JPS59139802A - Controller for induction motor type electric rolling stock - Google Patents

Abstract

PURPOSE:To prevent the overspeed operation of an induction motor at the slipping time by providing a frequency limiter which limits the output frequency of an inverter to the frequency corresponding to the normal maximum operating speed of an electric rolling stock. CONSTITUTION:A current controller 5 compares a motor current IM with a command value IP and generates a slip frequency command fS. An inverter frequency command generator 7 adds a rotating frequency fR and the slip frequency command fS and generates an inverter frequency command f0. A low priority circuit 9 judges the low priority of the command f0 and the maximum frequency fMAX of the inverter corresponding to the preset normal maximum speed of an electric rolling stock. The output of the circuit 9 is applied as a frequency command to an inverter 2, and also applied as a voltage command to the inverter 2 through an f/V converter 8.

Description

[Detailed description of the invention] [Field of application of the invention] The present invention relates to a control device for an induction motor type electric vehicle.

[Prior art]

FIG. 1 is an electric circuit diagram showing a typical conventional example of a control device for an electric vehicle driven by an induction motor. In this figure, 1 is a pantograph, 2 is a variable voltage variable frequency inverter, 3 is an induction motor that drives an electric car, 4 is a current detector, and 5 is an induction motor that compares the motor current IM and its command value 2. A current control device that generates a slip frequency command f8 of the electric motor 3, 6 a frequency detector that detects the rotation frequency fR of the induction motor 3, and 7 an inverter frequency command f that is obtained by adding the rotation frequency fR and the slip frequency command f8. . an inverter frequency command generator that gives to the inverter 2;
is the inverter frequency command f. Output voltage command V corresponding to
. The output frequency and output voltage of the inverter 2 are the inverter frequency command f0 and the output voltage command V, respectively. controlled by

In such a conventional control device, the induction motor 30
The slip frequency command f8 is added to the rotational frequency fR, and this is set as the inverter frequency command f. Since the inverter frequency command f0 increases in accordance with the acceleration of the induction motor 3. Therefore, when the electric vehicle is operated at a speed close to the maximum normal operating speed, when the wheels spin, the rotational speed of the induction motor 30 becomes higher and higher, far exceeding the maximum normal rotational speed corresponding to the maximum normal operating speed. It rotates with high g and there is a risk of damaging the induction motor itself and the reduction gear. Therefore, in the past, the strength of the induction motor itself and the reduction gear were designed to withstand the maximum rotational speed that is the maximum normal rotational speed, which corresponds to the maximum normal operating speed of the electric vehicle, plus the speed increase due to idling. Therefore, there was a drawback that the induction motor, reduction gear, etc. became larger.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a control device for an induction motor type electric vehicle that eliminates the drawbacks of the prior art described above, prevents overspeed operation of the induction motor during idling, and makes it possible to reduce the size and weight of the induction motor. It is in.

[Summary of the invention]

In order to achieve this object, the present invention provides a frequency limiting means for limiting the output frequency of the inverter to a frequency corresponding to the maximum normal operating speed of the electric vehicle, and the maximum rotational speed of the induction motor is set to the maximum normal operating speed of the electric vehicle. The percentage mark is that the rotational speed is kept to the maximum normal rotation speed corresponding to .

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIG. Note that in FIG. 2, the same reference numerals as in FIG. 1 indicate the same or equivalent components.

This embodiment differs from the embodiment shown in FIG. 1 in the inverter frequency command f. A low priority circuit 9 as an inverter frequency limiting means is provided in the circuit that provides the inverter 2 and the V/f converter 8. This low priority circuit 9 receives the inverter frequency command f0 output from the inverter frequency command generator 7 and the maximum frequency f of the inverter corresponding to the preset maximum normal operating speed of the electric vehicle.
This is to judge the low priority with respect to MAX, and fo<fMAX
If so, the frequency command f. is transmitted as it is to the subsequent circuit, and the output frequency of the inverter becomes the frequency command f. is controlled by the value of Furthermore, even if the rotational frequency fR of the induction motor 30 increases due to wheel idling and becomes fo>fMAX, in this case, the highest frequency fMAX is transmitted to the subsequent circuit, so the output frequency of the inverter is equal to this highest frequency fMAX. can be suppressed to the value of

