I. Research and Development Background

　　

　　Rectifiers and inverters are needed in solar power generation equipment and hybrid electric vehicles, and reactor is an indispensable component in rectifiers and inverters. Due to the need to withstand tens to hundreds of amperes of current, rectifiers and inverters must be large capacity, which puts forward higher requirements for reactors. Based on the above background, a new type of reactor core material has been developed by Japanese company diamet.

　　

　　II. Material Properties

　　

　　The core material of reactor mainly includes ferrite, pressed powder core, silicon steel plate, amorphous material and so on. Among them, although the saturated magnetic induction strength of the traditional compacted core is relatively high, but the efficiency is not high. The new compacted core material developed in this research is a new compacted core. In the compacted iron core, the newly developed ultra-thin, high heat-resistant magnesium oxide insulating film with a thickness of only tens of nanometers was applied to insulate the powder surface and between the powders, effectively improving the duty cycle of the material, i.e. filling factor, and thus improving the efficiency of the material.

　　

　　In addition, pure iron powder with high saturated magnetic induction and excellent compressibility is used as the powder material of compacted iron core, which can ensure the resistance characteristics of the core. Fig. 1 shows the saturated magnetic induction strength of newly developed compacted iron core compared with other materials. After completion of the research and development, it is confirmed that in the case of frequency greater than 10 kHz, the efficiency and silicon content of the compacted iron core are tested at 6.5%, and the results are shown in Fig. 2. As can be seen from Figure 2, with the increase of current, the performance of compacted iron core is obviously better than that of silicon steel plate.

　　

　　The volume of three-dimensional core made of newly developed compacted powder core can be reduced by 20%. Under the same parameters of rated current 4A and inductance 4mH, the volume of three-dimensional ferrite is 641 cm3, the volume of silicon steel plate is 223 cm3 with 6.5% silicon content, and the volume of amorphous material is 205 cm3. The volume of three-dimensional core made of newly developed compacted powder core is only 125 cm3. At present, this newly developed reactor core material is gradually improving and commercializing.