JP2005204436A - Drive force control device of wheel independently driven type electric vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make the protection of a motor compatible with the stability of traveling, by preventing the traveling from being unstable due to a change of the yaw rate behavior of a vehicle, when correcting an output of the motor to a reduction side that is estimated, such that a seizure-preventing temperature of the motor exceeded an allowable temperature range, in an electric vehicle of a wheel independently driven type, whose wheels are driven by the individual motors. <P>SOLUTION: A controller 5 reads motor temperature, detected by using signals of temperature sensors 6FL, 6FR, 6RL and 6RR installed at the driving motors 3FL, 3FR, 3RL and 3RR, and estimates the motor temperature after the detection. When the controller estimates that the left-side motor 3FL in the vehicle width direction is out of the allowable temperature range, the controller narrows down an output of the motor 3FL, and corrects the target driving force of a wheel 2FL to decrease by an amount -α. The controller then simultaneously increase an output of the remaining motor 3RL, corrects the target driving force of a wheel 2RL to increase by an amount +α, makes the total of drive forces at the left side in the vehicle width direction same as the one before the correction, and makes the sum of the drive forces of the wheels 2FL, 2FR, 2RL and 2RR the same as the one before the correction. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a driving force control of a wheel independent driving type electric vehicle having a safety function for reducing the driving force of a motor for driving wheels and preventing the motor from being burned.

Conventionally, for example, the invention disclosed in Patent Document 1 is known as a control invention in a case where a wheel independent drive type vehicle in which wheels are independently driven by individual drive motors and the drive motor becomes abnormal and cannot be driven. It has been.
JP-A-8-168112

  In the driving force control device described in Patent Document 1, when turning inner wheels in the turning direction out of the driving sources individually provided on the left and right sides cannot be driven during turning, the driving force is supplied from the left and right driving sources. When the outer wheel in the turning direction cannot be driven, the supply of driving force from the driving source of the outer wheel is stopped instantaneously, and the driving force of the inner ring is gradually decreased to stop the vehicle. It is intended to prevent sudden changes in behavior and thereby improve running stability and safety.

However, the conventional driving force control apparatus has the following problems. That is, in the control of Patent Document 1 for stopping the supply of driving force, although the unstable running of the vehicle caused by the sudden behavior change of the vehicle can be suppressed, the behavior change of the vehicle itself cannot be prevented. Still remains.
For this reason, the yaw rate behavior that is the actual turning traveling state of the vehicle corresponding to the driver's steering operation cannot be maintained, and the straight-running stability before turning incapable of driving, the turning radius, and the like change.
In addition, the total driving force before the driving becomes impossible cannot be maintained, and the vehicle cannot travel in an acceleration state corresponding to the driver's accelerator operation.

The present invention monitors the temperature of the motor that drives the wheel, and if it is estimated that the motor temperature rises beyond an allowable temperature range that does not cause seizure, the driving force of the wheel that is driven by this motor. The first object is to protect the motor by correcting the motor to a lower side than during normal control.
Then, a new problem that arises by correcting the wheel driving force to be smaller than that during normal control, that is, a change in the driving force distribution, a new yaw moment is generated in the vehicle, and the yaw rate behavior changes. A second object is to solve the problem and maintain the yaw rate behavior during normal control as well as during the reduction correction for motor protection.

For this purpose, the driving force control device according to the invention is as described in claim 1,
In a driving force control device that is used in a wheel independent drive type electric vehicle that independently drives wheels by individual motors and individually controls the driving force of the wheels,
Means for detecting the temperature of the motor, and temperature estimating means for estimating the detected motor temperature based on the detected motor temperature,
When the estimated motor temperature exceeds an allowable temperature range that is a temperature range that does not cause problems with the motor, the driving force of the wheel driven by the motor that exceeds the allowable temperature range is corrected to the decreasing side.

  In addition, the driving force of the remaining wheels is corrected so as to maintain the yaw moment of the vehicle when the above correction is not performed.

