The biggest advantage of ferrite soft magnetic is that it has high permeability and resistivity (102 ~ 106) at high frequency Ω· It once replaced iron powder core. However, its BS is much lower than that of metal materials, so it can only be used at low power. The magnetic powder core just fills the gap between metal soft magnetic material and ferrite. Generally, the frequency of use from low to high is metal, magnetic powder core and ferrite, and the power from low to high is ferrite, magnetic powder core and metal.
As a kind of multifunctional magnetic material, ferrite can make almost any inductive device. Strictly speaking, metal magnetic powder core can only be used to make inductive devices
(1) Metal magnetic powder core has high BS, low permeability and quasi linear bias curve, which can withstand larger DC bias.
(2) The uniform distribution of the air gap of the metal magnetic powder core can avoid the local loss caused by the open air gap.
(3) Metal magnetic powder core is more insensitive to environmental change (temperature change and mechanical impact) than ferrite, which is determined by the characteristics of metal and ceramic materials. The former has high Curie temperature and little change of permeability in working range, so its reliability is better than the latter. The working temperature range of metal magnetic powder core is wider than that of ferrite, and some materials can work at 300 ℃.
(4) The design method of metal magnetic powder core is relatively simple. When designing power choke, it is almost unnecessary to test the dynamic index to verify the design. Due to the poor material stability, ferrite needs to be designed differently according to different conditions, and needs to be tested dynamically.