A Half-Bridge CLC-Series Wireless Power Transfer System with Clamping Diodes

The LCL/LCC types of compensation networks are popular in wireless power transfer (WPT) applications. However, these types of topologies have certain disadvantages. The lack of input dc-blocking capacitor means that it cannot be driven directly by a half-bridge (particularly the LCL type of network). Furthermore, the input impedance of LCL/LCC types of networks would be zero if the primary coil is unconnected, which can lead to serious device failures unless additional protection measures are in place. By moving the resonant capacitor to the input, the CLC network can be obtained. The CLC network has certain advantages such as allowing the use of a half-bridge as well as allowing the addition of clamping diodes across split resonant capacitor for primary coil disconnection protection, soft-start and short-circuit protection. In this paper, the design equations and zero voltage switching (ZVS) criteria of the CLC-series network are analyzed. A 48-V, 45-W constant voltage output CLC-series WPT system is simulated and implemented to verify the proposed circuitry. Under different loads, the output voltage is shown to be well-regulated and the ZVS operation is achieved. The peak efficiency of the prototype WPT system reaches 90.9% under full load. The inherent protection features under primary coil disconnection and output overload and short-circuit conditions are verified with both simulation and experimental results.