electromotive voltage.

When the shutoff command is output, the driving force of the engine 31 is limited at time t3 in order to reduce the rotation speed NA of the rotating electric machine 21. When there is concern that the main relays RM1, RM2 may be turned on due to the occurrence of a specific abnormality, the driving force of the engine 31 is limited and the vehicle speed XA is reduced to ensure the safety of the vehicle. In addition, the first voltage V1 and the first rotation speed N1 are acquired at time t3. Note that the first voltage V1 is acquired after the path voltage VA has stabilized after the shutoff command is output.

When the driving force of the engine 31 is limited at time t3, the rotation speed NA decreases as the vehicle speed XA decreases. When the rotation speed NA decreases, the back electromotive force decreases, but the route voltage VA is kept approximately constant by the smoothing capacitor 26.

When the rotation speed NA drops to a predetermined rotation speed Nth at time t4, the smoothing capacitor 26 is discharged for a predetermined period from time t4 to t5. As a result, the route voltage VA drops to a voltage lower than the back electromotive force of the rotating electric machine 21. When the discharge of the smoothing capacitor 26 is stopped at time t5, the route voltage VA rises due to the back electromotive force of the rotating electric machine 21. When the route voltage VA rises to the back electromotive force of the rotating electric machine 21 at time t6, the second voltage V2 and the second rotation speed N2 are acquired. The second voltage V2 is acquired after the route voltage VA becomes stable after it has risen to the back electromotive force.

When the second voltage V2 and the second rotation speed N2 are acquired, the slope KA of the path voltage VA is calculated using the respective detection values V1, V2, N1, and N2. In the example shown in FIG. 4, the second voltage V2 is lower than the first voltage V1 as the second rotation speed N2 is lower than the first rotation speed N1. Therefore, as shown in FIG. 6(A), the slope KA is equal to or greater than the slope threshold value Kth. As a result, the main relays RM1 and RM2 are diagnosed as normal, and the driving force limit of the engine 31 is released at time t7, and the vehicle continues to run using the engine 31. As a result, the vehicle speed XA increases, and the vehicle resumes running.

On the other hand, FIG. 5 shows the transition of each value when the main relays RM1 and RM2 have an on-failure. In this case, even if a cutoff command is output, the main relays RM1 and RM2 are maintained in the closed state, and the route voltage VA is maintained at the power supply voltage VB of the battery 23. Also, when the discharge of the smoothing capacitor 26 is stopped at time t6, the route voltage VA rises to the power supply voltage VB. Therefore, in the example shown in FIG. 5, the second voltage V2 becomes approximately the same value as the first voltage V1, and as shown in FIG. 6(B), the slope KA becomes smaller than the slope threshold value Kth. As a result, the main relays RM1 and RM2 are diagnosed as having an on-failure, and the vehicle is prohibited from traveling by the engine 31 at time t7 while the driving force limit of the engine 31 is maintained. Specifically, the driving of the engine 31 is stopped at time t7, and the vehicle is stopped from traveling at time t8.

The present embodiment described above provides the following advantages:

In this embodiment, when an abnormality occurs in the battery 23, the inverter 24, or the like while the main relays RM1 and RM2 are in a closed state, a shutoff command is output to shut off the main relays RM1 and RM2 with the control of the inverter 24 stopped. In addition, a voltage difference ΔV, which is the difference in the path voltage VA according to the change in the rotation speed NA of the rotating electric machine 21 that occurs after the shutoff command is output, is obtained, and an ON failure of the main relays RM1 and RM2 is diagnosed based on the voltage difference ΔV. This makes it possible to appropriately diagnose the ON failure of the main relays RM1 and RM2. In addition, in this embodiment, the ON failure of the main relays RM1 and RM2 is diagnosed with the control of the inverter 24 stopped, and a switch failure diagnosis can be realized with a simple configuration without causing a voltage change due to inverter control.

In this embodiment, the smoothing capacitor 26 is discharged in a situation where the rotation speed NA of the rotating electric machine 21 decreases after the output of the cutoff command. This allows the path voltage VA to be a voltage corresponding to the rotation speed NA of the rotating electric machine 21 after the cutoff command is output, and allows the on-failure of the main relays RM1 and RM2 to be properly diagnosed.

In this embodiment, the smoothing capacitor 26 is discharged so that the path voltage VA is lower than the back electromotive voltage of the rotating electric machine 21 when the smoothing capacitor 26 finishes discharging. This makes it possible to properly grasp the voltage change corresponding to the change in the rotation speed NA of the rotating electric machine 21, and thus to properly perform a fault diagnosis of the main relays RM1 and RM2.

In this embodiment, when the vehicle speed XA is equal to or lower than a predetermined speed Xth, the rotating electric machine 21 is caused to discharge the smoothing capacitor 26. Therefore, even if the rotating electric machine 21 discharges the smoothing capacitor 26 while the rotating electric machine 21 is rotating, it is possible to prevent the rotation of the rotating electric machine 21 from becoming unstable due to vibrations of the rotating electric machine 21 caused by the back electromotive force of the rotating electric machine 21, and to prevent the vehicle's running from being affected.

In this embodiment, when a cutoff command for the main relays RM1 and RM2 is output, the rotation speed NA of the rotating electric machine 21 is reduced by the reduction in the vehicle speed XA associated with the restriction of the engine driving force. This allows the desired voltage reduction in the path voltage VA to occur. In addition, when the main relays RM1 and RM2 are diagnosed as normal by the diagnostic process, the reduction in the vehicle speed XA is released by releasing the driving force restriction on the engine 31, so that the vehicle's running speed can be appropriately controlled each time depending on whether the main relays RM1 and RM2 are normal or have an on-failure. Specifically, when the main relays RM1 and RM2 are normal, the driving force restriction on the engine 31 is released, allowing the vehicle to return to proper running. In addition, when the main relays RM1 and RM2 have an on-failure, the driving force restriction on the engine 31 is maintained, allowing the vehicle to be stopped safely.

Second Embodiment
The second embodiment will be described below with reference to Fig. 7, focusing on the differences from the first embodiment. The present embodiment differs from the first embodiment in that, in the diagnosis process, an on-failure of the main relays RM1, RM2 is diagnosed based on the power supply current IA in addition to the slope KA of the path voltage VA.

Figure 7 shows a flowchart of the diagnostic process in this embodiment. For convenience, the same steps in Figure 7 as those shown in Figure 3 above are given the same step numbers and will not be described.

