Phase and intensity control of multiple coil currents in mid-range wireless power transfer

Many studies have attempted to increase the transmission distance for wireless power transfer, particularly since the development of resonant magnetic coupling. As a result, wireless power transfer is now possible in mid-ranges, but it has led to new problems, such as device posture-related problems. In wireless power transfer using magnetic fields, adequate efficiency is difficult to obtain when the receiver coil is parallel to the magnetic field, and such cases easily occur. To solve this problem, the authors propose a method to control the phase and the intensity of multiple coil currents by considering the power source. They developed a simulation model and investigated a suitable control method for two assumed applications. They developed two control methods, one for a portable device and the other for the sensors. By performing numerical simulations and experiments, they confirmed that the methods produced the desired effects.