Forced commutation of inverters with variable DC supply - involves suppression elements to limit dynamic loads on thyristors during switching

摘要

The application is to inverters operating from a variable d.c. supply and using two independent supplies for charging the commutating circuits, each supply being about half the voltage of the main supply, as in 2012893. The present addition provides circuit elements to limit the di/dt imposed on the thyristors during switching to values not exceeding the device rated values, and also to ensure adequate turn off time, tq. Capacitor-resistor circuits are added to the commutation capacitor charging circuit thyristors and diodes. A saturable choke is placed in series with the commutating capacitor and square loop chokes in series with the charging thyristor and main power supply. Capacitors are also added across the commutating thyristors.