Stator Impedance Modeling Platform for the Electromagnetic Compatibility Aware Design of 3.7- To 7.5-KW Squirrel-Cage Induction Motors

This article presents an electromagnetic compatibility (EMC) aware motor design method based on the prediction of the impedances of a stator winding structure. The stator structure is divided into several two-dimensional parts, and their network parameters are extracted by electromagnetic (EM) simulations. Through conversion and synthesis of the multiport network parameters, the input impedance can be found for the full-winding structure. The calculated input impedance approximately follows the measured impedance of tested induction motors. The impedance calculation method has been realized in a parametric analysis platform to enable the EMC-aware design of induction motors. By using the platform, the variations of the input impedances by different design parameters can be analyzed along with consideration of loss and torque ripple. To verify the proposed method, prototype motors were assembled and the common-mode (CM) currents were measured under driving operation. The results show that the CM current can be reduced up to 10 dB in the frequency range of interest when the number of parallel circuit is reduced, as estimated from the calculated input impedances.