JP2007325372A - Electric vehicle controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric vehicle controller capable of maintaining vehicle behavior, even if battery residual capacity is decreased and output limit is applied to a motor during torque distribution control using output torque of the motor. <P>SOLUTION: The electric vehicle controller includes an upper limit battery output setting means for setting an upper battery output according to the state of charge of a battery 301 in an electric vehicle provided with a torque distribution control means for controlling the front and rear wheel torque distribution using the output torque of a first motor 301 and a second motor 308, and a yaw rate sensor 407 for detecting a yaw rate. The torque distribution control means applies the output limit to a second motor 308 earlier than a first motor 301 so as to hold the yaw rate, if the total output of the first motor 301 and the second motor 308 exceeds the upper battery output during the torque distribution control. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a control apparatus for an electric vehicle that has a plurality of motors as a driving force source and controls at least one of front and rear wheel torque distribution and left and right wheel torque distribution using output torque of the motor.

(Prior art 1)
Conventionally, an engine, a first motor that is mechanically coupled to the engine and the front wheels and electrically coupled to the battery, and mechanically coupled to the rear wheels and electrically coupled to the battery An electric four-wheel drive vehicle including a second motor is known (for example, see Patent Document 1).

(Prior art 2)
On the other hand, a mechanical four-wheel drive vehicle that realizes a neutral steer by controlling the front-rear distribution at 30:70 to 70:30 and the rear-wheel left-right distribution at 100: 0 to 0: 100 in a stepless manner is known (for example, Patent Document 2).
JP 2004-222413 A JP 2004-189067 A

However, when the technical concept of the driving force distribution of the prior art 2 is applied to the electric four-wheel drive vehicle of the prior art 1, the following problems occur.
In other words, the first motor and the second motor are driven so as to realize neutral steering, but there is a single driving battery mounted on the vehicle, and the input / output limit values set based on the battery characteristics are the same for both motors. Will be applied in common. In other words, when the remaining battery capacity decreases, both the first motor and the second motor are limited in output. For example, in the case of an electric four-wheel drive vehicle based on a front wheel drive, the front and rear wheels necessary for realizing the neutral steer There was a problem that the ratio of driving force distribution collapsed and the behavior of the vehicle tends to oversteer.

  The present invention has been made paying attention to the above problem, and can maintain the vehicle behavior even when the remaining battery capacity is reduced and the motor is limited in output during torque distribution control using the output torque of the motor. An object of the present invention is to provide a control device for an electric vehicle.

  In order to solve the above problems, a control device for an electric four-wheel drive vehicle according to the present invention includes a plurality of electric motors as drive sources, a battery that supplies electric power to the plurality of electric motors, and an output torque of the plurality of motors. In an electric vehicle comprising: torque distribution control means for controlling at least one of front and rear wheel torque distribution and left and right wheel torque distribution using, and a yaw rate detection means for detecting the yaw rate; an upper limit according to the state of charge of the battery An upper limit battery output setting means for setting a battery output is provided, and the torque distribution control means is detected by the yaw rate detection means when a total output of the plurality of motors exceeds the upper limit battery output during the torque distribution control. The output restriction is applied to the plurality of electric motors so as to maintain the yaw rate.

  In the control apparatus for an electric vehicle according to the present invention, when the total output of the plurality of motors exceeds the upper limit battery output, output restriction is applied to the plurality of motors so as to maintain the yaw rate. In other words, when the total output of multiple motors exceeds the upper limit battery output, the output limits are applied to the multiple motors to maintain the yaw rate before the output limit is exceeded, rather than uniformly limiting the output to the multiple motors. . Therefore, in a front wheel drive-based vehicle, even if output restriction is applied during turning, it is possible to prevent an oversteer tendency and to ensure traveling stability.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the best mode for carrying out an electric vehicle control apparatus of the present invention will be described based on Examples 1 to 3 shown in the drawings.
Embodiments of the present invention will be described with reference to the drawings.

First, the configuration will be described.
FIG. 1 is an overall configuration diagram of an electric vehicle control apparatus according to a first embodiment of the present invention.
As shown in FIG. 1, the electric vehicle according to the first embodiment includes a CPU 101, an auxiliary battery 102, a high-power battery 301 (battery), an FR inverter 302, a first motor 303 (first electric motor), and a generator. 304, engine 305, power split mechanism 306, RR inverter 307, second motor 308 (second electric motor), differential mechanism 311 (left and right wheel driving force distribution mechanism), accelerator sensor 401, brake sensor 402, a DC / DC converter 403, a steering angle sensor 404, a wheel speed sensor 406, a yaw rate sensor 407, and a warning lamp 408.