In the diagnosis process of this embodiment, first, in steps S21 to S28, the slope KA of the path voltage VA (the ratio of the voltage difference ΔV of the path voltage VA to the amount of change ΔN in the rotation speed NA) is calculated, and it is determined whether the slope KA is equal to or greater than the slope threshold value Kth. If a positive determination is made in step S28, the process proceeds to step S29, where the main relays RM1 and RM2 are diagnosed as normal.

On the other hand, if the determination in step S28 is negative, the process proceeds to step S41, where the power supply current (detected current) IA is acquired. At this time, the power supply current IA after the output of the cutoff command is acquired. In the following step S42, it is determined whether the absolute value of the power supply current IA acquired in step S41 is equal to or greater than the predetermined current value Ith. If the absolute value of the power supply current IA is less than the predetermined current value Ith, the process proceeds to step S29, where the main relays RM1 and RM2 are diagnosed as normal. On the other hand, if the absolute value of the power supply current IA is equal to or greater than the predetermined current value Ith, the process proceeds to step S31, where the main relays RM1 and RM2 are diagnosed as having an ON fault. The process in step S28 corresponds to the "first determination process", and the process in step S42 corresponds to the "second determination process". In addition, the slope threshold value Kth corresponds to the "voltage threshold value", and the predetermined current value Ith corresponds to the "current threshold value".

According to the present embodiment described above in detail, a judgment is made using the slope KA and a judgment is made using the power supply current IA, and when it is judged that the slope KA is less than the slope threshold value Kth and the power supply current IA is judged to be equal to or greater than the predetermined current value Ith, the main relays RM1, RM2 are diagnosed as having an on-failure. By diagnosing the on-failure of the main relays RM1, RM2 using the slope KA and the power supply current IA, it is possible to properly perform the on-failure diagnosis of the main relays RM1, RM2 while suppressing erroneous diagnosis of the on-failure compared to a case where the on-failure of the main relays RM1, RM2 is diagnosed using only the slope KA.

Third Embodiment
The third embodiment will be described below with reference to Figures 8 to 11, focusing on the differences from the second embodiment. In this embodiment, the difference from the second embodiment is that in the diagnosis process, the capacitor is discharged twice, and three combinations of the path voltage VA and the rotation speed NA are obtained in accordance with the capacitor discharges. Then, an approximate line LK that linearly approximates the relationship between the path voltage VA and the rotation speed NA is calculated using the three combinations of the path voltage VA and the rotation speed NA obtained, and an on-failure of the main relays RM1, RM2 is diagnosed based on the slope of the approximate line LK and the variation of the path voltage VA with respect to the approximate line LK.

Figure 8 shows a flowchart of the diagnostic process in this embodiment. For convenience, the same steps in Figure 8 as those shown in Figure 7 are given the same step numbers and will not be described.

In the diagnosis process of this embodiment, when the second voltage V2 and the second rotation speed N2 are acquired in step S25, the process proceeds to step S51, where it is determined whether or not the second rotation speed N2 acquired in step S25 is sufficiently small. Specifically, it is determined whether or not the second rotation speed N2 is smaller than the reference rotation speed NK. This reference rotation speed NK is set to a rotation speed lower than the predetermined rotation speed Nth used to determine whether or not to discharge the smoothing capacitor 26 in the first discharge of the smoothing capacitor 26. If the second rotation speed N2 is smaller than the reference rotation speed NK, the process proceeds to step S26. In other words, the slope KA of the path voltage VA is calculated from the combination of the first voltage V1 and the first rotation speed N1 and the combination of the second voltage V2 and the second rotation speed N2, and the on-failure of the main relays RM1 and RM2 is diagnosed. The combination of the first voltage V1 and the first rotation speed N1 corresponds to the "first data", and the combination of the second voltage V2 and the second rotation speed N2 corresponds to the "second data".

On the other hand, if the second rotation speed N2 is greater than the reference rotation speed NK, the process proceeds to step S52, where the smoothing capacitor 26 is discharged for a predetermined period after waiting for the rotation speed NA of the rotating electric machine 21 to drop from the second rotation speed N2 by a predetermined value or more. In other words, the smoothing capacitor 26 is discharged a second time. In the following step S53, the path voltage VA and the rotation speed NA are acquired after the path voltage VA becomes stable after the discharge of the smoothing capacitor 26 in step S52. Hereinafter, the path voltage VA and the rotation speed NA acquired in step S53 are referred to as the third voltage V3 and the third rotation speed N3. The combination of the third voltage V3 and the third rotation speed N3 corresponds to the "third data".

In step S54, the slope KA and variation ΔK of the path voltage VA are calculated using the detection values V1, V2, V3, N1, N2, and N3. Specifically, an approximate line LK is calculated by linearly approximating the relationship between the path voltages V1 to V3 and the rotation speeds N1 to N3, and the slope of the approximate line LK is calculated as the slope KA of the path voltage VA. The approximate line LK is calculated, for example, by the least squares method. In addition, the variation of the path voltages V1 to V3 with respect to the approximate line LK is calculated as the variation ΔK. The variation ΔK of the path voltages V1 to V3 with respect to the approximate line LK is, for example, the sum of the voltage deviations (voltage differences) of the path voltages V1 to V3 with respect to the approximate line LK.

In step S55, it is determined whether the slope KA calculated in step S54 is equal to or greater than the slope threshold Kth. If the slope KA is equal to or greater than the slope threshold Kth, the process proceeds to step S29, where the main relays RM1 and RM2 are diagnosed as normal. On the other hand, if the slope KA is less than the slope threshold Kth, the process proceeds to step S56.

In step S56, it is determined whether the variation ΔK calculated in step S54 is equal to or less than a predetermined variation threshold ΔKth. If the variation ΔK is greater than the variation threshold ΔKth, the reliability of the slope KA calculated in step S54 is low, and the accuracy of the determination result in step S55 is low, so the process proceeds to step S29 and it is determined that the main relays RM1 and RM2 are normal. On the other hand, if the variation ΔK is equal to or less than the variation threshold ΔKth, the reliability of the slope KA calculated in step S54 is high, and the accuracy of the determination result in step S55 is high, so the process proceeds to step S41.

The procedure for the diagnostic process will now be described with reference to Figures 9 and 10. (A) to (G) in Figures 9 and 10 are the same as (A) to (G) in Figures 4 and 5. In Figures 9 and 10, the process from time t1 to t6 is the same as in Figures 4 and 5, and so duplicated explanations will be omitted.

