A Novel WPT System with Digitally Closed-loop Control Featuring High Misalignment Tolerance

Abstract

Aiming at the problem that the misalignment of coils during wireless charging will cause instability of output voltage and rapid decrease of efficiency, this paper designs a wireless power transfer system featuring high misalignment tolerance. This paper analyzes the characteristic of LCC/S compensation topology, optimizes the coil and core of a loosely coupled transformer and designs a digitally closed-loop Buck converter. The controller, which improves response of the Buck converter by varying loop-gain, cross-over frequency and phase margin, is developed in continuous domain and then discretized to obtain digital form. Ultimately, a prototype with constant output power of 250 W is built. The energy transmission efficiency is as high as 89.8% and systems can still output a constant voltage, even if the offset reaches 57 mm.