I. Intoduction
Contactless power supply system or wireless power transfer (WPT), a century old concept has caught up pace in the last decade due to its advantages over wired power transfer. Growing into two main application of charging and direct power supply, the technology has been widely experimented globally. EV charging [1], phone charging [2], charging of wireless sensor [3] and direct powering of biomedical sensors [4] are some of the application targets of the researchers in WPT. Apart from the research, market of WPT technology integrated devices is growing mainly due to the convenience and comfort WPT technology adds to the devices. In these devices WPT is enabled either through coupling two inductors in purely inductive manner or resonant manner. Resonant inductive manner power transfer has a stronger performance characteristic in low voltage and long distance power transfer applications over noncompensated or inductively coupled WPT [5]. Addition of compensation capacitor to the respective coils makes the coils purely resistive at the selected resonance frequency, reducing the impedance, VA rating and achieving higher system efficiencies [6]. Wireless inductive charger system is similar to a transformer without core. Circular or square shaped spiral coils are connected to the source or transmitter side coil and load or receiver side coil [7]. Alternating magnetic field generated by current flowing in transmitter coil (TxC) links with the receiver coil (RxC) to accomplish power transfer over air medium. This can be accomplished for static as well as dynamic motion of the devices.