In FIG. 9, the main relays RM1 and RM2 are assumed to be normal, and when the second voltage V2 and the second rotation speed N2 are acquired at time t6, it is determined whether the second rotation speed N2 is greater than the reference rotation speed NK. In the example shown in FIG. 9, the second rotation speed N2 is greater than the reference rotation speed NK. Therefore, when the rotation speed NA of the rotating electric machine 21 drops from the second rotation speed N2 by a predetermined value at time t11, the smoothing capacitor 26 is discharged for a predetermined period from time t11 to t12. When the discharge of the smoothing capacitor 26 is stopped at time t12, and the path voltage VA rises to the back electromotive voltage of the rotating electric machine 21 at time t13, the third voltage V3 and the third rotation speed N3 are acquired.

When the third voltage V3 and the third rotation speed N3 are acquired, the slope KA and variation ΔK of the path voltage VA are calculated using the respective detection values V1, V2, V3, N1, N2, and N3. In FIG. 9, the path voltages V1 to V3 decrease as the rotation speeds N1 to N3 decrease. Therefore, as shown in FIG. 11(A), the slope KA is equal to or greater than the slope threshold Kth. In addition, the path voltages VA and rotation speeds NA of the three combinations are located near the approximate line LK, and the variation ΔK with respect to the approximate line LK is equal to or less than the variation threshold ΔKth. Therefore, based on the slope KA and variation ΔK of the path voltage VA, the main relays RM1 and RM2 are diagnosed as normal.

Even if the main relays RM1 and RM2 are normal, the path voltage VA may change due to detection errors or noise of the voltage sensor 27, and for example, the third voltage V3 may become a voltage value larger than the slope of the second voltage V2. In this case, as shown in FIG. 11B, the slope KA is less than the slope threshold Kth. On the other hand, the path voltages VA and the rotation speeds NA of the three combinations are separated from the approximate straight line LK, and the variation ΔK calculated as the sum of the voltage deviation amount VS1 of the first voltage V1 with respect to the approximate straight line LK, the voltage deviation amount VS2 of the second voltage V2 with respect to the approximate straight line LK, and the voltage deviation amount VS3 of the third voltage V3 with respect to the approximate straight line LK becomes larger than the variation threshold ΔKth. In other words, even if the slope KA is less than the slope threshold Kth, the reliability of the slope KA is low, so that the main relays RM1 and RM2 are diagnosed as normal. This makes it possible to prevent erroneous diagnosis of on-failures and properly perform on-failure diagnosis of main relays RM1 and RM2.

On the other hand, FIG. 10 shows the transition of each value when the main relays RM1, RM2 have an on-failure. In this case, when the discharge of the smoothing capacitor 26 is stopped at time t12, the route voltage VA rises to the power supply voltage VB, and the third voltage V3 has substantially the same value as the first voltage V1 and the second voltage V2. Therefore, as shown in FIG. 11(C), the slope KA is less than the slope threshold Kth. In addition, the route voltage VA and the rotation speed NA of the three combinations are located near the approximate line LK, and the variation ΔK with respect to the approximate line LK is less than the variation threshold ΔKth. Therefore, based on the slope KA and variation ΔK of the route voltage VA, the main relays RM1, RM2 are diagnosed as having an on-failure.

The present embodiment described above provides the following advantages:

In this embodiment, in a situation where the rotation speed NA of the rotating electric machine 21 decreases after the output of a cutoff command for the main relays RM1 and RM2, the smoothing capacitor 26 is discharged multiple times, and an approximate straight line LK is calculated from the rotation speed NA and the path voltage VA obtained for each capacitor discharge. In addition, an on-fault of the main relays RM1 and RM2 is diagnosed based on the slope KA of the approximate straight line LK and the variation ΔK of the path voltage VA with respect to the approximate straight line LK. In this case, the reliability of the slope KA of the approximate straight line LK can be determined based on the variation ΔK, and an erroneous diagnosis of an on-fault of the main relays RM1 and RM2 can be properly performed by suppressing the erroneous diagnosis of an on-fault of the main relays RM1 and RM2.

When discharging the smoothing capacitor 26 multiple times and diagnosing an on-fault of the main relays RM1, RM2 based on the approximate straight line LK calculated from the rotation speed NA and path voltage VA for each capacitor discharge and the variation ΔK of the path voltage VA relative to the approximate straight line LK, it is possible to improve the accuracy of the fault diagnosis, but there is a concern that the fault diagnosis will take time because multiple capacitor discharges are required. In addition, if the rotating electric machine 21 is in a low rotation state, it may be impossible to predict a change in the rotation speed from that point on.

In this regard, in the present embodiment, if the second rotation speed N2 obtained after the first capacitor discharge is higher than the reference rotation speed NK, the three combinations of rotation speed NA and path voltage VA are used to diagnose an ON fault in the main relays RM1 and RM2, whereas if the second rotation speed N2 is lower than the reference rotation speed NK, the first voltage V1 and first rotation speed N1 and the second voltage V2 and second rotation speed N2 are used to diagnose an ON fault in the main relays RM1 and RM2. This allows for proper fault diagnosis to be performed while taking into account the rotation state of the rotating electric machine 21.

Fourth Embodiment
In this embodiment, a power supply system mounted on a propeller-type electric flying object will be described. Fig. 12 is a schematic diagram showing the configuration of a control system 60 as a power supply system for the flying object in this embodiment. In Fig. 12, the control system 60 has a battery 61, a plurality of propeller units 70, and a control device 80. The battery 61 is the power source for the flying object, and supplies power to each propeller unit 70 via a power line 62. The flying object flies with the rotation of the propeller 71 of each propeller unit 70. In this embodiment, the flying object corresponds to a "moving object."

The propeller unit 70 has a propeller 71, a rotating electric machine 72 that rotates the propeller 71, an inverter 73 that adjusts the input and output of power to the rotating electric machine 72, and a power switch 75 provided on a positive power supply path 74 extending from the power line 62. The rotating electric machine 72 is a rotating electric machine having a multi-phase stator winding, similar to the rotating electric machine 21 described above, and the inverter 73 is a power conversion circuit having multiple switching elements for each phase, similar to the inverter 24 described above. The power switch 75 constitutes a main relay, and the power supply state and the power cut-off state between the battery 61 and the inverter 73 are switched by turning the power switch 75 on and off. In each propeller unit 70, a smoothing capacitor 76 and a voltage sensor 77 are connected to the inverter 73 side of the power switch 75. The voltage sensor 77 detects the voltage between the positive power supply path 74 as a path voltage VA.

