Multi-Stage Optimization Scheme for Partitioned Magnet Pole Variable-Leakage-Flux Machine Considering Flux-Adjustable Range

This paper focuses on a multi-stage optimization scheme for variable-leakage-flux machines (VLFMs), where the leakage flux is passively controlled by armature-reaction-induced magnetic saturation. In VLFMs, the magnetic flux is regulated by the flux weakening (FW) method and controllable leakage flux. This intrinsic coupling complicates the consideration in the flux-adjustable range during the optimization procedure, thereby limiting the full utilization of the inherent advantages of the VLF property to optimize the overall performance. Therefore, a novel design optimization scheme is developed for the VLFM in this paper, which can well decouple the armature reaction and VLF property by employing a three-stage field-circuit coupled model. The proposed model accounts for three representative operating conditions. In the first stage, key performance requirements like peak torque at low speed are considered. In the second and third stages, the minimum and maximum q-axis currents are applied, respectively, allowing direct acquisition of the PM flux linkage while eliminating the influence of the d-axis armature reaction. Consequently, the flux-adjustable range can be directly calculated and optimized in the optimization procedure. Afterwards, the proposed design optimization scheme is implemented on a recently developed partitioned magnet pole VLFM (PMP-VLFM) to obtain an optimal design. Finally, finite element (FE) simulations and experimental tests are carried out to verify the feasibility of the proposed design optimization scheme.