Design An Construction Of A Speed Control Of A DC Fan Using A Fuzzy Controller

ABSTRACT

Machines have served the humanity starting from a simple ceiling fan to higher industrial applications such as lathe drives and conveyor belts. This research work aims at providing an appropriate software based control system because it provides computer featured applications, prevents rapid signal loss, reduces noise while also significantly improves the steady state and dynamic response of the motor. In this research paper, we have worked on DC motors due to its significant advantages over other types of machine drives. We have first individually studied Fuzzy controller in controlling speed for a separately ex- cited DC motor. Afterwards, we have analyzed both results to conclude that which technique is better to be adopted for precisely controlling the speed of DC motor. Outcomes from MATLAB fuzzy logic toolbox for simulation of our schematic has been provided in this research work. Our study parameters include input voltage of DC motor, its speed, percentage overshoot and rising time of the output signal.

 TABLE OF CONTENTS

COVER PAGE

TITLE PAGE

APPROVAL PAGE

DEDICATION

ACKNOWLEDGEMENT

ABSTRACT

CHAPTER ONE

1.1   INTRODUCTION

1.2   BACKGROUND

1.3   BENEFITS OF USING FUZZY CONTROLLERS

1.4   OBJECTIVE OF THE PROJECT

1.5   PROBLEM STATEMENT

1.6   SCOPE OF THE PROJECT

CHAPTER TWO

LITERATURE REVIEW

2.1   OVERVIEW OF THE STUDY

2.2    REVIEW OF DIFFERENT TYPES DC MOTOR

2.3   REVIEW OF THE PREVIOUS STUDY

2.4  BRUSHLESS DIRECT CURRENT MOTOR

2.5   CONSTRUCTION AND OPERATING PRINCIPLE

2.6    THEORY OF OPERATION

2.7     TORQUE/SPEED CHARACTERISTICS

2.8    PRINCIPLE OF DC MOTOR

2.9     FUZZY LOGIC CONTROLLER SYSTEM

CHAPTER THREE

DESIGN METHODOLOGY

3.1      SYSTEM BLOCK DIAGRAM

3.2      STRUCTURE OF BLDC MOTOR

CHAPTER FOUR

4.0   TESTING ANALYSIS

CHAPTER FIVE

5.1     CONCLUSION

5.2     REFERENCES

CHAPTER ONE

1.0                                                        INTRODUCTION

Motor drives have been in use for long time and are an efficient way of transferring mechanical energy into de- sirable output in industries. Although there are two types of motor drives currently being used in every industry but DC motors can be considered much better than AC motors especially when considering transportation equipment because of their maximum torque producing quality at stalls which is very poor in AC motors. Also energy recovery mechanism observed in DC motors is much better than in AC motors [1]. Moreover dc motors provide a low horsepower rating at a much cheaper rate than AC drives [2]. To achieve maximum productivity, every single thing of a machine should be taken into account and analyzed accordingly. In motor control systems, hundreds of problems are faced such as change in load dynamics. The most important affecting factor will be noise parameter which is too much various and unpredictable affecting the functioning of the machine [3]. Similarly, another main factor is speed which should be monitored constantly according to the requirement for a desirable and reliable output.

A DC motor as the name indicates is a motor initiated usually by direct current and is converted into mechanical energy according to the requirement. DC motors are ruling the world due to their extensive use in modern technologies and in almost every industry such as to operate steel rolling mills, electric screw drivers, sewing machines, hard disk drives, air compressors, reciprocating machine etc. [4].

DC motors are generally classified into two types:

• Self-excited DC motor;
• Separately excited DC

The basic difference between the two types is that self-excited DC motor is initiated by its own field circuit while separately excited DC motor is initiated by an external input supply.

This research work aims at speed controlling of separately excited DC motor rather than self-excited DC mo- tor. We need variable speed drives in our everyday industries such as automotive, petrochemical, food and beverage etc. However, position control of machine drive is also important but once a position is adjusted by some mechanism then its need not to be changed accordingly again and again. However, speed of an object needs to be changed as required such as of motor used in blender. Sometimes it is required to blend the mixture at high speed and sometimes at medium or low speed. Therefore, a technique should be devised for variable speed con- trol rather than variable position control. The major reason of working on separately excited DC motor is that initiation of the motor is independent of internal circuitry of the machine. This gives us an advantage of gene- rating output as desired by varying input supplied voltage with accurate and better speed control as compared to self-excited DC motors. Separately excited DC motors are now extensively ruling the industries due to their marvelous inventions such as OEM battery-powered applications separately excited electric golf car dc motor etc. When considering hardware of a separately excited DC motor, speed can be controlled by following methods:

• By controlling Armature voltage of the machine [5];
• By adding variable resistance to armature circuit resistance [6].