In FIG. 12, the power switch 75 is provided only on the positive side path out of the positive and negative side paths, but the power switch 75 may be provided on both the positive and negative paths. Also, although not shown in FIG. 12, a series connection of a precharge relay and a resistor may be connected in parallel to the power switch 75 (see FIG. 1).

Although not shown, each propeller unit 70 has a current sensor that detects the power supply current flowing through the positive power supply path 74, and a rotation speed sensor that detects the number of rotations per unit time NA of the rotating electric machine 72, i.e., the rotation speed.

Each propeller unit 70 has the same configuration, and is individually controlled by the control device 80. The control device 80 appropriately controls the open/close state of the power switch 75 in each propeller unit 70 and controls the rotation of the propeller 71, based on flight requirements and detection information from each of the above sensors.

The flying object of this embodiment is capable of flying in the vertical direction and the horizontal direction. For example, the flying object moves in the vertical direction during takeoff and landing, and moves in the horizontal direction during movement to the destination. In this case, each propeller unit 70 may be used according to the flight situation, and the multiple propeller units 70 may include a propeller unit 70 for vertical flight and a propeller unit 70 for horizontal flight. The propeller unit 70 for vertical flight may also be called a propeller unit 70 for takeoff and landing. However, it is also possible to drive the propeller unit 70 for vertical flight and the propeller unit 70 for horizontal flight simultaneously. For example, in the propeller unit 70 for vertical flight, the rotation axis of the propeller 71 may be arranged to extend vertically or approximately vertically, and in the propeller unit 70 for horizontal flight, the rotation axis of the propeller 71 may be arranged to extend horizontally or approximately horizontally.

The propeller unit 70 for vertical flight and the propeller unit 70 for horizontal flight may have different maximum outputs. For example, the propeller unit 70 for vertical flight may have a relatively large maximum output, and the propeller unit 70 for horizontal flight may have a relatively small maximum output. However, the opposite may also be true.

The flying object is capable of flying with the propellers 71 of some of the propeller units 70 rotated, and during takeoff and landing or low-speed flight, flight is possible with only some of the propellers 71 rotating. Furthermore, if an abnormality occurs in some of the propeller units 70 of the flying object, the rotation of the propeller 71 in that propeller unit 70 is stopped, and flight is possible with the propellers 71 of the remaining propeller units 70 rotating.

The control device 80 also has a function of diagnosing a fault in the power switch 75 when a predetermined switch diagnosis condition is met. For example, when the rotation of the propellers 71 in some of the propeller units 70 is stopped during flight of the aircraft, in other words, when the rotation of the propellers 71 in the propeller units 70 in the driven state becomes unnecessary, the switch diagnosis condition is deemed to be met for that propeller unit 70, and a fault diagnosis of the power switch 75 is performed.

More specifically, when the aircraft transitions from a takeoff state to a horizontal flight state, the propeller unit 70 for vertical flight is stopped from the driven state. At this time, it is preferable to set the switch diagnosis condition for the propeller unit 70 for vertical flight as the target of the fault diagnosis. Or, when the aircraft transitions from a horizontal flight state to a landing state, the propeller unit 70 for horizontal flight is stopped from the driven state. At this time, it is preferable to set the switch diagnosis condition for the propeller unit 70 for horizontal flight as the target of the fault diagnosis. In addition, when the flight speed of the aircraft is reduced, some of the propeller units 70 that are being driven are stopped. At this time, it is preferable to set the switch diagnosis condition for the propeller unit 70 that is being stopped as the target of the fault diagnosis. The propeller unit 70 to be diagnosed does not have to be one, and it is also possible to simultaneously set two or more propeller units 70 as the target of the diagnosis.

In addition, if an overcurrent flows through the positive power supply path 74 in each propeller unit 70 due to an abnormality in the inverter 73, etc., it is possible to determine that the switch diagnosis conditions are met and to perform a fault diagnosis of the power supply switch 75.

In this embodiment, when the power switch 75 is in a closed state (conducting state) and the switch diagnosis condition is satisfied, a shutoff command is output to shut off the power switch 75 with the control of the inverter 73 stopped. In addition, in a situation in which the rotation speed NA of the rotating electric machine 72 changes after the shutoff command is output, a voltage difference ΔV in the path voltage VA before and after the change in the rotation speed NA is obtained, and an ON failure of the power switch 75 is diagnosed based on the voltage difference ΔV.

Figure 13 shows a flowchart of the control process of this embodiment. The control device 80 repeatedly executes this control process for each propeller unit 70 at a predetermined interval while the aircraft is flying.

When the control process is started, in step S61, it is determined whether or not the diagnostic conditions are met for the propeller unit 70 to be diagnosed this time, and if the diagnostic conditions are met, the process proceeds to the following step S62. In step S62, the control of the inverter 73 is stopped. This stops the power drive of the propeller 71 by the rotating electric machine 72, and the propeller rotation speed begins to gradually decrease, and the rotation speed of the rotating electric machine 72 decreases. At this time, the rotation speed of the propeller 71 gradually decreases with a predetermined inertial force. Alternatively, the propeller 71 may rotate by inertia due to the wind after the power drive is stopped. In the following step S63, a shutoff command is output to shut off the power switch 75.

Then, in step S64, the path voltage (detected voltage) VA is acquired as the first voltage V11 in the propeller unit 70, and the rotation speed NA is acquired as the first rotation speed N11. At this time, it is preferable that the first voltage V11 and the first rotation speed N11 are acquired after the path voltage VA becomes stable after the cutoff command is output.

Then, in step S65, while the rotating electric machine 72 is rotating, the smoothing capacitor 76 is discharged for a predetermined period. At this time, the smoothing capacitor 76 is discharged for a period longer than the period required for the route voltage VA to decrease to the electromotive force voltage (back electromotive voltage) due to the back electromotive force of the rotating electric machine 72. This discharge causes the route voltage VA to decrease below the back electromotive voltage of the rotating electric machine 72. In step S65, the capacitor discharge may be performed on the condition that the rotation speed of the rotating electric machine 72 is equal to or lower than a predetermined value. In other words, the capacitor discharge may be performed on the condition that the rotation speed of the rotating electric machine 72 is such that the back electromotive voltage is smaller than the predetermined voltage.

