JP7656578B2 - Vehicle control device - Google Patents

Description

This disclosure relates to a vehicle control device.

In electrically powered vehicles such as hybrid cars, when the system is shut down, such as when the ignition power is cut off, active discharge is performed by passing current through the motor in the drive circuit to discharge the capacitor in the circuit.

At this time, if some kind of fault occurs and active discharge fails, a power conversion device has been disclosed that can identify the faulty part of the drive circuit (see, for example, Patent Document 1). Also disclosed is a power conversion device that notifies the state of a switching mechanism that electrically connects or disconnects a capacitor and the capacitor's discharge circuit, and the discharge status of the charge stored in the capacitor (see, for example, Patent Document 2).

International Publication No. 2021/039277 International Publication No. 2011/111208

Even if a discharge abnormality occurs in the capacitor and active discharge fails, there are cases where no fault is found in the drive circuit. In such cases, it is presumed that active discharge failed due to a temporary cause such as poor contact in the connector. However, because the result of the discharge abnormality determination is recorded, the system will not be allowed to start again until this record is erased, and in the worst case scenario, this could result in a breakdown on the road.

The present disclosure aims to provide a vehicle control device that can prevent restrictions on system startup caused by temporary malfunctions.

The vehicle control device disclosed herein is a vehicle control device that controls a vehicle that uses electric power at least as part of its driving source, and includes a discharge control unit that, in a drive circuit having a motor and a capacitor, performs active discharge by flowing a current through the d-axis of the motor to discharge the capacitor when the system is shut down, a judgment unit that judges whether or not to allow the system to start up at the next system startup , and a discharge circuit that performs passive discharge by discharging the capacitor by power consumption in an internal circuit consisting of the capacitor and a discharge resistor , and when the discharge control unit detects a discharge abnormality in the active discharge, it stores a record of the discharge abnormality in a memory unit, and when the system is next started up , if a record of the discharge abnormality has not been stored , the judgment unit allows the system to start up, and when the system is next started up, if a record of the discharge abnormality has been stored, it judges whether or not the voltage of the capacitor is below a threshold, and when the result of the judgment is that the voltage of the capacitor is below the threshold, it allows the system to start up, and when the result of the judgment is that the voltage of the capacitor exceeds the threshold, it does not allow the system to start up .

The vehicle control device disclosed herein can prevent temporary malfunctions from restricting system startup.

FIG. 1 is a diagram illustrating an example of a configuration of a drive system according to an embodiment. FIG. 2 is a block diagram illustrating an example of a hardware configuration of the hybrid control ECU together with a peripheral configuration according to the embodiment. FIG. 3A is a diagram illustrating an example of an operation performed by the hybrid control ECU according to the embodiment when active discharge is normally performed. FIG. 3B is a diagram illustrating an example of an operation performed by the hybrid control ECU according to the embodiment when a discharge abnormality occurs during active discharge. FIG. 3C is a diagram illustrating another example of an operation performed by the hybrid control ECU according to the embodiment when a discharge abnormality occurs during active discharge. FIG. 4 is a flowchart illustrating an example of a procedure of a process performed by the hybrid control ECU according to the embodiment.

Below, an embodiment of a vehicle control device according to the present disclosure will be described with reference to the drawings.

(Example of drive system configuration)
1 is a diagram showing an example of the configuration of a drive system 1 according to an embodiment. The drive system 1 according to the embodiment is mounted on a vehicle such as a hybrid electric vehicle (HEV) that uses electric power from a battery and power from an internal combustion engine as drive sources, and supplies power to the vehicle.

As shown in FIG. 1, the drive system 1 includes a generator 11, a motor 12, a power control device 20, a battery 30, a DC/AC converter 40, and a hybrid control ECU (Electronic Control Unit) 50.

The generator 11 and the motor 12 are both three-phase AC motors that supply three-phase AC drive current: U-phase, V-phase, and W-phase.

The generator 11 is connected to an internal combustion engine, such as an engine (not shown), of the vehicle, and is configured as a motor generator that mainly operates as a generator. The generator 11 converts at least a portion of the driving force generated by the internal combustion engine into electric power. The electric power converted by the generator 11 is used to charge the battery 30 or drive the motor 12.

The motor 12 is driven by electricity from a generator 11 that generates electricity using power from the internal combustion engine, and is configured as a motor generator that mainly outputs power for driving and regenerative braking force. In other words, the vehicle runs solely on power from the motor 12. It is also possible to charge the battery 30 using the regenerative braking force output from the motor 12.

