JP7797342B2 - Vehicle drive control device and control method for vehicle drive control device - Google Patents

Description

The present invention relates to a vehicle drive control device and a control method for a vehicle drive control device.

2. Description of the Related Art Conventionally, there is known a technique relating to a vehicle drive control device that is mounted on a vehicle and driven by a motor.
For example, Patent Document 1 describes a motor driver that executes control (three-phase short-circuit control) to short-circuit the AC output terminals of the motor driver (inverter) when an abnormality occurs. It also discloses that when the contactor is turned off while the motor is being driven, if the motor induced voltage rises, various components such as the control circuit are activated to perform control so that the withstand voltage is not exceeded.

JP 2014-183702 A

However, when the switching elements of the motor driver are turned off to terminate control of shorting the AC output terminals of the motor driver (three-phase short-circuit control), a surge voltage is generated. If the surge voltage is greater than the withstand voltage of the switching elements, the switching elements may be damaged.
An object of the present invention is to suppress surge voltages that occur when switching elements are turned off during execution of three-phase short-circuit control.

One aspect of the present invention is a vehicle drive control device comprising: a motor driver arranged between a power source and a three-phase motor that drives a vehicle, the motor driver being composed of switching elements and controlling the three-phase motor; and a control device that controls the motor driver, wherein the control device comprises: a current acquisition unit that acquires current values flowing in each coil of the three-phase motor; a speed acquisition unit that acquires the rotational speed of the three-phase motor; a first release processing unit that, when the motor driver is performing three-phase short circuit control and the rotational speed is below a predetermined threshold, turns off a negative-side switching element corresponding to one of the current values flowing in the three coils of the three-phase motor when the current value flowing in the one coil is below a first threshold greater than zero and above zero; and a second release processing unit that turns off the negative-side switching elements corresponding to each of the two coils when the current values flowing in the two coils other than the one coil are below a second threshold, wherein the second threshold is set to a value below a predetermined value and greater than the first threshold .

This invention makes it possible to suppress surge voltages that occur when switching elements are turned off during three-phase short-circuit control.

FIG. 1 is a diagram showing an example of the configuration of a vehicle drive control device. FIG. 2 is a diagram showing an example of the configuration of a control device. FIG. 2 is a diagram showing an example of the configuration of a speed detection circuit. 6 is a graph showing an example of the operation of the control device. 10 is a flowchart showing an example of processing by a control device.

Embodiments of the present invention will be described below with reference to the drawings.

[1. Configuration of vehicle drive control device]
First, the configuration of a vehicle drive control device 100 will be described with reference to Fig. 1. Fig. 1 is a diagram showing an example of the configuration of a vehicle drive control device 100.
As shown in FIG. 1, the vehicle drive control device 100 includes a motor drive circuit 1, a driver drive circuit 2, and a control device 3.
The motor drive circuit 1 is a circuit for driving a three-phase motor 15 and includes a battery 11 , a contactor 12 , a capacitor 13 , and a motor driver 14 .

The battery 11 supplies power to a three-phase motor 15 via a motor driver 14 .
The battery 11 corresponds to an example of a "power source."
The contactor 12 is disposed between the battery 11 and the motor driver 14. The contactor 12 is turned off when an abnormality occurs in the vehicle. When the contactor 12 is turned off, the supply of power from the battery 11 to the motor driver 14 is cut off.
The contactor 12 corresponds to an example of a "switch."

Capacitor 13 is disposed between the positive terminal 14P and the negative terminal 14M of motor driver 14. When contactor 12 is turned off, capacitor 13 applies a capacitor voltage between the positive terminal 14P and the negative terminal 14M of motor driver 14.

The motor driver 14 is composed of MOSFETs (Metal-Oxide-Semiconductor Field Effect Transistors) 14U1, 14U2, 14V1, 14V2, 14W1, and 14W2. Each of these six MOSFETs is turned on and off in accordance with instructions from the driver drive circuit 2.
The MOSFET corresponds to an example of a "switching element."
The motor driver 14 functions as an "inverter."

The three-phase motor 15 is, for example, a three-phase synchronous motor using a permanent magnet. As shown in Fig. 1, the three-phase motor 15 includes a motor coil 15U, a motor coil 15V, and a motor coil 15W.
The three-phase motor 15 drives the vehicle with power supplied from the battery 11 via the motor driver 14. The vehicle is, for example, a motorbike (motorcycle).

In this embodiment, the vehicle is described as a motorbike (two-wheeled motor vehicle), but is not limited to this. The vehicle may be, for example, a four-wheeled passenger car or a four-wheeled large vehicle. The vehicle may also be, for example, a work vehicle such as a tractor.

A current sensor SC is disposed between the motor driver 14 and the three-phase motor 15. The current sensor SC detects the current value flowing through each coil of the three-phase motor 15. That is, the current sensor SC detects the current value IU flowing through motor coil 15U, the current value IV flowing through motor coil 15V, and the current value IW flowing through motor coil 15W. The current sensor SC outputs the detected current values IU, IV, and IW to the control device 3.

The driver drive circuit 2 controls the motor driver 14 in accordance with instructions from the control device 3. That is, the driver drive circuit 2 controls the on/off of each of the six MOSFETs that make up the motor driver 14 in accordance with instructions from the control device 3.

