JPS586095A - Operation controller for electric motor vehicle driven by induction motor using inverter - Google Patents

Abstract

PURPOSE:To enable to control an induction motor with rapid response by inertia running without stopping an inverter. CONSTITUTION:The output of a frequency/voltage converter 10 which converts the rotor frequency fr of an induction motor into a DC voltage is inputted to a speed deviation detector 13 and an adder 17. The output of a speed signal pattern circuit 11 which converts a speed command SP into a DC voltage is inputted to the detector 13. The output of the detector 13 is inputted through the first slip frequency function generator 14 to a low priority circuit 16. The output of a current limiting value pattern circuit 12 which converts a current limiting value command corresponding to the notch of an operation unit into a DC voltage according to the discrimination of the condition of a power drive operation and a regenerative operation is inputted through the second slip frequency function generator 15 to the circuit 16. The output of the circuit 16 is inputted to the adder 17, and the output of the adder 17 is inputted to a voltage/frequency converter 18 as a frequency output circuit which outputs an inverter frequency command.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an operation control device for an electric vehicle driven by an induction motor using an inverter.

Traditionally, electric cars have been driven by DC electric walls, but recently, induction/motor drive systems have been introduced, which have advantages in making the main circuit contactless, maintenance/maintenance/splitting, and improving adhesive performance. It is being adopted.

FIG. 1 shows the main circuit for starting an induction motor using a pulse width modulated inverter. As shown in the figure, DC power supply 1
The positive pole of is connected to the P terminal via the filter reactor 2, and the negative pole is directly connected to the N terminal. A filter capacitor 3 is connected in parallel with the DC power supply 1 and a pulse width modulation inverter 9 is connected between the P terminal and the N terminal. The inverter 9 has a parallel circuit of a series circuit of the main thyristor 4 and commutation reactor 7 and a series circuit of the auxiliary thyristor 5 and commutation reactor 7 connected in three rows and two columns, and also connects a commutation capacitor 6. It is configured. The output side of the inverter 9 is connected to the U-phase, ■-phase, and W-phase windings of the induction motor 8, respectively.

Next, the operation of the above-mentioned induction/motivation will be explained. induction motor 8
The modulated waves that determine the U-phase, ■-phase, and W-phase pulses of
The sine wave U(S, V(t) and W
(t), and the carrier wave is a frequency 3f shown in FIG. 2(a).
Assuming a triangular wave T (t), a U-phase modulated pulse is obtained, and when the difference is negative, a negative pulse is obtained. Therefore, when it is a positive pulse, the main thyristor 4 connected to the contact side is turned on, and when it is a negative pulse, the main thyristor 4 connected to the N contact side is turned on. In addition, the V phase modulation pulse is as shown in Figure 2 (C), and the voltage waveform between 1 in the U phase and V phase table is as shown in Figure 2 (d
). The pressure between the U phase and the V phase can be controlled by changing the pulse width t by varying the peak value of the modulated wave. changes,
Output pressure is controlled. In addition, although the case where the carrier wave of frequency 3f was used was demonstrated above, the same control can be performed also in the case of the carrier wave other than frequency 3f.

Therefore, the terminals of the induction motor are connected to y as shown in Figure 3.
A voltage ■ with a constant /f ratio is applied. However, [ is the inverter frequency. Further, if the current flowing through the induction motor is 1, and the frequency is the difference from the induction motor rotor frequency, that is, the slip frequency is 2 f , then there is a relationship shown in the following equation.

■ I-(-)t-f, ・・・・・・・・・
(1) Therefore, the current (2) flowing through the induction motor is controlled by controlling the slip frequency f.

