Study on the Optimal Switching Frequency for Maximum Wireless Power Transfer in a Variable Airgap System

This paper presents the optimal switching frequency for maximum wireless power transfer (WPT) used in railway applications that have a variable airgap. Voltage gain is one of key elements judging the system performance, and can be presented as a function of the switching frequency and number of primary winding turns. The optimal switching frequency in the given parameters for WPT has been investigated in detail using a simulation. From the results, the optimal switching frequency obtained for maximum power transfer according to the design variables such as airgap, number of primary windings, mean length turns, and leakage flux, was different from the resonant frequency for maximum efficiency.