SU1372559A1 - D.c. to d.c. converter - Google Patents

Abstract

This invention relates to the field of electrical engineering. Pel - increase reliability by simplifying the circuit. With a load current, which means that the current idle is higher than the current transformer, self-oscillations occur in the converter due to positive current feedback. In this case, the power transistors in turn open, allowing current to flow into the load. With a low load current, alternate opening of the power transistors is provided due to relaxation oscillations in the control circuit. The opening of the power transistor 1 occurs when the capacitor 13 is charged through the resistor 11 and the winding 8, 9, and the opening of the power transistor 2 occurs due to the discharge of the capacitor through the winding 8 and the transistor 10 opened by the flow of the base current from the winding 9. 1 Il. (L

Description

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The invention relates to a converter technique.

The purpose of the invention is to increase reliability by simplifying the circuit.

The drawing shows a diagram of the Converter.

The converter contains power transistors 1 and 2, a current transformer 3 with primary winding A, 5 and windings 6 and 7 of positive feedback, an additional 8 and auxiliary 9 windings.

Transistor 10 (controllable key) is connected to the beginning of the winding 8 and through a resistor 11 to the first input terminal. The end of the auxiliary winding 9 through a resistor 12 is connected to the base of the transistor 10. The connection point of the additional 8 and auxiliary 9 windings through the capacitor 13 is connected to the emitter of the transistor 10 and the second input terminal. The current to the load 14 flows through the power transistor 1 and the winding 4 or the power transistor 2 and the winding 5 of the transformer

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The Converter operates as follows.

When power is applied to the converter along the circuit, resistor 11 - winding 8 - capacitor 13 begins to flow a current, which creates an EMF in the windings of the current transformer, and on winding 9 - in polarity, which locks the transistor 10 EMF on windings 6 and 7 unlocks the power transistor 1 and locks the power transistor 2. Through the opening of the power transistor 1 and the winding 4 of the current transformer, a load current begins to flow, which, due to the positive feedback, tends to keep the power transistor 1 open. winding 4 in Hank ob- 6 exceeds the power transformable from windings 8 and 9, the inverter having self oscillation, as determined by the positive feedback of the load current. The self-oscillation parameters weakly depend on the state of the transistor 10 and are mainly determined by the magnitude of the magnetizing currents of the windings 4 and 5 and the gain of the power transistors 1 and 2.

If the load current is small and not enough to maintain self-oscillations in the converter, the open

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This transistor 10 is maintained only by the charge current of the capacitor 13. As the charge progresses, the voltage on it grows and begins to exceed the blocking voltage on winding 9, which leads to the opening of transistor 10 and a decrease in the voltage on its collector. As a result, the voltage polarity changes abruptly on the transformer windings. The capacitor 13 begins to discharge through the winding 8 and the transistor 10, which is maintained open and valued due to the base current from the winding 9 through the resistor 12. By changing the polarity of the voltage on the windings, the power transistor 1 opens and the power transistor 2 opens. Through the open transistor 10 simultaneously with the discharge current of the capacitor 13 a current flows, which is determined by the value of the supply voltage and the resistance of the resistor 11.

As the capacitor discharges, the voltage across it and the secondary winding 8 decreases and the base current of the transistor 10 also decreases. Therefore, the moment comes when the transistor 10 goes out of place, the voltage on its collector begins to increase, causing an avalanche-like process of reversing the voltage on the current transformer windings, locking the transistor 10, the power transistor 2 and unlocking the power transistor 1.

Next, the capacitor 13 begins to charge through resistor 11, i.e. the next self-oscillation period of the converter begins.

The converter eliminates the need for automatic control circuits. By reducing the number of elements of the converter circuit, its reliability is increased.

Claims (1)

Invention Formula The DC / DC converter containing the power transistors, whose power circuits are connected to the input terminals through the primary windings of the current transformer and the output terminals, the positive current-feedback windings of the current transformer are connected to the rods of the power transistors, the control key, 31372559. the power circuit of which is connected to reliability reliability by simplifying the circuit outputs through the first resistor, the opposite of the second output is dopoltor, the first output of which is the connecting winding and the first output The first input terminal and the second secondary winding transformer output are connected to one of the current leads Rz and are connected via the additional winding transformer capacitor connected to the current rammer, auxiliary winding circuit of the controlled key, which through the second resistor for its output and control guide connected to the control input of the up-circuit, with the second output of the auxiliary key, the differential winding connected to the output u and with the fact that, in order to increase the second resistor.