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This paper presents a novel back-electromotive-force (EMF) detection method for sensorless brushless DC (BLDC) motor drive systems. By this method, a true back-EMF signal can be directly extracted for each phase without sensing the neutral point of the motor. The method proposed is not sensitive to switching noise and requires no filtering. Good motor performance is achieved over a wide speed range as well. This novel sensing scheme is implemented into a hardware macro cell inside a mixed-signal microcontroller. The proposed microcontroller-based sensorless BLDC drive system has been successfully applied to automotive fuel-pump applications, which require high reliability and intelligence at a low cost.
Date of Publication: Nov.-Dec. 2003