JPH10295004A - Drive control device for electric vehicles - Google Patents

Abstract

(57) [Problem] To realize a wheel-in motor type four-wheel drive electric vehicle capable of executing 4WD control and TRC / ABS equivalent control. SOLUTION: When only one of four drive wheels is slipping (a), non-slip wheels on the same side of the left and right sides as the slip wheel are slipped if no slip occurs. Distribute the output torque that should have been distributed to the wheels. When there are two slip wheels and one each on the left and right sides (b-1, b-2), the torque output that would have been allocated to the slip wheel if it was not slipping is transferred to the same side. Allocate to certain non-slip wheels. When there are three slip wheels (c), when there are four slip wheels (d), and when there are two slip wheels and both the slip wheels are on the left or right side (b-3), TR
The C / ABS equivalent control is executed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applied to an electric vehicle having m or more (m is a natural number of 3 or more) driving wheels and having a motor provided for each driving wheel, and the running stability during a slip. To a drive control device that controls each motor so that the motor speed increases.

[0002]

2. Description of the Related Art For a conventional engine vehicle, the output of the engine is distributed to a total of four wheels in front, rear, left and right, so that even if one or two of the wheels slip, the vehicle is driven while maintaining running stability. A technology called four-wheel drive (4WD) has been developed which enables the driving. The 4WD technology is also applicable to an electric vehicle that is a vehicle propelled by a vehicle-mounted motor. For example, 1
An electric vehicle of the type that mechanically distributes the output of four motors to four wheels is essentially the same as a conventional engine vehicle that mechanically distributes the output of the engine to four wheels in terms of a method of supplying torque to each drive wheel. There is no difference. Thus, 4WD in conventional engine vehicles can be applied relatively simply to this type of electric vehicle.

There is an electric vehicle of a drive wheel independent drive type in which a motor is provided for each drive wheel so that each drive wheel can be driven to rotate independently. In this type of electric vehicle, a motor is provided for each driving wheel, so a distribution mechanism such as a differential gear is not required, and therefore, low transmission loss and low energy consumption can be used, so that the on-board battery can be downsized. It has the advantage that the size of the motor can be made smaller than that of a normal so-called one-motor type electric vehicle because it can be made as much as possible. For example, Japanese Unexamined Patent Application Publication No. 2-262806 discloses an electric vehicle with independent driving wheels, in which motors are provided on a total of four wheels, front, rear, left and right, so that each driving wheel can be rotated independently. As a typical example of each drive wheel independent drive type electric vehicle, an electric vehicle in which a motor is embedded in or integrated with each drive wheel, that is, a wheel-in motor type electric vehicle is listed. The wheel-in motor type electric vehicle has advantages such that the motor is built in the drive wheel, so that the integration is high and the cabin space is widened.

[0004] Each drive wheel independent drive type electric vehicle is different from a conventional engine vehicle or a one-motor type electric vehicle in which mechanical power is distributed to each drive wheel using a distribution mechanism such as a differential gear, in that torque is supplied to each drive wheel. In terms of approach, they are essentially different. Therefore, 4WD in a conventional engine vehicle or a one-motor type electric vehicle cannot be simply applied to each driving wheel independent driving type electric vehicle. Therefore, for example, in the vehicle described in Japanese Patent Application Laid-Open No. 2-262806, the value of the rotation speed command for each motor is determined according to the road surface condition, and the motor speed control is executed based on the determined rotation speed command value. 4WD is running. That is, 4WD is realized by utilizing the characteristic of each drive wheel independent drive type electric vehicle that "each drive wheel can be driven to rotate independently".

[0005]

As a method of controlling the output of the motor, there is a torque control in addition to the speed control (rotation speed control). The torque control has an advantage that it is easy to faithfully fulfill acceleration / deceleration requests from a vehicle operator. Therefore, it is desirable to control the torque of the motor even in each drive wheel independent drive type electric vehicle. However, in the electric vehicle of each drive wheel independent drive type that controls the torque of the motor output, a new problem arises when trying to realize 4WD by paying attention to the characteristic that each drive wheel can be driven to rotate independently. In other words, the fact that "each drive wheel can be independently driven to rotate" means, in other words, that "commands relating to the output values must be constantly given to all the provided motors". What value of the output torque should be instructed to the motor corresponding to the driving wheel exhibiting the slip or its tendency, and what value of the output torque should be instructed to the motor corresponding to the other driving wheels. Issues such as what to do are new issues.