According to the driving force control apparatus of the present invention, it is possible to reduce the output of the motor that is estimated to exceed the allowable temperature range, and to prevent burn-in. And even if the driving force distribution of the wheels changes because of this, by correcting the output of the remaining motor so as to maintain the yaw moment that was generated in the vehicle before correcting to the decrease side Even during the correction, the yaw moment generated in the vehicle does not change, and it is possible to maintain the yaw rate behavior that is the actual turning traveling of the vehicle with respect to the steering operation of the driver before the correction.
Therefore, even when the correction is performed to protect the motor during the straight traveling, the yaw moment is prevented from being generated and the straight traveling performance is not impaired.
Further, even when the correction is performed to protect the motor during turning, it is possible to prevent the yaw rate behavior from changing and maintain the running characteristics during turning.

Hereinafter, embodiments of the present invention will be described in detail based on examples shown in the drawings.
FIG. 1 is a plan view showing a main part of a four-wheel independent drive type electric vehicle equipped with a drive force control device according to an embodiment of the present invention, together with its drive system.
The electric vehicle 1 has four wheels, a left front wheel 2FL, a right front wheel 2FR, a left rear wheel 2RL, and a right rear wheel 2RR. These wheels 2FL, 2FR, 2RL, and 2RR are drive shafts 9FL, 9FR, 9RL, and 9RR, respectively. The motors 3FL, 3FR, 3RL, and 3RR, which are individual drive sources, are connected via the. Thus, the motors 3FL, 3FR, 3RL, and 3RR can drive the electric vehicle 1 by individually driving the wheels 2FL, 2FR, 2RL, and 2RR.

Motors 3FL, 3FR, 3RL, 3RR are connected to controller 5 via power cables 4FL, 4FR, 4RL, 4RR. The controller 5 calculates the target driving force of the wheels 2FL, 2FR, 2RL, 2RR and supplies the electric power necessary for realizing the target driving force to the motors 3FL, 3FR, 3RL, 3RR. The controller 5 has temperature sensors 6FL, 6FR, 6RL, which detect the temperatures of the motors 3FL, 3FR, 3RL, 3RR, respectively, so that the controller 5 can obtain the target driving force of each wheel and supply necessary power. The signal from 6RR,
A signal from the yaw rate sensor 7 that detects the yaw rate behavior of the electric vehicle 1 and the electric power from the battery 8 are input.

The controller 5 basically calculates the target driving force of each wheel based on the accelerator opening and the vehicle speed, and supplies electric power to the motor to realize these target driving forces, but the detected motors 3FL, 3FR, 3RL When estimating that the motor temperature exceeds a predetermined allowable temperature range from the temperature of 3RR and the rate of increase of these motor temperatures per unit time, the power supply to the motor estimated to exceed the The driving force of the motor is corrected to the decreasing side, and the amount of heat generated by the motor is reduced to prevent the motor from being burned.
In this way, when the driving force of the wheel is decreased and corrected, the electric vehicle 1 cannot realize acceleration traveling according to the accelerator opening input by the driver, and the driver feels uncomfortable. Further, when only the driving force of one of the left and right wheels is corrected to decrease, a new yaw moment is generated in the electric vehicle 1 and the yaw rate behavior changes, so that the vehicle travels straight or turns according to the steering operation of the driver. It becomes impossible to run.

  Therefore, in this embodiment, the controller 5 normally calculates the target driving force of each wheel based on the accelerator opening and the vehicle speed, and controls the outputs of the motors 3FL, 3FR, 3RL, 3RR so as to realize these target driving forces. In addition to the above control, the control program shown in the flowchart in FIG. 2 is repeatedly executed to correct the target driving force of the wheels related to the remaining motors so that the above problem does not occur.

  First, in step S1, signals from the temperature sensors 6FL, 6FR, 6RL, 6RR are read, and the temperatures of the motors 3FL, 3FR, 3RL, 3RR are detected.

