Design Methodology for a Medium-Voltage Multilevel Inductive Power Transfer System with Excitation Coils

A multilevel inductive power transfer (MIPT) system employs multilevel converters and excitation coils to develop medium-voltage (MV) systems. The excitation coils have strong couplings with the transmitter coil, but they are galvanically isolated. Design variables of the MIPT system include the multilevel converter, resonant tank, and IPT coils. To design an efficient and cost-effective MIPT system, the designs of multilevel converter, resonant tank, and IPT coils should be simultaneously considered. However, previous studies did not investigate the relationships among the design variables, and co-optimization of the resonant tank and the multilevel converter has not been investigated yet. This study presents a design methodology for MIPT systems with excitation coils. Characteristics and performances of the MIPT system are analyzed to derive the design methodology. Losses and costs of the MIPT system are balanced using Pareto fronts. A 25 kV, 42-level IPT system with five receiver coils was designed to discuss the scalability of the proposed design method. In addition, a 12-level IPT system testbed was constructed using the design results. The IPT system was evaluated at 6 kV, and the achieved coil-to-coil and grid-to-load efficiencies were 91% and 87%, respectively.