Surrogate and Correlation- based Optimization of Out-Rotor PMSM: A Case Study on e-Bike with Enhanced Halbach Array

The growing demand for eco-friendly transportation has significantly increased the popularity of electric bicycles. This paper focuses on the optimization and design of an outer rotor permanent magnet synchronous motor (ORPMSM) for electric bicycle applications. The design challenges include such as torque ripple, cogging torque, and efficiency. A multi-objective optimization approach, combining the Non-dominated Sorting Genetic Algorithm II (NSGA-II) and a surrogate model, is employed to enhance both electrical and mechanical performance. The results demonstrate considerable improvements in torque density, efficiency and reduced cogging torque. Furthermore, the use of a modified Halbach array in the rotor design minimizes demagnetization effects under severe operating conditions, leading to increased reliability and performance. The optimized motor design was validated through Finite Element Method (FEM) simulations, demonstrating a close match with the optimization results.