JP7207044B2 - motor drive - Google Patents

Description

The present invention relates to a motor drive device.

2. Description of the Related Art In an electric system that includes an inverter and a rotating electric machine that are used in an electric vehicle such as a hybrid vehicle, there are cases where some kind of malfunction occurs in components that make up the system. In order to protect the system from continuous damage when such a problem occurs, there is a known technique for switching to a short-circuit mode in which the semiconductor switching elements that make up the inverter are operated to short-circuit the windings of the rotating electric machine. ing.

Here, a method for short-circuiting the windings of the rotating electrical machine by controlling the switching elements forming the inverter will be described. For example, FIG. 1 shows an electrical system including a DC power supply 100, a three-phase inverter 200 having a smoothing capacitor 201 and a DC/AC converter 202, and a rotating electric machine 300. FIG. To short-circuit the windings of rotating electric machine 300, the three switching elements forming the lower arm of three-phase inverter 200 are turned on, and the three switching elements forming the upper arm are turned off. Also, the ON/OFF of the switching element of each arm may be reversed.

Malfunctions of components that make up the system include malfunctions of the drive circuit and control circuit that drive the switching elements of the three-phase inverter 200, and the power supply circuit that supplies power to these circuits (none of which is shown).

In the event of system failure, it is required to short-circuit the windings of the rotating electrical machine to suppress the generation of induced voltage (regenerative voltage) that exceeds the withstand voltage of the inverter's main circuit, thereby protecting the main circuit. . In particular, in the event of an emergency such as a collision of an electric vehicle, the main battery should be disconnected to ensure the safety of the occupants, and the output voltage of the inverter (the voltage of the smoothing capacitor between the positive and negative DC bus lines) should drop below the specified value within a predetermined time. required to be reduced to

However, if the rotating electrical machine remains in the short circuit mode with the main battery disconnected, no energy will be supplied to the DC bus of the main circuit. If this state continues and the stored energy in the smoothing capacitor connected between the positive and negative DC bus lines is used up, the power supply circuit that operates the winding short-circuit control circuit for short-circuiting the windings of the rotating electrical machine stops. As a result, the short-circuit mode is canceled and the DC bus voltage rises even though the rotating electrical machine is in the power generating state. During this time, the DC bus voltage may exceed the specified value.

Therefore, the DC bus voltage of the main circuit is detected, and when this voltage drops below a preset threshold (short-circuit OFF threshold), the winding short circuit of the rotating electrical machine is released, and the DC bus voltage rises again to reach the threshold (short-circuit ON). There is a technique for short-circuiting the windings again when the current exceeds the threshold value (see, for example, Patent Document 1).

Japanese Patent No. 5433608

However, if the fail-safe operation, which repeatedly shorts and unshorts the windings, is performed separately for the motor that rotates the left wheel and the motor that rotates the right wheel, a torque imbalance occurs between the left and right wheels. However, in some cases, the stability of the behavior of the vehicle deteriorated.

Accordingly, the present disclosure provides a motor drive device capable of ensuring stability of vehicle behavior when performing a fail-safe operation in which winding short-circuiting and winding short-circuit cancellation are repeated.

This disclosure is
a first inverter that drives a first motor that rotates the left wheel of the vehicle;
a first capacitor that is discharged when the windings of the first motor are short-circuited by the first inverter and charged when the winding short-circuiting of the first motor is removed by the first inverter; ,
a second inverter that drives a second motor that rotates the right wheel of the vehicle;
a second capacitor that is discharged when the windings of the second motor are short-circuited by the second inverter and charged when the winding short-circuits of the second motor are removed by the second inverter; ,
When the voltage of the DC bus commonly connected to the first capacitor and the second capacitor reaches a first threshold, the first motor and the second capacitor are connected by the first inverter and the second inverter. 2 motors at the same time, and when the voltage of the DC bus reaches a second threshold lower than the first threshold, the first inverter and the second inverter operate the first inverter. and a control device that repeats releasing short-circuited windings of both the motor and the second motor at the same time.

This disclosure also provides
a first inverter that drives a first motor that rotates the left wheel of the vehicle;
a first capacitor that is discharged when the windings of the first motor are short-circuited by the first inverter and charged when the winding short-circuiting of the first motor is removed by the first inverter; ,
a second inverter that drives a second motor that rotates the right wheel of the vehicle;
a second capacitor that is discharged when the windings of the second motor are short-circuited by the second inverter and charged when the winding short-circuits of the second motor are removed by the second inverter; ,
If the voltage of either the first capacitor or the second capacitor reaches the first threshold first, the first motor and the second motor are controlled by the first inverter and the second inverter. If the voltage of either the first capacitor or the second capacitor reaches a second threshold lower than the first threshold first, the first inverter and a control device that repeats releasing short-circuited windings of both the first motor and the second motor by the second inverter at the same time.

This disclosure also provides
a first inverter that drives a first motor that rotates one of left and right wheels of the vehicle;
a first capacitor that is discharged when the windings of the first motor are short-circuited by the first inverter and charged when the winding short-circuiting of the first motor is removed by the first inverter; ,
a second inverter that drives a second motor that rotates the other of the left and right wheels of the vehicle;
a second capacitor that is discharged when the windings of the second motor are short-circuited by the second inverter and charged when the winding short-circuits of the second motor are removed by the second inverter; ,
When the voltage of the first capacitor reaches a first threshold, the windings of both the first motor and the second motor are simultaneously short-circuited by the first inverter and the second inverter, and the When the voltage on the first capacitor reaches a second threshold that is lower than the first threshold, the winding of both the first motor and the second motor is controlled by the first inverter and the second inverter. A control device that repeats releasing the line short circuit at the same time,
When the voltage of the second capacitor is higher than the first threshold, the control device alternately turns on and off the upper and lower arms of the second inverter to short-circuit the windings of the second motor. A motor drive is provided.

According to the technology of the present disclosure, it is possible to provide a motor drive device capable of ensuring stability of vehicle behavior when performing a fail-safe operation in which winding short-circuiting and winding short-circuiting are repeated.

