JPS61258607A - Controller of induction motor for vehicle - Google Patents

Abstract

PURPOSE:To smoothly travel even at an extremely low speed time by correcting an AC command signal in response to the output signal of pulsation-detecting means. CONSTITUTION:Coefficient generators 45, 47 output coefficients gamma and lambda in response to the rotating speed of an induction motor 5. A function generator 33 outputs a correction coefficient mu in response to the vibration in a battery voltage. A multiplier 51 multiplies a correction signal produced by multiplying the coefficient mu by the coefficient gamma by a coefficient A' in response to a torque signal A from an accelerator 13, and outputs a voltage command signal V. A multiplier 53 multiplies a coefficient A'' in response to a torque signal A by the coefficient lambda, and outputs a frequency command signal ws. A 3-phase sinusoidal wave generator 21 outputs a 3-phase sinusoidal wave signal in response to the signal V, a frequency command signal ws and the speed signal. Comparators 25, 27, 29 compare the 3-phase sinusoidal wave signals with a triangular wave signal, and supplies a pulse-width-modulated 3-phase signals to an inverter 3.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a control device for a vehicle induction motor that corrects pulsations in the rotational operation of an induction motor that drives an electric vehicle.

[Technical background of the invention and its problems]

Electric vehicles are expected to become popular because they have a variety of energy sources and the potential to improve the traffic environment. Conventionally, DC motors, which are easy to control, have been used as electric motors to drive electric vehicles, but AC induction motors have many features such as simpler structure, maintenance-free, compact size, light weight, and high efficiency compared to DC motors. Electric vehicles using electric motors are being developed.

This induction motor is driven by AC voltage that is converted from DC voltage from the vehicle battery using an inverter circuit.
In order to perform variable speed control of the induction motor with good response characteristics and high efficiency, variable voltage variable frequency control is used to variably control the frequency and voltage of the AC voltage supplied to the induction motor. Such a variable voltage frequency control system is described, for example, in Japanese Patent Laid-Open No. 55-63593.

In electric vehicles that adopt this type of control method,
The voltage command signal V and frequency command signal ωS supplied to the induction motor are calculated based on the torque command signal from the accelerator, that is, the acceleration/deceleration signal and the rotation signal from the induction motor, and the voltage command signal V and frequency command signal ωS supplied to the electric motor are calculated based on these signals. A phase sine wave current command signal is obtained, this three phase sine wave current command signal is pulse width modulated by amplitude control of the triangular carrier wave, and this sine wave pulse width modulation signal is used to control an inverter circuit consisting of transistors, etc. It converts DC voltage into three-phase AC voltage to drive an induction motor.

By the way, in the conventional control device configured in this way, the inverter circuit is controlled by a sine wave pulse width modulation signal, and the DC voltage from the battery is converted into three-phase AC voltage to drive the induction motor. However, due to the influence of harmonic components, pulsations occur in the rotation of the electric motor, especially when the vehicle is running at low speed, resulting in poor ride comfort.

[Object of invention, target]

The present invention has been made in view of the above, and an object thereof is to provide a control device for a vehicle induction motor that corrects pulsation in the rotation of the induction motor and operates smoothly.

[Summary of the invention]

In order to achieve the above object, an AC command signal is calculated according to the torque signal from the torque generation command means and the rotational speed signal of the induction motor, and the inverter circuit is controlled by the pulse width modulation signal of the AC command signal, thereby generating power from the battery. In a device for converting a DC voltage into an AC voltage and driving and controlling an induction motor using the AC voltage, the present invention provides a pulsation detection means for detecting pulsation in the rotational operation of the induction motor, and a detection signal of the pulsation detection means. and a correction means for correcting the AC command signal according to the AC command signal.

[Embodiments of the invention]

Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 1 is a circuit block diagram of a control device for a vehicle induction motor according to an embodiment of the present invention, and the control device for a vehicle induction motor is applied to an electric vehicle.

In the figure, DC voltage from an on-board battery 1 is supplied to a three-phase inverter bridge (hereinafter referred to as an inverter) 3, where it is converted into a three-phase AC voltage, and then supplied to an induction motor 5 that drives an electric vehicle. . The rotational speed of the induction electric motor ta5 is detected by the rotational speed detection sensor 7,
First and second coefficient generators 45.47 as angular velocity ω
and is supplied to the three-phase sine wave generator 21. The first and second coefficient generators 45, 47 generate coefficients γ and λ, respectively, depending on the rotation speed of the induction motor 5. The accelerator 13 supplies a torque signal, i.e. an acceleration/deceleration signal A, to a first and second function generator 41.43, which first and second function generators 41.43 receive the torque signal supplied from the accelerator 13. Coefficients A' and A-'' proportional to A are generated.

Further, a battery current detector 31 that detects the output current from the battery 1 is connected to the power line that supplies voltage from the battery 1 to the inverter 3.
The current value flowing from the battery 1 detected in step 1 is supplied to a function generator 33. The function generator 33 generates a correction coefficient μ for correcting the voltage command signal V applied to the induction motor 5 according to the fluctuations in the battery current. The average current 1 of the difference between and the current current l
When the ratio (1-T)/I to If there is no variation, a correction coefficient μ equal to “1” is output.

