Optimization Method for High-Order Wireless Power Transfer System Considering Gain Constraint and Components Stress

High-order resonant networks have the advantages of high system efficiency, small output ripple, and low component stress, which makes them suitable for high-power transportation electrification fields. However, the high design freedom inherent in high-order networks has not been fully considered in the existing studies. Therefore, in this article, a comprehensive optimization for network parameters with the constraint of fixed transmission gain and maximum component stress is done to improve its network performance. First, the relationship among network parameters, loop currents, transmission efficiency, and gain can be obtained according to the general circuit model. Then, parameters resonant conditions to reduce the loop currents and enhance transmission efficiency can be obtained. On the other hand, by adopting the Lagrange multiplier method, the specific value of network parameters can be deduced to achieve optimal transmission efficiency under fixed gain and component stress constraints. Based on the above analysis results, the parameters freedom of any given network can be utilized completely to obtain optimum performance, including efficiency enhancement, expected input and output characteristics, and components stress minimum. Finally, two experimental platforms, inductor-capacitor-capacitor (LCC)/LCC and LCC/series (LCC/S) networks for constant current and voltage, respectively, are built to verify the feasibility of the proposed optimization method.