It is a figure which shows the structural example of an electric system provided with an inverter and a rotary electric machine. It is a figure which shows the structural example of the motor drive device in a 1st comparative form. It is a figure which shows the structural example of the motor drive device in 1st Embodiment. 4 is a flowchart showing an operation example of the motor drive device in the first embodiment; 4 is a diagram illustrating operation waveforms of the motor drive device in the first embodiment; FIG. It is a figure which shows the structural example of the motor drive device in a 2nd comparative form. It is a figure which illustrates the operation|movement waveform of the motor drive device in a 2nd comparative form. It is a figure which illustrates the operation|movement waveform of the motor drive device in a 2nd comparative form. It is a figure which shows the structural example of the motor drive device in 2nd Embodiment. FIG. 7 is a diagram illustrating operation waveforms of the motor drive device according to the second embodiment; It is a figure which shows the 1st detailed example of a structure of the motor drive device in 2nd Embodiment. 12 is a diagram showing a detailed configuration example of the charging control circuit of FIG. 11; FIG. FIG. 10 is a diagram showing a second detailed configuration example of the motor drive device according to the second embodiment; 14 is a diagram showing a detailed configuration example of the charging control circuit of FIG. 13; FIG. FIG. 7 is a diagram illustrating operation waveforms of the motor drive device according to the second embodiment; 12 is a diagram showing a detailed configuration example of the charging control circuit of FIG. 11; FIG. 17 is a truth table for the logic circuit of FIG. 16;

<First comparison mode>
First, before describing the motor driving device according to the first embodiment of the present disclosure, a motor driving device according to a first comparative embodiment will be described for comparison with the motor driving device according to the first embodiment.

FIG. 2 is a diagram showing a configuration example of a motor drive device in a first comparative embodiment. A motor drive device 100a shown in FIG. 2 is a comparative example for comparison with a motor drive device 101 in a first embodiment described later.

The motor driving device 100a includes four control devices 7a-7d (ECUs 7a-7d) and four inverters 1-4 (INV1-4). The ECU 7a controls the inverter 1 that drives the motor M1 that rotates the left rear wheel RL of the vehicle, and the ECU 7b controls the inverter 2 that drives the motor M2 that rotates the right rear wheel RR of the vehicle. The ECU 7c controls the inverter 3 that drives the motor M3 that rotates the front left wheel FL of the vehicle, and the ECU 7d controls the inverter 4 that drives the motor M4 that rotates the front right wheel FR of the vehicle. The ECUs 7a to 7d operate using a regular control power source (eg, a 12-volt low-voltage battery), not shown, having a voltage lower than that of the high-voltage battery 10 as a power source.

Inverters 1 and 2 are connected to a common DC bus 5a connected to a high voltage battery 10 via a contactor 6a, and inverters 3 and 4 are connected to a common DC bus 5b connected to the high voltage battery 10 via a contactor 6b. It is connected to the. Capacitors 9a and 9b are connected to the DC bus 5a, and capacitors 9c and 9d are connected to the DC bus 5b. Inverter 1 converts DC power supplied from high-voltage battery 10 via DC bus 5a into AC power in accordance with a drive signal generated by ECU 7a to drive motor M1. Inverters 2-4, like inverter 1, drive motors M2-M4, respectively, according to drive signals generated by corresponding ECUs 7b-7d. Inverters 1 to 4 each have the same configuration as DC/AC converter 202 (see FIG. 1).

Next, the fail-safe operation when a predetermined abnormality occurs (for example, when the normal control power supply is lost) will be described using the ECU 7a as an example.

When the regular control power supply is lost, the ECU 7a drives the inverter 1 in a fail-safe operation using power generated by an emergency power supply operating with the capacitor 9a as the power supply. The ECU 7a has a function of short-circuiting the windings of the motor M1 by turning on the upper arm or the lower arm of all the phases of the inverter 1 when detecting the loss of the regular control power supply. By short-circuiting the windings in this manner, the regenerated power of the motor M1 flowing into the inverter 1 can be suppressed, and the circuit components such as the capacitor 9a can be protected from overvoltage.

On the other hand, when a predetermined abnormality (for example, loss of the normal control power supply) occurs, the vehicle controller 8 higher than the ECUs 7a-7d may turn off the contactors 6a, 6b for fail-safe. In this case, if the ECU 7a continues the winding short-circuit while one arm (for example, the lower arm) of all the phases of the inverter 1 is turned on, regeneration is performed from the motor M1 through the drive circuit of each phase in the inverter 1. run out of power. If this state continues and the energy stored in the capacitors 9a and 9b is exhausted due to discharge, the emergency power supply that supplies electric power for operating the drive circuits of each phase in the ECU 7a and the inverter 1 stops, and the windings It becomes impossible to continue the short circuit. In order to prevent this, the ECU 7a short-circuits the windings of the motor M1 when the voltage of the capacitor 9a reaches a short-circuit off threshold set to a voltage value slightly higher than the minimum operating voltage (lower operating voltage) of the emergency power supply. To release. As a result, the regeneration (charging) from the motor M1 to the capacitor 9a is resumed, so that the operating power supply of the emergency power supply is ensured. Therefore, the emergency power supply can generate electric power for operating the ECU 7a and each phase drive circuit in the inverter 1 by using the regenerated electric power charged in the capacitor 9a. Since the voltage of the capacitor 9a rises again due to the regenerated power from the motor M1, the ECU 7a short-circuits the windings of the motor M1 again when the voltage of the capacitor 9a reaches the short-circuit ON threshold set higher than the short-circuit OFF threshold. Let

In this way, the ECU 7a performs a short-circuit operation of turning on one arm to short-circuit the windings of the motor M1 when the voltage of the capacitor 9a reaches the short-circuit ON threshold, and the short-circuit operation when the voltage of the capacitor 9a reaches the short-circuit OFF threshold. The release operation for releasing the operation is repeated. When this repetitive control is performed with the power supplied from the high-voltage battery 10 to the DC bus 5a interrupted by the contactor 6a, the voltage of the capacitor 9a falls within the voltage range between the short-circuit ON threshold and the short-circuit OFF threshold. It is maintained in a state of moving up and down as if straddling. Therefore, interruption of the emergency power supply can be prevented.

Similarly to the fail-safe operation by the ECU 7a, each of the ECUs 7b to 7d repeats the fail-safe operation of short-circuiting and canceling the short-circuiting of the winding when a predetermined abnormality occurs (for example, when the normal control power supply is lost). can be executed.

However, in the case of a vehicle in which the left and right wheels are driven by independent left and right motor drives, the following problems 1-1 and 1-2 occur if the left and right fail-safe operations that repeatedly short-circuit and cancel the short-circuited windings are performed separately. It is possible that

(Problem 1-1) If the timing of winding short-circuiting differs between the left and right motors, or the timing of winding short-circuit cancellation differs between the left and right motors, the difference between the torque generated in the left wheel and the torque generated in the right wheel imbalance occurs. As a result, an unintended yaw moment Ya may be generated in the vehicle, and the stability of the behavior of the vehicle may deteriorate.

(Problem 1-2) In particular, when the yaw moment Ya is generated due to the imbalance between the torque TL1 generated in the left rear wheel RL and the torque TL2 generated in the right rear wheel RR, the left front wheel FL and the right front wheel FR It is conceivable that the stability of the behavior of the vehicle may be further degraded compared to the case where an imbalance occurs between them.

Therefore, in order to solve these problems, the motor drive device in the first embodiment has a configuration that can ensure the stability of the behavior of the vehicle when performing a fail-safe operation that repeats winding short-circuiting and winding short-circuiting cancellation. have. The motor drive device according to the first embodiment will be described below.