The control device 3 controls the driver drive circuit 2 based on the current values IU, IV, and IW. When the contactor 12 is turned off, the control device 3 performs three-phase short-circuit control on the motor driver 14.
The three-phase short circuit control will be further explained with reference to FIG.

[2. Configuration of the control device]
Next, the configuration of the control device 3 will be described with reference to Fig. 2. Fig. 2 is a diagram showing an example of the configuration of the control device 3.
The control device 3 controls the three-phase motor 15 via the driver drive circuit 2 and the motor driver 14 based on the detection result of the current sensor SC.
The control device 3 is configured by, for example, an ECU (Electronic Control Unit), and includes a processor 31, a memory 32, and a speed detection circuit 33.
The speed detection circuit 33 detects the rotation speed RS of the three-phase motor 15 based on the current values IU, IV, and IW.
The speed detection circuit 33 constitutes a part of the "speed acquisition unit."
The speed detection circuit 33 will be further explained in the explanation of the speed acquisition unit 313, and further explained with reference to FIG.

Memory 32 is a storage device that non-volatilely stores programs, data, etc. executed by processor 31. Memory 32 is composed of a magnetic storage device, a semiconductor storage element such as flash ROM (Read Only Memory), or other types of non-volatile storage device. Memory 32 may also include RAM (Random Access Memory) that forms the work area of processor 31. Memory 32 stores data processed by control device 3 and control program 321 executed by processor 31.

The processor 31 may be configured as a single processor, or a plurality of processors may function as the processor 31. The processor 31 executes a control program 321 to control the three-phase motor 15 via the driver driving circuit 2 and the motor driver 14.
The control device 3 includes a short circuit control unit 311, a current acquisition unit 312, a speed acquisition unit 313, a first release processing unit 314, and a second release processing unit 315. Specifically, the processor 31 of the control device 3 executes a control program 321 to function as the short circuit control unit 311, the current acquisition unit 312, the speed acquisition unit 313, the first release processing unit 314, and the second release processing unit 315.

When the contactor 12 is off, the short circuit control unit 311 causes the motor driver 14 to execute three-phase short circuit control. The three-phase short circuit control is a control in which the short circuit control unit 311 turns off all of the MOSFETs on the positive side of the motor driver 14 and turns on all of the MOSFETs on the negative side of the motor driver 14.
The positive-side MOSFETs are MOSFET 14U1, MOSFET 14V1, and MOSFET 14W1 connected to the positive-side terminal 14P of the motor driver 14. The negative-side MOSFETs are MOSFET 14U2, MOSFET 14V2, and MOSFET 14W2 connected to the negative-side terminal 14M of the motor driver 14.

When the contactor 12 is off, the short-circuit control unit 311 causes the motor driver 14 to execute three-phase short-circuit control, thereby efficiently releasing the energy stored in the motor coils 15U, 15V, and 15W. As a result, the short-circuit control unit 311 can stop the three-phase motor 15 in a short period of time by executing three-phase short-circuit control.

The current acquisition unit 312 acquires the current values IU, IV, and IW from the current sensor SC. The current value IU is the value of the current flowing through the motor coil 15U. The current value IV is the value of the current flowing through the motor coil 15V. The current value IW is the value of the current flowing through the motor coil 15W.

The speed acquisition unit 313 acquires the rotation speed RS of the three-phase motor 15 from the speed detection circuit 33 .
The speed detection circuit 33 will be described with reference to FIG.

The first release processing unit 314 executes the following process when the rotation speed RS acquired by the speed acquisition unit 313 is equal to or less than the speed threshold value RTH while the motor driver 14 is executing three-phase short-circuit control. That is, when the current value flowing through one coil (e.g., motor coil 15U) of the current values IU, IV, and IW flowing through the three coils (15U, 15V, and 15W) of the three-phase motor 15 is equal to or less than a first threshold value TH1 that is greater than zero and equal to or greater than zero, the first release processing unit 314 turns off a negative-side MOSFET (e.g., MOSFET 14U2) corresponding to one coil (e.g., motor coil 15U).
The speed threshold RTH corresponds to an example of a "predetermined threshold."

Furthermore, after the rotation speed RS reaches or falls below the speed threshold RTH, the first release processing unit 314 turns off the negative-side MOSFET (e.g., MOSFET 14U2) corresponding to one coil (e.g., motor coil 15U) when the condition that the current value flowing through one of the current values IU, IV, and IW flowing through each coil of the three-phase motor 15 is equal to or less than a first threshold TH1 that is greater than zero and equal to or greater than zero is first satisfied.

In this embodiment, the case where the "one coil" is the motor coil 15U will be described. That is, the case where the first release processing unit 314 turns off the MOSFET 14U2 will be described. The MOSFET 14U2 corresponds to an example of a "negative-side switching element."
In this embodiment, the case where the "one coil" is motor coil 15U will be described, but the "one coil" may be motor coil 15V or motor coil 15W. For example, if the "one coil" is motor coil 15V, the "negative side switching element" is MOSFET 14V2. Also, for example, if the "one coil" is motor coil 15W, the "negative side switching element" is MOSFET 14W2.

