JPS627797B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a current control device for controlling the amount of current in a thyristor motor device, a static Leonard device, or the like.

Conventionally, there has been a thyristor motor device using this type of device as shown in FIG. 1 is a rectifier, 2 is an inverter, 3 is a DC reactor, 4
is a synchronous motor, 5 is a distributor that detects the position of the rotor of the synchronous motor 4, 6 is a finger speed generator that detects the rotation speed of the synchronous motor 4, 7 is a speed control device, 8 is a current control device, and 9 is a a gate signal generator for rectifier 1;
10 is a logic control device that generates a gate signal for the inverter 2; 11 is a current detector that detects a signal similar to the direct current of the rectifier 1; and 12 is an absolute value signal generator. In FIG. 1, the current control device 8 was as shown in FIG. 2. In the figure, 80 is an operational amplifier, 81, 82, 83 are resistors, 84 is a capacitor, and 85a, 85b are switch devices.

Next, the operation will be explained. The inverter 2 is a separately excited inverter commutated by the induced voltage of the synchronous motor 4, and the conduction phase is determined by the logic control device 10. The logic control device 10 controls the conduction phase of the inverter 2 so as to be in the drive mode or the regeneration mode based on the output signals of the distributor 5 and the speed control device 7, and also resets the current control device 8 when switching the mode of operation. , provides bias and forcing signals. The rectifier 1 performs a regenerative or regenerative operation in response to switching of the operation mode of the inverter 2, and controls the amount of DC current so that the synchronous motor 4 generates a torque corresponding to the load torque. The output signal of the speed control device 7 is converted into a single polarity signal by the absolute value signal generator 12, and becomes the current command I _R of the current control device 8. The feedback signal I _F of the current control device 8 is detected by the current detector 11 as a direct current amount, and is a signal having a polarity different from that of the current command I _R . The output signal V _p of the current control device 8 is applied to the gate signal generator 9 of the rectifier 1 . For example, the input/output characteristics of the gate signal generator 9 are such that the phase control angle α is cosd∝V _p as shown in FIG. 3a, and the characteristics of the output signal V _p and the output voltage E _d of the rectifier 1 are It becomes a straight line as shown in Figure 3b. The current control device 8 controls the current command I _R so that the feedback signal I _F becomes equal to the current command I R.
A delay in current feedback occurs when switching torque direction. For example, during regenerative operation, when the DC output voltage of rectifier 1 is -Ed _a , if the mode is suddenly switched to power mode, the DC current will not flow until the DC output voltage reaches +Ed _a , and the current control system This will result in dead time. In order to reduce this dead time, in a current control device that performs integral operation as shown in Fig. 2, a current command I
After _R and the feedback I _F become negative, the conduction phase of the inverter 2 is switched, and at the same time, the switch device 85a is made conductive to short-circuit the capacitor 84, and the output voltage V _p of the current control device becomes negative. Thereafter, the current command _I
5a is made non-conductive, the switch device 85b is made conductive, and the forcing signal V _F is input to output the output signal V _p
By gradually increasing the DC output voltage of the rectifier to the DC voltage level on the inverter side, DC current begins to flow. The switch device 85b was made non-conducting by detecting that the direct current began to flow. Output signal V _p of conventional current conditioning device
FIG. 4 shows a time chart of the case of switching from regeneration to power mode as an example.

In the conventional device, in order to reduce the dead time _td of the current control system, a forcing signal _VF is input, and the dead time is adjusted by changing the forcing signal _VF . In order to perform sampling characteristics having an average dead time of 1/2n, if the time rate of change of the output signal V _p of the current control device is not limited, an inrush current may occur, and there is a limit to reducing the dead time. n is the number of rectifier phases, and is the power supply frequency. In Fig. 4, E _d is the DC output voltage, S _B1 is the ON signal of S _W1 , and S
_F is the ON signal of _SW2 , and _gp is the gate OFF signal.

This invention was made in order to eliminate the drawbacks of the conventional ones as described above, and it provides a bias signal and sets the output signal V _p to a certain value.
It is an object of the present invention to provide a current control device that inputs a forcing signal V _F to eliminate inrush current and reduce dead time.

