JP7183614B2 - Drive control device for vehicle drive system - Google Patents

Description

The present invention relates to a drive control device applied to a vehicle drive system.

Japanese Patent Application Laid-Open No. 2002-200000 describes an electric vehicle that includes a first motor (electric motor) that drives the front wheels of the vehicle and a second motor that drives the rear wheels of the vehicle. In this electric vehicle, the motor control device distributes the required torque required for the vehicle and drives and controls the first motor and the second motor. In order to suppress heat generated by driving the motors, the motor control device sets a reference torque for each motor based on the temperature of each motor. The torque distribution control is executed to reduce the drive torque in one motor and to increase the drive torque in the other motor.

JP 2012-95378 A

In a vehicle equipped with a plurality of electric motors for driving wheels, it is preferable to reduce the unevenness in temperature of each electric motor as much as possible in order to equalize the characteristics and life of each electric motor. In the technique disclosed in Patent Document 1, torque distribution control is executed based on whether or not the driving torque of each electric motor has exceeded the reference torque for a predetermined period of time or longer. .

SUMMARY OF THE INVENTION In view of the above, it is an object of the present invention to provide a drive control device that is applied to a drive system that includes a plurality of electric motors for driving a vehicle, and that can reduce unevenness in the temperature of each electric motor.

The present invention provides a drive control device for driving a drive system of a vehicle driven by a plurality of electric motors. This drive control device includes a temperature acquisition unit that acquires temperatures of the plurality of electric motors, and a temperature difference between the plurality of electric motors based on the temperatures of the plurality of electric motors acquired by the temperature acquisition unit. A drive control device comprising: a torque distribution unit that distributes a required torque required for the vehicle to each of the electric motors. And prepare.

According to the present invention, when the torque distribution unit distributes the required torque required for the vehicle to the plurality of electric motors, the temperature difference between the plurality of electric motors based on the temperatures of the plurality of electric motors acquired by the temperature acquisition unit is small. Distribute so that As a result, it is possible to reduce unevenness in temperature among the electric motors, thereby suppressing uneven deterioration of the characteristics and life of the electric motors.

1 is a schematic diagram of a drive system controlled by a drive control device according to a first embodiment; FIG. 1 is a schematic diagram of a drive control device according to a first embodiment; FIG. 4 is a flowchart of drive control processing according to the first embodiment; 4 is a time chart of drive control according to the first embodiment; 8 is a flowchart of drive control processing according to the second embodiment; 10 is a flowchart of drive control processing according to the third embodiment; 14 is a flowchart of drive control processing according to the fourth embodiment; 14 is a flowchart of drive control processing according to the fifth embodiment;

(First embodiment)
FIG. 1 shows a drive system 10 for a vehicle 20 according to this embodiment. The drive system 10 is mounted on a vehicle 20 that is an electric vehicle (EV vehicle), and can drive drive shafts 21 and 22 of the vehicle 20 . The drive system 10 includes a storage battery 11, MGs 12 and 13, which are drive motor generators (motor generators: MG), inverters 14 and 15, and an ECU 40. FIG. 2 shows a schematic diagram of a specific configuration of the ECU 40. As shown in FIG.

The storage battery 11 is a secondary battery, more specifically, a lithium ion storage battery with an output voltage of about 200 to 300V, for example.

First MG 12 is connected to storage battery 11 via first inverter 14 . Second MG 13 is connected to storage battery 11 via second inverter 15 . When the MGs 12 and 13 operate as generators, the inverters 14 and 15 can convert the generated AC power into DC power and store it in the storage battery 11 . When MGs 12 and 13 operate as electric motors, inverters 14 and 15 can convert DC power output from storage battery 11 into AC power to operate MGs 12 and 13 .

First MG 12 is connected to first drive shaft 21 arranged in front of vehicle 20 . Wheels 31 and 32 that are front wheels of the vehicle 20 are connected to both ends of the first drive shaft 21 . The second MG 13 is connected to a second drive shaft 22 arranged behind the vehicle 20 . Wheels 33 and 34 that are rear wheels of the vehicle 20 are connected to both ends of the second drive shaft 22 .

The MGs 12 and 13 convert the rotational energy of the wheels 31 to 34 into electric power when operating as generators, and convert the electric power supplied from the storage battery 11 into rotational energy when operating as motors to drive the drive shaft 21. , 22.

The wheels 31-34 are provided with braking devices 35-38, respectively. The braking devices 35-38 are hydraulic brakes, and apply braking pressure to the corresponding wheels 31-34 to generate braking torque and brake the wheels 31-34.

The sensors 50 are conventionally known sensors capable of detecting the state of the vehicle 20 and the state of the surroundings of the vehicle 20. Specifically, the sensors 50 include an accelerator sensor 51, a vehicle speed sensor 52, a first temperature sensor 53, a second temperature A sensor 54 and the like can be exemplified. A first temperature sensor 53 is installed in the first MG 12 and can detect the temperature of the first MG. A second temperature sensor 54 is installed in the second MG 13 and can detect the temperature of the second MG 13 .

The ECU 40 is a drive control device that controls each component of the drive system 10 such as the storage battery 11, the MGs 12 and 13, the inverters 14 and 15, and the like. The ECU 40 is applied to a drive system 10 that includes a first MG 12 that drives front wheels 31 and 32 of the vehicle 20 and a second MG 13 that drives rear wheels 33 and 34 .

The ECU 40 can acquire information from sensors 50 mounted on the vehicle 20 and output control signals to the storage battery 11, the MGs 12 and 13, the inverters 14 and 15, and the like. Further, the ECU 40 can acquire information input from the outside of the vehicle 20 or from a driving support device through an information terminal (not shown) mounted on the vehicle 20 .