In the next step S2, the recommended temperature range of the motor temperature, which is an ideal temperature range for driving and rotating the motor, is referred to and any one of the detected motor temperatures of the motors 3FL, 3FR, 3RL, 3RR is detected. Determine whether one or more of them exceed the recommended temperature range. The recommended temperature range is stored in the controller 5 in advance.
If any motor temperature does not exceed the recommended temperature range (No), the detected motor temperature is sufficiently lower than the upper limit value of the allowable temperature range, and there is no possibility that the motor will be burned. The four-wheel running is continued in accordance with the normal control that is realized without correcting the target driving force of this, and this control is terminated.
The allowable temperature range of the motor temperature refers to a range in which the motor can be driven and rotated so as not to cause problems such as seizure. The upper limit value of the allowable temperature range is higher than the upper limit value of the recommended temperature range. .

On the other hand, if at least one motor temperature exceeds the recommended temperature range in step S2 (Yes), the process proceeds to step S4, and the amount of change in the motor temperature at time Δt, for example, the motor detected when the previous flowchart was executed. A motor temperature change rate is calculated by dividing the amount of change between the temperature and the motor temperature detected at the time of execution of this flowchart by the flowchart execution time. Whether or not the allowable temperature range is exceeded when the four-wheel traveling is continued according to the normal control for realizing the calculated target driving force of each wheel based on the calculated motor temperature change rate and the most recently detected motor temperature. I guess.
If it is estimated that both the front motors 3FL and 3FR and the rear motors 3RL and 3RR exceed the allowable temperature range (Yes), the process proceeds to step S5, and the target driving force of all the wheels is corrected to the decreasing side at a uniform rate. Then, the four-wheel drive is continued so as to realize the driving force corrected for decrease, and this control is finished.
FIG. 3 is a plan view schematically showing an example of the correction of the target driving force executed in step S5. The outputs of all the motors 3FL, 3FR, 3RL and 3RR are reduced and corrected at the same rate.

  On the other hand, when it is estimated in step S4 that any one of the front motors 3FL and 3FR or the rear motors 3RL and 3RR exceeds the allowable temperature range (No), the process proceeds to step S6.

In step S6, it is determined whether the motor estimated to exceed the allowable temperature range is the front wheel 2FL, 2FR drive motor 3FL, 3FR or the rear wheel 2RL, 2RR drive motor 3RL, 3RR.
If it is estimated that either one or both of the front wheel motors 3FL and 3FR exceed the allowable temperature range (Yes), the process proceeds to step S7, and the target driving force of the front wheels 2FL and 2FR related to the corresponding front wheel motor is predetermined. The output of the corresponding motor is quickly decreased so that the value α is corrected to the decreasing side.

In the following step S8, the maximum driving force of the rear wheels 2RL and 2RR is first obtained based on the maximum output of the rear wheel motors 3RL and 3RR, the difference between the maximum driving force and the target driving force is calculated, and the rear wheels 2RL and 2RR are It is determined whether or not the driving force can be increased by a predetermined value α.
If it is determined that the vehicle can be increased (Yes), the process proceeds to step S9, and the driving force of the rear wheels 2RL and 2RR on the same side as the decrease corrected in step S7 of the left and right wheels is increased by a predetermined value α. Correct to 4 and run 4WD.
In other words, the vehicle continues traveling in a state where the total driving force of the wheels 2FL, 2FR, 2RL, and 2RR is maintained without correction.
FIG. 4 is a plan view schematically showing an example of the correction of the target driving force executed in steps S7 and S9. For example, when the output of the front wheel motor 3FL is corrected to decrease in step S7, the output of the rear wheel motor 3RL is corrected to increase in step S9.

  When correcting both the left and right front wheels 2FL and 2FR to the decreasing side in step S7, the target driving force of the left and right rear wheels 2RL and 2RR is corrected to the increasing side in step S9.

