Fault-Tolerant Design and Control of Hybrid Excitation Axial Field Flux-Switching Permanent Magnet Machines

Abstract

Fault tolerance of drive motor is a critical facet for many applications, such as aerospace, traffic, and military. Because continuous operation under fault conditions can improve the reliability and safety of the whole system, many researchers are attracted to investigate the fault tolerant machines. [1] proposed a three-phase axial flux-switching permanent magnet machine (AFFSPMM). Because of the simple and robust rotor, short axial size, and high torque density, it is suitable to directly drive electric vehicle (EV). However, it is noticed that the fault tolerance of AFFSPMM should be considered in order to keep the drive system of EV operate safely under the fault conditions. It was found in [2], [3] that E-core topology could reduce magnet volumes and mutual coupling between phases in contrast with U-core one. However, the air-gap field was not able to be regulated due to only excitation of permanent magnets for the two AFFSPM machines, and therefore [4] proposed a hybrid excitation topology on the basis of E-core AFFSPMM, viz. a hybrid excitation axial flux-switching permanent magnet machine (HEAFFSPMM), in which the air-gap flux could be regulated by the DC excitation current. In this paper, the HEAFFSPMM is optimized for achieving better fault-tolerance with reference of the original U-core AFFSPMM, and the performances are compared and analyzed between the two machines. A novel fault-tolerant control method is proposed to improve the fault-tolerant capability by virtue of the special structure of the HEAFFSPMM.