The power control device 20 is interposed between the generator 11 and the motor 12 and the battery 30, and is configured as a PCU (Power Control Unit) or the like that controls the power from the drive source.

The power control device 20 includes an inverter 21, a boost converter 22, a step-down converter 23, a DC/DC converter 24, a motor generator (MG) ECU 25, a discharge resistor 261, a smoothing capacitor 262, a filter capacitor 263, current sensors 211 and 212, and voltage sensors 265a to 265c.

The inverter 21 includes a plurality of switching elements 213a to 213f that drive the generator 11, and a plurality of switching elements 214a to 214f that drive the motor 12. Each of these switching elements 213a to 213f, 214a to 214f includes a transistor such as an insulated gate bipolar transistor (IGBT) and a diode connected in parallel in the reverse direction to the transistor.

Each transistor is paired in pairs, one on the source side and the other on the sink side of the high-voltage power line and the negative power line. Each of the connection points between the two transistors in a pair is electrically connected to each of the three-phase coils of the generator 11 or the motor 12, the U-phase, V-phase, and W-phase.

The boost converter 22 includes multiple switching elements 221a and 221b, and boosts the power from the battery 30. The switching elements 221a and 221b of the boost converter 22 also each include a transistor such as an IGBT and a diode connected in parallel to the transistor in the reverse direction.

The step-down converter 23 is, for example, a reactor, and reduces the power from the motor 12, etc.

One end of the reactor of the step-down converter 23 is electrically connected to the positive power line. The other end of the reactor is electrically connected to the emitter of one of the transistors of the switching elements 221a and 221b and the collector of the other transistor. The collector of the one transistor is electrically connected to the high-voltage power line. The emitter of the other transistor is electrically connected to the negative power line.

A smoothing capacitor 262 is interposed on the inverter 21 side of the boost converter 22. The positive terminal of the smoothing capacitor 262 is electrically connected to the collector of one of the transistors of the boost converter 22 via a high-voltage power line. The negative terminal of the smoothing capacitor 262 is electrically connected to the emitter of the other transistor of the boost converter 22 via the negative power line.

As a result, the voltage boosted by the step-down converter 23 is smoothed by the smoothing capacitor 262.

The discharge resistor 261 is provided in association with the smoothing capacitor 262 and consumes internal power to discharge the charge stored in the smoothing capacitor 262, for example, after the vehicle ignition power is turned off.

The configuration including the smoothing capacitor 262 and the discharge resistor 261 is sometimes referred to as the discharge circuit 2.

A filter capacitor 263 is provided on the battery 30 side of the boost converter 22 and the step-down converter 23. The positive terminal of the filter capacitor 263 is electrically connected to one end of the reactor of the step-down converter 23 via the positive power line. The negative terminal of the filter capacitor 263 is electrically connected to the negative power line.

As a result, the voltage on the battery 30 side of the boost converter 22, i.e., the voltage applied to the boost converter 22, is smoothed by the filter capacitor 263.

The configuration including the generator 11, motor 12, inverter 21, boost converter 22, step-down converter 23, discharge resistor 261, smoothing capacitor 262, and filter capacitor 263 may also be referred to as drive circuit 3. The drive circuit 3 may also include current sensors 211, 212, and voltage sensors 265a to 265c.

The battery 30 is, for example, a lithium ion secondary battery or a nickel-metal hydride secondary battery, and is capable of receiving power from the generator 11 and the motor 12, storing the power, and also capable of supplying power to the generator 11 and the motor 12.

Current sensors 211, 212 are provided between the generator 11 and the inverter 21, and between the motor 12 and the inverter 21, respectively. The current sensors 211, 212 detect the currents flowing through the generator 11 and the motor 12, respectively.

A voltage sensor 265a is provided between the terminals of the smoothing capacitor 262. The voltage sensor 265a detects the terminal voltage VH of the smoothing capacitor 262. This terminal voltage VH of the smoothing capacitor 262 corresponds to the voltage after boosting by the boost converter 22.

A voltage sensor 265b is provided between the terminals of the filter capacitor 263. The voltage sensor 265b detects the terminal voltage VL of the filter capacitor 263. This terminal voltage VL of the filter capacitor 263 corresponds to the voltage before being boosted by the boost converter 22.

