Wireless Phase - Locked Loop control for inductive Power Transfer Systems

Power transfer and efficiency maximization are the main aims in Inductive Power Transfer Systems (IPTSs) control. Misalignment between the magnetically coupled coils is inevitable in real life conditions and its impact in the power transfer capability of such systems is significant. This work presents a simple, yet robust technique for real-time, wireless tracking of the optimal operational frequency of an IPTS under different coupling conditions. The control is implemented by a Phase-Locked Loop (PLL). The phase of the load current signal is optically transmitted to the primary, where the PLL synchronizes the inverter output voltage to that signal. Experimental results on a secondary-side series compensated and a series-series compensated IPTS prototype show fast and accurate response, unaffected by bifurcation phenomena.