  The CPU 101 monitors the high-power battery 301, calculates the input / output possible electric energy according to the SOC, temperature, and deterioration state, and controls the FR inverter 302 based on the calculated input / output power amount, thereby the first motor 303 (front drive). And the generator 304 are operated, and the engine 305 is controlled. Further, by controlling the RR inverter 307, the second motor 308 (for rear driving) is operated, and further, the steering to the right and left wheels is instructed to the differential mechanism 311 to realize neutral steering. Driving force distribution control for front and rear wheels and driving force distribution control for left and right rear wheels are performed. Further, based on the detection value from the rudder angle sensor 404, it is determined whether or not the vehicle is turning. Further, the CPU 101 confirms the detection value from the wheel speed sensor 406 and grasps each wheel speed. Then, the detected value from the yaw rate sensor 407 is confirmed to grasp the behavior of the electric vehicle, that is, the yaw moment.

  The auxiliary battery 102 serves to provide an operating power source for the CPU 101. In this system, power is supplied by a DC / DC converter 403 that uses a high-power battery 301 as a power source.

  The high-power battery 301 assists vehicle travel by supplying electric power to the first motor 303 via the FR inverter 302, and uses the electric power generated by the generator 304 via the RR inverter 307. Has the role of collecting. In addition, when the second motor 308 is powered, the vehicle travel is assisted by supplying power via the RR inverter 307, and when the second motor 308 generates power, the power is supplied via the RR inverter 307. It also has the role of collecting power.

  The FR inverter 302 is directly controlled by the CPU 101. The electric energy of the high-power battery 301 is supplied to the first motor 303 according to the generated torque and the rotational speed of the engine 305, and the electric energy generated by operating the generator 304 is returned to the high-power battery 301. Since the first motor 303, the generator 304, and the engine 305 are directly connected to the planetary gear mechanism (built in the power split mechanism 306), the vehicle is normally operated unless controlled so as to maintain a balance between torque and rotational speed. It cannot be activated.

  The first motor 303 is for front drive and generates drive torque independently when the vehicle speed is low. Further, when the vehicle speed is high, the driving torque of the engine 305 is assisted. Further, during deceleration, it has a function of generating electric energy by generating power (regenerative action) and returning it to the high voltage battery 301 via the FR inverter 302. Further, the control is applied with the motor rotation speed = vehicle speed.

  The generator 304 basically has no starter in a hybrid electric vehicle. At the time of starting the vehicle to which this system is applied, the electric power is supplied from the high-power battery 301 and the engine 305 is started by operating as a motor. During normal travel, electric energy is generated (power generation) by balancing the first motor 303 and the engine 305 and returned to the high-power battery 301. Sometimes, it is possible to cope with rapid acceleration by supplying the first motor 303 directly.

  The engine 305 is directly controlled by the CPU 101. Specifically, when the vehicle speed is high, torque is generated to drive the vehicle.

  The power split mechanism 306 has a planetary gear mechanism, and an engine 305 is directly connected to the carrier, a first motor 303 is connected to the ring gear, and a generator 304 is directly connected to the sun gear. The transmission equivalent of the conventional system is also configured inside.

  The RR inverter 307 is directly controlled by the CPU 101. It has a role of supplying / recovering the electric energy of the high-power battery 301 according to the generated torque and the rotational speed of the second motor 308. In addition, a temperature sensor is incorporated so that power input / output restriction (component protection) can be performed when the temperature rises, and the detected value is transmitted to the CPU 101.

  The second motor 308 is for rear drive, and is responsible for the function as a 4WD vehicle during normal driving, and during turning, torque is generated due to the increase in the driving course caused by the inner wheel difference, and driving / steering stability. Contributes to improvement.

  The differential mechanism 311 has a function of distributing the torque generated by the second motor 308 to the left and right wheels. Specifically, in addition to a normal differential mechanism, a speed increasing mechanism, a right clutch, and a left clutch are provided in addition to a normal differential mechanism, and these are controlled in accordance with a command from the CPU 101.

  The accelerator sensor 401 transmits to the CPU 101 the accelerator pedal stroke amount that the driver has depressed during acceleration.

The brake sensor 402 transmits to the CPU 101 the brake pedal stroke amount that the driver has depressed during deceleration.

  The DC / DC converter 403 converts the energy from the high voltage battery 301 into 12V and supplies it to the auxiliary battery 102. That is, it has the same function as an alternator in a conventional engine vehicle.

  The rudder angle sensor 404 has a function of transmitting a rudder angle detected by a driver's steering operation to the CPU 101.

  The wheel speed sensor 406 detects speed information of each wheel, and transmits the detected value to the CPU 101 as wheel speed information.

  The yaw rate sensor 407 detects the own vehicle behavior, that is, the yaw moment, and transmits the detected value to the CPU 101.

  The warning light 408 is used to announce to the driver whether or not the control of the present invention, that is, the control when the motor output is limited, is controlled by the CPU 101.

Next, the operation will be described.
FIG. 2 is a flowchart showing the flow of the driving force distribution control process executed by the CPU 101 of the first embodiment. Each step will be described below (driving force distribution control means).

In Step S1, it is determined whether or not the vehicle is turning. If Yes, the process proceeds to Step S2. If No, the process returns to Step S1.
Here, “determination during turning of the vehicle” determines that the vehicle is turning when the detected value (absolute value) from the rudder angle sensor 404 is equal to or greater than a specified value.

