Load-Independent Voltage Control for Multiple-Receiver Inductive Power Transfer Systems

This paper proposes a multiple-receiver inductive power transfer platform which is capable of controlling the load voltages to satisfy individually rated values and stabilizing the load voltages against the load variations. In the proposed charging platform, multiple transmitting resonators are employed to support a voltage-driven source resonator in manipulating the energy flows toward individual receivers. This structure also helps the voltage source induce constant currents into the transmitting resonators, and therefore, is able to deliver load-independent voltages to the loads. As a result, when the loads are sufficiently large, the load voltage ratio is approximately determined only by the mutual couplings of the coils. This means that the voltage control can be performed by effortlessly adjusting the arrangement of the transmitting resonators inside the charging platform. Electromagnetic simulation and experiment results verify voltage stability and controllability of the proposed system. Although typical constant voltage designs inevitably suffer from efficiency degradation, our scheme can achieve an efficiency of up to 56°, which is acceptable and sufficient for many practical applications.