On the other hand, if it is determined in step S8 that it is impossible to increase (No), the process proceeds to step S10, and the rear wheels 2RL and 2RR on the opposite side of the left wheel and right wheel on the side corrected for reduction in step S7 are detected. The driving force is corrected to the decreasing side by a predetermined value α, and the four-wheel drive is continued.
In other words, the vehicle continues running with the total driving force of the wheels 2FL, 2FR, 2RL, and 2RR being smaller than that when no correction is made.
FIG. 5 is a plan view schematically showing an example of the correction of the target driving force executed in steps S7 and S10. For example, when the output of the front wheel motor 3FL is corrected to decrease in step S7, the output of the rear wheel motor 3RR is corrected to decrease in step S10.

  On the other hand, when it is estimated in step S6 that one or both of the rear wheel motors 3RL and 3RR exceed the allowable temperature range (No), the process proceeds to step S11, and the rear wheel 2RL related to the corresponding rear wheel motor is obtained. , 2RR is quickly reduced so that the target driving force of 2RR is corrected by a predetermined value α.

In the subsequent step S12, the maximum driving force of the front wheels 2FL, 2FR is calculated based on the maximum output of the front wheel motors 3FL, 3FR, and it is determined whether or not the driving force of the front wheels 2FL, 2FR can be increased by a predetermined value α.
If it is determined that it can be increased (Yes), the process proceeds to step S13, and the driving force of the front wheels 2FL, 2FR on the same side as the side on which the output is reduced and corrected in step S11 among the left and right wheels is set to a predetermined value. Increase correction by α and continue to drive 4WD.
In other words, the vehicle continues traveling in a state where the total driving force of the wheels 2FL, 2FR, 2RL, and 2RR is maintained without correction.

  If both the left and right rear wheels 2RL and 2RR are corrected to decrease in step S11, the target driving force for the left and right front wheels 2FL and 2FR is corrected to increase in step S13.

On the other hand, if it is determined in step S12 that the vehicle cannot be increased (No), the process proceeds to step S14, and the front wheels 2FL and 2FR on the opposite side of the left wheel and the right wheel on the side subjected to the reduction correction in step S11. The driving force is corrected to the decreasing side by a predetermined value α, and the four-wheel drive is continued.
In other words, the vehicle continues running with the total driving force of the wheels 2FL, 2FR, 2RL, and 2RR being smaller than that when no correction is made.

After executing the driving force correction control of the wheels 2FL, 2FR, 2RL, 2RR in the above step S9, S10, S13 or S14, the process proceeds to step S15, and the signals from the temperature sensors 6FL, 6FR, 6RL, 6RR are read and the motor is read. Detects temperature of 3FL, 3FR, 3RL, 3RR.
In the next step S16, it is determined whether or not the detected motor temperature is equal to or lower than the upper limit value of the recommended temperature range. If any motor temperature is equal to or lower than the upper limit value of the recommended temperature range (Yes), the process proceeds to step S17, and the motor 3FL is set so as to match the target driving force when the driving force of the wheels 2FL, 2FR, 2RL, 2RR is not corrected. , 3FR, 3RL, 3RR output correction is performed gradually, and this control ends.
On the other hand, if the recommended temperature range is exceeded in step S16 (No), step S17 is skipped and the present control is terminated, and the correction of the target driving force is continued in steps S7 to S14 of the repetitive control.

  FIG. 6 is a time chart showing the time change of the detected temperatures of the motors 3FL, 3FR, 3RL, and 3RR and the time change of the output of the motor whose output is corrected to decrease to prevent burn-in. The drive control of the present embodiment will be described based on this time chart. When one of the four motor temperatures exceeds the recommended motor temperature range at time t1 (Yes in step S2), after time Δt from time t1. The rate of increase in the motor temperature is estimated from the amount of change in the motor temperature up to the point indicated by the one-dot chain line in the figure. As a result, since the estimated value of the motor temperature exceeds the upper limit value of the motor allowable temperature range (No in step S4), the output of the motor is indicated by a thick dotted line in a short time D1 from time t2 to time t3 thereafter. As described above, the correction is made to be smaller than the normal control (steps S7 and S11).

