JPH05328531A - Controller for motor of motor-driven vehicle - Google Patents

Abstract

PURPOSE:To eliminate traveling failure even if accelerator pedal is excessively depressed in a state that capacity of a battery is reduced. CONSTITUTION:A voltage command signal S is generated according to outputs of a functional generator 41, a coefficient generator 45 based on a torque command signal A from an accelerator 13 and a rotating speed signal omega of a motor 5. An AC command signal is formed by a three-phase sine wave generator 21 from frequency command signals omegaS, V and omega similarly obtained, modulated by a triangular wave generator 23, comparators 25, 27, 29 to control an inverter 3. When a voltage detected by a battery voltage detector 31 is low, a correcting coefficient generator 50 outputs a correction coefficient alpha smaller than 1 to a multiplier 49, and a voltage command signal V is lowered. Thus, an output current of a battery is suppressed, to eliminate excessive drop of a battery voltage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor control device for an electric vehicle, and more particularly to a motor control device for an electric vehicle, the operation of which is corrected in response to variations in battery voltage.

[0002]

2. Description of the Related Art As a conventional controller for a motor for an electric vehicle, there is one disclosed in Japanese Patent Laid-Open No. 61-262006. As shown in FIG. 4, the induction motor 5 is used as a motor for driving the vehicle, and the accelerator 13 as an output commander is used.
The voltage command signal V and the frequency command signal ω S supplied to the induction motor are calculated based on the torque command signal A output from the induction motor 5 and the rotation speed signal ω from the induction motor 5. The three-phase sine wave current command signal supplied to the induction motor by these signals is obtained by the three-phase sine wave generator 21, and this current command signal is pulse-width-controlled by the amplitude control using the carrier triangular wave from the triangular wave generator 23. Is modulated. The modulated signal is used to control the three-phase inverter bridge circuit 3 to convert the DC voltage from the battery 1 into a three-phase AC voltage to drive the induction motor. In order to prevent the accelerator feeling from becoming significantly different even when the battery voltage drops, a correction coefficient generator 33 is provided to output a correction coefficient μ larger than "1" when the battery voltage drops. However, the voltage command signal V is kept high by performing a correction corresponding to the decrease in the battery voltage.

[0003]

According to the above structure, when the battery voltage drops, the output current from the battery 1 is increased in order to respond to the voltage command signal V which is maintained high. However, the decrease in the battery voltage is a state in which the remaining battery capacity is low, and if the output current is increased here, the battery voltage will further decrease due to the influence of the internal impedance of the battery 1. That is, when the driver depresses the accelerator 13 too much when the battery capacity is low,
The battery voltage becomes lower than the discharge end voltage of the battery and the operable voltage of the control device, circuit breaker, etc.,
As a result, there is a risk that the vehicle may be unable to travel even when the battery capacity still remains. Therefore, in view of the above-mentioned conventional problems, the present invention prevents the phenomenon that the vehicle cannot run even if the output commander is operated a lot when the battery capacity is low. It is an object of the present invention to provide a control device of the.

[0004]

Therefore, according to the present invention, an AC command signal is generated according to a torque signal from an output commander and a rotation speed signal of a motor, and an inverter circuit is generated by a pulse width modulation signal of the AC command signal. In a controller for an electric vehicle motor that drives the motor with the AC voltage by converting the DC voltage from the battery into an AC voltage, and battery voltage detection means for detecting the voltage value of the battery; In addition, when the battery voltage value becomes lower than a predetermined value, a correction means for decreasing the voltage value of the AC command signal is provided.

[0005]

Since the voltage value of the AC command signal is lowered when the battery voltage value is lower than the predetermined value, the output current from the battery is suppressed below the level corresponding to the operation of the output command device. As a result, even if the output commander is operated a lot, the battery voltage will not exceed the discharge end voltage or the like and drop too much.

