Coil design and operating frequency are key factors impacting the efficiency of inductive power transfer system. This paper presents the modeling of PCB spiral coils, design optimization and analysis on coil geometry and operating frequency for medium voltage applications, such as auxiliary power supplies for medium voltage 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 in order 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.