Three-phase power converter with fail soft characteristics

Abstract

A DC-to-AC power converter for use with a three phase motor that allows the motor to continue to operate at reduced power in the event of a switch failure in the converter. This is accomplished by using parallel power semiconductor switch poles for each phase. The motor may be wound with parallel windings for each phase to aid current sharing of the parallel poles. This feature is not absolutely required, but the impedance of the windings help balance the currents in the parallel poles. The arrangement of parallel switch poles allows for continued operation of the motor at half of its rated power level in the event of a failure of one of the power switches. Switching frequency and duty cycle of the parallel poles are controlled by a single pulse width modulation signal which is connected to the two drive circuits that control the switches. Fuses, or other circuit disconnect devices are added between the power switch pole outputs and their respective windings of the motor to isolate a failed power switch.

Dependencies are inferred from the claim text.