SU1739455A1 - Secondary electric power supply source - Google Patents

Abstract

Usage: power supply of electronic devices of automation, telemechanics and communication. SUMMARY OF THE INVENTION: The control transistor turns on smoothly with some delay, depending on the time constant of the transistor filter circuit and the nominal resistance of the starting resistor. In this case, the voltage from the secondary side of the transformer is used to control the regulating transistor. A decrease in the voltage switched on the control transistor predetermines an increase in the reliability of this source, 1 Il.

Description

The invention relates to the field of electrical engineering and can be used to power various automation devices, telemechanics, and other electronic devices.

Known source of power,

A disadvantage of the known device is the low reliability due to the operation of the filter capacitors in the limiting modes at the moment of turning on the power.

The closest to the claimed technical entity is a power supply containing a transformer, a rectifying bridge, a regulating transistor and an output rectifier with a filter, in which a smooth increase in the output voltage occurs due to the shunting of the emitter-base junction of the resistor-capacitive transistor chained

A disadvantage of the known power source is low reliability due to the operation of transistors in limiting modes at the moment of switching on.

The aim of the invention is to increase reliability in operation.

This goal is achieved by the fact that a power source containing a transformer, the primary winding of which is connected to the leads for connecting the primary power source via an AC switch consisting of a diode bridge and a switching transistor in the control diagonal, is a power rectifier whose input is connected to the main secondary winding of the transformer, a smoothing filter, the output of which is connected to the output of the power rectifier, and the output circuit with terminals for connecting the load, RC node timing ki is included in the circuit between the output voltage driving the auxiliary rectifier circuit and the base of the switching transistor, inserted starting resistor connected

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between the power terminals of the key, and the transformer is provided with an additional secondary winding connected to the input of the auxiliary rectifier.

The drawing shows a block diagram of a power source.

The power supply contains a transformer 1, the primary winding of which is connected to the network through a starting resistor 2, a power rectifier 3 connected to one of the secondary windings of the transformer, a smoothing filter 4, an auxiliary rectifier 5 whose output is connected to the node 6 time delay, a diode bridge 7, connected in parallel to the starting resistor 2 and the switching transistor 8.

The secondary power source operates as follows.

When the power is turned on, the magnitude of the alternating voltage on the secondary windings of the transformer and the maximum pulse current across the primary winding of the transformer are determined by the nominal resistance of resistor 2, while the switching transistor 8 is closed. The magnitude of the alternating voltage supplied to the auxiliary rectifier 5 from the transformer secondary winding should be sufficient to open the switching transistor 8. A smooth switching on of the switching transistor starts with a certain delay, which is determined by the voltage of the base-emitter of the switching transistor 8 and parameters node 6 time delay. During the delay time, the interturn capacitances of transformer 1, filter capacitors 4 are partially charged, and at the time of switching on the switching transistor, there is already a significant decrease in the voltage applied to the switching transistor 8, the value of which is determined by the starting resistor 2 and the delay time smooth switching on the switching transistor 8, which ensures its safer operation at the moment of smooth switching on. After opening the switching transistor, the voltage on the primary winding of the transformer gradually increases, which causes a smooth increase in the voltage on the secondary windings of the transformer, and this leads to an even greater opening of the switching transistor 8. Thus, the switching transistor 8 smoothly turns on to full saturation than a gradual increase in the output voltage at the output of the power rectifier 3, and hence a smooth charge of the capacitance of the filter 4, is ensured. Oski current through the filter capacitor at the moment of incorporation in the transformer network.

This invention makes it possible to significantly increase the reliability of the power supply, since during the delay time before the switching-on switching-on transistor is started, a significant reduction in the switching voltage by the switching-transistor already occurs. The decrease in the switching voltage during the delay time is due to the fact that the transformer is supplied through the starting resistor, and the interturn capacitances of the transformer and filter capacitors are significantly charged, and by the time the switching transistor is switched on, the voltage on its collector is already reduced.

Claims (1)

Claims of the invention A secondary power supply source comprising a transformer, the primary winding of which is connected to the leads for connecting the primary power source via an alternating current switch consisting of a diode bridge and a switching transistor in the control diagonal, a power rectifier whose input is connected to the primary secondary winding of the transformer , a smoothing filter, the input of which is connected to the output of the power rectifier, and the output circuit with terminals for connecting the load, the RC-node of the time delay, connected to the current supply circuit between the output of the auxiliary rectifier and the base circuit of the switching transistor, characterized in that, in order to increase reliability in operation, a starting resistor connected between the power terminals of the switch is inserted into it, and the transformer is provided with an additional secondary winding connected to input auxiliary rectifier.