Hybrid LCL LC compensated four plate capacitive power transfer for high power wireless electric vehicle charging

Recently, Capacitive Power Transfer (CPT) has been developed as a potential replacement for inductive WPT and attracted significant attention, especially as applications in Electric Vehicles (EVs), because of its lightweight coupler structure, low magnetic shield requirement and immunity to metallic environments. Nevertheless, it is still challenging to realise high power transfer efficiency and stable output characteristics over a large load and coupling variations in megahertz operating frequency. A hybrid LCL–LC compensated four-plate CPT system for high-power wireless EV charging applications is presented in this paper. The proposed topology uses an LCL compensation network at the transmitter for current-source operation and harmonic suppression, via an LC Compensation Network (LCN) on the receiver side, which provides Constant-Voltage (CV) output regulation. A full analytical model, based on the First Harmonic Approximation (FHA), is presented to obtain output voltage, power characteristics, reflected impedance and zero-phase-angle operation conditions. Analytical expressions for the equivalent self-capacitances and mutual capacitance of the four-plate coupler are derived, emphasising that it is intentional cross-coupling which contributes to improving the power transfer capacity. A systematic design procedure is developed to guarantee the resonant nature of operation, close to Zero-Phase-Angle (ZPA) input impedance and soft-switching characteristics. Simulation and experiment at 2 MHz show that the new circuit yields 1.3 kW of output power with a peak efficiency of 93.8%, demonstrating high energy efficiency under the rated conditions (270 V input, 15 cm air-gap, nominal alignment, and load range of 60–100 Ω). Furthermore, the system maintains efficiency above 76% under worst-case coupling conditions, corresponding to lateral misalignment up to 30 cm and air-gap variation from 15 cm to 25 cm. These results confirm that the proposed hybrid LCL–LC compensated CPT system is a robust and efficient solution for practical high-power wireless EV charging applications.