[0006]

FIG. 1 shows an embodiment of the present invention. A DC voltage from a battery 1 mounted on a vehicle is supplied to a three-phase inverter bridge circuit (hereinafter abbreviated as an inverter) 3, converted into a three-phase AC voltage, and an induction motor 5 for driving the vehicle.
Is supplied to. The rotation speed of the induction motor 5 is detected by the rotation speed detection sensor 7 and supplied to the first and second coefficient generators 45 and 47 and the three-phase sine wave generator 21 as a rotation speed signal ω. First and second coefficient generator 4
Reference numerals 5 and 47 generate coefficients γ and λ in accordance with the rotation speed of the induction motor 5, respectively.

The accelerator 13 outputs the torque command signal A, that is, the acceleration / deceleration signal, to the first and second function generators 41 and 43.
To the first and second function generators 41, 43
Generates coefficients A ′, A ″ that are proportional to the torque command signal A supplied from the accelerator 13. Further, the battery 1 is provided between the power supply lines that supply the voltage from the battery 1 to the inverter 3.
A battery voltage detector 31 for detecting the voltage of
The voltage value of the battery 1 detected by the battery voltage detector 31 is supplied to the correction coefficient generator 60.

The correction coefficient generator 60 generates a correction coefficient α for correcting the voltage command signal V applied to the induction motor 5 in accordance with the battery voltage. This correction coefficient α is "when the battery voltage drops. It is set to be smaller than "1" and equal to "1" when the battery voltage is high.
The battery voltage detector 31 has a large time constant in order to prevent pulsation and slows the response.

The coefficient γ generated by the first coefficient generator 45
Is corrected by being multiplied by a correction coefficient α according to the battery voltage from the correction coefficient generator 60 in the multiplier 49, and further in the multiplier 51 by the corrected signal.
The coefficient A ′ from the function generator 41 is corrected to generate the voltage command signal V, which is supplied to the three-phase sine wave generator 21. Further, the coefficient A ″ generated by the second function generator 43 is corrected by the coefficient λ from the second coefficient generator 47 in the multiplier 53 to generate the frequency command signal ω S,
This is supplied to the three-phase sine wave generator 21.

The three-phase sine wave generator 21 has a voltage command signal V,
A three-phase sine wave AC signal having an amplitude and a phase determined by the frequency command signal ω S and the rotation speed signal ω from the rotation speed detection sensor 7 is generated. This three-phase sine wave signal is supplied to one input of each of the comparators 25, 27 and 29, and amplitude-compared with the triangular wave signal input from the triangular wave generator 23 to each of the other inputs, and pulse width modulated. The pulse width modulated three-phase signal is supplied to the inverter 3 to control it. As a result, the DC voltage of the battery 1 is converted into a three-phase AC voltage and supplied to the induction motor 5, and the induction motor 5 is controlled and driven.

As described above, the coefficient γ output from the first coefficient generator 45 to calculate the voltage command signal V is
The multiplier 49 multiplies the correction coefficient α output from the correction coefficient generator 60 according to the battery voltage detected by the battery voltage detector 31, and corrects according to the battery voltage. Here, when the voltage of the battery 1 is high immediately after charging, the correction coefficient generator 60 outputs the correction coefficient α = 1, and in the multiplier 49, the coefficient γ from the first coefficient generator 45 is its value. , The proper voltage command signal V based on the rotation speed of the induction motor 5 and the torque signal from the accelerator 13 is supplied to the three-phase sine wave generator 21.

As the battery consumption progresses, the voltage E of the battery 1
In the state where B becomes lower than the predetermined value Vs, the correction coefficient generator 60 sets “1” on the line connecting the point a at α = 1 at Vs and the point b at α = 0 at the control device operable voltage Vc, for example.
A smaller correction coefficient α is output, and the coefficient γ from the first coefficient generator 45 is corrected by this correction coefficient α. As a result, the voltage command signal V for the same accelerator operation becomes smaller than that when the battery voltage is high. The three-phase sine wave generator 21 outputs a three-phase sine wave AC signal based on the input signal thus corrected according to the battery voltage,
This signal is sent to the comparators 25, 27 and 29 to generate the triangular wave generator 23.
The pulse width is modulated according to the amplitude comparison with the triangular wave signal from and is supplied to the inverter 3.

