Design of PMSM for EV Traction Using MSO Coil Considering AC Resistance According to Current Density and Parallel Circuit

As the EV traction system requires the PMSM to be driven at wide driving range, the PMSM for EV traction using Maximum Slot Occupation coil (MSO coil) has been designed in this paper. By applying the MSO coil, the high torque density was satisfied but additional loss by AC resistance at high speed became critical. In order to reduce the AC resistance of MSO coil, the following process was conducted. First, by analyzing the analytic method, the shape and number of conductor which depend on the current density and parallel circuit were chosen as the important parameter on AC resistance. By investigating the MSO coil with E-I core, the resistances of MSO coil at both low and high frequency were studied according to current density and parallel circuit. Based on the results above, the PMSM using MSO coil was designed in proper current density and parallel circuit to improve the efficiency at both base and maximum speed.