SU1050071A1 - Single-phase resonant inverter - Google Patents

Abstract

A SINGLE-PHASE RESONANT INVERTER containing a bridge cell connected to the INPUT through a filter choke on thyristors and diodes with a serial commutator LC-KOHjypOM in the diagonal of an alternating current, as well as a separation capacitor and a load that is different in order to improve the quality of the output current by improving its sinusoidality, it is equipped with three additional coupling capacitors, and the bridge cell is made according to the circuit with cut-off diodes, with the load being connected between the middle points Ai two chains of separation capacitors connected in parallel according to the connected bridge thyristors.

Description

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The invention relates to electrical engineering, in particular, to converter technology, and can be used to develop direct current energy converters to high frequency alternating current energy.

Converters made according to various voltage inverter circuits are known - parallel inverters, series inverters, high-frequency switching inverters, pulse-switching inverters, etc. To obtain an increased conversion frequency, series resonant inverters are widely used, in which, by using a series resonant circuit, the current of the controlled valve during the entire conduction interval varies in time according to the oscillatory law.

The most important advantages of resonant inverters that make them promising to use at higher frequencies are the relatively low anode current rise rate in controllable gates and the possibility of obtaining large, lockable time for controllable gates by extending pauses between the start-up and control pulses 1.

Closest to the invention is a resonant inverter, which contains a thyristor bridge with reverse diodes and a switching LC circuit in the diagonal connected to the input terminals through a filter choke, as well as a series-connected load and separation capacitor.

This circuit allows one to obtain an alternating current of increased frequency at relatively low rates of growth of the anode current in controllable gates, and operation at changing the load over a wide range from idle to co. short circuit, small dependence of the angle of locking and voltage on thyristors on the load resistance 2.

A disadvantage of the known inverter is the low quality of the output current, in that the current waveform in the load is very different from sinusoidal.

The aim of the invention is to improve the quality of the output current by improving its sinusoidality.

Set goal Achieved by the fact that three additional LC capacitors are inserted into the AC diagonal of the thyristors and diodes with a series commutating LC circuit through a filter choke in a single-phase resonant inverter that contains a bridge cell on the thyristors and diodes connected to the input pins. , and pavement cell completed

A circuit with cut-off diodes, with the load connected between the middle points of two chains of times / Selective capacitors connected in parallel according to the connected bridge thyristors.

At the same time, there are identical flow paths through the load of positive and negative half-waves of the current, which significantly affects the improvement of the quality of its shape.

FIG. 1 shows a single-phase resonant inverter circuit; in fig. 2 - current waveform and in single-phase resonant inverter load.

A single-phase resonant inverter is powered from a DC power source through the filter choke 1. The inventory is made according to a bridge circuit and contains thyristors 2-5, diodes 6-9, LC circuit 10 of artificial switching (in the form of series-connected switching capacitor 11 and drossel 12), included in the diagonal of the alternating current bridge 2-5, load 13, connected between the middle points of the two circuits of the split capacitors (14, 15 and 16, 17) connected in parallel according to the bridge thyristors (2, 3 and 4, 5, respectively) and through diodes 6 , 7 and 8, 9 respectively directly connected to the diagonal of the direct current of the bridge.

The device works as follows.

When connected to a power source, the separation capacitors 14, 15 and 16, 17 are charged through filter choke 1 and diodes 6, 7 and 8 9, respectively. When opening a pair of thyristors 2- and 5 of the bridge, the separation capacitors 14 and 17 are discharged. In this case, a negative half-wave of a sinusoidal current is formed in the load. To obtain a positive half-wave of a sinusoidal current, thyristors 3 and 4 are opened for discharging capacitors 15 and 16, respectively. The device differs favorably from the fact that the current form in the load is much closer to the sinusoidal shape (Fig. 2).

The quality of the output current can be assessed using the distortion factor Kp, which is equal to

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Ki iKfii

where 1st (,) is the effective value of the first

load current harmonics; 1n is the effective value of the load current.

The closer Kp .. to the unit, the closer the shape of the current in the load to the sinusoidal. For the current curve (Fig. 2) Cc 0.95, for the prototype Cn 0.9.

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Claims (1)

SINGLE-PHASE RESONANT INVERTER, comprising a bridge cell connected to the input terminals through a filter inductor on thyristors and diodes with a series switching LC circuit in the diagonal of the alternating current, as well as a isolation capacitor and load, characterized in that, in order to improve the quality of the output current by improving its sinusoidality, it is equipped with three additional isolation capacitors, and the bridge cell is made according to the scheme with cut-off diodes, and the load is included between the midpoints two circuits of isolation capacitors connected in parallel according to the connected thyristors of the bridge. SU „„ 1050071/3 Ό Figure 1