Impact of Receiver Power and Coupling Coefficient on Resonant Frequency in Wireless Power Transfer System

Resonant wireless power transfer (WPT) is gaining popularity as a solution for wireless powering of electronic devices in multi-user environment where operating frequency must be fixed. This paper proposed a simulation model for parallel-serial topology of WPT system. Simulation model is verified by experimental measurement and used to analyze the impact which receiver power and coupling coefficient between transmitter and receiver have on resonant frequency of the system. Three resonant frequencies have been identified which correspond with local efficiency maximums. Criteria for resonant frequency shift evaluation is defined and conducted analysis has shown that by keeping the coupling coefficient under 0.1, the relative resonant frequency shift will not exceed 0.5%.