Abstract: 12 slot with 8 pole built-in permanent magnet BLDC motor as the research object, the key technology for rotor eccentric rotor, permanent magnet magnetic field intensity fluctuation manufacturing side of the impact of electromagnetic noise problem, based on finite element electromagnetic simulation, different computing process variation of the rotor in motor electromagnetic vibration and noise, finally qualitative quantitative analysis of the rotor effect and process of electromagnetic noise. The static eccentricity of rotor should be controlled within 10%, the dynamic eccentricity should be controlled within 10%, and the fluctuation of magnetic field intensity of permanent magnet should be controlled within 2%.

Key words: BLDC motor, The rotor eccentricity, The magnetic field strength of permanent magnet fluctuates, Electromagnetic noise