Therefore, even if the wheels spin, the maximum rotational speed of the induction motor 3 will not become abnormally high and can be suppressed to a rotational speed equivalent to the maximum normal operating speed of the electric vehicle. Also, damage to the reduction gear can be prevented. In addition, since the maximum rotational speed of the induction motor is suppressed to the maximum normal rotational speed that corresponds to the maximum normal operating speed of an electric vehicle, it is necessary to design the strength of the induction motor, etc., taking into account the increase in speed due to wheel slipping. Therefore, the maximum normal rotational speed of the induction motor can be designed to be as high as the strength of the induction motor allows, and the induction motor can be made smaller and lighter.

In addition to the low priority circuit, the inverter frequency limiting means may also be a means of detecting the absolute value of the induction motor 30 rotation frequency and cutting off the output of the inverter 2 when this reaches a set limit value. . However, this method of cutting off the output of the inverter 2 not only requires that the torque of the induction motor become zero when it idles at high speed, requiring the driver to restart the inverter by performing a reset operation, but also This is not a very desirable method, as the sudden change in speed will shock the passengers and significantly impair the comfort of the ride.

On the other hand, when a low priority circuit is used as in the above embodiment, the output of the inverter 2 is not cut off and operation continues, so there is no need to restart the inverter. Since at least the torque corresponding to the dynamic friction coefficient during idling is maintained, sudden changes in torque are less likely to occur, and riding comfort is less likely to be impaired. Of course, when the rail condition becomes good and the adhesion coefficient increases, the rail will naturally re-adhesion and operation will continue. In addition, when the readhesion device is separately provided, the readhesion device is activated, readhesion is performed, and the operation is continued.

FIG. 3 is an electrical circuit diagram of a control device according to another embodiment of the present invention. In FIG. 3, the same reference numerals as in FIGS. 1 and 2 indicate the same or equivalent components.

In this embodiment, the slip frequency command fs is given to the inverter frequency command generator 7 in an open loop, and the motor iI flow 1. The inverter output voltage control device f
This is applied to a method for controlling t1o. In the case of this embodiment as well, the output frequency of the inverter is suppressed to the value of the maximum frequency f by the low priority circuit 9.
The same effects as the embodiment shown in FIG. 2 described above can be obtained.

〔Effect of the invention〕

As explained above, according to the present invention, the maximum rotational speed of the induction motor can be suppressed to a rotational speed corresponding to the normal maximum operating speed of the electric vehicle by simply providing an inverter frequency limiting means. As a result, the induction motor is designed to prevent overspeed operation when the wheels are spinning, thereby preventing damage to the induction motor, auxiliary equipment, etc., and the maximum normal rotational speed of the induction motor to be as high as possible due to its strength. As a result, it becomes possible to reduce the size and weight of the induction motor 1.

[Brief explanation of the drawing]

FIG. 1 is an electric circuit diagram showing an example of a conventional control device for an induction motor type electric vehicle, and FIG. 8g2 and FIG. It is a circuit diagram. 2...Variable voltage variable frequency inverter, 3...
... Drive induction motor, 6... Frequency detector, 7... Inverter frequency command generator, 7.
...Low priority circuit (inverter frequency limiting means)

Claims (1)

[Claims] 1. A driving 'g'Ij4 electric motor, an inverter that drives the induction motor, a frequency detection means for detecting the rotational frequency of the induction motor, and a rotation detected by the frequency detection means. and a frequency control means for controlling the output frequency of the inverter according to an inverter frequency command created based on the frequency, wherein the output frequency of the inverter is set to the maximum normal operating speed of the electric vehicle. 1. A control device for an induction motor type electric vehicle, characterized in that a frequency limiting means for limiting to a corresponding frequency is provided. 2. The induction motor electric vehicle according to claim 1, wherein the frequency limiting means comprises a low priority circuit between the inverter frequency command and a frequency corresponding to the maximum normal operating speed of the electric vehicle. control device.