A voltage sensor 265c is provided between the terminals of the battery 30. The voltage sensor 265c detects the terminal voltage of the battery 30, that is, the battery voltage VB applied from the battery 30 to the boost converter 22.

The DC/DC converter 24 is connected to the output side of the battery 30 and converts the direct current (DC) voltage from the battery 30 into the operating voltage of various low-voltage devices such as the auxiliary battery. In other words, the DC/DC converter 24 steps down the high voltage from the battery 30 and supplies it to various low-voltage devices such as the auxiliary battery.

The MG-ECU 25 is configured as a computer equipped with, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory), and is an electronic control unit that controls each part of the power control device 20, such as the inverter 21, the boost converter 22, the step-down converter 23, and the DC/DC converter 24.

More specifically, the MG-ECU 25 receives command signals and the like from the hybrid control ECU 50 and controls the on/off of each transistor included in the inverter 21 and the boost converter 22. The MG-ECU 25 also obtains the detection results of the current sensors 211, 212 and the voltage sensors 265a to 265c and outputs them to the hybrid control ECU 50. When the MG-ECU 25 detects an abnormality in any part of the power control device 20, including the transistors, it outputs an abnormality signal to the hybrid control ECU 50.

The DC/AC converter 40 is connected between the DC/DC converter 24 and the battery 30, and converts the direct current power from the battery 30 into alternating current (AC) power, which is then output, for example, to the vehicle interior. This makes it possible to use various devices, such as home appliances, that run on AC power, inside the vehicle.

The hybrid control ECU (HEV-ECU) 50, which serves as a vehicle control device, is an electronic control unit that controls multiple drive sources, such as the power of the battery 30 and the power of the internal combustion engine, and is configured as a computer equipped with a CPU, ROM, RAM, etc.

In other words, the HEV-ECU 50 performs control such that, for example, when the vehicle starts and at low speeds where the internal combustion engine is inefficient, the vehicle runs solely on power from the motor 12, and when accelerating rapidly, the driving force from both the internal combustion engine and the motor 12 is used to obtain high acceleration force.

When the system is shut down, for example when the vehicle ignition power is turned off, the HEV-ECU 50 outputs a command signal to the MG-ECU 25 of the power control device 20 to rapidly discharge the charge accumulated in the smoothing capacitor 262. At this time, the HEV-ECU 50 monitors, for example via the MG-ECU 25, whether the smoothing capacitor 262 is being discharged normally.

The HEV-ECU 50 also determines whether to allow the system to start up the next time the system is started, such as when the ignition power is turned on again, depending on whether the smoothing capacitor 262 is discharging normally, etc.

(Example of the configuration of the hybrid control ECU)
Next, a configuration example of the HEV-ECU 50 according to the embodiment will be described with reference to Fig. 2. Fig. 2 is a block diagram showing an example of a hardware configuration of the HEV-ECU 50 according to the embodiment together with a peripheral configuration.

As shown in FIG. 2, the HEV-ECU 50 has, as functional units, an input/output unit 51, a discharge control unit 52, a determination unit 53, a warning generation unit 54, and a memory unit 55. These functional units are realized by the CPU of the HEV-ECU 50 expanding a control program stored in the ROM, for example, into the RAM and executing it, and by the ROM and RAM operating under the control of the CPU that executes the control program.

The input/output unit 51 is configured to be able to transmit and receive various signals between the HEV-ECU 50 and peripheral components such as the MG-ECU 25 provided in the power control device 20 and the display control ECU 60 that controls the display device 610.

For example, the input/output unit 51 acquires from the MG-ECU 25 the detection results of the current value or voltage value by the current sensors 211, 212 and voltage sensors 265a to 265c provided in the power control device 20. The input/output unit 51 also acquires from the MG-ECU 25 an abnormality signal indicating that some abnormality has occurred in the power control device 20. The input/output unit 51 also outputs command signals generated by the discharge control unit 52, the determination unit 53, etc. to the MG-ECU 25.

For example, when the input/output unit 51 receives an abnormality signal from the MG-ECU 25 indicating that an abnormality has occurred in the discharge of the smoothing capacitor 262 when the system is shut down, the input/output unit 51 outputs the warning generated by the warning generation unit 54 to the display control ECU 60.

The discharge control unit 52 generates a command signal for the MG-ECU 25 when the system is shut down, and rapidly discharges the charge accumulated in the smoothing capacitor 262. That is, when the MG-ECU 25 receives a command signal from the discharge control unit 52 via the input/output unit 51, it causes a current to flow through the d-axis of the motor 12 to consume power, thereby discharging the smoothing capacitor 262.

