An improved starting strategy for voltage-source inverter fed three phase induction motor drives under inverter fault conditions

Three phase voltage-fed inverter induction motor drives are prone to shoot through and other inverter faults that cause the drive system to shut down. The paper describes a novel strategy for restarting the drive in variable voltage variable frequency single phase mode in the presence of open base d rive and shoot through fault in the inverter. The proposed method requires only the motor terminal voltages and currents to be measured. Therefore, it can be applied to even low performance open loop drives with the addition of two motor terminal voltage sensors. The starting algorithm has been veri fied by computer simulation and experiments on a 1 hp laboratory prototype. Experimental results are in good agreement with simulation predictions. Th e starting strategy described in this paper is expected to provide an econo mic alternative to more expensive redundancy techniques which find justific ation only in a few specialized applications.