The speed threshold RTH is, for example, 100 rpm. The larger the speed threshold RTH, the earlier the three-phase short circuit control can be terminated. The smaller the speed threshold RTH, the more the surge voltage generated when the negative-side MOSFET is turned off can be suppressed.
The first threshold TH1 is, for example, 0.1 A. The higher the control accuracy of the control device 3, the smaller the first threshold TH1 can be. The smaller the first threshold TH1, the more the surge voltage VS that occurs when the first release processing unit 314 turns off the negative-side MOSFET (e.g., MOSFET 14U2). Furthermore, the larger the first threshold TH1, the less the requirement for control accuracy of the control device 3 can be.

Furthermore, the first release processing unit 314 turns off the negative-side MOSFET (e.g., MOSFET 14U2) corresponding to one coil (e.g., motor coil 15U) when the current value flowing through one of the current values IU, IV, and IW is equal to or less than a first threshold value TH1 greater than zero and equal to or greater than zero for the first time. This allows the three-phase short circuit control to be terminated early. This also prevents the three-phase motor 15 from overheating due to the three-phase short circuit control.

Furthermore, when the current value (e.g., current values IV and IW) flowing through two of the three coils (e.g., motor coils 15V and 15W) excluding one coil (e.g., motor coil 15U) is less than or equal to the second threshold value TH2, the second release processing unit 315 turns off the negative-side MOSFETs (e.g., MOSFET 14V2 and MOSFET 14W2) corresponding to each of the two coils (e.g., motor coils 15V and 15W).

In this embodiment, the case where the "one coil" is motor coil 15U will be described. That is, the case where the second release processing unit 315 turns off MOSFET 14V2 and MOSFET 14W2 will be described. MOSFET 14V2 and MOSFET 14W2 correspond to an example of "negative-side switching elements corresponding to each of the two coils."

The second threshold TH2 is set to a value greater than the first threshold TH1. The second threshold TH2 is, for example, 0.3 A. The larger the second threshold TH2, the earlier the negative-side MOSFETs corresponding to each of the two coils (e.g., MOSFET 14V2 and MOSFET 14W2) can be turned off. This allows the three-phase short-circuit control to be terminated earlier. This makes it possible to suppress heating of the three-phase motor 15 that accompanies the three-phase short-circuit control. Furthermore, the smaller the second threshold TH2, the more the surge voltage that occurs when the negative-side MOSFETs (e.g., MOSFET 14V2 and MOSFET 14W2) are turned off can be suppressed.

[3. Configuration of Speed Detection Circuit]
Next, the configuration of the speed detection circuit 33 will be described with reference to Fig. 3. Fig. 3 is a diagram showing an example of the configuration of the speed detection circuit 33. The speed detection circuit 33 receives the current values IU, IV, and IW from the current sensor SC and outputs the rotation speed RS of the three-phase motor 15.
As shown in FIG. 3, the speed detection circuit 33 includes a zero time detection circuit 331 , a period calculation circuit 332 , and a rotation speed calculation circuit 333 .

The zero time detection circuit 331 receives the current values IU, IV, and IW from the current sensor SC and outputs the zero time TZ to the period calculation circuit 332. The zero time TZ is the time T at which each of the current values IU, IV, and IW becomes zero.
In this embodiment, a case will be described in which the zero time detection circuit 331 receives, for example, a current value IU from a current sensor SC and outputs the zero time TZ, which is the time at which the current value IU becomes zero, to the period calculation circuit 332.

The period calculation circuit 332 calculates the period TM of the current value IU based on the zero time TZ output from the zero time detection circuit 331. The period calculation circuit 332 calculates the difference ΔTZ between the current zero time TZ and the previous zero time TZ, and calculates twice the difference ΔTZ as the period TM, as shown in, for example, equation (1).
TM=ΔTZ×2 (1)

The rotation speed calculation circuit 333 calculates the rotation speed RS of the three-phase motor 15 based on the period TM output from the period calculation circuit 332. The rotation speed calculation circuit 333 calculates the rotation speed RS, for example, by the following equation (2).
RS=60×(1/TM) (2)
The period TM is expressed in units of seconds, for example. The rotation speed RS is expressed in units of rpm, for example. "60" is a conversion factor.
The rotation speed calculation circuit 333 outputs the rotation speed RS to the speed acquisition unit 313 .

In this way, the speed detection circuit 33 calculates the rotation speed RS based on the current values IU, IV, and IW from the current sensor SC, so that the rotation speed RS can be calculated in a short time. For example, the speed detection circuit 33 can calculate the rotation speed RS in a short time compared to a case where an angle sensor that detects the rotation angle of the three-phase motor 15 is provided and the speed acquisition unit 313 acquires the rotation angle from the angle sensor and calculates the rotation speed RS.
Therefore, the first release processing unit 314 can properly determine whether the rotation speed RS has reached or exceeded the speed threshold RTH.

4. Operation of the Control Device
Next, an example of the operation of the control device 3 will be described with reference to Fig. 4. Fig. 4 is a graph showing an example of the operation of the control device 3.
4 shows a graph showing the relationship between time T and rotation speed RS. The horizontal axis of the graph represents time T, and the vertical axis represents rotation speed RS.
Graph G1 shows the change in rotation speed RS over time. As shown in graph G1, rotation speed RS decreases as short circuit control unit 311 executes three-phase short circuit control. Then, rotation speed RS reaches speed threshold value RTH at time T1.
Furthermore, in order for the short-circuit control unit 311 to execute three-phase short-circuit control, all of the MOSFETs on the positive side of the motor driver 14 are turned off and all of the MOSFETs on the negative side of the motor driver 14 are turned on. That is, the short-circuit control unit 311 turns off all of the MOSFETs 14U1, 14V1, and 14W1 connected to the positive terminal 14P of the motor driver 14. The short-circuit control unit 311 also turns on all of the MOSFETs 14U2, 14V2, and 14W2 connected to the negative terminal 14M of the motor driver 14.

