JPH0685601B2 - Driving force control device for electric vehicle - Google Patents

Description

The present invention relates to a driving force control device for an electric vehicle,
More specifically, the present invention relates to a driving force control device for an electric vehicle that drives a pair of left and right driving wheels with separate motors.

[Conventional technology and its problems]

Generally, in order to maximize the driving performance of the vehicle,
As a general rule, it is necessary that the driving force on the left and right is the same for both straight running and turning. However, if one of the left and right drive wheels slips due to freezing roads, depressions, muddy areas, etc., the above-mentioned principle of left and right equal drive force cannot be applied, and control that weakens the drive force of the idle wheel (traction control) Is required.

By the way, an electric vehicle in which a pair of left and right drive wheels are driven by separate motors is known mainly for the purpose of omitting the steering wheels and the actuator. This type of electric vehicle is suitable for traction control, and various control systems have been proposed for the purpose of the above control.

As this traction control method, there is an "electric vehicle control method" (Japanese Patent Laid-Open No. 60-32501) which prevents the drive wheels of an electric vehicle from idling or sliding. This control method is
As shown in FIG. 2, in an electric vehicle in which the left and right drive wheels are driven by separate electric motors, the left and right drive motors 73L and 73R are
It is driven by controlling the electric power of 71 with thyristors 72L and 73R. Next, the rotation detectors 74L, 7 of each motor 73L, 73R
The signal from 4R enters low value priority circuit 75 and comparison circuits 76L and 76R. As a result, (higher rotation speed-lower rotation speed)
The signal ΔN of the rotation speed difference of the idle torque controller 77L, 77R
Enter either. The speed difference between the left and right wheels when idling does not occur in this electric vehicle is a constant value Ns determined by the wheel position and the turning radius. The idling torque controller determines that idling has occurred when ΔN exceeds Ns, weakens the torque signal commanded by the accelerator 80 by an excess amount (ΔN-Ns), and inputs the weakened torque signal to the speed regulator 78L or 78R. Then, this signal is sent to the thyristor 72 via the ignition angle adjusters 79L and 79R.
Controls L and 72R. Therefore, when the rotational speed difference between the left and right drive wheels exceeds a predetermined value, the drive wheel with the higher rotational speed is weakened, and idling is suppressed.

However, in this conventional electric vehicle control system,
When the difference between the left and right rotational speeds becomes larger than a predetermined value, it is determined that the vehicle is idling, and therefore simultaneous idling of the left and right cannot be detected. Also,
There is a problem that it cannot be dealt with when the rotational speed difference becomes smaller than a predetermined value, such as when the inner wheel spins during turning drive. Further, in a general electric vehicle, the same driving force command is given to the left and right wheels at the time of turning, so the inner wheel having the smaller slip limit driving force slips first, and the command driving force of the inner wheel is weakened from that point. Therefore, the driving force combined with both wheels cannot be maximized, and the slip ratio control is started earlier, so that the driving force is turned on and off more frequently and the drive feeling is deteriorated.

Therefore, the inventors of the present invention have earnestly studied in order to solve the above-mentioned problems of the prior art, and as a result of various systematic experiments, the present invention has been accomplished.

[Object of the Invention]

An object of the present invention is to detect and suppress the left and right wheels idling under any circumstances at any timing, and at the same time, it is possible to give maximum driving force to each of the inner and outer wheels when turning. An object of the present invention is to provide a driving force control device for an electric vehicle that can easily turn even with a small turning radius.

With respect to the above-mentioned problems of the conventional technique, the present inventors consider the change of the vehicle load at the time of turning, and give different torque commands to the motors of the inner and outer wheels, thereby solving the main problems of the above-mentioned conventional technique. I focused on solving it.

[Explanation of the Invention]

The drive force control device for an electric vehicle according to the present invention is a device for controlling the drive force of an electric vehicle as shown in FIG. 1, in which the left and right drive wheels 61, 62 of the vehicle are driven by separate motors. In the force control device, at least one vehicle speed sensor 11 for detecting the speed of the vehicle, at least one rotation speed sensor for detecting the rotation speed of the drive wheels of the vehicle, and at least one for each of the left and right drive wheels in the previous period are provided to the drive wheels of the vehicle. A load sensor 13 for detecting such a load, an accelerator angle sensor 14 for detecting an accelerator opening, a vehicle speed signal output from the vehicle speed sensor 11 and a rotation speed signal output from the rotation speed sensor 12 are used to drive wheels. A slip detecting means 20 for calculating a slip ratio (idling ratio) of and outputting a driving force correction signal,
Necessary for correcting and controlling the driving force of the vehicle based on the driving force correction signal output from the slip detecting means 20, the load signal output from the load sensor 13 and the accelerator angle signal output from the accelerator angle sensor 14. Driving force and /
Alternatively, a motor control amount calculation means 30 for calculating a control amount commensurate with the braking force according to the drive wheel load of the vehicle and outputting a control amount signal for each drive wheel, and a control amount output from the motor control amount calculation means 30. First motor control device 41 for adjusting the electric power supplied to the motor based on the motor command signal as a signal
And a second motor control device 42, and the first motor control device
41 and a drive means 40 including a power supply source 43 connected to the second motor control device 42 to supply electric power to the motor, and based on the electric power controlled by the drive means 40, the shaft of the left drive wheel 61 A first motor 51 for continuously variably controlling the torque, and a second motor 52 for continuously variably controlling the torque of the shaft of the right drive wheel 62 based on the electric power controlled by the drive means 40. It is characterized by.

