Impedance Matching Network Optimization to Maximize Efficiency and Energy Transfer of WPT Systems

This paper presents an analytical optimization method for calculating the optimal stored energy in the magnetic field generated by a wireless power transfer (WPT) coupler. The ratio between the energy stored in the magnetic field and transferred power is derived to optimize the driving point impedance, which in turn determines the efficiency of the system. A new parameter, reactance mismatch coefficient, is defined to quantify the impact of impedance mismatch on efficiency. Furthermore, the wireless power transfer figure-of-merit (FOM) is redefined to consider the impedance matching capability. Circuit simulation is developed to validate the proposed methodologies and associated equations.