Starting of BLDC Motor Without Position Sensors

Abstract

This paper discusses about finding of initial rotor position when motor is not yet started or motor is stand still. The main or key point of finding initial rotor position is by simple detection and voltage comparison of each phase & responses of current which is related with the stator inductance variation. In the proposed method 3 voltages-pulse are injected and we achieved a resolution of 30ο.The method effectives is verified by using simulation. In extension of this we derived an equation for initial rotor position. Which depends on the currents of each phase.