IPT System Efficiency Improvement Considering Loss Characteristics of Inverter and Resonant Circuit

As an efficiency improvement method for inductive power transfer (IPT) systems, there is a method that adjusts the load impedance of the resonant circuit to the appropriate value by the converters. Generally, this method has been used for efficiency maximization of resonant circuits. However, the efficiency characteristics of the converters have not been considered in the method. In other words, the converter is not always driven at the appropriate operation points. For this reason, the conventional method does not always give the highest efficiency in the overall system. Therefore, this paper shows a guideline for the efficiency improvement of a system, which consists of a resonant circuit and a primary-side converter. In addition, for the guideline, power loss models of the resonant circuit and the converter are constructed. And then, the effectiveness of the proposed guideline is confirmed by experiments. As a result, by controlling the system according to the guideline, the efficiency at the maximum power transfer improves by 0.35 pt in comparison with the conventional method.