Modified Winding Function Analytical Analysis Method Based on Segmentation of Both Coil and Air Gap Distributions

Variable reluctance resolvers(VVRs) have been widely used as position sensors in harsh working conditions because of their advantages in high temperature resistance, insensitity to mechanical vibration, simple structure and so on. In previous work, a hybrid dual-stator machine with an inner-stator VRR radially integrated in a permanent magnet synchronous machine(PMSM) is proposed. The magnetic field distribution and the electromagnetic parameters of the internal machine are analyzed via the modified winding function approach(MWFA). However, the calculated distribution of air gap flux density differed from the finite element analysis(FEA) result at the slot opening. To solve this problem, the segmented winding function method(SWFM) is proposed, where both the air gap length and the coil distribution function are segmented considering the actual distributions of magnetic field and coils so that to achieve more precise analytical approach. With the proposed method, the air gap flux density and the self-inductance of the excitation winding are calculated, and the analytical results of both the SWFM and the MWFA are compared with FEA to verify the accuracy of the proposed method.