In step S2, following the determination that the vehicle is turning in step S1, the necessary torque distribution for the four wheels is determined by the vehicle speed V recognized from the rotation speed of the first motor 303 and the turning radius R recognized from the rudder angle sensor 404. Is set, and the process proceeds to step S3.
Here, the “front and rear wheel torque distribution” is, for example, a distribution in which the rear wheel torque is increased as the turning radius R is smaller and the vehicle speed V is higher, and the “rear wheel left and right torque distribution” is an inner wheel difference during turning. It incorporates the characteristics that the higher the vehicle speed V, the smaller the steering angle, and the larger the steering angle. The smaller the turning radius R (= the larger the steering angle) and the higher the vehicle speed V, the greater the torque distribution to the turning outer wheel side. .

  In step S3, following the setting of the four-wheel torque distribution in step S2, in order to confirm the presence or absence of the SOC of the high-power battery 301 that can generate the set torque, the SOC (State Of Charge: charge capacity) or battery of the high-power battery 301 is checked. The temperature (battery temperature) is confirmed, and the process proceeds to step S4.

In step S4, following the battery SOC monitor in step S3, it is determined whether or not driving force distribution control can be realized. If Yes, the process proceeds to step S5, and if No, the process proceeds to step S6.
Here, the “determination of whether or not the driving force distribution control is feasible” sets the upper limit battery output (upper limit battery output setting means) based on the SOC and temperature of the high-power battery 301, and is necessary for the four-wheel torque distribution. When the total output of the first motor 303 and the second motor 308 is less than or equal to the upper limit battery output, it is determined that the driving force distribution control can be realized, and when the total output of the first motor 303 and the second motor 308 exceeds the upper limit battery output It is determined that driving force distribution control cannot be realized.

In step S5, following the determination that the driving force distribution control can be realized in step S4, a control command for obtaining the distribution torque to the four wheels set in step S4 is output, and the process proceeds to return.
Here, the “distributed torque command to the four wheels” is a control command that is output to the FR inverter 302 and the RR inverter 307 to set the front and rear wheel distributed torque, and the rear wheel left and right distributed torque The setting is performed by outputting a control command to the differential mechanism 311.

  In step S6, following the determination that the driving force distribution control cannot be realized in step S4, the yaw rate is confirmed. Further, it is determined which wheel is the outer wheel by confirming the yaw rate.

  In step S7, the output limit value of the motor is set by referring to the map of FIG. 8 based on the SOC and temperature of the high-power battery 301 and the detected values of the vehicle speed and yaw rate.

In step S8, first, output restriction to the first motor 303 is started. Subsequently, in step S9, output restriction to the second motor is started, and a return is made.
Here, when the output restriction is applied to the first motor and the second motor, the output restriction is applied to each motor based on the torque reduction speed setting map shown in FIGS. 6 and 7. In FIG. 6, the torque reduction speed is set smaller as the vehicle speed and the required torque are larger. This is because the influence on the vehicle behavior with respect to the yaw rate change is increased when the vehicle speed is high. In FIG. 7, the torque reduction speed is increased as the yaw rate change amount is larger. This is because the influence on the vehicle behavior is increased when the yaw rate change amount is large. FIG. 8 is a map for setting the output restriction rate in consideration of the yaw rate and the vehicle speed. Considering the fact that the higher the vehicle speed, the higher the power consumption, and the higher the yaw rate, the larger the rear outer wheel output and the higher the power consumption. ing. The output limit rate of the motor is calculated by multiplying the limit rate set by the SOC and temperature of the high-power battery 301 by the output limit rate set with reference to the map of FIG.

Next, the change characteristics of the required torque of the first motor and the second motor will be described based on the time chart shown in FIG.
As shown in FIG. 9, the required torques of the first motor and the second motor in the normal time when the motor output is not limited are gradually increased as the degree of turning increases to achieve neutral steering during turning. The required torque for the second motor gradually increases. That is, as the front / rear wheel driving force distribution ratio, the torque distribution to the rear wheel side is increased as the degree of turning increases from the distribution ratio in which a large amount of torque is distributed to the front wheel side, thereby alleviating the understeer tendency.
The rear wheel left / right torque ratio is such that when the vehicle is turning left, the torque distribution to the left rear wheel gradually decreases and the torque distribution to the right rear wheel, which is the outer turning wheel, gradually increases. For this reason, as for the steer characteristics, if the torque distributed to the left and right rear wheels enters the corner with equal distribution, there will be no oversteer moment, but the torque applied to the turning outer wheel after entering the corner By increasing the distribution, an oversteer moment is generated, weak understeer characteristics are relaxed, and neutral steer is realized. When the vehicle is turning in a state where the output is not limited as described above, the driving force distribution control of the front and rear wheels and the left and right rear wheels by the output control of the first motor and the second motor and the distribution ratio control of the differential mechanism 311 is executed. A highly stable neutral steer can be realized.