The ECU 40 is mainly composed of a microcomputer comprising a CPU, a ROM, a RAM, a backup RAM, an I/O, etc. (none of which are shown), and executes various control programs stored in the ROM. Each function described in the document can be realized.

The ECU 40 includes a temperature acquisition section 41 , a temperature prediction section 42 , a torque calculation section 43 , a torque distribution section 44 and a control command section 45 .

The temperature acquisition unit 41 acquires a first temperature T1 that is the temperature of the first MG 12 and a second temperature T2 that is the temperature of the second MG 13 . The temperature acquisition unit 41 may use the measured values input from the first temperature sensor 53 and the second temperature sensor 54 as the first temperature T1 and the second temperature T2. Further, the temperature acquisition unit 41 may use predicted values of the first temperature T1 and the second temperature T2 predicted by the temperature prediction unit 42, which will be described later, as the first temperature T1 and the second temperature T2. Furthermore, the temperature acquisition unit 41 detects and predicts the first temperature T1 and the second temperature T2 based on the operation input by the driver or the like, the driving situation of the vehicle 20, the traveling route situation, and the like. It may be configured to be able to select which one to use.

The temperature prediction unit 42 predicts temporal changes in the first temperature T1 and the second temperature T2. Specifically, for example, the detected value (actually measured value) of the first temperature T1 detected by the first temperature sensor 53, the detected value (actually measured value) of the second temperature T2 detected by the second temperature sensor 54, the navigation system, etc. conditions of the traveling route of the vehicle 20, the outside temperature, the conditions of the traveling road on which the vehicle 20 is traveling, such as the slope and curvature of the traveling road, the SOC of the storage battery 11, the vehicle speed, the accelerator opening, the vehicle interior temperature, etc. It is possible to calculate the predicted value of the first temperature T1 and the predicted value of the second temperature T2 corresponding to the elapsed time from the current time based on the running condition of the vehicle 20 and the like. Specifically, for example, the first temperature T1 and the second temperature T2 can be predicted by predicting the time change of the required torque RC from the travel history of the vehicle 20 . Further, for example, the first temperature T1 and the second temperature T2 can be predicted by calculating the cooling rate of the MGs 12 and 13 from the vehicle interior temperature and the outside air temperature of the vehicle 20 .

The torque calculator 43 calculates a required torque RC required when the vehicle 20 travels. When powering the MGs 12 and 13, the drive torque required to drive the drive shafts 21 and 22 can be calculated as the required torque RC based on the driving conditions of the vehicle 20, the conditions of the road, and the like. . When the MGs 12 and 13 are regeneratively operated, the braking torque required to brake the drive shafts 21 and 22 can be calculated as the required torque RC based on the driving conditions of the vehicle 20, the conditions of the road, and the like. .

The torque distribution unit 44 distributes the required torque RC calculated by the torque calculation unit 43 to a first rotation torque R1 with which the first MG 12 rotates and a second rotation torque R2 with which the second MG 13 rotates. For example, when the required torque RC is secured by only the first rotational torque R1 and the second rotational torque R2, the first rotational torque R1 and the second rotational torque R2 are determined so as to satisfy RC=R1+R2. When distributing torque, each torque value may be calculated, or a distribution ratio may be calculated for each torque. Note that the rotational torque of the MGs 12, 13 includes both the drive torque output by the MGs 12, 13 during power running and the regenerative torque input to the MGs 12, 13 during regenerative operation. Hereinafter, in this specification, drive torque will be described as positive rotational torque, and regenerative torque will be described as negative rotational torque.

The torque distribution unit 44 determines a "temperature difference mode" for determining torque distribution so that the temperature difference dT between the first temperature T1 and the second temperature T2 is small, and determines torque distribution regardless of the temperature difference dT. "Normal mode" is executable. The torque distribution unit 44 may be configured to be selectable in which mode to determine torque distribution.

In the temperature difference mode, the torque distribution unit 44 rotates the first MG 12 with respect to the required torque RC required of the vehicle 20 so that the temperature difference dT between the first temperature T1 and the second temperature T2 becomes small. The distribution between the first rotational torque R1 and the second rotational torque R2 with which the second MG 13 rotates is determined.

The torque distribution unit 44 is configured to select a higher temperature high temperature electric motor and a lower low temperature electric motor from among the first MG 12 and the second MG 13 based on the first temperature T1 and the second temperature T2. good too. Furthermore, the torque distribution unit 44 reduces the rotational torque of the high-temperature electric motor so that the temperature difference dT between the first temperature T1 and the second temperature T2 becomes small, and according to the reduction amount, the rotational torque of the low-temperature electric motor may be configured to determine the amount of increase in

Specifically, for example, when the first temperature T1 is higher than the second temperature T2 (T1>T2), the first MG 12 is selected as the high temperature motor, and the second MG 13 is selected as the low temperature motor. Then, the torque distribution unit 44 reduces the first rotation torque R1 of the first MG12 and increases the second rotation torque R2 of the second MG13. The torque distribution unit 44 determines the amount of increase of the second rotational torque R2 so as to complement the amount of reduction of the first rotational torque R1. For example, the torque distribution is determined so that the amount of reduction in the first rotation torque R1 and the amount of increase in the second rotation torque R2 are substantially the same. As a result, the torque distribution can be determined so as to secure the required torque RC and reduce the temperature difference dT.

