Optimization of Super Capacitor Buffered Dynamic Wireless Power Transfer System

Wireless power transfer (WPT) systems operating in megahertz (MHz) have advantages of small size and high tolerance for coil misalignment. Existing MHz WPT systems mostly focus on static scenarios. But in real applications, many systems require dynamic charging and it is desirable to achieve longest charging distance with fewer number of transmitting coils. In this paper, super capacitor (SC) is added to the receiving side as an energy buffer. SC stores energy when the coupling is strong, and releases energy when the coupling is weak. In a certain range, a larger capacitance lead to a higher distance between transmitting coil which can significantly reduce the construction cost. However, excessive capacitance of the SC will increase the weight and volume of the system which will reduce the receiver power density. Therefore, this paper uses genetic algorithm (GA) to optimize the pole spacing between two adjacent transmitting coils and capacitance of SC. A set of optimized parameters was selected for simulation verification. Simulation results match well with the theoretical analysis, which implies that compared to the dynamic WPT system without SC, the SC buffered WPT system can effectively increase power density and decrease construction cost.