Download Faculty of Electrical Engineering Three phase permanent magnet

Faculty of Electrical Engineering
Three phase permanent magnet
brushless DC motor Controller
Student: Mohd Syafiq Bin Mohd
Supervisor: Dr. Abdul Rashid Husain
reference speed. The actual speeds that will be
used as feedback for this system can be obtained
by manipulate the hall sensor signal. The internal
timer in PIC and external interrupt can be used for
measuring the speed of a PMBLDC motor. The
pole pair numbers is one of the parameter that will
determine the actual speed of BLDC motor. This
actual speed can be display by using LCD display
and the speed data is transferred serially to the
PC by using RS232. For interfacing purpose
which is to receive the speed data from PIC, a
special GUI has been developed based on Visual
Basic.
INTRODUCTION
Permanent magnet brushless DC (PMBLDC)
motors have been used in many applications due
to their high efficiency, silent operation, compact
size, high reliability and low maintenance
requirements [1]. The operation of PMBLDC is
based on electronic commutation where it
requires a drive unit, which consists of inverter
and driver, positioning sensor for sensored type
drive and a microcontroller controlling the step of
commutation. Precise commutation steps is
crucial in order to achieve reliable speed and
radial displacement control which make the
control of PMBLDC remain crucial in many
applications.
RESULT AND ACHIEVEMENT
Figure 1a shows the circuitry of the control
system where it contains the six FB180SA10
HEXFET power mosfet that serves as the
switched and hall effect sensor for obtaining the
feedback signal, while figure 1b shows the
PMBLDC motor with the mounting. It has been
shown in this work that both the open- and
closed-loop control of PMBLDC is achieved with
good speed control.
PROJECT OBJECTIVES
The aim of this project is to develop a prototype
of three phase PMBLDC motor controller based
on electronic commutation system open- and
closed-loop control tecniques. Hall effect sensor
will be used to obtain the commutation signals
where it will be used as the feedback signal in
performing the closed-loop control on the system.
The measurement of the sensor will also be
displayed online for verification of the value used
in the controller.
METHODOLOGIES
The basic principle of controlling the PMBLDC is
to produce the correct commutation pulse such
that the rotor of the motor can be rotated at
desired angle based on stator axis as the
reference. The sequence analysis can be used in
order to get the commutation sequence by
analyzing hall sensor and phase current signals.
The speed of BLDC can be controlled by varying
the average voltage or current that passes
through the motor. This average voltage can be
controlled by adjusting the duty cycle of the PWM.
For open loop speed control, the desired speed
can be utilized by using potentiometer that is
connected to analog to digital. The output from
the ADC will be feed to the duty cycle register.
For closed loop speed control, the ADC value
from potentiometer will be used to get the
(a)
(a)
(b)
Figure 1: Control system of PMBLDC
REFERENCE
[1] T. Kenjo & S. Nagamori, Pemanent Magnet
and Brushless DC motor, Clarendon Press,
Oxford, 2005.
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