On the condition that the temperature difference dT is equal to or greater than a predetermined temperature difference threshold value A (dT≧A), the torque distribution unit 44 reduces the temperature difference dT by reducing the first rotational torque R1 and the required torque RC. It may be configured to determine the distribution with the second rotation torque R2. Furthermore, the torque distribution unit 44 may be configured to change the temperature difference threshold value A depending on which of the first temperature T1 and the second temperature T2 is higher. For example, depending on the installation positions of the MGs 12 and 13 in the vehicle 20, the cooling rates of the MGs 12 and 13 may differ. In this case, when the cooling rate of the first MG 12 is faster than the cooling rate of the second MG 13, the temperature difference threshold A is set large when the first temperature T1 is higher than the second temperature T2, and the first temperature T1 It is preferable to set the temperature difference threshold value A small when the temperature is lower than the second temperature T2.

The torque distribution unit 44 sets temperature thresholds B1 and B2 for the first temperature T1 or the second temperature T2, and selects the temperature difference mode or the normal mode based on comparison with the temperature thresholds B1 and B2. may be configured to Specifically, for example, the torque distribution unit 44 sets the first temperature T1 to a predetermined first temperature threshold B1 or higher (T1≧B1), and the second temperature T2 to a predetermined second temperature threshold B2 or higher ( If T2≧B2), the temperature difference mode may be selected, and otherwise the normal mode may be selected. The first temperature threshold B1 and the second temperature threshold B2 can be set according to the temperature characteristics of the MGs 12 and 13. When the cooling rate of the first MG12 is faster than the cooling rate of the second MG13, the first temperature threshold B1 can be set higher than the second temperature threshold B2.

Alternatively, one temperature threshold B may be used to compare the first temperature T1 and the second temperature T2. In this case, the temperature threshold B may be changed depending on which of the first temperature T1 and the second temperature T2 is higher. For example, when the cooling rate of the first MG 12 is faster than the cooling rate of the second MG 13, if the first temperature T1 is higher than the second temperature T2, the temperature threshold B is set to a higher temperature, and the first temperature T1 is If the temperature is lower than the second temperature T2, the temperature threshold B may be set to a lower temperature.

The torque distribution unit 44 sets torque ranges (first rotation torque range, second rotation torque range) required to ensure running stability of the vehicle 20 for the first rotation torque R1 and the second rotation torque R2. You may In this case, torque distribution is determined so that the first rotational torque R1 is within the first rotational torque range and the second rotational torque R2 is within the second rotational torque range. The torque range required to ensure the running stability of the vehicle 20 is calculated based on the driving conditions of the vehicle 20, the conditions of the travel route, and the like. Note that when the distribution of the first rotational torque R1 and the second rotational torque R2 is calculated by the torque distribution ratio X (for example, X=R1/R2), the first rotational torque range and the second rotational torque range are respectively Instead of setting, the range of the torque distribution ratio X may be set.

For example, when the vehicle 20 slips, control is performed to reduce the driving torque of the drive shafts 21 and 22 in order to suppress slipping, so the first rotational torque range and the second rotational torque range are set to relatively low ranges. be.

Also, the first rotational torque range and the second rotational torque range are set according to the inclination angle and curvature of the travel route and the posture of the vehicle 20 corresponding thereto. For example, when the vehicle 20 climbs a slope, the first rotational torque range is set relatively low so that the second rotational torque R2 that drives the rear wheels 33 and 34 is increased, and the second rotational torque range is compared. set high. Conversely, when the vehicle 20 descends a slope, the first rotational torque range is set relatively high and the second rotational torque range is set relatively high so that the first rotational torque R1 that drives the front wheels 31 and 32 is increased. Set relatively low.

In addition, when the drive system is configured to be able to independently control the rotational torque of the left and right wheels, when the vehicle travels on a curved road, the torque driving the wheels on the outside corner of the curve is controlled by the torque on the wheels on the inside corner of the curve. The torque range may be determined to be greater than the torque for driving the . Specifically, using the vehicle 20, when the vehicle 20 travels on a curved road where the vehicle 20 turns right, the torque range is set so that the drive torque of the wheels 31, 33 on the outside corner is greater than that of the wheels 32, 34 on the inside corner. may be set.

The requested torque RC may also be calculated as a braking torque. Hereinafter, in this specification, the braking torque will be described as a negative torque. In this case, the torque distributor 44 may determine the distribution of the braking torque with which the braking devices 35-38 respectively brake the wheels 31-34. Regarding the braking torque, the braking torque of the braking devices 35 and 36 for braking the front wheels 31 and 32 is defined as a first braking torque RB1, and the braking torque of the braking devices 37 and 38 for braking the rear wheels 33 and 34 is defined as a first braking torque RB1. Assuming the second braking torque RB2, the braking torques RB1 and RB2 can be calculated from the following equation (1).
RB1+RB2=RC-(R1+R2) (1)

The control command unit 45 transmits a control command signal to each component of the drive system 10 such as the storage battery 11, the MGs 12 and 13, the inverters 14 and 15, and controls each component. For example, a torque command signal for each of the MGs 12 and 13 is created based on the required torque calculated by the torque calculator 43 and the torque distribution determined by the torque distributor 44, and output to the inverters 14 and 15 and the like. Thereby, the rotational torques R1 and R2 of the MGs 12 and 13 can be controlled.

FIG. 3 shows a flowchart of drive control processing executed by the ECU 40 .

First, in step S101, the required torque RC in the vehicle 20 is calculated. The ECU 40 calculates the torque required to drive the drive shafts 21 and 22 as the required torque RC based on the driving conditions of the vehicle 20, the conditions of the road, and the like. After that, the process proceeds to step S102.

In the next step S102, the first temperature T1 and the second temperature T2 are obtained. Specifically, for example, the value detected by the first temperature sensor 53 is obtained as the first temperature T1, and the value detected by the second temperature sensor 54 is obtained as the second temperature T2. After that, the process proceeds to step S103.

