SU907530A1 - Stabilized electric power supply source - Google Patents

Description

The invention relates to electrical engineering and can be used in secondary power sources. A stabilized DC voltage converter is known that contains / drives a generator, a pulse-width modulator connected via a voltage-controlled voltage to the transistors of a power amplifier, to the output of which a load is connected via a rectifier with filter. A disadvantage of this device is the lack of forced latching of transistors of a power amplifier. The closest to the invention is a stabilized power source containing a power amplifier and a master oscillator with an output transformer, the secondary coils of which are connected to the power inputs of the resistors of the power amplifier through basic resistors. , a co-mutation unit with the first and second pair of output terminals and the control transistor, the co-collector of which is connected to the output of the gate. and the base is connected to the input terminal of the switching unit, where the first and second pair of output terminals of the switching unit are connected between the base of one power transistor and the connection point of the base resistor of the opposite power transistor and the output side of the secondary transformer of the master oscillator, and the input terminal of the switching unit is connected to the output of pulse width modulator 2. A disadvantage of the known stabilized source is a decrease in the efficiency with an increase in the output power of the device. The purpose of the invention is to increase the efficiency and expand the functionality of the device. This goal is achieved by the fact that in a known stabilized power supply, said switching unit is equipped with an additional transformer, the primary windings of which through diodes are connected to the corresponding pairs of output terminals, and the secondary winding to the input of said rectifier. The drawing is a schematic diagram of a power source. The stabilized power supply comprises a master oscillator 1 with an output transformer 2, the secondary windings of which are connected to the inputs of power transistors 3 and 4 of the power amplifier. The first 5 and second 6 pairs of output terminals of the switching unit 7 are connected between the input circuits of the power transistors 3 and 4, and the INPUT terminal 8 is connected to the output of the comparator 9, which together with the sawtooth 10 and the DC amplifier 11 forms a pulse-width pulse modulator The primary windings 12 of the auxiliary transformer 13 through diodes 14 and 15 are connected to the output terminals of the unit 7, and the secondary winding 16 to the input of the rectifier 17 whose output is bridged by the control transistor 18. The power of the pulse-width modulator is supplied from the rectifier 19 and the power of the master oscillator 1 is from the parametric stabilizer 20. A load 21 is connected to the output of the power amplifier.

The master oscillator 1 generates rectangular-voltage voltage pulses that are stable in frequency and amplitude. As windings of a transformer 2, connected through resistors to the inputs of power transistors 3 and 4, basic windings of transformer 2 of master oscillator 1 can be used. In the open state of key 18, the magnetic circuit of transformer 13 is re-magnetized by the voltage applied to one of the primary windings :

11 where and is the voltage on the primary winding of the transformer 13;

and - voltage on saturated

bd

transition emitter base

transistor 3; and - base winding voltage

transformer 2; and - voltage drop on open diode 14.

Since the secondary winding of the transformer 13 is open, the current flowing through the diode 14 and the primary winding 12 is small equal to the no-load current. When the key 18 controlled by the comparator 9 is closed, the voltage drop across the primary winding 12 of the transformer 13 becomes (, -,) / K, where K is the transformer transfer coefficient, UKH the voltage on the saturated transistor 18, U-if the voltage rfa diode 1X rectifier 17. The current, the flowed electrode at this time across the secondary winding of the transformer 13, is less in K and, since the value of K can be chosen sufficiently large (10-20), the control of the transistor 18 is performed directly from the output of the comparator 9 while providing rich state of the transistor 18.

The potential of the base of the closed transistor 3 is negative () even at sufficiently small voltages on the base winding I, 1.5 - 2 V, therefore the conditions for locking the power transistors do not impose any restrictions on the choice of voltage on the base windings of the transformers 2.

The presence of the rectifier 19 connected to a separate winding of the transformer 2 is not necessary, since the power of the pulse-width modulator can be supplied from the output of the device, however, it becomes difficult to build a unified control circuit of the converter for different ratings of output voltages.

Thus, the proposed technical solution allows increasing the efficiency of the device and expanding its functionality- (saving the forced locking of power transistors and galvanic isolation without using optocouplers, which limited the temperature range and radiation resistance of the stabilizer

Claims (2)

1. The author's certificate of the USSR 527808, CL N 02 M 3/335, 1973. 2. USSR author's certificate for application No. 2807725/07, cl. G 05 F 1/64, 06.08.79.