<First embodiment>
FIG. 3 is a diagram showing a configuration example of the motor drive device according to the first embodiment. A motor drive device 101 shown in FIG. Descriptions of configurations and effects similar to those of the comparative embodiment described above are omitted or simplified by citing the above descriptions.

The ECU 16 controls the inverter 11 that drives the motor M1 that rotates the left rear wheel RL of the vehicle, and the ECU 17 controls the inverter 12 that drives the motor M2 that rotates the right rear wheel RR of the vehicle. The ECU 18 controls the inverter 13 that drives the motor M3 that rotates the front left wheel FL of the vehicle, and the ECU 19 controls the inverter 14 that drives the motor M4 that rotates the front right wheel FR of the vehicle.

The ECUs 16 to 19 operate using a normal control power source (eg, a 12-volt low-voltage battery), not shown, having a voltage lower than that of the high-voltage battery 10 as a power source. The ECUs 16-19 are installed inside or outside the housings of the corresponding inverters 11-14.

Inverters 11 to 14 are connected to a common DC bus 15 connected to high voltage battery 10 via contactor 6 . Capacitors 21 to 24 are connected to the DC bus 15 . Capacitors 21-24 are installed inside or outside the housings of inverters 11-14, respectively. Inverter 11 converts DC power supplied from high-voltage battery 10 via DC bus 15 into AC power according to a drive signal generated by ECU 16 to drive motor M1. Inverters 12-14, like inverter 11, drive motors M2-M4, respectively, according to drive signals generated by ECUs 17-19, respectively. Inverters 11 to 14 each have the same configuration as DC/AC converter 202 (see FIG. 1).

In FIG. 3, the charging control circuit 20 is a control device that operates using a regular control power supply as a power supply, like the ECUs 16-19. Note that the charging control circuit 20 may be a control device included in any one of the ECUs 16-19.

Charging control circuit 20 detects voltage Vdc of DC bus 15 commonly connected to capacitors 21-24. Since the capacitors 21 to 24 are connected in parallel to the DC bus 15, the voltage Vdc of the DC bus 15 is equal to the voltage of each of the capacitors 21 to 24, ignoring errors such as voltage drop due to wiring resistance. .

The charge control circuit 20 controls the windings supplied to the ECUs 16-19 so that the windings of the motors M1-M4 are simultaneously short-circuited by the inverters 11-14 when the voltage Vdc of the DC bus 15 rises and reaches the short-circuit ON threshold. The line short-circuit signal Ss is turned on (active). As a result, the ECUs 16-19 simultaneously short-circuit the windings of the motors M1-M4 by the inverters 11-14 by detecting the active winding short-circuit signal Ss. On the other hand, when the voltage Vdc of the DC bus 15 drops and reaches the short-circuit OFF threshold, the charge control circuit 20 supplies voltage to the ECUs 16-19 so that the short-circuits of the windings of the motors M1-M4 are simultaneously released by the inverters 11-14. turns off (inactive) the winding short-circuit signal Ss. As a result, the ECUs 16-19 detect the inactive winding short-circuit signal Ss, thereby releasing the winding short-circuits of the motors M1-M4 by the inverters 11-14 at the same time. The short-circuit on threshold is an example of a first threshold, and the short-circuit off threshold is an example of a second threshold that is lower than the first threshold.

Next, the fail-safe operation performed by the motor driving device 101 shown in FIG. 3 when the regular control power supply is lost will be described with reference to FIGS.

FIG. 4 is a flow chart showing an operation example of the motor drive device according to the first embodiment, and shows an example of a control method for realizing fail-safe operation when the normal control power supply is lost. FIG. 5 is a diagram exemplifying operation waveforms of the motor drive device in the first embodiment, and shows fail-safe operation by the control method shown in FIG. The horizontal axis represents time t [sec].

In step S11 of FIG. 4, when the normal control power supply is lost, the ECU 16 operates with electric power generated by the emergency power supply 1a operating with the capacitor 21 as the power supply, and the ECU 17 operates with the emergency power supply operating with the capacitor 22 as the power supply. It operates on the power generated by the power supply 1b. Further, when the normal control power supply is lost, the ECU 17 operates with electric power generated by the emergency power supply 1c operating with the capacitor 23 as the power supply, and the ECU 18 operates with the emergency power supply 1d operating with the capacitor 24 as the power supply. Works on electricity. The charging control circuit 20 also uses power generated by an emergency power supply that operates with capacitors (may be capacitors 21 to 24 or capacitors not shown) connected to the DC bus 15 as a power supply when the normal control power supply is lost. Operate. Further, when the normal control power supply is lost, the vehicle controller higher than the ECUs 16 to 19 and the charging control circuit 20 turns off the contactor 6 for failsafe. When the contactor 6 is turned off, the conduction between the high voltage battery 10 and the DC bus 15 is interrupted.

At step S13 in FIG. 4, the charge control circuit 20 determines whether or not the voltage Vdc of the DC bus 15 is equal to or higher than the short-circuit ON threshold Vth(ON). If the voltage Vdc is equal to or higher than the short-circuit ON threshold value Vth(ON), the charge control circuit 20 executes the process of step S15, and if the voltage Vdc is less than the short-circuit ON threshold value Vth(ON), the charge control circuit 20 does not process steps S15 to S19. , the voltage determination in step S13 is performed again.

In step S15, charging control circuit 20 turns on one arm (upper arm in the case of FIG. 5) of all phases of inverters 11-14 to avoid overvoltage in capacitors 21-24. The signal Ss is turned on (active). When the ECUs 16-19 detect the active winding short-circuit signal Ss, the ECUs 16-19 simultaneously switch the upper arms of all the phases of the inverters 11-14 from off to on, thereby short-circuiting the windings of the motors M1-M4 at the same time. By short-circuiting the windings of the motors M1-M4, regenerative energy from the motors M1-M4 is cut off. On the other hand, the energy stored in capacitors 21-24 is consumed in the operation for maintaining the upper arms of all the phases of inverters 11-14 in the ON state, so capacitors 21-24 are discharged. Therefore, voltage Vdc of DC bus 15 connected to capacitors 21-24 gradually decreases as shown in FIG.

Next, in step S17 of FIG. 4, the charge control circuit 20 determines whether or not the voltage Vdc of the DC bus 15 is equal to or lower than the short-circuit OFF threshold Vth (OFF). The charge control circuit 20 executes the process of step S19 when the voltage Vdc is equal to or lower than the short-circuit OFF threshold Vth (OFF), and does not process step S19 when the voltage Vdc is higher than the short-circuit OFF threshold Vth (OFF). , the voltage determination in step S13 is performed again.

