RU1829092C - Device to switch on power thyristor - Google Patents

Abstract

Summary of the invention: when the contacts of the closing contact group are open and the opening and switching contacts of the switching contact group are closed, the capacitor 5 is charged through the resistor 12 and diode 6. When the contact groups of the switch are switched, the discharge of the capacitor 5 to the optocoupler 8 LED starts negative, with respect to the turn-on polarity of the thyristor 1, the half-wave of the supply voltage, which enables the thyristor to be turned on with the help of an optocoupler photothyristor 8 when the network voltage Wife through zero. 1 C.p. f-ls, 1 ill.

Description

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with

The invention relates to electrical engineering and can be used to turn on a thyristor for a fixed number of integer half-cycles of the supply voltage.

The purpose of the invention is to increase reliability and expand the functionality of the device.

The drawing shows a schematic diagram of the proposed device.

The device for turning on the power thyristor 1, the anode of which is connected to the first terminal 2 of the AC network, with the second terminal 3 of which the first output terminal of the load 4 is connected, the second terminal of which is connected to the cathode of the power thyristor 1, contains a capacitor 5, diode 6, a switch with a closing and switching 7.1 and 7.2 contact groups, two optocouplers 8 and 9, three resistors 10-12, current limiter 13. The cathode of the optocoupler 8 of the optocoupler through a resistor 10 is connected to the control electrode of the power thyristor 1, and the anode to the anode of the power thyristor 1 and one conclusion ohm of the resistor 12, the other terminal of which is connected to the opening contacts of the switching contact group 7.2 of the switch, the switching contact of which is connected to the first output of the capacitor 5, and the making contact is connected to the first output. which is connected to the anode of the photothyristor of the optocoupler 9, the cathode of which is connected to the second output of the capacitor 5 and the anode of the diode 6, the cathode of which is designed to connect to the first output of the load 4. The cathode is light iodine photocoupler 9 through the closing contacts of the contact group 7.1 is connected to the anode and cathode thereof through the resistor 11 - to the cathode of the power thyristor 1.

The current limiter 13 can be made in the form of a current stabilizer, for example, on a field effect transistor 14 and a resistor 15.

The device operates as follows.

Let AC network be connected to terminals 2 and 3, the capacitor 5 will quickly charge with unipolar pulses along the circuit; terminal 2 - resistor 12 - disconnect contacts of the switching contact group 7.2 - diode 6 - terminal 3.

When the switch is moved to another position, the closing contacts of the contact groups 7.1 and 7.2 are closed. The cathode of the optocoupler LED 9 is connected to the anode of the power thyristor 1 and lights up at a negative half-wave voltage.

The optocoupler thyristor 9 is turned on and the capacitor 5 starts to discharge the make contact of the switching contact group 7.2 - current limiter 13 optocoupler LED 8 - optocoupler thyristor 9. Under the influence of the discharge current, the optocoupler LED 8 lights up and gives a command to turn on its photothyristor. As soon as the voltage at the anode of the power thyristor 1

0 starts to move from the region of negative to the region of positive values, the optocoupler thyristor 8 is turned on, which transmits a pulse generated by the thyristor 1 control electrode

5 of its anode voltage. Thyristor 1 is turned on, passing the positive period of the supply voltage to load 4. Since the voltage drop across the open thyristor 1 is small, no current flows through phototistor 8, which reduces the heating of thyristor 1, and power loss. In the negative half-cycle of the mains voltage, the thyristor 1 is disconnected, disconnecting the load from the mains. Subsequent positive

5, the half-cycle of thyristor 1 opens as described above.

The conductivity of thyristor 1 by the number of full half-periods is determined by the charge energy of capacitor 5. As

0 discharge of the capacitor 5, the current decreases through the LED of the optocoupler 8 and when it reaches a value less than the minimum current of the LED of the optocoupler 8, it goes out, its photo thyristor, thyristor 1 closes

5

turns off when the current flows through it

zero. Moreover, at all positive half-periods of the supply voltage, the thyristor 1 turns on with a practically constant control angle close to

0 to zero.

To reduce the required capacitance of the capacitor 5, the current limiter 13 can be made in the form of a current stabilizer assembled, for example, on a MOS transistor 14, a resistor 15, which in addition increases the reliability of the device by stabilizing the current through the emitting LED.

Thus, the proposed device allows to increase reliability and improve its overall dimensions and energy by opening the power thyristor with short pulses formed from its anode

5 voltage, with a control angle close to zero, a small capacitance of the time of the driving capacitor, separation of its charge and discharge circuits, stabilization of the current in the discharge circuit, minimal power loss in the resistors of the control circuit.

Claims (2)

1. Device for turning on the power thyristor, the anode of which is connected to the first terminal of the AC mains, with the second terminal of which the first load terminal is connected, the second terminal of which is connected to the cathode of the power thyristor, containing a capacitor, a diode, a switch with a closing and switching contact groups, the first and second resistors and the first optocoupler, the cathode of the photo-thyristor of which through the third resistor is designed to switch the control electrode of the power thyristor, characterized in that, in order to increase over To improve operation and expand functionality, a current limiter and a second optocoupler are introduced, the LED input of which is designed to be connected through the second resistor to the cathode of the power thyristor, and the cathode is connected to the first contact of the closing contact group of the switch, the second contact of which is designed to connect to the anode a thyristor and is connected to the anode of the photothyristor of the first optocoupler and the first output of the first resistor, the second output of which is connected to the opening contact of the switching contact switch groups, the switching contact of which is connected to the first output of the capacitor, and the make contact is connected to the first output of the current limiter, the second output of which is connected to the anode of the photodiode of the first optocoupler, the cathode of which is connected to the anode of the photothyristor of the second optocoupler, the cathode of which is connected to the second output of the capacitor and the anode a diode whose cathode is intended to be connected to a first load terminal. 2. Device pop. 1, characterized in that the current limiter is made in the form of a current stabilizer.