A fault tolerant control system for hexagram inverter motor drive

In this paper, a fault tolerant control method for hexagram inverter motor drive is proposed. Due to its unique topology, the hexagram inverter is able to tolerate certain degree of switch failure with a proper control method. The proposed method consists of fault detection, fault isolation and post fault control. A simple fault isolation method is to use fuses in the DC links to disable the whole inverter module with switch failure. When a fault is detected in one inverter module, it is isolated by turning on all switches temporarily to blow out the fuse in the DC link, the gate drive signals for this faulty inverter module and its interconnecting legs are then disabled. After one inverter module is disabled, the hexagram inverter works in the post fault two-phase mode. The post fault control algorithm is initiated to control the two remaining output currents in order to maintain a smooth torque operation for the motor drive. Simulations and a small-scale PMSM motor drive experiment verified the proposed fault tolerant control system design.