Design and Characterization of PCB Spiral Coils for Inductive Power Transfer in Medium-Voltage Applications

Coil design and operating frequency are key factors impacting the efficiency of the inductive power transfer system. This article presents the modeling of printed circuit board spiral coils, design optimization and analysis on coil geometry, and operating frequency for medium-voltage (MV) applications, such as auxiliary power supplies for MV converters. Analytic model considering the geometric distribution of the magnetic field is proposed to calculate with high accuracy equivalent electrical parameters of coils. For a defined design space and constraints, a large number of coils are designed to determine their performances and select optimal coil geometries. Selected coil designs are prototyped and experimentally verified under design-specific conditions. In addition, further characterization is performed considering variations of several parameters that can be encountered in practice.