In step S103, the temperature difference dT between the first temperature T1 and the second temperature T2 is calculated. As shown in the following formula (2), the temperature difference dT is calculated as the absolute value abs (T1-T2) of the difference between the first temperature T1 and the second temperature T2. After that, the process proceeds to step S108.
dT=abs(T1-T2) (2)

In step S108, it is determined whether or not the temperature difference dT is equal to or greater than the temperature difference threshold A. If dT.gtoreq.A, the process proceeds to step S109, where it is determined to perform torque distribution in the temperature difference mode. If dT<A, the process proceeds to step S110, where it is determined to perform torque distribution in the normal mode.

In step S109, the torque distribution is determined by the temperature difference mode. That is, the required torque RC is distributed to the MGs 12 and 13 so that the temperature difference dT becomes small. More specifically, the ratio of the first rotational torque R1 and the second rotational torque R2 to the required torque RC is determined so as to satisfy the following formula (3).
RC=R1+R2 (3)

Specifically, for example, the current first rotation torque R1 and second rotation torque R2 are acquired, and when the first temperature T1 is higher than the second temperature T2 (T1>T2), the first rotation A reduction amount of the torque R1 and an increase amount of the second rotation torque R2 are calculated. Torque distribution is determined so that the amount of reduction in the first rotation torque R1 and the amount of increase in the second rotation torque R2 are substantially the same. Conversely, when the first temperature T1 is lower than the second temperature T2 (T1<T2), the amount of increase in the first rotation torque R1 and the amount of decrease in the second rotation torque R2 are calculated. Torque distribution is determined so that the amount of increase in the first rotation torque R1 and the amount of decrease in the second rotation torque R2 are substantially the same.

A control command signal created based on the torque distribution determined in step S109 is output to the inverters 14, 15, etc. to control the rotational torques R1, R2 of the MGs 12, 13 so as to reduce the temperature difference dT. be able to. After step S109, the process ends.

In step S110, torque distribution is determined in normal mode. That is, the torque distribution is determined in consideration of drivability such as the traveling speed, acceleration, and fuel consumption of the vehicle 20, as in the conventionally known technique. After step S110, the process ends.

FIG. 4 shows a time chart of the drive control process according to the flowchart of FIG. In FIG. 4A, the horizontal axis indicates time, and the vertical axis indicates torque. The vertical width of the region indicated by reference number 61 indicates the first rotational torque R1, and the vertical width of the region indicated by reference number 62 indicates the second rotational torque R2. In FIG. 4B, the horizontal axis indicates time, and the vertical axis indicates the temperature of MGs 12 and 13. In FIG. The dashed line indicated by reference number 63 is the first temperature T1, and the solid line indicated by reference number 64 is the second temperature T2.

During the period from time s0 to s1, as shown in FIG. 4B, the first temperature T1 and the second temperature T2 are approximately the same, and dT=0. Therefore, torque distribution is determined in normal mode. As shown in FIG. 4A, the first MG 12 and the second MG 13 are driven with the same rotational torque, and R1=R2=RC/2.

As shown in FIG. 4B, after time s1, the first temperature T1 becomes higher than the second temperature T2 (T1≧T2). However, since the temperature difference dT is less than the temperature difference threshold A, torque distribution is determined in normal mode. From time s1 to s2, temperature difference dT (=T1-T2) increases over time, and at time s2, temperature difference dT reaches temperature difference threshold A (dT=A).

At time s2, the condition that the temperature difference dT is equal to or greater than the temperature difference threshold A is satisfied, so the torque distribution mode switches from the normal mode to the temperature difference mode. As a result, as shown in FIG. 4A, the first rotational torque R1 of the first MG12, which is the high-temperature electric motor, is reduced, and the second rotational torque R2 of the second MG13, which is the low-temperature electric motor, is increased. By setting the amount of decrease in the first rotational torque R1 and the amount of increase in the second rotational torque R2 to be the same, it is possible to maintain the state where R1+R2=RC and RC is constant, as shown in FIG. 4(a). can.

During the period of time s2 to s3, the amount of decrease in the first rotational torque R1 and the amount of increase in the second rotational torque R2 are adjusted based on the temperature difference dT. As a result, as shown in FIG. 4B, the temperature rise of the first temperature T1 is suppressed, and the temperature difference dT is reduced. At time s3, the temperature difference dT becomes smaller than the temperature difference threshold A (dT<A).

At time s3, the temperature difference dT becomes less than the temperature difference threshold A, so the torque distribution mode switches from the temperature difference mode to the normal mode. As a result, as shown in FIG. 4A, the first MG 12 and the second MG 13 are driven with the same rotational torque as in the period of time s0 to s2.

As described above, according to the first embodiment, the ECU 40 controls the first MG 12 that drives the first wheels (wheels 31 and 32) of the vehicle 20 and the second MG 13 that drives the second wheels (wheels 33 and 34). It functions as a drive control device applied to the drive system 10 provided, and includes a temperature acquisition section 41 and a torque distribution section 44 . The temperature acquisition unit 41 acquires the first temperature T1 and the second temperature T2. The torque distributor 44 determines the distribution of the first rotational torque R1 and the second rotational torque R2 in the requested torque RC so that the temperature difference dT between the first temperature T1 and the second temperature T2 is small. Therefore, the torque distribution portion 44 can reduce the temperature difference dT between the MGs 12 and 13 .

