An Optimizable Circuit Structure for High-Efficiency Wireless Power Transfer

Since the magnetically resonant coupling was suggested for wireless power transfer (WPT), the theoretical analysis and experimental verifications of several resonant coupling structures have been investigated by several groups. Series-resonant and shunt-resonant structures are two common circuit models which are widely used in WPT. Here, a simple circuit topological structure, the series-shunt mixed-resonant coupling, is presented with better performance in the transfer distance and efficiency. In the experimental verification, a pair of resonant coils with 10-cm diameter was used. The experimental results show that high efficiency of 85% was achieved at a distance of 10 cm (one relative distance) and 45% efficiency at 20 cm (two relative distances). The proposed structure has another advantage that circuit parameters can be easily optimized for high transfer efficiency under different distances.