The operation and effect of the present invention having the above configuration are as follows. That is, according to the present invention, in the driving force control device for an electric vehicle in which the left and right driving wheels of the vehicle are driven by separate motors, first, the vehicle speed sensor 11 detects the vehicle speed and converts it into an electric signal corresponding to the vehicle speed. Further, the rotation speed sensor 12 detects the rotation speed of the drive wheels of the vehicle and converts it into an electric signal corresponding to the rotation speed. Also,
At least one is provided for each of the left and right drive wheels, and the load sensor 13 detects the load applied to the drive wheels of the vehicle and converts the load into an electrical signal corresponding to the load.
Further, the accelerator angle sensor 14 detects the opening degree of the accelerator and converts it into an electric signal or the like corresponding to the accelerator angle.

Then, from the vehicle speed signal output from the vehicle speed sensor 11 and the rotational speed signal output from the rotational speed sensor 12, the slip detection means 20 obtains the slip ratio (idling ratio) of the drive wheels of the vehicle from the rotational speed signal. The difference between the peripheral speed of the drive wheel and the vehicle speed is calculated by dividing the peripheral speed of the drive wheel, and a driving force correction signal is output as a target value for the correction control.

Then, in the motor control amount calculation means 30, from the driving force correction signal output from the slip detection means 20, the load signal output from the load sensor 13, and the accelerator angle signal output from the accelerator angle sensor 14, The control amount commensurate with the driving force and / or the braking force necessary for correcting and controlling the driving force of the vehicle, that is, the torque required for the first motor 51 and the second motor 52 is calculated to obtain the driving wheel load. A corresponding torque command signal is output.

Then, based on the motor command signal output from the motor control amount calculation means 30, the drive means 40 adjusts the electric power supplied to the motor by the first motor control signal 41 and the second motor control device 42, and then, In the first motor 51 and the second motor 52, respective shafts of the drive wheels 61 and 62 are generated so as to generate a control force according to the states of the drive wheels 61 and 62 of the electric vehicle and follow the drive force. Torque is continuously variable controlled.

The power supply source 43 of the driving means 40 is connected to the first motor control device 41 and the second motor control device 42 to supply electric power to the motor.

With the above configuration, the driving force control device for an electric vehicle according to the present invention weakens the driving force individually based on the slip ratios calculated individually for the left and right driving wheels. Even if it spins under such a situation, it can be detected and suppressed. In addition, by detecting the load movement during turning and issuing a small driving force to the inner wheels with low slip limit driving force and a large driving force to the outer wheels with high slip limit driving force, the inner and outer wheels during turning are commanded. Since the maximum driving force can be applied to each of them, it is possible to turn at a higher speed on a road having a low friction coefficient and to easily turn even with a small turning radius. In addition, when increasing the driving force, it is delayed that the inner wheel started to slip earlier in the past, so the frequency of slip prevention control is reduced and the deterioration of drive feeling is minimized. You can

[Description of Other Inventions] With regard to other inventions relating to the control method applicable to the driving force control device of the present invention, the basic idea thereof will be briefly described with reference to FIG. 3 and FIG. Explained. First, 1) When traveling straight ahead The motor control amount computing means 30 uniformly issues a driving force [Fig. 4 (a)] substantially proportional to the accelerator angle / brake angle to the left and right motors. The driving force f is obtained by the following equation from the driving force coefficient μ and the vertical load W applied to the driving wheels.

f = μW (1) The driving force coefficient μ is determined by the friction coefficient of the road surface, the slip ratio of the tire, etc., and has a maximum value μm at a certain slip ratio. Therefore, the maximum value fm (= μmW) also exists in the driving force, and slip occurs when the accelerator is depressed beyond the accelerator angle θm corresponding to fm. As a result, the slip detection means 20 outputs the corrected driving force signal. When this signal is generated, the motor control amount calculation means 30 calculation means weakens the driving force command value accordingly.

That is, when accelerator angle θ ≦ θm, Kt is taken as a proportional constant, and f _L ^* = F _R ^* = Kt θ (2) Kt is the maximum driving force f′m and the maximum accelerator angle θ′m on a high friction road surface. On the other hand, Kt = f'm / θ'm (3) is preset.

