SU478402A1 - Push pull inverter - Google Patents

Description

(54) DOOT INVERTER

f The invention relates to a conversion technique and can be used in automation and control devices. NIN for switching several galvanic-i SCR developed loads.

Two-stroke inverters are known with output transformers having a tap from the midpoint of the primary winding, in which an additional key is inserted into the power circuit of this winding, the input is connected to the control unit.

The purpose of the invention is to reduce control power.

This goal is achieved by the fact that the additional key is made semi-controlled and is connected in series with one of the primary semi-windings of the output transformer, and the second additional key is connected in series with the other primary semi-winding, the input of which is connected to the additional winding of the output transformer.

In this case, the power reduction of the control is achieved due to the fact that the control of the semi-controlled key occurs

once per period for a time less than half the period.

The drawing shows a two-stroke inverter circuit.

The push-pull inverter contains an output transformer 1 and power semiconductor switches 2 and 3, the control inputs of which are connected to the source of the reference voltage 4, and the power outputs through additional semiconductor switches 5 and 6 - cti primary transformers 1 of the transformer 1.

The control input of the key 5 is connected to the control unit 7 with a two-position characteristic, and the control input of the key 6 is connected with the additional winding 8 of the output transformer 1. The dot-breakpoint and number 9 denote output stages of two-stroke inverters that can be in complex control systems.

Push-pull inverter works as follows.

Due to antiphase voltages of source 4, power semiconductor switches 2 and 3 are opened alternately. If the output signal of the control unit 7 is small, then the key 5 is closed and the current through the left half winding of the output transformer 1 does not flow. No current flows through the right primary half winding of the output transformer 1, since there is no change in the magnetic flux in its core, there is no voltage on the auxiliary winding 8, and there is no current through the control switch 6.

With a large control signal of the governing unit 7, the key 5 opens and in one of the half periods of the reference voltage, when the power switch 2 is open, the left primary half winding of the output of the transformer 1 is under the voltage of the power supply. At the end of this half cycle, the voltage from the left primary semi-winding is removed.

Due to the self-induction of the output transformer 1 on its additional winding 8 occurs e. D. s., under the action of which the current flows through the control transition key 6, which opens this key. Since the power switch 3 is open from this moment, then in the second half-period of the reference voltage, the primary winding of the output transformer 1 will be connected to the power source. As a result, with a large output signal c. The control unit 7 at the output windings of the transformer 1 forms perembnoe voltage.

The push-pull inverter also forms the output voltage in the case of control. MI from the control unit 7 is a variable voltage in-phase with a reference voltage at the input of the switch 2, which allows its use in phase-sensitive devices.

The use of a thyristor (or a thyristor optocoupler) as 5 allows one to turn on the output stage 9 of a push-pull inverter with short pulses from the control unit 7.

One pair of power switches 2 and 3 allows you to connect to it the required number of identical output stages 9 in complex control systems.

Using two output stages 9 with different output characteristics

The control units 7 allows you to simply implement a three-position device with an output on alternating voltage or constant voltage, if you use straight-through voltage in the output winding circuits.

As keys 2, 3, 5 and 6, in addition to transistors, thyristors or thyristor optocouplers can be used. In this case, it is necessary to provide thyristor switches 2 and 3.

The use of thyristors in keys 5 and 6 does not require quenching circuits, since (the circuit of the current is opened by keys 2 and 3.

Subject invention

Push-pull inverter with an output transformer having a branch from the midpoint of the primary winding containing dOg. An additional key in the circuit of this winding, the input of which is connected to a control unit, characterized in that, in order to reduce control power, the additional key is made semi-contracted and connected in series with one of the primary half windings of the output transformer, and the second additional one is connected in series with the other primary half winding a key whose input is connected to the auxiliary winding of the output transformer. B. -j C.