Constant Output Voltage and ZVS Control Strategy for Three-Phase Wireless Power Transfer System Under Asymmetric Resonant Parameters

Subject to the influences of temperature and manufacturing inconsistencies, the parameter consistency of compensation topologies in three-phase wireless power transfer (TPWPT) systems is often difficult to guarantee. As a result, conventional symmetric inverter control strategy struggles to maintain stable transmitting currents and achieve zero-voltage switching (ZVS) for the inverters. This article presents a constant-voltage output and ZVS control strategy under asymmetric resonant parameters in a three-phase system, based on a symmetric transmitting current control approach. By coordinating pulse duty cycles and phase shifts, symmetric transmitting currents are achieved, while dynamic fine-tuning of the operating frequency ensures ZVS across all power switches of the three-phase inverter. Furthermore, a compensation method for symmetric current control is introduced to correct the output voltage variations caused by frequency adjustment. Compared with conventional approaches, the proposed control strategy not only ensures stable system output but also maintains high operational efficiency. A prototype was constructed, and experimental results demonstrate that the proposed strategy achieves ZVS for all switches under asymmetric resonant conditions, improves the DC–DC efficiency from 92.66% to 93.35%, and maintains nearly constant output voltage.