Sensorless Operation Of Permanent Magnet Brushless Dc Motor Based On Infinite Impulse Response Digital Filter
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Date
2010-10
Authors
Faeq, Maher
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
This dissertation presents a new sensorless operation for permanent magnet brushless
DC motor based on digital filtering of back-EMF waveform using dsPIC30F6010
microcontroller. In motor drives, PWM technique is normally used to vary the voltage
imposed on the motor terminals, and therefore controlling the speed of the motor.
Generally, the back-EMF signal of the un-energized phase winding has noise imparted
from the driven motor phases. However, it is relatively difficult to detect the zerocrossing
event of the back-EMF waveform due to the coupled PWM noise. With
appropriate approach, a filtered back-EMF signal can be generated from the measured
waveform which looks more like an ideal signal. Thus, the process of detecting zerocrossing
event will be more successful. A theoretical basis is first developed and
presented, considering the electrical and mechanical dynamic aspects of the permanent
magnet brushless machine in Matlab Simulink model with traditional PI speed
controller. Two simulation models for sensor and sensorless operations respectively are
first performed with digital filtering step on the terminal voltage signals and their results
are discussed. Also given are details spectrums of the back-EMF waveforms embedded
with PWM chopping as computed by Fast Fourier Transform. Analyzing the spectrums
further could lead to appropriate design of an optimal low digital filter required. Varying
structures and practical implementation of infinite impulse response (IIR) digital filter
has been examined and considered.
Description
Keywords
Permanent Magnet Brushless Dc Motor , Infinite Impulse Response