Experimental fault-tolerant control of a PMSM drive

The paper describes the study and experimental verification of remedial strategies against failures occurring in the inverter power devices of a PM synchronous motor drive. The basic idea for designing a fault-tolerant drive consists in incorporating a fourth leg into the inverter stage, which has the same topology and capabilities of the other conventional ones. This represents a minimal redundancy that, when appropriately connected and controlled, allows the drive to face a power device fault condition with smooth torque. The proposed control strategy also fits interior permanent magnet motor drives, which can operate even above the base speed, where a proper flux-weakening current control is adopted.