Primary Side Control Method of Wireless Power Transmission System Based on Load Resistance Identification

The variation of load resistance of the magnetic coupling resonance wireless power transmission system has a great impact on the system performance. To address this problem, this paper analyzes the equivalent circuit of a magnetic coupling resonance network and calculates the load resistance using the relationship between the system secondary impedance and the primary voltage and current. The relationship between the secondary voltage of the resonant network and the primary voltage of the system is proposed to adjust the output voltage of the primary PFC circuit and the phase shift angle of the inverter circuit in real time to achieve stable control before and after the change of load resistance. An experimental platform for primary-side separately controlled wireless charging based on load resistance identification is built. The experimental results demonstrate that the identification results are accurate, the system achieves constant-current and constant-voltage operation when the load resistance changes during the charging process, without the primary and secondary side communication devices.