A Starting Method of Brushless DC Motor for Rotor Position Sensorless Control Using a Magnetic Field Stator Winding Excited Technique

Abstract

This paper presents a starting method of a 100W, 30V. 4500rpm Brushless DC (BLOC) motor with

Surface Permanent Magnets (SPM) for rotor position sensorless control using a magnetic field stator winding

excited technique. This technique helps starting of the brushless DC motor resulting in identifying the initial

rotor position by exciting phase winding. After that. the motor is controlled in open loop operation w1th a 120

degree rectangular wave technique in order to generate back electromotive force (back-EMF). The back-EMF

is monitored by using zero crossing. The rotor position and speed are calculated from the relation between

back-EMF and zero crossing periods. Then. the motor is driven in closed loop speed control. Additionally,

cons1dering magnetic flux distribution resulting from the proposed initial stator excitation is given using 2-D

Finite Element Analysis (2-0 FEA) by the SPEED software package. The overall control system is processed by a 16 bit dsPIC which is a Digital Signal Controller (DSC).