High field properties of nickel-zinc ferrites at 1-10 MHz

The design of compact and efficient magnetic components for 1-10 MHz power conversion has been hindered by the lack of permeability and loss data for nickel-zinc ferrites. A technique for measuring permeability and loss density in magnetic materials at high-frequency and high-flux levels is described. Data is presented for eight commercially available nickel-zinc ferrites at 25 degrees C, operating at frequencies between 1 and 10 MHz, and at flux levels up to 300 G. Loss density was found to increase with frequency and flux level. High-loss density limits practical flux levels to less than 300 G. The higher permeability materials generally displayed higher loss. Indiana General Q1 ferrite was found to have the lowest loss in response to a purely AC excitation; DC offset increased loss density.<
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