SU834821A1 - Transistorized converter - Google Patents

Description

(54) TRANSISTOR CONVERTER

I

The invention relates to electrical engineering and is intended for use in secondary power supplies.

Circuit solutions of transistor converters (inverters) are known, which make it possible to limit the saturation of the transformer core of said converter and thereby reduce the currents flowing through the inverter power transistors when the transformer core 1 is saturated.

The closest in technical essence to the present invention is a transistor, a converter containing a medium point transformer connected to one of the wiring of the converter power source, power transistors, emitte. The pins of which are interconnected, a resistor connected between the common emitter point of the s. transistors and the second length of the specified power source, an auxiliary transistor, the base-emitter junction of which is connected in parallel with the specified resistor and the locking circuit of the power transistors connected to the bases of the power transistors .

However, in this circuit it is not possible to obtain an effective limiting of the current of an open power transistor when the transformer is saturated, i.e. the small difference between the limiting current and the operating current of the transformer.

The purpose of the invention is to increase the reliability of the converter.

The goal is achieved by the fact that in the transistor converter the locking circuits are made on two control transistors and an additional source of direct voltage, the emitter of the auxiliary transistor is connected to the common point of the emitters of power transistors, the base of this transistor is connected to the specified power source, The bases of the specified control transistors are connected through dividing resistors to the auxiliary transistor collector, the collector of each control trazistor is connected to ene respectively to the base of one of the power transistors and the emitters of transistors actuating subkey, one of us Shin additional voltage source, whose second ness

connected to the second power supply bus of the converter.

The drawing shows a schematic diagram of the proposed Converter.

The converter contains power transistors 1 and 2, the base-emitter transitions of which are shunted by diodes 3 and 4, respectively, and the emitters are interconnected. Transformer 5 has two collector windings b and 7 connected in series and connected by a common point to the positive bus of power supply 8, and opposite terminals to collectors of power transistors 1 and 2, and base winding 9 connected through a ballast resistor 10 to bases of power transistors. Resistor 11 is connected between the power transistor emitters () points 1 and 2 and the minus bus of the power supply 8. The auxiliary transistor 12 is connected by the emitter to the open, to it the point of the emitters of the power transistors, and the base to the minus bus of the power supply 8. The control transistors 13 and 14 have integrated emitters, and their bases are connected through separation resistors 15 and 16 to the auxiliary transistor collector 12. The collector of the first control transistor 13 is connected to the base of the first power transistor I, and the collector of the second control transistor 14 to the base second power tr; p1zspstor. 2. An additional source 17 of direct voltage, built on one of the output transistor 18transformer wires 5, the negative bus is connected to the common emitter point of the control transistors 13 and 14, and the positive shield is connected to the negative terminal of the power supply 8.

The device works as follows.

When the supply voltage is applied, the converter starts working like a normal Royer multivibrator. To improve the launch, any of the known trigger schemes are used.

Suppose that after supplying power, a current begins to flow through the power transistor 1. Then a voltage appears on the winding 9, keeping the transistor in the open state. At the same time, a voltage appears on the output winding 18 and on the wiring of the additional voltage source 17. As long as the transformer 5 sfdetec is unsaturated, the current flowing through transistor 1 and resistor 11 is determined by the load on the converter. The magnitude of the resistor 11 is chosen so that over the entire load range of the inverter with an unsaturated transformer core 5, the voltage drop across the resistor is not sufficient to open the auxiliary transistor 12, which

when this is closed, the control transistors 13 and 14 are also closed. When the core of the transformer 5 begins to saturate, the current through the transistor 1 and the resistor 11 increases sharply. The current flowing through the resistor 11 reaches the value at which the auxiliary transistor 12 opens, while the control transistors 13 and 1, the minus of additional source 17 is connected to the base of the power transistor 1 and occurs

the process of actively locking up this transistor, the duration of which is determined by the resorption time of the minority carriers in its base.

In order for the specified process to begin, the control transistor 13 and the auxiliary 12 must not go into saturation mode, which also significantly shortens the locking time of the power transistor 1.

After locking the power transistor, the voltage on the winding 9 of transformer 5 is reversed and the power transistor 2 opens, after which the described process repeats.

Claims (2)

1. Yurchenko L.I., Golovatsky V.A. and Kartaev P.I. Transistor Transducers with Direct Mode Control remagnetization of a transformer .- "Electronic equipment in automation, vol. 10, s. 118-121. 2. US Patent No. 3781638, cl. publish 1974.