Analysis and control development of IPM traction machines with skewed rotor using unskewed machine model

The paper presents a simplified analysis and control development method for IPM traction machines with skewed rotor using unskewed machine model. It is shown that the skewed machine characteristics under a given set of dq-axis currents could be obtained from the unskewed machine model using relevant modified dq-axis currents associated with the skewed information. Therefore, under the proposed method, the tested IPM machine model with skewed rotor could be rapidly derived from the unskewed machine model without FEA implementation for each skewed slice. It is demonstrated that in comparison with the FEA-based model, the proposed method could maintain up to 0.2% difference for both stator flux linkage and torque maps over dq-axis currents applied as well as 0.1% efficiency difference map over main torque speed operation. The proposed method is validated by FEA and measurement from a high-speed high-power (8000rpm, 80kW) IPM traction machine with skewed rotor.