Speed Control for Four Quadrant Operation of Three Phase Bldc Motor Using Digital Controller

Abstract

This paper proposes a method that estimates rotor position by using an unknown input observer over a full speed range. In this method, a trapezoidal back emf is modeled as an unknown input and the proposed unknown input observer estimating line to line back emf in real time makes it possible to detect the rotor position. This observer has high performance even at low speed range because rotor position is calculated independently of the rotor speed without adding any additional circuit or complicated operation process. Simulations have been carried out for the verification of proposed control scheme. MAT LAB/SIMULINK model is used for software simulation. Keywords-BLDC motor, Four quadrant operation, sensorless control, full speed range, unknown input observer.