The torque distributor 44 selects the high-temperature electric motor and the low-temperature electric motor based on the first temperature T1 and the second temperature T2. For example, the higher temperature first MG 12 is selected as the high temperature motor, and the lower temperature second MG 13 is selected as the low temperature motor. Then, the amount of increase in the second rotational torque R2 of the second MG 13, which is the low-temperature electric motor, is determined according to the amount of reduction in the first rotational torque R1 of the first MG 12, which is the high-temperature electric motor. Therefore, the amount of decrease in the first rotational torque R1 can be compensated for by the amount of increase in the second rotational torque R2.

Furthermore, the torque distribution unit 44 determines distribution of the first rotational torque R1 and the second rotational torque R2 so that the amount of reduction in the first rotational torque R1 and the amount of increase in the second rotational torque R2 are substantially the same. do. Therefore, the amount of decrease in the first rotational torque R1 can be complemented by the amount of increase in the second rotational torque R2, and the required torque RC can be ensured.

(Second embodiment)
FIG. 5 shows a flowchart of drive control processing executed by the ECU 40 according to the second embodiment. The second embodiment is an example of drive control processing when the MGs 12 and 13 perform regenerative operation. The flowchart shown in FIG. 5 differs from the flowchart shown in FIG. 3 in the processes shown in steps S202 to S204. The processes shown in S201, S205, S206, and S208 to S210 shown in FIG. 5 are the same as the processes shown in S101 to S103 and S108 to S110 shown in FIG. 3, respectively. .

In step S201, the required torque RC of the vehicle 20 is calculated. In this case, the required torque RC is calculated as braking torque. After that, the process proceeds to step S202.

In step S202, based on the rotational torque of MGs 12, 13 input from drive shafts 21, 22, the upper limit of input power of inverters 14, 15, and the state of storage battery 11 (SOC, temperature, etc.), MGs 12, 13 A regenerative limit torque RGh, which is a limit value of the sum of the regenerative torques, is calculated. The regeneration limit torque RGh is a value at which the absolute value of the regeneration torque obtained by the MGs 12 and 13 is maximized. The limit value of the regenerative torque of the first MG (the value of R1 when the amount of regenerative torque obtained by the first MG 12 is maximized) is R1h, and the limit value of the regenerative torque of the second MG (the amount of regenerative torque obtained by the second MG 13 is When the value of R2 at the maximum) is R2h, it can be calculated by RGh=R1h+R2h. After that, the process proceeds to step S203.

In step S203, it is determined whether or not the regeneration limit torque RGh exceeds the required torque RC. If RC≧RGh, the process proceeds to step S204 to calculate the braking torque RB to be distributed to the braking devices 35-38. After that, the process proceeds to step S205. If RC<RGh in step S203, the process proceeds directly to step S205.

After step S205, the distribution of the first rotation torque R1 and the second rotation torque R2 in the required torque RC is determined by the same processing as in the first embodiment. When the process of step S204 is performed, the distribution of the first rotational torque R1, the second rotational torque R2, the first braking torque RB1, and the second braking torque RB2 is calculated based on the above equation (1). .

As described above, according to the second embodiment, the ECU 40 sets the first regenerative torque, which is the rotational torque of the first MG 12 during regenerative operation, and the second regenerative torque, which is the rotational torque of the second MG 13 during regenerative operation, to the required torque RC. Second regenerative torque, braking devices 35 and 36 distribute a first braking torque RB1 for braking front wheels 31 and 32, and second braking torque RB2 for braking devices 37 and 38 to brake rear wheels 33 and 34. to decide. By distributing the required torque RC to the braking devices 35 to 38 as well, the temperature load on the MGs 12 and 13 is reduced, so that the temperature rise of the MGs 12 and 13 can be suppressed.

(Third embodiment)
FIG. 6 shows a flowchart of drive control processing executed by the ECU 40 according to the third embodiment. The third embodiment is an example of drive control processing that performs comparison determination between the first temperature T1 and the second temperature T2 and the temperature threshold. The flowchart shown in FIG. 6 differs from the flowchart shown in FIG. 3 in the processes shown in steps S304 to S306. The processes shown in S301 to S303, S309, and S310 shown in FIG. 6 are the same as the processes shown in S101 to S103, S109, and S110 shown in FIG. 3, respectively.

Through steps S301 to S303, the required torque RC is calculated, the first temperature T1 and the second temperature T2 are obtained, and after calculating the temperature difference dT, the process proceeds to step S304. In step S304, similarly to step S108 shown in FIG. 3, it is determined whether the temperature difference dT is the temperature difference threshold A or more. If dT≧A, the process proceeds to step S305. If dT<A, the process proceeds to step S310, where it is determined to perform torque distribution in the normal mode.

In step S305, it is determined whether or not the first temperature T1 is equal to or higher than the first temperature threshold B1. It should be noted that the first temperature threshold B1 is set to a temperature at which the temperature load of the first MG 12 does not pose a problem, taking into account the temperature characteristics of the first MG 12 and deterioration in life. If T1≧B1, the process proceeds to step S306. If T1<B1, the process proceeds to step S310, where it is determined to perform torque distribution in the normal mode.

In step S306, it is determined whether or not the second temperature T2 is equal to or higher than the second temperature threshold B2. Note that the second temperature threshold B2 is set to a temperature at which the temperature load on the second MG 13 does not pose a problem, taking into consideration the temperature characteristics of the second MG 13 and deterioration in life. If T2≧B2, the process proceeds to step S309, where it is determined that torque distribution should be performed in the temperature difference mode. If T2<B2, the process proceeds to step S310, where it is determined to perform torque distribution in the normal mode. Since the cooling rate of the first MG 12 is faster than the cooling rate of the second MG 13, B1>B2 is set.

After step S305, the distribution of the first rotation torque R1 and the second rotation torque R2 in the required torque RC is determined by the same processing as in the first embodiment.