The output of the motor continues to be corrected to decrease after time t3, but after a while, when the motor temperature falls below the upper limit value of the recommended motor temperature range at time t4 (in step S16 above) Yes), over the long time D2 from time t4 to time t5, the motor output is returned to the value without correction (output during normal control) as shown by the thick dotted line, and the wheels 2FL, 2FR , 2RL and 2RR are adjusted to the target driving force when correction is not performed.
In FIG. 6, the description of the correction of the target driving force of the remaining motor is omitted. However, among the remaining motors, the correction of the target driving force is also performed between time t4 and time t5. Gradually return to the value when it is not used (output during normal control).
As described above, when the target driving force of the wheel is reduced and corrected for reduction, the required time D1 is short, and when the target driving force of the wheel is restored, the required time D2 is long. Assume that D1 <D2.

By the way, in the present embodiment, for example, as shown in FIG. 7, when it is estimated that the motor temperature of the motor 3FL exceeds a predetermined allowable temperature range, the controller 5 decreases the output of the motor 3FL in step S7. In addition to correction, the outputs of the remaining motors 3FR, 3RL, and 3RR are normally controlled or corrected for increase or decrease in steps S8 to S10, and the total driving force of the left wheels 2FL and 2RL at the time of correction and at the time of correction are corrected. The ratio of the total driving force of the right wheels 2FR and 2RR to maintain the ratio between the total driving force of the left wheels 2FL and 2RL without correction and the total driving force of the right wheels 2FR and 2RR without correction In addition, the target driving force of the remaining wheels 2FR, 2RL, 2RR is corrected.
Accordingly, the yaw moment generated in the vehicle body 1 immediately after the correction can be made the same as the yaw moment generated in the vehicle body 1 immediately before the correction, and it is possible to prevent the yaw rate from rapidly changing immediately after the correction. .
Furthermore, the yaw rate behavior of the vehicle body 1 being corrected can be matched with the yaw rate behavior of the vehicle body 1 when no correction is made, and the running performance of the vehicle does not change as in the conventional case. Therefore, it is possible to both reduce and correct the motor output to prevent burn-in and maintain the yaw rate behavior of the vehicle, and the straight running stability with respect to the steering operation of the driving vehicle and the running characteristics during turning It is possible to prevent the change.
Further, as in the prior art, it is possible to continue self-running without stopping all the driving forces of the wheels and continuing running.

  In addition, when performing increase / decrease correction of predetermined value (alpha) about the target drive force of the remaining wheel in said step S7-S14, based on the signal from the yaw rate sensor 7, the said target drive force correction | amendment is finely adjusted by feedback control. Thus, complete prevention of the change in the yaw rate behavior of the vehicle body 1 can be achieved.

In this embodiment, the four-wheel drive running is maintained as shown in FIGS. 8A, 8B, 8C, etc. while reducing and correcting the motor output to prevent burn-in. However, the present invention is not limited to the all-wheel drive mode (4WD), and the front wheel drive mode (FF) for driving the front wheels 2FL, 2FR as shown in FIGS. ), (B) etc., the rear wheel drive mode (RR) for driving the rear wheels 2RL, 2RR, the right front wheel 2FR and the left rear wheel 2RL as shown in FIGS. 11 (a), 11 (b), etc. Or the diagonal wheel drive mode for driving the left front wheel 2FL and the right rear wheel 2RR, which is not shown, is set in the controller 5,
When correcting the motor output to prevent burn-in, first, the all-wheel drive mode is executed. If the all-wheel drive mode cannot be executed due to travel settings or the failure of the motors 3FL, 3FR, 3RL, 3RR, etc. The second is to execute the front wheel drive mode, the third is to execute the rear wheel drive mode, and the fourth is to execute the diagonal wheel drive mode, so that the yaw rate behavior of the vehicle body 1 is maintained. In addition, the movement characteristics of the vehicle can be set to the stable side, and the driving safety can be improved.