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 5, 80 is an operational amplifier having a proportional function, 81, 82, 83, 85, 86 are resistors, 84 is a capacitor, and 85b, 85c are switch devices.

Next, the operation will be explained. At the time of torque direction switching, both the working flow command I _R and the feedback I _F become negative, the rectifier and the inverter are gated off (only the inverter may be gated off), and the switch device 85c receives the signal S _B3 from the logic control device 10.
conducts, and the bias signal V _B is input.
The output signal V _p changes with a time constant of C ₁ R ₄ and is set to V _p =R ₄ /R ₅ V _B. In order to reduce the dead time t _d , this set value may be set to the DC output voltage level of the rectifier when a steady current flows. Since this DC output voltage level changes depending on factors such as power line, regenerative operation mode, rotation speed, etc., it is necessary to change the bias signal V _B accordingly, but the accuracy of the bias signal V _B is not good. Inrush current may flow when the rectifier and inverter gates are turned off. Therefore, the bias signal V _B is set to a level slightly lower than the above level to set the output signal, and at the same time the gates of the rectifier and inverter are released, the switch device 85c is made non-conductive, and the absolute value of the current command I _R is generated. At the same time, the switching device 85b is made conductive by the signal S _F from the logic control device 10 until the current starts flowing, and the forcing signal V _F is input. Since the increase in the output signal _Vp caused by the forcing signal _VF can be small, the time rate of change can be smaller than that of conventional devices, so there is no inrush current, and dead time in the current control system can be reduced. . The operating characteristics of the current control device are explained in the sixth section, taking as an example the case of switching from regeneration mode to power mode.
As shown in the figure. The fourth diagram shows the operation of the conventional current control device.
Compared to the figure, the time rate of change of the output signal V _p becomes smaller, and no inrush current occurs.

Note that in the above embodiments, a gain adjustment device may be provided in the current control device. Further, the current feedback input section may be provided with a device for performing a differential operation.

The above embodiment is an example of application to a thyristor motor device, but it can also be applied when driving a DC machine with a stationary Leonard device, and the current control device of the present invention can be used when switching a bidirectional rectifier in response to switching the torque direction. , the dead time of the current control system can be reduced.

As described above, according to the present invention, after the output signal is set by the bias signal, the output signal is gradually increased from the set value by the following signal, so that the device can be made inexpensive and the dead time of the current control system can be reduced. There is an effect that can be obtained by reducing.

[Brief explanation of the drawing]

Figure 1 is a block diagram showing the configuration of a conventional speed control circuit for a thyristor motor, Figure 2 is a circuit diagram showing the configuration of a conventional current control device, and Figure 3a is a phase angle characteristic showing the operation of a gate signal generator. Figure 3b is a DC output voltage characteristic diagram showing the operation of the gate signal generator and rectifier, Figure 4 is a time chart showing the operation of the conventional current control device, and Figure 5 is according to an embodiment of the present invention. A circuit diagram showing the configuration of a current control device,
FIG. 6 is a time chart showing the operation of this invention. In the figure, 1... Rectifier, 2... Inverter, 3... DC reactor, 4... Synchronous motor, 5... Distributor, 6...
Finger speed generator, 7... Speed control device, 8... Current control device, 9... Gate signal generator, 10... Logic control device, 11... Current detector, 12... Absolute value signal generator, 80... Arithmetic amplifier ,81,82,83,8
5, 86...Resistor, 84...Capacitor, 85a,
85b, 85c...Switch device. In the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. In a current control device that controls the amount of current of a motor driven by a power conversion device by a computing unit having an integral function, a first control device having a function of switching a bias signal and a forcing signal input to the computing unit, respectively. and a second switch device, when switching the torque direction of the electric motor, the bias signal is input to the arithmetic unit via the first switch device and amplified by a first-order lag operation, and then the bias signal is amplified by a first-order lag operation. The first switch device turns off the switching device, and the forcing signal is input to the arithmetic unit via the second switching device, and when the electric current of the motor starts flowing, the second switching device inputs the forcing signal to the computing unit. A current control device characterized in that the current control device is configured to turn off the current control device.