High-Power Field-Focusing Circuit for Dynamic Wireless Power Transfer Systems

Abstract

This paper proposes a field-focusing dynamic wireless power transfer (DWPT) system and presents a design and sensitivity analysis of the system. The proposed system utilizes a reflected impedance to allow a single inverter to drive multiple transmitter coils. The approach can achieve high currents with field focusing only in the transmitter coil that is presently coupled to a receiver coil as a vehicle travels along a DWPT roadway system, while the remaining coils connected to the shared inverter operate with significantly lower current. The benefit of this approach is that it can reduce the number of inverters and receiver position sensors required in DWPT systems. The proposed circuit topology also achieves higher output power than the conventional circuit through the use of the proposed additional compensation components. Theoretical analysis, design, and sensitivity analysis are conducted to compare the conventional and proposed field-focusing circuit. The design results show that the maximum output power of the proposed circuit is 102% higher than the conventional circuit. The sensitivity analysis results show that the additional compensation components in the proposed circuit can work well to increase the output power and current gain simultaneously. A 2kW DWPT prototype of the proposed circuit with a 250 mm gap is constructed according to the designed circuit parameters. The experimental results show that the prototype matches well with the simulation results and that the circuit magnifies the transmitter coil current 2.5 times higher for the coil in the coupled condition compared to the coils in the uncoupled condition.