When θm <θ, the driving force command corresponding to the corrected driving force
f _L ^*, a command weakening the f _R ^*.

As a result, when the slip stops, the driving force command increases to the value determined by the equation (2). It is difficult to know fm itself, but by repeating the increase and decrease described above, as a result, f _L ^* = f _R ^* ≈ fm (4).

2) During turning, the driving force coefficient changes with a large load change. However, within the range of load change where the influence on the driving force coefficient can be ignored, the limiting driving force fm is the driving force load Wi, W ₀ , the limiting driving force of the inner and outer wheels is fim, and f ₀ m is Like

fim = μW i (5) f ₀ m = μW ₀ (6) That is, the limit driving force is large for the outer ring and small for the inner ring due to load movement. In response to this, the left and right motor control amount calculation means 30, as shown in FIG. 4 (b), with respect to the accelerator angle θt, ft ₀ ^* = Kto · θt (7) fti ^* = Kti · θt. Outputs a torque command such that (8). Kto and Kti are
The following is obtained from (1), (2), (5), and (6).

Kto = (W ₀ / W) Kt …… (9) Kti ＝ (Wi / W) Kt …… (10) W is the wheel load on the left and right when going straight, W ≒ (W ₀ + Wi) / 2
Is.

Then, the torque command of the inner and outer rings fto ^*, to convert the fti ^* torque command of the left and right wheels ft _L ^*, a ft _R ^*.

Now, assuming that the outer wheel is the left wheel, W ₀ = W _L , Wi = W _R , W = (W _L + W _R ) / 2 Here, if W _L -W _R = 2ΔW (13) W _L -W _R = 2W (14), then Eqs. (11) and (12) are as follows.

In the above, the left wheel is assumed to be the outer wheel for turning, but the sign of ΔW in Eq. (13) is inverted even if the right wheel is the outer wheel, so the above conversion equation holds.

Therefore, if the wheel loads W _L and W _R are known, the command torque for driving can be determined from the equations (13) to (16).

Wheel load is a load sensor 13 built into the suspension spring of the drive wheel.
Measure with L and 13R.

Even when turning, by the signal of the slip detection means 20,
As in the case of going straight, the command torque is saturated corresponding to the limit driving forces f ₀ m and fim above a certain accelerator angle [Fig. 4 (b)].

Next, the slip detecting means 20 inputs the signals of the vehicle speed sensor 11 and the rotational speed sensors 12L and 12R of the left and right driving wheels, and outputs a slip signal to the motor control amount calculating means as described below.

When, the slip signal is generated, λ is a slip ratio, and λ = 0.2 to 0.3 is selected.

Next, in the motor control system of the driving means 30, the torque command
When f _L ^* and f _R ^* are input to the first motor control device 41 and the second motor control device 42, the normal PWM (pulse width control) is performed from the power supply source 43 to the first motor 51 and the second motor control device 42. The electric power supplied to the motor 52 is controlled, and the vehicle runs while following the command driving forces f _L ^* and f _R ^* .

By doing so, the slips of the left and right wheels during driving are separately detected, and the optimum torque command is given to each drive motor. Therefore, when both wheels slip or lock at the same time, or when the inner wheel slips and the outer wheel locks such that the rotational speed difference between the two wheels becomes smaller during turning, slip prevention should be performed according to the accelerator signal. You can

Further, conventionally, as shown in FIG. 4 (c), since the same command value is output for both the inner and outer wheels, the command driving force f ₀ ^* of the outer wheel is the limit driving force at θm ″ which is larger than the slip limit accelerator angle θm when going straight. f ₀ m is reached, and the command drive force fi ^* of the inner wheel reaches the limit drive force fim at an accelerator angle θm ′ smaller than θm.
The total driving force f ₀ ^* + fi ^* is such that the accelerator angle θ is θm ′ ≦ θ ≦
During θ ′, it becomes smaller than the drive force that can be originally generated. On the other hand, in the present control method, the command drive force is controlled so that the inner wheel is small and the outer wheel is large according to the movement of the wheel load during turning. That is, as illustrated in FIG. 4 (b), since f ₀ ^* reaches f ₀ m and fi ^* reaches fim in the vicinity of the accelerator angle θm, the total driving force is kept close to the slip limit. This makes it possible to turn at a higher speed than before on a frozen road with a low coefficient of friction, etc. Also, the accelerator angle at which slip prevention control starts is θm ′ → θ.
Since it is increased to m, the frequency of the slip prevention control is reduced. Ordinary anti-slip control is accompanied by an increase / decrease in motor torque, so it is inevitable that the drive feeling will deteriorate to some extent, but the frequency of anti-slip control will decrease, and this deterioration in drive feeling will be minimized. effective. Further, as an additional effect, since a moment in a direction that promotes turning acts on the vehicle body due to the difference in driving force between the inner and outer wheels, turning with a small radius is particularly easy.

