An LCC-S compensated wireless power transfer system using receiver-side switched-controlled capacitor combined semi-active rectifier for constant voltage charging with misalignment tolerance

The output characteristics of wireless power transfer systems are strongly susceptible to coupling and load variations. To achieve a constant voltage output under varying coupling and load, a voltage regulation method based on a combination of a semi-active rectifier (SAR) and a switched-controlled capacitor (SCC) is proposed for the LCC-S topology. Adjusting the SAR can effectively regulate the voltage, and the introduction of SCC compensates the impedance brought by SAR, ensuring that the resonance condition is fully satisfied at the receiver side. Thus, the proposed wireless power transfer system can achieve zero phase angle over the entire load and coupling range, minimizing reactive power losses. This control method only needs to collect the signal from the receiver side, which enables single-side control as well as avoids the wireless communication. The situation of coupler parameter drift due to misalignment is also considered. Even if the self-inductance changes, the zero phase angle can be guaranteed on the receiving side by adjusting the SCC, and the zero voltage switching of the transmitter side can still be achieved. The principle prototype of 3 kW is constructed and the experimental results prove the effectiveness of the proposed method.