Adaptive position alignment for wireless charging system with mutual inductance estimation and P&O algorithms employ only primary-side electrical parameters

Position alignment between the transmitter and the receiver is vital for wireless charging system (WCS) because misalignment influences system efficiency, power transfer capability, and magnetic field distribution. Based on the primary-side electrical parameters, the mutual inductance estimation and perturbation and observation (P&O) algorithms are proposed to achieve the adaptive position alignment for the inductor-capacitor-inductor-series (LCL-S) compensated WCS through the movable transmitter. Based on the relationship between primary-side active power and mutual inductance, the feedback impedance theory and quadrature transformation (QT) algorithms are proposed to estimate the mutual inductance. Combined with the misalignment characteristic of circular magnetic coupler, the position alignment that is achieved by P&O algorithm and estimated mutual inductance. The simulation and experimental results verify the following conclusions: The mutual inductance estimation is suitable for different magnetic coupler and compensation topologies, and the accuracy of the estimated mutual inductance is suitable for practical applications. Compared with traditional active power method, the QT algorithm that calculates is more suitable for WCS that features high operating frequency. Combined with the proposed algorithms, high-system performance and fully automatic charging are ensured by the adaptive position alignment method.