SU832677A1 - Ac-to-dc voltage converter - Google Patents

Description

(54) AC VOLTAGE CONVERTER TO PERMANENT

When applying to the thyristor bridges 10-12, control pulses through the load (not shown) starts to pass a direct current 1a (Fig. 2a). Smoothing it is provided by droplets 13-15, installed in the circuit of the primary phase windings 2 of transformer 1.

By passing the current of each phase of the primary winding 2 of the transformer through individual thyristor bridges 10–12 and regulator chokes 13–15, it is separated by phase-by-phase smoothing (Fig. 2a). At. This in the circuits of the primary winding of the transformer 1 passes through phase rectangular currents with a duration of 180 e. hail., shifted in phase by 120 al. (Fig. 26). These currents, when transformed to the secondary winding 2, create a three-phase secondary voltage of the appropriate shape. Diodes provide the rectification of the secondary current (its positive and negative phase rectangular current pulses) to direct current.

Due to the individual smoothing of the phase currents of the transformer, the secondary voltage leveling takes place and conditions are created for the parallel parallel straightening of the phase secondary currents, as a result of which three diodes are simultaneously held at any time, the duration of the conductive state of each diode is 180 el. hail, and the current is 1/3.

Since each four-shoulder bridge of the regulator is connected to the circuit of one of the phase primary windings, the duration of the conductor state of the thyristors of the regulator is increased from 60 (for the known) to 180 e. hail., which allows to increase the thyristor utilization ratio by:

ku by 15-25%, and accordingly, reduce the installed capacity of the thyristors.

Some complication of the converter due to the need to use three magnetically connected chokes is fully compensated by a simpler version of the transformer without booster-voltage primary windings that increase the rated power of the transformer.

In addition, large primary currents of the order of hundreds of amps are used for parallel connection of winding wires. Therefore, the implementation of three single-wire choke windings on a common magnetic core instead of one three-wire winding does not present a technical difficulty and, on the contrary, even leads to an additional increase in the reliability of the converter — the limiting of emergency currents is provided by a large inductance phase choke.

The additionally increased limiting of emergency currents, when electrochemically processing at small gaps, prevents frequent short circuits of the tool electrode with a part, resulting in high emergency currents to a rapid failure of an expensive tool.

Claims (2)

Invention Formula AC to DC converter containing a three-phase transformer with two groups of secondary windings connected in a "star, common points of which are connected and connected to the first output terminal, and the free ends through the valves are connected to the second output terminal, while the primary windings of the transformer are connected with input terminals and through controlled rectifiers with a choke, characterized in that, in order to reduce the installed power of the equipment, the primary windings of the transformer together with the single-phase controlled rectifier bridges connected in series in each phase are connected in a triangle, and the diagonal DC current of each one the bridge is covered with a winding of a three-winding choke. Information sources, taken into account in the examination 1. PP Beskov et al. Electrical equipment of machines for electrochemical processing. M., “Mechanical Engineering, 1977., p. 25-45. 2. USSR author's certificate in application number 2577559/07, cl. H 02 M 7/12, 1978. ffId, CL / 2Л  2a four -3a 2S 7 Have / 2 jtTvyvxj i U I C & d / e / Id W I / 5 I-4 J t five L7 1-8t i9 % Id 0us.2