Here, motor 12 has a d-axis (direct axis) that is in the same direction as the magnetic field lines that run from the north pole to the south pole of the permanent magnet that motor 12 has, and a q-axis (quadrature axis) that is perpendicular to the d-axis.

Under normal circumstances, torque can be generated by passing a current through the q-axis of the motor 12, causing the motor 12 to rotate. On the other hand, when a current is passed through the d-axis of the motor 12, no torque is generated, and the electric energy is converted into thermal energy in the electromagnet coil of the motor 12, consuming power and allowing the smoothing capacitor 262 to be discharged.

This rapid discharge of the smoothing capacitor 262 by passing a current through the d-axis of the motor 12 is also called active discharge. Such active discharge is performed so that, for example, maintenance workers can access high-voltage parts such as the smoothing capacitor 262 after the system is shut down without risking electric shock.

As described above, the power control device 20 includes a discharge circuit 2 that includes a smoothing capacitor 262 and a discharge resistor 261. Therefore, if active discharge is not performed normally due to some malfunction, power continues to be consumed in the discharge circuit 2 by the discharge resistor 261 even after the system is shut down, making it possible to gradually discharge the smoothing capacitor 262.

Discharging the smoothing capacitor 262 by consuming power in the discharge circuit 2 in this way is also called passive discharging. However, while active discharging can discharge the smoothing capacitor 262 in, for example, a few seconds, passive discharging takes, for example, several minutes to discharge the smoothing capacitor 262.

The MG-ECU 25 can detect that some malfunction has occurred in the active discharge, for example, when the voltage of the smoothing capacitor 262 does not become equal to or lower than a predetermined threshold within a predetermined time during the active discharge. The voltage of the smoothing capacitor 262 can be known, for example, from the detection result of the voltage sensor 262a that detects the inter-terminal voltage VH of the smoothing capacitor 262.

In addition, if any malfunction occurs in the active discharge, the HEV-ECU 50 receives an abnormality signal from the MG-ECU 25 via the input/output unit 51, as described above.

When the discharge control unit 52 receives an abnormality signal from the MG-ECU 25 indicating that a discharge abnormality has occurred during active discharge, it stores a record of the discharge abnormality during active discharge in the memory unit 55. Note that, because such a discharge abnormality determination is performed, for example, after the system is shut down, the record of the discharge abnormality is stored in more detail in a non-volatile memory such as a ROM.

However, if the vehicle is traveling at a certain speed or above when a command signal for active discharge is received, and it is known that active discharge is not or cannot be performed due to control reasons, such an abnormality determination will not be made. In this case, the MG-ECU 25 will not output an abnormality signal in the first place, or even if the MG-ECU 25 outputs an abnormality signal, the discharge control unit 52 will not record it in the memory unit 55, and a discharge abnormality will not be confirmed.

The determination unit 53 refers to the memory unit 55 the next time the system is started to check whether a record of a discharge abnormality during active discharge has been stored. If there is no record of a discharge abnormality remaining in the memory unit 55, the determination unit 53 allows the system to start.

On the other hand, if a discharge abnormality is recorded in the memory unit 55, the determination unit 53 outputs a command signal to the MG-ECU 25 via the input/output unit 51 to read the detection result of the voltage sensor 262a of the power control device 20. The determination unit 53 determines whether or not to permit the system to start based on the detection result of the voltage sensor 262a.

When the warning generation unit 54 receives an abnormality signal indicating a discharge abnormality in active discharge from the MG-ECU 25, it generates a warning indicating that a discharge abnormality has occurred in active discharge. Note that when an abnormality signal other than the above-mentioned discharge abnormality is received from the power control device 20, the warning generation unit 54 may generate a warning about that abnormality.

The display control ECU 60 is an electronic control unit that controls a display device 610 provided, for example, in the passenger compartment of the vehicle, and is configured as a computer equipped with a CPU, ROM, RAM, etc. The display control ECU 60 causes the display device 610 to perform various displays based on command signals from the HEV-ECU 50.

As an example, when the display control ECU 60 receives a warning generated by the warning generation unit 54 from the input/output unit 51, it causes the display device 610 to display a warning that an abnormality, such as a discharge abnormality during active discharge, has occurred in the power control device 20.

The display device 610 is, for example, a liquid crystal display (LCD) or an organic electroluminescent display (OELD), and displays various information, including the above warnings, to the vehicle user.