〔Example〕

First Embodiment A driving force control device for an electric vehicle according to a first embodiment of the present invention will be described with reference to FIG.

As shown in FIG. 5, the drive force control device for an electric vehicle according to the present embodiment includes a vehicle speed sensor 11, rotational speed sensors 12L and 12R,
Load sensors 13L, 13R, accelerator angle sensor 14, slip detection means 20, motor control amount calculation means 30, and drive means 40
And a first motor 51 and a second motor 52.

The vehicle speed sensor 11 detects the speed of the vehicle, is composed of a tacho generator, and is incorporated in a transmission (not shown).

The rotation speed sensors 12L, 12R detect the rotation speed of the drive wheels of the vehicle, and the encoders 121, 1 incorporated in the motor shaft are used.
22 and signal processing circuits 123 and 124 for integrating the output pulse and converting it into an analog value.

The load sensors 13L and 13R detect the load applied to the drive wheels of the vehicle, and are composed of load cells incorporated in suspension springs of the drive wheels.

The accelerator angle sensor 14 detects the opening degree of the accelerator, and is composed of a potentiometer incorporated in the carburetor of the engine.

The slip detecting means 20 includes amplifiers 211 and 212 and a subtractor 22.
1, 222, dividers 231, 232 and comparators 241, 242.

The amplifiers 211 and 212 are connected to the rotation speed sensors 12L and 12R,
Left and right wheel speed signals ω _L and ω _R output from the sensor
Are amplified r times (wheel radius times) and the amplified signal is output.

Subtractors 221, 222 are connected to amplifiers 221, 212,
The vehicle speed signal v output from the vehicle speed sensor 11 is subtracted from the amplified signal output from the amplifier.

The dividers 231, 232 include subtractors 221, 222 and amplifiers 211, 2
The slip ratios λ _SL and λ _SR are calculated by dividing the subtracted signals output from the subtractors 221 and 222 and the amplified signals output from the amplifiers 221 and 212, respectively.

The comparators 241 and 242 are connected to the dividers 231 and 232, respectively, and the signals λ _SL and λ output from the dividers 231 and 232, respectively.
_{When SR} exceeds λ (0.2 to 0.3), f _SL and f _SR (both are positive numbers smaller than the maximum driving force of each wheel, for example, 50k
When g) does not exceed the value, 0 is output as a correction driving force signal.

The control amount calculation means 30 includes adders 311, 312 and subtractors 321, 3
22, 323, 324, multiplier 331, divider 341, and amplifier 35
It consists of 1, 352 and 353.

The adder 311 is connected to the load sensors 13L and 13R and adds the wheel load signals W _L and W _R output from the sensors.

The subtractor 321 is connected to the load sensors 13L and 13R and subtracts W _R from the wheel load signal W _L output from the sensors.

The amplifier 351 is connected to the adder 311 and outputs the signal W by halving the signal output from the adder 311 (the above (1
Equivalent to equation 4)). Further, the amplifier 352 is connected to the subtractor 321 and multiplies the signal output from the subtractor 321 by 1/2 to output the signal ΔW (corresponding to the above equation (13)).

The divider 341 is connected to the amplifiers 351 and 352, and the amplifier 3
The signal ΔW output from 52 is divided by the signal W output from the amplifier 351, and the signal ΔW / W is calculated.

The amplifier 353 is connected to the accelerator angle sensor 14, multiplies the signal θt output from the sensor by Kt, and outputs a signal Kt · θt.

The multiplier 331 is connected to the amplifier 353 and the divider 341, multiplies the signal output from the amplifier 353 by the signal output from the divider 341, and outputs a signal Kt · θt · ΔW / W.

The adder 312 is connected to the amplifier 353 and the multiplier 331, and adds the signal Kt · θt output from the amplifier 353 and the signal Kt · θt · ΔW / W output from the multiplier 331 to obtain ft _L ^* . Output (corresponding to equation (15) above).

The subtractor 322 is connected to the amplifier 353 and the multiplier 331 and subtracts the signal Kt · θt output from the amplifier 353 and the signal Kt · θt · ΔW / W output from the multiplier 331 to obtain ft _R ^* . Output (corresponding to equation (16) above).

The subtractor 233 is connected to the adder 312 and the comparator 241 of the slip detection means 20 and outputs the signal output from the adder 312.
The signal f _SL output from the comparator 241 is subtracted from ft _L ^* to output f _L ^* .

The subtractor 324 is connected to the adder 322 and the comparator 242 of the slip detecting means 20, and outputs the signal output from the adder 312.
The signal f _SR output from the comparator 241 is subtracted from ft _R ^* to output f _R ^* .

