CS257802B1 - Six-pulse thyristor direct frequency converter and voltage - Google Patents

Abstract

The circuit is designed to power three-phase motors in regulated electric drives with high demands on dynamics. In the known circuit of a direct frequency and voltage converter with dependent commutation of short-circuit thyristors, a pair of commutation transformers, six commutation chokes and six commutation capacitors were replaced by a single common series LC commutation circuit. This circuit fulfills its function by connecting between a node of a six-phase thyristor node rectifier and the opposite node of a six-phase diode node rectifier in which a series thyristor is connected, while the alternating sides of both rectifiers are connected to opposite poles of the direct sides of six three-phase diode bridges with an anti-parallel short-circuit thyristor. The continuity of the current in the load motor is ensured by a six-phase diode bridge shorted on the DC side by an anti-parallel zeroing thyristor, while the capacitor of the common commutation bipolar LC is also charged to the appropriate polarity through a pair of polarity reversal thyristors.

Description

257802 2

The invention relates to six-pulse four-phase direct frequency converters at napStieresp. triac frequency converters and power with their own common commutation.

A relatively simple direct frequency converter is known, consisting of two-phase phase transformers, each with three triple secondary windings. The transformer secondary windings are coupled, premultiplexed, and coupled to the beginning and end of the transformer, respectively. at the winding ends of the load motor, which is then coupled to the open triangle. Beginning of triplets of the three-phase transformer secondary windings are short-circuited sequentially with semiconductor knot switches consisting of a three-phase diode bridge and an anti-parallel short-circuit thyristor on one-way. The inverter also has two specially wound single-phase commutating transformers with three windings. Each commutating transformer transmits a tripping pulse from the commutation capacitor, which at the moment of switching on the short-circuit thyristor, connects to one of the other shorting thyristors, thereby providing dependent commutation of the short-circuit thyristors. the shorting thyristor that has just been turned off.

The main disadvantage of the known known simple direct frequency converter is the fact that the commutation capacitors are charged up to 8.88 times the effective value of the secondary phase voltage of the three-phase transformers. A further disadvantage is the need for a significant number of commutating components: 6 commutating capacitors, 6 commutating chokes and two specifically commutating transformers.

The above mentioned drawbacks are eliminated by a six-pulse thyristor direct frequency and voltage converter according to the invention, which is based on a single common switching circuit LC, consisting of a series combination of a commutation capacitor and a commutation choke, and a six-phase diode connected by its alternating side to the open winding of a three-phase load motor. A zero thyristor or an anti-parallel thyristor is connected to the DC side of the bridge. a common LC switching circuit is connected via two reversing thyristors. This

In addition, I is connected to a node of a thyristor thyristor node and the other is a serial thyristor to a node of a six-phase diode node rectifier. The alternating side-phase thyristor and diode node rectifiers are connected to opposite poles of three-phase diode bridges with an antiparallel short-circuit thyristor.

The higher effect of the six-pulse thyristor direct frequency converter and the voltage of the present invention is that a set of phase and non-coupled secondary voltage three-phase transformers is connected to the AC side of the six-phase diode bridge from which the common LC circuit is coupled. Therefore, the commutation capacitor is charged at a voltage of 1 / T times lower than in a previously known circuit. In the same ratio, it will reduce the stress on the semiconductor components. An advantage over the known circuit is also the saving of both specially wound commutating transformers as well as five communication chokes, although the number of semiconductor components has increased.

In the accompanying drawing, there is shown in the drawing one of the particular connections of a six-pulse styrofoam direct frequency converter and according to the invention.

The primary windings of the three-phase transformers 1 are connected to the power supply network. Each has three three-phase secondary windings. The ends of the secondary windings of one, respectively. the second three-phase transformer 1 is premultiplexed and connected at the beginning and end of the winding of the three-phase load motor 2, which is connected to the open triangle. The start of each of the three three-phase secondary windings of the three-phase transformers 1 are connected to the AC side of one of the six semiconductor switches of the node formed by the a phase diode bridge 2 and an anti-parallel short-circuit thyristor 12 on its one-way side.

