SU1436225A1 - D.c. to d.c. voltage thyristor converter - Google Patents

Abstract

The invention relates to a converter technique. The purpose of the invention is to increase the stability of the converter while at the same time expanding the range of output voltage regulation. The device contains a bridge on thyristors 1-4 and diodes 5-8 of a counter current. The diagonal of the AC bridge is connected in parallel with the commutation, and the oscillating circuit and the primary winding of the transistor 13 are connected. The secondary winding of the transistor 13 via the rectifier 14 and the smoothing filter 15, starting from the throttles, is connected to the load circuit 16. The parallel-connected additional thyristors 11, 12 are connected in series with the switching oscillating circuit and are unlocked by the control unit at the beginning of each half-cycle of the inverted voltage to pass three half-waves of the oscillating circuit current . 1 il. from the next

Description

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The invention relates to devices for converting a constant electric voltage to a constant with a high frequency link and can be applied to rectifying devices with a transformerless input.

The purpose of the invention is to increase the stability of the converter while at the same time increasing the range of output voltage regulation.

The drawing shows the electrical circuit of the converter.

The converter contains main thyristors 1-4, connected in a bridge circuit, diodes 5-8 of countercurrent, connected anti-parallel to the thyristors, a series oscillatory circuit, w, of the chokes 9 and the capacitor 10. The series oscillator circuit is connected to the diagonal of the alternating circuit. the current of the bridge circuit through the additional thyristors 11 and 12 connected in parallel to the AC diagonal of the bridge circuit is also connected to the primary winding of the transformer 13, and its secondary winding through rectifier 14 and burned - the living filter 15, starting from inductance, is connected to the load circuit 16. The control unit includes a current transformer 17, a comparator 18, a one-shot 19, a logic element AND 20, a pulse former 21, a master frequency generator 22, a pulse distributor 23, drivers 24- 27 pulses controlling the main thyristors.

The Converter operates as follows.

When pulses are received from the master oscillator 22 of the control unit through the distributor 23 and the formers 24-27, the main thyristors of the two main thyristors of the opposite shoulders of the bridge, for example 1 and 4, are unlocked and a voltage equal to the voltage of the source connected to the primary winding of the transformer 13 is applied to the diagonal of the direct current bridge circuit. At the same time, pulses are triggered from the driver oscillator 22 through the pulse shaper 21, which enable one of the thyristors 11 or 12, and a current arises in the oscillatory circuit with the choke 9 and the capacitor 10. At the same time, a signal is applied from the master oscillator 22 to the input of the single-vibrator 19. The pulse duration at the output of the one-shot 19 is somewhat longer than the duration of two half-periods of current oscillation in the oscillatory circuit.

At. When the current in the oscillating circuit passes through zero, a voltage pulse is generated at the output of the comparator 18 connected to the secondary winding of the current transformer 17 and is fed to the input of the element. And 20. In the presence of the output voltage of the one-shot 19 and the pulse from the comparator 18, a pulse arises at the output of the element 20 and opens the locked thyristor 11 or 12 and the oscillator through the driver 21. a new process continues. Starting from the moment when the instantaneous current of the oscillatory circuit in the second half-wave becomes greater than the current of the transformer primary winding, the current from the open thyristors 1 and 4 goes to the reverse

0 diodes 5-8. In this case, thyristors 1 and 4 will close and reverse voltage will be applied to them.

After passing through the amplitude of the current of the oscillatory circuit at the point in time when the current of the oscillatory circuit in the second half-wave again compares with the current of the primary winding of the transformer 13, the reverse diodes are locked. The flow of current in the oscillatory circuit continues along the circuit through the primary winding of the transformer 13, which then enters the short circuit mode, since with the current line in the load 16 connected to the secondary winding of the transformer, all the diodes of the rectifier 14 are unlocked by nor emf self-inducting smoothing

5 of the filter 15. When the current of the oscillating circuit passes through zero to the third half-wave, a pulse appears again at the output of the comparator 18, and since the voltage of the one-shot 19 also has a voltage, a pulse occurs at the output

0 of the element AND 20, which through the driver 21 unlocks the closed thyristor 11 or 12. The oscillation of the current in the oscillatory circuit continues. After the third half-wave of the oscillating circuit's output current, the single-oscillator pulse 19 will be absent, the passage of current through zero at the end of the third half-wave will not cause the appearance of a pulse at the output of the element 20 and both of the thyristors 11 and 12 will remain closed. All the thyristors of the converter are closed until the next pulse from the master oscillator 22 opens, at which another pair of main thyristors 2 and 3 will open and the processes in the converter will continue in the next half-period inverted to the voltage similarly considered.

Due to the fact that the current oscillations are limited to three half-periods in the oscillatory circuit during each half-period of the inverted voltage, the stable operation of the proposed converter is maintained over a large range; not reducing the frequency of the master oscillator in comparison with the nominal one, which allows for deep regulation of the voltage level at the output of the driver. At the same time, the converter does not lose stability with large changes in the load parameters, and the external characteristic of the converter is rigid.

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Claims (1)

DETAILED DESCRIPTION OF THE INVENTION Thyristor DC to DC converter containing a bridge inverter on thyristors shunted by opposing diodes, a thyristor control unit, the diagonal of the DC bridge connected to the terminals of a DC voltage source, and the AC diagonal is connected in parallel a switching oscillating serial circuit and the primary winding of a transformer, the secondary winding of which is connected to a rectifier connected to a smoothing choke filter connected to the load circuit, characterized in that, in order to increase the stability of the converter while increasing the output voltage control range, additional thyristors connected in parallel with the switching oscillator circuit are introduced into it, and the control unit is designed to provide unlocking additional thyristors at the beginning of each half-cycle of the inverted voltage to pass three half-waves of the oscillating circuit current.