JP2005119647A - Driving force control device for wheel independent drive system vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent behavior change, enable travelling and ensure safety, when drive of part of wheels of an independent drive system vehicle becomes impossible during travelling. <P>SOLUTION: When recognizing drive incapability of the wheels 2FL, 2FR, 2RL, 2RR, a control unit 6 determines whether the vehicle 1 performs straight traveling or turning traveling, and whether vehicle speed VSP is creeping speed, low speed or high speed, and classifies a traveling state of the vehicle 1. In accordance with this classification, target driving force of other normal wheels is corrected, and a driving force command is outputted to motor controllers 5FL, 5FR, 5RL, 5RR. The correction method is performed such that a ratio of a total of driving force of left side wheels to a total of driving force of right side wheels during normal time becomes equal to that during drive incapability. As a rule, the correction method is performed such that a total of the target driving force of the normal wheels after correction becomes equal to driving force corresponding to an accelerator opening APO. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a wheel independent drive type vehicle such as a wheel independent drive type electric vehicle in which the wheels are independently driven by a drive source such as an individual motor. The present invention relates to a technique that enables a traveling state before a failure to be maintained even when a wheel is incapable of being driven.

As a control invention for a case where a drive system of a wheel independent drive type vehicle has failed, there has been known one as described in Patent Document 1, for example.
JP-A-8-168112

  In the driving force control device described in Patent Document 1, when one of the driving sources individually provided on the left and right sides cannot be driven during turning, the driving force of the other driving source is instantaneously generated. Alternatively, the vehicle is stopped while gradually decreasing to prevent sudden changes in the behavior of the vehicle, thereby improving running stability and safety.

However, the conventional driving force control apparatus has the following problems. That is, only stopping the driving force according to the control of Patent Document 1 can suppress the unstable traveling of the vehicle caused by the sudden behavior change of the vehicle, but cannot prevent the behavior change of the vehicle itself.
For this reason, it is possible to maintain a traveling state including a straight traveling before turning into a drive-disabled state and a turning traveling such as a turning radius and a yaw rate behavior, that is, a traveling state including the traveling direction and driving force of the vehicle. It cannot be done and the driving performance is not lowered.
Moreover, since all the driving forces of the wheels are stopped, it is impossible to continue traveling, and it is impossible to deny that it is inconvenient such that self-propulsion to a repairable location becomes impossible.

  The present invention realizes the traveling state of the vehicle corresponding to the driving state by using other normal wheels when some of the wheels become unable to drive during traveling, The purpose is to allow the vehicle to continue running according to the driving state.

For this purpose, the vehicle according to the invention is as claimed in claim 1,
In a driving force control device that is used in a wheel independent driving type vehicle that independently drives a wheel with an individual driving source, and individually controls the driving force of the wheel,
Driving state detecting means for detecting the driving state of the wheel independent drive vehicle;
Drive source failure detection means for detecting the drive source failure,
While the failure of one of the drive sources is detected by the means, the running state of the vehicle using another normal drive source is changed to a running state corresponding to the driving state detected by the driving state detecting means. As a result, the driving force is controlled by a normal driving source.

According to such a configuration of the present invention, when some of the wheels become unable to drive during traveling, the driving force control inherent in the detection of the failure using other normal wheels causes the vehicle corresponding to the driving state. To realize the running state,
It is possible to avoid a decrease in driving performance due to the failure and to prevent the running stability and safety from being impaired.
In addition, since other normal wheels can be driven under the above driving force control and the vehicle can continue to travel, the vehicle can travel to its destination and is beneficial to the driver.

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 motors 3FL that are individual drive sources. , 3FR, 3RL, 3RR, and the driving force of wheels 2FL, 2FR, 2RL, 2RR can be individually controlled via these motors.

A battery 4 is provided as a common power source for the motors 3FL, 3FR, 3RL, 3RR, and the battery 4 is connected to the motors 3FL, 3FR, 3RL, 3RR via the motor controller 5FL, 5FR, 5RL, 5RR as shown in FIG. Connect as shown by the bold line.
The motor controllers 5FL, 5FR, 5RL, and 5RR receive driving force commands F1, F2, F3, and F4 from the control unit 6, respectively, and power corresponding to these commands is supplied from the battery 4 to the corresponding motors 3FL, 3FR, 3RL, The driving force of the motors 3FL, 3FR, 3RL, and 3RR (the driving force of the wheels 2FL, 2FR, 2RL, and 2RR) is made to coincide with the driving force commands F1, F2, F3, and F4, respectively.

The motors 3FL, 3FR, 3RL, 3RR are provided with individual incompetence detection sensors 7FL, 7FR, 7RL, 7RR. These sensors detect the inability to drive the motors 3FL, 3FR, 3RL, 3RR when they cannot be driven. Is output to the control unit 6.
Non-drive detection sensor 7FL, 7FR, 7RL, 7RR detection method of non-drive, for example, by monitoring the resistance value of the motor coil, if the resistance value becomes infinite, it is determined that the coil is disconnected, Determine.

