JPS627798B2 - - 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, 84, 85, 86
is a resistor, 87 is a capacitor, and 88a and 88b 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 to be in the power running or regeneration mode of operation based on the output signals of the distributor 5 and the speed control device 7, and also biases the current control device 8 when switching the mode of operation. and giving a facing signal. The rectifier 1 performs power running 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 torque corresponding to the load torque.
The output signal of the speed control device 7 is transmitted to the absolute value signal generator 1.
2, it is converted into a single polarity signal 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 ₀ 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 cosα∝V 0 as} shown in FIG.
The characteristic of Ed is 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, but a delay in the current feedback occurs when switching the 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 running mode, the DC current will not flow until the DC output voltage reaches +Ed _a , and the current control system will Dead time as td
will occur. In order to reduce this dead time, as shown in Fig. 2, in a current control device that performs proportional- _integral operation, after the current command _I At the same time as switching, the switch devices 88a and 88c are made conductive, the resistor 86 is short-circuited, the bias signal V _B is amplified with a time constant of C ₁ R ₄ , and the output signal V ₀ of the current control device is set to V ₀ =-. _{R4 / R5VB}
Set to . Thereafter, the switch device 88c is made non-conductive and the switch device 88b is made conductive to input the forcing signal V _F to the current control device.The current command I _R is also input by the absolute value signal generator 12, and the input signal V _F and I _R are amplified by the capacitor 87 in an integral action, and the output signal V ₀ is gradually increased from the set value, and the DC output voltage of the rectifier is increased to the DC voltage level on the inverter side, so that a DC current starts flowing. . The switch device 88 detects that DC current has started flowing.
a and 88b are made non-conductive, and a transition is made to a normal current control state of proportional-integral operation using the resistor 86 and capacitor 87 with respect to the current command I _R and feedback I _F.

In the conventional device, the moment the switch device 88a is changed from a conductive state to a non-conductive state, the output signal V ₀ of the current control device suddenly increases by approximately -R ₆ /R ₁ I _R , an inrush current flows, and the feedback signal I _F increases, so
There was a problem where the output signal V ₀ decreased. Therefore, the current becomes zero again, and the dead time of the current control system increases.
It was not possible to reduce td. A time chart of the output signal V ₀ of a conventional current control device is shown in FIG. 4, taking as an example the case of switching from regeneration to power running mode.

This invention was made in order to eliminate the drawbacks of the conventional ones as described above, and it provides an operational amplifier that performs integral operation, an operational amplifier that performs proportional operation, and an operational amplifier that adds their output signals. It is an object of the present invention to provide a current control device which eliminates inrush current and reduces dead time by including means for inputting a bias signal and a forcing signal to an amplifier of integral operation.

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 5, 800a, 800b, 80
0c is an operational amplifier, 801, 802, 803, 8
04,805,806,807,808,809
is a resistor, 812, 813 is a switch device, 81
4 is a capacitor.

Next, the operation will be explained. The current command I _R and the current feedback I _F are input to the operational amplifiers 800a and 800b, the operational amplifier 800a performs an integral operation, and the operational amplifier 800b performs a proportional operation. The output signal is processed by the operational amplifier 80.
0c and is added to obtain the output signal _V0 . The transfer function of the output signal V ₀ to the current command I _R is R ₁ = R ₁ ', R ₇ = R ₈ = R ₉ , then R ₆ /R ₁ × (1 + 1/SC ₁ R ₆ ), and the polarity is different. This corresponds to the transfer function of the conventional current control device as shown in FIG. 2, and has the same control characteristics during normal current control. When switching the torque direction, both the current command I _R and the current feedback I _F become zero, the rectifier and the inverter are gated off (only the inverter may be gated off), and the switch device 813 is made conductive by the signal S _B from the logic control device 10. , bias signal V _B are input. Arithmetic amplifier 800
The output signal V ₀ a of a changes with a time constant of C ₁ R ₄ , and V
_0a = -R ₄ /R ₅ V _B is set, and the operational amplifier 800
The output signal V ₀ of c becomes V ₀ =-V _0a =R ₄ /R ₅ V _B. In order to reduce the dead time, 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 running, regeneration operation mode, rotation speed, etc., it is necessary to change the bias signal V _B accordingly, but the bias signal V _B
If the accuracy is not good, inrush current may flow when the gate-off of the rectifier and inverter is cleared. Therefore, the bias signal V _B is set somewhat lower than the above level, the switch device 813 is made non-conductive at the same time as the rectifier and inverter gates are released, and the current command I _R is calculated by the absolute value generator 12. At the same time, the switching device 812 is made conductive by the signal SF from the logic control device 10 until the current starts flowing, and a forcing signal is inputted to the amplifier 800b. The output signal V ₀ increases due to the forcing signal V _F and the current command I _R , and when the current starts flowing, the switch device 812 becomes non-conductive, but the output signal V _0a of the operational amplifier 800a remains in an integral operation. Therefore, there is no change, so no inrush current occurs. The characteristics of the current control device are shown in FIG. 6, taking as an example the case where the regeneration mode is switched to the power running mode. Compared to FIG. 4, which shows the operation of a conventional current control device, the output signal V ₀ does not suddenly increase at the moment the switch device 812 is made non-conductive, and no rush current occurs, so the dead time td is considerably reduced. Ru.

In the above embodiment, the current control device may be provided with a gain adjustment device, and the operational amplifiers 800a and 800 may be connected to the non-inverting input terminal of the operational amplifier 800c.
Input the output signals V _0a and V _0b of b and output the output signal V ₀
The polarity may be the same as that of the conventional device example shown in FIG. If bipolar signals are prepared for the current command I _R and feedback I _F , the operational amplifier 8
Since 00b has a polarity reversal function, this may be omitted and a signal having the opposite polarity to the current command and feedback input to the operational amplifier 800a may be input to the operational amplifier 800c.

Although the above embodiment is an example of application to a thyristor motor device, it can also be applied when driving a DC machine with a stationary Leonard device, and the current control device of the present invention is 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, operational amplifiers that perform integral operation and proportional operation are connected in parallel to perform proportional-integral operation, and the output of the operational amplifier that performs integral operation is controlled by a bias signal. After setting, the setting value is gradually increased from the set value using the following signal, so that the device can be made inexpensive and the dead time of the current control system can be reduced.

[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, 800a, 800b, 800c... operational amplifier, 81, 82, 83, 84, 85, 86,
801, 802, 803, 804, 805, 80
6,807,808,809...Resistor, 87,8
14...Capacitor, 88a, 88b, 88c, 8
12,813...Switch device. In the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] 1. The amount of current of a motor driven by a power conversion device is determined by providing a computing unit having a proportional function and a computing unit having an integral function, and connecting both said computing units in parallel to have a proportional integral function. A current control device to be controlled includes first and second switch devices each having a function of switching a bias signal and a forcing signal input to the arithmetic unit having an integral function, and when switching the torque direction of the electric motor,
The bias signal is input to the arithmetic unit having an integral function via the first switch device and amplified by a first-order delay operation, and then the bias signal is turned off by the first switch device and the focusing is performed. The signal is input to the arithmetic unit having an integral function via the second switch device and amplified, and the second switch device turns off the forcing signal when the electric current of the motor starts flowing. A current control device characterized by: