Magnetic field coupling wireless power supply technology, which enables power transmission without a charging cable, is attracting attention as a new technology to diffuse advanced medical technologies, such as those for power supply to capsule endoscopes, artificial organs and other internal medical devices.
 However, the magnetic field coupling wireless power supply system, which uses resonance phenomenon, has a disadvantage in that if the resonance frequency shifts due to variations in the properties of the device during manufacturing, during aging, or in the operating environment, the transmittable power can change significantly. Without a solution to this problem, application to medical devices will be impossible.
 The objective of this research is to enable stable power transmission in any environment by actively controlling the resonance phenomenon using switching circuit technology. We have already succeeded in a demonstration test using a prototype testing machine and are now working on practical application.