Optimal Design of Heat Dissipation Structure and Experimental Verification of MFT Considering Insulation Performance

Although the increase in frequency improves the transmission efficiency of medium-frequency transformers (MFTs), the heating problems of MFTs are more serious than those of conventional power transformers due to the increase in core losses and winding losses. After testing the insulation properties of insulating materials at 1~20 kHz, the internal insulation structures of the medium frequency transformer (MFT) were designed to avoid breakdown or flashover occurring during long-term operation. Subsequently, heat dissipation methods were proposed for MFT models with different volume requirements. Finally, a natural air-cooled MFT prototype with the rated parameters of 200 kVA and 10 kHz was developed. The simulation results show that the natural air-cooling method with heat sink fins on the upper and lower sides can limit the temperature rise of MFT to the allowable range for a 200 kVA, 10kHz MFT. While if a smaller volume is required, the forced air-cooling method with an air velocity of 1.6 m/s needs to be used. Finally, the rationality of the above design was verified by the temperature rise test of the MFT prototype.