JP6955439B2 - Vehicle control device and vehicle control method - Google Patents

Description

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

Conventionally, in Patent Document 1 below, when it is determined that the reference time is T0 or more, the drive torque of the motor determined to be the reference time T0 or more is reduced from the reference torque Trq0, and the other motor is used. It is described that the required torque Trqd is satisfied by increasing the driving torque of the above.

Japanese Unexamined Patent Publication No. 2012-95378

However, in the technique described in the above patent document, the driving torque of one of the front motor and the rear motor is reduced and the driving torque of the other motor is increased, so that the front and rear driving force distribution changes significantly. There is a problem that it ends up. Therefore, there is a problem that the driver unexpectedly behaves and the vehicle behavior becomes unstable.

Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to suppress overload of motors for driving front wheels and rear wheels, and to stabilize vehicle behavior. It is an object of the present invention to provide a new and improved vehicle control device and a vehicle control method which are possible.

In order to solve the above problems, according to a certain viewpoint of the present invention, the first motor that generates the driving force of the front wheels of the vehicle is controlled, and the first motor is limited to the maximum rated torque that can be generated by the first motor. A first motor control unit that can switch between a first mode in which the motor is operated and a second mode in which the first motor is operated with a continuous rated torque lower than the maximum rated torque as the upper limit, and the rear wheels of the vehicle. The first mode in which the second motor that generates the driving force of the above is controlled and the second motor is operated with the maximum rated torque that can be generated by the second motor as the upper limit, and the continuous rated torque that is lower than the maximum rated torque. A second motor control unit capable of switching between a second mode for operating the second motor and a second mode for operating the second motor is provided as an upper limit, and the first motor control unit and the second motor control unit include the first motor and the first motor. When operation in the first mode is permitted for only one of the two motors, the first motor and the other of the second motors are controlled in the second mode, and the driving force distribution between the front wheels and the rear wheels is achieved. Based on this, a vehicle control device for controlling the driving force of one of the first motor and the second motor is provided.

When the first motor control unit and the second motor control unit are allowed to operate in the first mode with respect to the other of the first motor and the second motor, the first motor and the second motor Both driving forces may be controlled based on the driving force distribution of the front wheels and the rear wheels.

Further, when controlling one of the first motor and the second motor based on the driving force distribution, the control may be performed based on the stability factor of the vehicle.

Further, the driving force of one of the first motor and the second motor may be controlled based on the degree of deviation and the polarity of the target value and the measured value of the stability factor.

Further, when controlling one of the first motor and the second motor based on the driving force distribution, the driving force of one of the first motor and the second motor is controlled based on the side slip angular velocity of the vehicle. It may be something to do.

Further, the driving force of one of the first motor and the second motor may be controlled based on the degree of deviation and the polarity of the skid angular velocity and the yaw rate of the vehicle.

Further, when controlling one of the first motor and the second motor based on the driving force distribution, the driving force of one of the first motor and the second motor is controlled based on the yaw rate of the vehicle. It may be a thing.

Further, the driving force of one of the first motor and the second motor may be controlled based on the degree of deviation between the target value of the yaw rate and the measured value.

Further, when controlling one of the first motor and the second motor based on the driving force distribution, the first motor and the second motor so that the driving force distribution of the front wheels and the rear wheels falls within a predetermined range. It may control the driving force of one of the motors.

Further, the predetermined range may be a range in which the driving force distribution between the front wheels and the rear wheels is 40:60 to 60:40.

Further, the maximum rated torque may be a torque whose duration is limited when the first motor or the second motor is operated at the maximum rated torque.

Further, the continuous rated torque may be a torque whose duration is not limited when the first motor or the second motor is operated at the continuous rated torque.

Further, in order to solve the above problems, according to another viewpoint of the present invention, the first motor that generates the driving force of the front wheels of the vehicle and the second motor that generates the driving force of the rear wheels of the vehicle are The step of determining whether or not there is an overload, and when one of the first motor and the second motor is determined to be overloaded, the maximum rated torque that can be generated by the one motor is set as the upper limit. Based on the step of switching from the first mode of operating the one motor to the second mode of operating the one motor with the continuous rated torque lower than the maximum rated torque as the upper limit, and the driving force distribution of the front wheels and the rear wheels. Provided is a vehicle control method comprising a step of controlling the first motor and the other of the second motor.

As described above, according to the present invention, it is possible to suppress the overload of the motors that drive the front wheels and the rear wheels, and to stabilize the vehicle behavior.