One object of the present invention is to determine the occurrence of slip or its tendency in each drive wheel, particularly the slip or its tendency, in each drive wheel independent drive type electric vehicle represented by a wheel-in motor type electric vehicle. By determining the command value of the output torque according to the position and the number of the driving wheels (slip wheels) and the other driving wheels (non-slip wheels) present, 4WD (more generally, m-wheel drive: mWD, where m is a natural number of 3 or more). One of the objects of the present invention is to appropriately control the TRC (Truction Control) or ABS (Anti
By starting the control corresponding to the lock break system, it is possible to maintain and achieve the running stability of the vehicle, and this control, that is, the TRC / ABS equivalent control is realized by the motor torque control and the pressure of the braking fluid, for example, Another object of the present invention is to eliminate the need for hydraulic operation.

[0007]

According to a first aspect of the present invention, there is provided:
A drive control device that is mounted on an electric vehicle having m or more drive wheels that are each driven to rotate by the output torque of the corresponding motor, and that commands the output torque value to each motor. A slip wheel detecting means for discriminating between a slip wheel and a non-slip wheel according to whether or not the vehicle is running, and a new yaw direction moment acts on the vehicle body when at least one non-slip wheel is on the left and right sides of the vehicle body. And m-wheel drive control means for instructing each motor to output a torque value after adjustment. In this configuration, if at least one non-slip wheel is provided on each of the left and right sides of the vehicle body, the output torque of each motor is controlled (for example, the output torque of the motor corresponding to the slip wheel is cut, and the required addition is performed only by the non-slip wheel. By controlling the output torque of each motor so that deceleration can be realized, mWD is realized while preventing generation of a yaw direction moment. This allows
The highly reliable running stability control that can quickly recover the running stability at the time of a slip is realized.

A second configuration of the present invention is mounted on an electric vehicle having m or more (m is a natural number of 3 or more) drive wheels, each of which is rotationally driven by an output torque of a corresponding motor. In a drive control device for instructing an output torque value, a slip wheel detecting means for discriminating each drive wheel into a slip wheel and a non-slip wheel depending on whether or not the current slip is occurring, and the non-slip wheel is located on the left side of the vehicle body. And TRC / ABS equivalent control means for instructing an output torque value to each motor after performing an adjustment according to the slip state of the slip wheel when there is no one and there is no one on the right side. It is characterized by the following. In this configuration, the TRC / A
Since the BS-equivalent control is realized, the running stability can be quickly restored in the event of a slip without operating the pressure of the braking fluid, for example, the hydraulic pressure, and thus without providing a valve, a pump or the like. Further, since the TRC / ABS equivalent control is activated in accordance with the position and the number of the slip wheels and the non-slip wheels, the TRC / ABS equivalent control operates under appropriate conditions, and therefore, highly reliable running stability control is performed. Is achieved.

The above configuration will be described in more detail with reference to embodiments. In the description of the present application, the present invention is described as an invention of a "drive control device", but the present invention can also be expressed as a "drive control method", an "electric vehicle" or the like. Changes to such representations will be readily apparent to those of skill in the art in light of the present disclosure. In the following description, a wheel-in type three-phase AC motor is exemplified, but the present invention can be applied to other types of motors. The present invention is applicable to mWD as well as 4WD. The method of TRC / ABS control is disclosed in Japanese Patent Application Laid-Open No. 8-182119 and Japanese Patent Application No. 9-8693.
Is not limited to those disclosed in the item.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION

(1) System Configuration FIG. 1 shows a system configuration of an electric vehicle suitable for carrying out the present invention. The electric vehicle shown in this figure is a wheel-in motor type four-wheel drive electric vehicle. That is, the right front wheel 10FR, the left front wheel 10FL, the right rear wheel 10RR, and the left rear wheel 10RL are connected to the motors 12FR, 12FL, 1FL, respectively.
2RR and 12RL are incorporated. FIG. 2 shows an example of how to incorporate the right rear wheel 10RR as an example. In this figure, while the rotor is fixed inside the wheel 16 so as to be able to rotate integrally with the tire 14, the stator 24 is fixed to the rear axle 22 via the motor shaft 20, and the stator 24 is connected to the rotor 18 via bearings and the like. Has been joined. Further, a rotor magnet (permanent magnet) 26 is arranged so as to face the outer wall surface of the rotor 18 with a minute gap from the stator 24.
While the stator 24 has a stator winding 28
And a cable 30 for passing a current through the stator winding 28 is connected to the stator winding 2 via the motor shaft 20.
8 is connected. In such a structure, by supplying an alternating current to the stator winding 28 via the cable 30, the rotor 18 rotates and generates propulsion of the vehicle. In practicing the present invention, other types of wheel-in motor structures may be used. In addition, the present invention can be applied to an electric vehicle that is not a wheel-in motor type as long as a motor is provided for each driving wheel.

