SU150548A1 - Controlled rectifier device - Google Patents

Description

With deep regulation of controlled rectifier devices, they are significantly degraded. and the power factor of the converter plant, the latter being proportional to the degree of reduction of the rectified voltage.

To improve. The power factor of such devices, for example, three-phase, proposes an opposite to valve B each phase circuit to include an additional uncontrolled single-pole rectifier and parallel to the indicated valve to connect a choke in each phase and a source of control voltage having a common point with the load.

FIG. 1 shows a schematic diagram of the proposed single-phase rectifier device; on fi.g. 2 — corresponding curves of currents and voltages; in fig. 3-circuit diagram of a three-phase rectifier device; in fig. 4-current curves and voltages corresponding to this last scheme.

Two currents can simultaneously flow through the controlled valve B (Fig. 1) —the current i from the low voltage source (/ i DC and in the nonconductive direction — opposite to the direct current — the current l from single-phase half-wave recirculation in the conducting direction) A motor consisting of a high voltage AC voltage source 11 and a rectifier B, which is connected to the gate B via the RH payload. If the control DC voltage is zero, then the current through the payload RH practically does not leak, because neutral B in the non-conductive direction it cannot pass, and in a control voltage-direct current circuit the half-wave current is limited by the inductance of the throttle L to a very small value.

If we now increase the control voltage L / i of the direct current, then through the Si valve in the conducting direction will begin

No. 150548-2

the current ii flows, and simultaneously to meet this current, during the period of the positive half-wave of a single-phase rectifier, current / g pulses flow through the load n and cause the appearance of the rectified voltage UH- Current pulses rh, rise to the current ii, reduce the current of the Bi valve to zero, as a result of which this current also has the form of pulses 1b, shown in FIG. 2

By varying the control voltage t / i from zero to the limit value, it is possible to vary within these limits the amplitude of the current current iz pulses and, consequently, the magnitude of the voltage UH on the load, and this value is ten or hundreds of times larger than the control voltage. The resulting control power is as much less than the power at the payload, and from this point of view, the proposed device can be considered as a powerful voltage amplifier with a very large amplification factor.

FIG. Figure 2 shows the curves of a single-phase rectifier current, from which it follows that the control diode acts as a current limiter, O1C1; to the upper part of the current wave of a single-phase rectifier.

The control voltage L / i, which provides the maximum voltage across the load, must be equal to the sum of the direct drop in the valve and the voltage drop in the active resistance of the throttle when the rated current flows through the valve Bi. The maximum load voltage Unna corresponding to this current is determined by the amplitude of the voltage U, which should not exceed the maximum reverse voltage of the Bi valve.

In modern il clad semiconductor diodes for rectifying alternating current, the ratio of the direct drop and amplitude of the reverse voltage reaches 200 to f 1200. This ratio characterizes the limiting ratio of the controlled voltage UH to the controlled voltage Ui, and if the controlled valve considered as a dc amplifier, it determines its limiting gain achieved in a single stage.

As shown in FIG. 2, the load on the device without the use of filters has the form of pulses. In order to obtain a constant voltage U -cp, it is necessary to use multi-phase rectifying devices.

FIG. 3 is a diagram of a three-phase rectifying device composed of three single-phase Bl valves, and

, each of which conducts one third of the current - and acts like a single-phase rectifier. Uncontrolled rectifiers B2, AND And the corresponding inductors Li, LZ and La are included in the corresponding phases.

FIG. The 3 split lines show the transformer power supply of unmanaged rectifiers, the dotted lines of the hybrid transformer power supply version of rectifiers.

FIG. 4 - - "V / Ji, 1f2," 03 and if, if, and if - designate the currents and voltages in rectifiers Br, and B of the corresponding phases.

The high value of the power factor of the proposed device over the entire control range is due to the fact that the voltage regulation occurs due to the cut-off of the upper part of the current wave of the rectifier without its mixing; Therefore, the shape of the current in each phase