JPH0386004A - Speed controller for motor vehicle - Google Patents

Abstract

PURPOSE:To reduce electromagnetic noise of motor by performing drive control and brake control of the motor according to the pulse width modulated(PWM) output signal from a switching control section. CONSTITUTION:A drive control section 4 produces a PWM signal having such pulse width as corresponding to the magnitude of an output signal obtained by adding an acceleration signal to an output which is obtained by subtracting a rotation signal from the acceleration signal. A brake controls section 8 produces a PWM signal having pulse width corresponding to the magnitude of an output obtained by subtracting the acceleration signal from the rotation signal, and produces a brake signal when the subtracted output exceeds over a predetermined value. A switching control section 5 switches the PWM signal output from the drive control section 4 according to the forward/reverse control of a motor 11, and produces an output which is obtained by switching the PWM signal and the PWM signal from the brake control section according to the brake signal. A motor drive section 7 performs drive control or brake control of the motor 11 according to the PWM signal output from the switching control section 5. By such arrangement, electromagnetic noise of the motor 11 can be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a speed control device for an electric vehicle or the like, and particularly to a speed control device for an electric vehicle that reduces electromagnetic noise when a motor is driven.

[Conventional technology]

Conventionally, in the speed control device of an electric vehicle, a rotation speed pulse with a frequency proportional to the rotation speed of the motor is generated, this is converted to DC by a frequency/voltage (F/V) converter, and this output voltage and the output voltage of the accelerator are The number of revolutions of the motor is controlled by blocking current supply to the motor according to the comparison result.

FIG. 5 shows a conventional speed control device for an electric vehicle.

In FIG. 5, the accelerator unit 1 has an accelerator voltage vAcc consisting of a DC output according to the operation amount of the accelerator device.
occurs. This output voltage is added to the comparator 4++ in the drive control section 4 and compared with the triangular wave output of the reference triangular wave generator 2, thereby generating the accelerator voltage v
It is converted into a pulse width modulation (PWM) signal having a pulse width corresponding to the magnitude of acc. The motor drive unit 7 outputs a drive current whose magnitude changes according to the pulse width of this PWM signal to the motor 11, and the motor 11 rotates by this drive current to generate a drive force.

The rotational speed pulse generator 12 generates pulses with a frequency that changes depending on the rotational speed of the motor 11, and inputs the pulses to the F/V converter 3. The F/V converter 3 generates an output voltage whose magnitude changes depending on the frequency of the input pulse.

Further, in the drive control section 4, a comparator 4.2 compares the output of the F/V conversion section 3 and the accelerator voltage ■acc, and determines that the output of the F/V conversion section 3 is the accelerator voltage ■Acc.
When the level is higher, the output pulse of the comparator 4□ is cut off to prevent the motor 11 from being energized, thereby controlling the motor 11 to lose its driving force.

By performing such feedback control, the rotation speed of the motor 11 changes according to the operation of the accelerator section 1.
be controlled.

[Problems to be Solved by the Invention] In the conventional device as shown in FIG. is turned on and off,
Electromagnetic noise is generated from the motor.

In order to reduce such electromagnetic noise, it is conceivable to increase the frequency of the triangular wave of the reference triangular wave generator. However, the triangular wave frequency is at the audible limit of 20k (H
If the pulse frequency generated from the rotation speed pulse generator is low even if the rotation speed is increased to about z), the PWM from the drive control section
Since the wave output is modulated with the pulse frequency of the rotational speed pulse generator, electromagnetic sound at this frequency is still generated.

On the other hand, in order to bring the pulse frequency of the rotational speed pulse generator to the audible limit of about 20k (Hz), the structure of the rotational speed pulse generator becomes complicated and extremely high precision is required. This has the disadvantage that not only is there a cost disadvantage, but also that it is difficult to generate a two-phase output for detecting the rotation direction.

[Purpose of the invention]

The present invention aims to solve these problems of the prior art.