Claims (1)

3 257802 The start and end of the winding of the three-phase load motor 2 are also connected to the alternating side of the six-phase diode bridge 2. Anode is connected to the cathode pole of its DC side, to the anode pole the cathode of the zero thyristor 5. Parallel to it via the cathode of the anode of the first , respectively. the anode and cathode of the second reversing thyristor 61 and 61, respectively; 62, a serial combination of a single common commutation dipole formed by a series combination of commutation choke 7 and commutation capacitor J5 is connected. One node of the commutation dipole 2r 2 'connected to the cathode of the second reversing thyristor 62 is connected to the anode node of the six-phase thyristor node rectifier while the second node, connected to the anode of the first reversing thyristor 61, is connected to the cathode six-phase diode node rectifier 10 via a serial thyristor 11. the thyristor node rectifier 9 is connected to the anode poles of the unidirectional side of the three phase diode bridges 2, wherein their cathode poles are connected to an alternating side of the six phase diode node rectifier 10; The multiplexing of the ends of the secondary windings of the three-phase transformers 2 allows the three winding load motors 2 to be formed on the individual windings, which consist of cyclically alternating segments of the combined secondary stresses of the three-phase transformers 2. of the network and the switching frequency of the tripping thyristors 12 The change in voltage on the windings of the three-phase load motor 2 is determined by the width-pulse control. Zero sections over time are given by the short-circuiting of the three-phase load motor winding 2 through the six-phase diode bridge i and the reset thyristor 5, wherein the respective short-circuit thyristors 12 are switched off when the series thyristor 11 and the corresponding thyristor thyristor node rectifier 9 are switched on. The two secondary thyristor coils on the windings of the three-phase load motor 2 are formed by simultaneously switching on the two short-circuit thyristors 12, one of which connects to the node a triple secondary winding, the other three winding windings of the second three-phase transformer. . 62 and commutation condenser j) are charged to the polarity needed to turn off the shorting thyristors 12. · Switching occurs by simultaneously applying the gate pulses to the serial thyristor 11 in the six-phase diode node rectifier 10 and to the two thyristors in the six-phase thyristor node rectifier 9 that are associated with the two short-circuiting thyristor 12 is switched off. The continuity of the three-phase load motor circuit 2 ensures simultaneous activation of the reset thyristor! OBJECT OF THE OUTSTAND The thyristor thyristor direct frequency and voltage converter consists of two three-phase transformers with three three-phase secondary windings, premultiplexed outlets connected to a three-phase load motor, the other outlets to the AC side of three-phase diodes with an anti-parallel short-circuit thyristor on the DC side, Sálejzo of a six-phase diode bridge, a six-phase thyristor node rectifier and a six-phase diode node rectifier with a series thyristor connected in its node and a common commutating dipole, characterized in that the AC side of the six-phase diode bridge (4) is connected to the open winding of the three-phase load motor (2) while a one-way counter is an anti-parallel connected resetting thyristor (5) and parallel to this via the antiseries of the first reversing thyristor (61) from one side, and a second reversing thyristor (62) from the other side is connected to a series combination of a commutating choke (7) and a commutation capacitor (8), forming a common commutating dipole, the first node of which with one of the polarizing thyristors (61,, ( 62) is connected to a non-uniform node of a six-phase thyristor node rectifier (9) connected by an alternating side with uneven poles of a one-way side of a six three-phase diode bridge (3, while a second node with a second one of polarity 257802 4 thyristors (62), (61), is connected via a serial thyristor (11) to an unbalanced node of a six-phase diode node rectifier 10, coupled on an alternating side to opposite poles of a single-directional side of a three-phase diode bridge, 3) with an antiparallel short-circuit thyristor (12f. 1 drawing