It is a schematic diagram which shows the structure of the vehicle which concerns on one Embodiment of this invention. It is a schematic diagram which shows the structure of a control device and its surroundings in detail. It is a schematic diagram which shows the output characteristic of the motor of a front wheel. It is a schematic diagram which shows the output characteristic of the motor of a rear wheel. It is a characteristic diagram which shows the map which defined the relationship between the distribution ratio (horizontal axis) of the driving force of the front and rear motors, and the steering stability (vertical axis) of a vehicle. It is a flowchart which shows the process procedure in the control device of this embodiment. It is a schematic diagram which shows the ideal driving force diagram.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the present specification and the drawings, components having substantially the same functional configuration are designated by the same reference numerals, so that duplicate description will be omitted.

First, the configuration of the vehicle 500 according to the embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic view showing a configuration of a vehicle 500 according to an embodiment of the present invention. As shown in FIG. 1, in the vehicle 500, the four tires (wheels) 12, 14, 16, 18 of the front wheels and the rear wheels, the control device (controller) 100, the outside world recognition unit 200, and the tires 12, 14 of the front wheels rotate. The driving force of the motor 20, the motor 22 that controls the rotation of the rear wheel tires 16 and 18, the inverter 19 that controls the motor 20, the inverter 21 that controls the motor 22, and the driving force of the motor 20 to the tires 12 and 14. The wheel speed (vehicle speed) is detected from the rotations of the gearbox 23 and the drive shaft 24 to be transmitted, the gearbox 25 and the drive shaft 26 to transmit the driving force of the motor 22 to the tires 16 and 18, and the tires 12 and 14 of the front wheels. Wheel speed sensors 40, 42, wheel speed sensors 28, 30 that detect wheel speed (vehicle speed) from the rotation of each tire 16, 18 of the rear wheels, accelerator opening sensor 32, yaw rate sensor 33, front wheels 12, 14 are steered. Steering wheel 34, steering angle sensor 35 that detects the steering angle δ of the steering wheel, power steering mechanism 36, display device 38, speaker 39, temperature sensor 44 that detects the temperature of the front wheel motor 20, and rear wheel motor 22. It is configured to have a temperature sensor 46, which detects the temperature.

The configuration shown in FIG. 1 includes one motor 20 for driving the front wheels and one motor 22 for driving the rear wheels, but the configuration is not limited to this, and each of the four wheels is provided. A driving motor and a gearbox corresponding to each motor may be provided.

In the present embodiment, the control device 100 calculates the control driving force of the motors 20 and 22, and the control device 100 instructs the motors 20 and 22 to control the motors 20 and 22 in a coordinated manner.

FIG. 2 is a schematic diagram showing in detail the configuration of the control device 100 and its surroundings. As shown in FIG. 2, the control device 100 includes a traveling control unit 150 that controls the front and rear motors 20 and 22. The travel control unit 150 includes a first motor control unit 110 that controls the front wheel motor 20, a second motor control unit 120 that controls the rear wheel motor 22, a driving force distribution unit 140, and a motor operation state signal generation unit 145. It is configured to have. The motor operation state signal generation unit 145 generates a motor operation state signal indicating the operation state of the front wheel motor 20 and the rear wheel motor 22.

The first motor control unit 110 acquires an overload protection flag from the inverter 19 indicating that the operating state of the motor 20 is an overload state and protection of the motor 20 is required. Similarly, the second motor control unit 120 acquires an overload protection flag from the inverter 21 indicating that the operating state of the motor 22 is an overload state and protection of the motor 22 is required. The first motor control unit 110 and the second motor control unit 120 control the motors 20 and 22 so as to operate in the continuous rated mode when the overload protection flag is issued.

Hereinafter, the control performed by the control device 100 will be specifically described. When the driving force distribution unit 140 of the control device 100 acquires the accelerator opening from the accelerator opening sensor 32, it calculates the total required driving force of the vehicle 500 and transfers the total driving force to the front wheel motor 20 and the rear wheel motor 22. Allocate. The first motor control unit 110 sends a command value of the required driving force to the inverter 19 that controls the front wheel motor 20. The inverter 19 controls the front wheel motor 20 based on the command value of the required driving force of the front wheel motor 20. The second motor control unit 120 sends a command value of the required driving force to the inverter 21 that controls the rear wheel motor 22. The inverter 21 controls the rear wheel motor 22 based on the command value of the required driving force of the rear wheel motor 22. As a result, each of the motors 20 and 22 is controlled according to the required driving force.

FIG. 3 is a schematic view showing the output characteristics of the front wheel motor 20. Further, FIG. 4 is a schematic view showing the output characteristics of the rear wheel motor 22. 3 and 4 show the relationship between the driving force (vertical axis: torque) and the speed (horizontal axis: rotation speed) of the front wheel motor 20 or the rear wheel motor 22.