In step S66, the path voltage VA after the capacitor discharge is obtained as the second voltage V12, and the rotation speed NA is obtained as the second rotation speed N12. At this time, it is preferable that the second voltage V12 and the second rotation speed N12 are obtained after the transient change in the path voltage VA has converged. In step S67, the difference between the first rotation speed N11 and the second rotation speed N12 is calculated as the change amount ΔN in the rotation speed NA, and the difference between the first voltage V11 and the second voltage V12 is calculated as the voltage difference ΔV in the path voltage VA.

Then, in step S68, it is determined whether or not the power switch 75 has an on-failure based on the change in rotation speed and voltage before and after the capacitor discharge. If it is determined that the power switch 75 does not have an on-failure (i.e., the power switch 75 is normal), this process ends, but if it is determined that the power switch 75 has an on-failure, the process proceeds to step S69.

Specifically, in step S68, the slope KA of the change in path voltage VA before and after the change in rotation speed NA is calculated from the amount of change ΔN in rotation speed NA and the voltage difference ΔV in path voltage VA (KA=ΔV/ΔN), and based on this slope KA, it is determined whether or not the power switch 75 has an on-failure. If the slope KA is equal to or greater than a predetermined value, the power switch 75 is deemed to be normal, and the process is terminated. If the slope KA is less than the predetermined value, the power switch 75 is deemed to have an on-failure, and the process proceeds to step S69.

In step S69, the malfunction information for the propeller unit 70 currently being diagnosed is stored in memory, and then the process ends. Thereafter, it is advisable to prohibit use of the propeller unit 70 currently being diagnosed.

In addition, in this embodiment, when some of the propeller units 70 are stopped while the aircraft is flying, and a cutoff command is output for the propeller units 70 to be stopped, a power command to maintain the flying state of the aircraft is output to the other propeller units 70 to which the cutoff command has not been output. Specifically, the control device 80 executes the process of FIG. 14. This process may be rewritten and executed as the process of FIG. 13.

In FIG. 14, in step S71, it is determined whether or not the diagnostic conditions are met for the propeller unit 70 currently being diagnosed, and if the diagnostic conditions are met, the process proceeds to the subsequent step S72. In step S72, a power command value required to maintain flight of the aircraft with the propeller units 70 not currently being diagnosed is calculated, and this power command value is output to the propeller units 70 that are currently being diagnosed. In addition, in step S73, control of the inverter 73 is stopped for the propeller unit 70 currently being diagnosed. As a result, the propeller speed is reduced in the propeller unit 70 currently being diagnosed, while the flight of the aircraft is enabled by driving the propeller units 70 other than that propeller unit 70.

After that, in step S74, a shutoff command is output to shut off the power switch 75, and in the following step S75, a diagnosis of an on-failure of the power switch 75 is performed. At this time, it is preferable to carry out processing similar to steps S64 to S68 in FIG. 13.

Then, in step S76, it is determined whether the power switch 75 is normal. If it is determined that the power switch 75 is normal, the process proceeds to step S77. In step S77, it is determined whether there is a request to increase the propeller rotation speed of the propeller unit 70 currently being diagnosed. If it is determined that there is a request to increase the propeller rotation speed, the process proceeds to step S78, where the power command value of each propeller unit 70 in the state in which the propeller unit 70 currently being diagnosed is re-driven is calculated again, and the power command value is output to each propeller unit 70. In the following step S79, the drive of the propeller unit 70 currently being diagnosed is resumed. Note that, if it is determined in step S77 that there is no request to increase the propeller rotation speed of the propeller unit 70 currently being diagnosed, the process ends as it is.

If the power switch 75 has an ON failure and step S76 is negative, the process proceeds to step S80. In step S80, the use of the propeller unit 70 currently being diagnosed is prohibited, and then the process ends.

As described above, this embodiment can achieve the following excellent effects:

When a command to shut off the power switch 75 is output in an aircraft, the propeller speed decreases and the rotating electric machine 72 speed decreases, thereby causing the desired voltage drop required for fault diagnosis of the power switch 75 on the inverter 73 side.

In addition, if the power switch 75 is determined to be normal and there is a request to increase the propeller rotation speed, the reduced rotation speed state of the propeller 71 is released. This allows the flight of the aircraft to be suitably restored to the flight state before diagnosis after a fault diagnosis of the power switch 75.

When some of the propeller units 70 are stopped from a driven state during flight of an aircraft equipped with multiple propeller units 70, it is assumed that the switch diagnostic conditions are met for the propeller units 70 to be stopped, and a shutoff command is output. In this case, the success or failure of the diagnostic conditions is determined according to the flight state of the aircraft, for example, the timing when the aircraft transitions from a takeoff state to a horizontal flight state, and a shutoff command for the power switch 75 is output. Therefore, a fault diagnosis can be performed on the propeller units 70 that are stopped from being driven, without affecting the flight status of the aircraft.

When the drive of some of the propeller units 70 is stopped while the aircraft is flying, and a shutoff command is output for the propeller units 70 to be shut off, a power command value is output to the other propeller units 70 to which the shutoff command has not been output, to maintain the aircraft's moving state. As a result, when the drive of any of the multiple propeller units 70 is stopped to perform a fault diagnosis of the propeller unit 70, the flight state of the aircraft is maintained without change before and after the drive is stopped. As a result, a fault diagnosis of the propeller units 70 can be performed without affecting the flight status of the aircraft.

In the fourth embodiment, an aircraft is assumed as the moving body, and multiple propeller units 70 are assumed as the multiple drive units, but this configuration may be changed. For example, an electric vehicle may be assumed as the moving body, and multiple wheel units may be assumed as the multiple drive units. The wheel units may be, for example, in-wheel motors in which a rotating electric motor is integrated into the wheels. In this case, the electric vehicle is capable of running by driving some of the wheel units among all the wheel units. For example, the electric vehicle may have a front wheel unit and a rear wheel unit, and may be capable of running by driving at least one of the front and rear wheel units.

When the control device stops some of the multiple wheel units in a driven state while the electric vehicle is traveling, it determines that the switch diagnosis condition is met for the wheel unit to be stopped, and outputs a power switch shutoff command. It then obtains a voltage difference, which is the difference in detected voltages according to the change in the rotation speed of the rotating electric machine that occurs after the shutoff command is output, and diagnoses an on-failure of the power switch based on the voltage difference.

In addition, when some wheel units are stopped while the electric vehicle is running, and a cut-off command is output for the wheel units to be stopped, a power command to maintain the running state of the electric vehicle may be output to the other wheel units to which the cut-off command has not been output.