In step S19, charging control circuit 20 turns off one arm (upper arm in the case of FIG. 5) of all phases of inverters 11-14 in order to avoid stoppage of emergency power supplies 1a-1d. The line short-circuit signal Ss is turned off (inactive). When the ECUs 16-19 detect the inactive winding short-circuit signal Ss, the ECUs 16-19 simultaneously switch the upper arms of all the phases of the inverters 11-14 from ON to OFF, thereby releasing the winding short-circuits of the motors M1-M4 at the same time. When the shorted windings of the motors M1-M4 are released, the capacitors 21-24 are charged by regenerated energy from the motors M1-M4. Therefore, voltage Vdc of DC bus 15 connected to capacitors 21-24 gradually increases as shown in FIG.

The charging control circuit 20 repeats a series of processes of steps S13 to S19.

In this manner, the charge control circuit 20 performs a short-circuit operation to turn on one arm to short-circuit the windings of the motors M1 to M4 when the voltage Vdc reaches the short-circuit ON threshold, and a short-circuit operation to short-circuit the windings of the motors M1 to M4 when the voltage Vdc reaches the short-circuit OFF threshold. The canceling operation for canceling the short-circuiting operation is repeated. When this repetitive control is performed in a state in which the power supplied from the high-voltage battery 10 to the DC bus 15 is interrupted by the contactor 6, the voltage Vdc changes between the short-circuit ON threshold and the short-circuit OFF threshold, as shown in FIG. It is maintained in a state of swinging up and down across the voltage range in between. Therefore, interruption of the emergency power sources 1a to 1d can be prevented.

In addition, charging control circuit 20 simultaneously short-circuits both windings of motors M3 and M4 when voltage Vdc reaches a short-circuit ON threshold, and short-circuits both windings of motors M3 and M4 when voltage Vdc reaches a short-circuit OFF threshold. Simultaneous release of line shorts is repeated. As a result, the timing of winding short circuit between the motors M3 and M4 can be matched, and the timing of releasing the winding short circuit between the motors M3 and M4 can be matched. Therefore, the torque imbalance between the left and right front wheels due to the turning on and off of the winding short-circuit is suppressed, so that the stability of the behavior of the vehicle can be ensured when performing the fail-safe operation that repeats the winding short-circuit and the winding short-circuit release. In this case, the motor M3 is an example of a first motor that rotates the left wheel, and the inverter 13 is an example of a first inverter that drives the first motor. The motor M4 is an example of a second motor that rotates the right wheel, and the inverter 14 is an example of a second inverter that drives the second motor. The capacitor 23 is an example of a first capacitor, and the capacitor 24 is an example of a second capacitor. The charging control circuit 20 is an example of a control device that repeats simultaneous short-circuiting of windings and simultaneous release of short-circuiting of windings.

Similarly, charging control circuit 20 simultaneously shorts the windings of both motors M1 and M2 when voltage Vdc reaches the short-circuit on threshold, and both windings of motors M1 and M2 when voltage Vdc reaches the short-circuit off threshold. Simultaneous release of shorted windings is repeated. As a result, the timing of winding short circuit between the motors M1 and M2 can be matched, and the timing of releasing the winding short circuit between the motors M1 and M2 can be matched. Therefore, the torque imbalance between the left and right rear wheels caused by turning on and off the winding short circuit is suppressed, so that the stability of the vehicle behavior is significantly improved when performing the fail-safe operation that repeatedly shorts and releases the winding short circuit. can be secured to In this case, the motor M1 is an example of a first motor that rotates the left wheel, and the inverter 11 is an example of a first inverter that drives the first motor. The motor M2 is an example of a second motor that rotates the right wheel, and the inverter 12 is an example of a second inverter that drives the second motor. Capacitor 21 is an example of a first capacitor, and capacitor 22 is an example of a second capacitor. The charging control circuit 20 is an example of a control device that repeats simultaneous short-circuiting of windings and simultaneous release of short-circuiting of windings.

In addition, the charging control circuit 20 turns on the first one-sided arm of the upper and lower arms of the inverter 11, and turns on the second one-sided arm of the upper and lower arms of the inverter 12 on the same side as the first one-sided arm. This short-circuits both windings of motors M1 and M2 at the same time. Similarly, the charging control circuit 20 turns on the first one-sided arm of the upper and lower arms of the inverter 13, and turns on the second one-sided arm on the same side as the first one-sided arm of the upper and lower arms of the inverter 14. , the windings of both motors M3 and M4 are shorted simultaneously. FIG. 5 illustrates a case where both the first one-sided arm and the second one-sided arm are upper arms. Both the first one-sided arm and the second one-sided arm may be lower arms. Alternatively, the first one-side arm may be the upper arm and the second one-side arm may be the lower arm, or the first one-side arm may be the lower arm and the second one-side arm may be the upper arm.

3, the four capacitors 21 to 24 are connected to a common DC bus 15 connected to the high voltage battery 10 via the contactor 6. As shown in FIG. However, as in FIG. 2, capacitors 21 and 22 are connected to a common DC bus connected to high voltage battery 10 via contactor 6a, and capacitors 23 and 24 are connected to high voltage battery 10 via contactor 6b. may be connected to a common DC bus that That is, the DC busbars connected to the capacitors may be different before and after.

Further, when the timing of winding short circuit and winding short circuit cancellation is synchronized between the left and right motors, the charging control circuit 20 may be included in either one of the left and right ECUs. For example, one of the ECUs 16 and 17 including the charge control circuit 20 turns on or off a winding short-circuit signal 43 (synonymous with the above-described winding short-circuit signal Ss) supplied to the other ECU. . As a result, the windings of the motors M1 and M2 can be short-circuited at the same time, and the winding short-circuiting of the motors M1 and M2 can be released at the same time. Similarly, when either one of the ECUs 18 and 19 includes the charging control circuit 20, one ECU including the charging control circuit 20 outputs the winding short-circuit signal 44 (the above-described winding short-circuit signal) supplied to the other ECU. A signal synonymous with signal Ss) is turned on or off.

<Second comparison mode>
FIG. 6 is a diagram showing a configuration example of a motor drive device in a second comparative embodiment. A motor drive device 100b shown in FIG. 6 is a comparative example for comparison with a motor drive device 102 in a second embodiment described later.

In a drive system including a plurality of inverters that do not have a common DC bus, as in the form shown in FIG. 5d voltage Vdc2 is different. In such a vehicle drive system, simultaneous short-circuiting of the windings between the left and right motors and simultaneous release of the winding short-circuiting are repeated to prevent interruption of the emergency power supply using the capacitors 9a and 9b. , the following problems 2-1 and 2-2 may occur.

