SU1658328A1 - Dc voltage converter - Google Patents

Abstract

The invention relates to electrical engineering and can be used in secondary power supply systems. The purpose of the invention is to increase efficiency. The converter contains a half-bridge inverter on power transistors 1 and 2 and input capacitors 3 and 4. The output circuit of the inverter is turned on for output transformer 6. Resonant capacitor 7 with additional choke 8 form the first parallel circuit tuned to the first resonant frequency. The resonant choke 9 and the additional serial LC circuit 10 form a second parallel circuit tuned to a second resonant frequency exceeding the first resonant frequency. Due to this, the total input resistance of the circuit, through which the load is connected to the output of the inverter, is equal to infinity at both the first and the second resonant frequency. The operating switching frequency of the power transistors 1 and 2 lies between the first and second resonant frequencies and when it changes, stabilization (regulation) of the output voltage of the converter is ensured, in particular when the load changes. 2 Il. $ (L

Description

FIELD: electrical engineering. || can be used in secondary power systems.

The purpose of the invention is to increase efficiency.

FIG. 1 is a schematic diagram of a constant voltage converter; in fig. 2 - time diagrams that show his work.

The constant voltage converter (Fig. 1) consists of power transistors 1 and 2 and input capacitors 3 and 4, forming a half-bridge inverter connected to the input terminals 5 of the converter In the output circuit of the inverter connected in series the primary winding of the output transformer 6 and the parallel circuit, consisting of a resonant capacitor 7 and an additional throttle 8. To the secondary winding of the output transformer 6 through a parallel circuit, in one of the branches of which a resonant choke 9 is connected, and in another w - additional series circuit 10, connected to the rectifier 11 with a filtering capacitor and the load on the converter 12.

FIG. 2 shows time diagrams of voltages and currents:

t / Av is the voltage at the output of the half-bridge inverter;

/ e is the current of the primary winding of the transformer 6;

1/7 is the voltage across the capacitor 7; / 9 - current drossel 9; / s-current LC circuit 10;

ABOUT

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SO HCHE

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L / II - input voltage rectifier 11.

The converter of constant constant for 1 h (phi; 1) works as follows

The voltage of the primary power source applied to the input pins 5 of the converter is supplied to a capacitive voltage divider supporting half the supply voltage at the common connection point of the capacitors 3 and 4 of this divider. This voltage is also applied to transistors 1 and 2, switching out of phase with the switching frequency. The negative voltage front t / A (Fig. 2) at the time moment to recharges the pre-charged capacitor 7 through the transformer 6 (UT graph, Fig. 2). Formed by the elements of the oscillatory system 7-10, the current converter (Fig. 2) is the sum of the first and third harmonics. The first harmonic current is formed by voltage resonance, determined by the series connection of parallel circuit 7 and 8 and parallel circuit 9 and 10. The current of the first harmonic is formed mainly by the inductance of the throttle 9 and the capacitor 7 (Fig. 2 / e). The third current harmonic (Fig. 2, V) is formed mainly by the LC circuit 10, since the reactances of the circuits 7 and 8 and the reactive conductivity of the resonant droplets 9 in the voltage resonance region, which sets the third harmonic current, are small. At time t, the main capacitor 7 is fully recharged and the current / v drops to zero. In the time interval, the currents tend to infinity both at the resonance frequency of the circuit from elements 7 and 8, and at the higher resonance frequency of the contour from elements 9 and 10. The operating frequency of the converter is in the range between these resonant frequencies. The greater slope of the frequency response allows the range of allowable load variation to be expanded while the output voltage stabilizes at a given frequency rate.

Claims (1)

Invention Formula A constant-voltage converter containing a half-bridge inverter connected to the input pins, to the output diagonal of which the primary winding of the output transformer connected by the secondary winding is connected via a resonant capacitor to the rectifier input, whose output is shunted by the filter capacitor and connected to the output terminals of the converter, and an additional serial LC circuit, characterized in that, in order to increase the efficiency, the additional serial LC circuit in It is connected parallel to the resonant choke, and parallel to the resonant capacitor the introduced additional choke is switched on. and 1AS L L L I ° I I JI1ГЧ  V / M g