In addition, the all-wheel drive mode (4WD) can optimally determine the driving force distribution of the wheels 2FL, 2FR, 2RL, 2RR according to the weight distribution of the vehicle body 1 and so on. Can be set on the safe side. Further, in the front wheel drive mode (FF), the turning characteristic is understeer, so that the vehicle body is hard to spin and the movement characteristic of the vehicle can be set to the safe side. Further, in the rear wheel drive mode (RR), the turning characteristic is oversteer.
Therefore, the priority order of the drive modes to be executed is as follows: first, the all-wheel drive mode (4WD) is selected, the second is the front wheel drive mode (FF), and the third is the rear wheel drive mode (RR). And fourth, setting to select the diagonal wheel drive mode.

  In this embodiment, all-wheel drive mode (4WD) is executed by four motors 3FL, 3FR, 3RL, 3RR, but only two motors 3FL, 3FR are mounted in addition to this embodiment, According to the present invention, even a vehicle that executes only the front wheel drive mode (FF), or a vehicle that mounts only the two motors 3RL and 3RR and executes only the rear wheel drive mode (RR). Of course, it is possible to maintain the yaw rate behavior of the vehicle body.

In particular, in this embodiment, as shown in FIG. 4, when the output of the motor 3FL is corrected to the decrease side in step S7, the output of the remaining motor 3RL is corrected to the increase side in step S9.
That is, when step S9 is selected, the target driving force of the left rear wheel 2RL on the same left side as the left front wheel 2FL corrected by -α is corrected by + α. Therefore, the target drive of the remaining wheels 2FR, 2RL, 2RR is maintained so that the total driving force of the corrected wheels 2FL, 2RL, 2FR, 2RR maintains the total driving force of the corrected wheels 2FL, 2RL, 2FR, 2RR. The force can be corrected, the yaw rate behavior can be maintained as well as the longitudinal acceleration, and the motor burn-in can be prevented without deteriorating the running characteristics of the vehicle.

Alternatively, when there is no allowance for the maximum output of the rear wheel motor 3RL and step S10 is selected instead of step S9, the right side that is diagonally positioned with respect to the left front wheel 2FL and the vehicle body 1 that have been corrected by -α. The target driving force of the rear wheel 2RR is corrected by -α.
Therefore, the total driving force of the corrected wheels 2FL, 2RL, 2FR, 2RR cannot maintain the total driving force of the corrected wheels 2FL, 2RL, 2FR, 2RR, and although the longitudinal acceleration decreases, the corrected driving force The ratio between the total driving force of the left wheels 2FL and 2RL and the corrected driving force of the right wheels 2FR and 2RR is the total driving force of the left wheels 2FL and 2RL before correction and the driving of the right wheels 2FR and 2RR before correction. It can be the same as the ratio to the total force.
As a result, the yaw moment generated in the vehicle body 1 can be prevented from changing, the yaw rate behavior of the vehicle body 1 can be maintained, and motor seizure can be prevented while maintaining the turning characteristics of the vehicle 1. Can do.
In particular, when executing the front wheel drive mode (FF), the rear wheel drive mode (RR), and the diagonal wheel drive mode, the wheels 2FL, 2RL, 2FR, 2RR before correction are different from the all wheel drive mode (4WD). Therefore, the yaw rate behavior of the vehicle body 1 can be maintained by the main control executed in step S10.

  In this embodiment, in order to prevent the burn-in of all the motors 3FL, 3FR, 3RL, 3RR, the output of all the motors 3FL, 3FR, 3RL, 3RR is uniformly corrected to the decreasing side in step S5. Therefore, although the longitudinal acceleration decreases, the yaw rate behavior of the vehicle body 1 can be maintained, and the seizure of some motors can be prevented while maintaining the turning characteristics of the vehicle 1.