At time T1, the first release processing unit 314 starts the following control. That is, when the current value IU, IV, IW flowing through one coil (e.g., motor coil 15U) of the three coils (15U, 15V, 15W) of the three-phase motor 15 is less than or equal to a first threshold value TH1 that is greater than zero and greater than or equal to zero, the first release processing unit 314 turns off the negative-side MOSFET (e.g., MOSFET 14U2) corresponding to that coil (e.g., motor coil 15U).

The middle section of Figure 4 shows a graph showing the relationship between time T and current values IU, IV, and IW. The horizontal axis of the graph represents time T, and the vertical axis represents current values IU, IV, and IW. Graph G21 shows the change in current value IU over time, graph G22 shows the change in current value IV over time, and graph G23 shows the change in current value IW over time.

As shown in graph G21, the current value IU becomes zero at time T2. Therefore, the first release processing unit 314 determines that, for example, at time T2, the current value IU is equal to or less than the first threshold value TH1, which is greater than zero, and is equal to or greater than zero. The first release processing unit 314 then turns off the negative-side MOSFET 14U2 corresponding to the motor coil 15U. As a result, the current value IU is maintained at zero from time T2 onwards.

Since the current value IU is maintained at zero from time T2 onwards, as shown in the upper graph G1 in Figure 4, the change in rotation speed RS per unit time is reduced compared to when three-phase short-circuit control is being executed.

Furthermore, as shown in graphs G22 and G23, the current values IV and IW each become zero at time T3. Therefore, the second release processing unit 315 determines that, for example, at time T3, the current values IV and IW are each equal to or less than the second threshold value TH2. The second release processing unit 315 then turns off the negative-side MOSFET 14V2 corresponding to motor coil 15V and the negative-side MOSFET 14W2 corresponding to motor coil 15W. As a result, the current values IV and IW are maintained at zero from time T3 onwards.

The bottom part of Figure 4 shows a graph showing the relationship between time T and surge voltage VS. The horizontal axis of the graph represents time T, and the vertical axis represents surge voltage VS. The voltage VM shown by the dashed line represents the withstand voltage of the MOSFET. Graph G31 shows an example of surge voltage VS1 generated in motor coil 15U, and graph G32 shows an example of surge voltage VS2 generated in motor coil 15V and motor coil 15W.

As shown in graph G31, surge voltage VS1 generated in motor coil 15U begins to increase at time T2 and reaches a constant value at time T4. As shown in graph G32, surge voltage VS2 generated in motor coil 15V and motor coil 15W begins to increase at time T3 and reaches a constant value at time T5. In this embodiment, the maximum value of surge voltage VS1 approximately coincides with the maximum value of surge voltage VS2.

Furthermore, as shown in graphs G31 and G32, the maximum values of surge voltage VS1 and surge voltage VS2 are smaller than the withstand voltage VM of the MOSFET, thereby preventing damage to the MOSFET due to surge voltage VS1 and surge voltage VS2.

4 illustrates a case in which first release processing unit 314 turns off negative-side MOSFET 14U2 corresponding to motor coil 15U at time T2 when current value IU becomes zero, but the present invention is not limited to this. First release processing unit 314 may turn off negative-side MOSFET 14U2 corresponding to motor coil 15U when current value IU is equal to or less than first threshold value TH1 and equal to or greater than zero.
4 illustrates a case in which the second release processing unit 315 turns off the MOSFET 14V2 and the MOSFET 14W2 at time T3 when the current value IV and the current value IW become zero, but the present invention is not limited to this. The second release processing unit 315 may turn off the MOSFET 14V2 and the MOSFET 14W2 when the current value IV and the current value IW are equal to or less than the second threshold value TH2.

Also, in FIG. 4, a case is described in which the first release processing unit 314 turns off the negative-side MOSFET 14U2 corresponding to the motor coil 15U, and the second release processing unit 315 turns off the negative-side MOSFET 14V2 corresponding to the motor coil 15V and the negative-side MOSFET 14W2 corresponding to the motor coil 15W, but this is not limiting.
For example, the first release processing unit 314 may turn off the negative-side MOSFET 14V2 corresponding to the motor coil 15V, and the second release processing unit 315 may turn off the negative-side MOSFET 14U2 corresponding to the motor coil 15U and the negative-side MOSFET 14W2 corresponding to the motor coil 15W. Alternatively, for example, the first release processing unit 314 may turn off the negative-side MOSFET 14W2 corresponding to the motor coil 15W, and the second release processing unit 315 may turn off the negative-side MOSFET 14U2 corresponding to the motor coil 15U and the negative-side MOSFET 14V2 corresponding to the motor coil 15V.

