Robust Optimization for A 6.78-MHz Wireless Power Transfer System with Class E Rectifier

Class E rectifier is suitable for high-frequency rectification due to its soft-switching operation, which potentially improves the efficiency of wireless power transfer (WPT) systems working at MHz. In this paper, a robust optimization design is discussed for a 6.78-MHz WPT system using the Class E rectifier. In real WPT applications, the parameter variations are possible to be originated from the misalignment of coils, the change of load, and the varying equivalent resistance of rectifying diode under different power level. In this case, a robust optimization problem is formulated to find a solution of system design variables that is both optimal and insensitive to uncertainty of parameters. A genetic-based inner-outer algorithm is applied to solve this problem, where an explicit trade-off among efficiency and robustness is demonstrated in the optimization results. In the final experiments, the analytical results are proved to well match the experimental results. Compared with the WPT system using the conventional design, the proposed robust optimization can achieve an improved design with high efficiency, which is also robust against the variations of working conditions.