Design of Fuzzy Logic Controller for Speed Regulation of BLDC motor using MATLAB

IJSRD - International Journal for Scientific Research & Development| Vol. 1, Issue 2, 2013 | ISSN (online): 2321-0613
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Design of Fuzzy Logic Controller for Speed Regulation of BLDC motor
using MATLAB
1
Mr. Rakesh Makavana 2
Prof. B. A. Shah 3
Mrs. Dharmistha Makwana
1
PG student 2
Professor 3
Assistant Professor
1,2,3
Electrical Engineering Department
1,2
S.S.E.C., Bhavnagar, Gujarat, India
3
K.I.R.C, Kalol, Gujarat, India
Abstract— Brushless DC (BLDC) motors drives are one of
the electrical drives that are rapidly gaining popularity, due
to their high efficiency, good dynamic response and low
maintenance. The design and development of a BLDC
motor drive for commercial applications is presented. The
aim of paper is to design a simulation model of inverter fed
PMBLDC motor with Fuzzy logic controller. Fuzzy logic
controller is developed using fuzzy logic tool box which is
available in Matlab. FIS editor used to create .FIS file which
contains the Fuzzy Logic Membership function and Rule
base. And membership functions of desired output. After
creating .FIS file it is implemented in the Matlab Simulink.
And the BLDC motor is run satisfactorily using the Fuzzy
logic controller.
Keywords: BLDC, Fuzzy Logic Controller, Fuzzy tool box
I. INTRODUCTION
There are mainly two types of motor use in industries. One
of them is conventional DC motor where flux is produced
by current pass through field coil of stationary pole
structure. The second type of motor is Brushless DC motor
where the permanent magnet provides necessary air gap flux
instead of wire wound field poles. Conventionally BLDC
motor is also define as a Permanent Magnet Synchronous
Motor with Trapezoidal Back EMF. As is name is BLDC,
its do not use brushes for commutation, so it is electronically
commutated. In recent days, high performance BLDC motor
drives are widely used for variable speed drive system of the
industrial application and electrical vehicles.
Now days, to design drive for BLDC motor drive
involves few complex processes like Modeling, Control
scheme selection, implementation of control scheme,
simulate and tune the parameters to get desire outputs.
Recently, so many control strategies are introduced for
speed control of BLDC motor. However, most popular,
simple, stable, reliable controllers are PID controller. Now
days 95% of industrial drives are PID controller drive. Now
days, different industrial process having different parameter
with nonlinearity, variability and uncertainty of operation.
So, it’s difficult to modeled that process mathematically and
tune PID control parameters. Therefore it’s difficult to get
optimal output for that particular process.
Therefore, another control logic called Fuzzy Logic
is introduced instead of PID controller to BLDC motor
speed regulation system. Fuzzy controller regulates input
voltage of BLDC motor in real-time. To achieve smooth and
quick control, number of inputs as well as no. of
membership functions must be increased. At the same time
the individual set of rules are formed for each input. By
using individual set of rule, controller controls the input
voltage of the BLDC motor.
The main Aim of papers is to show a dynamic
response of speed with Fuzzy Logic controller to control the
speed of motor to keep motor running at constant speed
when load is very. The simulation results show that
performance of Fuzzy controller has better performance than
conventional PI controller.
II. BASIC STRUCTURE OF SPEED CONTROLL
SYSTEM OF BLDC
The block diagram of speed control of three phase BLDC
Motor is below Fig. 1. There are main two control loops are
used to control BLDC motor. The inner loop provides
synchronize the inverter gates signals with the EMF. The
outer loop controls the motor's speed by varying the DC bus
voltage.
Driving circuitry consists of three phase power
convertors, which utilize six power transistors to energize
two BLDC motor phases concurrently. The rotor position,
which determines the switching sequence of the MOSFET
transistors, is detected by means of 3 Hall sensors mounted
on the stator. By using Hall sensor information and the sign
of reference current (produced by Reference current
generator), Decoder block generates signal vector of back
EMF. The basic idea of running motor in opposite direction
is by giving opposite current. Based on that, we have Table I
for calculating back EMF for Clockwise of motion and the
gate logic to transform electromagnetic forces to the 6 signal
on the gates is given Table II.
INVERTER
HALL EFFECT
SENSOR
FUZZY LOGIC
CONTROLLER
BLDC
MOTOR
SUPPLY TO
MOTOR
TRIGERING PULSE SPEED
MEASUREMENT
µr
µm
OUTER LOOP
INNER LOOP
Fig.1: Block Diagram of speed control of BLDC Motor
Hall
sensor
A
Hall
sensor
B
Hall
sensor
c
EMF
A EMF B
EMF
C
0 0 0 0 0 0
0 0 1 0 -1 1
0 1 0 -1 1 0