(Problem 2-1) In order to maintain the voltages of the capacitors 9a and 9b within a predetermined range, the voltage detection value of the capacitor of one inverter (for example, the capacitor 9a of INV1) is compared with the short-circuit ON threshold and the short-circuit OFF threshold, It is assumed that simultaneous short-circuiting of the windings and release of the short-circuiting of the windings are repeated between INV1 and INV2. In this case, if the capacitance of the capacitor 9b of the INV2 is larger than the capacitance of the capacitor 9a of the INV1 due to variations in capacitor capacitance, the voltage Vdc2 of the capacitor 9b of the INV2 gradually decreases with respect to the short-circuit OFF threshold Vth (OFF). There is a risk (see Figure 7). As a result, it is conceivable that the emergency power supply using the capacitor 9b as a power supply will stop due to the voltage shortage of the capacitor 9b of the INV2, and the INV2 will not be able to maintain the fail-safe operation.

(Problem 2-2) In order to maintain the voltages of the capacitors 9a and 9b within a predetermined range, the voltage detection value of the capacitor of one inverter (for example, the capacitor 9a of INV1) is compared with the short-circuit ON threshold and the short-circuit OFF threshold, It is assumed that simultaneous short-circuiting of the windings and release of the short-circuiting of the windings are repeated between INV1 and INV2. In this case, if the capacitance of the capacitor 9a of INV1 is larger than the capacitance of the capacitor 9b of INV2 due to variations in capacitor capacitance, the voltage Vdc2 of the capacitor 9b of INV2 gradually increases with respect to the short-circuit ON threshold Vth(ON). (See Figure 8). As a result, due to the overvoltage of the capacitor 9b of INV2, the emergency power supply using the capacitor 9b as a power supply may stop, and the main circuit of INV2 may fail, making it impossible to maintain the fail-safe operation in INV2.

Therefore, in order to solve these problems, the motor drive device according to the second embodiment can avoid stoppage of the emergency power supply and It has a configuration that can ensure the stability of the behavior of the vehicle. A motor drive device according to the second embodiment will be described below.

<Second embodiment>
FIG. 9 is a diagram showing a configuration example of a motor drive device according to the second embodiment. A motor drive device 102 shown in FIG. Descriptions of configurations and effects similar to those of the comparative embodiment and the embodiment described above are omitted or simplified by citing the above descriptions. Although the second embodiment shown in FIG. 9 is illustrated for the left and right rear wheels, the description of the second embodiment can be applied to the left and right front wheels.

The ECU 36 controls the inverter 31 that drives the motor M1 that rotates the left rear wheel RL of the vehicle, and the ECU 37 controls the inverter 32 that drives the motor M2 that rotates the right rear wheel RR of the vehicle.

The ECUs 36 and 37 operate using a regular power source 60 (for example, a 12-volt low-voltage battery) having a voltage lower than that of the high-voltage battery 10 as a power source. The ECUs 36, 37 are installed inside or outside the housings of the inverters 31, 32 corresponding thereto.

The inverter 31 is connected to a common DC bus 5c connected to the high voltage battery 10 via a contactor 6c, and the inverter 32 is connected to a common DC bus 5d connected to the high voltage battery 10 via a contactor 6d. there is A capacitor 21 is connected to the DC bus 5c, and a capacitor 22 is connected to the DC bus 5d. Capacitors 21 and 22 are installed inside or outside the housings of inverters 31 and 32 corresponding thereto. Inverter 31 converts DC power supplied from high voltage battery 10 via DC bus 5c into AC power according to a drive signal generated by ECU 36 to drive motor M1. Like the inverter 31, the inverter 32 also drives the motor M2 in accordance with the drive signal generated by the ECU32. Inverters 31 and 32 each have the same configuration as DC/AC converter 202 (see FIG. 1).

Capacitor 21 is discharged when the windings of motor M1 are short-circuited by turning on one arm of all the phases of inverter 11, and is charged when the winding short-circuit of motor M1 is released by turning off the one arm of inverter 11. It is a storage element that is used. Capacitor 22 is discharged when the windings of motor M2 are short-circuited by turning on one arm of all the phases of inverter 12, and is charged when the winding short-circuit of motor M2 is released by turning off the one arm of inverter 12. It is a storage element that is used. Capacitor 21 is an example of a first capacitor, and capacitor 22 is an example of a second capacitor.

In FIG. 9, the charging control circuit 40 is a control device that operates using a regular power source 60 as a power source, like the ECUs 36 and 37 . Note that the charge control circuit 30 may be a control device included in either the ECU 36 or 37 .

The charging control circuit 40 detects the voltage Vdc1 of the capacitor 21 or the DC bus 15c connected to the capacitor 21, and detects the voltage Vdc2 of the capacitor 22 or the DC bus 15d connected to the capacitor 22. Since the capacitor 21 is connected in parallel to the DC bus 5c, the voltage of the DC bus 5c is equal to the voltage of the capacitor 21 if errors such as voltage drop due to wiring resistance are ignored. Since the capacitor 22 is connected in parallel to the DC bus 5d, the voltage of the DC bus 5d is equal to the voltage of the capacitor 22 if errors such as voltage drop due to wiring resistance are ignored.

The charging control circuit 40 is supplied to the ECUs 36 and 37 so that the windings of the motors M1 and M2 are simultaneously short-circuited by the inverters 31 and 32 if either the voltage Vdc1 or the voltage Vdc2 reaches the short-circuit ON threshold first. turns on (active) the winding short-circuit signal Ss. As a result, the ECUs 36 and 37 simultaneously short-circuit the windings of the motors M1 and M2 by the inverters 31 and 32 by detecting the active winding short-circuit signal Ss. On the other hand, the charge control circuit 40 controls the ECUs 36 and 37 so that the inverters 31 and 32 simultaneously release the winding short circuits of the motors M1 and M2 when either the voltage Vdc1 or the voltage Vdc2 reaches the short circuit OFF threshold first. turns off (inactive) the winding short-circuit signal Ss supplied to . As a result, the ECUs 36 and 37 detect the inactive winding short-circuit signal Ss, and simultaneously release the winding short-circuits of the motors M1 and M2 by the inverters 31 and 32 .

Next, a fail-safe operation performed by the motor driving device 102 shown in FIG. 9 when the normal power supply 60 is lost will be described.

When the normal power supply 60 is lost, the ECU 36 operates with power generated by an emergency power supply 75 operating with the capacitor 21 as a power supply, and the ECU 37 operates with power generated with an emergency power supply 85 operating with the capacitor 22 as a power supply. Operate. When the normal power supply 60 is lost, the charging control circuit 40 also uses power generated by an emergency power supply that operates using a capacitor connected to the DC bus (either the capacitor 21 or the capacitor 22, or a capacitor not shown) as a power source. Operate. Further, when the normal power supply 60 is lost, the vehicle controller higher than the ECUs 36, 37 and the charging control circuit 40 turns off the contactors 6c, 6d for fail-safe. When the contactor 6c is turned off, the conduction between the high voltage battery 10 and the DC bus 5c is interrupted, and when the contactor 6d is turned off, the conduction between the high voltage battery 10 and the DC bus 5d is interrupted.