[5. Processing of the control device]
Next, the processing of the control device 3 will be described with reference to Fig. 5. Fig. 5 is a flowchart showing an example of the processing of the control device 3.
First, in step S101, the short circuit control unit 311 determines whether the contactor 12 is off.
If the short-circuit control unit 311 determines that the contactor 12 is not off (step S101; NO), the process goes to a standby state. If the short-circuit control unit 311 determines that the contactor 12 is off (step S101; YES), the process proceeds to step S103.
Then, in step S103, the short circuit control unit 311 determines whether or not the motor driver 14 is executing three-phase short circuit control.
If the short circuit control unit 311 determines that the motor driver 14 is not executing three-phase short circuit control (step S103; NO), the process goes to a standby state. If the short circuit control unit 311 determines that the motor driver 14 is executing three-phase short circuit control (step S103; YES), the process proceeds to step S105.

Then, in step S<b>105 , the speed acquisition unit 313 acquires the rotation speed RS of the three-phase motor 15 from the speed detection circuit 33 .
Next, in step S107, the first release processing unit 314 determines whether the rotation speed RS acquired in step S105 is equal to or less than the speed threshold value RTH.
If the first release processing unit 314 determines that the rotation speed RS is not equal to or less than the speed threshold RTH (step S107; NO), the process returns to step S105. If the first release processing unit 314 determines that the rotation speed RS is equal to or less than the speed threshold RTH (step S107; YES), the process proceeds to step S109.
Then, in step S109, the current acquisition unit 312 acquires the current values IU, IV, and IW from the current sensor SC. The current value IU is the value of the current flowing through the motor coil 15U. The current value IV is the value of the current flowing through the motor coil 15V. The current value IW is the value of the current flowing through the motor coil 15W.
Next, in step S111, the first release processing unit 314 determines whether any one of the current values IU, IV, and IW is equal to or greater than zero and equal to or less than a first threshold value TH1.

If the first release processing unit 314 determines that any one of the current values IU, IV, and IW is equal to or greater than zero and equal to or less than the first threshold value TH1 (step S111; NO), the process returns to step S109. If the first release processing unit 314 determines that any one of the current values IU, IV, and IW is equal to or greater than zero and equal to or less than the first threshold value TH1 (step S111; YES), the process proceeds to step S113.
Then, in step S113, the first release processing unit 314 turns off the MOSFET on the negative side of one motor coil corresponding to one current value. For example, if the one current value is current value IU, the first release processing unit 314 turns off MOSFET 14U2.
Next, in step S115, the current obtaining unit 312 obtains the current values IU, IV, and IW from the current sensor SC.
Next, in step S117, the second release processing unit 315 determines whether the other two current values are equal to or less than the second threshold value TH2. For example, if the other current value is the current value IU, the other two current values are the current value IV and the current value IW.

If the second release processing unit 315 determines that the two current values are not equal to or less than the second threshold value TH2 (step S117; NO), the process returns to step S115. If the second release processing unit 315 determines that the two current values are equal to or less than the second threshold value TH2 (step S117; YES), the process proceeds to step S119.
Then, in step S119, the second release processing unit 315 turns off the MOSFETs on the negative sides of the two motor coils corresponding to the two current values. For example, if the two current values are current value IV and current value IW, the second release processing unit 315 turns off MOSFET 14V2 and MOSFET 14W2. The process then ends.

Steps S109 and S115 correspond to an example of a "current acquisition step." Step S105 corresponds to an example of a "speed acquisition step." Steps S111 and S113 correspond to an example of a "first release processing step." Steps S117 and S119 correspond to an example of a "second release processing step."

[6. Composition and Effects]
As described above, the vehicle drive control device 100 according to this embodiment is arranged between the battery 11 and the three-phase motor 15 that drives the vehicle, and includes a motor driver 14 configured with MOSFETs and controlling the three-phase motor 15, and a control device 3 that controls the motor driver 14. The control device 3 includes a current acquisition unit 312 that acquires current values IU, IV, and IW flowing through the motor coils 15U, 15V, and 15W of the three-phase motor 15, a speed acquisition unit 313 that acquires the rotation speed RS of the three-phase motor 15, and a speed acquisition unit 314 that acquires the rotation speed RS of the three-phase motor 15 when the rotation speed RS is equal to or less than the speed threshold RTH while the motor driver 14 is executing three-phase short-circuit control. In this case, the three-phase motor 15 includes a first release processing unit 314 that turns off the negative-side MOSFET corresponding to one of the three motor coils 15U, 15V, 15W of the three-phase motor 15 when the current value flowing through one of the three motor coils 15U, 15V, IW is equal to or less than a first threshold value TH1 that is greater than zero and is equal to or greater than zero, and a second release processing unit 315 that turns off the negative-side MOSFET corresponding to each of the two coils of the three motor coils 15U, 15V, 15W when the current value flowing through the other two coils is equal to or less than a second threshold value TH2.
According to this configuration, when the current value flowing through one coil (e.g., motor coil 15U) of the current values IU, IV, and IW flowing through the three motor coils 15U, 15V, and 15W of the three-phase motor 15 is equal to or less than a first threshold value TH1 that is greater than zero and is equal to or greater than zero, the negative-side MOSFET (e.g., MOSFET 14U2) corresponding to the one coil (e.g., motor coil 15U) is turned off. Therefore, by setting the first threshold value TH1 to an appropriate value, it is possible to suppress the surge voltage VS1 generated in the one coil (e.g., motor coil 15U).
Furthermore, when the value of the current (e.g., current values IV and IW) flowing through two of the three motor coils 15U, 15V, and 15W (e.g., motor coils 15V and 15W) other than one coil (e.g., motor coil 15U) is equal to or less than the second threshold value TH2, the negative-side MOSFETs (e.g., MOSFET 14V2 and MOSFET 14W2) corresponding to each of the two coils (e.g., motor coils 15V and 15W) are turned off. Therefore, by setting the second threshold value TH2 to an appropriate value, the surge voltage VS2 generated in the two coils (e.g., MOSFET 14V2 and MOSFET 14W2) can be suppressed.

