JPH0568305A - AC electric vehicle controller - Google Patents

Abstract

(57) [Summary] [Purpose] To downsize GTO thyristors and equipment. A carrier frequency used for pulse width modulation of a VVVF inverter is set to an integral multiple of the inverter output frequency, and the ratio between the carrier frequency and the inverter output frequency is switched by a pulse mode switching unit based on the inverter frequency condition. At this time, by setting the pulse mode switching frequency for switching the ratio of the carrier frequency and the inverter output frequency to a frequency other than a frequency that is an even multiple of the input AC power supply frequency, a pulsating frequency that is twice the input AC power supply frequency can be obtained. By preventing the pulse mode switching control from being performed during the beat phenomenon that occurs when the inverter frequency approaches, it is possible to prevent frequent overcurrent of the motor current, improve controllability, and reduce the size of the device. Try.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an AC electric vehicle controller.

[0002]

2. Description of the Related Art A converter for converting an AC power supply into DC power and an AC electric vehicle control device for converting the output of the converter into AC power to drive and control an induction motor are conventionally shown in FIG. The composition is known.

In this conventional AC electric vehicle control device, the AC power received from the pantograph 101 is stepped down via a transformer 102 and input to a converter 103 composed of a power semiconductor element such as a thyristor and converted into DC. Then, it is smoothed by the capacitor 104 connected in parallel to the output side of the converter 103, and this direct current is supplied to the variable voltage variable frequency (VVVF) inverter 105 to be reconverted into desired AC power, which is used as a load. To the induction motor 106 to control the drive of the electric vehicle.

In FIG. 2, 107 is a speed detector for detecting the speed of the electric vehicle, and 108 is an inverter 10.
5, a DC voltage detector for detecting a DC voltage as an input of 5, reference numeral 109 is a converter control device for performing conversion control of the converter 103, and 110 is an inverter 105.
It is an inverter control device for controlling the.

In such a conventional AC electric vehicle controller, generally, the VVVF inverter 105 is controlled to keep the torque of the induction motor 106 constant at a constant slip frequency fs from a low speed region to a medium speed region. In addition, f / V constant control is performed to keep the ratio between the inverter output frequency f and the induction motor voltage VIM constant.

In the case of this constant f / V control, the GTO thyristor of the VVVF inverter 105 has its maximum breaking capability,
Due to limitations such as maximum switching frequency and gate turn-off time, the lower the inverter frequency fINV, the larger the ratio between the carrier frequency used for pulse width modulation and the inverter frequency, and the higher the inverter frequency fINV, the smaller the pulse mode switching control. Done.

[0007]

However, such a conventional AC electric vehicle controller has the following problems. FIG. 3 shows an example of the relationship between the modulation rate AL and the inverter frequency fINV during power running. In this FIG. 3, the straight line descending to the right shows the maximum modulation rate limit NPLIM for each pulse mode. At the point where the modulation rate AL of each pulse mode matches the maximum modulation rate limit, the pulse mode is shifted to a lower level. This is a control method that considers that the same performance can be obtained in the low speed range even if the power supply voltage fluctuates, and it is widely adopted in electric cars that use DC overhead power lines as a power source, but when the DC voltage changes Further, the relationship between the modulation factor AL and the inverter frequency fINV changes, and as a result, the pulse mode switching frequency also changes.

Further, the DC output voltage of the converter 103 contains a pulsating component having a frequency double that of the input AC power supply. When the inverter frequency approaches the pulsation frequency, a beat phenomenon occurs in the motor current due to the interference between the pulsation frequency and the inverter frequency. During the occurrence of this beat phenomenon, the state in which the peak value of the motor current continues to increase,
When a disturbance or the like is applied in that state, the threshold for overcurrent protection is more likely to be reached than when the beat phenomenon is not occurring.

Therefore, when the pulse mode is switched while the beat phenomenon is occurring, the ripple of the motor current due to the beat phenomenon is overlapped with the jumping out of the motor current due to the pulse mode switching, and the peak value of the motor current is increased to detect overcurrent protection. However, there is a problem in that the probability of is unnecessarily increased, and the VVVF inverter device is inevitably increased in size due to the increase in capacity of the GTO thyristor due to the maximum breaking current.

