SU1693698A1 - Three-phase-to-one-phase voltage converter - Google Patents

Abstract

The invention relates to converter technology and can be used in secondary power sources. The purpose of the invention is to reduce the low-frequency modulation factor of the output voltage. The device contains thyristors 1, included in a closed ring circuit, the odd nodes of which are connected to the input phases of the three-phase source 2 Even-numbered nodes are connected to the output terminal 4 through separation capacitors 3. The thyristors of the block 5 are connected according to the three-phase bridge diagonal of which is connected to the input terminals 2, and the diagonal of the direct current is shunted short and forms the second output terminal 4 The control unit 6 with phase-out outputs provides alternate switching of the thyristor groups, ano hydrochloric group of thyristors 5 and an odd group of thyristors 1 - from straight unit outputs 6; the cathode group of thyristors 5 and the even group of thyristors 1 from the direct outputs of block 6; the cathode group of thyristors 5 and the even group of thyristors 1 are from the inverse outputs of block 6. The high-frequency output voltage is modulated by a low-frequency component with a period equal to 1/6 of the network period. 2 Il. with s

Description

The invention relates to a converter technology, in particular to three-phase alternating current energy converters of industrial frequency to alternating current energy of increased frequency with a single-phase output.

The purpose of the invention is to improve the quality of the output voltage by degrading the low frequency modulation factor.

FIG. 1 shows a converter circuit; Fig 2 shows diagrams explaining his work.

The converter contains a block of 1 of six thyristors, which are connected in a unidirectional manner along a closed ring circuit, forming thyristors with odd and even

numbers when they are consecutively counted, one half of the points of connection of these thyristors are connected through one to the output pins of the 2 converters, a block of 3 of three separation capacitors, some plates of which are combined to form one output pin 4 of the converter, and the other plates of the connecting thyristors Additional unit 5, control unit 6 with direct and inverse outputs, which are connected with control inputs of odd and even thyristors, respectively. Additional block 5 consists of six thyristors connected according to the three-phase bridge scheme, the diagonal of the alternating current of which is connected to the input terminals 2

about

H) 00

about

4} 00

the converter, and the diagonal of the direct current is shunted short and forms the second output terminal 4 of the converter, the control inputs of the thyristors of the anodic and cathodic groups of the three-phase motor are connected respectively to the direct inverse outputs of the control unit 5.

FIG. 2 denotes: a - phase voltages at the input terminals 2; b and c are the control voltages of the direct and inverse outputs of the control unit 6, respectively; g is the voltage across the separation capacitor 3, g is the voltage at the output terminals 4 of the converter.

The Converter operates as follows.

For a real converter, taking into account the internal resistance of the input source of alternating voltage, the thyristor switching algorithm is as follows. Consider the processes at the maximum voltage interval Dab. When applying control pulses from the direct outputs of the control system to the odd group of thyristors of block 1 and the anode carcass of block 5, the current loop is turned on: the upper thyristor of block 1 - the upper capacitor - load - lower middle thyristor of the block 5. The oscillatory load mode ensures current flow to output in one direction - a positive half wave is formed, and the thyristors are closed due to the recharge of the separation capacitor. After a short pause, necessary for quenching the thyristors, control pulses from the inverse outputs to the even group (1) and the cathode group (5) are applied. The circuit is turned on: the left upper thyristor of the unit 5 - the load - the upper capacitor - the left upper thyristor of the unit 1. This forms a negative half-wave of the current in the load, and the separation capacitor is recharged in the opposite direction. Since the voltage across the capacitor is variable, the buildup occurs, which is accompanied by significant voltage amplitudes, especially when the quality of the circuit in which the current flows is high. As a result, the initial voltages of the capacitor 1 of the circuit are large and the operating mode of the thyristors is essentially determined. Taking into account the initial charge on the capacitor in the latter case of starting the thyristors (from the inverted outputs of the control unit) when the main considered circuit is turned on, an additional circuit is also possible (if the input source contains internal resistance): middle upper thyristor of the unit 5 - load - upper condensate left upper thyristor of the unit 1. The additional circuit helps the main circuit, since the direction of the current in the load coincides.

The considered processes are repeated for 1/6 of the period at Uab max. Then, for Uac max, for the next 1 / b part of the period, other thyristors are included to form circuits for a positive current half-wave in the load (triggering from direct control pulses): unit upper thyristor 1 - upper capacitor load - lower right thyristor unit 5, for negative half-waves in the load (starting from the inverted control outputs) left upper thyristor of block 5 - load - upper capacitor - left upper thyristor of block 1 (additional circuit is the same as the one considered).

The operation is similar in the areas of maximum voltages Ubc, Uba, Uca, Ucb with the difference that other relevant thyristors of the circuit are included according to the cyclic permutation law.

The output voltage of the high frequency is modulated by a low frequency component with a period equal to 1/6 of the period of the input voltage of the three-phase source Tc.

Claims (1)

Invention Formula A three-phase voltage converter into a single-phase voltage converter containing a block of six thyristors connected in a single-pointed manner in a closed ring circuit, forming thyristors with even and odd numbers with their sequential counting. One half of the connection points of these thyristors are connected through one to the input terminals of the converter, a block of three separation capacitors, some of the plates of which are combined and form one output terminal of the converter, and the other plates of which are connected to the other half of the points of connection of the thyristors, as well as the control unit with direct and inverted outputs, which are connected to control inputs of respectively odd and even thyristors, characterized in that, in order to improve the quality of the output voltage by decreasing the low-frequency modulation level, it is equipped with an additional block of six thyristors connected in a three-phase bridge circuit, the AC current leads of which are connected to the input terminals of the converter, and the DC outputs are interconnected and form the second output terminal of the converter, with the control inputs The thyristors of the anode and cathode myme and inverse outputs of the block at the right of the e - groups of the bridge are connected to the mentioned paths. CL G 8 M {I I I I I M I G | I I t I I I I I I I I I I I I I I I-t  &