JPH07118842B2 - Induction motor type electric vehicle controller - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a control device for an electric vehicle driven by an induction motor.

[Background of the Invention]

A control device for an induction motor type electric train is disclosed in, for example, a paper entitled "Higashi Osaka Ikoma Electric Railway 7000 Series Inverter Train" in Science of Electric Cars, Vol. 38, No. 2, pp. 15-24.

In such a conventional control device, vibration may occur in the mechanical system and the electrical system at the time of starting when a large torque is required as a drive torque for each induction motor.

[Object of the Invention] An object of the present invention is to provide a control device for an induction motor type electric vehicle capable of performing reliable start without vibration at the time of start when a large torque is required as a drive torque for each electric motor. Is.

[Outline of Invention]

When the operating conditions of the train of the vehicle change such that a larger torque than usual is required for each induction motor, mechanical vibration increases.

The mechanical system vibration of the vehicle acts synergistically with the electric control system of the control device for controlling the motor to increase the amplitude, and the vibration becomes larger and larger.

That is, the torque generated by the main motor is transmitted to the trailing vehicle through the drive device, the wheels, the bogie frame, the vehicle body, and the coupler. A clearance and a spring system exist in the path for transmitting the torque. Therefore, immediately after starting, the rotational speed of the main motor becomes unstable until the play and the spring system are completely compressed. As an example, consider a case where there is a large clearance between the electric vehicle and the trailer vehicle, and the torque generated by the main motor accelerates the electric vehicle. Until there is no gap in the coupler, the only load seen by the main motor is the electric vehicle. When there is no play, the torque is also transmitted to the trailing vehicle, and the load seen by the main motor is the electric vehicle and the trailing vehicle. There is no problem if the load changes gently, but if there is a lot of play, the electric vehicle will accelerate and then collide with a trailing vehicle, causing a sudden change in the load. For this reason, the rotation speed of the main motor temporarily changes suddenly, and thereafter, vibrations corresponding to the resonance frequency of the mechanical system occur.

Moreover, it has been confirmed that if this vibration is large, an overcurrent may occur, and the main circuit may be cut off by the protection device, resulting in failure of activation.

Therefore, in the present invention, a power converter that outputs a variable voltage and a variable frequency, an induction motor that is fed by this power converter, speed detection means that obtains a speed signal corresponding to the speed of the vehicle, and a slip frequency command are provided. Means for outputting, first voltage command means for outputting an output voltage command of the power converter based on a deviation between a current command of the induction motor and a motor current, an output of the speed detecting means and the slip frequency command. And a means for obtaining an output frequency command of the power converter by addition and subtraction of the electric power converter, a second output means for outputting an output voltage command of the power converter substantially proportional to the output frequency command. Voltage command means, means for commanding an operation mode in which the load increases, and when the command means outputs, the first voltage command means to the second voltage command means And means for switching, in which comprising means for delaying the response of the speed detector. As a result, the mechanical system and the electrical system are separated, and the possibility of vibration can be further suppressed.

Example of Invention

The rolling stock shown in Fig. 2 is a new transportation vehicle that uses rubber tires for its wheels. The drive motors 31 to 38 use three-phase induction motors arranged in each rolling stock, and the torque and speed control is VVVF.
(Variable voltage, variable frequency) This is performed by the inverter devices 101 to 104.

The relationship between the frequency f _INV of the output voltage of the inverter device and the rotation frequency f _r of the rotor of the induction motor when the three-phase induction motor is controlled by the inverter device is f _INV = f _r + f _S ……… (1) , F _S is a positive value during power running, and f _S is a negative value during regenerative braking. Also, the torque is approximately proportional to f _S.

As shown in FIG. 3, each vehicle has a drive motor 31 to 38 as shown in FIG. The drive motors have sufficient torque to accelerate each vehicle, and the rising edges of the torques also match each other, so the drive motors rotate smoothly, and the output frequency of the inverter device rises smoothly according to equation (1). , The vehicle accelerates smoothly. The output voltage is also increased in proportion to the increase of the output frequency of the inverter device, that is, the constant torque control is performed by the constant V / f control to accelerate the output voltage.

