Parameter identification of wireless power transfer systems using input voltage and current

Wireless power transfer (WPT) systems based on the use of resonators with high quality factors are highly sensitive to the parameters of the resonant tanks. While the inductance terms can be theoretically calculated, the mutual inductance terms require very accurate measurements of the coil dimensions, locations and orientations. Slight deviations of these measurements could therefore lead to significant errors. In addition, capacitors have fairly large tolerance in terms of their capacitance, making it difficult to assume their rated values in the determination of the optimal operating frequency of the WPT systems. In this paper, a parameter identification method for WPT systems based on the measurements of the input voltage and current is presented. Using an evolutionary algorithm, accurate parameter values required for modeling the WPT system can be determined. This method has been successfully illustrated in a 3-coil WPT system. Good agreements between calculated and measured parameters have been achieved.