Shoorangiz Shams Shamsabad Farahani - Department of Electrical Engineering, Young Researchers and Elite Club, Islamshahr branch, Islamic Azad University, Islamshahr, Iran.
Alireza Siadatan - Department of Electrical Engineering, College of Technical and Engineering, West Tehran Branch, Islamic Azad University, Tehran, Iran. Visiting Professor, Energy Systems Group, The Edward S. Rogers Sr. Department of Electrical and Computer

Brushless DC motors face many challenges and complexities which could be considered as sensor-based or sensorless schemes for detecting the position of the rotor, and end in a variety of results. A brushless DC motor sensorless control system is developed in this paper and a sensorless technique which is based on a hysteresis comparator and a potential start-up method with a high starting torque has been suggested. In addition, the phase delay of the back EMFs, in case of passing low-pass filters, could be compensated by the hysteresis comparator which prevents multiple output transitions from ripple or noise in the terminal voltage. The rotor position is aligned at standstill for maximum starting torque without additional sensors and motor parameter information. Where, by modulating the pulse width of the switching devices during alignment, the stator current could be easily adjusted. In this paper, the simulation and the experimental results has been provided for validating the proposed method.

Brushless DC Motor (BLDC), Hysteresis Comparator, Sensorless control, Start-Up Technique