As described above, according to the third embodiment, the ECU 40 determines that the first temperature T1 is equal to or higher than the predetermined first temperature threshold B1 and the second temperature T2 is equal to or higher than the predetermined second temperature threshold B2. As a condition, the distribution with the torque is determined in the temperature difference mode. When the first temperature T1 and the second temperature T2 are sufficiently low and deterioration of the MGs 12 and 13 due to the temperature load is not a problem, the normal mode is selected to distribute the required torque RC with priority given to drivability. be able to.

Further, for the first temperature T1 of the first MG 12 having a high cooling rate, a higher first temperature threshold value B1 is used to make it difficult to select the temperature difference mode, thereby performing torque distribution giving priority to drivability. can. For the second temperature T2 of the second MG 13 having a slow cooling rate, a lower second temperature threshold value B2 is used to facilitate the selection of the temperature difference mode, thereby performing torque distribution that prioritizes reduction of the temperature difference dT. can be done.

(Fourth embodiment)
FIG. 7 shows a flowchart of drive control processing executed by the ECU 40 according to the fourth embodiment. 4th Embodiment is an example of the drive control process which changes the temperature difference threshold value A based on 1st temperature T1 and 2nd temperature T2. The flowchart shown in FIG. 7 differs from the flowchart shown in FIG. 3 in the processes shown in steps S404 to S406. The processing shown in S401 to S403 and S408 to S410 shown in FIG. 7 is the same as the processing shown in S101 to S103 and S108 to S110 shown in FIG. 3, respectively.

Through steps S401 to S403, the required torque RC is calculated, the first temperature T1 and the second temperature T2 are obtained, and after calculating the temperature difference dT, the process proceeds to step S404.

In step S404, it is determined whether or not the first temperature T1 is higher than the second temperature T2. When it is T1>T2, it progresses to step S405 and sets the temperature difference threshold value A to 1st temperature difference threshold value A1 (A=A1). When it is T1<T2, it progresses to step S406 and sets the temperature difference threshold value A to 2nd temperature difference threshold value A2 (A=A2). Since the cooling rate of the first MG 12 is faster than the cooling rate of the second MG 13, A1>A2 is set. After steps S405 and S406, the process proceeds to step S408.

After step S408, the distribution of the first rotation torque R1 and the second rotation torque R2 in the required torque RC is determined by the same processing as in the first embodiment. The temperature difference threshold A used in step S408 is set to the first temperature difference threshold A1 or the second temperature difference threshold A2 in the processing of steps S404 to S406.

As described above, according to the fourth embodiment, the ECU 40 changes the temperature difference threshold value A depending on which of the first temperature T1 and the second temperature T2 is higher. Therefore, the required torque RC can be appropriately distributed according to the case where the temperature characteristics of the first MG 12 and the second MG 13 are different.

Further, when the temperature of the first MG 12 having a high cooling rate becomes higher, a higher first temperature difference threshold value A1 is used to make the temperature difference mode less likely to be selected, thereby performing torque distribution giving priority to drivability. can be done. When the temperature of the second MG 13 with a slow cooling rate becomes higher, a lower second temperature difference threshold value A2 is used to facilitate the selection of the temperature difference mode, thereby performing torque distribution that prioritizes reduction of the temperature difference dT. be able to.

(Fifth embodiment)
FIG. 8 shows a flowchart of drive control processing executed by the ECU 40 according to the fifth embodiment. In the fifth embodiment, whether or not the torque distribution determined by the torque distribution unit 44 is within a torque range required to ensure running stability of the vehicle 20 (hereinafter sometimes referred to as a stable torque range). It is an example of the drive control process including the process of determining whether or not. The flowchart shown in FIG. 8 differs from the flowchart shown in FIG. 3 in the processes shown in steps S511 to S513. The processing shown in S501 to S510 shown in FIG. 8 is the same as the processing shown in S101 to S110 shown in FIG. 3, respectively, so the explanation is omitted by replacing the reference numbers.

In step S509 or S510, the required torque RC is distributed between the first rotation torque R1 and the second rotation torque R2 in the temperature difference mode or the normal mode, and then the process proceeds to step S511.

At step S511, the torque distribution ratio X=R1/R2 is calculated. Further, a lower limit value XL and an upper limit value XH of the torque distribution ratio that define the stable torque range of the vehicle 20 are set. Lower limit value XL and upper limit value XH of the torque distribution ratio are calculated based on the driving condition of vehicle 20, the condition of the travel route, and the like. For example, when climbing a slope, the range of the torque distribution ratio X is set relatively low so that the second rotational torque R2 that drives the rear wheels becomes larger. Conversely, when descending a slope, the range of the torque distribution ratio X is set relatively high so that the first rotational torque R1 that drives the front wheels becomes greater. After step S511, the process proceeds to step S512.

In step S512, it is determined whether or not the torque distribution ratio X calculated in step S511 is within the range of the torque distribution ratio set in step S511. That is, it is determined whether or not XL≦X≦XH is satisfied. If XL≤X≤XH is not satisfied, the process advances to step S513 to recalculate the torque distribution ratio X within the range of the torque distribution ratio set in step S511. That is, the torque distribution ratio X is recalculated within a range that satisfies XL≤X≤XH. If XL≦X≦XH is satisfied, the process ends.

As described above, according to the fifth embodiment, the ECU 40 calculates the torque distribution ratio X between the first rotation torque R1 and the second rotation torque R2, and determines the lower limit of the torque distribution ratio that defines the stable torque range of the vehicle 20. A value XL and an upper limit value XH are calculated. When the torque distribution ratio X calculated by the temperature difference mode or normal mode is not within the torque range (when XL≤X≤XH is not satisfied), the torque is redistributed so as to satisfy the torque range. Run. Therefore, it is possible to perform control to reduce the temperature difference dT between the MGs 12 and 13 within the allowable torque range, giving priority to ensuring the running stability of the vehicle 20 .