The control unit 6 detects a signal from the steering angle sensor 9 that detects the steering angle θ of the steering wheel 8 and the vehicle speed VSP in addition to the signals from the motor drive impossibility detection sensors 7FL, 7FR, 7RL, and 7RR. A signal from the vehicle speed sensor 10 and a signal from the accelerator opening sensor 11 for detecting the accelerator pedal depression amount (accelerator opening) APO are input.
The output of the control unit 6 is further connected with an indicator 12 as an alarm device for appropriately warning that the motors 3FL, 3FR, 3RL, 3RR cannot be driven.

The control unit 6 basically calculates the target driving force F1, F2, F3, F4 based on the accelerator opening APO and the vehicle speed VSP, and uses these as driving force commands to control the motor controllers 5FL, 5FR, 5RL, Output to 5RR. Further, if necessary, the calculated target driving force is corrected so that the traveling direction of the vehicle based on the steering angle θ is suitably realized, and these corrected target driving forces F1, F2, F3, and F4 are set as driving force commands. Output as
When a signal indicating that one of the motors 3FL, 3FR, 3RL, 3RR has become incapable of driving is received from the motor inoperability detection sensors 7FL, 7FR, 7RL, 7RR, the target driving forces F1, F2, F3, F4 are It will be decided as described later.

The control unit 6 is as shown in FIG. 2 in terms of a functional block diagram, and each wheel drive source monitoring unit 21, turning / straight running determination unit 22, vehicle speed region determination unit 23, and abnormal drive source determination unit 24 and the driving force correction unit 25, and when it is detected that one or more of the wheels 2FL, 2FR, 2RL, and 2RR cannot be driven, the control program described in FIG. Based on the above, the target driving forces F1, F2, F3, and F4 are corrected, and the corrected target driving force commands are output to the controllers 5a, 5b, 5c, and 5d.
Each wheel drive source monitoring unit 21 monitors whether the motors 3FL, 3FR, 3RL, and 3RR cannot be driven. When it is recognized that the motors 3FL, 3FR, 3RL, and 3RR cannot be driven by signals from the motor drivability detection sensors 7FL, 7FR, 7RL, and 7RR, the drivability detection signal is output to the turning / straight advance determination unit 22. To do.
The turning / straight-ahead determination unit 22 refers to the steering angle θ input from the steering angle sensor 9 to determine whether the driving state of the vehicle is turning or traveling straight, and the determination result is the vehicle speed region determination unit 23. Output to.

  The vehicle speed area determination unit 23 determines whether the electric vehicle 1 is traveling at a low speed, a low speed, or a high speed based on the vehicle speed VSP detected by the vehicle speed sensor 10, and the determination result is an abnormal drive source determination unit 24. Output to. The abnormal drive source determination unit 24 determines the position of the motor that has become unable to drive among the motors 3FL, 3FR, 3RL, and 3RR, and outputs the determination result to the drive force correction unit 25. The driving force correction unit 25 corrects the normal driving target driving forces F1, F2, F3, and F4 calculated by another control program (not shown), and outputs the corrected target driving force commands to the motor controllers 5FL, 5FR, Output to 5RL, 5RR. At this time, it goes without saying that the target driving force of a motor that cannot be driven is not corrected, but the target driving force of a normal motor is corrected. The motor controllers 5FL, 5FR, 5RL, and 5RR control the motors 3FL, 3FR, 3RL, and 3RR to execute the corrected target driving force command.

FIG. 3 is a flowchart showing a driving force control program executed by the control unit 6 described in FIG. 2 in preparation for the inability to drive the motors 3FL, 3FR, 3RL, 3RR while the vehicle is running. This program is executed repeatedly at regular intervals.
In step S1, it is determined whether or not any one or more of motors 3FL, 3FR, 3RL, and 3RR cannot be driven. If all motors 3FL, 3FR, 3RL, 3RR are not driveable and are normal, this program ends. On the other hand, if any one or more of motors 3FL, 3FR, 3RL, and 3RR cannot be driven, it is determined that the vehicle cannot be driven, and in the next step S2, whether or not the vehicle is traveling straight is determined based on the steering angle θ. to decide. If the steering angle θ is within ± 5 °, it is determined that the vehicle is traveling straight, and the process proceeds to step S3. On the other hand, if the steering angle θ is other than ± 5 °, it is determined that the vehicle is turning, and the process proceeds to step S7.

  In step S3, it is determined whether the vehicle is traveling at a slow speed, traveling at a low speed, or traveling at a high speed based on the vehicle speed VSP. If the vehicle speed V is less than 10 km / h, it is determined that the vehicle speed is very low, and the process proceeds to step S4. If the vehicle speed V is 10 km / h or more and less than 60 km / h, it is determined that the vehicle speed is low and the process proceeds to step S5. If the vehicle speed V is 60 km / h or higher, it is determined that the vehicle speed is high, and the process proceeds to step S6. Here, the boundary between the low speed region and the high speed region was set to 60 km / h, which is a speed limit for general roads.