The driving means 40 is a first motor control device (left) 41 and a second motor control device (right) which are PWM type choppers.
42, a power supply source 43, and a triangular wave generation circuit 44 that outputs a high frequency modulation signal.

The first motor control device 41 is connected to the subtractor 323 of the motor control amount calculation means 30 and the triangular wave generation circuit 44, and subtracts the modulation signal output from the circuit 44 from the signal f _L ^* output from the subtractor 323. Subtractor 411 for subtraction, and a zero-cross that outputs a high level signal when the signal output from the subtractor 411 is positive and a low level signal when the signal output from the subtractor 411 is negative. a comparator 412, connected via the zero-cross comparator 412 and drive circuit B _L, to adjust the average power supplied to the first motor 51 by repeating the on and off according to a signal of the drive circuit B _L It consists of a power transistor switch 413.

The second motor control device 42 is connected to the subtractor 324 of the motor control amount calculation means 30 and the triangular wave generation circuit 44, and subtracts the modulation signal output from the circuit 44 from the signal f _R ^* output from the subtractor 324. Subtractor 421 for subtraction, and a zero-cross connected to the subtractor 421 and a drive circuit (not shown) to output a high level signal when the signal output from the subtractor 421 is positive and a low level signal when the signal is negative. a comparator 422, connected via the zero-cross comparator 422 and drive circuit B _R, to adjust the average power supplied to the second motor 52 by repeating the on and off according to a signal of the drive circuit B _R It consists of a power transistor switch 423.

The power supply source 43 is composed of a battery that is connected to the first motor control device 41 and the second motor control device 42 and supplies power to the motors 51 and 52 via the transistor units 413 and 423 in series.

The first motor 51 is connected to the left drive wheel (not shown),
The torque of each shaft of the drive wheels is continuously variably controlled based on the electric power controlled by the drive means 40.

The second motor 52 connects to the right drive wheel (not shown),
The torque of each shaft of the drive wheels is continuously variably controlled based on the electric power controlled by the drive means 40.

The operation and effect of this embodiment having the above configuration are as follows.

1) When traveling straight ahead Since there is no load movement due to rolling of the vehicle body when traveling straight ahead, ΔW≈0. Therefore, the outputs of the divider 341 and the multiplier 331 are zero, and the outputs of the adder 312 and the subtractor 322 are ft _L ^* = ft _R ^* = Kt · θt.

If all the outputs of the slip detecting means 20 are zero, Kt · θt is output to the driving means 40 as the motor torque command values f _L ^* and f _R ^* . In the driving means 40, the switching operation of the power transistor switches 413 and 423 causes f _L ^* ,
Since a voltage substantially proportional to f _R ^* is applied to the first motor 51 and the second motor 52, the vehicle runs with equal driving force or braking force on the left and right in proportion to the accelerator angle θt.

When these driving forces exceed a limit value determined by the friction coefficient between the road surface and the tire, slip occurs. At this time, the slip ratio λs is calculated by the subtracters 221 and 222 and the dividers 231 and 232 from the vehicle speed and the rotational speed of the wheels for each of the left and right wheels, and the comparators 241 and 242 compare the slip ratio λs with the limit slip ratio λ.
When λs> λ, it is determined that the slip occurs, and the comparators 241 and 242 output the correction driving forces f _SL and f _SR for slip control. This corrected driving force is output to
Since it is subtracted from ft _L ^* and ft _R ^* , the driving force of the motor weakens and the slip stops. The slip disappears, the driving force ft ^*, recover to ft _R ^*. By repeating such a process, the average driving force is maintained near the limit value. In this way, the characteristics as shown in FIG. 4 (a) can be realized. Note that when it is not desirable to perform the slip correction too frequently, the comparators 241, 242
It is advisable to give some hysteresis characteristics.

2) During turning travel During turning travel, rolling of the vehicle body causes a load movement ΔW from the inner wheel to the outer wheel. When the outer wheel is the left wheel, ΔW>
It is 0. Load change rate ΔW / W is added to adder 311, subtractor 321,
The operation is performed by the amplifiers 351 and 352 and the divider 341. Further, by the multiplier 331, the adder 312, and the subtractor 322, the above (1
Execute the operation corresponding to the equations (5) and (16) and set the command value f
Outputs t _L ^* and ft _R ^* . The outer ring (f
t _L ^* ) is large by an amount proportional to ΔW, and the inner ring (ft _R ^* )
Is commanded small. When a slip occurs, the same control as when going straight is performed, so that the characteristics shown in FIG. 4 (b) can be realized.

Thus, the vehicle equipped with the device of the present embodiment separately detects the slip of the left and right wheels during driving, and gives an optimum torque command to each drive motor, so that when both wheels slip or lock at the same time, or When slipping of the inner wheel and locking of the outer wheel occur such that the difference in the number of rotations of the two wheels becomes small during turning, slip prevention can be executed according to the accelerator signal.