<Other embodiments>
Each of the above embodiments may be modified as follows.

- In the above embodiment, for example, a configuration is shown in which the slope KA of the path voltage VA is used to diagnose an on-failure of the main relays RM1, RM2, but this is not limited to the above. For example, the voltage difference ΔV of the path voltage VA before and after a change in the rotation speed NA may be used to diagnose an on-failure of the main relays RM1, RM2. Specifically, the on-failure of the main relays RM1, RM2 may be diagnosed based on whether the voltage difference ΔV of the path voltage VA before and after a change in the rotation speed NA is equal to or greater than a predetermined voltage difference threshold ΔVth. In this case, when the amount of change ΔN in the rotation speed NA before and after the change in the rotation speed NA is large, the voltage difference threshold ΔVth may be set to a larger value than when it is small.

- In the second embodiment, an example of diagnosing an on-failure of the main relays RM1 and RM2 based on the slope KA of the path voltage VA and the power supply current IA after the output of the cutoff command is shown, but this is not limited to this. Furthermore, the power supply current IA before the output of the cutoff command may be acquired, and the on-failure of the main relays RM1 and RM2 may be diagnosed using the current change between the power supply current IA before the output of the cutoff command and the power supply current IA after the output of the cutoff command. Specifically, when the slope KA of the path voltage VA is less than the slope threshold Kth and the absolute value of the power supply current IA after the output of the cutoff command is equal to or greater than a predetermined current value Ith, it may be further determined whether the current change of the power supply current IA before and after the output of the cutoff command is greater than a predetermined change threshold. Then, if the current change is smaller than the change threshold, it is preferable to diagnose that the main relays RM1 and RM2 have an on-failure. Also, if the current change is greater than the change threshold, it is preferable to diagnose that the main relays RM1 and RM2 are normal.

- In the third embodiment, an example was shown in which the combination of the path voltage VA and the rotation speed NA was obtained three times, but the number of times the combination of the path voltage VA and the rotation speed NA was obtained is not limited to three, and may be four or more times. In this case, when the number of times the combination of the path voltage VA and the rotation speed NA is obtained is large, the variation threshold value ΔKth may be set to a larger value than when the number of times is small.

- In the first to third embodiments described above, the method of limiting the driving force of the engine 31 is exemplified as a method of reducing the rotation speed NA of the rotating electric machine 21 after the output of a discharge command, but this is not limited to this. For example, the gear mechanism 34 may be configured to be able to change the gear ratio GA of the rotating shaft 22 relative to the axle 51, and when reducing the rotation speed NA, the gear ratio GA of the rotating shaft 22 relative to the axle 51 may be increased. In this embodiment, the axle 51 corresponds to the "rotation transmission path."

Figure 15 shows a flowchart of the diagnostic process in another embodiment. In Figure 15, the same processes as those shown in Figure 3 above are given the same step numbers for convenience, and the explanation is omitted.

In this embodiment, the first voltage V1 and the first rotation speed N1 are obtained in step S22 without limiting the driving force of the engine 31, and the process proceeds to step S91. In step S91, the gear ratio GA is increased while the vehicle is traveling after the output of the shutoff command. The increase in the gear ratio GA reduces the rotation speed NA of the rotating electric machine 21. In the following step S25, the second voltage V2 and the second rotation speed N2 are obtained. Therefore, in step S26, the voltage difference ΔV of the path voltage VA before and after the increase in the gear ratio GA is calculated. In this embodiment, the process of step S91 corresponds to the "gear ratio adjustment unit."

In this embodiment, the rotation speed NA of the rotating electric machine 21 can be reduced while suppressing a decrease in the vehicle speed XA, making it possible to reduce the discomfort caused by deceleration while the vehicle is traveling.

- The switch diagnosis condition is not limited to the occurrence of a specific abnormality. For example, when periodically diagnosing power switch ON failures, the satisfaction of a periodic diagnosis condition, such as the passage of a specified diagnosis period, may be regarded as the switch diagnosis condition.

In addition to the occurrence of a specific abnormality, the satisfaction of a periodic diagnosis condition may be regarded as a switch diagnosis condition. In this case, if the diagnosis process is executed on the condition that a specific abnormality has occurred, it is preferable to maintain the prohibition of the vehicle from being driven by the rotating electric machine 21 even if the main relays RM1 and RM2 are diagnosed as normal in step S16 of the diagnosis process. On the other hand, if the diagnosis process is executed on the condition that a periodic diagnosis condition has been satisfied, the prohibition of the vehicle from being driven by the rotating electric machine 21 may be lifted if the main relays RM1 and RM2 are diagnosed as normal in step S16 of the diagnosis process. This makes it possible to switch whether or not to allow the vehicle to be driven by the rotating electric machine 21 depending on the type of switch diagnosis condition.

- When the present invention is realized as an on-board power supply system, it can be applied to a hybrid vehicle in which the engine 31 can run independently and the rotating electric machine 21 and the wheels 50 rotate together. In this case, the connection structure between the engine 31 and the rotating electric machine 21 in the hybrid vehicle is not limited to the above embodiment, and can be applied to hybrid vehicles with a well-known connection structure.

The diagnostic device and method described in the present disclosure may be realized by a dedicated computer provided by configuring a processor and memory programmed to execute one or more functions embodied in a computer program. Alternatively, the diagnostic device and method described in the present disclosure may be realized by a dedicated computer provided by configuring a processor with one or more dedicated hardware logic circuits. Alternatively, the diagnostic device and method described in the present disclosure may be realized by one or more dedicated computers configured by combining a processor and memory programmed to execute one or more functions with a processor configured with one or more hardware logic circuits. In addition, the computer program may be stored in a computer-readable non-transient tangible recording medium as instructions executed by the computer.

