Optimization design and research of an interior double-radial asymmetric permanent magnet and salient-pole electromagnetic hybrid excitation generator for vehicles

To address the limitations of flux regulation in traditional permanent magnet synchronous generators and the low power density of electrically excited generators, an interior double-radial asymmetric permanent magnet (PM) and salient-pole electromagnetic hybrid excitation generator are introduced in this study. Equations for the no-load induced electromotive force, the voltage adjustment range, and the total harmonic distortion (THD) are derived theoretically through the analysis of generator parameter relationships. The optimization parameters include the offset angles of the double-layer asymmetric PMs and the structural parameters of the salient-pole rotor. A multi-objective optimization model is established with the no-load induced electromotive force amplitude, the voltage adjustment range, and the THD as the objectives. Samples are generated by Latin Hypercube Sampling, followed by sensitivity analysis of the optimization parameters. The optimization parameters are then screened using Pareto front analysis and a defined parameter matching coefficient. The optimal magnet pole parameters are determined. As a result of optimization, the no-load induced electromotive force amplitude increases by 18.7%, the voltage adjustment range expands by 17.6%, and the THD decreases by 38.2%. Finally, a prototype is fabricated and tested, and the results confirm both the accuracy of the theoretical analysis and the effectiveness of the optimization method. The output characteristics of the designed generator are thereby significantly improved.