Abstract: Recent years，omni-directional wireless power transmission（WPT）technology has attracted more

and more attention as a solution to the limitations of free location and mobility of traditional WPT technology.

However，omni-directional WPT is less efficient due to low mutual inductance relative to the transmitter size.

Therefore，an optimized magnetic structure was proposed to improve the transmission efficiency of the transmitter

without increasing the size of the transmitter. Four candidate magnetic structures（sphere，cube，cross bar and threeorthogonal plane magnetic core）were presented，and their performances were compared using finite element analysis software. The Pareto optimal set was selected by multi-objective optimization design，and the optimal magnetic structure was determined by considering the weight of objective variables and Chebyshev distance. The optimal magnetic structure and omni-directionalWPT prototype were built，and the performance verification was carried out.The experimental results and simulation results show that the optimized magnetic structure can improve the transmission efficiency of the system in three-dimensional space. When the transmission distance is 150 mm，the systemefficiency can be improved by 18.6%.

      Key words: omni-directional wireless power transmission（WPT）；inductive power transfer；optimization design