JPH09117016A - Drive system for electric automobile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prolong the run range by varying the allocation of torque through the operation of a steering wheel thereby suppressing power consumption of a battery. SOLUTION: A left/right wheel torque command circuit 7 receives a steering force (a) from a steering wheel 6 along with an accelerator opening (b) and vehicle speed information (c). Based on these data, the left/right wheel torque command circuit 7 determines correction values (f), (g) for obtaining a torque command value optimal to left/right drive inverters 8, 9. Motors 3, 4 are fed with torque command values (d), (e) of right/left wheels through the drive inverters 8, 9 along with the correction values (f), (g). Since the steering force (a) is fed to the left/right wheel torque command circuit 7 when the steering wheel 6 is disconnected, an effect similar to power steering can be attained by varying the correction values (f) (g) thereby varying the allocation of motor torque between left and right front wheels.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a drive system for an electric vehicle.

[0002]

2. Description of the Related Art A conventional electric vehicle steering system is shown in FIG. As shown in the figure, in the conventional case, the front wheel 0
1, 02 are driven by left and right separate motors 03, 04, and an electric (or hydraulic) power steering 05 (electric motor) is adopted. When the steering wheel 06 is turned off, the left and right front wheels 01, 02 Give the same torque.

[0003]

In the above-mentioned conventional electric vehicle, since the electric (or hydraulic) power steering system is used, extra battery power is consumed. Therefore, the conventional electric vehicle has a problem that the traveling distance is reduced.

[0004]

A drive system for an electric vehicle according to the present invention, which solves the above-mentioned problems, changes left and right torque distribution by steering a steering wheel in an electric vehicle in which front wheels are driven by separate left and right motors. It is characterized by Further, a drive system for an electric vehicle according to the present invention which solves the above-mentioned problems, in an electric vehicle in which front wheels are driven by left and right separate motors, increases or decreases the torque according to the vehicle speed, reduces the steering force in low speed traveling, and travels in high speed. Is characterized by making the steering force heavy.

Further, in the electric vehicle drive system of the present invention which solves the above-mentioned problems, in an electric vehicle in which the front wheels are driven by separate right and left motors, the motor is provided with a torque proportional to the accelerator opening and a steering force. It is characterized in that a torque is generated by adding a torque determined by a value obtained by multiplying the vehicle speed constant. It can be applied to an electric vehicle in which four wheels are driven by different motors or an electric vehicle in which rear wheels are driven by different motors.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will now be described in detail with reference to the embodiments shown in the drawings. 1 to 4 show a drive system of an electric vehicle according to an embodiment of the present invention.
As shown in FIG. 2, this embodiment is applied to an electric vehicle in which front wheels 1 and 2 are driven by left and right motors 3 and 4, respectively.

Further, in this embodiment, as shown in FIG.
Left and right wheel torque command circuits 7 and drive inverters 8 and 9 are provided. To the left and right wheel torque command circuit 7, the steering wheel steering force a is input from the steering wheel 6, while the accelerator opening b and the vehicle speed information c are input.

The left and right wheel torque command circuit 7 obtains correction values f and g based on these data so as to obtain optimum torque command values for the left and right drive inverters 8 and 9. The correction values f and g are added to the motors 1 and 2 via the drive inverters 8 and 9 together with the torque command values d and e for the right and left wheels and input.

Therefore, in the present embodiment, when the steering wheel 6 is turned off, the steering force a is input to the left and right wheel torque command circuit 7. Therefore, by changing the correction values f and g, the motor 3, By changing the torque distribution of the left and right front wheels 1 and 2 by 4, it is possible to obtain the same effect as the power steering. Further, since the vehicle speed information c is also input to the left and right wheel torque command circuit 7, the torques of the motors 3 and 4 are controlled according to the vehicle speed so that the steering force is light at low speed traveling and heavy at high speed traveling. It can also be controlled according to the vehicle speed.

Further, according to the following equation (1), a torque obtained by adding a torque proportional to the accelerator opening b to the left and right motors 3 and 4 and a torque determined by a value obtained by multiplying the steering steering force a by the vehicle speed coefficient is obtained. By generating it, it is possible to provide the same function as the vehicle speed sensitive power steering. Motor torque = accelerator opening degree + steering steering force x vehicle speed coefficient (1)

Here, the vehicle speed coefficient is a coefficient that becomes maximum at a vehicle speed of 0 and becomes smaller as the vehicle speed increases, as shown in FIG. Further, as shown in FIG. 3, “±” in the above equation (1) indicates that the “-” indicates the motor torque in the steering turning direction, and the “+” indicates the motor torque in the opposite direction. Is shown.

As described above, in this embodiment, the motors 3, 4 are
By changing the torque distribution of 1, it is possible to obtain the same effect as the power steering, and as shown in FIG. 2, an electric (or hydraulic) power steering system becomes unnecessary. As a result, the present embodiment has an advantage that the battery power consumption is suppressed and the traveling distance is increased.

The present invention is not limited to the above embodiment, but can be applied to an electric vehicle in which four wheels are driven by different motors or an electric vehicle in which rear wheels are driven by different motors. It shows the same effect.

[0014]

As described above in detail with reference to the embodiments, the electric vehicle drive system according to the present invention exhibits the same function as that of the power steering. Therefore, the electric or hydraulic power steering system is used. Is unnecessary. As a result, there is an advantage that the consumption of battery power is suppressed and the traveling distance is extended. Further, the present invention can be widely applied to rear-wheel drive vehicles and four-wheel drive vehicles.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a drive system of an electric vehicle according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing a drive system of an electric vehicle according to an embodiment of the present invention.

FIG. 3 is an explanatory diagram showing steering of a steering wheel.

FIG. 4 is a graph showing the relationship between vehicle speed and vehicle speed coefficient.

FIG. 5 is a schematic diagram showing a conventional steering system for an electric vehicle.

[Explanation of symbols]

 1, 2 front wheels 3, 4 motor 6 steering wheel 7 left and right wheel torque command circuit 8, 9 drive inverter

Claims (5)

[Claims] 1. In an electric vehicle in which the front wheels are driven by separate left and right motors, steering wheel steering
A drive system for an electric vehicle, which is characterized by changing the left and right torque distribution. 2. An electric vehicle in which front wheels are driven by separate left and right motors, the torque is increased or decreased according to the vehicle speed, the steering force is lightened at low speed running, and the steering force is heavy at high speed running. Car drive system. 3. An electric vehicle in which front wheels are driven by separate right and left motors, and a torque obtained by adding to the motor a torque proportional to an accelerator opening and a torque determined by a value obtained by multiplying a steering steering force by a vehicle speed constant. A drive system for an electric vehicle, which is characterized by being generated. 4. The drive system for an electric vehicle according to claim 1, which is applied to an electric vehicle in which four wheels are driven by separate motors. 5. The drive system for an electric vehicle according to claim 1, which is applied to an electric vehicle in which rear wheels are driven by separate motors.