The battery 32 shown in FIG.
2FR, 12FL, 12RR, and 12RL. The discharge output of the motor 12RR is supplied to the motor 12FR via the inverter 34FR, to the motor 12FL via the inverter 34FL, and to the motor 12RR via the inverter 34RR.
And the motor 12RL via the inverter 34RL
, Respectively. Inverter 34FR, 3
4FL, 34RR, and 34RL are a type of power converter. That is, under the control of the motor control unit 36FR, the inverter 34FR converts the discharge output (DC) of the battery 32 into a power format (three-phase AC in this figure) suitable for the motor 12FR. Similarly, the inverter 34FL controls the inverter 34R under the control of the motor control unit 36FL.
R converts the discharge output of the battery 32 into a power format suitable for the corresponding motor under the control of the motor control unit 36RR and the inverter 34RL under the control of the motor control unit 36RL. Further, the motor controller 36FR responds to the torque command TFR, the motor controller 36FL responds to the torque command TFL, the motor controller 36RR responds to the torque command TRR, and the motor controller 36RL responds to the torque command TRL. By controlling the corresponding inverter, a torque corresponding to the corresponding torque command is output from the corresponding motor. Motor control unit 36F
The torque commands TFR, TFL, TRR, and TRL given to R, 36FL, 36RR, and 36RL are all generated by the vehicle control unit 38. The motor control units 36FR, 36FL, 36RR, and 36RL have a function of insulating and separating the corresponding inverter and the vehicle control unit 38 in addition to the power conversion control described above. Further, the motors 36FR, 36FL, 36RR and 36RL
The control of the corresponding inverter is performed based on the detected current value of each phase of the corresponding motor obtained from a current sensor (not shown) or the estimated current value of each phase of the corresponding motor obtained from the rotor angle position or the like.

The vehicle control unit 38 controls the motors 12FR and 12FR.
A control member for controlling the output torque of the FL, 12RR, and 12RL, monitoring and controlling the state of each component mounted on the vehicle, notifying the vehicle occupant of the vehicle state, and other functions, and a conventionally used electronic control unit (ECU) ) Can be realized mainly by software modification. Vehicle control unit 38
The outputs of the sensors provided in each part of the vehicle are input to the, and the vehicle control unit 38 uses the outputs of the sensors for motor output control and vehicle state monitoring.

For example, a wheel speed sensor 40FR (for example, a resolver) provided on a wheel of the right front wheel 10FR includes:
A signal indicating the wheel speed VFR of the right front wheel 10FR (for example, a pulse signal for each minute angular position displacement) is generated, and the vehicle control unit 3
8 Similarly, the wheel speed sensor 40FL provided on the wheel of the left front wheel 10FL outputs a signal indicating the wheel speed VFL of the left front wheel 10FL, and the wheel speed sensor 40RR provided on the wheel of the right rear wheel 10RR outputs a signal indicating the right rear wheel 10RR. The wheel speed sensor 40RL provided on the wheel of the left rear wheel 10RL outputs a signal indicating the wheel speed VRR of the left rear wheel 1
A signal indicating a wheel speed VRL of 0RL is generated, respectively.
It is supplied to the vehicle control unit 38. Also, the accelerator sensor 42
Transmits a signal indicating the amount of depression of an accelerator pedal (not shown), that is, the accelerator opening VA, to the brake sensor 44.
Transmits a signal indicating the amount of depression of the brake pedal 56, that is, the braking force FB, to the shift position switch 46.
Generates a signal indicative of a shift range of a shift lever (not shown) (and a shift lever position within the range in an engine brake range or the like), that is, a shift position. Further, the sensor 48 is a sensor for detecting a steering state, a motion state of the vehicle, and the like, for example, a steering angle sensor, and generates a signal indicating a result of the detection, for example, a signal indicating a steering angle δt. When the outputs of these sensors are input to the vehicle control unit 38, they are converted into data in a format that can be processed by the vehicle control unit 38. The vehicle control unit 38 uses the converted data to generate the torque command T
Determination of FR, TFL, TRR, and TRL, switching of the control method, and the like are executed.