When regular power supply 60 is lost, charging control circuit 40 determines whether one of voltage Vdc1 and voltage Vdc2 reaches the short circuit ON threshold first, and either voltage Vdc1 or voltage Vdc2 reaches the short circuit OFF threshold. Determine whether or not to reach the destination.

Charge control circuit 40 short-circuits both windings of motors M1 and M2 simultaneously when either of voltage Vdc1 and voltage Vdc2 reaches the short-circuit ON threshold first, and either voltage Vdc1 or voltage Vdc2 reaches the short-circuit OFF threshold. is reached first, the simultaneous release of the shorted windings of both motors M1 and M2 is repeated. By simultaneously short-circuiting both windings and simultaneously releasing both winding short-circuits, the timing of winding short-circuiting between motors M1 and M2 can be matched in the same manner as the waveforms shown in FIG. It is possible to match the timing of releasing the winding short circuit between the motors M1 and M2. Therefore, the torque imbalance between the left and right front wheels due to the turning on and off of the winding short-circuit is suppressed, so that the stability of the behavior of the vehicle can be ensured when performing the fail-safe operation that repeats the winding short-circuit and the winding short-circuit release. In this case, the charge control circuit 40 is an example of a control device that repeats simultaneous short-circuiting of windings and simultaneous release of short-circuiting of windings.

Moreover, if either of the voltage Vdc1 and the voltage Vdc2 reaches the short-circuit ON threshold first, the charge control circuit 40 short-circuits the windings of both the motors M1 and M2 at the same time. If one of the two voltages reaches the short-circuit ON threshold first, by short-circuiting both windings at the same time, even if there are variations in the capacities of the capacitors 21 and 22, the voltage of the other voltage is reduced as shown in FIG. can be prevented from gradually rising with respect to the short-circuit ON threshold. Therefore, it is possible to avoid a situation where the emergency power supply 75 is stopped due to the overvoltage of the capacitor 21 and a situation where the emergency power supply 85 is stopped due to the overvoltage of the capacitor 22 can be avoided.

In addition, if either voltage Vdc1 or voltage Vdc2 reaches the short-circuit off threshold first, charge control circuit 40 releases the winding short-circuits of both motors M1 and M2 at the same time. If one of the two voltages reaches the short-circuit OFF threshold first, both winding short-circuits are released at the same time. It is possible to prevent the voltage from gradually dropping to the short circuit OFF threshold. Therefore, it is possible to avoid a situation where the emergency power supply 75 stops due to a voltage shortage of the capacitor 21 and a situation where the emergency power supply 85 stops due to a voltage shortage of the capacitor 22 can be avoided.

By the way, the charge control circuit 40 causes the inverters 31 and 32 to simultaneously short-circuit both windings when one of the voltages Vdc1 reaches the short-circuit ON threshold, and the inverters 31 and 32 when the voltage Vdc1 reaches the short-circuit OFF threshold. Releasing both winding shorts at the same time may be repeated. In this case, when the other voltage Vdc2 is higher than the short-circuit ON threshold, the charge control circuit 40 alternately turns on and off the upper and lower arms of the inverter 32 as shown in FIG. 10, thereby short-circuiting the winding of the motor M2. . Hereinafter, such control that repeats simultaneous short-circuiting and simultaneous release based on one voltage and alternately turns on and off the upper and lower arms when the other voltage is higher than the short-circuit ON threshold is referred to as "alternating short-circuit control". By executing the alternate short-circuit control, even if the voltage Vdc2 exceeds the short-circuit ON threshold value as shown in FIG. 8, the surplus energy accumulated in the capacitor 22 can be quickly consumed by the switching losses of both the upper and lower arms. Therefore, it is possible to avoid a situation where the emergency power supply 85 stops due to the overvoltage of the capacitor 22 .

In the alternate short-circuit control, the charging control circuit 40 continuously turns on one of the upper and lower arms of the inverter 31 (the upper arm in the case of FIG. 10) when one of the voltages Vdc1 reaches the short-circuit ON threshold. It is preferable to short-circuit the windings of the motor M1.

In alternate short-circuit control, when the difference between voltage Vdc1 and voltage Vdc2 is large, charge control circuit 40 preferably increases the frequency of alternately turning on and off the upper and lower arms of inverter 32 compared to when the difference is small. Thereby, even if the difference becomes large, the difference can be quickly reduced.

It should be noted that in the above description of the alternate short-circuit control, the alternate short-circuit control may be performed by replacing the voltage Vdc1 with the voltage Vdc2.

FIG. 11 is a diagram showing a first detailed configuration example of the motor drive device according to the second embodiment. A motor driving device 102a shown in FIG. 11 is an example of the motor driving device 102 shown in FIG.

In FIG. 11, the motor driving device 102a includes two inverters 31 and 32 for driving left and right wheels. The inverters 31 and 32 have ECUs 36 and 37, DC/AC conversion circuits 51 and 52, and capacitors 21 and 22, respectively. The ECUs 36, 37 have motor control circuits 71, 81, fail-safe logic circuits 72, 82, upper arm drive circuits 73, 83, lower arm drive circuits 74, 84, and emergency power supplies 75, 85, respectively. FIG. 11 illustrates a form in which the inverter 31 includes a charge control circuit 41 corresponding to the charge control circuit 40 described above.

The motor control circuits 71 and 81 generate pulse width modulation signals according to operation commands S1 and S2 respectively from the host vehicle controller. The upper arm drive circuits 73, 83 and the lower arm drive circuits 74, 84 drive the switching elements in the DC/AC conversion circuits 51, 52 by gate drive signals generated according to the pulse width modulated signals. As a result, desired motor torques are generated in the motors M1 and M2.

Electric power from the normal power supply 60 is supplied to each circuit except for the DC/AC conversion circuits 51 and 52 (also referred to as main circuits) via the normal power supply systems 61 and 62 . Electric power generated by the emergency power supplies 75 and 85 is supplied to the charging control circuit 41, the fail-safe logic circuits 72 and 82, the upper arm drive circuits 73 and 83 and the lower arm drive circuit 74 via the emergency power supply systems 76 and 86. , 84.

For example, when detecting an abnormal drop in the voltages LV1 and LV2 of the normal power supply 60, the charging control circuit 41 detects that the normal power supply 60 has been lost. When the loss of utility power supply 60 is detected, charge control circuit 41 detects the respective capacitor voltages Vdc1 and Vdc2 and compares the detected values with predetermined short-circuit ON and short-circuit OFF thresholds. The charge control circuit 41 outputs command signals 46, 48 for turning on or off the winding short circuit by the upper arm or command signals 47, 49 for turning on or off the winding short circuit by the lower arm to respective fail-safe logic circuits 72. , 82 at the same time. A fail-safe logic circuit 72, which receives command signals 46 and 47, generates a gate drive signal for each arm corresponding to a shorted winding of motor M1. A fail-safe logic circuit 82, which receives command signals 48 and 49, generates a gate drive signal for each arm corresponding to a shorted winding of motor M2.

