Adaptive Sliding-Mode Control for a Multiple-User Inductive Power Transfer System Without Need for Communication

A complicating aspect in the control design of resonant inductive power transfer systems is the absence of a direct communication link between primary and (multiple) secondary system sides. This paper introduces a new adaptive sliding-mode control surface, which continuously adapts the inductive system´s input power to the required, but unknown, variable load power. As a result, an indirect communication link is redundant. Furthermore, due to matching input and output power, optimum relative system efficiency is automatically guaranteed in the entire system´s output power range. The controller design, which has a simple analog implementation, has been verified with a dual-load experimental contactless system.