SU995233A1 - Three-phase series inverter - Google Patents

Description

- one

This invention relates to converters of direct current energy to high frequency alternating current energy.

The converters made according to various voltage inverter circuits are known - parallel inverters, series inverters, high-frequency switching inverters, pulse-switching inverters, etc., 1.

To obtain an increased conversion frequency, serial resonant inverters are widely used, in which, due to the use of a serial resonant circuit, the current of the controlled valve during the entire conduction interval varies in time according to the oscillatory law. Important advantages of sequential 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 long shutdown time of controllable gates due to elongation of pauses between the trigger, control pulses. To obtain a three-phase system of currents and voltages, as well as to obtain a large power in the load, three-phase series inverters 2 are used.

The disadvantage of three-phase serial inverter circuits is the poor quality of the output voltage (a significant difference from the sinusoidal form), as well as the limited scope.

Closest to the proposed

Claims (3)

10, by its technical nature, is a three-phase serial inverter, containing a three-phase valve bridge with three switching circuits and switching capacitors in a di-ac circuit, connected to the input terminals through filter chokes, and also contains separation capacitors in series and three-phase load. This scheme allows obtaining an alternating current of increased frequency at relatively low anode current rise rates in controllable gates, as well as the possibility of maintaining a sufficiently large locking angle of controllable gates when the load changes in a wide range JJ. A disadvantage of the known device is first of all the low quality of the output voltage (a significant difference from the sinusoidal form), which is caused by the following circumstances: when any of the pairs of controlled valves are operating, the current of charging of the switching capacitors flows through the corresponding phase loads in one direction only. The reason for this is the asymmetry of the inverter circuit relative to the load. In addition, the prototype device has a limited scope due to the fact that the load m. B. included only in the star with a zero wire. The purpose of the invention is to improve the shape of the output voltage curve. The goal is achieved by the fact that a three-phase serial inverter containing a three-phase thyristor bridge with switching capacitors in the diagonal of alternating current and three switching throttles connected in series with the corresponding branches of the bridge, connected to the input terminals via the corresponding filter chokes, as well as three separation the capacitor, some of the plates of which are connected to the connection points of the filter and switching inductors, and others - to a three-phase load, is equipped with three additionally dividing capacitors connected in series with the main dividing capacitors, each pair of said capacitor is connected parallel to the respective bridge branch. Due to the presence of additional coupling capacitors, the current recharging of the switching capacitors passes through the corresponding phase loads in both directions. Consequently, the quality of the output voltage, in particular, its sinusridality, is significantly improved. In addition, a three-phase load, connected to the diagonal of an alternating current of a three-phase bridge circuit of separation capacitors, can be connected according to any scheme (either a triangle or a star). This circumstance significantly clears the scope of the inverter. The drawing shows a three-phase serial inverter circuit. The three-phase serial inverter contains a three-phase valve matt 1 with three switching circuits 2-4 and switching capacitors 5-7, which are included in the diagonal alternating current of the bridge. The valve bridge is connected to the input terminals through filter chokes 8-13 and contains successively connected in the DC circuit separation capacitors 14-16 and three-phase load 17. The DC circuit includes additional separation capacitors 18-20 connected to the separation capacitors 14- 16 via a three-phase bridge circuit connected in parallel to a three-phase valve bridge, made on thyristors 21-26, to a diagonal of direct current. A three-phase load is connected to the diagonal of an alternating current of a three-phase bridge circuit of coupling capacitors. The device works as follows. When connected to a power source, a 14–16 splitter and additional 18–20 splitter capacitors are charged through filter chokes 8–13. Alternately, the thyristor pairs are opened in the following sequence: 21, 25; 21, 26; 22, 26; 22-24; 23, 24; 23, 25; 21, 25, etc. The switching capacitors 5–7 oscillate in the circuits containing switching chokes 2–4, dividing capacitors 14–16, load 17, and additional dividing capacitors 18–20. In the steady-state mode, the voltage on the switching capacitors 5-7 is alternating, periodic in time. In each phase of the load 17, only the alternating component of the current of the recharge of the switching capacitors 5-7 flows, the frequency of which is determined by the frequency of the thyristors 21-26. The voltage form on the load is alternating, close to sinusoidal. A three-phase serial inverter comprising a three-phase thyristor bridge with switching capacitors in an AC diagonal and three switching throttles connected in series with the corresponding branches of the bridge connected to the input terminals through the appropriate filter chokes, as well as three separation capacitors, one of which is connected to the points of connection of filter and switching chokes, and others to a three-phase load, characterized in that, in order to improve The shape of the output voltage curve is provided with three additional coupling capacitors connected in series with the main coupling capacitors, each pair of capacitors being connected in parallel to the corresponding branch of the bridge. Sources of information taken into account in the examination 1. Bedford B. et al. Theory of autonomous inverters, M., Energie, 1969. 2.Berkovich E.I. and others. Thyristor high frequency converters. L. “Energie, 1973. 3. USSR author's certificate number 558364, cl. H 02 M 7/515, 1974. 53 N} 10