According to the above embodiment, the following effects can be obtained.

The ECU 40 functions as a drive control device that drives a drive system of a vehicle driven by a plurality of electric motors (MGs 12, 13), and includes a temperature acquisition unit 41 that acquires the temperatures (T1, T2) of the plurality of electric motors, a torque distribution unit 44 that distributes the required torque RC required for the vehicle 20 to each electric motor so that the temperature difference dT between the plurality of electric motors obtained from the temperatures of the plurality of electric motors obtained by the unit 41 is small; Prepare. Therefore, the torque distribution portion 44 can reduce the temperature difference dT between the MGs 12 and 13 .

According to one embodiment, the torque distribution unit 44 selects the rotational torque from the plurality of electric motors (MG12, 13) based on the temperatures (T1, T2) of the plurality of electric motors obtained by the temperature obtaining unit 41. A high-temperature electric motor to be reduced and a low-temperature electric motor to increase the rotational torque are selected, and the torque distribution unit 44 is configured to determine the amount of increase in the rotational torque of the low-temperature electric motor according to the amount of reduction in the rotational torque of the high-temperature electric motor. It is This configuration can reduce the temperature difference dT between the plurality of electric motors (MG12, 13). Also, the amount of reduction in the rotational torque of the high-temperature electric motor can be compensated for by the amount of increase in the rotational torque of the low-temperature electric motor. Furthermore, the torque distribution unit 44 may be configured to determine the amount of reduction in the rotational torque of the high-temperature electric motor and the amount of increase in the rotational torque of the low-temperature electric motor to be approximately the same. The amount of reduction in the rotational torque of the high-temperature electric motor can be complemented by the amount of increase in the rotational torque of the low-temperature electric motor, and the required torque RC can be ensured.

The drive system 10 includes braking devices 35 to 38 for braking wheels 31 to 34 of the vehicle 20, and includes generator motors MG12 and MG13 as a plurality of electric motors. In this case, the torque distribution unit 44 may be configured to distribute the requested torque RC to the MGs 12, 13 and the braking devices 35-38. By distributing the required torque RC also to the braking devices 35 to 38, the load on the generator motors (MG12, 13) is reduced, so that the temperature rise of the generator motors (MG12, 13) can be suppressed.

According to one embodiment, the torque distribution unit 44 sets the temperature difference dT between the electric motors (MG12, 13) obtained from the temperatures of the plurality of electric motors (MG12, 13) acquired by the temperature acquisition unit 41 to a predetermined temperature. Provided that the temperature difference dT is equal to or greater than the difference threshold value A, the required torque RC is distributed to the respective electric motors (MG12, 13) so that the temperature difference dT becomes small. When the temperature difference dT is so small that it does not exceed the temperature difference threshold A, and uneven deterioration of the motors (MGs 12, 13) does not pose a problem, the normal mode is selected, and priority is given to drivability. Torque RC can be distributed. Furthermore, the torque distribution unit 44 may be configured to change the temperature difference threshold A according to which of the plurality of electric motors (MG12, 13) has the highest temperature. The required torque RC can be appropriately distributed according to the case where the temperature characteristics of the plurality of electric motors (MG12, 13) are different.

According to one embodiment, the torque distribution unit 44 determines the temperature of the plurality of electric motors (MG12, 13) obtained by the temperature obtaining unit 41 on the condition that the temperatures are equal to or higher than predetermined temperature thresholds (B1, B2). The required torque RC is applied to each of the electric motors (MG12, 13) so that the temperature difference dT between the electric motors (MG12, 13) obtained from the temperatures of the plurality of electric motors (MG12, 13) obtained by the obtaining unit 41 is small. configured to distribute. When the temperature of each electric motor (MG12, 13) is sufficiently low and deterioration due to temperature load is not a problem, the normal mode is selected, and the required torque RC can be distributed with priority given to drivability. Furthermore, the torque distribution unit 44 may be configured to change the temperature difference threshold A according to which of the plurality of electric motors (MG12, 13) has the highest temperature. The required torque RC can be appropriately distributed according to the temperature characteristics of each electric motor (MG12, 13).

According to one embodiment, the torque distribution unit 44 sets a torque range (stable torque range) required to ensure running stability of the vehicle 20 for each of the plurality of electric motors (MGs 12, 13). , the required torque RC is distributed to the respective electric motors (MG12, 13) within the stable torque range of the respective electric motors (MG12, 13). Prioritizing ensuring the running stability of the vehicle 20, control can be executed to reduce the temperature difference dT between the plurality of electric motors (MGs 12, 13) within the stable torque range.

The drive system 10 includes temperature sensors 53 and 54 that detect temperatures of the plurality of electric motors (MG12 and 13), and the ECU 40 obtains predicted temperatures of the plurality of electric motors (MG12 and 13) after a predetermined time has elapsed. A temperature prediction unit 42 for prediction is provided. In this case, the temperature acquisition unit 41 acquires the detected values of the temperature sensors 53 and 54 and the predicted values predicted by the temperature prediction unit 42 as the temperatures (T1, T2) of the plurality of electric motors (MGs 12, 13). It may be configured to be possible. Further, in the temperature difference mode, the torque distribution unit 44 calculates the required torque based on the temperature difference dT calculated using one or both of the detected temperature values and the predicted temperature values of the plurality of electric motors (MG 12, 13). It may be configured to distribute the RC to each motor. Since the temperature detection values and predicted values of the plurality of electric motors (MG12, 13) can be appropriately used, the temperature difference between the electric motors (MG12, 13) can be reduced more reliably.