The operation modes of the motors 20 and 22 include a maximum rated mode and a continuous rated mode. In the maximum rated mode, the maximum torque value (maximum rated torque) that the motor can exert can be output, but the duration of the maximum torque value is limited. When the motor is used in the maximum rated mode, the amount of heat generated inside increases, which affects the deterioration of the motor and the like. Therefore, in the maximum rated mode, the duration (allowable time) of the maximum torque value is defined. On the other hand, in the continuous rated mode, the torque value is limited as compared with the maximum rated mode, and the torque value (continuous rated torque) capable of continuously outputting for a long time is set as the upper limit. 3 and 4 show the torque characteristics for each of the maximum rated mode and the continuous rated mode.

Here, in a situation where the motors 20 and 22 are overloaded, for example, when the driver wants to enjoy sports driving, the motors 20 and 22 may overheat. In such a case, for example, the heat generation of the motors 20 and 22 can be suppressed by switching to the control in the continuous rating mode based on the temperatures of the motors 20 and 22 detected by the temperature sensors 44 and 46. However, if the maximum rated mode is switched to the continuous rated mode in this way, the outputs of the motors 20 and 22 will suddenly go down, and the driver will not be able to perform the expected operation, or unexpectedly. There is a concern that vehicle behavior will occur and the behavior of the vehicle 500 will become unstable. In particular, if the specifications of the front and rear motors 20 and 22 are different, or if the loads applied to the front and rear motors 20 and 22 are not equal, one of the motors tends to overheat and the output may suddenly drop. .. Further, it is assumed that the vehicle behavior becomes unstable when one of the motors is switched from the maximum rated mode to the continuous rated mode and then returned to the maximum rated mode again.

In the present embodiment, since the motors 20 and 22 can be controlled independently, the stability of the vehicle 500 can be improved by optimally controlling the front-rear distribution of torque between the front wheel motor 20 and the rear wheel motor 22. Can be done. In particular, in the present embodiment, when only one of the front wheel motor 20 and the rear wheel motor 22 is allowed to operate in the maximum rated mode, the other of the front wheel motor 20 and the rear wheel motor 22 is stable in steering. Control the front and rear driving force distribution within the range that can ensure the performance.

As shown in FIG. 3, the front wheel motor 20 is driven in the maximum rated mode, and is driven by the torque (maximum rated torque) and the rotation speed indicated by the point A. Further, as shown in FIG. 4, the rear wheel motor 20 is driven in the maximum rated mode, and is driven by the torque (maximum rated torque) and the rotation speed indicated by the point A. In this case, if the operation of the front wheel motor 20 in the maximum rated mode exceeds the allowable range (allowable operation duration), the front wheel motor 20 is overloaded. In this case, the inverter 19 sends information (overload protection flag) indicating that an overload is applied to the first motor control unit 110.

Whether or not the motors 20 and 22 are in an overloaded state is determined based on the allowable operation duration described above, as well as various parameters (temperature, current value, voltage value, etc.) indicating the operating state of the motors 20 and 22. Can be determined according to the duration. For example, when the temperature of the motors 20 and 22 exceeds a predetermined threshold value exceeds the allowable duration, it is determined that the motors 20 and 22 are in an overloaded state. Further, when the state in which the current values of the motors 20 and 22 exceed a predetermined threshold value exceeds the allowable duration, it is determined that the motors 20 and 22 are in an overloaded state. Similarly, when the state in which the voltage values of the motors 20 and 22 exceed a predetermined threshold value exceeds the allowable duration, it is determined that the motors 20 and 22 are in an overloaded state. In either case, the overload protection flag is sent to the first motor control unit 110 or the second motor control unit 120. When the motors 20 and 22 determine the overload state based on the temperature, the first motor control unit 110 and the second motor control unit 120 determine the overload state based on the detected values of the temperature sensors 44 and 46. The motors 20 and 22 are controlled based on the determination result.

In the determination based on the various parameters described above, the determination may be performed using any one parameter, or the determination may be performed by combining a plurality of parameters. Further, by sending these parameters to the control device 100 via CAN (Control Area Network) or the like, the control device 100 may make a determination.

When the first motor control unit 110 receives the overload protection flag from the inverter 19, the first motor control unit 110 controls to lower the front wheel motor 20 from the maximum rated mode to the continuous rated mode. As a result, the front wheel motor 20 is driven by the torque (continuous rated torque) and the number of revolutions indicated by the point B in FIG. Further, the first motor control unit 110 sends information to the second motor control unit 120 that the front wheel motor 20 has been dropped from the maximum rated mode to the continuous rated mode.

