Analysis and Elimination of Power Oscillation in Inductive Power Transfer Systems With Active Rectifier

Normally, an inductive power transfer (IPT) system with an active rectifier adopts two controllers, one each for the primary and secondary sides to separately control two converters. However, the frequency out-of-synchronization of two independent controllers will cause periodic power oscillations, which eventually lead to the system breakdown. To achieve frequency synchronization and eliminate power oscillation without any bilateral communications, this article proposes an approach that autonomously drives bridges of the active rectifier with zero-crossing signal captured from the secondary resonant current. Specifically, this article provides in-depth analyses of dual-side phase shift control modes, the transient and steady-state processes of bus voltage establishment in the synchronous rectification, and the power oscillation mechanism caused by random frequency differences of two controllers. Besides, by adjusting the delay time of the external zero-crossing signal triggered by the input of digital signal processor (DSP), the direction and magnitude of the transferred power can be flexibly regulated. The experimental study is conducted to validate the feasibility of the proposed method based on a 2.2-kW IPT experimental platform.