Further, the device of the present embodiment controls the command driving force so that the inner wheel is small and the outer wheel is large in accordance with the movement of the wheel load during turning, that is, as illustrated in FIG. 4 (b),
Since the control is performed so that f ₀ ^* reaches f ₀ m and fi ^* reaches fim in the vicinity of the accelerator angle θm, the total driving force can be increased to near the slip limit. As a result, it is possible to turn at a higher speed than before on a frozen road having a low friction coefficient. Further, since the accelerator angle at which the slip prevention control starts is increased from θm ′ to θm, the frequency of the slip prevention control is reduced. As a result, the normal slip prevention control is accompanied by an increase / decrease in the motor torque, and therefore the drive feeling is inevitably deteriorated. However, in the case of the present embodiment, the effect of minimizing the deterioration of the drive feeling is obtained. is there. Further, as an additional effect, since a moment in a direction that promotes turning acts on the vehicle body due to the difference in driving force between the inner and outer wheels, turning with a small radius is particularly easy.

Second Embodiment A driving force control device for an electric vehicle according to a second embodiment of the present invention will be described with reference to FIG.

In this embodiment, in the driving force control device for an electric vehicle of the first embodiment, the steering angle signal obtained from the steering angle sensor 15 is further input to the motor control amount calculation means 30, and the steering angle signal is also taken into consideration. In this way, an appropriate motor control amount can be obtained.

Hereinafter, the difference from the first embodiment will be described in detail.

First, the steering angle sensor 15 is composed of a potentiometer and is mounted coaxially with the steering wheel to measure the steering angle of the steering wheel.

Next, the control amount calculation means 30 includes the adders 311 and 312 and the subtractor.
321, 322, multiplier 331, divider 341, and amplifiers 351, 3
In addition to 52 and 353, an absolute value circuit 361 and a comparator 36
2 and an input signal changeover switch 363.

The steering angle signal δs output from the steering angle sensor 15 is
It is input to the control terminal of the input signal changeover switch 363 via the absolute value circuit 361 and the comparator 362. The input signal changeover switch 363 inputs the output of the divider 341 to one terminal H and grounds the other terminal L. Then, when a high level signal is input to the control terminal of the input signal changeover switch 363, it is switched to the H input, and when a low level signal is input, it is switched to the L input.

As a result, when traveling straight ahead, δs = 0, the output of the comparator 362 becomes low level, and the input of the input signal changeover switch 363 is on the L side. Therefore, the signal corresponding to the load movement amount ΔW is ignored. Therefore, in this case, the driving force command ft ^* is determined only by the accelerator angle θt.

Further, when turning, since δs ≠ 0, the input of the input signal changeover switch 363 is on the H side, and the same control as in the first embodiment is executed.

By doing so, the driving force control device for the electric vehicle according to the present embodiment has the effects of the driving force control device for the electric vehicle according to the first embodiment, and further has the following effects.

That is, in such an electric vehicle, there may be a difference in the left and right wheel loads when the vehicle runs straight depending on the position of the occupant, the load, and the like. In such a case, the first
In the control device of the embodiment, a right-and-left driving force difference is generated, so that proper driving force control is not performed, which is not preferable. On the other hand, in the present embodiment, only during turning traveling in which the left and right wheel loads are different. Since the load-corresponding control is performed on the vehicle, proper driving force control can be performed without causing the above-mentioned problems during straight traveling.

Third Embodiment A drive force control device for an electric vehicle according to a third embodiment of the present invention will be described with reference to FIG.

In the present embodiment, in the driving force control device for an electric vehicle of the first embodiment, a vehicle speed signal obtained from the vehicle speed sensor 11 is further input to the motor control amount calculation means 30, and the vehicle speed signal is also taken into consideration to obtain an appropriate value. The motor control amount is obtained.

Hereinafter, the difference from the first embodiment will be described in detail.

The control amount calculating means 30 of the present embodiment includes adders 311, 312, subtractors 321, 322, a multiplier 331, a divider 341, and a viscera 35.
1, 352, 353, a saturation amplifier 354, and a multiplier 332.
And a subtractor 325.

The saturation amplifier 354 is connected to the vehicle speed sensor 11 and outputs v / vc when v ≦ vc and 1 when v> vc based on the vehicle speed signal v output from the vehicle speed sensor 11. here,
vc is the limit vehicle speed, which is set to an appropriate value between 40km / h and 100km / h.

Next, the multiplier 332 is connected to the saturation amplifier 354 and the divider 341, multiplies the signal output from the saturation amplifier 354 by the signal (ΔW / W) output from the divider 341, and subtracts the signal. Output to the device 325.

