Comparisons of MOSFET and Relay Switches in Impedance Matching Networks for Wireless Power Transfer

Abstract

This paper presents the comparison between using MOSFET and relay switches in impedance matching networks (IMN) for inductive wireless power transfer (WPT). Complex IMN can be designed with multiple tuning branches which match the system with the optimum impedance. In such cases, it is required for the branches to be turned on and off accordingly. This is achieved through the use of switches. Existing research have mainly used electromechanical relays to perform the switching. However, relays have the disadvantage of increasing the IMN size, especially in complex designs. As an alternative, the MOSFET can be implemented as a switch with a smaller footprint. It is concluded that the MOSFET AC switch is a suitable option instead of relays but it requires careful consideration when implemented due to its parasitic elements.