In FIG. 1, a braking system is used in which the front, rear, left and right wheels are braked by both hydraulic pressure and regeneration.
That is, when the brake pedal 56 is depressed, the hydraulic pressure generated in the master cylinder 58 in response to the depression is applied to the wheels 10.
Wheel cylinders 60FR, 60F provided corresponding to FR, 10FL, 10RR, and 10RL, respectively.
L, 60RR, and 60RL, and acts on the corresponding brake wheels 62FR, 62FL, 62RR, and 62RL, and the wheels 10FR, 10FL, 10RR, and 10R.
L is given a braking torque. On the other hand, the braking force (master cylinder 5
The vehicle controller 38 generates torque commands TFR, TFL, TRR, and TRL for regeneration in accordance with the (FB8) oil pressure FB. Therefore, as shown in FIG. 3, the distribution of the braking force in the vehicle of FIG. 1 is a distribution in which both the hydraulic regeneration increases as the braking force FB (“pedal input” on the horizontal axis) increases. In this way, the hydraulic system and the regenerative system
4 and thereafter, the vehicle can be evacuated on the other side even if one of the hydraulic pressure and the regeneration fails. Further, the hydraulic system is not provided with a pump, and the valve is merely provided with a proportioning valve 59 for distributing the hydraulic braking force back and forth. The system configuration is simplified as compared with a system that shuts off the hydraulic pressure. One of the reasons why there is no need to provide a pump in the hydraulic system and the number of valves on the hydraulic system can be minimized is that the motors 12FR, 12F
This is a characteristic configuration of the present embodiment in which running stability control is performed using control of output torques of L, 12RR, and 12RL.

(2) Function of Vehicle Control Unit FIG. 4 is a flowchart showing functions of the vehicle control unit 38 in the present embodiment. Although the present invention can be implemented by hardware logic or software, the following description uses a flowchart for clarifying the procedure. The vehicle control unit 38 first detects the vehicle body speed VS as shown in FIG.
0). Various procedures can be adopted as the procedure for detecting the vehicle body speed VS. For example, it is preferable to employ the procedure shown in FIG. In FIG. 5, the vehicle control unit 3
8 first resets working variables such as Nslip, VS, etc. (200), and then resets wheels 10FR, 10FL, 10FL
With respect to either RR or 10RL, the wheel angular acceleration dω / dt is calculated (202). The following equation is used to calculate the wheel angular acceleration.

## EQU1 ## dω / dt ← (1 / R) · dV / dt can be used. In the above formula, R is a wheel radius,
V and ω are the wheel speed and the wheel angular speed of the wheel for which the wheel angular acceleration is to be obtained at present. Vehicle control unit 3
8 indicates that the absolute value of the wheel angular acceleration dω / dt thus determined does not exceed a predetermined threshold (20
4) It is determined that no slip or tendency has occurred for the wheel, and the wheel speed V of the wheel is added to the variable VS (206). Conversely, if the absolute value of the angular acceleration dω / dt exceeds a predetermined threshold value, it can be considered that the wheel is slipping or the tendency is generated. Nslip, which is a variable for counting the number of wheels (slip wheels) that can be regarded as occurring, is incremented by 1 (208). The vehicle control unit 38 determines in step 206 or 2
After executing step 08, the wheel position and wheel speed V are stored in a built-in memory or the like (210). Vehicle control unit 38
Executes the procedure according to steps 202 to 210 for all drive wheels (212).

After determining whether all the drive wheels are slip wheels or non-slip wheels, the vehicle control unit 38 determines whether the number Nslip of the slip wheels is equal to four, that is, whether all the drive wheels are slip wheels. Is determined to indicate whether or not the vehicle is slipping or that tendency (21).
4). Normally, all the drive wheels do not slip or show the tendency at the same time.
The vehicle speed VS is calculated by dividing by Nslip, that is, the number of non-slip wheels (216). Conversely, Nsl
If ip = 4 holds, a search is made to find out which of the drive wheels last started to slip using information stored in the past when step 210 was executed (218). The vehicle control unit 38 uses, as the vehicle body speed VS, the value of the wheel speed V that the drive wheel found as a result of this search, that is, the last wheel that started slipping, had immediately before it started slipping ( 220).

As described above, in the present embodiment, the vehicle body speed VS can be determined relatively accurately by calculating the vehicle body speed VS only from the wheel speeds of the non-slip wheels in principle. The torque command value provisionally determined in the procedure described above is made appropriate. Also, even when all four wheels are slipping or exhibiting the tendency, the wheel speed that had just before the wheel that started to slip last started to be slipped is used as the vehicle speed VS. The vehicle speed information having the characteristic can be used for provisionally determining the torque command value. Step 216 or 2
After the execution of 20, the operation of the vehicle control unit 38 returns to FIG.