The memory unit 55 stores the control programs executed by the CPU of the HEV-ECU 50, and various control parameters necessary for the operation of the HEV-ECU 50. Furthermore, when an abnormality signal indicating a discharge abnormality in active discharge is received from the MG-ECU 25, the memory unit 55 stores a record of this discharge abnormality as described above. The record of the discharge abnormality is held in the memory unit 55 until it is erased by a maintenance worker, for example, by connecting a console to the HEV-ECU 50.

(Example of operation of hybrid control ECU)
Next, a detailed operation example of the HEV-ECU 50 of the embodiment will be described with reference to FIGS. 3A to 3C.

Figure 3A is a diagram illustrating an example of the operation performed by the HEV-ECU 50 according to the embodiment when active discharge is performed normally.

As shown in FIG. 3A, when the system is shut down, for example when the ignition power is turned off, the discharge control unit 52 of the HEV-ECU 50 outputs a command signal to the MG-ECU 25 via the input/output unit 51 to perform active discharge. The MG-ECU 25 performs active discharge by passing a current through the d-axis of the motor 12 in accordance with the command signal from the HEV-ECU 50.

As a result, as shown by the voltage curve VHa due to active discharge in the figure, the terminal voltage VH of the smoothing capacitor 262 drops rapidly and falls below a predetermined threshold TH, which is detected by, for example, the voltage sensor 265a.

Then, the next time the system is started, such as when the ignition power is turned on, the determination unit 53 of the HEV-ECU 50 checks whether a record of a discharge abnormality during active discharge has been stored in the memory unit 55. In the example of FIG. 3A, the previous time the system was shut down, active discharge was performed normally, so no record of a discharge abnormality has been stored.

In this case, the HEV-ECU 50 allows the system to start up. As a result, the power output from the battery 30 and boosted by the boost converter 22 is supplied to the smoothing capacitor 262, and the generator 11 and the motor 12 start to operate. Therefore, as shown by the voltage curve VHc due to the boost of the boost converter 22 in the figure, the voltage between the terminals of the smoothing capacitor 262, VH, rises rapidly, which is detected by the voltage sensor 265a, etc.

Figure 3B is a diagram illustrating an example of the operation performed by the HEV-ECU 50 according to the embodiment when a discharge abnormality occurs during active discharge.

As shown in FIG. 3B, when the system is shut down, the discharge control unit 52 of the HEV-ECU 50 outputs a command signal to the MG-ECU 25 to perform active discharge, and the MG-ECU 25 passes current through the d-axis of the motor 12 to perform active discharge.

At this time, it is assumed that some malfunction has occurred in the power control device 20, and active discharge has not been performed normally. In this case, as shown by the voltage curve VHa' due to active discharge in the figure, a rapid drop in the terminal voltage VH of the smoothing capacitor 262 is not detected.

Based on the above detection result of the voltage sensor 265a, the MG-ECU 25 determines that a discharge abnormality has occurred during active discharge and outputs an abnormality signal to the HEV-ECU 50.

When the discharge control unit 52 receives an abnormality signal from the MG-ECU 25, the discharge control unit 52 stores in the memory unit 55 a record that a discharge abnormality has occurred during active discharge. In addition, the warning generation unit 54 generates a warning that a discharge abnormality has occurred and outputs it to the display control ECU 60 via the input/output unit 51. The display control ECU 60 displays the received warning on the display device 610.

In the example of FIG. 3B, it is assumed that passive discharge was normally performed by the discharge circuit 2 after the system was shut down. In other words, it is assumed that power was consumed by the discharge resistor 261 of the discharge circuit 2, and the smoothing capacitor 262 was discharged. As a result, as shown by the voltage curve VHp due to passive discharge in the figure, the terminal voltage VH of the smoothing capacitor 262 gradually decreases and becomes equal to or lower than the predetermined threshold value TH.

Then, when the system is next started, the determination unit 53 of the HEV-ECU 50 refers to the memory unit 55, and in the example of FIG. 3B, a record of a discharge anomaly during active discharge is stored.

Then, the determination unit 53 outputs a command signal to the MG-ECU 25 via the input/output unit 51 to read the detection result of the voltage sensor 265a. The MG-ECU 25 obtains the detection result of the voltage sensor 265a in accordance with the command signal from the HEV-ECU 50 and outputs it to the HEV-ECU 50.

