Improved Angular Displacement Estimation Based on Hall-Effect Sensors for Driving a Brushless Permanent-Magnet Motor

We propose an improved method for angular displacement estimation based on Hall-effect sensors for driving a brushless permanent-magnet (PM) motor. The control current with an angle that leads the back electromotive force is then determined to extend the speed range of the motor. Traditionally, Hall-effect signals are measured by both the capture interrupt and periodic timer interrupt functions before the angular displacement is precisely estimated with a digital signal processor. Unfortunately, the capture interrupt function is highly sensitive to external noise. The proposed method retains the periodic timer interrupt function and simplifies the estimation operation, so that the controller is robust to external disturbances. We used the improved method to adjust the phase lead angle for driving both a surface-mounted-PM motor and an interior-PM synchronous motor. Experimental results show that the improved angular displacement estimation effectively rejects noise and is 2.9 times faster than the traditional approach.