For wireless power transferred (WPT) system with multi-receiver, the cross coupling effect between non-adjacent coils may seriously impact the performance of the system, decreasing the transferred power and the efficiency. In this paper, a theoretical analysis on the transferred power and the efficiency of two kinds of WPT system models with two-receiver is proposed via circuit theory. Furthermore, a reactance compensatory method is proposed to eliminate the adverse effect brought about by cross coupling, as well as a performance evaluated method introduced for comparing the transferred power and the efficiency before and after compensation. Numerical simulations and experimental results show the transferred power and the performance score are increased remarkably after compensationand it verifies the feasibility of this compensatory method.

For wireless power transfer (WPT) application with multi-load or multi-repeater, the system must need some inductance coil possessing the characteristic of transmitting power to multiple directions. This paper proposes a novel three-dimensional hexagon coil with simple structure, which is fabricated conveniently and easy to conformal with surrounding environment. The formula to calculate self-and mutual-inductances for the coil are given with the direction feature also introduced. Furthermore, numerical simulations and experimental results show mutual inductance is very stable in a wide scope of direction angle, to be applied in WPT with multidirectional transmission characteristics.

The use of multi-resonators for medium-range wireless power transfer (WPT) systems is an important concern; the cross-couplings between non-adjacent coils have an adversely impact on the transmission distance and efficiency of the system. This paper proposes a dumbbell-shaped (DS) coil in a WPT system. The DS coil structure was analyzed theoretically and verified experimentally. The proposed scheme eliminates cross-couplings between non-adjacent coils in the multiple resonator system to resolve frequency drift, and improve the transmission distance and efficiency in the multiple resonator system. The scheme features a coplanar structure which can secure direct-coupling and save space when applied in the home, office, and public areas.

Charging mobile electronic devices is a hot topic in the field of wireless power transfer. The change of mutual inductance during the movement of the electronic device will cause the output voltage to fluctuate and the power transfer efficiency to drop. In order to solve these problems, this paper proposes a CLC compensation network that is embedded between the power supply and each transmitter coil. Optimizing the parameters of the CLC compensation networks can ensure that the position-varying load obtains stable voltage while ensuring high power transfer efficiency. Specific theoretical analysis of output voltage control and power transmission efficiency optimization is detailed in the article. Finally, a typical experimental platform is established and the result of the experiment can verify the theory.