Driving cycle-centric design optimization and experimental validation of high torque density outer rotor 8/18 MTSRM for an E-Bike

Abstract

This paper presents an innovative methodology for optimizing the design parameters of a 500 W low-speed outer rotor switched reluctance motor (OR-SRM) for an electric bicycle (E-bike) in accordance with a driving cycle. Design optimization of SRMs based on driving cycles has been minimally explored in the literature, with all existing research focusing exclusively on high-speed electric vehicle (EV) applications. These studies utilized computationally intensive dynamic current analysis methods to account for the significant dynamic effects incurred. Given the E-bike's low-speed characteristics, the present study mitigates the computational load of design optimization through static current analysis. A high torque density 8/18 OR-multi-teeth (MT) SRM topology has been proposed. The benefits of this topology, such as mass, cost, torque ripple reductions, and improved torque density, have been highlighted through a comparison with a conventional 6/10 OR-SRM topology. The reliability of the finite element analysis models used in this study is validated through experiments conducted on an 8/18 OR-MTSRM prototype. The multi-objective design optimization aims to maximize starting torque and minimize torque ripple and electromagnetic losses throughout the driving cycle. The efficacy of the optimization is confirmed by the enhancement in the performance parameters of the optimal design compared to the preliminary design. © 2025 Elsevier Ltd