When the second motor control unit 120 receives information from the first motor control unit 110 that the front wheel motor 20 has been dropped from the maximum rated mode to the continuous rated mode, the rear wheel motor 22 has a torque lower than the maximum rated torque. Control with. As a result, the rear wheel motor 22 is driven by the torque (continuous rated torque) and the number of revolutions indicated by the point C in FIG. Therefore, by driving the rear wheel motor 22 with a torque lower than the maximum rated torque, it is possible to suppress a large change in the front-rear driving force distribution and stabilize the vehicle behavior. If the torque of the rear wheel motor 22 is not reduced, for example, the front and rear driving force distribution is about 30:70 for the front wheels and the rear wheels, and there is a concern that the vehicle 500 tends to spin. When the front wheel motor 20 is lowered to the continuous rated mode, such a situation can be reliably avoided by reducing the torque of the rear wheel motor 22.

More specifically, with respect to the rear wheel motor 22, since the overload protection flag is not originally issued, it is possible to control the output with the maximum rated torque as the upper limit. Therefore, the torque of the rear wheel motor 22 can be controlled while adjusting the driving force distribution between the front wheels and the rear wheels so that the steering stability becomes a predetermined level.

In the above description, the case where the front wheel motor 20 is dropped from the maximum rated mode to the continuous rated mode is described. However, even when the rear wheel motor 22 is dropped from the maximum rated mode to the continuous rated mode, the front wheels are also described. The control of the motor 20 is performed in the same manner as the control of the rear wheel motor 22 described above.

If the overload protection flag is not issued from any of the inverters 19 and 21, the operation of the motors 20 and 22 is continued without changing the operation modes of the front and rear motors 20 and 22.

As described above, when the motor 20 is driven with the maximum rated torque, the amount of heat generated inside the motor 20 increases, which causes deterioration of the motor. Therefore, deterioration of the motor 20 can be suppressed by changing the operation mode of the motor 20 from the maximum rated mode to the continuous rated mode in response to the acquisition of the overload protection flag from the inverter 19.

In particular, when the specifications of the front wheel motor 20 and the rear wheel motor 22 are different, or when the front and rear torque distribution is not evenly controlled, an overload protection flag may be issued for one of the motors 20. In such a case, if only one of the motors 20 is dropped from the maximum rated mode to the continuous rated mode, the front and rear torque distribution will change, the driver will not be able to drive as expected, or unexpected vehicle behavior will occur. there's a possibility that.

In the present embodiment, when one of the front wheel motor 20 and the rear wheel motor 22 is switched from the maximum rated mode to the continuous rated mode, the steering stability of the other of the front wheel motor 20 and the rear wheel motor 22 is improved. Control is performed while adjusting the front and rear driving force distribution so as to satisfy a predetermined level. As a result, even if one of the motors is switched from the maximum rated mode to the continuous rated mode, the torque distribution in the front and rear does not change significantly, and the behavior stability of the vehicle 500 can be maintained.

The other motor without the overload protection flag can be driven with a torque equal to or higher than the continuous rated torque. Therefore, as shown by point C in FIG. 4, for the other motor for which the overload protection flag is not issued, the front and rear driving force distribution is adjusted so that the maneuverability becomes a predetermined level. , Control the driving force. As a result, when the overload protection flag is issued to one motor and the mode is switched from the maximum rated mode to the continuous rated mode, the other motor without the overload protection flag generates an output according to the running condition. Therefore, it is possible to suppress poor acceleration and deterioration of maneuverability. When one of the front wheel motor 20 and the rear wheel motor 22 is switched from the maximum rated mode to the continuous rated mode, the other of the front wheel motor 20 and the rear wheel motor 22 is also once switched to the continuous rated mode, and then The torque may be increased.

In addition, after switching one of the front wheel motor 20 and the rear wheel motor 22 from the maximum rated mode to the continuous rated mode due to the overload protection flag being issued, it is permissible to operate the other motor in the maximum rated mode. When the condition is reached, the motor is controlled to increase the torque. As shown by point D in FIG. 3, when the overload protection flag is released by poking the front wheel motor 20 for which the overload protection flag is issued, torque is increased from the continuous rated torque, and FIG. 4 Control is performed at the rotation speed and torque indicated by the point D inside.

In the following, in the examples shown in FIGS. 3 and 4, the method of controlling the torque and the number of revolutions from the point A to the point C in FIG. 4 will be described in detail for the rear wheel motor 22 in which the overload protection flag is not issued. explain. After the rear wheel motor 22 is lowered to the continuous rated mode, the front and rear outputs are changed to a distribution that can secure the maneuverability according to the traveling state within the range of the margin of the circle of forces utilization rate. Specific methods include a method based on the stability factor A, a method based on the skid angle, and a method based on the yaw rate γ. The front-rear distribution is calculated by the driving force distribution unit 140, and the first motor control unit 110 and the second motor control unit 120 control the front-rear motors 20 and 22 based on the front-rear distribution calculated by the driving force distribution unit 140. ..

