Design and control of three-phase brushless sensorless DC motor

Abstract

Brushless DC (bldc ) motors are widely used in many application such as hard disk and CD drive, robots , fans and pumps… etc, this referred to their advantages that have it, such as simple construct, good performance , reliability and high speed. In this project we aim to study the construction and principles of operation of three phase brushless DC motor, design the excitation circuit (p.magnet rotor) and armature circuit, replace the mechanical position sensor with EMF electronic circuit applied the pc as controlling unit of the motor, and finally we aim to implement this design and compare with two phase (BLDCM) . The signal obtained from the tachogenerator is processed by an 8085 microprocessor-based system through an A/D converter . the 8085 microprocessor is the main control device (controller). It contains the comparison circuit of the closed loop system.