Based on the detection result of the voltage sensor 265a, the determination unit 53 determines whether the terminal voltage VH of the smoothing capacitor 262 is equal to or lower than the threshold value TH. In the example of FIG. 3B, since passive discharge was performed normally after the system was shut down, it is detected that the terminal voltage VH of the smoothing capacitor 262 is equal to or lower than the threshold value TH.

In this case, the determination unit 53 allows the system to start up. As a result, the smoothing capacitor 262 stores electricity, and the terminal voltage VH of the smoothing capacitor 262 rises rapidly, as shown by the voltage curve VHc due to the boost of the boost converter 22 in the figure, which is detected by the voltage sensor 265a, etc.

Figure 3C is a diagram illustrating another example of the operation performed by the HEV-ECU 50 according to the embodiment when a discharge abnormality occurs during active discharge.

As shown in FIG. 3A, when the system is shut down, the discharge control unit 52 of the HEV-ECU 50 outputs a command signal to the MG-ECU 25 to perform active discharge, and the MG-ECU 25 passes current through the d-axis of the motor 12 to perform active discharge.

At this time, in the example of FIG. 3C, some malfunction occurs in the power control device 20, and as shown by the voltage curve VHa' due to active discharge in the figure, the terminal voltage VH of the smoothing capacitor 262 does not become equal to or lower than the threshold value TH.

The MG-ECU 25 outputs an abnormality signal to the HEV-ECU 50, and the discharge control unit 52 of the HEV-ECU 50 stores a record of the discharge abnormality in the memory unit 55. The warning generation unit 54 generates a warning of the discharge abnormality, and the warning is displayed on the display device 610.

In the example of FIG. 3C, after the system is shut down, passive discharge by the discharge circuit 2 is not performed normally, and the terminal voltage VH of the smoothing capacitor 262 remains high, as shown by the voltage curve VHp' due to passive discharge in the figure.

Then, when the determination unit 53 of the HEV-ECU 50 refers to the memory unit 55 the next time the system is started, it finds that a record of a discharge anomaly during active discharge has been stored, even in the example of FIG. 3C. The determination unit 53 outputs the detection result of the voltage sensor 265a to the MG-ECU 25.

The determination unit 53 also determines that the terminal voltage VH of the smoothing capacitor 262 exceeds the threshold TH based on the detection result of the voltage sensor 265a. In this case, the determination unit 53 does not allow the system to start up.

Here, a temporary malfunction may be the cause of an active discharge abnormality. A temporary malfunction may occur when a temporary disconnection occurs in the output line that outputs the active discharge command signal from the HEV-ECU 50 to the MG-ECU 25, for example due to a poor contact in a connector. Alternatively, the power control device 20 may be in a reset state, for example, and may have temporarily transitioned to a state in which it cannot receive the active discharge command signal. Another possible cause may be when the motor 12 is rotated from outside by the rotation of the wheels, for example, while the vehicle is on a slope, and the power control device 20 does not receive the active discharge command signal.

When the system is next started, even if a record of a discharge anomaly is stored, if the voltage of the smoothing capacitor 262 is equal to or lower than the threshold value TH, the determination unit 53 allows the system to start as described above. This prevents the system from being prohibited from starting even in cases where active discharge is caused by a temporary malfunction.

However, if the voltage of the smoothing capacitor 262 remains greater than the threshold value TH even at the next system startup, for example because the power control device 20 remains in a persistently faulty state, the determination unit 53 will not allow the system to start, as described above. This ensures the safety of the vehicle user and maintenance workers, etc.

On the other hand, even if some kind of non-primary failure actually occurs in the mechanism related to the active discharge of the power control device 20, the system can be allowed to start up if the passive discharge is performed normally. However, even in this case, for example, a warning is repeatedly displayed when the system is started up, so that the user of the vehicle can become aware of the failure of the power control device 20.

(Example of processing by the hybrid control ECU)
Next, an example of processing by the HEV-ECU 50 according to the embodiment will be described with reference to Fig. 4. Fig. 4 is a flow chart showing an example of a procedure of processing by the HEV-ECU 50 according to the embodiment.

As shown in FIG. 4, the determination unit 53 of the HEV-ECU 50 waits for a system startup operation, such as turning on the ignition power (step S101). The determination unit 53 waits until the system startup operation is performed (step S101: No).

When the system is started (step S101: Yes), the determination unit 53 refers to the memory unit 55 to check whether a record of a discharge abnormality during active discharge has been stored (step S102).