In the method based on the stability factor A, the stability factor A is calculated from the vehicle speed V, the yaw rate γ, and the steering angle δ of the steering wheel, and the understeer of the vehicle 500 is obtained from the deviation from the preset target value (considering the polarity). The strength of the (US) tendency (plow tendency) or the oversteer (OS) tendency (spin tendency) is obtained, and the output of the rear wheel motor 22 is limited based on the magnitude.

The stability factor A is an index showing the potential of steering stability of the vehicle 500. The target value of the stability factor A can be calculated from the following equation (1).

In equation (1), m is the vehicle weight, l is the wheelbase, If is the front axle to the center of gravity point distance, Ir is the rear axle to the center of gravity point distance, Kf is the front wheel cornering power, and Kr is the rear wheel cornering power. There is.

In the formula (1), when lf · Kf−lr · Kr = 0, it indicates that the vehicle 500 is in neutral steering (NS). Further, when lf · Kf−lr · Kr <0, it indicates that the vehicle 500 tends to understeer. Further, when lf · Kf−lr · Kr> 0, it indicates that the vehicle 500 tends to oversteer.

The target value of the stability factor A can also be the sliding angular velocity (= γ-Ay / V).

Further, the measured value of the stability factor A can be calculated by solving the following equation (2) for the stability factor A based on the vehicle speed V, the yaw rate γ, the steering angle δ, and the wheelbase l.

In the determination based on the stability factor A, the target value is calculated from the specifications of the vehicle 500 based on the equation (1). Further, the measured value of the stability factor A is calculated from the vehicle speed V, the yaw rate γ, and the steering angle δ based on the equation (2). Then, the target value and the measured value are compared, and if the sign of the target value and the measured value is the same and the difference between the absolute values of the two exceeds the threshold, it is judged that the vehicle is oversteered and the driving force is distributed toward the front wheels. And. If the sign of the target value and the measured value are different and the difference between the absolute values of the two exceeds the threshold value, it is determined that the vehicle is understeered, and the driving force is distributed closer to the rear wheels.

Further, the side slip angular velocity (vehicle body slip angular velocity) of the vehicle 500 can be obtained from the following equation (3).

In equation (3), the first derivative of the sideslip angle β indicates the sideslip angular velocity, and the second derivative of the lateral movement amount y indicates the lateral acceleration.

In the judgment based on the skid angular velocity, if the sign of the yaw rate γ and the sign of the vehicle body slip angular velocity are the same and the difference between the absolute values of the two exceeds a predetermined threshold value, it is judged as an oversteer state and the rear wheels are cornered. In order to secure power, the driving force will be distributed closer to the front wheels.

If the sign of yaw rate γ and the sign of skid angular velocity are different and the difference between the absolute values of the two exceeds a predetermined threshold value, it is judged to be understeer and the front wheels are closer to the rear wheels in order to secure the cornering power. The driving force distribution of.

The yaw rate γ (target yaw rate) of the vehicle 500 can be calculated from the following equation (4). The equation (4) shows the same equation as the equation (2).

In the determination based on the yaw rate γ, the target yaw rate γ calculated from the steering angle δ and the vehicle speed V is compared with the actual yaw rate detected by the yaw rate sensor 33 based on the equation (4). If the absolute value of the actual yaw rate is smaller than the absolute value of the target yaw rate, the actual turning amount of the vehicle 500 is small and there is a tendency for understeer. And. If the absolute value of the actual yaw rate is larger than the absolute value of the target yaw rate, the actual turning amount of the vehicle 500 is large and the vehicle tends to oversteer. Therefore, the driving force toward the front wheels is reduced in order to reduce the cornering power of the rear wheels. It will be allocated.

When torque-up the rear wheel motor 22 to the point C in FIG. 4, a map that integrates the above-mentioned contents can be created, and control can be performed based on the map. FIG. 5 is a characteristic diagram showing a map defining the relationship between the distribution ratio of the driving force of the front and rear motors 20 and 22 (horizontal axis) and the steering stability of the vehicle (vertical axis). In FIG. 5, the distribution ratio on the horizontal axis indicates the ratio of the driving force of the front wheel motor 20 to the total driving force of the front and rear motors 20 and 22. A plurality of maps shown in FIG. 5 may be provided according to the driving state (vehicle speed, etc.) of the vehicle 500. Further, the map shown in FIG. 5 may be created according to the fit of the actual vehicle.