As shown in FIG. 9, the change characteristics of the required torque of the first motor and the second motor when the SOC is low, that is, when the output restriction is applied, are as follows. Decrease. Then, following the output limitation of the second motor, the required torque of the first motor gradually decreases. The front-rear total torque at this time decreases by the amount that the output to the first motor and the second motor is limited. The total torque ratio in the front and rear is also different from the normal time, but in the present invention, the output is not limited to the first motor and the second motor at the same time, but the output is first limited to the second motor, and thereafter Output restriction is applied to the first motor.
For this reason, as the steer characteristic, a steer tendency is exhibited when the same output restriction amount is applied to the first motor and the second motor at the same time, but in the present invention, the second motor is first presented. By limiting the output to the lower limit, the steer characteristic tends to be weakly under, and after that, the output is limited to the first motor so that the steer characteristic tends to be weakly over, so the yaw rate before and after applying the output limit is maintained. I am doing so.

Next, the effect will be described.
In the control apparatus for an electric vehicle according to the first embodiment, the following effects can be obtained.

  Front and rear wheels using the first motor 301 and the second motor 308 as drive sources, the battery 301 for supplying power to the first motor 301 and the second motor 308, and the output torque of the first motor 301 and the second motor 308 In an electric vehicle including a torque distribution control unit that controls torque distribution and a yaw rate sensor 407 that detects a yaw rate, an upper limit battery output setting unit that sets an upper limit battery output according to the state of charge of the battery 301 is provided. The torque distribution control means is configured to maintain the yaw rate detected by the yaw rate sensor 407 when the total output of the first motor 301 and the second motor 308 exceeds the upper limit battery output during the torque distribution control. By applying an output restriction to the second motor 308 before 301, the output restriction is made when turning. Vignetting can also be ensured running stability.

  Further, the torque reduction speed when the output of each of the first motor 301 and the second motor 308 is limited is decreased as the vehicle speed or the required torque increases using the map shown in FIG. 6, and the torque shown in FIG. Since the torque reduction speed is set to increase as the yaw rate change amount increases using the reduction speed setting map, it is possible to suppress the uncomfortable feeling of the vehicle behavior change for the vehicle occupant when the output is limited.

  The second embodiment is an example in which the left and right rear wheels are subjected to torque distribution control of the left and right rear wheels by two motors.

First, the configuration will be described. FIG. 3 is a system configuration diagram to which the control device for the electric vehicle according to the third embodiment is applied.
As shown in FIG. 7, the CPU 101, the auxiliary battery 102, the high voltage battery 301, the FR inverter 302, the first motor 303 (first electric motor), the generator 304, the engine 305, and the power split mechanism 306. RR inverter 307, second motor 308 (second motor), third motor 309, accelerator sensor 401, brake sensor 402, DC / DC converter 403, rudder angle sensor 404, wheel speed A sensor 406, a yaw rate sensor 407, and a warning lamp 408 are provided. The second motor 308 and the third motor 309 that drive the left and right rear wheels independently form a left and right wheel driving force distribution mechanism. The description of the configuration having the same function as the configuration of the first embodiment shown in FIG. 1 is omitted.

  The CPU 101 controls the RR inverter 307 to operate the second motor 308 (for the right rear drive) and the third motor 309 (for the left rear drive) to drive the left and right rear wheels that achieve neutral steering. Perform distribution control.

  When the second battery 308 and the third motor 309 are powered, the high-power battery 301 assists vehicle travel by supplying power via the RR inverter 307, and the second motor 308 and the third motor 309. Has a role of recovering electric power via the RR inverter 307.

  The second motor 308 is in charge of right rear driving as a 4WD vehicle during normal travel, and generates torque in the travel course increase caused by the inner wheel difference during turning travel, thereby contributing to improved travel and steering stability.

  The third motor 309 is in charge of left rear drive as a 4WD vehicle during normal travel, and generates torque in the travel course increase caused by the inner wheel difference during turning travel, thereby contributing to improved travel and steering stability.

  Regarding the operation, in the first embodiment, the torque limiting control is performed by the first motor 303 and the second motor 308, and the optimization control of the driving force distribution to the left and right rear wheels is performed by the differential mechanism 311. 2 is different in that the torque limiting control and the optimization control of the driving force distribution to the left and right rear wheels are performed by the first motor 303, the second motor 308, and the third motor 308.

  FIG. 8 is a flowchart executed by the CPU 101 according to the second embodiment. Steps different from the first embodiment will be described.

  In the second embodiment, the “distributed torque command to four wheels” in step S5 is performed by outputting a control command to the RR inverter 307 in response to the setting of the rear wheel left / right distributed torque.

  In step S6, the outer ring is determined in the yaw rate confirmation. Here, it is assumed that the second motor 308 drives the rear outer ring.

  In step S7, output limit values of the first motor 303, the second motor 308, and the third motor 309 are set.

  In step S8, first, output limitation of the second motor 308 is started. Subsequently, in step S9, output restriction to the first motor is started, and in step S10, output restriction of the third motor 309 is started, and the process proceeds to return. Here, when the output is limited to the first motor, the second motor, and the third motor, the output limit value and the torque reduction speed are set based on the maps of FIGS. 3, 4, and 5 as in the first embodiment. Is done.