In FIG. 4, after detecting the vehicle speed VS, first, a determination regarding a steering state or a vehicle motion state is executed (102). When it is deemed necessary in view of the steering state or the vehicle motion state, the vehicle control unit 38
Executes the target yaw rate adaptation control and the target slip angle adaptation control (for example, the slip angle 0 control) (104). For example, when the sensor 48 is a steering angle sensor, when the absolute value of the detected steering angle δt is equal to or larger than a predetermined threshold, that is, when it is recognized that the vehicle operator is performing steering. The target yaw rate adaptation control or the target slip angle adaptation control is executed in order to prevent or suppress the occurrence of vehicle body running instability due to steering.

FIG. 6 shows an example of the procedure of the target yaw rate adaptation control or the target slip angle adaptation control. In the procedure shown in FIG. 6, the vehicle control unit 38 first determines the accelerator on / off state that can be determined based on the output of the accelerator sensor 42, the shift position given by the shift position switch 46, the steering angle δt given from the sensor 48, A coupling coefficient group is selected based on dδt / dt or the like that can be calculated based on the result (300). The vehicle control unit 38
Further, a wheel acceleration dV / dt is obtained for each wheel, and a road surface friction coefficient μ is calculated based on the wheel acceleration dV / dt (302). The vehicle control unit 38 determines a correction coefficient k for each wheel based on the road surface friction coefficient μ and the steering angle δt and using the coupling coefficient group selected in step 300 (304). The vehicle control unit 38
When the accelerator is on (306), the wheel speed V
From the powering torque map based on the accelerator opening VA and the shift position (308), and when the accelerator is off (306), the wheel speed V, the braking force FB and the regenerative torque map based on the shift position (31).
0), a torque command is provisionally determined for each wheel. The powering torque map is, for example, a map showing the rotation speed torque characteristic of the motor in a region where the rotation speed and the torque are both positive as shown in FIG. 7, and the regenerative torque map is such that the rotation speed is positive as shown in FIG. 4 is a map showing a rotation speed torque characteristic of a motor in a negative torque region.

The vehicle control unit 38 determines in step 308 or 3
A torque command is determined by multiplying the torque command provisionally determined at 10 by the correction coefficient determined at step 304 (312), and the determined torque command is output to the corresponding motor control unit (314). Therefore, depending on the value of the coupling coefficient group to be selected in step 300 and the setting method of the correction coefficient k in step 304, a torque command during execution of the target yaw rate adaptation control or the target slip angle adaptation control is taken. The possible range may be a value belonging to the regeneration region even when the accelerator is on, as shown in FIG. 9, and may be a value belonging to the powering region even when the accelerator is off. By performing such control, in the present embodiment,
The running stability of the vehicle body during steering is improved.

For the target yaw rate adaptation control and the target slip angle adaptation control, refer to the disclosure of Japanese Patent Application No. 9-8693 proposed by the present applicant. Also, in place of the target yaw rate adaptation control and the target slip angle adaptation control, a method of performing traveling stability control using a plurality of state quantities indicating the motion state of the vehicle including the yaw rate acting on the vehicle body may be adopted. Good. Regarding this method, refer to Japanese Patent Application No. 9-68571 previously proposed by the present applicant. After ending the procedure shown in FIG. 6, the operation of the vehicle control unit 38 returns to FIG. The vehicle control unit 38 determines whether an end request has been given at this time (106).
That is, unless an operation such as turning off an ignition switch (not shown) is performed by the vehicle operator,
Returning to step 100, the operation is repeated. If an end request has been given, a predetermined end process is executed and the procedure of FIG. 4 ends (108).

In step 102 executed after detecting the vehicle speed VS, if it is recognized that it is not necessary to execute the target yaw rate adaptation control or the target slip angle adaptation control in view of the steering state and the vehicle body temperature state, The vehicle control unit 38 executes a procedure related to 4WD control in principle (110). The vehicle control unit 38 controls the 4WD control 11
When starting 0, first, a determination / classification process relating to the number of slip wheels Nslip detected in the procedure for detecting the vehicle speed VS is executed. That is, when the detected number of slip wheels Nslip is equal to 4, that is, when all the drive wheels show slip or a tendency thereof,
12), when the number of slip wheels Nslip is equal to 3, that is, when there is only one drive wheel that does not show slip or its tendency (114), the operation of the vehicle control unit 38 is equivalent to TRC / ABS instead of 4WD control 110 Control is transferred to (116). Also, the number of slip wheels Nsl
Even when ip is equal to 2, that is, when there are two driving wheels that do not show a slip or the tendency (118), the detected slip wheels are both left wheels or both right wheels. If it is a wheel (120),
The control shifts to TRC / ABS equivalent control (116). Further, even when it is determined in step 102 that the target yaw rate adaptation control or the target slip angle adaptation control is considered to be necessary, if the number of slip wheels Nslip is non-zero, that is, if any one of When it is determined that the wheel is slipping or showing the tendency (122), the process also shifts to TRC / ABS equivalent control (116).

