Investigation into Fault Tolerant Capability of a Triple Redundant PMA SynRM Drive

Fault tolerant machine drives are being favored in safety critical applications, thus they are being actively investigated. However, most of the solutions address the winding or switch open circuit only, which is insufficient since intra-phase and inter-phase turn short circuits are more likely in the machine drives as a result of insulation degradation, and the consequences are usually catastrophic. Magnets and capacitor may also fail and cause damage during operation. All these faults should be properly addressed in fault tolerant machine drives for safety critical applications. Hence, a triple redundant, 9 phase (3x3phase) permanent magnet assisted synchronous reluctance machine (PMA SynRM) drive is presented by investigating the fault tolerances against various faults. The different fault behaviors are evaluated and the corresponding fault tolerant capabilities are analyzed. The machine fault tolerance is examined on a 35kW prototype drive. Both the analysis and experimental tests demonstrate that the machine drive exhibits excellent fault tolerant capability under most common types of faults, including the intra-phase and inter-phase short circuit, uncontrolled rectification, demagnetization and DC capacitor fault.