When the steering stability of the vehicle 500 exceeds the permissible limit shown in FIG. 5, the vehicle behavior becomes stable. On the other hand, if the steering stability is equal to or less than the permissible limit shown in FIG. 5, the vehicle behavior becomes unstable. In the example shown in FIG. 5, the vehicle behavior is stabilized by setting the ratio of the driving force of the front wheel motor 20 to the total driving force of the front and rear motors 20 and 22 within the range of 40% to 60%. That is, the front and rear driving force distribution is front wheel 40: rear wheel 60.
~ Front wheel 60: It is desirable to limit the range to the rear wheel 40.

FIG. 7 is a schematic diagram showing an ideal driving force diagram. The ideal driving force diagram shown in FIG. 7 shows the ideal driving force distribution of the front wheels or the rear wheels with respect to the vehicle acceleration, and is obtained from the vehicle weight, the wheelbase, the height of the center of gravity, and the roll ratio.

In FIG. 7, the horizontal axis shows the ratio (= Fx (front) / Fzf) of the front-rear force Fx (front) of the front wheels to the ground contact load Fzf of the front wheels. Here, assuming that the ground contact load of the front wheels when stationary is Fzf0 and the load transfer amount due to acceleration is ΔFzx, the ground contact load Fzf of the front wheels can be calculated from the following equation (5).
Fzf = Fzf0-ΔFzx ... (5)

Further, in FIG. 7, the vertical axis shows the ratio (= Fx (rear) / Fzr) of the front-rear force Fx (rear) of the rear wheels to the ground contact load Fzr of the rear wheels. Here, assuming that the ground contact load of the rear wheels when stationary is Fzr0 and the load transfer amount due to acceleration is ΔFzx, the ground contact load Fzr of the rear wheels can be calculated from the following equation (6).
Fzr = Fzr0 + ΔFzx. ... (6)

Further, the load shift amount due to acceleration ΔFzx the vehicle weight m, the longitudinal acceleration a, the center of gravity height h _g, using the wheelbase l, can be calculated from the following equation (7).
ΔFzx = (m ・ a ・ h _g ) / (2 ・ l) ・ ・ ・ (7)

In FIG. 7, the curve shown by the solid line shows the characteristics of the vehicle 500 when traveling straight. Further, the curve shown by the alternate long and short dash line shows the characteristics of the vehicle 500 when turning.

Further, in FIG. 7, the five alternate long and short dash lines have a road surface friction coefficient μ of μ = 0.2, μ = 0.4, μ = 0.6, μ = 0.8, and μ = 1.0, respectively. The case of is shown. Further, the five broken lines indicate the cases where the acceleration is 0.2 G, 0.4 G, 0.6 G, 0.8 G, and 1.0 G, respectively.

According to FIG. 7, in the case of going straight, at an acceleration of 0.2 G, the ideal driving force distribution is about 52:48 for the front and rear wheels, and in this state, on the road surface of μ = 0.2. The driving force can be output to the limit. At an acceleration of 0.6G, the ideal driving force distribution is about 47:53 for the front wheels and rear wheels, and in this state, the driving force is output to the limit on the road surface of μ = 0.6. can do.

As a control method based on FIG. 7, basically, the front and rear driving forces are distributed so as to have the ideal driving force distribution shown in the region R. That is, front wheel: rear wheel = 40:60 to front wheel: rear wheel = 60:40. For example, in FIG. 7, when the motor 20 of the front wheels changes from the maximum rated mode to the continuous rated mode while traveling at the point E, if the front-rear distribution is set to the point F (front wheels: rear wheels = 30:70), the vehicle 500 Since it becomes unstable, it is limited to the point G (front wheel: rear wheel = 40:60). As a result, the vehicle 500 can be driven within the region of the ideal driving force distribution by suppressing the driving force of the rear wheel motor 22. Similarly, when the rear wheel motor 22 changes from the maximum rated mode to the continuous rated mode while traveling at point E, the driving force of the front wheel motor 20 is similarly suppressed in order to suppress a decrease in the driving force distribution of the rear wheels. Is controlled, and the front-rear distribution is limited to the point H (front wheel: rear wheel = 60:40). In this way, by controlling the front-rear driving force distribution within the region R indicated by the thick alternate long and short dash line, it is possible to improve the steering stability of the vehicle 500.

Further, by estimating the road surface friction coefficient, the upper limit of the acceleration when the vehicle 500 accelerates can be determined more accurately based on FIG. 7. For the estimation of the road surface friction coefficient, for example, the method described in JP-A-2006-46936 can be used. As a result, the vehicle 500 can be driven at an acceleration corresponding to the coefficient of friction of the road surface within the range of the region R.

