Analytical Model for No-Load Rotor Bracket Loss of Axial flux Hybrid Excitation Motor based on Subdomain Method

Due to the drawbacks of high computational complexity and long time consumption when calculating the loss of the rotor bracket using three-dimensional finite element method, this paper proposes a field coupling analysis method based on subdomain method and circuit equations to calculate the loss of the no-load rotor bracket of a composite axial hybrid excitation motor. Firstly, the motor is divided into air gap subdomains and slot subdomains adjacent to the ferromagnetic poles. The DC excitation winding is equivalent to the current sheet located at the junction of the air gap subdomain and the inner diameter of the stator. The subdomain method is used to analyze and calculate the air gap magnetic field of the motor. Due to the relative motion of the fixed rotor, the magnetic field in the rotor bracket changes, resulting in the generation of induced electromotive force in the rotor bracket. The rotor bracket is equivalent to a network model of resistors, and the resistance network method is used to calculate the losses of the rotor bracket. Finally, the correctness of the analytical model for rotor support loss was verified through a no-load excitation experiment of a composite axial hybrid excitation motor.