The present invention has been made in view of the above-mentioned conventional problems, and the pulse mode switching during the beat phenomenon is performed in order to avoid superimposition of the motor current ripple due to the beat phenomenon and the motor current due to the pulse mode switching. This can be prevented, frequent occurrence of overcurrent of the motor can be prevented, controllability can be improved, and VVV can be improved.
It is an object of the present invention to provide an AC electric vehicle control device capable of suppressing the maximum breaking current of the GTO thyristor used in the F inverter to a small size and downsizing the GTO thyristor and the device.

[0011]

SUMMARY OF THE INVENTION An AC electric vehicle controller of the present invention is a converter for converting AC power supplied from an AC power supply through a pantograph and a transformer into DC power of a constant voltage, and an output of this converter. And a voltage circuit pulse width modulation (P) for converting the DC power, which is input through the DC circuit and converted by the converter, into AC power.
WM) type variable voltage variable frequency (VVVF) inverter, an induction motor driven by AC power converted by the VVVF inverter, and a carrier frequency used for pulse width modulation of the VVVF inverter is an integral multiple of the inverter output frequency. A pulse mode switching unit for switching the ratio between the carrier frequency and the inverter output frequency based on the inverter frequency condition, wherein the pulse mode switching unit switches the ratio between the carrier frequency and the inverter output frequency. The frequency is set to a frequency other than an even multiple of the input AC power supply frequency.

[0012]

In the AC electric vehicle controller of the present invention, the AC power supplied from the AC power supply through the pantograph and the transformer is converted into the DC power of the constant voltage by the converter,
A converter output is smoothed by a capacitor connected to the output side of the converter and supplied to a voltage type pulse width modulation type VVVF inverter, and DC power is converted to AC power to obtain drive power for an induction motor.

The carrier frequency used for the pulse width modulation of the VVVF inverter is set to an integral multiple of the inverter output frequency, and the ratio of the carrier frequency to the inverter output frequency is switched by the pulse mode switching unit based on the inverter frequency condition. However, at this time,
By setting the pulse mode switching frequency for switching the ratio between the carrier frequency and the inverter output frequency to a frequency other than an even multiple of the input AC power supply frequency, the inverter frequency becomes the pulsating frequency of twice the input AC power supply frequency. By preventing the pulse mode switching control from being performed during the beat phenomenon that occurs at an approaching point, frequent overcurrent of the motor current is prevented to improve controllability, and the GT used in the VVVF inverter is also improved.
The O-thyristor can also keep the maximum breaking current small.

[0014]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 shows the circuit configuration of an embodiment of the present invention. The AC electric vehicle controller of this embodiment shows the configuration of a control circuit applied to the inverter controller 110 in the circuit of the general AC electric vehicle controller shown in FIG. A speed detector 2 for detecting a speed, a motor rotation speed calculation unit 3 for obtaining a motor rotation frequency fr from the speed signal of the speed detector 2, a slip frequency pattern calculation unit 4 for outputting a pattern of a slip frequency fs of an electric vehicle, and a motor By adding the motor rotation frequency fr by the rotation speed calculation unit 3 and the slip frequency fs by the slip frequency pattern calculation unit 4, the inverter frequency f
An adder 5 that outputs INV and a pulse mode switching circuit 6 are provided.

The pulse mode switching circuit 6 includes a pulse mode selection circuit 7. The pulse mode selection circuit 7 receives the inverter frequency fINV and outputs the preset pulse mode switching frequencies C1, C2, C.
Pulse mode selection signal 1P by comparison with 3 and C4
A circuit for outputting M, 3PM, 5PM, 9PM, 15M, and pulse mode switching frequency setting values C1, C
2, C3, C4 pulse mode switching frequency setting units 8-11, and the inverter frequency fINV for these pulse mode switching frequency setting values C1, C2.
Compared with C3 and C4, each pulse mode selection signal 1PM,
Comparator 12 that outputs 3PM, 5PM, 9PM, 15M
˜16, a pulse mode output unit 17 for outputting the pulse mode #NP (# indicates one of 1, 3, 5, 9, and 15) selected and determined by these comparators 12 to 16. ..

A PWM modulator 18 and a modulation rate calculator 19 are provided on the output side of the pulse mode switching circuit 6, and a pulse mode command that matches the current inverter frequency fINV as the output of the pulse mode selection circuit 7 is provided. It receives the value #NP.

Next, the operation of the AC electric vehicle control device having the above configuration will be described.