In a vehicle that performs such control, one of the inverter devices is opened due to a device failure, and the like
When running as a train with an accompanying vehicle (called 2M2T formation) or when connecting with a broken B unit in a sound 4M car with A unit The state of the vehicle and the control state are as shown in FIG.

Since the load per drive motor is twice as high as that in normal operation, the rotation of the rotor of the drive motor that outputs the driving force does not become smooth rotation, and intermittent rotation It rotates at an angle and sometimes reverses. The intermittent rotation of the drive motor causes longitudinal vibration of the electric vehicle, which eventually develops into longitudinal vibration of the entire vehicle including the accompanying vehicle through the coupler.

When the vehicle vibrates back and forth, the actual rotation of the rotor of the motor (called the rotation frequency f _r0 ) does not rotate at a constant angular velocity as shown in FIG. 5, but the rotation used for frequency control of the inverter. Since the frequency f _r is the average value of a certain unit time, there is a difference between f _r0 and f _r . As shown in FIG. 5, the inverter output frequency f _INV is f _INV = (rotational speed average value f _{r in a} certain unit time) + f _S (2). Therefore, if the actual motor rotation frequency f _r0 changes, In the diagram of "a" in FIG. 5, the slip frequency f _S becomes large and the driving torque becomes excessive, and in the diagram of "b", the driving torque becomes insufficient or the brake mode is set. That is, the slip frequency and the electric motor current are in a proportional relationship, and the vibration of the slip frequency becomes the vibration of the electric motor current as it is. If this oscillating current is negatively fed back, the motor current will diverge. Then, as the electric motor current diverges, the torque also diverges, and this torque fluctuation resonates with the longitudinal vibration of the vehicle, and the vibration further increases.

When the vibration becomes large, the difference between f _r0 and f _r becomes larger and larger, and the slip frequency becomes excessively large, and an overcurrent flows, and the overcurrent protection of the control device is activated and it becomes impossible to start.

Further, even in a healthy vehicle, these phenomena may appear even when the vehicle is started in a state where the starting torque has no margin and the required torque for each motor is large, such as when starting uphill.

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

The output of the inverter device 1 is connected to the drive motor 3 to control power running and regenerative braking. The rotor of the drive motor 3 is provided with a speed sensor 4 and a reverse detector 5
Rotor frequency f _r averaged by unit 1 speed detector 6 and unit 2 speed detector 7 after unit speed calculation
Becomes The backward movement detector 5 is a detector for performing gradient starting control for starting up in the forward direction even when the drive motor 3 reversely rotates at the time of starting uphill. The No. 1 and No. 2 speed detectors 6 and 7 are detectors having different calculation times for averaging the rotation frequency f _{r0 of the} rotor, and the No. 1 detector is short.
The No. detector is long. However, even with the No. 1 detector 6, which has a short calculation time and is fast in detection, after all it is an average value.
Since it is f _r , it does not output the true rotor frequency f _r0 . The output f _SP of the slip pattern generator 8 is added to or subtracted from the rotor frequency f _r by the inverter frequency calculator 13 through the slip frequency control calculator 12, and the inverter frequency f _INV is PW.
It is output to the M modulator 21.

With this frequency control system in common, the control voltage V _c for voltage control of the PWM modulator 21 is switched so that it can be obtained from a different control system at the time of startup and at the time of operation at an inverter frequency of 5 Hz or higher. There is.

First, at start-up, the changeover switch 20 is in the illustrated state, and the output I _MP of the motor current pattern generator 9 and the output I _M of the motor current detector 2 are compared by the first current controller 10. , The control voltage V _c corresponding to the deviation is obtained. Thus, at the time of start-up, the current control system is directly configured.