  In step S4, driving force control is performed when the vehicle travels at a slow speed. Specifically, the indicator 12 is activated to give a warning to the driver. Since the vehicle is traveling straight at a slow speed, even if there is a difference in driving force between the pair of left and right wheels 2FL and 2FR (or between 2RL and 2RR), the running stability will not be impaired. The driving force is not corrected. At this time, the driver is informed of the position of the motor (3FL, 3FR, 3RL, or 3RR) that cannot be driven.

  In step S5, driving force control is performed when the vehicle travels straight at a low speed. Specifically, the indicator 12 is activated to give a warning to the driver. Since the driving state is low speed and straight running, other normal motors (3FL, 2FL, 2RL) are adjusted so that the total driving force of the left wheels 2FL, 2RL is equal to the total driving force of the right wheels 2FR, 2RR. The target driving force of 3FR, 3RL, or 3RR) is corrected to maintain the straight running state. In addition, the target driving force of another normal motor (any of 3FL, 3FR, 3RL, or 3RR) is corrected to output the same driving force as before driving is disabled (during normal operation), and the accelerator is opened. Achieving the target driving force corresponding to the degree APO. Also, taking advantage of the characteristics of an electric motor with extremely good responsiveness, add a vibration component to the target driving force command to the motor controller 5FL, 5FR, 5RL, 5RR, and add it to any of the motors 3FL, 3FR, 3RL, 3RR. The driver is made aware of the impossibility of driving, and the cognition to the passenger is improved. The frequency of the vibration component is 5 to 10 Hz, which is less than the eigenvalue of the vehicle and does not adversely affect the running state, can easily transmit the vehicle body, and can feel close to the natural frequency of the human body. In order to distinguish the direction of the vibration component from the vehicle vertical vibration from the road surface, it is desirable to make the vehicle longitudinal vibration by driving force positive / negative control.

  In step S6, driving force control during high speed straight traveling is performed. Specifically, the indicator 12 is activated to give a warning to the driver. Since the driving state is high speed and straight running, other normal motors (3FL, 2FL, 2RL) are adjusted so that the total driving force of the left wheels 2FL, 2RL is equal to the total driving force of the right wheels 2FR, 2RR. The target driving force of 3FR, 3RL, or 3RR) is corrected to achieve a straight traveling state. In addition, in order to prevent deterioration in running stability, the driver is not recognized by adding vibration components. Instead, the target driving force of another normal motor (any of 3FL, 3FR, 3RL, or 3RR) using the gain is changed to the target driving force corresponding to the accelerator opening APO (the target in the normal state before driving becomes impossible). The driving force is corrected to be lower than the driving force), and the driver is made aware that the motor 3FL, 3FR, 3RL, 3RR has become unable to drive, and the acceleration performance is reduced to improve driving safety. Secure. Even if the driver inputs the same accelerator pedal depression amount (accelerator opening APO) as when all the drive motors are normal, the driver notices that the longitudinal acceleration of the vehicle is slow, so that the driver is unable to drive. It becomes possible to recognize.

  On the other hand, if it is determined in step S2 that the vehicle is turning, in the next step S7, it is determined whether the vehicle is traveling at a slow speed, traveling at a low speed, or traveling at a high speed based on the vehicle speed VSP. The determination method is the same as step S3 described above.

  In step S8, driving force control during slow turn is performed. Specifically, the indicator 12 is activated to give a warning to the driver. Since the driving state is turning at a slow speed and is more unstable than the straight running, the turning state corresponding to the driving state before the motor becomes unable to drive, that is, the driving state (steering angle θ) is realized. Therefore, the target of other normal motors (either 3FL, 3FR, 3RL, or 3RR) should be set so that the sum of the driving forces of the left wheels 2FL and 2RL matches the sum of the driving forces of the right wheels 2FR and 2RR. Correct the driving force. Then, the vibration component described in the above step S5 is added to the target driving force corresponding to the accelerator opening APO (the target driving force in a normal state before driving becomes impossible), and the motors 3FL, 3FR, 3RL, Sensefully recognize that one of the 3RRs has become unable to drive.

