SU1125716A1 - Adjustable three-phase a.c. voltage-to-a.c. voltage converter - Google Patents

Abstract

ADJUSTABLE THREE-PHASE ALTERNATING VOLTAGE TO AC VOLTAGE CONVERTER containing a three-phase booster transformer; the primary windings of each phase of which is connected via a switching unit with i terminals to be connected, the voltage of the corresponding phase, and the secondary winding of each phase is connected between the input and output terminals of the corresponding phase, so that that, in order to improve the shape of the output voltage, injected into the phase of a three-phase transformer; Two additional windings are given, while the additional winding of the other two 5 phases is included counter-sequentially with the secondary winding of each phase

Description

one . The invention relates to the field of electrical engineering and can be used to regulate, in particular, to stabilize alternating voltage of three-phase electrical consumers. Three-phase transformer and thyristor alternating voltage regulators are known that contain a transformer with secondary windings, which are connected to zero point using two thyristor switches, each of the thyristors of one switch is switched on at the beginning of the corresponding half-phase phase voltage, changing the switching angle The resistors of the other switch with respect to the first switch control the output voltage ij. The disadvantages of such devices are the difficulty of obtaining high control accuracy, especially in asymmetrical modes of operation, and the distorted output voltage form. The closest to the invention of the YaV is an adjustable three-phase AC-to-AC converter containing a three-phase voltage boost transformer, the primary windings of each phase through which the switching unit is connected to the terminals for connecting the voltage of the corresponding phase, and the secondary winding of each phase is connected between the input output terminals of the respective phase 2. A disadvantage of the known device is a significant distortion of the shape of the output voltage when deep adjustment is necessary. The aim of the invention is to improve the shape of the output voltage. This goal is achieved by the fact that an adjustable three-phase AC-to-AC converter contains a three-phase booster transformer, the primary windings of each phase of which are connected to the terminals for connecting the voltage of the corresponding phase through the switching unit, and the secondary winding of each phase is connected between the input and output the conclusions of the corresponding phase, two additional windings are introduced into each phase of the three-phase transformer, with the opposite side of the secondary winding zhdoy phase included an additional winding of the other two phases. 162 Three-phase booster transformer can be designed as a group of three single-phase transformers. Fig. 1 is a schematic diagram of a device with a two-way voltage regulation in Fig. 2, the same with a one-way voltage regulation. The device of FIG. 1 contains a three-phase power booster transformer consisting of three single-phase booster transformers 1-3, in each of which the primary windings 4-5 are made with a different number of turns and are connected counter-sequentially. One of the free conclusions of the winding 4 (the end of the winding) and the general conclusions of the primary windings 4-5 (the beginning of the windings) through the thyristor keys on the opposite-parallel thyristors 6-7 and B-E, which form the switching unit, are respectively connected to one of the input or output - device connections. Another free terminal of the winding 5 is connected to another input or output terminal of the device (in this example, to the zero terminal). Counter-connected secondary winding 10 of each phase and additional windings 11 and 12 of the other two phases are connected between the respective input and output terminals of the device. All thyristor switches are connected to control unit 13. The device of figure 1 works as follows. When operating under load, at the beginning of each half-period of the input voltage, a thyristor 8 or 9 is switched on (in the corresponding half-period). Turning on the thyristors 8-9 provides the connection of the winding 5 to the input terminals. In this case, the secondary winding 10, which is switched on oppositely with the mains voltage, provides the voltage to the device with the output voltage of the device less than the network voltage. With a time shift from block 13, a thyristor 6 or 7 is turned on (in the corresponding half period), the angle of the leading edge of the control pulses is determined by block 13 of control. When the thyristor 6 or 7 is opened, the windings 4-5 oppositely connected are turned on, their joint action, with a larger number of turns at the winding 4, ensures a change in mode for the voltage boost. The voltage of the winding 4 is applied to the open thyristor 8 or 9- and closes it. Thus, the output voltage Lazy M (d is formed by the geometrical composition of the input voltage IL, the additional voltage of the winding of the same 10 oct1 ilg / o additional voltage of the additional windings I, and 12 of the other two phases DC, and (J, Jpegyling its effective value is provided by changing the turn-on angle of the vTopOB 6-7 tiris control unit 13. The device of FIG. 2 contains a three-phase power-voltage boost transformer consisting of three single-phase transformers 1-3, in each of which the primary winding A tiris The key switch on counter-parallel thyristors 6–7 is connected by one output (start) to one of the input or output pins, and the second output to another input or output terminal and is bridged by a key on counter-parallel thyristors 8–9. the connected secondary winding 10 of each phase and the additional windings 11 and 12 of the other two phases are connected between the respective input and output terminals.All the thyristor switches are connected to the control unit 13. The three-phase AC voltage regulator of FIG. 2 operates as follows. 64 When operating under load, at the beginning of each half-period of the input voltage, thyristor 6 or 9 is turned on and shunts the primary winding 4, while the output voltage is approximately equal to the input voltage and the voltage on the winding 10 is close to zero. With a time shift from the control unit 13, the thyristor 6 or 7 is turned on (in the corresponding period), the shift angle of the leading edges of the control pulses is determined by the control unit 13. . When opening the thyristor 6 or 7, the primary winding 4 connects to the input ledges, which leads to a change in the polarity of the voltage on this winding and provides the operating mode of the transformer on the voltage boost. The voltage of the winding 4 is applied to the thyristor 8 or 9 and shorted to it. Geometric summation: stresses in this device, shape; The output voltage and the regulation method are the same as in the device of FIG. Due to the presence of additional windings of the other two phases in the secondary winding circuit, in the half-cycle curve of the output voltage three jumps are created, providing voltage regulation, the magnitude of these jumps. less than the magnitude of one. jump in the absence of additional windings, which brings the shape of the curve to the sinusoid.

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Claims (1)

ADJUSTABLE THREE PHASE VOLTAGE CONVERTER- ’ NII IN VARIABLE, containing a three-phase booster transformer: ^ the primary windings of each phase of which are connected through a switching unit; with terminals for connecting the voltage of the corresponding phase, and the secondary winding of each phase is connected between the input and output terminals of the corresponding phase, characterized in that, in order to improve the shape of the output voltage, two additional windings are introduced into each phase of the three-phase transformer, opposite this with the secondary winding of each phase, an additional winding of the other two phases is included *>