Further, the controller 5 changes the time between the motor temperature of each motor 3FL, 3FR, 3RL, 3RR and the motor temperature detected before the time Δt based on the signals from the temperature sensors 6FL, 6FR, 6RL, 6RR. From the above, it is estimated whether the motor temperature exceeds the allowable range.
The motor 3FL, 3FR, 3RL, 3RR can be prevented from being burned without overheating. Therefore, the durability of the motors 3FL, 3FR, 3RL, 3RR can be expected to be improved.

Further, in the present embodiment, when the motor temperature whose output has been corrected to decrease to prevent burn-in has fallen to the recommended temperature range, in step S16, as shown from time t4 to time t5 in FIG. The corrected motor output is gradually returned to the output during normal control.
Therefore, the change in running characteristics of the electric vehicle 1 becomes gradual, and the driver does not feel uncomfortable.

  The present invention can be applied to all vehicles that drive wheels using an electric motor, and of course includes a fuel cell and the like as a power source of the motor.

It is a principal part top view which shows the drive system of the electric vehicle of a four-wheel independent drive system provided with the drive force control apparatus of the wheel independent drive type vehicle which becomes this invention. It is a flowchart which shows the control program which the same driving force control apparatus performs. It is a top view which shows the arrangement | positioning relationship of these motors and wheels in the case of reducing the output of all the motors of the same electric vehicle uniformly for prevention of burn-in. FIG. 4 is a plan view showing the positional relationship between these motors and wheels when the output of the remaining motors is increased and corrected when the output of the left front motor of the electric vehicle is decreased to prevent burn-in. FIG. 5 is a plan view showing the positional relationship between these motors and wheels when the output of the remaining motors is corrected to decrease when the output of the left front motor of the electric vehicle is decreased to prevent burn-in. It is a time chart which compares the time change of each detected motor temperature, the estimated motor temperature, and the time change of the output of the motor by which the output is corrected to decrease to prevent burn-in. FIG. 4 is a plan view showing the positional relationship between these motors and wheels when correcting the outputs of the remaining motors when the output of the motors of the electric vehicle is reduced to prevent burn-in. A plan view showing the positional relationship of these motors and wheels when correcting the output of the remaining motors in all-wheel drive mode (4WD) when reducing the output of the motor of the electric vehicle to prevent burn-in. Yes, (a) normal control of the motor output of the left and right front wheels, and correction of decrease in the motor output of the left and right rear wheels, (b) correction of decrease of the motor output of the left and right front wheels, In the case of normal control, (c) shows a case where all motor outputs are corrected to decrease. FIG. 3 is a plan view showing the positional relationship between these motors and wheels when correcting the output of the remaining motors in the front wheel drive mode (FF) when reducing the output of the motors of the electric vehicle to prevent burn-in. Yes, when (a) controls the motor output of the left and right front wheels normally and sets the motor output of the left and right rear wheels to 0, (b) corrects the motor output of the left and right front wheels to decrease, The case where 0 is set is shown. FIG. 3 is a plan view showing the positional relationship between these motors and wheels when correcting the output of the remaining motors in the rear wheel drive mode (RR) when reducing the output of the motor of the electric vehicle to prevent burn-in. Yes, (a) Sets the motor output of the left and right front wheels to 0 and controls the motor output of the left and right rear wheels normally. (B) Sets the motor output of the left and right front wheels to 0 and corrects the motor output of the left and right rear wheels to decrease. Indicates when to do. In the case of reducing the output of the motor of the electric vehicle to prevent burn-in, when correcting the output of the remaining motor in the diagonal wheel drive mode, it is a plan view showing the positional relationship of these motors and wheels, (A) The case where the left front and right rear motor outputs are set to 0 and the right front and left rear motor outputs are normally controlled. (B) The left front and right rear motor outputs are set to 0. The case where the motor output at the left rear is corrected to decrease is shown.

