Current-Decomposition-Based Digital Phase Synchronization Method for BWPT System

Phase synchronization between the primary and secondary power converters is indispensable to achieve bidirectional wireless power transfer (BWPT). For sharing the phase information without any physical contact, traditionally, some wireless communication devices or auxiliary windings are proposed, yet with the disadvantages of low reliability and high cost caused by the electromagnetic interference and extra devices. This letter proposes a digital phase synchronization method for the BWPT system. Based on the active and reactive components of the ac current flowing into/out of the secondary high-frequency converter (HFC), the voltage phase of secondary HFC can be controlled to synchronize with that of primary HFC by adjusting the reactive current to be zero. The advantages of the proposed method are the fast response and high reliability for phase synchronization. A 1-kW prototype controlled by a field-programmable gate array is built to verify the proposed method. The experimental results prove that the system can quickly switch the power transmission direction in 2 ms with a maximum efficiency of 96.48% and can operate stably when the parameters perturbation occur. This letter is accompanied by an experimental video to prove the feasibility of the proposed method.