A Frequency-Adaptive Synchronization Method for Bidirectional IPT Systems

Bidirectional inductive power transfer (BIPT) system is critical to vehicle-to-grid (V2G) and vehicle-to-vehicle (V2V) applications. In BIPT systems, the drive synchronization between primary converter and secondary converter is of essential importance. This paper presents a frequency-adaptive and parameter-independent synchronization method for BIPT systems, in which the so-called frequency-adaptive demodulation technique is suggested to realize synchronization control. The merit of the proposed method lies in that no matter what the resonant frequency and switching frequency are, the synchro angle can be controlled as needed, which means that the proposed method is independent of resonant parameters. Based on the proposed principle, a 7.98 kW BIPT prototype with series-series compensation topology is designed, and the experimental results confirm that the proposed method is frequency-adaptive and effective. The forward and backward experimental transmission efficiencies can achieve 97.7% and 97.3%, respectively, when the coupling coefficient is 0.31.