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Application of Mn-Zn Ferrite in Permanent Magnet Brushless DC Motor with High Speed

In this paper, the application of Mn-Zn ferrite in permanent brushless DC motor (BLDCM) with high speed is introduced. Comparing with the materials commonly used in motors, Mn-Zn ferrite has many advantages, such as low specific weight, low iron loss, low magnetic permeability, low cost and so on. For that, Mn-Zn ferrite material's properties including magnetic flux density, magnetic field intensity, iron power loss vs. temperature are analyzed, based on which the appropriate operating temperature is selected. Some parameters such as leakage coefficient and iron loss are also calculated. Then, a motor model based on Ansoft software is built to verify the assumption of the impacts of Mn-Zn ferrite on the magnetic properties. Besides, a motor with 50W/25000rpm is analyzed and optimized with the aim of reducing torque ripple. Furthermore, a field-circuit combined model is constructed in Matlab/Simulink to analyze the working characteristics and motor efficiency.