By the way, 1. Operating conditions of electric vehicles that do not generate drive torque:
In normal, or coasting, mode of operation, electric vehicles using DC electric poles are operated by turning off the main circuit. On the other hand, when an electric car using an induction motor is coasted with the main circuit turned off, as in an induction motor using a DC motor, the residual voltage of the induction motor is If the voltage is turned on again before it disappears, the voltage phase shift and voltage difference will cause an overcurrent to flow into the inverter circuit and the induction motor safety circuit, resulting in torque/reduction and even commutation error in the inverter. There is a problem that this may lead to

For this reason, in the case of a large-capacity induction motor, the residual voltage extinction time constant reaches about 1 second, resulting in the problem that coordinated control cannot be performed. Another problem is that the switches wear out because the main circuit is turned on and off each time the vehicle coasts. In order to solve these problems, it is possible to reduce the voltage gradually just before the inverter stops to reduce the absolute value of the residual voltage, but as above, the coordination is poor, and the harmonic current increases. There is a problem that torque pulsation becomes large due to this. That is, the third
Comparing the case of operation at point A in the figure and the case of operation at point B, where the inverter output voltage is lower than point A, the fundamental wave voltage is lower at point B than at point A, and the harmonics As the voltage increases, the fundamental wave current decreases, the harmonic current increases, and the torque pulsation increases.

The present invention has been made to solve the above-mentioned problems, and is an electric vehicle driven by an induction motor using an inverter that does not stop the inverter and generate no drive torque during coasting operation. The purpose is to provide an operation control device.

The present invention includes a speed deviation detection circuit that detects a deviation between a speed command and an induction motor rotor frequency, and a first slip frequency function generator that outputs a first slip frequency signal based on the output of the speed deviation detection circuit. and a second coasting frequency function generator that outputs a zero slip frequency signal corresponding to the coasting position of the operating device and outputs a second slip frequency signal corresponding to the current limit value command of the operating device. a low priority circuit that compares the output of the first slip frequency function generator with the output of the second slip frequency function generator and passes the low level side output; and an inverter frequency based on the output of the low priority circuit. The above object is achieved by configuring the device to include a frequency output circuit that outputs a command.

An embodiment of the present invention will be described in detail below with reference to the drawings. As shown in FIG. 4, the rotor frequency f of the induction d-motor,
The output end of the frequency-voltage converter 10 that converts the DC voltage (Fr) into a DC voltage (Fr) is connected to a speed deviation detection circuit 13 and an addition circuit 17. In addition, the speed command S is set to the DC voltage Vsp
The output terminal of the speed signal pattern circuit 11 that converts the speed signal pattern into the speed signal pattern circuit 11 is connected to the speed deviation detection circuit 13. This speed deviation detection circuit 13 is connected to a low priority circuit 16 via a first slip frequency function generator 14 .

The current limit value pattern/circuit 12 that converts the current limit value command corresponding to the notch of the operating device into a DC voltage by determining the conditions of the forward operation and regenerative operation is a second constant frequency function generator 15.
It is connected to the low priority circuit 16 via. The output end of the low priority circuit 16 is connected to an adder circuit 17, and the adder circuit 17 is connected to a voltage-frequency converter 18 as a frequency output circuit that outputs an inverter frequency command.

As shown in FIG. 4, the first slip frequency function generator 14 includes a portion that outputs a slip DC voltage Vr −−0 corresponding to a slip frequency f in a predetermined range centered on the origin, and a portion centered on the origin. Speed deviation detection circuit 1 outside the specified range
3. It has a nonlinear characteristic consisting of a portion that outputs a slip DC voltage Vf- proportional to the output Δv6. Also, the second
As shown in FIG.
It has the characteristic of outputting t-f, and also has the characteristic of not outputting the slip DC voltage v,8 at the notch 0 point. Here 1. Since the driving torque T is expressed as shown in the following equation, if the slip frequency f is set to O for both power and regeneration, the driving torque T can be set to 0.

■ T-(-)”-f, ・・・・・・・・・
(2) In this embodiment, by operating the notch to 0, the slip DC voltage is 0, so the total frequency is 9.

By setting 0 to 0, the driving torque T is set to 0.