Next, the required torque change characteristics of the first motor, the second motor, and the third motor will be described based on the time chart shown in FIG.
As shown in FIG. 9, the required torques of the first motor, the second motor, and the third motor in a normal time when the motor output is not limited are during turning, and the rear wheel left-right torque ratio is when the vehicle is turning left, The required torque for the second motor increases and the required torque for the third motor decreases. For this reason, as for the steer characteristics, if the torque distributed to the left and right rear wheels enters the corner with equal distribution, there will be no oversteer moment, but the torque applied to the turning outer wheel after entering the corner By increasing the distribution, an oversteer moment is generated, weak understeer characteristics are relaxed, and neutral steer is realized. When turning in a state where there is no output restriction in this way, neutral steering with high running stability is realized by executing driving force distribution control of the front and rear wheels and left and right rear wheels by output control of the second motor and third motor it can.

As shown in FIG. 9, the change characteristics of the required torques of the first motor, the second motor, and the third motor when the SOC is low, that is, when the output is restricted, are as follows. Torque gradually decreases. Then, following the output limitation of the second motor, the required torque of the first motor gradually decreases. Finally, the required torque of the third motor decreases. The front-rear total torque at this time decreases by the amount that limits the output to the first motor, the second motor, and the third motor. The front and rear total torque ratio and the left and right rear wheel torque ratios are also different from the normal time, but in the second embodiment of the present invention, the output restriction is not applied simultaneously to the first motor, the second motor and the third motor. First, output restriction is applied to the second motor, then output restriction is applied to the first motor, and finally output restriction is applied to the third motor.
For this reason, as a steer characteristic, when an output limit is applied to the first motor, the second motor, and the third motor at the same time with the same output limit amount, an oversteer tendency is exhibited. By first limiting the output to the second motor, the steer characteristic tends to be weakly under, and then by limiting the output to the first motor, the steer characteristic tends to be weakly over, and finally the output is limited to the third motor. It is over. In other words, the yaw rate before and after the output restriction is maintained by appropriately shifting the timing for applying the output restriction, thereby suppressing the oversteer tendency.

Next, the effect will be described.
In the control apparatus for an electric vehicle according to the second embodiment, the following effects can be obtained.
A first motor 303 for driving the front wheel, a second motor 308 for driving the right wheel of the rear wheel, a third motor 309 for driving the left wheel of the rear wheel, the first motor 303, the second motor 308, and the The battery 301 that supplies power to the third motor 309, and the output torque of the motor on the outer ring side of the second motor 308 and the third motor 309 during turning of the vehicle is larger than the output torque of the motor on the inner ring side. In an electric vehicle provided with torque distribution control means for executing left and right wheel torque distribution control,
Upper limit battery output setting means for setting an upper limit battery output according to the state of charge of the battery 301 is provided, and the torque distribution control means is configured to perform the first motor 303, the second motor 308, and the third motor during the torque distribution control. When the total output of the motor 309 exceeds the upper limit battery output, during the left turn, the second motor 308, the first motor 303, and the third motor 309 are subjected to output restriction in this order to turn. Even if the output is restricted, the tendency to oversteer can be suppressed, and traveling stability can be ensured.

  The third embodiment is an example in which a motor is individually installed on the left and right front wheels with respect to the second embodiment, and a motor is installed on each wheel.

First, the configuration will be described. FIG. 10 is a system configuration diagram to which the control device for the electric vehicle according to the third embodiment is applied.
As shown in FIG. 10, CPU 101, auxiliary battery 102, high-power battery 301, FR inverter 302, first motor 303 (first motor), second motor 308 (second motor), and RR An inverter 307, a third motor 309 (third motor), a fourth motor 310, an accelerator sensor 401, a brake sensor 402, a DC / DC converter 403, a steering angle sensor 404, a wheel speed sensor 406, A yaw rate sensor 407 and a warning lamp 408 are provided. The third motor 309 and the fourth motor 310 that drive the left and right rear wheels independently form a left and right wheel driving force distribution mechanism. The description of the configuration having the same function as the configuration of the first embodiment shown in FIG. 1 is omitted.

  The CPU 101 controls the RR inverter 307 to operate the third motor 309 (for the right rear drive) and the fourth motor 310 (for the left rear drive) to drive the left and right rear wheels that achieve neutral steering. Perform distribution control.

  When the third battery 308 and the fourth motor 310 are powered, the high-power battery 301 assists vehicle travel by supplying electric power via the RR inverter 307, and the third motor 309 and the fourth motor 310. Has a role of recovering electric power via the RR inverter 307.

  The first motor 303 and the second motor 308 are main driving force sources of the electric vehicle according to the present embodiment.

  The third motor 309 is in charge of right rear driving as a 4WD vehicle during normal traveling, and generates torque in the travel course increase caused by the inner wheel difference during turning travel, thereby contributing to improved traveling and steering stability.

  The fourth motor 310 is in charge of driving the left rear as a 4WD vehicle during normal travel, and generates torque in the travel course increase caused by the inner wheel difference during turning travel, thereby contributing to improved travel and steering stability.