  In step S9, driving force control during low-speed turning is performed. Specifically, the indicator 12 is activated to give a warning to the driver. Since the driving state is turning at low speed, the total driving force of the left wheels 2FL, 2RL and the right wheels 2FR, 2RR of the right wheels 2FR, 2RR are required to realize turning driving corresponding to the driving state (steering angle θ). The target driving force of another normal motor (3FL, 3FR, 3RL, or 3RR) is corrected so that the total driving force is the same. Furthermore, in order to prevent deterioration in running stability, the driver is not recognized by adding vibration components. Instead, the target driving force is corrected using gain to be lower than the target driving force corresponding to the accelerator opening APO (normal target driving force before driving becomes impossible), and the motors 3FL, 3FR , 3RL, 3RR to make the driver aware that inability to drive, and to reduce the acceleration performance to ensure driving safety. Even if the driver inputs the same accelerator pedal depression amount (accelerator opening APO) as when all the drive motors are normal, the driver notices that the longitudinal acceleration of the vehicle is slow, so that the driver is unable to drive. It becomes possible to recognize.

  In step S10, driving force control during high-speed turning is performed. Specifically, since the vehicle is turning at a high speed, a warning is given to the driver without operating the indicator 12 in order to prevent the driving from becoming unstable due to an inadvertent driving operation by the driver. Absent. Since the driving state is turning at a high speed, in order to realize turning traveling corresponding to the driving state (steering angle θ), the total driving force of the left wheels 2FL and 2RL and the right wheels 2FR and 2RR are The target driving force of other normal motors is corrected so that the total driving force matches. Furthermore, in order to prevent deterioration in running stability, the driver is not recognized by adding vibration components. Instead, the target driving force is corrected using gain to be lower than the target driving force corresponding to the accelerator opening APO (normal target driving force before driving becomes impossible), and the motors 3FL, 3FR , 3RL, 3RR to make the driver aware that inability to drive, and to reduce the acceleration performance to ensure driving safety.

  In the driving force control in steps S4 to S6 and S8 to S10 described above, the maximum driving force of any of the motors 3FL, 3FR, 3RL, and 3RR is insufficient, and either the left or right motor (3FL, 3RL or 3FR, 3RR) If it is impossible to perform the above control due to the balance of the non-driveable motor position, such as when all the motors cannot be driven, use another normal motor (3FR, 3RR or 3FL, 3RL). The target driving force is corrected to be lower than the target driving force corresponding to the accelerator opening APO (the normal target driving force before driving becomes impossible), and the longitudinal acceleration with respect to the accelerator opening APO or steering Driving force control is performed so as to realize the traveling direction of the vehicle in the traveling state corresponding to the driving state, such as the turning traveling state with respect to the angle θ, and the traveling stability is ensured.

The driving force control according to the present invention has been described above for each vehicle speed and traveling direction.
Next, the driving force control and the effect on the failure (failure) of the drive motor will be described by classifying them according to the balance of the undriveable motor positions.
The portion described as the correction method 1 on the left side of the diagram of FIG. 5 is to maintain the target driving force by correcting the driving force of another normal driving motor when the driving motor becomes inoperable.
A state where one wheel cannot be driven will be described, for example, a state where the motor of the left rear wheel c cannot be driven as shown in the uppermost stage. In normal running, it is assumed that one driving force is applied to each of the four wheels a, b, c, and d. In this case, if the normal left front wheel a is corrected to give a driving force of 2, and if the normal right front wheel b and the right rear wheel d are each given one driving force, the maximum output of the motor of the left front wheel a will be exceeded. As long as there is no normal state, a traveling state corresponding to the driving state is realized and straight traveling and turning traveling are possible as in the normal state.
That is, the ratio of the total driving force of the left wheel and the total driving force of the right wheel is 1: 1 when normal and 1: 1 when unable to drive, and the left / right ratio does not change. Therefore, the running state can be maintained. And if the sum of the wheel driving force at the normal time and the sum of the wheel driving force at the time when the driving is impossible are made the same, the vehicle speed can be maintained.
Alternatively, when there is no margin in motor output, the vehicle driving speed and acceleration performance are reduced by reducing the total wheel driving force when driving is impossible compared to the total wheel driving force during normal operation. Secure. For example, in the upper stage of the correction method 1 shown in FIG. 5, if the maximum driving force of the driving motor for the left front wheel a is 1.5, a driving force of 2 is applied to the normal left front wheel a as shown in FIG. Cannot be corrected to give In this case, the maximum driving force of 1.5 is given to the left front wheel a, and the total driving force of the right wheels b and d is corrected by 0.75 each so as to match the left wheel a. As a result, although the vehicle speed and acceleration performance are lower than the driving state (accelerator input, accelerator opening APO), it becomes possible to realize the traveling direction of the vehicle corresponding to the driving state (steering input, steering angle θ). , Driving stability can be ensured.

  A state in which the two wheels cannot be driven, for example, as shown in the middle part of FIG. 5, will be described in which the left rear wheel c motor and the right rear wheel d motor cannot be driven. It is assumed that one driving force is applied to each of the four wheels a, b, c, d during normal operation. In this case, if correction is made so that two normal driving forces are applied to the left front wheel a and the right front wheel b, respectively, as long as the maximum output of the motor of the left front wheel a and the motor of the right front wheel b is not exceeded, A traveling state corresponding to the driving state is realized, and straight traveling and turning traveling are possible.

