Multiple-load wireless power transmission system through time-division multiplexed resonators

This paper presents a wireless power transmission system which is able to deliver power to multiple loads by making use of a time-division multiplexing technique. Similar loads are placed into the slots in a row, and two power transmitters, at the bottom and top, supply them with sufficient amount of power. This system operates in two phases; within one phase, the transmitters are in-phase, and the resonators placed in odd slots are unloaded and act as power repeaters, and the resonators placed in even slots receive power. In the other phase, the transmitters are out-of-phase, and the resonators placed in odd slots receive power while others behave as repeaters. An optimization process is developed in order to find the optimum number of loads so that the required voltage is provided for each load while the headroom voltage of the transmitters does not increase considerably. An optimized seven-load system is implemented for powering 82-Ω loads with 2 W. Experimental results show that at least rectified voltage of 4.3 V is provided for each load, which is enough for typical lithium-ion battery chargers.