FIG. 16 is a diagram showing a detailed configuration example of a charge control circuit 41a, which is a first example of the charge control circuit 41 of FIG. FIG. 17 is a truth table for logic circuit 65 of FIG. "H" represents high level and "L" represents low level. The charging control circuit 41a shown in FIG. 16 receives the voltage detection values (Vdc1, Vdc2) of the capacitors of each inverter and the voltages (LV1, LV2) of the normal power supply 60, and short-circuits the windings in the upper or lower arm of each inverter. command signals 46 to 49 are output from the AND gate 69 . 16 and 17 show an example of short-circuiting the windings in the lower arm.

The charge control circuit 41a compares Vdc1 and Vdc2 with the short-circuit ON threshold and the short-circuit OFF threshold in the hysteresis comparators 63 and 64, respectively. Each output of the hysteresis comparators 63 and 64 is input to the logic circuit 65 (inputs A and B). Logic circuit 65 sets the level of output Q input to AND gate 69 according to the truth table shown in FIG. On the other hand, the voltages (LV1, LV2) of normal power supply 60 are input to NAND gate 70 . The output of logic circuit 65 and the output of NAND gate 70 are input to AND gate 69 .

Therefore, when either Vdc1 or Vdc2 first exceeds the short-circuit ON threshold with the winding short-circuit turned off and the loss of the voltage (LV1, LV2) of the main power supply 60 is detected, all the lower arms are turned off. A high level command signal 47, 49 is output to turn on the winding short circuit. On the other hand, if either Vdc1 or Vdc2 first falls below the short-circuit OFF threshold when the winding short-circuit is on, low-level command signals 47 and 49 are output to turn off the winding short-circuiting of all the lower arms. .

FIG. 12 is a diagram showing a detailed configuration example of a charge control circuit 41b, which is a second example of the charge control circuit 41 of FIG. The charging control circuit 41b receives as input the voltage detection values (Vdc1, Vdc2) of the capacitors of each inverter and the voltages (LV1, LV2) of the normal power supply 60, and a command signal 46 for shorting the windings in the upper or lower arm of each inverter. . . 49 are output from logic gates 26, 27, 28 and 29. FIG.

The charging control circuit 41b uses the hysteresis comparators 63 and 64 to compare Vdc1 and Vdc2 with the short-circuit ON threshold and the short-circuit OFF threshold, respectively. Each output of hysteresis comparators 63 and 64 is input to AND gate 66 . The output of AND gate 69 is input to logic gates 26 , 27 , 28 and 29 .

Therefore, when either Vdc1 or Vdc2 falls below the short-circuit OFF threshold, command signals 46 to 49 are output to turn off the winding short-circuit. On the other hand, when both Vdc1 and Vdc2 exceed the short-circuit ON threshold and the loss of the voltage (LV1, LV2) of the normal power supply 60 is detected, command signals 46 to 49 are output to turn on the winding short-circuit. .

Further, the charge control circuit 41b calculates a deviation D1 obtained by subtracting the voltage Vdc2 from the voltage Vdc1 using the subtractor 91, and a deviation D2 obtained by subtracting the voltage Vdc1 from the voltage Vdc2 using the subtractor 92. After the deviation D1 is converted to a non-negative value by a processing circuit 93 for zeroing negative values, PI control 95 is applied to the non-negative value to generate a control voltage V1. Control voltage V1 is converted to frequency F1 by voltage frequency converter 97 and input to logic gates 26 and 27 . The deviation D2 is converted to a non-negative value by a processing circuit 94 for zeroing negative values, and then PI control 96 is applied to the non-negative value to generate a control voltage V2. Control voltage V2 is converted to frequency F2 by voltage frequency converter 98 and input to logic gates 28 and 29 .

Therefore, if Vdc1 is higher than Vdc2, command signals 46 and 47 are output to alternately turn on and off the upper and lower arms of inverter 31 to short-circuit the windings. On the other hand, if Vdc2 is higher than Vdc1, command signals 48 and 49 are output to alternately turn on and off the upper and lower arms of inverter 32 to short-circuit the windings.

FIG. 13 is a diagram showing a second detailed configuration example of the motor drive device according to the second embodiment. A motor driving device 102b shown in FIG. 13 is an example of the motor driving device 102 shown in FIG. A motor driving device 102b in FIG. 13 differs from the motor driving device 102a in FIG. 11 in that it includes discharge circuits 35a and 35b. The configuration similar to that of the motor driving device 102a of FIG. 11 is omitted or simplified by citing the above description. FIG. 13 illustrates a form in which the inverter 31 includes a charge control circuit 42 corresponding to the charge control circuit 40 described above.

The discharge circuit 35a is a first discharge circuit that discharges the capacitor 21 by switching the first transistor 39a, and the discharge circuit 35b is a second discharge circuit that discharges the capacitor 22 by switching the second transistor 39b. be. The discharge circuit 35a is a rapid discharge circuit connected in parallel with the capacitor 21, and has a series circuit of a resistive element 38a and a transistor 39a. The discharge circuit 35b is a rapid discharge circuit connected in parallel with the capacitor 22, and has a series circuit of a resistive element 38b and a transistor 39b.

For example, when detecting an abnormal drop in the voltages LV1 and LV2 of the normal power supply 60, the charging control circuit 42 detects that the normal power supply 60 has been lost. When the loss of utility power supply 60 is detected, charge control circuit 42 detects the respective capacitor voltages Vdc1 and Vdc2 and compares the detected values to predetermined short-circuit on and short-circuit off thresholds. The charge control circuit 42 simultaneously outputs command signals 77, 87 for turning on or off the winding short circuit by the upper arm or the lower arm to the respective fail-safe logic circuits 72, 82 respectively. Fail-safe logic circuit 72, which receives command signal 77, generates a gate drive signal for each arm corresponding to a shorted winding of motor M1. A fail-safe logic circuit 82, which receives a command signal 87 as an input, generates a gate drive signal for each arm corresponding to a shorted winding of motor M2.

The charge control circuit 42 operates a discharge circuit that discharges the capacitor having the higher voltage value between the voltage Vdc1 and the voltage Vdc2, and lowers the voltage of the higher voltage value.

FIG. 14 is a diagram illustrating a detailed configuration example of the charging control circuit 42 of FIG. 13. As shown in FIG. The charging control circuit 42 receives the voltage detection values (Vdc1, Vdc2) of the capacitors of each inverter and the voltages (LV1, LV2) of the normal power supply 60, and receives a command signal 77 for shorting the windings in the upper or lower arm of each inverter. , 87 are output from the AND gate 80 .