Further, as shown in the middle part of FIG. 5, the state in which the motor of the left front wheel a and the motor of the right rear wheel d cannot be driven will be described. Two normal driving forces are applied to the left rear wheel c and the right front wheel b, respectively. As long as the maximum output of the motor of the left rear wheel c and the motor of the right front wheel b is not exceeded, the traveling state corresponding to the driving state is realized and the vehicle can travel straight and turn as long as normal. become.
Or, when there is no margin in motor output or the driving state is a high speed vehicle speed range, reduce the total wheel driving force when driving is impossible compared to the total wheel driving force when normal As a result, the vehicle speed and acceleration performance are reduced to ensure running stability.

  However, in the case where it is impossible to appropriately correct the ratio of the left driving force and the right driving force due to the balance of the non-driveable motor position, for example, as shown in the lower part of FIG. The state in which the motor of the left and rear left wheels c cannot be driven will be described. Since the drive wheels are shifted to the right side, two normal driving forces are applied to the right front wheel b and the right rear wheel d, respectively. If the correction is made as described above, it becomes impossible to achieve straight traveling and right turn traveling. Therefore, if the driving state (steering angle θ) is left turning, the driving force of the right front wheel b is decreased to α, The driving force of the rear wheel d is decreased to β, and the vehicle continues to travel without impairing the traveling stability. Here, α <1 and β <1.

Next, another embodiment of the present invention will be described.
FIG. 4 is a system configuration diagram of a wheel independent drive type vehicle according to another embodiment. Components similar to those of the embodiment shown in FIG. 1 are denoted by common reference numerals, and different components are newly denoted by reference numerals. A detailed explanation will be given.
Individual inverters 13FL, 13FR, 13RL, 13RR and a drive current switching unit 15 are inserted as terminal boxes on the power line connecting the motors 3FL, 3FR, 3RL, 3RR and the battery 4 as a common power source. To do. Control unit 16 calculates the target driving force of wheel 2Fl and outputs a control command to inverter 13FL. The inverter 13FL performs inverter control so that the power supplied from the battery 4 is generated so as to generate the target driving force, and supplies it to the driving current switching unit 15. The drive current switching unit 15 normally connects the inverter 13FL and the motor 3FL, and supplies inverter-controlled power to the motor 3FL. The motor 3FL generates a target driving force, and the wheel 2Fl is driven to transmit the target driving force to the ground plane.

  The remaining wheels 2FR, 2RL, and 2RR are also driven to transmit the target driving force to the ground plane in the same manner as described above. Therefore, the drive current switching unit 15 normally connects the inverter 13FR and the motor 3FR, connects the inverter 13RL and the motor 3RL, and connects the inverter 13RR and the motor 3RR.

  The inverters 13FL, 13FR, 13RL, and 13RR are provided with failure detection sensors 14FL, 14FR, 14RL, and 14RR. The failure detection sensors 14FL, 14FR, 14RL, and 14RR individually monitor the failure of the inverters 13FL, 13FR, 13RL, and 13RR by monitoring the current supplied from the inverters 13FL, 13FR, 13RL, and 13RR to the drive current switching unit 15. Can be detected. When detecting a failure, the failure detection sensors 14FL, 14FR, 14RL, and 14RR output signals to the control unit 16.

  While the failure detection signal is input, the control unit 16 performs inverter switching control. That is, the control unit 16 outputs a switching command to the driving current switching unit 15 and assigns a normal inverter with priority over the driving motors 3FL and 3FR of the front wheels 2FL and 2FR as will be described later. Thereby, the vehicle can ensure the stable running equivalent to the front wheel (two-wheel) drive vehicle.

The part described as the correction method 2 on the right side of the chart of FIG. 5 is a chart showing the inverter switching control for the failure (failure) of the inverter classified by the balance of the failed inverter position. Based on this chart, the inverter switching method will be described in detail below.
In a state where one wheel cannot be driven, that is, any one of the inverters 13FL, 13FR, 13RL, and 13RR has failed (failed), for example, as shown in the upper part of FIG. A state in which the inverter 13RL of the drive motor of the wheel 2RL) has failed will be described. In normal running, it is assumed that one driving force is applied to each of the four wheels a, b, c, and d. In this case, the inverter switching control is not executed, and the normal left front wheel b is corrected by applying a driving force of 2 to the normal left front wheel a as in the case of the drive motor failure described above and in the correction method 1 in FIG. , One driving force is applied to each of the right rear wheels d.
Alternatively, the normal left front wheel a may be corrected so that a driving force of 2 is applied, a driving force of 2 is applied to the normal right front wheel b, and a driving force of 0 is applied to the right rear wheel d. ) Ensures stable running equivalent to the driving vehicle.