The operation of this embodiment will be explained below. The current limit value command corresponding to the notch of the operating device is converted into a DC voltage by the current limit value pattern circuit 12 by determining the conditions of power and regeneration. The slip frequency is given as a DC voltage Vfa. Further, the induction electric machine rotor frequency f2 is converted into a DC voltage Vtr by a frequency-voltage converter lO, the speed command S is converted into a DC' voltage Vsp by a speed signal converter/circuit 11, and the speed deviation The detection circuit 13 detects the difference voltage ΔV between the DC voltage Va and the DC voltage V tr. In response to this differential voltage ΔV, the first slip frequency function generator 14
The slip frequency is given as a DC voltage. Thus, when the output of the first all-9 frequency function generator 14 and the output of the second slip frequency function generator 15 are compared in the low priority circuit 16, a lower voltage is output from the low priority circuit 16,
An adder circuit 17 adds the output of the frequency-voltage converter 10 and the output of the low priority circuit 16, and the inverter frequency command f[NV is digitally given through the voltage-frequency converter 18. That is, the first slip frequency function generator 1
Based on the output of 6, when the notch of the operating device is set to 0 during acceleration, constant speed, and deceleration operation,
The second slip frequency function generator 15 generates a slip frequency O
The signal of 1. Coasting operation with zero drive torque is possible.

In addition, when entering coasting operation or from coasting operation to power (or regeneration) operation, by controlling the slip frequency according to a putter with a certain time constant, coasting operation and power (or regeneration) operation can be smoothly performed. The time constant of this pattern is determined by considering the secondary circuit 0 and f constant of the induction motor.

FIG. 6 shows the slip torque and current characteristics of the induction engine in this example. In the figure, the solid line represents the slip torque, and the dashed line represents the current characteristics.

In addition, in order to control the slip frequency to 0,
High frequency detection accuracy is required, but by adopting a digital control system that uses a complete microcomputer, control can be achieved with an accuracy of about 0.01%. Further, in the above, the case where a voltage-type auxiliary impulse commutation inverter using a reverse conduction thyristor is used has been explained, but the present invention should not be limited to this, and the same applies to an inverter using a GTO thyristor. Similar effects can be obtained even with a single-phase inverter.

As explained above, according to the present invention, coasting operation can be performed without stopping the inverter, which eliminates errors in inverter commutation, enables coordinated control, and reduces wear on switches. , an excellent effect can be obtained.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram of the main circuit that drives an induction motor by an inverter, Figures 2 (a) to (d) are diagrams showing waveforms of each part of the circuit in Figure 1, and Figure 3 is a circuit diagram of the main circuit that drives an induction motor using an inverter. A diagram showing the relationship between output frequency and inverter output voltage, FIG. 4 is a block diagram showing one embodiment of the present invention, and FIG. 5 is a diagram showing the relationship between output frequency and inverter output voltage.
FIG. 6 is a diagram showing the characteristics of the slip frequency function generator of FIG. l...DC power supply, 2...filter reactor, 3.
...Filter capacitor, 8...Induction motor, 9...
・Inverter, 13...Speed deviation detection circuit, 14...
- First slip frequency function generator, 15... Second slip frequency function generator, 16... Low priority circuit. °(,...power; 7 for 1 mouth too '2 mouth 13 mouth ♂ O isoheta book car shame - skin Maki (H [) also 4 (21 1'1 Asahi 5 mouth sushi C 巳

Claims (1)

[Claims] (2) A speed deviation detection circuit that detects the deviation between the speed command and the induction motor rotor frequency, and a first all-over frequency function generator that outputs a first slip frequency signal based on the output of the speed deviation detection circuit. and a second slip frequency function generator that outputs a zero slip frequency signal corresponding to the coasting operation position of the operating device and outputs a full second full frequency signal corresponding to the current limit value command of the operating device. , a low priority circuit that compares the first slip frequency function generator output and the second slip frequency function generator output and passes the low level side output; and an inverter frequency command based on the low priority circuit output. An operation control device for an electric vehicle driven by an induction motor using an inverter including a frequency output circuit that outputs a frequency output circuit.