A new power MnZn ferrite for broad temperature range applications

The present study focuses on the targeted compositional and process design towards the development of a new MnZn ferrite material for high-efficiency power conversion systems that exhibits very low power losses at low frequencies across a broad temperature range extending from 25°C to 160°C. The MnZn ferrite powders were prepared by solid state processing, while the compositional design involved the investigation of several Co-doping levels (0 to 6000 ppm CoO) on the basic composition. Analysis of the contributions of hysteresis and eddy current power loss mechanisms to the overall power losses led to the design of further steps, targeting to the limitation of the chemical, morphological and microstructural defects, along with optimization of dopants distribution, through processing. This was achieved by the introduction of a primary heat treatment of the raw materials mixture and an optimization of the particle size distribution, both steps applied before the standard process of solid state reaction, resulting to an overall reduction of the power losses across the temperature range from 25 to 160°C. The developed MnZn ferrite material exhibits an initial permeability of 3200 at 10 kHz, 0.1 mT, 25°C, power losses <300 mW/cm3 at 100 kHz, 200 mT from 25 to 100°C and a superior magnetic performance at high temperatures, exhibiting the lowest reported power losses of 380 mW/cm3 at 100 kHz, 200 mT, 160°C, making it suitable for high energy-efficient products, independent of the environmental temperature and loading of the transformer.