The technical ideas extracted from the above-described embodiments will be described below.
[Configuration 1]
A power source (23, 61);
an inverter (24, 73) connected to the power supply;
A rotating electric machine (21, 72) connected to the inverter;
a power switch (RM1, RM2, 75) provided in a power path between the power supply and the inverter;
a voltage sensor (27, 77) for detecting a path voltage which is a voltage of the power supply path on the inverter side relative to the power supply switch;
The present invention is applied to a power supply system (10, 60) including:
a shutoff command unit that outputs a shutoff command to shut off the power switch while stopping control of the inverter when a predetermined switch diagnosis condition is satisfied in a conductive state of the power switch;
an acquisition unit that acquires a voltage difference that is a difference between the detected voltages of the voltage sensors in response to a change in the rotation speed of the rotating electric machine after the shutdown command unit outputs the shutdown command;
a diagnosis unit that diagnoses an on-failure of the power switch based on the voltage difference;
A diagnostic device (40, 80) comprising:
[Configuration 2]
In the power supply system, a smoothing capacitor (26, 76) is connected in parallel to the power supply in the power supply path on the inverter side relative to the power switch,
a discharge processing unit that discharges the smoothing capacitor in a situation where a decrease in the rotation speed occurs after the cutoff command is output by the cutoff command unit,
The diagnostic device according to configuration 1, wherein the acquisition unit acquires, as the voltage difference, a difference between the detected voltage before the discharge processing unit discharges the smoothing capacitor and the detected voltage after the discharge of the smoothing capacitor in a situation in which a decrease in the rotation speed occurs after the output of the shut-off command.
[Configuration 3]
3. The diagnostic device according to claim 2, wherein the discharge processing unit discharges the smoothing capacitor so that the path voltage becomes lower than an electromotive force voltage of the rotating electric machine when the discharge of the smoothing capacitor ends.
[Configuration 4]
The discharge processing unit enables discharging of the smoothing capacitor multiple times under a situation in which a decrease in the rotation speed occurs after the output of the interruption command,
the acquisition unit acquires the rotation speed and the path voltage before a first discharge of the smoothing capacitor and after each subsequent discharge of the smoothing capacitor when the smoothing capacitor is discharged a plurality of times;
The diagnostic device of configuration 2 or 3, wherein the diagnosing unit calculates an approximation line that linearly approximates the relationship between the rotation speed and the path voltage using three or more combinations of the rotation speed and the path voltage acquired by the acquisition unit, and diagnoses an on-failure of the power switch based on a slope of the approximation line and a variation of the path voltage with respect to the approximation line.
[Configuration 5]
the acquisition unit acquires, under a circumstance in which a decrease in the rotation speed occurs after the output of the shutoff command, the rotation speed and the path voltage before and after a first capacitor discharge by the discharge processing unit as first data and second data, respectively, and acquires the rotation speed and the path voltage after a subsequent second capacitor discharge as third data;
The diagnostic device according to configuration 4, wherein if the rotation speed of the rotating electric machine is higher than a predetermined value at the time when the second data is acquired, the diagnostic unit acquires the first to third data and diagnoses an on-failure of the power supply switch using the first to third data, and if the rotation speed of the rotating electric machine is lower than a predetermined value at the time when the second data is acquired, the diagnostic unit acquires the first and second data of the first to third data and diagnoses an on-failure of the power supply switch using the first and second data.
[Configuration 6]
The power supply system includes a current sensor (28) for detecting a power supply current that is a current flowing through the power supply;
The acquisition unit acquires a detected current of the current sensor after the shutdown command is output by the shutdown command unit,
The diagnosis unit includes:
a first determination process for determining whether the voltage difference is greater than a predetermined voltage threshold, and a second determination process for determining whether the detected current is greater than a predetermined current threshold,
The diagnostic device of any one of configurations 1 to 5, wherein when the first determination process determines that the voltage difference is smaller than the voltage threshold value and the second determination process determines that the detected current is larger than the current threshold value, the diagnostic device diagnoses that the power switch has an on-failure.
[Configuration 7]
The power supply system is mounted on a vehicle in which the rotating electric machine is capable of rotating in accordance with the rotation of wheels (50),
The diagnostic device according to any one of configurations 1 to 6, further comprising a speed control unit that, when the shutoff command is output by the shutoff command unit, reduces the traveling speed of the vehicle to reduce the rotation speed of the rotating electric machine, and, when the diagnosis unit determines that the power switch is normal, cancels the reduced state of the traveling speed.
[Configuration 8]
The power supply system is mounted on a vehicle having a gear mechanism (34) that changes a gear ratio in a rotation transmission path between wheels (50) and the rotating electric machine,
a gear ratio adjusting unit that increases a gear ratio of the rotating electric machine side to the wheel side during vehicle traveling after the cutoff command is output by the cutoff command unit,
The diagnostic device according to any one of configurations 1 to 6, wherein the acquisition unit acquires, as the voltage difference, a difference between the detected voltage before the gear ratio is increased by the gear ratio adjustment unit and the detected voltage after the gear ratio is increased.
[Configuration 9]
The power supply system rotates a propeller (71) using the rotating electric machine in an aircraft that flies in accordance with the rotation of the propeller,
The diagnostic device according to any one of configurations 1 to 6, further comprising a propeller rotation control unit that reduces a rotation speed of the rotating electric machine together with a reduction in a rotation speed of the propeller when the shutdown command is output by the shutdown command unit.
[Configuration 10]
The diagnostic device according to configuration 9, wherein the propeller rotation control unit releases the reduced state of the propeller rotation speed when, after the shut-off command is output and the diagnosis unit has performed, it is determined that the power switch is normal and there is a request to increase the rotation speed of the propeller.
[Configuration 11]
The power supply system is applied to a moving body including a plurality of drive units each including the inverter, the rotating electric machine, the power switch, and the voltage sensor, and the moving body is capable of moving by driving some of all of the drive units;
The diagnostic device described in any one of configurations 1 to 6, wherein when some of the multiple drive units that are in a driven state are to be stopped while the moving body is moving, the cut-off command unit determines that the switch diagnosis condition is satisfied for the drive unit to be stopped, and outputs the cut-off command.
[Configuration 12]
The diagnostic device described in configuration 11, further comprising a power control unit that outputs a power command value for maintaining the moving state of the moving body to the other drive units to which the shut-off command has not been output when the drive of some of the drive units is stopped while the moving body is moving and when the shut-off command unit outputs the shut-off command for the drive units to be stopped.

10...control system, 23...battery, 24...inverter, 27...voltage sensor, 40...control device, RM1...first main relay, RM2...second main relay.

