SU961032A1 - Protected solid-state converter - Google Patents

Description

. This invention relates to the protection of power sources.

A transistor converter with protection is known, which contains an inverter with an output transformer, a rectifier, a threshold organ with a transistor, and an automatic recloser unit on the pulse generator 1.

A disadvantage of this device is the lack of protection for the output current and voltage, which limits its functionality.

The closest to the proposed technical essence and the achieved result is a transistor converter with protection, containing an inverter with a block. control connected to the power source through a transistor, the input circuit of which is connected with the secondary winding of the inverter output transformer, the prohibition unit and the inverter output current sensor connected to the threshold organ 2.

A disadvantage of the known device is the limited functionality due to the lack of current protection and AR.

The purpose of the invention is to expand the functionality.

This goal is achieved by the fact that the converter is equipped with a rectifier and a zener diode connected between the transformer and the input circuit of the transistor, connected to the output of the start-up unit and the output circuit of the threshold organ, and the start-up unit is performed on the pulse generator with an RC circuit and an additional transistor whose input circuit connected to the output of the rectifier, and the output circuit is connected parallel to the capacitor of the RC circuit.

FIG. 1 shows the scheme of the proposed converter; in fig. 2 - the same, option.

The converter contains (FIG. 1) an inverter 1 with a control unit 2, a transistor 3,

20 transformer 4, expander 5, resistor 6, zener diode 7, start-up unit 8 containing controlled contact 9, capacitor 10 and resistors II, 12, output current sensor 13

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inverter, the threshold body 14 with a switching, output circuit 15, the load 16.

The converter is triggered by closing the contact 9. At the same time, the charge current of the capacitor 10 flows through the resistor 11 and the starting circuit of the transistor 3, which opens, and the supply voltage goes to the unit 2, the output voltage of which goes to the input of the inverter 1, and the output the voltage of the inverter through the transformer 4, the rectifier 5, the resistor 6, the zener diode 7 is fed to the input of the transistor 3, keeping the latter in the open state after the start-up pulse (full charge of the capacitor 10). Opening contact 9 causes the capacitor 10 to discharge through a high-resistance resistor 12.

When a short circuit occurs in the load circuit 16, the transistors of the inverter 1 go out of saturation, the voltage drop across them increases, and the output voltage of the inverter decreases and the input current of the transistor 3 decreases. Transistor 3 exits saturation mode, causing a decrease in the power supply voltage, unit 2, the output voltage of which decreases even more, which ensures an avalanche-like disconnection of the inverter transistors. Due to the presence of the Zener diode 7, the transistor 3 is closed, with a relatively small decrease in voltage at the output of the inverter, which increases the speed of protection. With a gradual increase in the load current, the output signal of the sensor 13 increases, at a certain value of which is less than the maximum current of the inverter, the body 14 is triggered and its output circuit 15 shorts the input circuit of transistor 3, as a result of which the converter turns off.

Starting the converter after the elimination of the short circuit caused the device to re-close the contact 9. To perform an automatic restart

(Fig. 2) the startup unit 8 is executed on a pulse generator containing a single junction transistor 17 and an RC chain, on a capacitor 18 and a resistor 19, an additional transistor 20 and a resistor 21. When the converter is not working, the voltage at the output of the rectifier 5 is absent, the transistor 20 is closed, and the capacitor 18 begins to charge. When the voltage across it reaches a certain value, transistor 17 opens. The capacitor 10 is discharged through the input circuit of transistor 3 and the converter is restarted. After starting the converter and the appearance of voltage at the output of the rectifier 5, the resistor 12 opens, preventing the charging of the capacitor 10, and the supply of start-up pulses to the input of transistor 3 is stopped.

The device has advanced functionality.

Claims (2)

1. USSR author's certificate according to the application 2511057 / 24-07, cl. H 02 H 7/12, 1977. 2. USSR author's certificate for application No. 2604806 / 24-07, cl. H 02 M 1/18, 1978 W ABOUT 1