SU1374366A1 - Two-cycle d.c. voltage transistor converter with current feedback - Google Patents

Abstract

This invention relates to the field of electrical engineering. The goal is to increase efficiency. The circuit provides a stabilized voltage at the output. As the output voltage rises, the voltage at the input of the threshold element 9 increases, the output voltage of which is applied to the secondary winding 3 of transformer 1 and blocks the diodes 7 and 8, and hence the transistors 5 and 6. During the pause, the capacitor 11 is discharged through the load and the output voltage starts to decrease. 2 Il. i (L

Description

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The invention relates to electrical engineering and can be used in secondary power supply systems for converting a level and stabilizing a constant voltage.

The purpose of the invention is a higher efficiency.

Figure 1 is a schematic diagram of the proposed converter; FIG. 2 shows an example of a circuit of a relay threshold element.

The Converter (figure 1) contains the output transformer 1 with the primary

2 and secondary 3 windings. The midpoint of the primary winding 2 is connected via the power source 4 to the emitters of the power transistors 5 and 6, the collectors of which are connected to the outermost leads of this winding. The bases of transistors 5 and 6 through the main diodes 7 and

8 are connected to the outermost leads of the secondary winding 3 of the output transformer 1. At the output of the converter, a relay threshold element 9, a resistive voltage divider 10, a capacitor 11 and a load 12 are connected. The input of the relay threshold element

9cv is connected to the midpoint of the resistive voltage divider 10, and its output through diode 13 is connected to one of the extreme ends of the secondary winding

3 output transformer 1. A starting resistor 14 is connected between the ends of the secondary 3 and primary 2 windings of the transformer 1.

The circuit works as follows: When the transistor 5 is open, the power supply source 4 is applied to half of the primary winding 2 of transformer 1. Under the influence of the voltage of power supply 4, magnetization reversal of transformer magnetic circuit 1 occurs. At the moment of magnetic conductor increase, its magnetizing current increases, and and the collector current of transistor 5, Transistor 5 goes out of saturation, the voltage across it increases, and the voltage across half of the winding 2 decreases and changes sign. Next, the processes in the circuit are repeated. The voltage is stabilized as follows. When the voltage at the output of the converter increases, the voltage at the input of the relay threshold element 9 increases, and when it reaches the threshold of unlocking, the output voltage of the element 9 becomes approximately equal to the output voltage of the converter. This voltage-through diode 13 is applied to the secondary winding 3 of transformer 1 and closes the diodes 7 and 8 and transistors 5 and 6. The DC / DC converter stops working. During a pause, the capacitor 11 is discharged through the load 12 and the output voltage starts to decrease; which leads to a decrease in the voltage HS of the input of the relay threshold element 9. When this voltage reaches the threshold of locking the relay threshold element 9, it returns to its original state and the voltage at its output becomes close to zero. In this case, the current of power supply 4 flows through half of the winding 2, resistor 14, diode 8, the emitter-to-base junction of transistor 6, and it opens, which triggers the voltage converter to start. Capacitor 11 is charged and the output voltage starts to increase. Further, the processes in the circuit are repeated.

The circuit of the relay threshold element (FIG. 2) can be performed, for example, on an operational amplifier.

and contains an operational amplifier 15, covered by a positive feedback resistor 16, a reference voltage circuit on Zener diode 17 and a resistor 18 connected to the output

converter The output of the operational amplifier 15 is connected to the cathode of the diode 13, the anode of which through the diode 8 is connected to the base-emitter junction of the transistor 6.

As the output voltage of the converter increases, the negative potential at the non-inverting input of the op amp increases. As soon as this is negative

the potential will exceed the potential at the inverting input of the operational amplifier 15, which is defined by a chain consisting of the resistor 18 and the stabilizer 17, the voltage at the output of the operational amplifier 15 due to the positive feedback through the resistor 16 quickly becomes negative and turns off converter. When reducing the output level

the voltage of the converter to the value determined by the resistive divider 10 and the feedback resistor 16, which creates the necessary hysteresis of the circuit, the operational amplifier 15 is clear

the switch is turned on, the potential of its output becomes close to zero, the diode 13 is closed and the converter starts to work. Further, the processes in the circuit are repeated. Pulse mode allows to increase the efficiency of the converter.

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formula of invention

A push-pull transistor converter of direct voltage with a current feedback, containing an output transformer, the middle terminal of which is connected to the first input and first output terminals of the converter, and the extreme leads of this winding are connected via power transistors with the second input terminal. converter

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-f, the secondary winding of the output transformer is connected by extreme leads through the main diodes to the tales of the power transistors, and by the middle output to the second output terminal of the converter, characterized in that, in order to increase the efficiency, a relay threshold element and an additional diode are inserted, and the relay input the threshold element is connected to the output terminals of the converter, and the output of the relay threshold element is connected via an additional diode to one of the extreme terminals of the secondary winding of the output transformer, moreover, the relay threshold element is implemented on the operational amplifier.

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Claims (1)

Claim A push-pull transistor DC-DC converter with current feedback, containing an output transformer, the middle terminal of the primary winding of which is connected to the first input and first output terminals of the converter, and the extreme terminals of this winding are connected through power transistors c. the second input terminal of the converter, and the secondary winding of the output transformer is connected by the extreme terminals through the main diodes to the base transistors of the power transformers, and the middle terminal is connected to the second output terminal of the converter, characterized in that, in order to increase the efficiency, a relay threshold element 10 and an additional diode are introduced moreover, the input of the relay threshold element is connected to the output terminals of the converter, and the output of the relay threshold element through an additional diode is connected to one of the extreme terminals again th winding of the output transformer, and the relay threshold element is made on an operational amplifier.