A Commutation Optimization Strategy for High Speed Brushless DC Drives with Inaccurate Rotor Position Signals

The control performance of Hall sensor based high speed brushless DC (BLDC) motor drives depends heavily on the accuracy of Hall sensor signals. Due to the existence of Hall signal errors, the system may operate under unbalanced conditions which will lead to asymmetric currents and high torque ripple. For high speed drive, the pulse-width modulation (PWM) update delay will also lead to inaccurate commutation. In this paper, two Hall signal errors, i.e., misaligned and uneven Hall signal errors, are investigated and a Hall signal balancing strategy is developed to detect Hall signal errors and regenerate balanced Hall signals. A new PWM generation scheme is then proposed to eliminate the PWM update delay. Both simulation and experiment results have verified the effectiveness of the proposed strategy.