The coefficient γ from the first coefficient generator 45 is applied to a multiplier 49
In the multiplier 51, this correction signal is multiplied by a correction coefficient μ corresponding to the battery current from the function generator 33 and corrected.
The voltage command signal V corrected by this is multiplied by
is supplied to the three-phase sine wave generator 21. Further, the coefficient /M- from the second function generator 43 is multiplied by the coefficient λ from the second coefficient generator 47 in a multiplier 53, thereby transmitting the frequency command signal ωS to the three-phase sine wave generator 21. supplying. The three-phase sine wave generator 21 receives voltage command signals ■,
A three-phase sine wave signal having an amplitude and a phase current determined by the frequency command signal ωS and the angular velocity signal ω from the rotation speed detection sensor 7 is generated. This three-phase sinusoidal signal is supplied to one input of each comparator 25, 27, 29,
The amplitude is compared with the triangular wave signal from the triangular wave generator 23 supplied to each input of the other side, the three-phase sine wave signal is pulse width modulated, and this pulse width modulated three phase signal is sent to the inverter 3.
The DC voltage of the battery 1 is converted into a three-phase AC voltage, and the voltage is supplied to the induction motor 5 to drive the induction motor 5.

In the configuration as described above, the three-phase sine wave generator 21 generates coefficients A-, A output from the first and second function generators 41 and 43 in response to the torque signal A from the accelerator 13. A voltage command signal V and a frequency command signal ωS, which are calculated by multiplying " by coefficients γ and λ corresponding to each speed ω detected by the rotational speed detection sensor 7, respectively, are input, and based on these command signals and angular velocity ω, and outputs a three-phase sine wave signal.In this case, the voltage command signal V
The coefficient γ output from the first coefficient generator 45 in order to calculate 49 and corrected according to the battery current, so that an appropriate voltage command signal V is supplied to the three-phase sine wave generator 21.

More specifically, when an electric car is running at a constant speed, induction electric B! If there is no pulsation in the rotation of the motor 5, there is no fluctuation in the battery current, so the correction coefficient generator 33 outputs a correction coefficient μ=1, and the multiplier 49 in particular outputs the coefficient from the first coefficient generator 45. An appropriate voltage command signal V is supplied to the three-phase sine wave generator 21 without γ correction.

If there is pulsation in the induction motor 5 and the fluctuation in the battery N current is larger than the average value, the function generator 33 outputs a correction coefficient μ less than 1, and this correction coefficient causes the first coefficient to change. The coefficient γ from the generator 45 is corrected, so that the voltage command signal ■ corrected to correspond to the variation in battery current is supplied to the three-phase sine wave generator 21. Then, the three-phase sine wave generator 21 outputs a proper three-phase sine wave signal based on the input signal corrected according to the fluctuation of the battery current, and this signal is transmitted to the comparator 2.
5.27.29, the triangular wave signal from the triangular wave generator 23 is pulse width modulated by amplitude control, and is output to the inverter 3.
is supplied to The inverter 3 converts the DC voltage from the battery 1 into a three-phase AC signal using this pulse width modulation signal, and supplies the signal to the induction motor 5 to drive the induction motor 5 and correct pulsation. Conversely, when the variation in battery current is smaller than the average value, the function generator 33 outputs a correction coefficient μ〉1 larger than “1”, and this correction coefficient causes the correction coefficient from the first coefficient generator 45 to be The voltage command signal V, which has been corrected by the coefficient γ and which has been corrected to correspond to the variation in battery current, is supplied to the three-phase sine wave generator 21, thereby correcting pulsation. FIG. 2 is a waveform diagram showing changes in the voltage command signal V controlled with respect to such fluctuations in battery current. As a result, noticeable pulsations are suppressed, especially when the vehicle is running at low speeds, resulting in smooth running and improved ride comfort.

FIG. 3 is a circuit block diagram of a control device for a vehicle induction motor showing another embodiment of the present invention.

The embodiment shown in FIG. 1 has a battery current detector 31 and a function generator 33 in the embodiment shown in FIG. The only difference is that a function generator 17 and a multiplier 19 are provided to generate coefficients for correcting the voltage command signal V and frequency command signal ωS with respect to fluctuations in the rotational speed of the electric motor 5 to detect and correct pulsation. , and other configurations and operations are the same as those of the embodiment shown in FIG. 1, and the same components are given the same reference numerals.

