Design and analysis of surface-mounted-type variable flux permanent magnet motor for wide-speed range applications

Recent studies have indicated that there is a high demand for high-efficiency machines used for home applications, such as washing machines and air conditioners. Such applications require components with high efficiency and high power density such as permanent magnet (PM) machines. In particular, variable-flux PM (VFPM) machines using a low-coercive force magnetic material have been studied extensively in terms of their potential to extend the flux-weakening range of PM machines and to improve efficiency. In previous studies, hybrid-excited machines with field coils, machines that require mechanical adjustments, and machines that involve other means of varying the flux with an interior PM have been studied and documented. Therefore, in this paper, we present the design and analysis of a surface-mounted-type VFPM motor for wide-speed range applications.