In a state in which the two wheels cannot be driven, that is, any two inverters among the inverters 13FL, 13FR, 13RL, and 13RR fail (fail) and, for example, as shown in the middle part of FIG. A state in which the inverter 13RL of the drive motor of the drive motor corresponding to the wheel 2RL and the inverter 13RR of the drive motor of the right rear wheel d (corresponding to the wheel 2RR in FIG. 4) have been lost will be described. It is assumed that one driving force is applied to each of the four wheels a, b, c, d during normal operation. In this case, the inverter switching control is not executed, and correction is performed so that two normal driving forces are applied to the left front wheel a and the right front wheel b, respectively, in the same manner as the driving motor failure described above and in the correction method 1 in FIG. .
In the above-mentioned inverter failures shown in the upper and middle stages of FIG. 5, in any case, since the inverters related to the pair of left and right wheels a and b operate normally, there is no need to execute inverter switching control. This can be dealt with by the aforementioned driving force control shown on the left side of FIG.

  On the other hand, as shown in the middle of FIG. 5, the inverter 13FL of the drive motor for the left front wheel a (corresponding to the wheel 2FL in FIG. 4) and the inverter 13RR of the drive motor for the right rear wheel d (corresponding to the wheel 2RR in FIG. 4). In the case of failure, the inverter switching control is not executed, and if only the driving force distribution is corrected so that two normal driving forces are applied to the left rear wheel c and the right front wheel b, respectively, Similarly, although the traveling state corresponding to the driving state is realized and theoretically straight traveling and turning traveling are possible, the driving wheels c and b are not arranged symmetrically but are arranged obliquely, so that the driving force Control is not easy, and there is a concern that a horizontal plane behavior (yaw angle) may occur in the vehicle.

  Therefore, as shown on the right side of the middle stage in FIG. 5, the inverter 13FL of the drive motor for the left front wheel a (corresponding to the wheel 2FL in FIG. 4) and the inverter 13RR of the drive motor for the right rear wheel d (corresponding to the wheel 2RR in FIG. 4) In the case of failure, a normal inverter is assigned with priority over the drive motor 3FL of the front wheels 2FL. That is, the drive current switching unit 15 disconnects the drive motor 3FL and the failed inverter 13FL, disconnects the other drive motor 3RL and the normal inverter 13RL, and connects the drive motor 3FL and the other normal inverter 13RL to each other. Inverter switching control for connecting is executed. In this way, the drive current switching unit 15 disconnects the connection between the motor 3FL and the inverter 13FL that is in failure, and the control unit 16 connects the normal inverter 13RL of the other motor 3RL to the motor 3FL. By controlling the driving force of the driving motor 3FL of the left front wheel a using the inverter 13RL and applying two driving forces to each of the left front wheel a and the right front wheel b arranged symmetrically, the driving characteristics are controlled by the driver. It is possible to follow the driving state to be performed, and the vehicle can ensure a stable traveling equivalent to that of a front wheel (two-wheel) drive vehicle.

  Alternatively, as shown in the lower part of FIG. 5, when the inverter 13FL of the drive motor for the left front wheel a and the inverter 13RL of the drive motor for the left rear wheel c have failed, the drive current switching unit 15 has failed with the drive motor 3FL. The inverter 13FL is disconnected, and inverter switching control for connecting the drive motor 3FL and the remaining normal inverter 13RR is executed. Thus, the control unit 16 controls the driving force of the driving motor 3FL for the left front wheel a using the inverter 13RR, and applies two driving forces to each of the left front wheel a and the right front wheel b. ) It is possible to ensure stable running equivalent to the driving vehicle. Therefore, according to the inverter switching control in this case (correction method 2 in FIG. 5), it is possible to realize straight traveling and right turn traveling, which is preferable compared to the correction method 1 shown on the left side in the lower part of FIG. It is possible to achieve stable running.

Note that the above inverter switching control (correction method 2 in FIG. 5) obtains traveling stability equivalent to that of a front-wheel (two-wheel) drive vehicle by controlling the driving force of the wheels a and b arranged symmetrically. In addition, the driving stability of the rear wheels c and d may be controlled to ensure traveling stability equivalent to that of a rear wheel (two-wheel) drive vehicle. Alternatively, although not shown in the figure, in a vehicle having a plurality of pairs of three or more pairs of wheels arranged symmetrically in the left-right direction, any one set of wheels arranged symmetrically by the inverter switching control Driving stability can be obtained by controlling the driving force.
Although not shown in the figure, in addition to inverters 13FL, 13FR, 13RL, and 13RR, a spare inverter is provided, and a spare inverter is connected to the motor that is the target of driving force control instead of the failed inverter. May be.
In addition, in the above inverter switching control (correction method 2 in FIG. 5), when the target driving force of the drive motor exceeds the maximum power capacity (maximum output) of the normal inverter and the driving force is insufficient. In the state in which the maximum power capacity that can be generated by a normal inverter is output to the drive motor, the driving force of the other normal drive source controls the driving state of the vehicle corresponding to the driving state. Driving force correction control is performed to realize the direction.