Research studies have been done on using different controllers to control speed of separately excited DC mo- tor. Several mathematical models have been used to control speed of drive as discussed in [7] [8]. Different types of controllers used are Proportional Integral Controller (PI), Proportional Integral Derivative Controller (PID) etc.

The speed of motor is usually dependent on the type of motor used. Usually when a motor starts, it draws a higher current than an expected value due to a static friction associated with the motor. The higher current will always remain proportional to the input voltage. The input voltage verses speed of a specified machine drive has been analyzed carefully and corresponding outputs have been studied. Results are then analyzed to conclude that which controller is better. Fuzzy controller are monitored so as to give less  percentage overshoot and less rising time to make an efficient system and to minimize distortion.

Our research work has aimed on achieving precise and accurate speed control of separately excited DC motor by using Fuzzy Controller. The purpose is to provide a better speed control method by comparative study of two controllers.

1.1                                                       BACKGROUND

Machines have successfully replaced uncountable human efforts into efficient and reliable output. Both DC and AC machines are equally important suiting to the required application. Several researches have been done on improving reliability and efficiency in machines. They have not discussed that despite of so many advantages of AC machines for why only DC motors speed should be precisely and accurately controlled and how are they better than AC machines [9]-[11]. Similarly, no comparison of separately excited DC motor and self-excited DC motor is shown [12]-[15]. All parameters of DC motors are correlated such as load dynamics, angular machines, speed of drive etc. Angular position can be affected by changes in load and speed until and unless ideal case is assumed. Publication such as [16] has not focused on how angular position will be affected with variable speed of the drive. DC motors speed can be controlled by various methods of which most commonly used is fuzzy controller based on Mamdani and Sugeno systems. [17] [18] have not discussed the reason of using Mamdani system rather than preferring Sugeno system.

A feasible, proficient, workable and ultra-efficient system should always be designed for negligible percentage overshoot and minimum rising time. However, lowering of percentage overshoot and minimizing rise time often contradict and is not possible at one time. Publications like [19]-[21] have not shown any conclusion for controlling speed of DC drives by considering percentage overshoot and rising time.

To incorporate any method in a practical and systematic way for efficacious, operative and dynamic perfor- mance, results should be analyzed on the basis of comparison to conclude which method is better to be implemented. [22] does not contain any comparative technique.

1.2                              BENEFITS OF USING FUZZY CONTROLLERS

• Fuzzy controllers are more robust than PID controllers because they can cover a much wider range of operating conditions than PID can, and can operate with noise and disturbances of different
• Developing a fuzzy controller is cheaper than developing a model-based or other controller to do the same
• Fuzzy controllers are customisable, since it is easier to understand and modify their rules, which not only use a human operator’s strategy but also are expressed in natural linguistic
• It is easy to learn how fuzzy controllers operate and how to design and apply them to a concrete

1.3                            OBJECTIVE OF THE PROJECT

The objectives of this project are:

1. To derive simulation model of BLDC motor using Matlab
2. To improve speed performances of BLDC motor such as reduces overshoot; reduce rise time and steady state error by using Fuzzy Logic controller.

1.4                                                 PROBLEM STATEMENT

Direct Current (DC) motor was chosen for the speed control applications due to the control simplicity on the intrinsic decoupling between the flux and the torque. As the name implies, there are physical limitations to speed and life time because of brush wear. However, BLDC have been produced to overcome this problem. Since there are no carbon brushes to wear out, a BLDC motor can provide significantly greater life being now only limited by bearing wear. This advantage make BLDC motor becomes popular in the industry but this motor is a non-linear system hence, need more complex speed controller than the DC motor.

By this reason, the Gaussian Fuzzy Logic controller will be developed to improve the performance of variable speed for BLDC motor since the system of this motor is non-linear system.

1.5                                 SCOPE OF THE PROJECT

The scopes of this project are to simulate BLDC motor using Matlab Simulink software and develop the FLC that will be used to control the variable speed of the BLDC motor. The scopes of proposed FLC is limited to Gaussian membership function. The other membership function of FLC also will be develop to compare the effectiveness of the proposed controller.