If a discharge abnormality is recorded (step S102: Yes), the determination unit 53 instructs the MG-ECU 25 to read the detection result of the voltage sensor 265a (step S103).

When the detection result of the voltage sensor 265a is output from the MG-ECU 25, the determination unit 53 determines whether the voltage of the smoothing capacitor 262 is equal to or lower than the threshold value TH based on the detection result of the voltage sensor 265a (step S104).

If the voltage of the smoothing capacitor 262 is greater than the threshold value TH (step S104: No), the determination unit 53 ends the process without allowing the system to start (step S111).

If the voltage of the smoothing capacitor 262 is equal to or lower than the threshold value TH (step S104: Yes), the determination unit 53 allows the system to start up (step S105).

Also, when the memory unit 55 is consulted and no record of a discharge abnormality remains (step S102: No), the judgment unit 53 allows the system to start up without performing the processes of steps S103, S104, S111, etc. (step S105).

When the system is started, the discharge control unit 52 of the HEV-ECU 50 waits for an operation to shut down the system, such as turning off the ignition power (step S106). The discharge control unit 52 waits until an operation to shut down the system is performed (step S106: No).

When the system is shut down (step S106: Yes), the discharge control unit 52 instructs the MG-ECU 25 to perform active discharge (step S107). The discharge control unit 52 also determines whether the active discharge has ended normally (step S108).

When an abnormality signal is output from the MG-ECU 25 and active discharge is not performed normally (step S108: No), the discharge control unit 52 stores a record of the discharge abnormality during active discharge in the memory unit 55 (step S110). In addition, the warning generation unit 54 of the HEV-ECU 50 generates a warning of the discharge abnormality during active discharge and outputs it to the display control ECU 60 via the input/output unit 51 (step S110). The output warning is displayed on the display device 610 under the control of the display control ECU 60.

If the active discharge ends normally without an abnormality signal being output from the MG-ECU 25 (step S108: Yes), the processing of steps S109 and S110 is skipped.

This completes the processing by the HEV-ECU 50 in this embodiment.

(Summary)
In vehicles such as hybrid vehicles that use electric power at least as part of the drive source, active discharge is performed to discharge the charge accumulated in smoothing capacitors, etc., when the system is shut down. This makes it possible to prevent vehicle users and maintenance workers from receiving electric shocks by accessing high-voltage parts.

If a discharge abnormality occurs during active discharge, such as the voltage of the smoothing capacitor not dropping normally, a record of the discharge abnormality is stored in a memory unit, etc. Furthermore, the next time the system is started, the fail-safe function will prohibit the system from starting up. The record of the discharge abnormality is kept in the memory unit until it is erased by a maintenance worker, etc.

Here, even if a discharge abnormality is detected, there may be cases where no malfunction is found in the drive circuit or the like. It is assumed that such a discharge abnormality is due to a temporary malfunction, such as a temporary poor contact in a connector or a temporary inability to respond on the power control device 20 side. However, if the fail-safe function is activated even when a discharge abnormality occurs due to a temporary malfunction, the system cannot be started up until, for example, a maintenance worker erases the record of the discharge abnormality, which may lead to a breakdown on the road.

According to the embodiment of the HEV-ECU 50, when the system is next started, if the voltage of the smoothing capacitor 262 is equal to or lower than the threshold value, the system is permitted to start even if a record of a discharge abnormality during active discharge has been stored. This makes it possible to prevent restrictions on system start-up due to a temporary malfunction, and therefore makes it possible to prevent the vehicle from breaking down on the road.

According to the embodiment of the HEV-ECU 50, the next time the system is started, if a record of a discharge abnormality during active discharge has been stored and the voltage of the smoothing capacitor 262 is greater than the threshold value, the system will not be allowed to start. This ensures the safety of vehicle users and maintenance workers.

According to the embodiment of the HEV-ECU 50, when the discharge control unit 52 detects a discharge abnormality during active discharge, a warning is generated to be displayed on the display device 610 provided in the vehicle. This makes it possible to inform the user of the vehicle that there is a possibility that some kind of malfunction has actually occurred in the power control device 20, etc.

In the above embodiment, the power control device 20 is provided with a plurality of voltage sensors 265a to 265c, and the determination as to whether or not to start the system is based on the detection result of the voltage sensor 265a that detects the voltage of the smoothing capacitor 262. However, a predetermined threshold may be set for each of the plurality of voltage sensors 265a to 265c, and the system may be permitted to start if the detection results of at least some of the voltage sensors are below the threshold, or if the detection results of all of these voltage sensors are below the threshold.