(Other embodiments)
- In the above-described embodiment, the vehicle 20 provided with the two generator motors (MG12, 13) was described as an example, but the present invention is not limited to this. The technical concept described in each of the above embodiments can also be applied to a vehicle drive system having three or more electric motors or generator motors, and the temperature difference between each motor or generator motor described in each of the above embodiments can be applied. can be configured to obtain an effect such as reducing the

In addition to the generator motor, the technical concept described in each of the above embodiments can also be applied to a vehicle drive system having an internal combustion engine as a torque generation source. It can be configured to obtain an effect such as reducing the temperature difference of the generator-motor.

- Although the case where one ECU40 controls each structure of the drive system 10 was illustrated and demonstrated above, it is not limited to this. A main ECU including a temperature acquisition unit 41, a temperature prediction unit 42, a torque calculation unit 43, a torque distribution unit 44, and a control command unit 45 similar to the ECU 40; You may provide separately with ECU which controls each structure, respectively. In this case, the main ECU may be configured to transmit a control command signal to an ECU that controls each component of the drive system 10 to control each component.

DESCRIPTION OF SYMBOLS 10... Drive system, 12... 1st MG, 13... 2nd MG, 20... Vehicle, 40... ECU, 41... Temperature acquisition part, 44... Torque distribution part

Claims (9)

A drive control device (40) for driving a drive system (10) of a vehicle (20) driven by a plurality of electric motors (12, 13),
a temperature acquisition unit (41) for acquiring temperatures of the plurality of electric motors;
A torque distribution unit (44) for distributing the required torque required for the vehicle to each of the electric motors so that the temperature difference between the plurality of electric motors based on the temperatures of the plurality of electric motors obtained by the temperature obtaining unit is reduced. ) and
The torque distribution unit acquires the distributing the required torque to each of the electric motors so that the temperature difference between the plurality of electric motors is small;
The torque distribution unit changes the temperature difference threshold according to which one of the plurality of electric motors has the highest temperature,
The drive control device , wherein the temperature difference threshold is changed so as to be higher as the cooling rate of the electric motor having the highest temperature is faster . The torque distribution unit selects a high-temperature electric motor for reducing rotational torque and a low-temperature electric motor for increasing rotational torque from among the plurality of electric motors based on the temperatures of the plurality of electric motors obtained by the temperature obtaining unit. select,
2. The drive control device according to claim 1, wherein the amount of increase in rotational torque of said low-temperature electric motor is determined according to the amount of reduction in rotational torque of said high-temperature electric motor. 3. The drive control device according to claim 2, wherein the torque distribution unit determines the reduction amount of the rotational torque of the high-temperature electric motor and the amount of increase of the rotational torque of the low-temperature electric motor to be substantially the same. The drive system comprises a braking device (35-38) for braking the wheels (31-34) of the vehicle,
The plurality of electric motors are generator motors capable of power running operation for driving the wheels and regenerative operation for generating power using rotational energy of the wheels,
The drive control device according to any one of claims 1 to 3, wherein the torque distribution section distributes the requested torque to the generator motor and the braking device. The torque distribution unit performs the torque distribution based on the temperatures of the plurality of electric motors obtained by the temperature obtaining unit on condition that the temperatures of the plurality of electric motors obtained by the temperature obtaining unit are equal to or higher than a predetermined temperature threshold. The drive control device according to any one of claims 1 to 4 , wherein the required torque is distributed to each of the electric motors so that the temperature difference between the electric motors becomes small. 6. The drive control device according to claim 5 , wherein the torque distribution unit changes the temperature threshold according to which one of the plurality of electric motors has the highest temperature. A drive control device (40) for driving a drive system (10) of a vehicle (20) driven by a plurality of electric motors (12, 13),
a temperature acquisition unit (41) for acquiring temperatures of the plurality of electric motors;
A torque distribution unit (44) for distributing the required torque required for the vehicle to each of the electric motors so that the temperature difference between the plurality of electric motors based on the temperatures of the plurality of electric motors obtained by the temperature obtaining unit is reduced. ) and
The torque distribution unit performs the torque distribution based on the temperatures of the plurality of electric motors obtained by the temperature obtaining unit, on condition that the temperatures of the plurality of electric motors obtained by the temperature obtaining unit are equal to or higher than a predetermined temperature threshold. Distributing the required torque to each of the electric motors so that the temperature difference between the plurality of electric motors is small;
The torque distribution unit changes the temperature threshold according to which one of the plurality of electric motors has the highest temperature,
The drive control device , wherein the temperature threshold is changed so as to be higher as the cooling speed of the electric motor having the highest temperature is faster . The torque distribution unit sets a torque range required for ensuring running stability of the vehicle for each of the plurality of electric motors, and the torque distribution unit sets torque ranges within the torque ranges set for each of the plurality of electric motors. The drive control device according to any one of claims 1 to 7 , wherein the required torque is distributed to each of the electric motors. The drive system includes temperature sensors (53, 54) that detect temperatures of the plurality of electric motors,
The drive control device includes a temperature prediction unit (42) that predicts predicted values of temperatures of the plurality of electric motors after a predetermined time has elapsed,
The temperature acquisition unit is capable of acquiring, as temperatures of the plurality of electric motors, values detected by the temperature sensor and values predicted by the temperature prediction unit,
Based on at least one of the detected value and the predicted value obtained by the temperature obtaining unit, the torque distributing unit adjusts the requested torque so as to reduce the temperature difference between the plurality of electric motors. The drive control device according to any one of claims 1 to 8 , which is distributed to each electric motor.

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