In the vehicle drive control device 100, the second threshold value TH2 is set to a value greater than the first threshold value TH1.
According to this configuration, even if the current values (e.g., current values IV and IW) flowing through two coils (e.g., MOSFET 14V2 and MOSFET 14W2) do not change to correspond to each other, the negative-side MOSFETs (e.g., MOSFET 14V2 and MOSFET 14W2) corresponding to each of the two coils (e.g., motor coils 15V and 15W) can be turned off early.

Furthermore, in the vehicle drive control device 100, after the rotation speed RS reaches or falls below the speed threshold value RTH, the first release processing unit 314 turns off the negative-side MOSFET (e.g., MOSFET 14U2) corresponding to one coil (e.g., motor coil 15U) when the condition that the current value IU, IV, IW flowing through each motor coil 15U, 15V, 15W of the three-phase motor 15 is less than or equal to a first threshold value TH1 that is greater than zero and greater than or equal to zero is met for the first time.
This configuration allows the negative-side MOSFET (e.g., MOSFET 14U2) corresponding to one coil (e.g., motor coil 15U) to be turned off early, thereby shortening the period during which three-phase short-circuit control is performed. As a result, the three-phase motor 15 can be prevented from becoming too hot.

In the vehicle drive control device 100, the control device 3 also includes a speed detection circuit 33 that calculates the rotation speed RS from the current values IU, IV, IW flowing through the motor coils 15U, 15V, 15W of the three-phase motor 15.
With this configuration, the time required to calculate the rotation speed RS can be reduced because the speed detection circuit 33 calculates the rotation speed RS from the current values IU, IV, and IW flowing through each of the motor coils 15U, 15V, and 15W of the three-phase motor 15. Therefore, the first release processing unit 314 can turn off the negative-side MOSFET (e.g., MOSFET 14U2) corresponding to one coil (e.g., motor coil 15U) at the appropriate timing.

The vehicle drive control device 100 also includes a contactor 12 disposed between the battery 11 and the motor driver 14. When the contactor 12 is off, the first release processing unit 314 turns off the negative-side MOSFET (e.g., MOSFET 14U2) corresponding to one coil (e.g., motor coil 15U), and the second release processing unit 315 turns off the negative-side MOSFET (e.g., MOSFET 14V2 and MOSFET 14W2) corresponding to each of the two coils (e.g., motor coils 15V and 15W).
According to this configuration, when the contactor 12 is off, it is possible to suppress the surge voltages VS1 and VS2 that are generated when the negative-side MOSFETs (MOSFET 14U2, MOSFET 14V2, and MOSFET 14W2) are turned off.

The control method for the vehicle drive control device 100 according to this embodiment is a control method for the vehicle drive control device 100, which includes a motor driver 14 configured with MOSFETs and arranged between a battery 11 and a three-phase motor 15 that drives the vehicle, and which controls the three-phase motor 15, and a control device 3 that controls the motor driver 14, in which the control device 3 includes a current acquisition step of acquiring current values IU, IV, IW flowing through each of motor coils 15U, 15V, 15W of the three-phase motor 15, a speed acquisition step of acquiring a rotation speed RS of the three-phase motor 15, and a step of acquiring a current value IU, IV, IW flowing through one coil (e.g., 15U, 15V, 15W) of the three-phase motor 15 when the rotation speed RS is equal to or less than a speed threshold RTH while the motor driver 14 is performing three-phase short-circuit control. For example, a first release process step is executed in which a negative-side MOSFET (e.g., MOSFET 14U2) corresponding to one coil (e.g., motor coil 15U) is turned off when the value of the current flowing through the coil is equal to or less than a first threshold value TH1 greater than zero and equal to or greater than zero; and a second release process step is executed in which a negative-side MOSFET (e.g., MOSFET 14V2 and MOSFET 14W2) corresponding to each of two coils (e.g., motor coils 15V and 15W) other than one coil (e.g., motor coil 15U) out of the three motor coils 15U, 15V, and 15W is turned off when the value of the current (e.g., current values IV and IW) flowing through two coils (e.g., motor coils 15V and 15W) other than one coil (e.g., motor coil 15U) is equal to or less than a second threshold value TH2.
According to this configuration, when the current value flowing through one coil (e.g., motor coil 15U) of the current values IU, IV, and IW flowing through the three motor coils 15U, 15V, and 15W of the three-phase motor 15 is equal to or less than a first threshold value TH1 that is greater than zero and is equal to or greater than zero, the negative-side MOSFET (e.g., MOSFET 14U2) corresponding to the one coil (e.g., motor coil 15U) is turned off. Therefore, by setting the first threshold value TH1 to an appropriate value, it is possible to suppress the surge voltage VS1 generated in the one coil (e.g., motor coil 15U).
Furthermore, when the value of the current (e.g., current values IV and IW) flowing through two of the three motor coils 15U, 15V, and 15W (e.g., motor coils 15V and 15W) other than one coil (e.g., motor coil 15U) is equal to or less than the second threshold value TH2, the negative-side MOSFETs (e.g., MOSFET 14V2 and MOSFET 14W2) corresponding to each of the two coils (e.g., motor coils 15V and 15W) are turned off. Therefore, by setting the second threshold value TH2 to an appropriate value, the surge voltage VS2 generated in the two coils (e.g., MOSFET 14V2 and MOSFET 14W2) can be suppressed.

