Secondary-side-only control for high efficiency and desired power with two converters in wireless power transfer systems

In recent years, wireless power transfer has been a popular research topic because it allows both static and dynamic charging without using cables, thus easing the process for the user. However, achieving high efficiency and desired power corresponding to the load at any time is important. Communication between sides is often used, but sometimes its operation is not guaranteed because of harsh environmental conditions or malfunctioning. This paper addresses this problem by proposing a novel yet simple control strategy. It consists of simultaneous regulation of both power and efficiency by the secondary side alone, without communication with the primary side. When the primary side is not manipulated, the power is controlled by an AC/DC converter by using a two-mode control. On the other hand, the efficiency is controlled by a DC/DC converter by adjusting the DC link voltage to a reference value related to the maximum wireless transmitting efficiency. In this paper, the control concept as well as the design are provided. The proposed control shows a good trade-off by achieving power regulation capability at the cost of slight reduction in efficiency when compared to the currently existing state-of-the-art control. © 2017 The Institute of Electrical Engineers of Japan.