Abstract: The coupling coefficient of the loosely coupled transformer in the inductively coupled wireless

power transmission（ICPT）system is a key parameter affecting the conversion efficiency of the wireless energy

transmission system. To improve the coupling coefficient，an equivalent magnetic circuit model was established and analyzed based on the magnetic field simulation results of ordinary disc-shaped loosely coupled transformer. On this basis，the disc-shaped magnetic core was optimized by digging through holes and adding guide cores，and a new gear-shaped transformer structure was proposed combined with multi-U-shaped magnetic core structure.

Simulations and experiments verify that the structure can effectively increase the coupling coefficient of the

transformer while reducing the weight of the transformer，and has good rotation stability.

      Key words: inductively coupled wireless power transmission（ICPT）；loosely coupled transformer；magnetic

circuit model；gear-shaped magnetic core