  By the way, according to the above-described embodiment, the control unit 6 travels in the traveling direction from the steering angle θ from the steering angle sensor 9 and the accelerator opening AP0 from the accelerator opening sensor 11 during low-speed straight travel and slow turn. When the driving state of the motor 3FL, 3FR, 3RL, 3RR is detected by the signal from the motor driving failure detection sensor 7FL, 7FR, 7RL, 7RR, Since the control unit 6 corrects the target driving force of the remaining normal motors (any of 3FL, 3FR, 3RL, and 3RR) and executes the target driving force corresponding to the accelerator opening APO, FIG. As shown in the figure, it is possible to output the same driving force as in the normal state even when the vehicle cannot be driven, and the vehicle speed can be changed even after the driving failure occurs without stopping the wheel driving force as in the conventional case. Prevent You can continue to travel in normal operation the same accelerator operation.

  Then, since the driving force of the remaining normal wheels 2 is corrected so that the sum of the driving forces of the left wheel 2 and the driving force of the right wheel 2 match even in a non-driveable state, the drive is impossible. Even after it occurs, the turning direction can be prevented from becoming unstable, and straight running or turning can be continued by the same steering operation as in normal times.

  Also, according to the present embodiment, the target driving force F1, F2, F3, F4 corresponding to the accelerator opening APO using the gain by the driving force correction unit 25 during high-speed straight traveling, low-speed turning, and high-speed turning. Therefore, the acceleration performance can be reduced, and the vehicle can continue to travel without impairing the traveling stability even after the inability to drive. Therefore, it is possible to improve the safety of the drive impossible state. In addition, the driver knows that the motor 3FL, 3FR, 3RL, 3RR has failed without impairing the running stability by recognizing that the vehicle acceleration has slowed with respect to the accelerator pedal depression amount (accelerator opening APO). Can do.

  The driving force control described above and described in the correction method 1 in FIG. 5 is based on the premise that there is a margin in the output of other normal drive motors, but other normal drive motors (3FL, 3FR , 3RL, 3RR) If the target drive force after correction cannot be realized due to insufficient maximum output (any of 3FL, 3FR, 3RL, 3RR) Outputs the maximum driving force and corrects the driving force commands F1, F2, F3, and F4 to the decreasing side so that the total target driving force of the motor on the opposite side in the left-right direction matches the maximum driving force. You can continue running without compromising your performance.

  When the motors 3FL, 3FR, 3RL, and 3RR cannot be driven, a vibration component in the vehicle front-rear direction is added to the driving force in a vehicle speed range that does not impair warning running stability by the indicator 12. , 3FR, 3RL, 3RR can not be driven sensibly, only the warning by the indicator 12, the driver does not notice the driving impossible state, or continue to drive forcibly while noticing the driving impossible state The problem can be solved and both convenience and safety can be achieved.

  Alternatively, when the motors 3FL, 3FR, 3RL, and 3RR cannot be driven, the driver does not feel a change in the running state. By not doing so, the driver can be alerted at the time of starting / stopping or slowing down.

  Further, according to the above-described embodiment shown on the right side of FIGS. 4 and 5, while the failure of any one of the inverters 13FL, 13FR, 13RL, and 13RR is detected, the motor and the failed inverter are By disconnecting the connection between the motor and a normal inverter included in the other motor, so that the motor is brought into a running state corresponding to the driving state detected by the sensors 9, 10, and 11. By controlling the driving force, it is possible to output the same driving force as normal using the remaining normal inverters even when the inverter has failed, and stop the wheel driving force as before. In addition, the vehicle speed can be prevented from changing even after driving failure occurs, and the vehicle can continue to travel with the same accelerator operation as during normal operation.

  In particular, in this embodiment, inverter switching control is executed as shown in the middle of FIG. 5 (correction method 2) to control the driving force of the driving motors 3FL and 3FR of the pair of wheels a and b arranged symmetrically. Therefore, it is possible to avoid the oblique arrangement of the drive wheels, to eliminate the concern that the horizontal plane behavior (yaw angle) occurs in the vehicle, and to ensure the stable running equivalent to the front wheel (two-wheel) drive vehicle. it can.

Further, as shown in the lower part of the right side of FIG. 5 (correction method 2), the failure of the inverter 13FL of the wheel a out of the inverters 13FL and 13FR related to the drive motors of the pair of wheels a and b arranged symmetrically. If detected, a normal inverter 13RR related to the drive motor for the right wheel d is connected to the drive motor 3FL for the left front wheel a so that the drive force control of both the left and right motors 3FL, 3FR can be achieved. Therefore, it is possible to perform straight running and turning while avoiding the displacement of the drive wheels to the left or right, and compared with the correction method 1 shown on the left side of FIG. Thus, stable running can be suitably realized.
In addition to the above-described embodiment that preferentially controls the driving force of the front wheels a and b, the driving force of the rear wheels c and d may be controlled preferentially.

