LLC resonant converter for wireless energy transmission system with PLL control

This paper presents a wireless transcutaneous energy transmission system utilizing the magnetic coupling of coils. No physical wire connection is required between the circuits inside and outside the body. Because the transformer is the contactless transformer, the coupling efficient of the transformer is not good as normal transformer. The parameter of the leakage inductance of transformer will be larger than the magnetizing inductance of transformer. An LLC resonant converter is used outside the body. The LLC resonant converter could have higher power conversion efficiency to improve wireless transcutaneous energy transmission system efficiency. In addition, the soft-switching structure of a LLC resonant converter is utilized. A phase locked loop is adopted to control the LCC resonance to facilitate the steady electrical energy transfer. According to the experimental results, the system can deliver an output power around 1W to the load circuits inside the body and the output voltage can be regulated at 4V.