17-01-2013, 03:37 PM
COMPARATIVE STUDY OF AXIAL FLUX PERMANENT MAGNET BRUSHLESS DC MOTOR OPERATING WITH THE WINDING CONNECTED IN SINGLE-PHASE AND TWO-PHASE SYSTEM
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ABSTRACT
The object of the study is a double-sided axial flux permanent magnet brushless
dc (AFPM BLDC) motor with salient pole stator. Its winding can be connected either in
single-phase or in two-phase system, which results in different operation of the motor
The objective of the thesis is to analyze and compare the performances of the
AFPM BLDC motor with single-phase winding and two-phase winding. To study the
motor operation, a mathematical dynamic model has been proposed for each of the motor
with different winding, which became the basis for simulations that were performed
using MATLAB/SIMULINK software package.
The calculations were done for the particular motor which was designed as a
water pump with the wet rotor. The results of simulations were presented in form of the
waveforms of selected quantities and the electromechanical characteristics performed by
the motor in steady-state conditions. The later were the basis for developing a simple
mathematical model of the motors which allow to analyze their performance only in
steady-state conditions.
INTRODUCTION
Conventional DC motors are highly efficient, however, their only drawback is
that they need a commutator and brushes which are subject to wear and require
maintenance. The above mentioned deficiency of the conventional solution can be
overcome by the new type of DC drive based on brushless DC motors operating without
mechanical transmission [1].
The brushless DC motors (Figure. 1.1) are permanent magnet motors where the
functions of commutator and brushes were implemented by solid state switches [2]. The
brushless DC motors are distinguished not only by the high efficiency but also by their no
maintenance. The permanent magnet motors used in this case are single phase or poly
phase motors. When operating with single phase or poly phase motors, the inverter plays
the role of the commutator. In this project single-phase and two-phase inverters are
considered.
Axial Flux Permanent Magnet Motor Structure
Double-sided AFPM motor with one stator, which is an object of this study, is
shown in Figure. 2.2 [8, 12]. It is more compact than the motor with internal rotor. The
double-sided rotor with PMs is located at the two sides of the stator. The stator consists
of the electromagnetic elements made of ferromagnetic cores and coils wound on them.
These elements are placed axially and uniformly distributed on the stator circumference
and glued together by means of synthetic resin.The particular motor with the dimensions
shown in Figure. 2.3 was designed as an integrated water pump [8].
CONCLUSIONS
The performances of the AFPM BLDC motor with single-phase and two-phase
winding were analyzed in this thesis. To study the motor operation, a mathematical
dynamic model has been proposed for both the cases. This model became the basis for
block diagram and simulations, which were performed using MATLAB/SIMULINK
software package.
The results obtained from the simulation in steady-state allowed to draw the
electromechanical characteristics, which illustrates the motor performance. These
characteristics were the basis for determination of the simpler motor model, which is
normally used to analyze the conventional brush DC machines.