An example of the procedure of TRC / ABS equivalent control is as follows.
As shown in FIG. When executing the TRC / ABS equivalent control, the vehicle control unit 38 firstly sets the coupling coefficient group according to the level of the wheel speed V of each wheel, the accelerator on / off, and the like.
A control constant group or the like is selected (400). The coupling coefficient group referred to here is a set of coefficients used for determining a threshold group used for angular acceleration determination described later, and the control constant group is a set of constants used for determining the feedback torque. It is. When the accelerator is on (402), the vehicle controller 38 determines (40) from the powering torque map according to the wheel speed V, the accelerator opening VA, and the shift position.
4) When the accelerator is off (402), a torque command is provisionally determined from the regenerative torque map according to the wheel speed V, the braking force FB and the shift position (406). Further, when the accelerator is on (402), the vehicle control unit 38 determines whether the accelerator opening VA
Based on the coupling coefficient group selected at 0 (408), and when the accelerator is off (402), based on the braking force FB and the coupling coefficient group selected at step 400 (410), a threshold group To determine.

The vehicle control unit 38 determines in step 408 or 4
The angular acceleration dω / dt of each wheel is classified based on the threshold group determined in 10 (412). Vehicle control unit 3
8 determines the feedback torque using a different arithmetic expression or the like according to the result of the classification. For example, when the wheel angular acceleration dω / dt belongs to the first range, the feedback torque determination processing by the first arithmetic expression is performed by (414-
1) When it belongs to the second range, the feedback torque determination processing based on the second arithmetic expression is (414-2), and when it belongs to the third range, the feedback torque determination processing based on the third arithmetic expression is (414-3). ..,... When belonging to the n-th range, the feedback torque determination processing based on the n-th arithmetic expression is determined according to the range to which the rotational angular acceleration dω / dt belongs for each wheel, such as (414-n). The feedback torque is determined by an arithmetic expression. Further, steps 414-1, 414-2, 414-3,.
.. The constants in the arithmetic expression relating to 414-n are determined in step 4
The value is related to the control constant group selected in 00. The vehicle control unit 38 determines the torque command value by subtracting the feedback torque determined in this manner from the torque command value provisionally determined in step 404 or 406 (416), and corresponds to the determined torque command value. Output to the motor control unit (418).

By adopting such a procedure,
The torque acting on each drive wheel can be appropriately changed within the range shown in FIG. 9 described above, and a function corresponding to TRC / ABS control in a conventional engine vehicle can be realized. If possible, hydraulic pressure may be used in the ABS equivalent control. Regarding TRC / ABS equivalent control, Japanese Unexamined Patent Application Publication No.
See also Japanese Patent Application No. 182119 and Japanese Patent Application No. 9-8693. After the procedure shown in FIG. 10 ends, the operation of the vehicle control unit 38 proceeds to step 106 shown in FIG.

The vehicle control unit 38 controls the conditions for shifting from the target yaw rate adaptation control to the target slip angle adaptation control and the TRC /
When none of the conditions for shifting to the ABS equivalent control are satisfied, that is, when the absolute value of the steering angle δt is not equal to or greater than the threshold value, the number Nslip of the slip wheels is equal to or less than 2, and the left two 4WD control 1 when none of the wheels or the two right wheels are slip wheels
Step 10 is performed.

At this time, the vehicle controller 38 first determines whether or not the number Nslip of the slip wheels is 1 (124). Since Nslip = 0 on a normal traveling road, the operation of the vehicle control unit 38 includes steps 126 and 12
Move to 8. In step 126, the vehicle control unit 38
Determines all drive wheels as distribution wheels. Here, the distribution wheels are drive wheels to which torque output is actually distributed. In step 128, the vehicle control unit 38 sets the specific gravity of the distribution of the torque output to each distribution wheel to a normal value.
For example, the specific gravity of distribution = 1 is set for all drive wheels. However, the specific gravity of this distribution may be changed according to the vehicle loading weight, or may be a predetermined specific gravity that differs between the front and rear wheels according to the structure of the vehicle body.