As a result, when the voltage of the battery 1 is reduced, the amplitude value of the three-phase AC voltage signal supplied to the induction motor 5 is reduced, so that the discharge end voltage of the battery, the control device, and the cutoff. It is possible to prevent the voltage from dropping below the operable voltage of the device. Therefore, when the battery capacity is still small, the vehicle will not be disabled due to excessive depression of the accelerator 13.

FIG. 2 shows a second embodiment of the invention. An accelerator correction coefficient generator 70 is provided instead of the correction coefficient generator 60 in the previous embodiment. The voltage value of the battery 1 detected by the battery voltage detector 31 is supplied to the accelerator correction coefficient generator 70. Similar to the correction coefficient generator 60, the accelerator correction coefficient generator 70 becomes smaller than "1" when the battery voltage drops and equals "1" when the battery voltage is high, according to the battery voltage. The correction coefficient β is output. A multiplier 72 is provided on the torque signal A output line from the accelerator 13, and the output of the accelerator correction coefficient generator 70 is input to the multiplier 72. The coefficient γ generated by the first coefficient generator 45 is directly multiplied by the coefficient A ′ from the first function generator 41 in the multiplier 51, and then the voltage command signal V is supplied to the three-phase sine wave generator 21. Supplied. The other structure is the same as that of the previous embodiment.

As a result, the torque signal A from the accelerator 13 is multiplied by the correction coefficient β, and when the battery voltage is reduced, the accelerator depression amount is corrected to be smaller than it actually is. This also prevents the vehicle from becoming inoperable due to excessive depression of the accelerator when the battery voltage drops.

The point b in the correction coefficient generator 60 or the accelerator correction coefficient generator 70 is not limited to the control device operable voltage Vc, but may be the discharge end voltage of the battery, the operable voltage of the circuit breaker, or the like as necessary. An appropriate function can be set without being limited to the straight line that is determined and connects the points a and b.

For example, as shown in FIG. 3, a correction coefficient (α or β)> 1 between points c and d of a predetermined battery voltage value.
As the voltage command signal V increases in accordance with the voltage decrease, the sense of response to the depression of the accelerator does not change, and when the battery voltage further decreases, the correction coefficient is set between points d and e. 0
It can also be set so as to decrease toward.

[0018]

As described above, according to the present invention, when the battery voltage is reduced, the correction means for reducing the voltage command signal for driving the motor is provided as compared with when the battery voltage is high. Even if the driver depresses the accelerator a lot,
It does not fall below the operable voltage of the control device.
As a result, as long as the battery capacity remains, it is possible to operate the electric vehicle without worrying about the operation and without worrying about the vehicle being unable to run.

[Brief description of drawings]

FIG. 1 is a diagram showing a first embodiment of the present invention.

FIG. 2 is a diagram showing a second embodiment.

FIG. 3 is a diagram showing an example of a function of a correction coefficient.

FIG. 4 is a diagram showing a conventional example.

[Explanation of symbols]

 1 Battery 3 Three-Phase Inverter Bridge Circuit 5 Induction Motor 7 Rotational Speed Detection Sensor 13 Accelerator 21 Three-Phase Sine Wave Generator 23 Triangle Wave Generator 25, 27, 29 Comparator 31 Battery Voltage Detector 33 Correction Coefficient Generator 41 First Function generator 43 Second function generator 45 First coefficient generator 47 Second coefficient generator 49, 72 Multiplier 60 Correction coefficient generator 70 Accelerator correction coefficient generator V Voltage command signal ωS Frequency command signal ω Rotation Speed signal α, β correction factor

Claims (1)

[Claims] 1. An AC command signal is generated in accordance with a torque signal from an output command device and a motor rotation speed signal, and an inverter circuit is controlled by a pulse width modulation signal of the AC command signal to convert a DC voltage from a battery. In a control device for a motor for an electric vehicle that converts the voltage into an AC voltage and drives the motor by the AC voltage, a battery voltage detection unit that detects a voltage value of the battery, and the detected battery voltage value is lower than a predetermined value. The control device for an electric vehicle motor, comprising: a correction unit that lowers the voltage value of the AC command signal in this state.