Optimization of wireless power transfer for mobile receivers using automatic digital capacitance tuning

We report on an automatic impedance tuning network for mobile receivers in magnetoquasistatic wireless power transfer (WPT). We experimentally investigate a WPT system with a mobile receiver placed over a 3 × 6 spatial grid and demonstrate that the impedance change due to spatial location can be compensated through the use of two digitally tunable capacitors. We show an improved power transfer efficiency of up to 80% using this technique.