An Accurate Automatic Phase Advance Adjustment of Brushless DC Motor

For improved efficiency and torque performance, brushless DC (BLDC) motors require a phase advance circuit. In a conventional phase advance circuit, the induced voltage of the Hall sensor is assumed to be a sinusoidal wave. But the actual induced voltage of the Hall sensor includes other harmonic components which influence the real phase advance angle. Performance curves of phase advance angle versus frequency for a conventional circuit do not work well when the harmonic components are considered. We therefore propose an improved circuit in which the phase advance angle is more accurate than that of a conventional circuit when the harmonic components are considered. Furthermore, the proposed circuit provides better performance. We present experimental results to verify the related theoretical analysis.