Maximum Torque Output Control of Hybrid Permanent Magnet Axial Field Flux-switching Memory Machine

Memory machines (MMs) equipped with low coercive force (LCF) permanent magnet (PM), e.g. AlNiCo and high coercive force (HCF) PM, e.g. NdFeB, possess the advantages of high power density, high efficiency and high efficient flux-regulation capability. In this paper, a robust control strategy to achieve the maximum torque output in different speed region is proposed and implemented on a hybrid permanent magnet axial field flux-switching memory machine (HPM-AFFSMM). Different from the method strongly depending on the parameter characteristics of machine, the proposed method enables the stator-PM MMs to be seen as various PMSMs with different "rated speed" when the magnetization state (MS) of LCF PM are selected. As a result, the trajectory of maximum torque output control in the different speed region can be easily decided. Furthermore, the flux-regulation pulse is determined by comparing the estimated PM flux with the required one corresponding to the maximum speed of different speed interval. In order to properly magnetize or demagnetize the LCF PM, an adaptive PM flux observer, which is robust to machine parameters, is presented to observe the actual PM flux. Both the simulation and experimentation are carried out to verify the validity of the proposed control strategy.