Next, the processing procedure in the control device 100 of the present embodiment will be described based on the flowchart of FIG. The process of FIG. 6 is performed at predetermined control cycles. First, in step S10, the motor operation state signal is acquired.

The motor operation state signal is generated by the motor operation state signal generation unit 145. The motor operation state signal generation unit 145 confirms the states of the overload protection flag of the front wheel motor 20 and the overload protection flag of the rear wheel motor 22. Then, when the motor operating state signal generation unit 145 does not issue the overload protection flag to the front wheel motor 20 and the overload protection flag is issued to the rear wheel motor 22, only the front wheel motor 20 is displayed. Since the maximum rated mode is allowed, the motor operating state signal "1" is generated. Further, in the motor operation state signal generation unit 145, when the overload protection flag is issued to the front wheel motor 20 and the overload protection flag is not issued to the rear wheel motor 22, only the rear wheel motor 22 is displayed. Since the maximum rated mode is allowed, the motor operating state signal "2" is generated. Further, in the motor operation state signal generation unit 145, when the overload protection flag is issued to both the front wheel motor 20 and the rear wheel motor 22, the maximum rated mode is not allowed for either the front and rear motors 20 and 22. Therefore, the motor operation state signal "3" is generated.

In step S12, it is determined whether or not the motor operation state signal is “1”, and if the motor operation state signal is “1”, the process proceeds to step S14. In step S14, the output of the front wheel motor 20 is controlled so that the steering stability can be ensured according to the traveling state within the range of the margin of the circle of forces utilization rate.

After step S14, the process proceeds to step S16. In step S16, it is determined whether or not the rear wheel motor 22 is allowed to operate in the maximum rated mode, and if the operation in the maximum rated mode is permitted, the process proceeds to step S18. In step S18, the outputs of the front wheel and rear wheel motors 20 and 22 are controlled so as to ensure the maneuverability according to the traveling state. As a result, the front wheel motor 20 is controlled by the rotation speed and torque indicated by the point D in FIG.

On the other hand, if the motor operation status signal is not "1" in step S12, the process proceeds to step S20. In step S20, it is determined whether or not the motor operation state signal is “2”, and if the motor operation state signal is “2”, the process proceeds to step S22. In step S22, the output of the rear wheel motor 22 is controlled so that the distribution can ensure the maneuverability according to the traveling state within the range of the margin of the circle of forces utilization rate.

After step S22, the process proceeds to step S24. In step S24, it is determined whether or not the front wheel motor 20 is allowed to operate in the maximum rated mode, and if the operation in the maximum rated mode is permitted, the process proceeds to step S18. In step S18, the outputs of the front wheel and rear wheel motors 20 and 22 are controlled so as to ensure the maneuverability according to the traveling state.

The output control of the front wheel or rear wheel motors 20 and 22 in steps S14, S18 and S22 is determined based on the above-mentioned stability factor A, skid angular velocity, or yaw rate γ, and the front wheel motor 20 or the rear wheel motor 22 is controlled. It is done by adjusting the driving force distribution of. At this time, the driving force distribution unit 140 calculates the adjusted driving force distribution, and based on the calculated driving force distribution, the first motor control unit 110 and the second motor control unit 120 are the front wheel or rear wheel motor 20. , 22 are controlled.

Further, in the determination in steps S16 and S24, the determination is made depending on whether or not the overload protection flag is cleared. For example, in step S16, when the overload protection flag issued for the rear wheel motor 22 is released, it is determined that the rear wheel motor 22 can be operated in the maximum rated mode. The same applies to step S24.

Further, when the motor operation status signal is not "2" in step S20, that is, when the motor operation status signal is "3", the front and rear motors 20 and 22 are continuously operated in the continuous rated mode, and the next cycle is continued. (Step S10 or later).

In the above description, a configuration including one motor 20 for driving the front wheels and one motor 22 for driving the rear wheels has been described as an example. When each motor is provided to drive each wheel, when one motor of the front wheel falls from the maximum rated mode to the continuous rated mode, the rear wheel motor is controlled based on the front and rear driving force distribution by the above-mentioned method. It can be carried out.

As described above, according to the present embodiment, when one of the front wheel motor 20 and the rear wheel motor 22 exceeds the allowable range of the maximum rated mode and falls from the maximum rated mode to the continuous rated mode, the other , Control the front and rear driving force distribution within the range where steering stability can be ensured. As a result, it is possible to suppress deterioration of the motor that exceeds the allowable range of the maximum rated mode, secure the driving force without causing a large change in the torque distribution in the front and rear, and maintain the steering stability of the vehicle 500. Become.

