Multi-Objective Design and Optimization of a Hybrid-Dual Rotor PMSM Using Magnetic Circuit Decoupling and WTSM Strategy

This paper presents a novel design and optimization methodology for hybrid-dual rotor permanent magnet synchronous machines (HDR-PMSMs) featuring a double-sided stator structure. The machine comprises two distinct rotor types, positioned with an offset angle relative to one another, which enables maximization of torque density. Consequently, the presence of numerous design variables on each rotor side significantly increases the complexity of the design and optimization process. To address this challenge, a combined strategy involving magnetic circuit decoupling (MCD) and waveform targeting surrogate modeling (WTSM) is adopted to facilitate multi-objective optimization. As part of the MCD approach, a set of analytical equations is developed to predict the magnetic flux density in the stator yoke. It is demonstrated that, under unsaturated conditions, the HDR-PMSM can be decoupled into two independently modeled rotor systems, effectively simplifying the overall optimization problem. Furthermore, the WTSM framework reduces the number of finite element (FE) simulations required to identify optimal designs. The effectiveness of the proposed method is validated through a multi-objective optimization process, targeting improvements in average torque, torque ripple, and permanent magnet (PM) volume, while ensuring safe magnetic operation through the consideration of anti-demagnetization constraints.