That is, in the present invention, in a drive device for an electric vehicle, PWM is always performed at the triangular wave frequency of the reference triangular wave generator in a certain load range regardless of the pulse frequency of the rotational speed pulse generator. The object of the present invention is to provide a speed control device for an electric vehicle that can reduce the generation of electromagnetic noise from a motor by increasing the triangular wave frequency.

[Means to solve the problem]

In the present invention, the motor is driven in accordance with an accelerator signal corresponding to the operation amount of the accelerator and a rotation speed signal corresponding to the rotation speed of the motor. Furthermore, a drive control section that generates a PWM signal with a pulse width corresponding to the magnitude of the output signal obtained by subtracting the rotational speed signal from the accelerator signal and the accelerator signal, and a drive control section that subtracts the accelerator signal from the rotational speed signal. A brake control section that generates a PWM signal with a pulse width corresponding to the magnitude of the output and generates a braking signal when this subtracted output exceeds a predetermined value, and forward/reverse control of the motor regarding the PWM signal output of the drive control section. A switching control section is provided that performs switching corresponding to the braking signal and switches and outputs the PWM signal and the PWM signal of the braking control section in accordance with the braking signal. Then, a motor drive unit is provided that performs drive control and braking control of the motor in accordance with the PWM signal output of the switching control unit! This is intended to achieve the above-mentioned purpose.

[Effect]

The accelerator section generates an accelerator signal VACC having a magnitude corresponding to the amount of operation of the accelerator. The reference triangular wave generator generates a triangular wave with a constant frequency. Further, the F/V converter generates a rotation speed signal VFV having a magnitude corresponding to the rotation speed of the motor.

The drive control section generates a PWM signal with a pulse width corresponding to the magnitude of an output signal obtained by adding the output obtained by subtracting the rotation speed signal from the accelerator signal and the accelerator signal. The braking control section generates a PWM signal with a pulse width corresponding to the magnitude of the output obtained by subtracting the accelerator signal from the rotation speed signal, and
When this subtracted output exceeds a predetermined value, a braking signal is generated.

The switching control section switches the PWM signal output of the drive control section corresponding to forward/reverse control of the motor, and switches and outputs this PWM signal and the PWM signal of the braking control section according to the braking signal. The motor drive section performs drive control and braking control of the motor in accordance with the PWM signal output from the switching control section.

Therefore, according to the present invention, PWM control is always performed at the reference oscillation frequency in a certain load range, so that electromagnetic noise based on pulses from the rotation speed detector can be reduced. Furthermore, since dynamic braking is also performed at the reference oscillation frequency, electromagnetic noise is similarly reduced.

C Embodiment] The present invention will be explained below based on FIGS. 1 to 4.

In the embodiment shown in FIG. 1, the motor 11 is driven in accordance with an accelerator signal corresponding to the operation amount of the accelerator 11 and a rotation speed signal corresponding to the rotation speed of the motor 11. Furthermore, a drive control unit 4 generates a PWM signal with a pulse width corresponding to the magnitude of the output signal obtained by subtracting the rotational speed signal from the accelerator signal and the accelerator signal, and a drive control unit 4 that subtracts the accelerator signal from the rotational speed signal. The brake control unit 8 generates a PWM signal with a pulse width corresponding to the magnitude of the output and generates a brake signal when the subtracted output exceeds a predetermined value, and the PWM signal output of the drive control unit 4 is controlled by the motor 11. A switching control section 5 that performs switching corresponding to forward/reverse control and also switches and outputs this PWM signal and the PWM signal of the control/zero control section 8 according to a braking signal, and a PWM signal output of this switching control section 5. A motor drive unit 7 is provided to perform drive control and braking control of the motor 11 accordingly.

To explain this in more detail, FIG. 1 shows the circuit configuration of one embodiment of the present invention, and corresponding parts in the conventional circuit shown in FIG. 5 are indicated by the same numbers.

In the accelerator unit 1, the accelerator voltage adjustment unit l adjusts the output voltage from the accelerator II based on the accelerator operation so that the motor 11 has a predetermined rotation speed under a predetermined load condition, and adjusts the accelerator voltage. Generate V Ace.

