Analytical Modeling of Interior Permanent Magnet Machines With Auxiliary Notch Rotor

This paper introduces a two-dimensional (2-D) analytical model to predict the performance characteristics of interior permanent magnet (IPM) machines with arbitrary rotor geometry (e.g., auxiliary notch rotor and sinusoidal PM shape). The absence of cylindrical symmetry in such complex rotor structures with auxiliary notch rotor core and rectangular-shaped interior permanent magnets (PMs) poses challenges for solving 2-D boundary conditions and developing the analytical model. To address this issue interior PMs are first mapped to the rotor surface and replaced by sin-shaped PMs. In other words, the original IPM machine with auxiliary notch rotor is transformed into a surface mounted PM machine. Next, sin-shaped PMs are segmented into a number of small pieces to form cylindrical symmetry along the angular length of each piece. Finally, 2-D Maxwell equations are discretely solved in each segment and summated to calculate the resultant flux distribution. Meanwhile, the effects of stator slot’s are modeled with magnetizing current. The accuracy of analytical results are verified by Finite Element (FE), and experimental tests on the motor prototype.