Further, when one of the front wheel motor 20 and the rear wheel motor 22 is in a state where the operation in the maximum rated mode is permitted, the steering stability of one of the front wheel motor 20 and the rear wheel motor 22 is also improved. Control the front and rear driving force distribution within the range that can be secured. As a result, the driving force of the vehicle 500 can be increased while maintaining the steering stability of the vehicle 500.

Although the preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings, the present invention is not limited to such examples. It is clear that a person having ordinary knowledge in the field of technology to which the present invention belongs can come up with various modifications or modifications within the scope of the technical ideas described in the claims. , These are also naturally understood to belong to the technical scope of the present invention.

19, 21 Inverter 20, 22 Motor 100 Control device 110 1st motor control unit 120 2nd motor control unit 106 Driving force distribution control unit 500 Vehicle

Claims (13)

The first mode in which the first motor that generates the driving force of the front wheels of the vehicle is controlled and the first motor is operated with the maximum rated torque that can be generated by the first motor as the upper limit, and the continuous lower than the maximum rated torque. A first motor control unit that can switch between a second mode in which the first motor is operated with the rated torque as the upper limit, and a first motor control unit that can switch between the first motor and the second mode.
The first mode in which the second motor that generates the driving force of the rear wheels of the vehicle is controlled and the second motor is operated with the maximum rated torque that can be generated by the second motor as the upper limit, and the maximum rated torque It is provided with a second motor control unit that can switch between a second mode in which the second motor is operated with a low continuous rated torque as an upper limit.
The first motor control unit and the second motor control unit are the first motor and the second motor when only one of the first motor and the second motor is allowed to operate in the first mode. The other of the motors is controlled in the second mode, and the driving force of one of the first motor and the second motor is controlled based on the driving force distribution of the front wheels and the rear wheels. Control device. When the first motor control unit and the second motor control unit are allowed to operate in the first mode with respect to the other of the first motor and the second motor, the first motor and the second motor The vehicle control device according to claim 1, wherein both driving forces are controlled based on the driving force distribution of the front wheels and the rear wheels. The vehicle control device according to claim 1, wherein when one of the first motor and the second motor is controlled based on the driving force distribution, the control is performed based on the stability factor of the vehicle. .. The vehicle according to claim 3, wherein the driving force of one of the first motor and the second motor is controlled based on the degree of deviation and the polarity of the target value and the measured value of the stability factor. Control device. When controlling one of the first motor and the second motor based on the driving force distribution, the driving force of one of the first motor and the second motor is controlled based on the side slip angular velocity of the vehicle. The vehicle control device according to claim 1. The vehicle control device according to claim 5, wherein the driving force of one of the first motor and the second motor is controlled based on the degree of deviation and polarity of the skid angular velocity and the yaw rate of the vehicle. When controlling one of the first motor and the second motor based on the driving force distribution, controlling the driving force of one of the first motor and the second motor based on the yaw rate of the vehicle. The vehicle control device according to claim 1, which is characterized. The vehicle control device according to claim 7, wherein the driving force of one of the first motor and the second motor is controlled based on the degree of deviation between the target value of the yaw rate and the measured value. When controlling one of the first motor and the second motor based on the driving force distribution, the first motor and the second motor are used so that the driving force distribution of the front wheels and the rear wheels is within a predetermined range. The vehicle control device according to claim 1, wherein one of the driving forces is controlled. The vehicle control device according to claim 9, wherein the predetermined range is a range in which the driving force distribution between the front wheels and the rear wheels is in the range of 40:60 to 60:40. The maximum rated torque according to any one of claims 1 to 10, wherein the maximum rated torque is a torque whose duration is limited when the first motor or the second motor is operated at the maximum rated torque. Vehicle control device. The continuous rated torque according to any one of claims 1 to 11, wherein the continuous rated torque is a torque whose duration is not limited when the first motor or the second motor is operated at the continuous rated torque. Vehicle control device. A step of determining whether or not the first motor that generates the driving force of the front wheels of the vehicle and the second motor that generates the driving force of the rear wheels of the vehicle are overloaded.
From the first mode in which when one of the first motor and the second motor is determined to be overloaded, the one motor is operated up to the maximum rated torque that can be generated by the one motor. The step of switching to the second mode in which one of the motors is operated with the continuous rated torque lower than the maximum rated torque as the upper limit, and
A step of controlling the first motor and the other of the second motor based on the driving force distribution of the front wheels and the rear wheels.
A vehicle control method, characterized in that the vehicle is provided with.

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