Abstract: 3D wound core transformer has a special symmetry structure for three phase. It has several advantages, such as low core loss, light weight and better heat dissipation effect. Due to the structure of the core as well as the nonlinear magnetization of the silicon steel sheet, the magnetic field in the core has stronger 3rd harmonic waves, which make every frame of the core in non-sinusoidal excitation condition. Therefore it is impossible to measure the core loss of the frame of 3D wound core directly. In this paper three-dimensional finite element analysis model was established to analyze the distribution characters of 3D wound core. On this basis, non-sinusoidal exciting voltages of 3D wound core were measured, and a rapid test method of single frame core loss of 3D wound core was proposed and its availability was verified.

Key words: 3D wound core, non-sinusoidal excitation, silicon steel, core loss