Study of the thermal effects of a five-phase permanent magnet assisted synchronous reluctance motor under fault tolerant control

This paper presents a study on the thermal effects of a five-phase permanent magnet assisted synchronous reluctance motor (PMa-SynRM) under various fault conditions. The major advantage of a five-phase system is the additional number of phases which make it suitable for fault tolerant control in critical service applications. However, under the fault tolerant control (FTC), to maintain maximum torque, the phase currents are changed (magnitude and phase) in the remaining healthy phases. This change results in higher copper losses and heat generated in the healthy phases. Additionally, under FTC, the temperature rises unevenly inside the machine which leads to unbalanced magnetic pull. Due to this unbalanced magnetic pull, the actual torque capability of the machine reduces which may seem counterproductive to the fault tolerant advantage of the system. In this study, the temperature sensitivity of a five-phase PMaSynRM under FTC has been investigated through finite element (FE) analysis. The experimental analysis has been conducted on a 5 hp five-phase motor drive system.