  Regarding the operation, the front wheels are driven by the engine and the first motor 303 in the first and second embodiments, whereas the third embodiment is driven by the first motor 303 and the second motor 308.

  FIG. 11 is a flowchart executed by the CPU 101 according to the third embodiment. Steps different from the second embodiment will be described.

  In step S6, the outer ring is determined in the yaw rate confirmation. Here, it is assumed that the third motor 309 drives the rear outer ring.

  In step S7, output limit values of the first motor 303, the second motor 308, the third motor 309, and the fourth motor 310 are set.

  In step S8, first, output limitation of the third motor 309 is started. Subsequently, in step S9, output restriction to the first motor 303 and the second motor 308 is started, and finally, output restriction of the fourth motor 310 is started in step S10, and the process proceeds to return. Here, when the output restriction is applied to the first motor, the second motor, the third motor, and the fourth motor, the output restriction value and the torque reduction speed are the same as those in the first embodiment shown in FIGS. Set based on map.

Next, the change characteristics of the required torque of the first motor, the second motor, the third motor, and the fourth motor will be described based on the time chart shown in FIG.
As shown in FIG. 12, the required torques of the first motor, the second motor, the third motor, and the fourth motor at the normal time when the motor output is not limited are increased as the degree of turning increases in order to achieve neutral steer during turning. As for the rear wheel left / right torque ratio, the required torque of the third motor increases and the required torque of the fourth motor decreases when the vehicle is turning left. For this reason, as for the steer characteristics, if the torque distributed to the left and right rear wheels enters the corner with equal distribution, there will be no oversteer moment, but the torque applied to the turning outer wheel after entering the corner By increasing the distribution, an oversteer moment is generated, weak understeer characteristics are relaxed, and neutral steer is realized. As described above, when turning with no output restriction, neutral steering with high running stability can be realized by executing the driving force distribution control of the left and right rear wheels by the output control of the third motor and the fourth motor.

As shown in FIG. 9, the change characteristics of the required torques of the first motor, the second motor, the third motor, and the fourth motor when the SOC is low, that is, when the output is restricted, are as follows. The required torque of 3 motors gradually decreases. Then, following the output limitation of the third motor, the required torques of the first motor and the second motor gradually decrease. Finally, the required torque of the fourth motor decreases. The front-rear total torque at this time decreases by the amount that the output to the first motor, the second motor, the third motor, and the fourth motor is limited. In addition, although the front-rear total torque ratio and the left and right rear wheel torque ratios are also different from the normal time, in the third embodiment of the present invention, output restriction is simultaneously applied to the first motor, the second motor, the third motor, and the fourth motor. Instead, the output restriction is first applied to the third motor, the output restriction is applied to the first motor and the second motor, and the output restriction is applied to the fourth motor.
For this reason, as the steer characteristic, when the output limit is applied to the first motor, the second motor, the third motor, and the fourth motor at the same time with the same output limit amount, an oversteer tendency is exhibited. In the present invention, the steer characteristic tends to be weakly under by applying the output limit to the third motor first, and the steer characteristic is set to be weakly over by applying the output limit to the first motor and the second motor after that. Finally, output restriction is applied to the fourth motor. In other words, the yaw rate before and after the output restriction is maintained by appropriately shifting the timing for applying the output restriction, thereby suppressing the oversteer tendency.

Next, the effect will be described.
In the control device for an electric vehicle according to the third embodiment, the following effects can be obtained.
A first motor 303 that drives the right wheel of the front wheel, a second motor 308 that drives the left wheel of the front wheel, a third motor 309 that drives the right wheel of the rear wheel, and a fourth motor that drives the left wheel of the rear wheel A motor 310, a first motor 303, a second motor 308, a third motor 309, a battery 301 for supplying power to the fourth motor 310, and the third motor 309 and the fourth motor during vehicle turning. 310, an electric vehicle comprising torque distribution control means for executing left and right wheel torque distribution control so that the output torque of the motor on the outer ring side is greater than the output torque of the motor on the inner ring side. Upper limit battery output setting means for setting an upper limit battery output according to the torque distribution control means, and the torque distribution control means is connected to the first motor 303 during the torque distribution control. When the total output of the second motor 308, the third motor 309, and the fourth motor 310 exceeds the upper limit battery output, the third motor 308 and the second motor 308 are subjected to output restriction before the output is limited. The third motor 309 and the fourth motor after the output restriction is applied to the motor on one outer ring side of the motor 309 and the fourth motor 310, and the output restriction is applied to the first motor 303 and the second motor 308. By limiting the output to the motor on the other inner ring side of 310, it is possible to suppress an oversteer tendency even if the output is limited because the SOC is low during turning, and a motor that individually drives the front, rear, left and right wheels is provided. The running stability of the electric vehicle can be ensured.

  As mentioned above, although the control apparatus of the electric vehicle of this invention has been demonstrated based on Example 1-3, it is not restricted to these Examples about a concrete structure, Each claim of a claim Design changes and additions are permitted without departing from the spirit of the invention according to the paragraph.

