Design And Optimization Of Flux-modulated Hub Motors For Electric Vehicles

Electric vehicles play an important role in environmental protection and resource conservation.An electric vehicle with excellent performance will inevitably require a high-performance drive motor,whose drive motor needs to meet the requirements of high power density,high torque density,high efficiency,wide speed range and strong overload capability.Permanent magnet gears have good running performance under the condition of low speed and high torque.The flux-modulated compound motor combining the permanent magnet gear and the permanent magnet motor not only has the advantages that the permanent magnet gear can change the rotation speed and direction at any time and the overload protection,but also has the advantages of high power density and high reliability of the permanent magnet motor.The design of electric vehicles driven by flux-modulated hub motors is flexible and diverse,and the structure is simple and compact.It has unique advantages in the driving system of electric vehicles.Based on the understanding of the development status of flux-modulated motors at home and abroad,this thesis introduces the working principle of permanent magnet gears and flux-modulated motors in detail.Four kinds of flux-modulated compound motors with different topologies are designed by finite element software Maxwell.The differences in electromagnetic performance among the four topologies are analyzed from the same topology,different operating modes and different topologies,the same operating mode.A topological structure with relatively good performance is selected for parametric modeling.Multi-parameter and multi-objective optimization is performed using Maxwell's own optimization tool.The optimized model was compared with the pre-optimization model to confirm that the optimized motor model is more competitive in performance.Secondly,a sinusoidal-permeance flux-modulated motor is designed and simulated by finite element method.Compared with the original design model,it is confirmed that the sinusoidal-permeance modulating rotor has outstanding performance in reducing the air gap permeability,eliminating the invalid harmonics and reducing the torque ripple.