Analytical model for magnetic‐geared double‐rotor machines and its d–q ‐axis determination

This study presents an analytical sub‐domain model for the prediction of various electromagnetic parameters of magnetic‐geared double‐rotor machine (MGDRM). By dividing the MGDRM into six sub‐domains and solving the Maxwell equations in polar coordinates for each region, the vector magnetic potential distribution can be derived. Subsequently, the flux density distribution, back electromotive force, and output torque, can be calculated. Furthermore, based on the proposed model, the equivalent d – q ‐axis is elaborated. Also, the corresponding d and q inductance can be obtained. It proves that the MGDRM can be regarded as a non‐salient‐pole synchronous machine. Besides, the power factor of the MGDRM under i d  = 0 control is deduced and optimised for the different thicknesses of modulators. In addition, the demagnetisation capability is analysed by adopting the sub‐domain model. Finally, the accuracy of proposed sub‐domain model for MGDRMs is validated via the finite‐element method (FEM).