  In the first to third embodiments, an example of application to an electric four-wheel drive vehicle based on a front wheel drive is shown, but application to an electric four-wheel drive vehicle based on a rear wheel drive is also included in the present invention. In other words, in an electric four-wheel drive vehicle based on a front wheel drive, when the rear wheel drive force is increased to suppress understeer caused by excessive drive force of the main drive wheel (front wheel), the motor output limit caused by the battery condition Since the output restriction timing is shifted so as to maintain the yaw rate without simultaneously applying to each motor, it is possible to solve the problem of an oversteer tendency due to the restriction caused by the battery state. On the other hand, in an electric four-wheel drive vehicle based on a rear wheel drive, when the front wheel drive force is increased to suppress oversteer caused by excessive drive force of the main drive wheel (rear wheel), the motor caused by the battery condition Since the output restriction timing is shifted so as to maintain the yaw rate without simultaneously applying the output restriction to each motor, it is possible to solve the problem of an understeer tendency due to the restriction caused by the battery state.

  In the first to third embodiments, the application example to the front wheel drive-based electric vehicle has been described. However, as described above, the present invention can also be applied to the rear wheel drive-based electric four-wheel drive vehicle. In short, a plurality of motors, a battery that is electrically coupled to the plurality of motors, and a driving force distribution that controls the outputs of the plurality of motors according to the driving state so that the steering characteristic of the vehicle is neutral steer. The present invention can be applied to any vehicle provided with control means.

1 is an overall system diagram of an electric vehicle to which a control device of Example 1 is applied. 3 is a flowchart illustrating a flow of control executed by a CPU according to the first embodiment. It is a figure which shows an example of the torque reduction speed setting setting map used in Examples 1-3. It is a figure which shows an example of the torque reduction speed setting map used in Examples 1-3. It is a figure which shows an example of the output limitation rate setting map used in Examples 1-3. 3 is a time chart illustrating a change characteristic of a required torque of the motor in the first embodiment. It is a whole system figure of the electric vehicle to which the control apparatus of Example 2 was applied. 6 is a flowchart illustrating a flow of control executed by a CPU according to a second embodiment. 6 is a time chart showing a change characteristic of a required torque of a motor in Example 2. It is a whole system figure of the electric vehicle to which the control apparatus of Example 3 was applied. 10 is a flowchart illustrating a flow of control executed by a CPU according to a third embodiment. 6 is a time chart showing a change characteristic of a required torque of a motor in Example 3.

Explanation of symbols

101 CPU
102 Auxiliary battery 301 High power battery (battery)
302 FR inverter 303 First motor 304 Generator 305 Engine 306 Power split mechanism 307 RR inverter 308 Second motor 309 Third motor 310 Fourth motor 311 Differential mechanism 401 Accelerator sensor 402 Brake sensor 403 DC / DC converter 404 Steering angle Sensor 406 Wheel speed sensor 407 Yaw rate sensor 408 Warning light

Claims (12)

