Development of nanocrystalline Mn–Zn ferrites for forward type DC–DC converter for switching mode power supplies

摘要

Nanocrystalline Mn–Zn ferrites have been successfully synthesised using the microwavenhydrothermal method for high frequency applications. The nanopowders were characterised usingnX-ray diffraction (XRD) and transmission electron microscopy (TEM). They were annealed using thnmicrowave sintering method at 900uC for 20 min. The frequency dependence of the dielectrinconstant e9 and and the initial permeability minwere measured in the range 10 Hz to 1?3 GHz. Thnsaturation magnetisation Ms and coercive force Hc were obtained using a vibration samplnmagnetometer (VSM) in the field of 20 kOe. The total power loss was measured in the range on100 kHz to 1 MHz with a flux density of 50 mT on the annealed samples. Conductor-embeddednferrite transformers were fabricated and the output power Po and efficiency g were measured; 80%nefficiency was obtained for a forward-type multilayered transformer.