SU754599A1 - Device for grid control converting unit power-diodes - Google Patents

Description

The invention relates to a converter technique and can be used as a pulse shaper applied to control circuits of valves assembled according to a three-phase bridge circuit.

Known devices for grid control, containing transformers 11] and [2].

The closest in technical essence to the present invention is a device containing two groups of magnetic amplifiers with a symmetric magnetic system operating in a three-phase two-wave amplification mode and used as a source of control voltage, the load windings of the amplifiers are connected to two unified counter-directed primary windings of peaks transformers [2].

The disadvantages of this device are large dimensions, low speed resulting from a two-stage magnetic conversion of the control signal, and the complexity of the circuit.

The purpose of the invention is to reduce the weight and dimensions.

2

This goal is achieved by the fact that the source is connected between the zero points of the stars of the primary windings of peak transformers.

FIG. 1 is a schematic diagram of a device _5; on

FIG. 2 is a variant of its implementation.

The circuit contains six peak-transformers 1, 2, 3, 4, 5 and 6 (according to the number of valves in relation to the three-phase bridge circuit of A. N. Larionov).

Yu Each peak-transformer has an additional winding 7 control, designed for the rated current of the converter plant. The control windings 7 are connected in series between with ₁₅ combat and are also connected in series with the grounded pole of the power circuit.

The AC windings 8 of the peak transformers 1–6 are powered by a phase regulator (conventionally lowered) and are connected to two reverse stars, and a constant voltage from a stabilized source is supplied to zero points of which.

With this inclusion of a stabilized DC voltage flowing through the primary windings 8 peak-transformer3

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four

mator 1-6 direct current does not go out

winding circuit of phase regulator.

The normal operation of the circuit assumes counter-switching of the windings 7 and 8 on each core of the peak-transformers, and the magnetizing amp-turns created by the windings 7 work on locking, and those created by the windings 8 - on unlocking the power valves.

The circuit is configured so that when the rated operating current flows through the control windings 7, the magnetizing magnetic flux is zero, and the valve ignition angle is uniquely determined by the magnitude and phase of the alternating magnetic flux in the core of each peak transformer.

When the rectifier current deviates from the nominal, the unbalance of the magnetizing magnetic flux occurs, as a result of which the phase of the firing pulse shifts in the direction opposite to the disturbing effect, which leads to the restoration of the nominal current value.

The proposed device can be made to control the converter plant with the number of valves that are a multiple of six.

In the diagram of FIG. 2 each of the groups of primary windings of alternating current peak-transformers (peak-chokes), assembled in reverse stars, is made of two parallel-connected star chains with individually derived zero points, between the corresponding pairs of which are switched on by a DC source, creating counter-directed magnetic fluxes in the cores of peak-transformers (peak-chokes).

The circuit contains peak transformers 1, 2, 3, 4, 5, and 6, each having two primary windings 7 and 8 of alternating current, which are connected in parallel and are assembled in the drawing of a star with individually drawn zero points. Moreover, the stars from the windings 7 and 8 of the peak transformers 1, 2 and 3 are included opposite to the stars from the windings 8 and 7 of the peak transformers 4, 5 and 6.

Between the zero points of the windings of 7 pictransformers, voltage is applied and ₍ , and between zero points of windings 8, voltage and 2. On the side of the AC terminals, windings 7 and 8 are powered from a phase shifter conventionally omitted in the drawing.

The device shown in the diagram works both in a three-phase bridge and in a six-phase simple rectification circuit.

The device works as follows.

With steady-state nominal parameters in the converter circuit (current, voltage and ignition angles in the grid circuits of the valves), the voltage of the reference source Π (chosen such that the bias current flowing in the windings 7 creates ampere turns equal to the amperes generated by the current flowing on the windings 8 under the action of voltage and g negative current feedback (current stabilizer) or voltage (voltage regulator) of the converter.This voltage or current is taken from the alternating current side of the converter and in Straightened by a bridge from the valves.

Due to the fact that the saturation of the cores of peak transformers usually occurs with ampere turns, significantly lower effective ampere turns, the current flowing through the windings 7 and 8 only distorts the sinusoidal alternating current without changing its area during the period of current change.

Consequently, the splitting of the primary windings of peak transformers into two is done without increasing the consumption of copper.

When the current (voltage regulator) or voltage (voltage regulator) of the converter deviates from the nominal, an unbalance of the ampere-turns of the bias on the peak-transformers arises, which, by shifting the ignition pulse in phase, leads to the restoration of the nominal current (voltage) of the converter.

The device can be performed on a number of phases, a multiple of three for bridge and a multiple of six for simple converter circuits.

The proposed device differs from the known high-speed and reduced mass-dimensional indicators.

Claims (1)

Claim A device for grid control of the ventilators of a converter plant assembled on a three-phase bridge circuit containing peak transformers, the primary windings of which are assembled into two reverse stars, and a source of constant stabilized voltage, characterized in that, in order to reduce the mass-dimensional indices, the specified source included between the zero points of the stars of the primary windings of peak-transformers.