A plurality of electric motors as drive sources;
A battery for supplying power to the plurality of electric motors;
An electric vehicle comprising: torque distribution control means for controlling at least one of front and rear wheel torque distribution and left and right wheel torque distribution using output torques of the plurality of electric motors; and yaw rate detection means for detecting a yaw rate.
An upper limit battery output setting means for setting an upper limit battery output in accordance with a state of charge of the battery is provided, and the torque distribution control means is configured such that a total output of the plurality of electric motors exceeds the upper limit battery output during the torque distribution control. A control device for an electric vehicle, wherein output restriction is applied to the plurality of electric motors so as to hold the yaw rate detected by the yaw rate detection means. In the control device of the electric vehicle according to claim 1,
The electric vehicle includes an engine and a first electric motor that drive one of the front and rear wheels, a second electric motor that drives the other auxiliary driving wheel of the front and rear wheels, the first electric motor, and the second electric motor. An electric vehicle including a battery for supplying electric power to the electric motor,
When the total output of the first motor and the second motor exceeds the upper limit battery output during front and rear wheel torque distribution control using the output torque of the first motor and the second motor, the torque distribution control means A control device for an electric vehicle, wherein output restriction is applied to each of the first electric motor and the second electric motor so as to hold the yaw rate detected by the yaw rate detection means of the electric vehicle. In the control apparatus of the electric vehicle according to claim 2,
An apparatus for controlling an electric vehicle, wherein when the output restriction is applied to the first electric motor and the second electric motor, the output restriction is applied to the second electric motor before the first electric motor. In the control device of the electric vehicle according to claim 1,
The electric vehicle includes an engine and a first electric motor that drive one main driving wheel among the front and rear wheels, and a second motor and a third motor that individually drive the left and right wheels of the other auxiliary driving wheel among the front and rear wheels, An electric vehicle comprising a battery for supplying electric power to the first motor, the second motor, and the third motor;
The torque distribution control means is configured to control the first motor, the second motor, and the motor during front / rear wheel torque distribution control and left / right wheel torque distribution control using output torques of the first motor, the second motor, and the third motor. When the total output of the third motor exceeds the upper limit battery output, an output is provided to each of the first motor, the second motor, and the third motor so as to maintain the yaw rate detected by the yaw rate detection means of the electric vehicle. A control device for an electric vehicle characterized by applying a restriction. In the control apparatus of the electric vehicle according to claim 4,
When applying output restrictions to each of the younger brother 1 motor, the second motor, and the third motor,
One of the second motor and the third motor is an outer ring side motor, the first motor, and the second motor and the third motor are output in the order of the other inner ring side motor. A control device for an electric vehicle. In the control device of the electric vehicle according to claim 1,
The electric vehicle includes a first electric motor and a second electric motor that individually drive the left and right wheels of one of the front and rear wheels, and a third motor that individually drives the left and right wheels of the other auxiliary driving wheel of the front and rear wheels. An electric vehicle comprising: an electric motor and a fourth electric motor; the first electric motor; the second electric motor; the third electric motor; and a battery that supplies electric power to the fourth electric motor;
The torque distribution control means includes the first electric motor, the second electric motor, the third electric motor, and the fourth electric motor using the output torque of the front and rear wheels and the right and left wheel torque distribution control using the output torque of the fourth electric motor. When the total output of the second motor, the third motor, and the fourth motor exceeds the upper limit battery output, the first motor and the second motor are configured to maintain the yaw rate detected by the yaw rate detection means of the electric vehicle. An electric vehicle control device that limits output to each of an electric motor, the third electric motor, and the fourth electric motor. In the control apparatus of the electric vehicle according to claim 6,
When applying output restriction to each of the first electric motor, the second electric motor, the third electric motor, and the fourth electric motor, before applying the output restriction to the first electric motor and the second electric motor, the third electric motor and the One of the fourth motors is subjected to output restriction on one outer ring side motor, and the output restriction is applied to the first motor and the second motor, and then the other inner ring side motor among the third motor and the fourth motor A control device for an electric vehicle characterized in that output restriction is applied to the vehicle. A first electric motor for driving the front wheels;
A second electric motor for driving the rear wheels;
A battery for supplying power to the first motor and the second motor;
Torque distribution control means for performing front and rear wheel torque distribution control for decreasing the output torque of the first motor and increasing the output torque of the second motor during vehicle turning;
In an electric vehicle equipped with
Upper limit battery output setting means for setting an upper limit battery output in accordance with a state of charge of the battery is provided, and the torque distribution control means is configured such that a total output of the first motor and the second motor is the upper limit during torque distribution control. When the battery output is exceeded, the output control is applied to the second electric motor before the first electric motor. A first electric motor for driving the front wheels;
A second electric motor that drives one of the left and right rear wheels;
A third electric motor that drives the other of the left and right wheels of the rear wheel;
A battery for supplying power to the first motor, the second motor, and the third motor;
Torque distribution control means for executing left and right wheel torque distribution control so that the output torque of the outer ring side motor among the second motor and the third motor becomes larger than the output torque of the inner ring side motor during turning of the vehicle;
In an electric vehicle equipped with
Upper limit battery output setting means for setting an upper limit battery output in accordance with the state of charge of the battery is provided, and the torque distribution control means is configured to control the total of the first motor, the second motor, and the third motor during torque distribution control. When the output exceeds the upper limit battery output, the output is performed in the order of the outer ring side motor among the second motor and the third motor, the first motor, and the inner ring side motor among the second motor and the third motor. A control device for an electric vehicle characterized by applying a restriction. A first electric motor that drives one of the left and right wheels of the front wheel;
A second motor for driving the other of the left and right wheels of the front wheel;
A third electric motor that drives one of the left and right rear wheels;
A fourth electric motor for driving the other of the left and right wheels of the rear wheel;
A battery for supplying power to the first motor, the second motor, the third motor, and the fourth motor;
Torque distribution control means for executing left and right wheel torque distribution control so that the output torque of the outer ring side motor among the third motor and the fourth motor becomes larger than the output torque of the inner ring side motor during turning of the vehicle;
In an electric vehicle equipped with
An upper limit battery output setting means for setting an upper limit battery output according to the state of charge of the battery is provided, and the torque distribution control means is configured to control the first electric motor, the second electric motor, the third electric motor, and the like during the torque distribution control. When the total output of the fourth motor exceeds the upper limit battery output, before the first motor and the second motor are subjected to output restriction, one of the third motor and the fourth motor is applied to the motor on the outer ring side. An electric vehicle characterized in that an output restriction is applied and an output restriction is applied to the other inner ring side motor of the third electric motor and the fourth electric motor after the output restriction is applied to the first electric motor and the second electric motor. Control device. In the control apparatus of the electric vehicle described in any one of Claims 1-10,
An electric vehicle having a vehicle speed sensor for detecting a vehicle speed, wherein the amount of change in the reduced torque when the output is limited to the electric motor is set to be smaller as at least one of the vehicle speed and the required driving force is higher. Control device. In the control apparatus of the electric vehicle described in any one of Claims 1-11,
A control device for an electric vehicle, characterized in that the amount of change in the reduced torque when the output is limited to the electric motor is set to be larger as the turning yaw rate change rate of the vehicle during the output limit is larger.

Images