Design of Fuzzy Logic Controller for Speed Regulation of BLDC motor using MATLAB
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392
0 1 1 -1 0 1
1 0 0 1 0 -1
1 0 1 1 -1 0
1 1 0 0 1 -1
1 1 1 0 0 0
Table. 1: Clockwise Rotation
EMF
A
EMF
B
EMF
C
Q1 Q2 Q3 Q4 Q5 Q6
0 0 0 0 0 0 0 0 0
0 -1 1 0 0 0 1 1 0
-1 1 0 0 1 1 0 0 0
-1 0 1 0 1 0 0 1 0
1 0 -1 1 0 0 0 0 1
1 -1 0 1 0 0 1 0 0
0 1 -1 0 0 1 0 0 1
0 0 0 0 0 0 0 0 0
Table. 2: Gate Logic
III. DESIGN OF FUZZY LOGIC CONTROLLER FOR
BLDC
Fuzzy logic’s linguistic terms are most often expressed in
the form of logical implications, such as If-Then rules.
These rules define a range of values known as fuzzy
membership functions. Fuzzy membership functions may be
in the form of triangle, a trapezoid; a bell .In figure 2 fuzzy
controller calculates an "error" value as the difference
between reference speed and actual speed.
Fig.2: Membership functions of fuzzy controller
Seven membership function has used, functions
defined as: Negative Big (NB), Negative Medium (NM),
Negative Small (NS), Zero (Z), Positive Small (PS), Positive
Medium (PM), and Positive Big (PB) given 49 rules in
Table III.
The min-max compositional rule of inference and
the center-of-gravity method have been used in defuzzifier
process.
If input 1 is NB and input 2 is NB Then u is PB,
If e1 is NB and e2 is NM Then u is PB,
If e1 is NB and e2 is NS Then u is PM,
If e1 is NB and e2 is Z Then u is PM,
…………………………………………
And go on for all inputs.
Input 1: Input 2 : Derivative of Error
Error NB NM NS Z PS PM PB
NB PB PB PM PM PS PS Z
NM PB PM PM PS PS Z NS
NS PM PM PS PS Z NS NS
Z PM PS PS Z NS NS NM
PS PS PS Z NS NS NM NM
PM PS Z NS NS NM NM NB
PB Z NS NS NM NM NB NB
Table. 3: Fuzzy Rule Table
MATLAB/Fuzzy Logic Toolbox is used to simulate FLC
which can be integrated into simulations with Simulink. The
FLC designed through the FIS editor is transferred to
Matlab-Workspace by the command “Export to file”. Then,
we have FIS file which is used in Simulink block name
Fuzzy Logic Controller. We have to specify the file name in
that block and put file into same path of model file. Fig.6.10
Shows the Matlab model of Implementing Fuzzy logic
Controller for BLDC motor.
Fig.3: FIS Editor for Creating FIS file
Fig.4: Membership Function Plot for Input-1

393
Fig.5: Membership Function Plot for Input-2
Fig.6: Membership Function Plot for Output
In FIS editor, after defining all input and Output. We have to
specify the rule base for that. In our case we have 49 rules to
define. After that we export .fis file.
Fig. shows result for input1 & input2 are zero. And
same time calculated output if 488.
Fig.7: Rule base view of all 49 rules.
IV. SIMULATION
The computer simulation runs such that the speed of the
BLDC motor remains at 3000 rpm (reference speed) in the
steady state, with load of 3 N.m. This constraint is provided
by means of the fuzzy logic controller. Error is calculated by
subtracting the reference speed and the speed at the moment.
Taking the difference between the present error and the error
of the previous sampling period, change of error is
calculated. According to the error and the change of error,
fuzzy logic controller calculates voltage change that should
be applied to the BLDC motor.
Fig.8: Matlab simulation model for BLDC with Fuzzy
Controller
 Simulation Results

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V. CONCLUSION
A fuzzy logic controller (FLC) has been employed for the
speed control of PMBLDC. The simulation model which is
implemented in MATLAB/Simulink environment allows
that many dynamic characteristics such as phase currents,
voltages, rotor speed, and mechanical torque can be
effectively considered. Furthermore, the control algorithms,
FLC and PI have been compared by using the developed
model. It is seen that the desired real speed and torque
values could be reached in a short time by FLC controller.
Fuzzy logic speed controller improved the performance of
PMBLDC Drive.
REFERENCES
[1] “Modeling and simulation of three level inverter FED
PMBLDC drive using AI technique”, Narmadha
T.V, vol.2, NO.1, 2010, PP.69-82.
[2] “Efficient Modeling for a Brushless DC Motor Drive’’,
P C K Luk' , C K Lee IEEE conference on industrial
electronics (IECON), 1994.
[3] “fuzzy logic in control systems: fuzzy logic control part
1 & part 2”, C.C.Lee,IEEE Trans. Syst.,
man,cybren,vol.20,no.2,pp.404-435, mar./apr.1990
[4] “Design of a Hybrid Fuzzy Logic Proportional Plus
Conventional Integral-Derivative Controller” Wei Li,
IEEE TRANSACTIONS ON FUZZY SYSTEMS,
VOL. 6, NO. 4, NOVEMBER 1998 449-463

395
[5] “Fuzzy Logic Based Position-Sensor less Speed Control
of Multi Level Inverter Fed PMBLDC Drive”,
Narmadha T.V, Thyagarajan T. JOURNAL OF
ADVANCES IN INFORMATION TECHNOLOGY,
VOL. 1, NO. 1, FEBRUARY 2010 52-58
[6] “Review of Multilevel Voltage Source Inverter
Topologies And Control Schemes”, Ilhami Colak ,
Ersan Kabalci , Ramazan Bayindir
[7] “Realization of Fuzzy Logic Controlled BLDC motor
drive using Matlab/Simulink” Mehmet Çunkaş and
Omer Aydoğdu, Mathematical and Computational
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[8] “Modeling and Simulation of Closed Loop Controlled
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[9] MATLAB/SIMULINK Documentations. (Help file)

Design of Fuzzy Logic Controller for Speed Regulation of BLDC motor using MATLAB

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Design of Fuzzy Logic Controller for Speed Regulation of BLDC motor using MATLAB