Investigation of design methodology for non-rare-earth variable-flux switched-flux memory machines

This study presents a design methodology for a newly emerged switched-flux memory machine with low-cost non-rare-earth. The adoption of aluminium–nickel–cobalt magnet with low-coercive force enables the flexible air-gap flux control without unnecessary excitation loss. Hence, the excellent flux variability and high-efficiency sustainability within a wide-speed range can be achieved. Since geometric constraints exist among major parameters, a design trade-off should be established to facilitate the feasible design. Therefore, a simplified magnetic circuit is modelled to analytically determine the relationships among various parameters, and the generic design considerations including magnet grade selection and stator/rotor-pole combination are addressed, respectively. The influences of design parameters on back-electromotive force and torque capability are evaluated to aid the performance optimisation. A machine prototype is then fabricated to experimentally validate the theoretical analyses.