The speed signal detected by the speed detector 2 attached to the induction motor 1 is input to the electric motor speed calculator 3 in the inverter control device 110, and the electric motor rotation frequency fr is obtained. This motor rotation frequency fr
Is added to the slip frequency fs calculated by the slip frequency pattern generator 4 in the adder 5 and input to the pulse mode switching circuit 6 as the inverter frequency fINV. In addition, FIG. 1 shows a power running state,
The inverter frequency fINV is the sum of the motor rotation speed fr and the slip frequency fs.

In the pulse mode selection circuit 7 of the pulse mode switching circuit 6, the input inverter frequency fINV
In advance, the pulse mode switching frequency setter 8 ~
The pulse mode switching frequency set values C1, C2, C3 and C4 set in 11 and the comparator 12
16 to 16 and when the conditions are met, the respective pulse mode selection signals 15PM, 9PM, 5P
Outputs M, 3 PM or 1 PM.

Here, when the set values C1 to C4 of the pulse mode switching frequency setters 8 to 11 are frequencies of even multiples such as 2 times and 4 times the converter input AC power supply where the beat phenomenon occurs, for example, in the case of 50 Hz power supply. If the frequency is set to a value near 100 Hz, the ripple of the motor current due to the beat phenomenon and the jumping out of the motor current due to the pulse mode switching are overlapped as described in the explanation of the conventional example, and the peak value of the motor current is overlapped. Will lead to an excessive amount of.
Therefore, each of the set values C1 to C4 is set so as not to be an even multiple of the power supply frequency of the AC motor, such as 100 Hz, or a value in the vicinity thereof. However, in this case, the value needs to be set to a value equal to or less than the maximum modulation rate limit of each pulse mode caused by the limitation of the gate turn-off time of the GTO thyristor of the inverter 105.

Therefore, for example, 105 Hz, 90 Hz, 75Z, 60 Hz, etc. are set as the AL shown in FIG.

The pulse mode switching frequency #NP selected and determined by comparison with the pulse mode switching frequency set values C1 to C4 set as described above is the PWM
It is input to the modulation unit 18 and the modulation rate calculation unit 19, and constant motor torque control is performed from the low speed region to the medium speed region.

In this way, the pulse mode switching frequency 3NPT is output during the occurrence of the beat phenomenon that occurs when the pulsation frequency that is an even multiple of the frequency of the AC power source and the inverter frequency approach each other, which causes overcurrent detection. The possibility can be reduced.

[0025]

As described above, according to the present invention, the inverter frequency for switching the pulse mode is prevented from becoming a frequency in the vicinity of an even multiple of the AC power supply frequency by the pulse mode selection circuit. It is possible to avoid the electric current from jumping out and the ripple of the electric motor current during the beat phenomenon to be superposed, and to prevent the electric current from flowing into the electric current. In addition, the GTO thyristor used in the VVVF inverter can also suppress the maximum breaking current to a small value, and the GTO thyristor can be downsized.
The circuit can be miniaturized.

[Brief description of drawings]

FIG. 1 is a circuit block diagram of an embodiment of the present invention.

FIG. 2 is a functional block diagram of a general AC electric vehicle control device.

FIG. 3 is an operation explanatory diagram of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 induction motor 2 speed detector 3 electric motor rotation speed calculation unit 4 slip frequency calculation unit 5 adder 6 pulse mode switching unit 7 pulse mode selection circuit 8-11 pulse mode switching frequency setter 12-16 comparator 17 pulse mode output unit 18 PWM modulator 19 Modulation rate calculator

Claims (1)

[Claims] 1. A converter for converting AC power supplied from an AC power supply via a pantograph and a transformer into DC power of a constant voltage, and a DC circuit composed of a capacitor connected to the output side of the converter. A variable voltage variable frequency (VVVF) inverter of a voltage type pulse width modulation (PWM) system, which converts the DC power input through the DC circuit and converted by the converter into AC power, and the VVVF inverter An induction motor driven by AC power, and the VVV
A pulse mode switching unit for switching the carrier frequency used for the pulse width modulation of the F inverter to an integer multiple of the inverter output frequency and switching the ratio of the carrier frequency and the inverter output frequency based on the inverter frequency condition. The AC electric vehicle controller is characterized in that the pulse mode switching frequency for switching the ratio between the carrier frequency and the inverter output frequency is set to a frequency other than an even multiple of the input AC power supply frequency.