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 block diagram according to function which shows the control unit which comprises the driving force control apparatus. It is a flowchart which shows the control program which the same driving force control apparatus performs. FIG. 6 is a power distribution diagram of a four-wheel independent drive type electric vehicle including a drive force control device for a wheel independent drive type vehicle according to another embodiment of the present invention. It is a graph which classifies and shows the driving force control which the same driving force control apparatus performs according to a non-driveable motor position.

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 4 Drive Motor battery 5FL Motor controller for left front wheel drive motor 5FR Motor controller for right front wheel drive motor 5RL Motor controller for left rear wheel drive motor 5RR Motor controller for right rear wheel drive motor 6 Control unit
7FL Motor drive inability detection sensor for left front wheel
7FR Motor drive inability detection sensor for right front wheel
7RL Motor drive inability detection sensor for left rear wheel
7RR Motor drive inability detection sensor for right rear wheel 8 Steering wheel 9 Steering angle sensor 10 Vehicle speed sensor 11 Accelerator opening sensor 12 Indicator
13FL Left front wheel drive motor inverter
13FR Inverter for right front wheel drive motor
13RL Inverter for drive motor for left rear wheel
13RR Inverter for right rear wheel drive motor 15 Drive current switching unit 21 Each wheel drive source monitoring unit 22 Turning / straight running determination unit 23 Vehicle speed region determination unit 24 Abnormal drive source determination unit 25 Drive force correction unit

Claims (10)

In a driving force control device that is used in a wheel independent driving type vehicle that independently drives a wheel with an individual driving source, and individually controls the driving force of the wheel,
Driving state detecting means for detecting the driving state of the wheel independent drive vehicle;
Drive source failure detection means for detecting the failure of each drive source,
While the failure of one of the drive sources is detected by the means, the running state of the vehicle using another normal drive source is changed to a running state corresponding to the driving state detected by the driving state detecting means. A driving force control device for a wheel independent drive type vehicle, wherein the driving force control is performed for a normal driving source so as to achieve the above.   2. The driving force control apparatus according to claim 1, wherein the traveling state includes a traveling direction of the vehicle and a total driving force of the vehicle.   3. The driving force control device according to claim 1 or 2, wherein a driving state corresponding to a driving state can be realized by controlling the driving force of the normal driving source, the driving force output of the normal driving source with respect to the depression amount of the accelerator pedal. A driving force control device, characterized in that a driving force gain, which is a characteristic, is lowered so that vehicle behavior is less likely to be unstable.   In the driving force control device according to any one of claims 1 to 3, when a running state corresponding to the driving state cannot be realized due to a shortage of the maximum driving force of the normal driving source, The vehicle in the driving state corresponding to the driving state is controlled by the driving force control of another normal driving source under the state that the driving source which has generated the shortage of the maximum driving force outputs the maximum driving force. A driving force control device for a wheel independent drive type vehicle, characterized in that it is configured to realize the traveling direction of the vehicle.   5. The driving force control apparatus according to claim 1, wherein during the detection of the failure by the driving source failure detecting means, a vibrational driving force is generated in another normal driving source. A driving force control apparatus configured to make a driver recognize a failure.   The driving force control apparatus according to any one of claims 1 to 5, wherein when the drive source fails during a slow speed straight line that does not cause the driver to feel a change in traveling state due to a failure of the drive source, A driving force control apparatus configured to prohibit driving force control of a normal driving source.   7. The driving force control device according to claim 6, further comprising an alarm device for warning and recognizing a driver of a failure of the driving source that is traveling at a slow speed. In the driving force control device according to any one of claims 1 to 7,
The drive source is a motor having individual inverters,
While the failure of one of the inverters is detected by the drive source failure detection means, the operation detected by the operation state detection means is performed by connecting a normal inverter to the motor instead of the inverter that has failed. A drive force control device for a wheel independent drive type vehicle, wherein the drive force of the motor is controlled so as to achieve a running state corresponding to the state. The driving force control apparatus according to claim 8,
While the failure of any inverter is detected by the drive source failure detection means, the connection between the motor and the failed inverter is disconnected,
A driving force control device for a wheel independent drive type vehicle characterized in that a normal inverter connected to another motor is connected to the motor so that a normal inverter is connected to the motor instead of the failed inverter. . The driving force control apparatus according to claim 9,
The wheel comprises at least one pair of wheels arranged symmetrically,
While the drive source failure detecting means detects the failure of the inverter included in the motor driving the set of wheels, the normal inverter included in the motor driving the other wheel and the set of wheels. A drive force control device for a wheel independent drive type vehicle, wherein the drive force control of a motor for driving a pair of wheels arranged symmetrically is connected to a motor for driving the vehicle.

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