Next, the subtractor 325 is connected to the multiplier 332 and the divider 341, subtracts the signal output from the divider 341 from the signal output from the multiplier 332, and outputs the signal to the multiplier 331. . Therefore, the output of the subtractor 325 is Becomes

As a result, the calculation result shown in Expression (17) is input to the multiplier 331 instead of ΔW / W. Therefore, the degree of dependence of ft _L ^* and ft _R ^{* on} the load movement ΔW / W is weakened as v increases. When v exceeds a constant value vc, the amount of load movement is ignored and the same driving force is commanded to the left and right wheels.

By doing so, the driving force control device for the electric vehicle according to the present embodiment has the effects of the driving force control device for the electric vehicle according to the first embodiment, and further has the following effects.

That is, in the first embodiment, when the vehicle is turning, a moment in a direction that promotes the turning is generated due to the difference in driving force between the inner and outer wheels. Although this effect is effective when traveling at low speeds, there is a problem that at high speeds, stability may be impaired in the case of a vehicle having sharp steering characteristics. On the other hand, in the present embodiment, the driving force difference between the inner and outer wheels is reduced as the speed increases, so that it is stable even at high speeds and does not cause the above problems during high speeds. Various driving force control becomes possible.

Fourth Embodiment A drive force control device for an electric vehicle according to a fourth embodiment of the present invention will be described with reference to FIG.

In this embodiment, in the drive force control device for an electric vehicle of the first embodiment, input signal changeover switches 81 and 82 and subtractors 83 and 84 are provided between the motor control amount calculation means 30 and the drive means 40.
Further, the slip detection means is provided with dividers 233, 234 and comparators 243, 244, and an amplifier for amplifying the signal output from the brake angle sensor 16 to the motor control amount calculation means 30.
355 is further provided.

Hereinafter, the difference from the first embodiment will be described in detail.

First, the brake angle sensor 16 is a potentiometer mounted so as to interlock with a brake pedal, measures a brake angle, and outputs a brake angle signal θb.

Next, the slip detecting means 20 includes amplifiers 211 and 212, subtractors 221, 222, dividers 231, 232 and comparators 241, 242.
In addition to the dividers 233 and 234 and the comparators 243 and 244,
It further comprises:

The divider 233 is connected to the vehicle speed sensor 11 and the subtractor 221, divides the signal output from the subtractor 221 by the vehicle speed signal v output from the vehicle speed sensor 11, and outputs a signal λl _L to the comparator 243. To do.

The divider 234 is connected to the vehicle speed sensor 11 and the subtractor 222, divides the signal output from the subtractor 222 by the vehicle speed signal v output from the vehicle speed sensor 11, and outputs a signal λl _R to the comparator 244. To do.

The dividers 233 and 234 calculate the lock (restraint) ratio of the left and right wheels as follows.

Comparators 243 and 244 are connected to dividers 233 and 234 and subtractors 83 and 84, respectively, and input signals λl _L ,
When λl _R exceeds -λ (λ = 0.2 to 0.3), 0 is output, and when λl _R does not exceed λl _L and λl _R , an arbitrary positive number smaller than the maximum control force of each wheel is output as the auxiliary braking force.

Next, the control amount calculation means 30 includes the adders 311 and 312 and the subtractor.
In addition to 321, 322, 323, 324, a multiplier 331, a divider 341, and amplifiers 351, 352, 353, it further comprises an amplifier 355 for amplifying the signal output from the brake angle sensor 16.

The amplifier 355 inputs the brake angle signal θb output from the brake angle sensor 16 and amplifies it by Kb times to obtain fb ^* = Kb · θ.
The signal of b is output.

Next, between the motor control amount calculation means 30 and the drive means 40,
Input signal changeover switches 81 and 82 and subtractors 83 and 84 are provided.

The subtractors 83 and 84 are connected to the b-side terminals of the amplifier 355 and the input signal changeover switches 81 and 82, respectively, and fb
Input the signal obtained by subtracting the corrected braking force from ^* to the terminal.

The input signal changeover switches 81 and 82 have subtractors 323 and 324 at their t-side terminals, subtracters 83 and 84 at their b-side terminals,
Furthermore, connect with the brake angle sensor 16 and the control terminal respectively,
When the brake angle signal θb = 0, the input terminal of the switch is switched to the t side, and when θb> 0, it is switched to the b side, which are output to the subtractors 411 and 421, respectively.

Accordingly, when θb = 0, that is, when the brake is not depressed, the input of the input signal changeover switches 81 and 82 is t.
Since it is connected to the terminal, it is executed in the same manner as in the first embodiment. When θb> 0, that is, when the brake is depressed, the inputs of the input signal changeover switches 81 and 82 are connected to the b-side terminal. Also, slip detection means
When the corrected braking force, which is the output of 20, is zero, the signal of Kb · θb obtained by multiplying the brake angle θb by Kb by the amplifier 355 is applied to the motor braking torque via the subtracters 83 and 84 and the input signal changeover switches 81 and 82. The commands f _L ^* and f _R ^* are output to the driving means 40.

