JP6966940B2 - 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 an overload of a motor that drives each of the front wheels and the rear wheels, and to stabilize the 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 wheel 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 are the first motor and the first motor. When the operation of at least one of the two motors is switched from the first mode to the second mode, the operation of the first motor and the other of the second motors is also switched from the first mode to the second mode. After that, a vehicle control device for controlling the driving force of the first motor and the other of the second motor based on the driving force distribution of the front wheels and the rear wheels is provided.

After switching the operation of the other of the first motor and the second motor from the first mode to the second mode, the other of the first motor and the second motor is driven based on the stability factor of the vehicle. It may control the force.

Further, the driving force of the other 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, after switching the operation of the other of the first motor and the second motor from the first mode to the second mode, the other of the first motor and the second motor is based on the side slip angular velocity of the vehicle. It may control the driving force.

Further, the driving force of the other 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, after switching the operation of the other of the first motor and the second motor from the first mode to the second mode, the other of the first motor and the second motor is driven based on the yaw rate of the vehicle. It may control the force.

Further, the driving force of the other 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, after switching the operation of the other of the first motor and the second motor from the first mode to the second mode, the first motor is set so that the driving force distribution between the front wheels and the rear wheels is within a predetermined range. And the other driving force of the second motor may be controlled.

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 first motor control unit may switch the operation of the first motor from the first mode to the second mode when the operating state of the first motor is overloaded.

Further, the second motor control unit may switch the operation of the second motor from the first mode to the second mode when the operating state of the second motor is overloaded.

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 the maximum rated torque that can be generated by the one motor when at least one of the first motor and the second motor is determined to be overloaded. The step of switching from the first mode in which the one motor is operated with the upper limit to the second mode in which the one motor is operated with the continuous rated torque lower than the maximum rated torque as the upper limit, and the first motor and the first mode. When the other of the two motors is also operated in the first mode in which the maximum rated torque that can be generated is the upper limit, the step of switching to the second mode in which the continuous rated torque lower than the maximum rated torque is the upper limit is operated. And a step of controlling the driving force of the other of the first motor and the second motor based on the driving force distribution of the front wheels and the rear wheels is provided.

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 procedure of the process in the control apparatus 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, and 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 diagram 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 rotation 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. Steering the wheel speed sensors 40, 42, the wheel speed sensors 28, 30, which detect the wheel speed (vehicle speed) from the rotation of the rear tires 16 and 18, the accelerator opening sensor 32, the yaw rate sensor 33, and the front wheels 12, 14. 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 not limited to this. 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 composed of. 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 necessary. 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 are configured to operate both the motors 20 and 22 in the continuous rated mode when the overload protection flag is issued for any of the motors 20 and 22. Take control.

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 degree from the accelerator opening degree 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 diagram showing the output characteristics of the front wheel motor 20. Further, FIG. 4 is a schematic diagram 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 and affects the deterioration of the motor. 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 more than in the maximum rated mode, and the torque value (continuous rated torque) that can be continuously output 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, by switching to the control by the continuous rating mode based on the temperature of the motors 20 and 22 detected by the temperature sensors 44 and 46, the heat generation of the motors 20 and 22 can be suppressed. However, if the maximum rated mode is switched to the continuous rated mode by such a method, the outputs of the motors 20 and 22 will suddenly go down, and the operation expected by the driver may not be possible or unexpected. 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 even, 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 each of 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 one of the front wheel motor 20 and the rear wheel motor 22 falls from the maximum rated mode to the continuous rated mode, the other of the front wheel motor 20 and the rear wheel motor 22 also changes from the maximum rated mode. Control to drop to continuous rated mode.

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 the 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 overload 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 overload 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 overload 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 made using any one parameter, or the determination may be made 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.

Upon receiving 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 second motor control unit 120 changes the rear wheel motor 22 from the maximum rated mode to the continuous rated mode. Drop it to. 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 B in FIG. Therefore, by driving the rear wheel motor 22 with the continuous rated torque as the upper limit, it is possible to suppress a large change in the front-rear driving force distribution and stabilize the vehicle behavior. If the motor 22 of the rear wheels is not lowered to the continuous rated mode, for example, the front and rear driving force distribution is about 30:70 for the front wheels: the rear wheels, and there is a concern that the vehicle 500 tends to spin. When the front wheel motor 20 is dropped to the continuous rated mode, by dropping the rear wheel motor 22 to the continuous rated mode, such a situation can be reliably avoided.

