Postfault Control Strategy for the Hexagram Inverter Motor Drive

This paper discusses the fault tolerance ability of the hexagram inverter motor drive. Due to its unique interconnecting nature, the hexagram inverter can tolerate one leg failure without modifying the power circuit topology. In the event of one leg failure, the control circuit can reconfigure the trigger signals to maintain a smooth torque operation at a reduced power level. When a leg fails within the inner interconnecting loop, no special postfault strategy is needed; the hexagram inverter can still work properly. When a leg fails outside of the interconnecting loop, a new postfault control strategy is initiated, which controls the two remaining phase currents to maintain an operation with smooth torque. The simulation and experimental results have shown that the hexagram inverter can maintain its operation with smooth torque after a fault.