Surge protection circuit for converter - includes thyristor to block firing pulses to rectifier section, operating with mechanical switch

摘要

The converter with a d.c. intermediate circuit is suitable for the supply for a rotary machine and is protected against surges by a circuit with a rectifier section (2) at the input connected by a smoothing choke (3) and capacitor (4) is an inverter section (8). This is followed by a transformer (9) connecting to a further network (10). Between the rectifier and inverter is incorporated a mechanical switch (6) followed by an electronic switch (5) such as a thyristor, with a resistor (7) in parallel with the mechanical switch. The thyristor blocks all firing pulses for the thyristors of the inverter, and the mechanical switch is closed. This switch opens after between 1 and 1.5 periods of the network (10) at the output.