Explanation of symbols

1 Electric car (body)
2FL Left front wheel 2FR Right front wheel 2RL Left rear wheel 2RR Right rear wheel 3FL Left front wheel drive motor 3FR Right front wheel drive motor 3RL Left rear wheel drive motor 3RR Right rear wheel drive motor 5 Controller
6FL Temperature sensor for left front wheel drive motor
6FR Temperature sensor for right front wheel drive motor
6RL Temperature sensor for left rear wheel drive motor
6RR Temperature sensor for right rear wheel drive motor 7 Yaw rate sensor 8 Battery

Claims (8)

In a driving force control device that is used in a wheel independent drive type electric vehicle that independently drives wheels by individual motors and individually controls the driving force of the wheels,
Means for detecting the temperature of the motor, and temperature estimating means for estimating the detected motor temperature based on the detected motor temperature,
When the estimated motor temperature exceeds the allowable temperature range that does not cause a thermal failure in the motor, the driving force of the wheel driven by the motor exceeding the allowable temperature range is corrected to the decrease side, and the correction is made. A driving force control device for a wheel independent drive type electric vehicle, wherein the driving force of the remaining wheels is corrected so as to maintain the yaw moment of the vehicle when not. The drive mode selection means according to claim 1, further comprising a drive mode selection means for setting a plurality of drive modes for driving at least one of the wheels and selecting and executing one of the drive modes. In the driving force control device,
A drive power control device for a wheel independent drive type electric vehicle, wherein priority is set for the plurality of drive modes, and the drive mode selection means selects and executes a drive mode according to the priority when the correction is performed. . The driving force control device according to claim 2, wherein the driving force control device is used for a wheel independent drive type electric vehicle including the wheels on the front, rear, left and right sides of the vehicle body.
The plurality of drive modes include an all-wheel drive mode for driving all wheels, a front wheel drive mode for driving front wheels, a rear wheel drive mode for driving rear wheels, a right front wheel and a left rear wheel. It is a diagonal wheel drive mode that drives or drives the left front wheel and the right rear wheel,
The priority order includes priority in the order of first in all-wheel drive mode, second in front wheel drive mode, third in rear wheel drive mode, and fourth in diagonal wheel drive mode. Driving force control device for driving electric vehicle. The driving force control apparatus according to any one of claims 1 to 3,
The driving force of the wheel independent drive type electric vehicle is characterized in that the driving force of the remaining wheels is corrected so that the total driving force of the wheel at the time of correction maintains the total driving force of the wheel without correction. Control device. The driving force control device according to claim 4, wherein the wheels are provided on the left side and the right side of the vehicle body, respectively.
Means for calculating the maximum driving force of the wheel, and if the total driving force of the wheel cannot be maintained when the correction is not performed because the calculated maximum driving force is insufficient, among the remaining wheels arranged on the left and right A driving force control device for a wheel independent drive type electric vehicle, wherein the driving force of a wheel located on the side opposite to the side where the wheel driven by the motor exceeding the allowable temperature range is located is corrected to a decreasing side. The driving force control apparatus according to any one of claims 1 to 3,
When the estimated motor temperature of all the motors exceeds the allowable temperature range, the driving force of the wheel driven by the motor is uniformly corrected to the decreasing side. Control device. The driving force control apparatus according to any one of claims 1 to 6,
The said temperature estimation means estimates the motor temperature after a detection from the time change of the motor temperature each detected at several different time, The driving force control apparatus of the wheel independent drive type electric vehicle characterized by the above-mentioned. In the driving force control device according to any one of claims 1 to 7,
When the detected motor temperature is reduced to a recommended temperature range that is appropriate for driving rotation of the motor during the correction, the corrected wheel driving force is gradually returned to the driving force without correction. A driving force control device for a wheel independent drive type electric vehicle characterized by the above.

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