Dynamic Model of an External Rotor Hub-Motor Based on an Improved Magnetic Circuit Method

This article proposes an improved dynamic magnetic equivalent circuit (IDMEC) model for rapid modeling and analysis of external rotor hub motors. The model is meticulously modeled in three layers in the stator tooth crown region to account for local magnetic saturation, and reluctance mesh modeling is introduced in the air-gap region to increase model accuracy. The model shifts the dynamic execution region from the air-gap region to the rotor region, changing the dynamic switching strategy of the conventional model. The model only needs to change the permeance and magnet motive force (MMF) on the fixed magnetic circuit in the rotor area to achieve the dynamic switching of the model, which unifies the topology of the magnetic circuits in different rotor positions. It no longer needs to be modeled several times for different rotor positions, which improves the modeling efficiency. In addition, the modeling and calculation methods of the double-layer distributed winding MMF source are provided. Finally, the established dynamic magnetic circuit model was used to calculate the flux linkage, back electromotive force (EMF), air-gap flux density, and torque of the external rotor hub motor. The effectiveness of the model was verified by comparing it with finite element and experimental data.