Design of Wireless Power Transfer System for Low-Speed Vehicles Based on LCC-S Topology

With the development and application of wireless power transmission (WPT) technology, the value of WPT technology in practical applications is being recognized. According to the actual application requirements of low-speed vehicles and the WPT realization of passenger cars, this paper studies the WPT scheme suitable for low-speed vehicles. For the constant-voltage battery load, a scheme is proposed that the load battery is directly connected to an uncontrolled rectifier and the output power is controlled on the transmitting side through communication. Due to its constant-voltage-output feature, the LCC-S topology is used as the compensation network, which can realize mutual-inductance estimation and auxiliary power supply at the same time. The mutual-inductance estimation formula based on DC voltages is given, which reduces the sampling difficulty and still ensures that the detection accuracy meets the requirement of coil alignment. A 3.3-kW wireless charging prototype was built, the output voltage ranged from 48 to 75V and the max output current reached 60A. The power, efficiency, and mutual-inductance estimation were tested under different coupling and load voltages. The results show that the overall efficiency of the low-voltage large-current system is higher than 85% and the maximum efficiency reaches 88.4%, which verifies the feasibility of the proposed scheme.