Transistor Diagnostic Strategies and Extended Operation Under One-Transistor Trigger Suppression in Inverter Power Drives

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, an appropriate fault-accommodating control method using one-transistor trigger suppression control relieves electrical overstress being applied to the degraded transistor to maintain motor operation, thus avoiding an inverter failure. Simulations and experimental tests demonstrate the feasibility of the proposed method for motor start-up even with a suboptimal control technique of constant V/f type. Also discussed are advantages and potential drawbacks of this technique.