A primary side controller for inductive power transfer systems

Abstract

Inductive power transfer (IPT) technology is gaining popularity as an efficient wireless power transfer mechanism in numerous applications, ranging from microwatt bio-engineering implants to high power battery charging systems. A typical IPT system employs two separate controllers on both powering and receiving sides of the system to facilitate contactless power transfer in an efficient and controllable way. This paper presents a new primary side control technique for IPT, which requires only a single controller located on the powering side to effectively control the amount of `contactless' power delivery to the receiving side. In order to regulate the load voltage, the track current is controlled in the proposed technique by accurately estimating the mutual coupling and output voltage through the variation of reflected primary voltage. Theoretical analysis and simulated results are presented, with experimental measurements of a prototype IPT system to validate the viability of the proposed technique. In contrast to existing IPT systems, the proposed IPT system with only a single controller is low in cost, more efficient, and is expected to be the popular choice in applications such as biomedical implants.