A Multi-Load Capacitive Power Relay System With Load-Independent Constant Current Outputs

This article proposes a power relay system to wirelessly power multiple loads via capacitive coupling. The intermediate capacitive relay unit is designed to power the load as well as enhance the power transfer capability, which contains two receiving plates and two transmitting plates. It is proven in this article that the capacitive coupling between the receiving and transmitting plates in the same relay unit can be eliminated by being placed perpendicularly with the help of the proposed split-inductor-based compensation network. A general mathematical model of the multiload capacitive power relay system is established. The L compensation circuits are employed to compensate the first and the last relays, while the LCL compensation circuits are designed to compensate the intermediate relays. Thus, the constant current output can be obtained for each load without affecting each other when neglecting the parasitic resistances. Additionally, the load current and efficiency variations versus the load resistance, coupling coefficient, and quality factor are thoroughly analyzed. Finally, a three-load experimental prototype is constructed to verify the feasibility of the proposed multiload capacitive power transfer relay system. The maximum efficiency can reach 86.1% at a power level of 37 W.