7. Other Embodiments
The present invention is not limited to the configurations of the above-described embodiments, and can be implemented in various forms without departing from the spirit of the invention.

For example, in the above embodiment, the "switching element" is described as a MOSFET, but this is not limited to this. The "switching element" may also be, for example, a power transistor or an IGBT (Insulated Gate Bipolar Transistor).

In addition, in the above embodiment, the control device 3 is described as including a speed detection circuit 33, but this is not limited to this. For example, the control device 3 may include an angle sensor that detects the rotation angle of the three-phase motor 15, and the speed acquisition unit 313 may acquire the rotation angle from the angle sensor and calculate the rotation speed RS.

At least some of the functional blocks shown in FIG. 2 may be realized by hardware, or may be realized by a combination of hardware and software, and are not limited to a configuration in which independent hardware resources are arranged as shown in the figure.
The control program 321 executed by the processor 31 of the control device 3 of the vehicle drive control device 100 is stored in the memory 32, but the control program 321 may also be stored in an external HDD or the like.

The processing units in the flowchart shown in Figure 5 are divided according to the main processing content to facilitate understanding of the processing of the control device 3 of the vehicle drive control device 100. The method of division and names of the processing units shown in the flowchart in Figure 5 do not limit the embodiment. The processing of the control device 3 can be divided into more processing units depending on the processing content, or one processing unit can be divided so that it includes more processes. The processing order of the above flowchart is not limited to the example shown.

The control method of the control device 3 can be realized by having the processor 31 of the control device 3 execute a control program 321 corresponding to the control method of the control device 3. The control program 321 can be recorded on a computer-readable recording medium. The recording medium can be a magnetic or optical recording medium or a semiconductor memory device.
Specific examples include portable or fixed recording media such as flexible disks, CD-ROMs (Compact Disk Read Only Memory), DVDs (Digital Versatile Discs), Blu-ray (registered trademark) Discs, magneto-optical disks, flash memories, and card-type recording media.
The recording medium may be a non-volatile storage device such as a RAM, ROM, or HDD that is an internal storage device provided in the control device 3. The control program 321 corresponding to the control method of the control device 3 is stored in a server device or the like, and the control method of the control device 3 can be realized by downloading the control program 321 from the server device to the control device 3.

8. Configurations supported by the above embodiments
The above embodiment supports the following configurations.

(Configuration 1) A vehicle drive control device comprising: a motor driver arranged between a power source and a three-phase motor that drives a vehicle, the motor driver being composed of switching elements and controlling the three-phase motor; and a control device that controls the motor driver, wherein the control device comprises: a current acquisition unit that acquires current values flowing in each coil of the three-phase motor; a speed acquisition unit that acquires the rotational speed of the three-phase motor; a first release processing unit that, when the motor driver is performing three-phase short circuit control and the rotational speed is below a predetermined threshold, turns off a negative-side switching element corresponding to one of the current values flowing in the one coil when the current value flowing in the one coil is below a first threshold greater than zero and above zero; and a second release processing unit that turns off the negative-side switching elements corresponding to each of the two coils when the current values flowing in two of the three coils excluding the one coil are below a second threshold.
According to the vehicle drive control device of configuration 1, by setting the first threshold value to an appropriate value, it is possible to suppress the surge voltage generated in the one coil. Also, by setting the second threshold value to an appropriate value, it is possible to suppress the surge voltage generated in the two coils. Therefore, it is possible to suppress the surge voltage when three-phase short circuit control is terminated.

(Configuration 2) The vehicle drive control device according to configuration 1, wherein the second threshold value is set to a value greater than the first threshold value.
According to the vehicle drive control device of configuration 2, the negative side switching elements corresponding to the two coils can be turned off early.

(Configuration 3) The vehicle drive control device described in Configuration 1 or Configuration 2, wherein the first release processing unit turns off the negative side switching element corresponding to one coil when, after the rotational speed reaches a predetermined threshold or less, the condition that the current value flowing through one coil of the three-phase motor is less than or equal to a first threshold greater than zero and greater than or equal to zero is met for the first time.
According to the vehicle drive control device of configuration 3, the negative side switching element corresponding to the one coil can be turned off early.

(Configuration 4) The vehicle drive control device according to any one of configurations 1 to 3, wherein the control device includes a circuit that calculates the rotation speed from a current value flowing through each coil of the three-phase motor.
According to the vehicle drive control device of configuration 4, the time required to calculate the rotation speed can be reduced, and therefore the negative side switching element corresponding to one of the coils can be turned off at an appropriate timing.

