Parameter Identification‐Based Variable Capacitor Tuning and Constant Output Voltage Control for WPT Systems

ABSTRACT In wireless power transfer (WPT) system, the relative position of the coupling mechanism affects the self‐inductance and mutual inductance of the coils. Changes in coil parameters further impact the performance of the resonant circuit, output stability, and system transmission efficiency. To address these issues, this paper proposes a method for real‐time identification of self‐inductance and mutual inductance. This approach requires no real‐time communication, only measuring the output current of the primary‐side inverter and the RMS current on the switch capacitor branch. Two current equations concerning self‐inductance and mutual inductance are constructed. Since solving higher‐order equations is cumbersome, this method is combined with a particle swarm optimization algorithm to transform the system parameter identification problem into an optimization function. This approach enables real‐time identification of self‐inductance and mutual inductance. When fluctuations in these parameters cause resonance circuit detuning, a switch‐controlled capacitor (SCC) is employed on the system's transmission side to maintain resonance. Based on the identified parameters, the inverter conduction angle is rapidly calculated to achieve constant‐voltage output control. Finally, a wireless power transfer experimental platform was constructed. The parameter identification errors for self‐inductance and mutual inductance were 3.7% and 3.2%. When the air gap distance is 4 cm, the peak efficiency of the system reaches 93.1%.