In the above embodiment, the HEV-ECU 50 that controls the vehicle, which is a hybrid vehicle, determines whether or not to start the system based on whether or not a discharge abnormality has been recorded and the actual voltage of the smoothing capacitor 262. However, the above configuration of the embodiment can also be applied to a vehicle control device that controls a vehicle that is driven exclusively by electricity, such as an electric vehicle (EV).

(Additional Note)
Preferred aspects of the present invention will be described below.

(Appendix 1)
According to one aspect of the present invention,
A vehicle control device that controls a vehicle that uses electric power at least as part of a driving source,
a discharge control unit for causing a current to flow through a d-axis of the motor to discharge the capacitor when the system is shut down, in a drive circuit having a motor and a capacitor;
a determination unit that determines whether or not to permit system startup at the next system startup,
The discharge control unit is
When a discharge abnormality is detected in the active discharge, a record of the discharge abnormality is stored in a memory unit;
The determination unit is
When the voltage of the capacitor is equal to or lower than a threshold value at the next system startup, the system startup is permitted even if the record of the discharge abnormality is stored.
A vehicle control device is provided.

(Appendix 2)
In the vehicle control device described in Supplementary Note 1,
The determination unit is
At the next system startup, if the record of the discharge abnormality is stored and the voltage of the capacitor is greater than the threshold value, startup of the system is not permitted.

(Appendix 3)
In the vehicle control device according to the above-mentioned supplementary note 1 or supplementary note 2,
The vehicle further includes a warning generating unit that generates a warning to be displayed on a display device provided in the vehicle when the discharge control unit detects a discharge abnormality during the active discharge.

(Appendix 4)
In the vehicle control device according to any one of Supplementary Note 1 to Supplementary Note 3,
The drive circuit includes:
The power supply further includes a discharge circuit that performs passive discharge by discharging the capacitor through power consumption in an internal circuit even after the system has been shut down.

(Appendix 5)
In the vehicle control device according to any one of Supplementary Note 1 to Supplementary Note 4,
The drive circuit includes:
The capacitor includes at least a voltage sensor for detecting a voltage of the capacitor.
The determination unit is
When the system is next started, if the discharge abnormality is recorded, it is determined whether or not to permit the system to start based on the detection result of the voltage sensor.

(Appendix 6)
In the vehicle control device according to any one of Supplementary Note 1 to Supplementary Note 4,
The drive circuit includes:
The power supply further includes a plurality of voltage sensors including a voltage sensor for detecting a voltage of the capacitor,
The determination unit is
When the discharge abnormality record is stored at the next system startup, if all detection results of the multiple voltage sensors are equal to or lower than the threshold value, the system is permitted to start even if the discharge abnormality record is stored.

1 Drive system 2 Discharge circuit 3 Drive circuit 11 Generator 12 Motor 20 Power control device 25 MG-ECU
30 Battery 50 Hybrid control ECU (HEV-ECU)
51 Input/Output Unit 52 Discharge Control Unit 53 Determination Unit 54 Warning Generation Unit 55 Storage Unit 60 Display Control ECU
261 Discharge resistor 262 Smoothing capacitors 265a to 265c Voltage sensor 610 Display device

Claims (1)

A vehicle control device that controls a vehicle that uses electric power at least as part of a driving source,
a discharge control unit for causing a current to flow through a d-axis of the motor to discharge the capacitor when the system is shut down, in a drive circuit having a motor and a capacitor;
a determination unit that determines whether or not to permit system startup at the next system startup;
a discharge circuit that performs passive discharge by discharging the capacitor through power consumption in an internal circuit that is composed of the capacitor and a discharge resistor ,
The discharge control unit is
When a discharge abnormality is detected in the active discharge, a record of the discharge abnormality is stored in a memory unit;
The determination unit is
When the discharge abnormality is not recorded at the next system startup , the system startup is permitted.
When the system is started next time, if the discharge abnormality is recorded, it is determined whether the voltage of the capacitor is equal to or lower than a threshold value.
permitting the system to start up when the voltage of the capacitor is equal to or lower than a threshold value as a result of the determination;
If the result of the determination is that the voltage of the capacitor exceeds a threshold value, startup of the system is not permitted.
Vehicle control device.

Images