Inductor-Aid Step-Up LLC Resonant Wireless Power Transfer

An inductor-aid step-up LLC wireless power transfer (WPT) system is proposed in this paper. It could step up the WPT output voltage beyond the conventional LLC series-series (SS) compensation method. Employing a parallel inductor with the transmitter coil to lessen the circuit impedance thus the inverter exhibits a new gain curve. The constant frequency operation and simple control of two series active switches in the parallel inductor branch shows a practical improvement of conventional constant frequency LLC WPT system, in terms of voltage demand, new standards and applications. Even the frequency modulation LLC WPT system could be benefited from this enhanced topology rather than to deteriorate the inverter current stress and unnecessary over-rating of magnetic components. The receiver side compensation tank has no additional voltage drop and overcurrent. A 300W prototype has been constructed to validate the concept and performed at 90% efficiency.