After both the front wheel motor 20 and the rear wheel motor 22 are in the continuous rated mode, the drive torque of the rear wheel motor 22 is larger than the continuous rated torque because the overload protection flag is not originally issued. can do. Therefore, the rear wheel motor 22 is controlled to increase the torque while adjusting the driving force distribution between the front wheels and the rear wheels so that the steering stability becomes a predetermined level. As a result, the rear wheel motor 22 is driven by the torque and the rotation speed indicated by the point C in FIG.

In the above description, when the front wheel motor 20 is dropped from the maximum rated mode to the continuous rated mode, the rear wheel motor 22 is dropped from the maximum rated mode to the continuous rated mode as an example. Similarly, when the rear wheel motor 22 is dropped from the maximum rated mode to the continuous rated mode, control is performed so that the front wheel motor 20 is dropped from the maximum rated mode to the continuous rated mode.

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 reducing 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. In such a case, if only one of the motors is dropped from the maximum rated mode to the continuous rated mode, the torque distribution in the front and rear will change, the driver will not be able to drive as expected, and unexpected vehicle behavior will occur. there is a possibility.

In this 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 other of the front wheel motor 20 and the rear wheel motor 22 is also continuously rated from the maximum rated mode. Controls to switch to the mode. As a result, even if one motor switches from the maximum rated mode to the continuous rated mode, the other motor also switches from the maximum rated mode to the continuous rated mode at the same time, so that the torque distribution before and after does not change significantly. , It is possible to maintain the behavioral stability of the vehicle 500.

Further, after both the motors 20 and 22 are set to the continuous rated mode, one of the motors for which the overload protection flag is not issued 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 one of the motors for which the overload protection flag is not issued, the front and rear driving force distribution is adjusted so that the steering stability becomes a predetermined level. , Torque up. As a result, one of the motors for which the overload protection flag is not issued generates an output according to the traveling state, so that it is possible to suppress acceleration failure and deterioration of steering stability.

In the following, in the examples shown in FIGS. 3 and 4, the method of controlling the torque and the rotation speed from the point B 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 dropped to the continuous rated mode, the front and rear outputs are changed to the distribution that can secure the maneuverability according to the running condition 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 oversteer (OS) tendency (spin tendency) is obtained, and the output of the rear wheel motor 22 is limited by the magnitude thereof.

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 means that the vehicle 500 is neutral steering (NS). Further, when lf, Kf-lr, Kr <0, it is shown that the vehicle 500 tends to understeer. Further, when lf ・ Kf-lr ・ Kr> 0, it is shown that the vehicle 500 tends to oversteer.

The target value of the stability factor A can also be set to the slip 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 as an oversteer state 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 understeer and the driving force is distributed toward 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 the 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 sideslip 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 cornering of the rear wheels. In order to secure power, the driving force will be distributed closer to the front wheels.

If the sign of the yaw rate γ and the sign of the side slip 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. Driving force distribution.

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 closer to the front wheels is used to reduce the cornering power of the rear wheels. It will be distributed.

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 operating 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 to the range of 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 wheel to the ground contact load Fzf of the front wheel. Here, assuming that the ground contact load of the front wheels at rest 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 at rest 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 thick broken line shows the characteristics of the vehicle 500 when traveling straight. Further, the curve shown by the thick solid line shows the characteristics of the vehicle 500 when turning.

Further, in FIG. 7, the five one-dot chain lines, two-dot chain lines, and three-dot chain lines have a road surface friction coefficient μ of μ = 0.2, μ = 0.4, μ = 0.6, μ = 0.8, Each case of μ = 1.0 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. Further, at an acceleration of 0.6 G, the ideal driving force distribution is such that the front and rear driving force distribution is about 47:53 for the front wheels: 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 be 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 wheel 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 wheel: rear wheel = 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, it is possible to improve the steering stability of the vehicle 500 by controlling the front-rear driving force distribution within the region R indicated by the thick one-dot chain line.

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 Japanese Patent Application Laid-Open No. 2006-46936 can be used. As a result, the vehicle 500 can be driven at an acceleration corresponding to the road surface friction coefficient within the range of the region R.

Next, the processing procedure in the control device 100 of the present embodiment will be described with reference to the flowchart of FIG. The process of FIG. 6 is performed at predetermined control cycles. First, in step S10, the state of the overload protection flag sent from the inverter 19 and the inverter 21 is confirmed. In the next step S11, it is determined whether or not the overload protection flag has been sent from at least one of the inverter 19 and the inverter 21. Then, if the overload protection flag is sent, the process proceeds to step S12. On the other hand, if the overload protection flag is not sent, the process waits in step S11.

