Parameter Extraction Technique for Evaluation of Inductive and Capacitive Elements of Three-Winding Coupled Inductor

Wide band gap devices have enabled miniaturization of magnetic components to enhance the power density of the converter. However, parasitic components become dominant at higher switching frequencies that actuate unwanted electromagnetic interference issues. Therefore, it is critical to model and evaluate them in compact magnetic structures. Since multiwinding coupled inductive structures are essential part of multiphase converters, this paper introduces a measurement method to compute the parasitic elements of a three-winding coupled inductor. Results of the proposed method are verified by measuring the high-frequency emissions of the high step-up converter with two inductor structures. Both inductors had similar inductances but different physical dimensions. With application of the proposed measurement methodology, parasitic capacitances of both inductors were computed. Results showed that one inductor structure has higher parasitic capacitance than the other. Since, high-frequency emissions of the converter directly depends on the parasitic capacitance of the inductor structure, emission profile of the converter showed that converter indeed had lower noise peaks when inductor with lower capacitance was employed. Hence, these results validate the capacitance trend as predicted by the proposed modeling technique. This method can be employed to any multiwinding coupled inductor to compute its parasitics to optimize the required EMI filters.