Pulse-width-modulated static inverter - has fault detecting system for input overvoltages etc. and initiating given shut-down operations at specified times

摘要

The static inverter is controlled by a modulated signal obtained by comparing a modulating wave with a carrier wave. A fault detector detects at least one fault e.g. overcurrent and overvoltage at the inverter's input. A limiter reduces the modulating wave's voltage level to zero when one of the faults occurs at a specified point in time and also disconnects all gate signals to the inverter's thyristors. Two or more thyristors suppress the commutating operations on the three conducting thyristors at a second specified point in time. The appearance of a fault signal resets the inverter ready for a soft start when the fault signal disappears.