In the drive control unit 4, the accelerator voltage V Ace is applied to the comparator 4. The signal is input into the reference triangular wave generator 2 and compared with the reference triangular wave signal of the reference triangular wave generator 2, thereby converting it into a PWM signal having a pulse width corresponding to the magnitude of the accelerator voltage V Aee.

This PWM signal is input to the switching control section 5, and the game) 5 generates an output according to the switching signal of the forward/reverse switching section 6.
+,5z controlled by gates 5, . 5. The signal is input to the motor drive section 7 through one of the following. In the motor drive unit 7, the driver 7 converts the PWM signal into a drive current, and the transistors 7 and 7S, or 74 and 7. By turning on the motor 11, the motor 11 is rotated forward or reverse at a rotation speed according to the PWM signal.

On the other hand, a rotation speed pulse having a frequency corresponding to the motor rotation speed generated from the rotation speed pulse generator 2 placed coaxially with the motor 11 is converted into a frequency/voltage (F/V ) is converted into a pulsating output according to the pulse frequency by the conversion I03z, and the amplifier 3. The gain is adjusted to produce a rotational speed signal VFV.

In the drive control section 4, a differential amplifier 4. generates an output obtained by subtracting the rotational speed signal Vrv from the accelerator voltage V ACe, and this output is added to the accelerator voltage v a in the adder 4□.
It is added to ce.

That is, at a certain rotation speed of the motor 11, the differential amplifier 4. outputs a constant level voltage, and the accelerator signal V A
ce is added to motor 1 by a constant PWM signal.
1 is being rotated, but if the vehicle speed decreases due to an increase in load, the output voltage of the differential amplifier 4 increases, the adder output also increases, and the duty of the PWM signal increases. As a result, the drive current in the motor drive unit 7 is increased, and the motor 11 is controlled to recover its deceleration speed.

On the other hand, when the vehicle speed increases, the output voltage of the differential amplifier 4I decreases, thereby controlling the rotation speed of the motor 1 to decrease.

Furthermore, when the rotational speed signal VFV is larger than the accelerator signal VkCt by a certain degree, that is, when the speed is in a deceleration state, the differential amplifier 4. Even if the output reaches 10'', the speed will not decelerate immediately. The differential amplifier 8I generates an output obtained by subtracting the accelerator signal v ace from the rotational speed signal VFV, and the comparator 8□ generates a low level output when the output of the differential amplifier 8I becomes larger than a certain level, and switches. Diode 5 in the control section 5. ．． Gate 51-5 via 5@
□ is turned off to cut off the input from the drive control section 4, and the comparator 8. Differential amplifier 8. is compared with the reference triangular wave signal of the reference triangular wave generator 2 to generate a PWM signal having a pulse width proportional to the absolute value of the difference between the rotational speed signal VFV and the accelerator signal VAl:C.

This PWM signal is inputted to the motor drive unit 7 through the OR gates 5s, 5=, turns on the transistors 7□ to 7, and drives the motor 11 so as to short-circuit it. Therefore, the electric power generated by the motor 11 as a generator is consumed in a short circuit, and so-called dynamic braking is performed. Since this dynamic braking is also performed according to the pulse width of the PWM signal, braking with linearity is performed.

Note that in FIG. 1, the reference triangular wave generator 2 is the reference oscillator 2. The reference frequency pulse of is integrated by the integrating circuit 22,
Amplifier 2. It is configured to output as a triangular wave after passing through.

Further, the forward/reverse switching section 6 is rotated forward/backward by the switch 61.

In response to the reversal, a high-level signal and a low-level signal are switched and output, and this signal and a signal inverted via the inverter 6t are output as switching signals.

The stabilized power supply unit 9 generates a voltage VCC stabilized by the power supply IC 9° when the voltage of the battery 14 is supplied through the main switch 13. The voltage VCC is used as a source for each part except for driving the motor.