(Configuration 5) A vehicle drive control device according to any one of configurations 1 to 4, further comprising a switch arranged between the power supply and the motor driver, wherein when the switch is off, the first release processing unit turns off the negative-side switching element corresponding to one of the coils, and the second release processing unit turns off the negative-side switching elements corresponding to each of the two coils.
According to the vehicle drive control device of configuration 5, when the switch is off, the surge voltage VS2 that occurs when the three-phase short circuit control is terminated can be suppressed.

(Configuration 6) A control method for a vehicle drive control device comprising: a motor driver arranged between a power source and a three-phase motor that drives a vehicle, the motor driver being composed of switching elements and controlling the three-phase motor; and a control device that controls the motor driver, wherein the control device executes the following steps: a current acquisition step for acquiring current values flowing in each coil of the three-phase motor; a speed acquisition step for acquiring the rotational speed of the three-phase motor; a first release processing step for turning off a negative-side switching element corresponding to one of the current values flowing in one coil of the three-phase motor when the current value flowing in the one coil is less than or equal to a first threshold greater than zero and greater than or equal to zero when the rotational speed is less than or equal to a predetermined threshold while the motor driver is performing three-phase short circuit control; and a second release processing step for turning off the negative-side switching elements corresponding to each of the two coils when the current values flowing in two of the three coils excluding the one coil are less than or equal to a second threshold.
According to the control method for a vehicle drive control device of configuration 6, the surge voltage generated in the one coil can be suppressed by setting the first threshold to an appropriate value. Also, the surge voltage generated in the two coils can be suppressed by setting the second threshold to an appropriate value. Therefore, the surge voltage generated when three-phase short circuit control is terminated can be suppressed.

100 Vehicle drive control device 1 Motor drive circuit 11 Battery (power source)
12 Contactor (switch)
13 Capacitor 14 Motor driver 14P Positive terminal 14M Negative terminal 14U1, 14U2, 14V1, 14V2, 14W1, 14W2 MOSFET (switching element)
15 three-phase motor,
15U, 15V, 15W Motor coil 2 Driver drive circuit 3 Control device 31 Processor 311 Short circuit control unit 312 Current acquisition unit 313 Speed acquisition unit 314 First release processing unit 315 Second release processing unit 32 Memory 321 Control program 33 Speed detection circuit (part of the speed acquisition unit)
331 Zero time detection circuit 332 Period calculation circuit 333 Rotation speed calculation circuit IU, IV, IW Current value RS Rotation speed RTH Speed threshold (speed threshold)
SC Current sensor T Time TH1 First threshold TH2 Second threshold TM Period TZ Zero time VM Withstand voltage VS, VS1, VS2 Surge voltage ΔTZ Difference

Claims (5)

a motor driver that is arranged between a power source and a three-phase motor that drives a vehicle, the motor driver being configured with switching elements and controlling the three-phase motor;
a control device that controls the motor driver,
The control device
a current acquisition unit that acquires a current value flowing through each coil of the three-phase motor;
a speed acquisition unit that acquires a rotational speed of the three-phase motor;
a first release processing unit that turns off a negative-side switching element corresponding to one coil when a current value flowing through one of three coils of the three-phase motor is equal to or less than a first threshold value greater than zero and equal to or greater than zero when the rotation speed is equal to or less than a predetermined threshold value while the motor driver is executing three-phase short circuit control;
a second release processing unit that turns off the negative-side switching elements corresponding to the two coils when a value of a current flowing through two coils other than the one coil among the three coils is equal to or less than a second threshold value;
Equipped with
The second threshold value is set to a value equal to or less than a predetermined value and greater than the first threshold value . the first release processing unit turns off the negative-side switching element corresponding to one coil when, after the rotation speed reaches a predetermined threshold or less, a condition is satisfied for the first time that a current value flowing through one coil among current values flowing through the coils of the three-phase motor is equal to or less than a first threshold value greater than zero and equal to or greater than zero;
The vehicle drive control device according to claim 1. The control device includes a circuit for calculating the rotation speed from a current value flowing through each coil of the three-phase motor.
The vehicle drive control device according to claim 1. a switch disposed between the power supply and the motor driver;
When the switch is off, the first release processing unit turns off the negative-side switching element corresponding to the one coil, and the second release processing unit turns off the negative-side switching elements corresponding to each of the two coils.
The vehicle drive control device according to any one of claims 1 to 3 . a motor driver that is arranged between a power source and a three-phase motor that drives a vehicle, the motor driver being configured with switching elements and controlling the three-phase motor;
a control device that controls the motor driver,
The control device
a current acquisition step of acquiring a current value flowing through each coil of the three-phase motor;
a speed acquisition step of acquiring a rotational speed of the three-phase motor;
a first release processing step of turning off a negative-side switching element corresponding to one coil when a current value flowing through one of three coils of the three-phase motor is equal to or less than a first threshold value greater than zero and equal to or greater than zero while the rotation speed is equal to or less than a predetermined threshold value while the motor driver is executing three-phase short circuit control;
a second release process step of turning off the negative-side switching elements corresponding to the two coils, when the current values flowing through the two coils other than the one coil among the three coils are equal to or less than a second threshold value;
Run
The second threshold value is set to a value equal to or less than a predetermined value and greater than the first threshold value .