Next, when the vehicle speed (about 4 km / h) corresponding to 5 Hz or higher is reached, the changeover switch 20 is changed to the upper side in the figure, and the control voltage V _{c is changed} from the inverter output frequency command f _INV via the V / f calculator 14.
To get Further, the current control system is executed by correcting the slip frequency. That is, the current deviation is input to the second current controller 11, and a correction value corresponding to the deviation is added to or subtracted from the slip frequency pattern f _SP .

The normal control is configured as described above, and the changeover switches 17 to 20 are in the state as shown in FIG. 1 at the time of starting. Under unusual operating conditions such as when one side unit is opened in the same train or when a high-acceleration operation switch is used to rescue a failed train, the driver releases the unit release command 15 or high acceleration command. 16
Perform an operation that causes When these commands are given, switch 17 is turned on, 18 is kept open, and 19
Switch and 20 to the opposite side of the figure.

The control at this time will be described. The switch 17 short-circuits the reverse detector 5 so that the reverse detector 5 does not detect the reverse rotation start control even if the rotation of the motor instantaneously reverses. The switches 18 and 20 form an open loop current control system so that the oscillating motor current I _M is not fed back. At this time, the switching switch 20 stops controlling the inverter output voltage by the constant current control system at the time of startup, and at the same time from the time of startup,
The voltage is controlled by V / f.

Switch 19, the operation time for averaging the frequency f _r0 of the rotor is long, but to switch to No. 2 speed detector 7, the rotor frequency f _r0 to vibrate, and outputs the average value f _r of the long time It is a thing.

According to the embodiment of the present invention as described above, when the motor is started in a state where the load is larger than usual, (1) the current control system is an open loop by the driver's operation. (2) By delaying the speed detection, the mechanical system and the electrical system are separated, vibration is suppressed, and smooth startup is possible.

As a result, the riding comfort is improved, and the overcurrent operation that makes it impossible to start is eliminated.

In the above embodiment, the control system is opened as a means for suppressing the effect of the negative feedback control system, but the loop gain may be switched to a small value or the response may be delayed without opening. The same effect can be obtained by switching.

〔The invention's effect〕

According to the present invention, even if the load on each electric motor is large, the induction electric motor-driven electric vehicle can be smoothly started.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a control device for an induction motor type electric vehicle according to the present invention, FIG. 2 is a diagram showing a formation state of a vehicle, and FIGS. 3 to 5 are respectively for explaining the present invention. It is a control situation figure of an inverter device. 1 ... Inverter, 3 ... Induction motor, 6,7 ... Speed detector, 8 ... Slip frequency pattern generator, 9 ... Motor current pattern generator, 10, 11 ... Constant current controller, 12 ...
… Slip frequency correction calculator, 13 …… Inverter frequency calculator, 14 …… V / f calculator, 15 …… Unit open commander, 1
6 ... High acceleration commander, 17-20 ... Switching switch.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tsutomu Ozawa 1070 Imo, Katsuta-shi, Ibaraki Hitachi Co., Ltd. Mito Plant (72) Inventor Tetsuya Mizobuchi 1070 Ichimo, Katsuta-shi, Ibaraki Hitachi Ltd. Mito Plant (56) Reference JP-A-58-151801 (JP, A)

Claims (1)

[Claims] 1. A power converter for outputting a variable voltage / variable frequency, an induction motor fed by the power converter, a speed detecting means for obtaining a speed signal corresponding to the speed of the vehicle, and a slip frequency command. Means, and first voltage command means for outputting an output voltage command of the power converter based on a deviation between a current command of the induction motor and a motor current,
In an induction motor electric vehicle controller provided with means for obtaining an output frequency command of the power converter by addition and subtraction of the output of the speed detection means and the slip frequency command, the electric power that is substantially proportional to the output frequency command. Second voltage command means for outputting an output voltage command of the converter, means for commanding an operating mode in which the load increases, and when the command means outputs, the first voltage command means outputs the second voltage command means. The control device for an induction motor type electric vehicle, which is provided with a means for switching to the voltage command means, and means for delaying the response of the speed detecting means.