Further, when the lock ratios λl _L and λl _R calculated from the vehicle speed and the rotational speeds of the left and right wheels by equation (18) do not exceed -λ (λ
l _L , λ l _R ≦ −λ), it is determined that the brake wheels are locked.
At this time, the comparators 243 and 244 display the corrected braking force command value fl.
Output _L and fl _R. Then, in the subtractors 83 and 84, fl _L and fl _R are subtracted from the original braking force command value Kb · θb, so that the motor braking force command is weakened more than when the lock is not generated. Therefore, the braking force of the braking wheel is weakened, so that the locked state is released and the wheel restores the adhesive force to the road surface. As a result, the braking force command value also returns to Kb · θb.

Hereinafter, the above process is repeated.

By doing so, the driving force control device for the electric vehicle according to the present embodiment has the effects of the driving force control device for the electric vehicle according to the first embodiment, and further has the following effects.

That is, during driving, the same effect as that of the first embodiment is obtained. In addition, it also has the function of operating the drive motor as a generator during braking and using it as a regenerative brake. The braking force of the motor is controlled so as to maintain a value near the maximum value within the range where the wheels do not lock, so it is possible to reliably stop without losing the directionality of the vehicle even on a frozen road surface with low friction. .

In the above-described embodiment, the drive source of the vehicle is a pair of left and right motors, but the present invention is not limited to this. For example, one or more motors may be provided in addition, and a hybrid power system equipped with an internal combustion engine is also provided. It may be a vehicle.

Further, the turning may not be performed only by a normal steering device, and a pair of left and right motors for steering may be provided separately from the drive motors of the above-described embodiments.

Further, the driving force control device for an electric vehicle according to the above-described embodiment,
It is especially suitable for recreational electric vehicles that run on various roads such as highways, mountain roads, and frozen roads.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing the concept of the present invention, FIG. 2 is a schematic configuration diagram of a prior art, FIGS. 3 and 4 show another invention, and FIG. 3 is a schematic configuration diagram showing the concept. FIG. 4 is a diagram showing this principle, FIG. 5 is a system configuration diagram showing the entire first embodiment, FIG. 6 is a partial system configuration diagram showing the second embodiment, and FIG. 7 is a third embodiment. Partial system configuration diagram showing an example,
FIG. 8 is a system configuration diagram showing the whole of the fourth embodiment. 11 …… vehicle speed sensor, 12 …… rotation speed sensor, 13 …… load sensor, 14 …… accelerator angle sensor, 20 …… slip detection means, 30 …… motor control amount calculation means, 40 …… driving means,
41 ...... first motor control means, 42 ... second motor control means, 43 ... electric power supply source, 51 ... first motor, 52 ... second motor, 61,62 ... driving wheels.

Front Page Continuation (72) Hidehiko Tanaka, Hidekazu Tanaka, Aichi-gun, Aichi-gun, Nagakute-cho, Aichi 41 1 of Yokochi Central Research Institute Co., Ltd. Address 1 Toyota Central Research Institute Ltd. Examiner Yasuhide Nishimura (56) References JP-A-60-169912 (JP, A)

Claims (1)

[Claims] 1. A driving force control device for an electric vehicle, wherein left and right driving wheels of a vehicle are driven by separate motors. A vehicle speed sensor for detecting a vehicle speed, and a rotational speed sensor for detecting a rotational speed of a driving wheel of the vehicle. A load sensor for detecting a load applied to a drive wheel of a vehicle, an accelerator angle sensor for detecting an accelerator opening, and a vehicle speed output from the vehicle speed sensor. A slip detection unit that calculates a slip ratio (idling ratio) of the driving wheels from the signal and the rotation speed signal output from the rotation speed sensor and outputs a driving force correction signal, and a driving force output from the slip detection unit. Based on the correction signal, the load signal output from the load sensor, and the accelerator angle signal output from the accelerator angle sensor, the driving force of the vehicle is corrected and controlled. Motor control amount calculation means for calculating a control amount commensurate with the driving force and / or the braking force required for the above according to the driving wheel load of the vehicle and outputting a control amount signal for each driving wheel, and the motor control amount calculation A first motor control device and a second motor control device for adjusting the electric power supplied to the motor based on the motor command signal as the control amount signal which is the output of the means; and the first motor control device and the second motor control device. A driving means comprising a power supply source connected to supply electric power to the motor; and a first motor for continuously and variably controlling the torque of the shaft of the left driving wheel based on the electric power controlled by the driving means, A driving force control device for an electric vehicle, comprising: a second motor that continuously and variably controls the torque of the shaft of the right driving wheel based on the electric power controlled by the driving means.