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A Three-Phase Permanent Magnet Brushless DC Motor for Low-Power Low-Speed Fan Applications - Optimizing Cost and Efficiency

In this paper, a three-phase permanent-magnet brushless-DC motor is described with three-times the measured efficiency in the same frame size as compared to fan motors of conventional designs. The finite element (FE) analysis is performed to compare bonded NdFeB, ferrite and hybrid permanent magnets to optimize the cost and efficiency of the motor. Experimental results on a laboratory prototype verify the simulations. A novel design optimization procedure using Halbach magnetization is proposed to further increase the efficiency by shaping the back-EMF waveform. Based on FE analysis, efficiency gains of using Halbach-magnetization, in combination with 120-degree and 180-degree phase-current- conduction motors are compared.