A Digital Phase Synchronization Method for Bidirectional Inductive Power Transfer

Bidirectional inductive power transfer (BIPT) systems are of particular interest for electrical vehicles for their enabling power to exchange between grid and vehicle. In BIPT systems, it is critical to keep the voltage phasors of the primary-side and secondary-side converters synchronized to regulate the power flow. In this article, the basic operation and steady-state characteristics of the BIPT system are introduced. A phase synchronization method for BIPT systems, which does not require any communication between primary- and secondary-side controllers or complicated hardware, is proposed in this article. To assist the design of the synchronization controller, the large-signal model and small-signal model of the BIPT system are derived. Based on the derived model of the system, the controller design for the phase synchronization method is proposed, considering the coupling between the synchronization controller and the BIPT main circuit and the clock frequency deviation between the primary-side and secondary-side controllers. The parameter sensitivity of the proposed method is analyzed. The large-signal and small-signal models are verified through simulations. And the experimental verification of the phase synchronization method shows that the BIPT system with the proposed phase synchronization method has a fast transient response as well as a stable steady-state performance.