Inverter power drive transistor diagnostic and extended operation under one-transistor trigger suppression

A fault-accommodation technique proposed for inverter drive systems extends the operation of an electrical power drive during an incipient power transistor fault. The discussed technique utilizes diagnostic methods to identify and isolate degraded power transistors. Once isolated, a suitable fault-accommodating control method using one-transistor trigger suppression (OTTS) control relieves electrical overstress applied to the degraded transistor to maintain operation of the motor while avoiding an inverter failure. Feasibility of the proposed method is demonstrated using V/f and vector techniques with an additional external fuzzy control for startup and steady-state conditions. Also discussed are advantages and potential drawbacks of this technique.