A Method Based on Vector-Summing to Reduce Output Power Fluctuation for EV-DWPT System With the Passive LC Network

Due to the decrease in coupling in the transition area of the primary segment, an undesired fluctuation in output power is expected for most existing solutions. This article, therefore, proposes a method based on the vector summing to reduce the output power fluctuations in electric vehicle dynamic wireless power transfer (EV-DWPT) systems. A simple but well-designed passive LC network is employed between the primary segments. This additional passive LC network in adjacent segments can sum an induced voltage vector provided by the primary segment. The amplitude of the induced voltage vector at the secondary coil is maintained quasi-constant as the vehicle charges dynamically. This ultimately reduces the fluctuation of output power and allows for quick transitions between primary segments. Based on the mathematical model built and vector-summing analysis, the design method for the passive LC network is provided, including the configuration of the passive coil and its compensation capacitor. Taking the entire dynamic process into account, an 8.3 kW prototype has been built where the output power fluctuation is within ±3.7% of the rated power, and the system efficiency (dc/dc) is higher than 88.5% with a 220 mm air gap.