Claims (13)

A power source (23, 61);
an inverter (24, 73) connected to the power supply;
A rotating electric machine (21, 72) connected to the inverter;
a power switch (RM1, RM2, 75) provided in a power path between the power supply and the inverter;
a voltage sensor (27, 77) for detecting a path voltage which is a voltage of the power supply path on the inverter side relative to the power supply switch;
The present invention is applied to a power supply system (10, 60) including:
a shutoff command unit that outputs a shutoff command to shut off the power switch while stopping control of the inverter when a predetermined switch diagnosis condition is satisfied in a conductive state of the power switch;
an acquisition unit that acquires a voltage difference that is a difference between the detected voltages of the voltage sensors in response to a change in the rotation speed of the rotating electric machine after the shutdown command unit outputs the shutdown command;
a diagnosis unit that diagnoses an on-failure of the power switch based on the voltage difference;
A diagnostic device (40, 80) comprising: In the power supply system, a smoothing capacitor (26, 76) is connected in parallel to the power supply in the power supply path on the inverter side relative to the power switch,
a discharge processing unit that discharges the smoothing capacitor in a situation where a decrease in the rotation speed occurs after the cutoff command is output by the cutoff command unit,
2. The diagnostic device according to claim 1, wherein the acquisition unit acquires, as the voltage difference, a difference between the detected voltage before the discharge of the smoothing capacitor by the discharge processing unit and the detected voltage after the discharge of the smoothing capacitor in a situation in which a decrease in the rotation speed occurs after the output of the shut-off command. The diagnostic device according to claim 2, wherein the discharge processing unit discharges the smoothing capacitor so that the path voltage becomes lower than the electromotive force voltage of the rotating electric machine when the discharge of the smoothing capacitor is completed. The discharge processing unit enables discharging of the smoothing capacitor multiple times under a situation in which a decrease in the rotation speed occurs after the output of the shutoff command,
the acquisition unit acquires the rotation speed and the path voltage before a first discharge of the smoothing capacitor and after each subsequent discharge of the smoothing capacitor when the smoothing capacitor is discharged a plurality of times;
3. The diagnostic device according to claim 2, wherein the diagnosing unit calculates an approximation line that linearly approximates a relationship between the rotation speed and the path voltage using three or more combinations of the rotation speed and the path voltage acquired by the acquisition unit, and diagnoses an on-failure of the power switch based on a slope of the approximation line and a variation of the path voltage with respect to the approximation line. the acquisition unit acquires, under a circumstance in which a decrease in the rotation speed occurs after the output of the shutoff command, the rotation speed and the path voltage before and after a first capacitor discharge by the discharge processing unit as first data and second data, respectively, and acquires the rotation speed and the path voltage after a subsequent second capacitor discharge as third data;
5. The diagnostic device according to claim 4, wherein if the rotation speed of the rotating electric machine is higher than a predetermined value at the time when the second data is acquired, the diagnostic unit acquires the first to third data and diagnoses an on-failure of the power supply switch using the first to third data, and if the rotation speed of the rotating electric machine is lower than a predetermined value at the time when the second data is acquired, the diagnostic unit acquires the first and second data of the first to third data and diagnoses an on-failure of the power supply switch using the first and second data. The power supply system includes a current sensor (28) for detecting a power supply current that is a current flowing through the power supply;
The acquisition unit acquires a detected current of the current sensor after the shutdown command is output by the shutdown command unit,
The diagnosis unit includes:
a first determination process for determining whether the voltage difference is greater than a predetermined voltage threshold, and a second determination process for determining whether the detected current is greater than a predetermined current threshold,
2. The diagnostic device according to claim 1, wherein when the first determination process determines that the voltage difference is smaller than the voltage threshold value and when the second determination process determines that the detected current is larger than the current threshold value, the power switch is diagnosed as having an on-failure. The power supply system is mounted on a vehicle in which the rotating electric machine is capable of rotating in accordance with the rotation of wheels (50),
The diagnostic device according to any one of claims 1 to 6, further comprising a speed control unit that, when the shutoff command is output by the shutoff command unit, reduces the vehicle's traveling speed to reduce the rotation speed of the rotating electric machine, and, when the diagnostic unit determines that the power switch is normal, cancels the reduced state of the traveling speed. The power supply system is mounted on a vehicle having a gear mechanism (34) that changes a gear ratio in a rotation transmission path between wheels (50) and the rotating electric machine,
a gear ratio adjusting unit that increases a gear ratio of the rotating electric machine side to the wheel side during vehicle traveling after the cutoff command is output by the cutoff command unit,
The diagnostic device according to any one of claims 1 to 6, wherein the acquisition unit acquires, as the voltage difference, a difference between the detected voltage before the gear ratio is increased by the gear ratio adjustment unit and the detected voltage after the gear ratio is increased. The power supply system rotates a propeller (71) using the rotating electric machine in an aircraft that flies in accordance with the rotation of the propeller,
The diagnostic device according to claim 1 , further comprising a propeller rotation control unit that reduces a rotation speed of the rotating electric machine together with a reduction in a rotation speed of the propeller when the cutoff command is output by the cutoff command unit. The diagnostic device according to claim 9, wherein the propeller rotation control unit cancels the reduced propeller rotation speed state when the power switch is determined to be normal and there is a request to increase the propeller rotation speed after the shutoff command is output and the diagnostic unit performs a diagnosis. The power supply system is applied to a moving body including a plurality of drive units each including the inverter, the rotating electric machine, the power switch, and the voltage sensor, and the moving body is capable of moving by driving some of all of the drive units;
The diagnostic device according to claim 1, wherein when some of the plurality of drive units in a driving state are to be stopped while the moving body is moving, the cut-off command unit determines that the switch diagnosis condition is satisfied for the drive unit to be stopped, and outputs the cut-off command. The diagnostic device according to claim 11, further comprising a power control unit that outputs a power command value for maintaining the moving state of the moving body to the other driving units to which the cut-off command has not been output when the drive of some of the driving units is stopped during the movement of the moving body and the cut-off command is output by the cut-off command unit for the driving units to be stopped. A power source (23, 61);
an inverter (24, 73) connected to the power supply;
A rotating electric machine (21, 72) connected to the inverter;
a power switch (RM1, RM2, 75) provided in a power path between the power supply and the inverter;
a voltage sensor (27, 77) for detecting a path voltage which is a voltage of the power supply path on the inverter side relative to the power supply switch;
A computer-executable program for use in a power supply system (10, 60) comprising:
a shutoff command step of outputting a shutoff command to shut off the power switch while stopping control of the inverter when a predetermined switch diagnosis condition is satisfied in a conductive state of the power switch;
an acquisition step of acquiring a voltage difference which is a difference between the voltages detected by the voltage sensors in response to a change in the rotation speed of the rotating electric machine after the output of the shutoff command in the shutoff command step;
a diagnosis step of diagnosing an on-failure of the power switch based on the voltage difference;
A program that includes:

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