In step S12, it is determined whether or not any of the front and rear motors 20 and 22 is operating in the maximum rated mode, and if any motor is operating in the maximum rated mode, the process proceeds to step S14. .. In step S14, both the front and rear motors 20 and 22 are operated in the continuous rated mode.

After step S14, the process proceeds to the process after step S16, and the process according to the motor operation status signal is performed. Here, when the motor operating state signal is "1", the maximum rated mode is allowed only for the front wheel motor 20. Further, when the motor operating state signal is "2", the maximum rated mode is allowed only for the rear wheel motor 22. Further, when the motor operation status signal is "3", the operation of the front and rear motors 20 and 22 with the maximum rated motor is not allowed.

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 motor 20 of the front wheel and the overload protection flag of the motor 22 of the rear wheel. When the motor operation state signal generation unit 145 does not output the overload protection flag to the front wheel motor 20 and the rear wheel motor 22 has the overload protection flag, only the front wheel motor 20 is displayed. Since the maximum rated mode is allowed, the motor operation status 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 operation status 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.

First, in step S16, 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 S18. In step S18, 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.

On the other hand, if the motor operation status signal is not "1" in step S16, 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.

The control of the output of the front wheel or rear wheel motors 20 and 22 in steps S18 and S22 is to drive the front wheel motor 20 or the rear wheel motor 22 based on the determination based on the stability factor A, the sideslip angular velocity, or the yaw rate γ described above. It is done by adjusting the force distribution. 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, 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 of the motors for driving each wheel is provided, it is possible to control all the motors to be in the continuous rated mode when the motor of one of the front wheels falls from the maximum rated mode to the continuous rated mode. Further, after all the motors are set to the continuous rated mode, the torque up control can be performed based on the front and rear driving force distribution by the above-mentioned method for the motor to which the maximum rated mode is allowed.

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 motor Also controls to drop from the maximum rated mode to the continuous rated mode. Then, for the other motor, torque is increased within a range that does not interfere with steering stability. This makes it possible to suppress deterioration of the motor beyond the allowable range of the maximum rated mode, secure driving force without causing a large change in torque distribution in the front and rear, and maintain steering stability of the vehicle 500. Become.

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 these 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 (14)

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.
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 equipped 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 when the operation of at least one of the first motor and the second motor is switched from the first mode to the second mode. After switching the operation of the motor and the other of the second motor from the first mode to the second mode, the other of the first motor and the second motor is driven based on the driving force distribution of the front wheels and the rear wheels. A vehicle control device characterized by controlling force. After switching the operation of the other of the first motor and the second motor from the first mode to the second mode, the other of the first motor and the second motor is driven based on the stability factor of the vehicle. The vehicle control device according to claim 1, wherein the force is controlled. The vehicle according to claim 2, wherein the driving force of the first motor and the other of 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. After switching the operation of the other of the first motor and the second motor from the first mode to the second mode, the driving force of the other of the first motor and the second motor is based on the side slip angular velocity of the vehicle. The vehicle control device according to claim 1, wherein the vehicle is controlled. The vehicle control device according to claim 4, wherein the driving force of the other of the first motor and the second motor is controlled based on the degree of deviation and the polarity of the side slip angular velocity and the yaw rate of the vehicle. After switching the operation of the other of the first motor and the second motor from the first mode to the second mode, the driving force of the other of the first motor and the second motor is applied based on the yaw rate of the vehicle. The vehicle control device according to claim 1, wherein the vehicle is controlled. The vehicle control device according to claim 6, wherein the driving force of the other 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. After switching the operation of the other of the first motor and the second motor from the first mode to the second mode, the first motor and the said so that the driving force distribution between the front wheels and the rear wheels is within a predetermined range. The vehicle control device according to claim 1, wherein the other driving force of the second motor is controlled. The vehicle control device according to claim 8, 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 first motor control unit is characterized in that, when the operating state of the first motor is overloaded, the operation of the first motor is switched from the first mode to the second mode. A vehicle control device as described in any of 9. The second motor control unit is characterized in that, when the operating state of the second motor is overloaded, the operation of the second motor is switched from the first mode to the second mode. A vehicle control device as described in any of 9. The invention according to any one of claims 1 to 11, 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 is the torque whose duration is not limited when the first motor or the second motor is operated at the continuous rated torque, according to any one of claims 1 to 12. 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.
A first mode in which when at least 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. To 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.
When the other of the first motor and the second motor is also operated in the first mode in which the maximum rated torque that can be generated is the upper limit, the operation is performed with the continuous rated torque lower than the maximum rated torque as the upper limit. And the step to switch to the second mode
A step of controlling the driving force of 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.

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