Low-cost sensorless control of brushless DC motors using a frequency-independent phase shifter

This paper describes a sensorless control scheme for brushless DC motors (BLDCMs) using a phase shifter (FlPS) which can shift the zero-crossing point of the input signal with a specified amount of phase. The detection performance of the proposed FIPS is independent of the frequency of the input signal and quite robust with respect to the measurement noise. It is shown that the proposed sensorless control scheme using the FIPS is more effective in the respects of noise-robustness and cost than the previously known schemes. Moreover, a flux-weakening control scheme can be easily incorporated into the proposed sensorless control scheme. The generality and practicality of the proposed sensorless control scheme is demonstrated through performance analysis and experiments under various operating conditions.