The function generator 17 generates a fluctuation in the angular velocity ω representing the rotational speed from the rotational speed detection sensor 7, that is, a ratio (ω- ;)/d is calculated, and a correction coefficient μ for the fluctuation of the angular velocity is output. This correction coefficient μ is a value smaller than “1” (μ<1) when the variation in angular velocity is positive, and a value larger than “1” when the variation in angular velocity is negative.
μ〉1), and 1 if there is no fluctuation (μ=1)
It is. The correction coefficient μ output from the function generator 17 is supplied to multipliers 49 and 19. In the multiplier 49, the coefficient γ output from the first coefficient generator 45 is multiplied by the correction coefficient μ from the function generator 17 and corrected according to the rotational speed of the induction motor 5, thereby adjusting the appropriate voltage. A command signal V is supplied to a three-phase sine wave generator 21. Furthermore, in the multiplier 19, the multiplier 5
3, the frequency command signal ωS obtained by multiplying the coefficient A″ from the second function generator 43 by the coefficient λ from the second coefficient generator 47 is multiplied by the correction coefficient μ from the function generator 17. is corrected according to the rotational speed of the induction motor 5, thereby providing an appropriate frequency command signal ωS to the three-phase sine wave generator 21.
is being supplied to.

In the configuration as described above, when the vehicle is running at a constant speed and there is no pulsation in the induction motor 5, there is no rotational speed of the induction motor 5, so the function generator 17 outputs the correction coefficient μm1. The multiplier 49 supplies an appropriate voltage command signal V to the three-phase sine wave generator 21 that corrects the coefficient γ from the first coefficient generator 45, and the multiplier 19 supplies the appropriate voltage command signal V to the three-phase sine wave generator 21 that corrects the coefficient γ from the first coefficient generator 45. An appropriate frequency command signal ωS is supplied to the three-phase sine wave generator 21 without correcting the frequency command signal ωS.

If there is pulsation in the induction motor 5 and the fluctuation in rotational speed is positive, the function generator 17 sets a correction coefficient μ smaller than “1”.
1 is output, and the first coefficient generator 4
The voltage command signal V is supplied to the three-phase sine wave generator 21, and the voltage command signal V is supplied to the three-phase sine wave generator 21, and the voltage command signal V is supplied to the three-phase sine wave generator 21. The frequency command signal ωS from the oscilloscope is corrected to reduce the frequency command signal ωS, and the corrected frequency command signal ωS is supplied to the three-phase sine wave generator 21. And a three-phase sine wave generator 21
outputs a three-phase sine wave signal corresponding to the input signal that has been reduced and corrected in accordance with the rotational speed fluctuation in this way, and this signal is input to the comparators 25, 27, and 29 by changing the amplitude of the triangular wave signal from the triangular wave generator 23. The signal is pulse width modulated by control and supplied to the inverter 23. The inverter 3 uses this pulse width modulation signal to convert the DC voltage from the battery 1 into a three-phase AC signal and supplies it to the induction motor 5, and drives the induction motor 5 to reduce rotational torque to correct pulsation. There is.

Conversely, when the rotational speed fluctuation is negative, the function generator 17 outputs a correction coefficient μ>1 larger than "1", and this correction coefficient causes the coefficient γ from the first coefficient generator 45 to be The voltage command signal ■, which has been corrected for an increase corresponding to the variation in rotational speed, is sent to the three-phase sine wave generator 21.
is supplied to the multiplier 53 in the multiplier 19.
increases the frequency command signal ωS from , supplies the corrected frequency command signal ωS to the three-phase sine wave generator 21,
This drives the induction motor 5 to increase its rotational torque and corrects pulsation. As a result, - induction motor 5
When the rotational speed of the induction motor 5 increases during pulsation, that is, when the rotational torque increases, the torque is suppressed, and conversely, when the rotational speed decreases, that is, when the rotational torque decreases, the torque is increased. This control prevents pulsation, provides smooth running, and improves ride comfort.

〔Effect of the invention〕

As explained above, according to the present invention, the pulsation in the rotation of the induction motor is detected and the AC command signal is corrected according to the detected pulsation, so the pulsation of the induction motor is suppressed, and the motor Because it operates smoothly, when applied to an electric vehicle, it can run smoothly even at extremely low speeds, improving ride comfort.

[Brief explanation of the drawing]

Fig. 1 is a circuit block diagram of a control device for a vehicle induction motor showing an embodiment of the present invention, and Fig. 2 shows changes in the voltage command signal V controlled in response to fluctuations in battery current in the device shown in Fig. 1. FIG. 3 is a circuit block diagram of a control device for a vehicle induction motor showing another embodiment of the present invention. 1...Battery 3...Inverter 5...I! Conductive motor 7...Rotational speed detection sensor 13...Accelerator 17...Function generator 21...Three-phase sine wave generator 23...Triangular wave generator 25, 27, 29... Comparator 31 ... Battery current detector 33 ... Function generator 41.43, ... Function generator 45.47 ... Coefficient generator

Claims (2)

[Claims] (1) Calculate an AC command signal according to the torque signal from the torque generation command means and the rotation speed signal of the induction motor,
In a device for controlling an inverter circuit using a pulse width modulation signal of the AC command signal to convert a DC voltage from a battery into an AC voltage, and driving and controlling an induction motor using the AC voltage, in the rotational operation of the induction motor. A control device for an induction motor for a vehicle, comprising a pulsation detection means for detecting pulsation, and a correction means for correcting the AC command signal according to a detection signal of the pulsation detection means. (2) The control device for a vehicle induction motor according to claim 1, wherein the pulsation detection means includes a battery current detection means for detecting an output current of the battery.