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Thyristor Swiching Circuits

IP.com Disclosure Number: IPCOM000087195D
Original Publication Date: 1976-Dec-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 48K

Publishing Venue

IBM

Related People

Patel, DC: AUTHOR

Abstract

A thyristor inverter is described having a number of parallel paths, the thyristors in each path being fired successively to provide high frequency operation.

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Thyristor Swiching Circuits

A thyristor inverter is described having a number of parallel paths, the thyristors in each path being fired successively to provide high frequency operation.

Fig. 1 shows two parallel path inverters. In the circuit the transformer with an output winding and center primary, together with input choke L1 and capacitor C1, are conventional.

Two parallel paths are used, each tuned to a frequency of less than half output frequency f by center tapped inductors L2, L3 and commutating capacitors C2, C3 connected across anodes of thyristors T1, T3 and T2, T4, respectively. The thyristors are triggered successively so that thyristors in each path fire alternately. As commutating capacitors and inductors are tuned to provide capacitive reactance, the voltage across the inductor lags the fundamental component of the current by approximately 90 degrees. Fig. 2 shows the voltage waveforms across 5-1 and 5-3.

When T1 is turned off, thyristors T2, T3 and T4 conduct in that sequence. Fig. 3 shows the contribution to the voltage across T1 that is made by the switching of the other thyristors. Fig. 4 shows the total voltage across T1 after turn OFF, and the circuit is so arranged that this voltage does not become positive until 5/6ths of a completed cycle has elapsed.

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