FIG. 2 shows another embodiment of the present invention,
Differential amplifier 40. The L output level is made variable. The loop gain of the control circuit during drive control can be easily adjusted using the variable resistor VRI. Also, the loop gain of the control circuit during braking control is determined by the variable resistor VR
2 can be easily adjusted.

3(a) to (C) show the PWM signal of the drive control section 4 and the PWM signal of the braking control section 8 in response to changes in load and changes in the amount of accelerator operation in the circuit of the present invention. It is something that

When the accelerator signal V ACC is applied as shown by the solid line in FIG.
As shown in the same figure (b), the PWM signal has a large duty during acceleration when the accelerator signal VACC exceeds the rotational speed signal VFV, and a small duty when decelerating when the rotational speed signal VFV exceeds the accelerator signal Vscc. controlled as follows.

Also, during deceleration, the rotational speed signal V□ and the accelerator signal V Ae
When the difference with C becomes larger than a certain level, and therefore the duty of the PWM signal of the drive control section 4 becomes "OJ",
As shown in FIG. 3(C), the PWM signal of the brake shelf section 8 is output.

FIG. 4 shows the differential amplifier 4. of the drive control section. (shown by the broken line) and the output of the differential amplifier 8 of the brake control section (shown by the - dotted chain line).The difference between the rotation speed signal and the accelerator signal (VFVVAcc) is It is shown that after OJ, different outputs are generated depending on whether the difference is positive or negative.

〔Effect of the invention〕

As explained above, according to the present invention, in a drive device for an electric vehicle, in a certain load range, the drive is always driven by the PWM signal of the triangular wave frequency of the reference triangular wave generator, regardless of the pulse frequency of the rotation speed pulse generator. Since the control is performed, the generation of magnetic noise from the motor can be reduced by increasing the triangular wave frequency to a higher frequency. Similarly, in dynamic braking, braking control is performed using a PWM signal with a reference triangular wave frequency, so less electromagnetic noise is generated, and the PWM signal gradually applies braking from a small level, so braking is performed smoothly. . Furthermore, since linear feedback control is performed in the present invention, it is easy to adjust the loop gain. In addition, level adjustment during dynamic braking is easy. Further, according to the present invention, there is no need to particularly increase the number of pulses per rotation of the rotation speed pulse generator, which is economical.

[Brief explanation of drawings]

Fig. 1 is a diagram showing one embodiment of the present invention, Fig. 2 is a diagram showing another embodiment of the present invention, and Figs. 3 (a) to (C) are variations in load and accelerator operation amount. FIG. 4 is a diagram showing the characteristics of the output of the differential amplifier of the drive control section and the output of the differential amplifier of the braking control section,
FIG. 5 is a diagram showing a conventional speed control device for an electric vehicle. h°° Accelerator, 4- Drive control section, 5- Switching control section, 7- Motor drive section, 8- Braking control section, 11-
-1-Motor. Figure 2 (Iseni/) YZL Kanami 4?1) Acc Figure 3 (Nagato Z braking output on which G is loaded) (a) (b) (c)

Claims (1)

[Claims] (1) In a speed control device for an electric vehicle that drives a motor according to an accelerator signal corresponding to the operation amount of an accelerator and a rotation speed signal corresponding to the rotation speed of the motor, the rotation speed signal is subtracted from the accelerator signal. a drive control unit that generates a PWM signal with a pulse width corresponding to the magnitude of the output signal obtained by adding the output of the rotation speed signal and the accelerator signal; and a PWM signal with a pulse width corresponding to the magnitude of the output obtained by subtracting the accelerator signal from the rotation speed signal. a brake control unit that generates a signal and generates a brake signal when the subtracted output exceeds a predetermined value; and a brake control unit that switches the PWM signal output of the drive control unit in accordance with forward/reverse control of the motor and outputs the brake signal. a switching control section that switches and outputs the PWM signal and the PWM signal of the braking control section according to the switching control section; and a motor driving section that performs drive control and braking control of the motor according to the PWM signal output of the switching control section. A speed control device for an electric vehicle, characterized in that it is provided with.