SU280632A1 - STABILIZED CONSTANT VOLTAGE TRANSFORMER - Google Patents

Description

Stabilized and transformers are known; kei-ies containing a device with auto-geo-feedback and a variable duty cycle of the generated voltage determined by the feedback circuit.

The proposed converter differs from the known ones in that the blocking-generator transformer is made with an additional winding connected to the emitter of the control transistor through the diodes and with the average output of the primary winding. ;

This provides a use as a regulating element of the transistor with a low and, at times, admissible reverse voltage, a base-emitter junction.

Pa drawing shows the basic electrical circuit and the proposed converter.

The control element of the converter is a high-power transistor 1 operating in a key mode according to a blocking oscillator circuit. The blocking generator transformer 2 simultaneously performs the functions of a magnetic energy storage. It contains a collector winding 3, a base winding 4, a feedback winding 5, a load winding 6, an additional winding 7. The capacitor 8 is a blocking generator capacitor.

Transistors 9 and W control a transistor / and are connected in a composite circuit. The resistance 11 sets the current to the base of the transistor 10, and the resistance 12 limits the collector current of this transistor. The diode 13 prevents the flow of the driving current from the power supply to the circuit through the base-collector of the transistor 9 to the minus of the power source. Diode 14 compensates for zero

the collector current of the transistor 10. The output filter, consisting of a capacitor 15 and a diode 16, operates at a load 17. The diode 18 rectifies a surge voltage applied to a comparison with a reference voltage source, which is a zener diode 19. The capacitor 20 is It is a filter capacitor. Diodes 21 and 22 disconnect the additional winding 7 of the transformer 2 during the formation of a blocking pulse, and also prevent the flow of the starting current when the power is supplied to the circuit through the additional winding to the minus of the power supply.

Works proposed scheme as follows.

The input DC voltage, varying in magnitude, is supplied through the regulating transistor to the winding 3 of the transformer 2. The transistor / operates in the key mode according to the blocking generator circuit. In the base

the voltage holding the transistor / in the open state.

During the formation of the pulse of the blocking generator, the additional winding 7 is disconnected due to the diodes 21 and 22. The current of the collector winding 3 line1 increases with time. As soon as the current of the collector winding 3 reaches a certain maximum value, the base current of transistor 1 will not be enough to maintain the blocking process, and the transistor / will start to lock on the base. The formation of the emission begins.

By the time the blocking process terminates, the current flowing in the winding 3, having reached a maximum, has abruptly ceased. Magnetic notes in the transformer 2 can not disappear abruptly, so a current is generated in the load winding 6 during a spin (ejection), which through diode 16 enters the load 17.

Thus, in contrast to the known blocking generators, in which the duration of the pause between successive pulses of the blocking generator is determined by the time of the driving RC chain, in the described blocking generator, the duration of the pause is determined by the discharge current time of the load winding 6 on load / 7.

The magnitude of the accumulated energy depends on the switching frequency of the key and on the ratio of the duration of the states "closed and open". The voltage supplied by the feedback winding 5 is rectified by diode 18 during the emission and compared with the voltage of the reference voltage source - Zener diode 19. The error terminal is transmitted through the feedback amplifier (transistors 9 and 10) to the base of the transistor / and controls the key switching frequency. K.d. The converter depends only on the quality of the parts used and is practically independent of the input voltage range.

A nanoparticle blocking the transistor (during ejection) is supplied from the auxiliary winding of the transformer. Locking voltage value is equal to voltage difference.

on the additional winding during the surge and voltage drop across the diodes 21 and 22, ti is chosen to be less than the maximum permissible reverse voltage of the base-emitter transition of the transistor /. Thus, in the onisable circuit, it is possible to adopt as a regulating transistor with any very small reverse voltage base-emitter junction.

Since, according to the operating principle of the circuit, the surge voltage is stable with changes in the input voltage, then the blocking voltage generated by the additional winding is also stable.

The capacitor 8 serves to provide an avalanche-like process of forming the fronts of the pulse generated by the blocking generator. The use of two diodes 21 and 22 at once is necessary to prevent the base-emitter of the transistor from bridging the additional winding of the junction circuit / during circuit startup when it is turned on. If transistor / silicon, then diodes 2} and 22 should be

also silicon. At low starting currents, the voltage of the opening of two banks connected in series is greater than the opening of the base-emitter junction of the transistor.

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Subject invention

A stabilized DC converter, containing a regulating transistor, whose collector is loaded on the middle winding of a blocking generator transformer, and the base on the average output of the primary winding of the same transformer, in order to use as a regulating element

a transistor with a small maximum allowable reverse biasing of the base-emitter junction, the transformer is made with an additional winding, one of its terminals connected to the middle terminal of the primary winding, and the other through the junction of the anode - cathode of series-connected diodes - to the emitter of the control transistor.

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