4. Design Methods

The equivalent circuit model of the inductive feed [1, 2] and capacitive feed [3] resonant inductive WPT systems have been analyzed to extract the S-parameters and the input impedance. Nevertheless, this method of analysis results in complicated design procedures. For example, complex equations needed to be solved in order to obtain the conditions for the perfect impedance matching and maximum power transfer for the WPT systems presented in [1, 2, 4]. Other design methods, like the one explained in Sect. 4.2 [3], have been developed to yield concise design equations using impedance and admittance inverters. These design methods result in simple design equations that can indicate rapidly, and accurately, the perfect impedance matching conditions.