Conversely, at step 124, Nslip
= 1 or when it is determined in step 120 that the condition for shifting to the TRC / ABS equivalent control is not satisfied, the wheels other than the vehicle control unit 38 slip wheels are determined as the distribution wheels (130). ). Furthermore, the distribution specific gravity for each wheel is adjusted so that the moment in the yaw direction centering on the vehicle center of gravity does not act on the vehicle body when the torque is actually output, that is, the left and right sides are balanced (132). ). For example, the distribution specific gravity is set to 0 so that the torque command is not given to the drive wheels that are not selected as the distribution wheels in step 130, that is, the slip wheels, and the distribution specific gravity of the non-slip wheels to which the slip wheels belong out of the left side and the right side is set. Increases the distribution specific gravity corresponding to the torque output that would have been distributed to the slip wheels if it was not slipping.

The vehicle control unit 38 determines in step 128 or 1
32, if the accelerator is on (13
4) From the powering torque map according to the vehicle speed VS, the accelerator opening VA and the shift position (136), if the accelerator is off (134), the vehicle speed VS and the braking force FB
From the regenerative torque map according to the shift position and (1
38) Temporarily determine the torque command. After executing Step 136 or 138, the vehicle control unit 38 proceeds to Step 128.
Alternatively, the torque command value provisionally determined in step 136 or 138 is adjusted (for example, by multiplying by the distribution specific gravity) in accordance with the distribution specific gravity set or adjusted in advance at 132, whereby the torque command value for each wheel is adjusted. Is determined (140). The vehicle control unit 38 outputs each torque command value determined in step 142 to the corresponding motor control unit (142), and then proceeds to step 106.

Therefore, in this embodiment, the control state is switched according to the slip state of each wheel, as shown in FIG. First, when only one of the four wheels is slipping, that is, when Nslip = 1, as shown in FIG. 11 (a), if there is no slip, the wheel should be caused to slip. The torque command is output from the other drive wheels on the same side as the slip wheel. In FIG. 11, the slip wheels are indicated by right hatching. In addition, when Nslip = 2, as shown in FIG. 11 (b-1) or (b-2), when one slip wheel exists on each of the left and right sides, the left and right slip wheels are left one by one. The torque command is realized by the slip wheel. Further, as shown in FIG. 11 (b-3), when Nslip = 2 and all the slip wheels are on the left (or right), TRC / AB
S equivalent control is executed. Further, when Nslip = 3 as shown in FIG. 11 (c) or when Nslip = 4 as shown in FIG. 11 (d), TRC / ABS equivalent control is also executed.

As described above, according to the present embodiment, the control mode of each motor output by the vehicle control unit 38 and each wheel 4WD suitable for a wheel-in motor type four-wheel drive electric vehicle because the torque distribution specific gravity for
Control and TRC / ABS equivalent control can be realized to maintain and improve running stability.

Various modifications can be made to the vehicle speed detection procedure shown in FIG. For example, in the procedure shown in FIG. 12, two types of thresholds, Nslip and Nslip0, are used as variables for counting the number of slip wheels. The variable Nslip is a variable for counting the number of drive wheels whose absolute value of the wheel angular acceleration dω / dt exceeds the first threshold value (204A, 208A), and the variable Nslip0 is the wheel angular acceleration dω / This is a variable for counting the number of drive wheels whose absolute value of dt exceeds the second threshold value (20
4B, 208A, 208B). However, step 204
A and the first threshold used in 204B and the second threshold
Is set so as to satisfy first threshold value <second threshold value. Further, in the procedure of FIG.
In steps 214A and 216B corresponding to 16, Nslip is not determined whether or not Nslip is equal to 4.
It is determined whether lip0 is equal to 4 and VS =
VS = VS / instead of VS / (4-Nslip)
The vehicle speed VS is calculated using the equation (4-Nslip0). In this way, the number of slip wheels (Nslip) used for determination in the procedure of FIG. 4 and the number of drive wheels (Nslip0) excluded from the calculation base of the vehicle speed when detecting the vehicle speed are different values. Can be This increases the degree of freedom in design. FIG.
May be modified as shown in FIG.
In the vehicle body speed detection procedure shown in FIG. 13, step 206 is also executed for the drive wheels for which the determination condition that the wheel angular acceleration dω / dt is larger than the threshold value is satisfied. Further, in step 216B corresponding to step 216 in the procedure of FIG.
The drive wheels determined to be statistically excluded in the above are excluded from the basis of the vehicle body speed calculation. That is, in step 222, among the wheels whose wheel speed V has been added to the variable VS in step 206, a wheel having a wheel speed V to be statistically excluded, for example, a large difference from the wheel speeds of the other wheels. Are detected, and in step 216B, the wheel speed of the wheel that is detected to be excluded is subtracted from the variable VS and divided by the number of drive wheels excluding the wheel. , The vehicle speed VS is calculated. Similar effects can be obtained by such a method.