The charging control circuit 42 compares Vdc1 and Vdc2 with the short-circuit ON threshold and the short-circuit OFF threshold in the hysteresis comparators 63 and 64, respectively. Each output of hysteresis comparators 63 and 64 is input to AND gate 89 . AND gate 89 outputs a high level signal when both Vdc1 and Vdc2 exceed the short-circuit ON threshold. The output of AND gate 89 and the output of NOT AND gate 70 are input to AND gate 80 .

Therefore, when both Vdc1 and Vdc2 exceed the short-circuit ON threshold and the loss of the voltage (LV1, LV2) of the normal power supply 60 is detected, command signals 77 and 87 for turning on the winding short-circuit are output. .

Further, charging control circuit 42 calculates deviation D1 obtained by subtracting voltage Vdc2 from voltage Vdc1 using subtractor 91 and deviation D2 obtained by subtracting voltage Vdc1 from voltage Vdc2 using subtractor 92 . After the deviation D1 is converted to a non-negative value by a processing circuit 93 for zeroing negative values, PI control 95 is applied to the non-negative value to generate a control voltage V1. The control voltage V1 is compared with the carrier wave 79 by the comparator 78 to output the pulse width modulated discharge command G1. The deviation D2 is converted to a non-negative value by a processing circuit 94 for zeroing negative values, and then PI control 96 is applied to the non-negative value to generate a control voltage V2. The control voltage V2 is compared with the carrier wave 79 by the comparator 88 to output a pulse width modulated discharge command G2.

Therefore, if Vdc1 is higher than Vdc2, discharge command G1 is applied to discharge circuit 35a of inverter 31. FIG. The discharging circuit 35a rapidly discharges the electric charge of the capacitor 21 by the transistor 39a which is turned on and off according to the discharge command G1 (see FIG. 15). On the other hand, if Vdc2 is higher than Vdc1, a discharge command G2 is given to the discharge circuit 35b of the inverter 32. FIG. The discharge circuit 35b rapidly discharges the electric charge of the capacitor 22 by the transistor 39b that is turned on and off according to the discharge command G2.

Although the motor drive device has been described above with reference to the embodiments, the present invention is not limited to the above embodiments. Various modifications and improvements such as combination or replacement with part or all of other embodiments are possible within the scope of the present invention.

1 to 4 Inverters 1a to 1d Emergency power supplies 5a to 5d DC buses 6, 6a to 6d Contactors 7a to 7d ECU
8 vehicle controller 9a-9d capacitor 10 high-voltage battery 11-14, 31, 32 inverter 15 DC bus 16-19 ECU
20 charge control circuits 21 to 24 capacitors 35a, 35b discharge circuits 36, 37 ECU
40 charging control circuits 41, 41a, 41b, 42 charging control circuits 51, 52 DC/AC conversion circuit 60 common power supplies 63, 64 hysteresis comparators 100a, 100b, 101, 102, 102a, 102b motor driving device

Claims (8)

a first inverter that drives a first motor that rotates the left wheel of the vehicle;
a first capacitor that is discharged when the windings of the first motor are short-circuited by the first inverter and charged when the winding short-circuiting of the first motor is removed by the first inverter; ,
a second inverter that drives a second motor that rotates the right wheel of the vehicle;
a second capacitor that is discharged when the windings of the second motor are short-circuited by the second inverter and charged when the winding short-circuits of the second motor are removed by the second inverter; ,
When the voltage of the DC bus commonly connected to the first capacitor and the second capacitor reaches a first threshold, the first motor and the second capacitor are connected by the first inverter and the second inverter. 2 motors at the same time, and when the voltage of the DC bus reaches a second threshold lower than the first threshold, the first inverter and the second inverter operate the first inverter. and a control device that repeats simultaneously releasing short-circuited windings of both the motor and the second motor. a first inverter that drives a first motor that rotates the left wheel of the vehicle;
a first capacitor that is discharged when the windings of the first motor are short-circuited by the first inverter and charged when the winding short-circuiting of the first motor is removed by the first inverter; ,
a second inverter that drives a second motor that rotates the right wheel of the vehicle;
a second capacitor that is discharged when the windings of the second motor are short-circuited by the second inverter and charged when the winding short-circuits of the second motor are removed by the second inverter; ,
If the voltage of either the first capacitor or the second capacitor reaches the first threshold first, the first motor and the second motor are controlled by the first inverter and the second inverter. If the voltage of either the first capacitor or the second capacitor reaches a second threshold lower than the first threshold first, the first inverter and a control device that repeats releasing short-circuited windings of both the first motor and the second motor by the second inverter at the same time. a first inverter that drives a first motor that rotates one of left and right wheels of the vehicle;
a first capacitor that is discharged when the windings of the first motor are short-circuited by the first inverter and charged when the winding short-circuiting of the first motor is removed by the first inverter; ,
a second inverter that drives a second motor that rotates the other of the left and right wheels of the vehicle;
a second capacitor that is discharged when the windings of the second motor are short-circuited by the second inverter and charged when the winding short-circuits of the second motor are removed by the second inverter; ,
When the voltage of the first capacitor reaches a first threshold, the windings of both the first motor and the second motor are simultaneously short-circuited by the first inverter and the second inverter, and the When the voltage of the first capacitor reaches a second threshold lower than the first threshold, the winding of both the first motor and the second motor is controlled by the first inverter and the second inverter. A control device that repeats releasing the line short circuit at the same time,
When the voltage of the second capacitor is higher than the first threshold, the control device alternately turns on and off the upper and lower arms of the second inverter to short-circuit the windings of the second motor. motor drive. When the voltage of the first capacitor reaches a first threshold value, the control device continuously turns on one of the upper and lower arms of the first inverter to turn on the windings of the first motor. 4. The motor drive device according to claim 3, wherein the short circuit of When the difference between the voltage of the first capacitor and the voltage of the second capacitor is large, the control device controls the frequency for alternately turning on and off the upper and lower arms of the second inverter compared to when the difference is small. 5. The motor driving device according to claim 3 or 4, wherein . a first discharge circuit that discharges the first capacitor by switching a first transistor;
a second discharge circuit that discharges the second capacitor by switching the second transistor;
The control device operates a discharge circuit that discharges a capacitor having a higher voltage value between the voltage of the first capacitor and the voltage of the second capacitor, and reduces the voltage of the higher voltage value. 3. The motor driving device according to claim 1 or 2, which allows The control device uses a first one-sided arm of the upper and lower arms of the first inverter and a second one-sided arm on the same side as the first one-sided arm of the upper and lower arms of the second inverter, 7. The motor driving device according to any one of claims 1 to 6, wherein the windings of both the first motor and the second motor are short-circuited simultaneously. 8. The motor driving device according to claim 7, wherein both said first one-sided arm and said second one-sided arm are upper arms.

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