Efficiency optimization of on-road charging for electrical vehicles

The paper introduces an on-road charging system for several electrical vehicles (EV) at the same time based on magnetic resonant coupled wireless power transfer (WPT). To analyze the proposed system, an equivalent circuit model of the system with single longer transmitting coil and several shorter receiving coils is presented. System efficiency is of particular interest and is found to be determined by power loss factor, coupling coefficient, resonator quality factors, load amounts and load resistances through analysis. Efficiency optimization by adjusting load resistances in according to load amount variations is derived. For the verification of theoretical analysis, an experimental prototype is implemented. It is shown that with the proposed strategy, a 90% maximum efficiency can be achieved regardless of the variations of load amounts.