[0033]

According to the first configuration of the present invention, when at least one non-slip wheel is provided on each of the left and right sides of the vehicle body, adjustment is made so that a new yaw direction moment does not act on the vehicle body. Thus, since the output torque value is instructed to each motor, mWD can be realized while preventing generation of the yaw direction moment, and highly reliable running stability control at the time of slip can be realized.

According to the second configuration of the present invention, when there is no non-slip wheel on the left side of the vehicle body and when there is no non-slip wheel on the right side, the non-slip wheel is adjusted according to the slip state of the slip wheel. Since the output torque value is instructed to each motor, the TRC / ABS equivalent control can be realized without a member for operating the pressure of the braking fluid, and the TRC / ABS equivalent control operates under appropriate conditions. Therefore, highly reliable running stability control at the time of slip can be realized.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a system configuration of an electric vehicle suitable for carrying out the present invention.

FIG. 2 is a cross-sectional view showing an example of the structure of a wheel-in motor, and a circle in the upper right in the figure is a partially enlarged view.

FIG. 3 is a diagram showing a braking force distribution in the system of FIG. 1;

FIG. 4 is a flowchart illustrating an operation procedure of a vehicle control unit.

FIG. 5 is a flowchart illustrating an example of a vehicle speed detection procedure.

FIG. 6 is a flowchart illustrating an example of a target yaw rate (slip angle) adaptation control procedure.

FIG. 7 is a diagram illustrating an example of a powering torque map.

FIG. 8 is a diagram showing an example of a regenerative torque map.

FIG. 9 is a diagram showing a torque output range.

FIG. 10 is a flowchart showing an example of a TRC / ABS equivalent control procedure.

11A and 11B are diagrams showing switching of a control method and setting of distribution specific gravity according to the position and the number of slip wheels in this embodiment. FIG. 11A particularly shows a case where one of four wheels slips. , (B-1) to (b-3) show when two wheels slip, (c) show when three wheels slip, and (d) show when four wheels slip. , Respectively.

FIG. 12 is a flowchart illustrating another example of a vehicle body speed detection procedure.

FIG. 13 is a flowchart illustrating another example of a vehicle body speed detection procedure.

[Explanation of symbols]

10FR right front wheel, 10FL left front wheel, 10RR right rear wheel, 10RL left rear wheel, 12FR, 12FL, 12R
R, 12RL motor, 32 battery, 34FR, 3
4FL, 34RR, 34RL inverter, 36FR,
36FL, 36RR, 36RL Motor control unit, 38
Vehicle control unit, 40FR, 40FL, 40RR, 40RL
Rotation sensor, V, VFR, VFL, VRR, VRL
Wheel speed, VS body speed, Nsilp, Nslip0 Number of slip wheels, TFR, TFL, TRR, TRL Torque command.

Claims (2)

[Claims] 1. m driving wheels (m is a natural number of 3 or more) each of which is rotationally driven by an output torque of a corresponding motor.
In the drive control device mounted on the electric vehicle having the above and instructing an output torque value to each motor, a slip for discriminating each drive wheel into a slip wheel and a non-slip wheel depending on whether the current slip or the tendency is occurring. When the wheel detecting means and at least one non-slip wheel are on the left and right sides of the vehicle body, an adjustment is made so that a new yaw direction moment does not act on the vehicle body. And an m-wheel drive control means. 2. The number of driving wheels (m is a natural number of 3 or more) each of which is rotationally driven by the output torque of a corresponding motor.
In the drive control device mounted on the electric vehicle having the above and instructing an output torque value to each motor, a slip for discriminating each drive wheel into a slip wheel and a non-slip wheel depending on whether the current slip or the tendency is occurring. When there is no wheel detection means and no non-slip wheel on the left side of the vehicle body and when there is no non-slip wheel on the vehicle body, the output torque value is adjusted for each motor after the adjustment according to the slip state of the slip wheel. And a TRC / ABS equivalent control means for instructing.