1.1 instruments, machines tools etc. The main

1.1 BACKGROUND OF THE STUDY
The human problem our thesis work will solve is to reduce backlash in induction motor. Backlash been described as a mechanical form of dead band that can lead to error on hole location, if the motion required to machine the holes causes a reversal in axis direction it also causes loses of motion between reducer input and output shafts, making it difficult to achieve accurate positioning in equipment such as instruments, machines tools etc. The main problem electrically are vibrations from motor as a result of high ripple torque in the induction motor.
An induction motor is a kind of an AC machine in which alternating current is supplied to the stator directly and to the rotor by induction from the stator. Induction motor can appear in a single phase or a poly phase. (Toufouti, et al, 2013).
In construction, the induction motor has a stator which is the stationary portion consisting of a frame that houses the magnetically active angular cylindrical structure called the stator lamination. It stack punched from electrical steel sheet with a three phase winding sets embedded in evenly spaced internal slots.
The rotor which is the rotatory parts of an motor is made up of a shaft and cylindrical structure called the rotor lamination. It stack punched from electrical steel sheet with evenly spaced slots located around the periphery to accept the conductors of the rotor winding (Ndubisi, 2006).
The rotor can be a wound type or squirrel cage type.
in a poly phase motor, the three phase windings are displaced from each other by 120 electrical degrees in space around the air-gap circumference when excited from a balanced poly phase source, those windings (stator winding) will produce a magnetic field in the air-gap rotating at synchronous speed as determine by the number of stator poles and the applied stator frequency (Bimal, 2011).
In the controlling of electrical motor; the introduction of micro-controllers and high switching frequency semiconductor devices, variable speed actuators where dominated by DC motors.
Today, using modern high switching frequency power converters controlled by micro-controllers, the frequency phase and magnitude of the input to an AC motor can be changed and hence the motor’s speed and torque can be controlled. AC motors combined with their drives have replaced DC motors in industrial applications because they are cheaper, better reliability, less in weight, and lower maintenance requirement. Squirrel cage induction motors are most generally used than all the rest of the electric motors as they have all the advantages of AC motors and they are easy to build.
The main advantage is that induction motors do not require an electrical connection between stationary and rotating portion of the motor. Therefore, they do not need any mechanical commutators to the fact that they are maintenance free motors. Induction motors also have lesser weight and inertia, high efficiency and high over load capability. Therefore, they are cheaper and more robust, and less proves to any failure at high speeds.
Furthermore, the motor can be used to work in explosive environments because no sparks are produced.
Taking into account all the advantages outlined above, induction motors must be considered as the perfect electrical to mechanical energy converter. However, mechanical energy is more than often required at variable speeds, where the speed control system is not a trivial matter. The effective way of producing an infinitely variable induction motor speed drive is to supply the induction motor with three phase voltage of variable amplitude.
A variable frequency is required because the rotor speed depends on the speed of the rotating magnetic field provided by the stator. A variable voltage is required because the motor impedance reduces at low frequencies and the current has to be limited by means of reducing the supply voltage. (Schauder, 2013).
Before the days of power electronics, a limited speed control of induction motors was achieved by switching the three stator windings from delta connection to star connection, allowing the voltage at the motor windings to be reduced. Induction motors also available with more than three stator windings to allow a change of the number of pole pairs.
However, a motor with several windings is very costly because more than three connections to the motor are needed and only certain discrete speeds are available. Another method of speed control can be realized by means of a wound rotor induction motor, where the rotor winding ends are brought out to slip rings (Malik, 2013). However, this method obviously removes themain aim of induction motors and it also introduces additional losses by connecting resistor or reactance in series with the stator windings of the induction motors, poor performance is achieved.
With the enormous advances in converters technology and the development of complex and robust control algorithms, considerable research effort is devoted for developing optimal techniques of speed control for induction machines. Induction motor control has traditionally been achieved using field oriented control (FOC). This method involves the transformation of stator currents in a synchronous manner that is in line with one of the stator fluxes. The torque and flux producing components of the stator currents are decoupled, such that the component of the stator current controlling the rotor flux magnitude and the component controls the output torquewilldiffer (Kazmier and Giuseppe, 2013).
The implementation of this system however is complicated. The FOC is also well known to be highly sensitive to parameter variations. It also based on accurate parameter identification to obtain the needed performance.
Another induction motor control techniques is the sensor less vector control. This control method is only for both high and low speed range. Using the method, the stator terminal voltages and currents estimate the rotor angular speed, slip angular speed and the rotor flux. In this case, around zero speed, the slip angular velocity estimation becomes very difficult.
In the mid 1980’s, Takahashi and Noguchi introduced another induction motor control technique called direct torque control (DTC) for low and medium power application (Lamchichi, 2014). In this method, stator voltage vector is selected according to the differences between the reference and actual torque and stator flux linkage. DTC has a relatively simple control structure but gives maximum result as well as the field oriented control (FOC), technique. It is also known that DTC drives is low sensitive to parameters variations and gives a high dynamic performances like fastest response of torque and flux than classical vector control. This method allows a decoupledcontrol of flux and torque without using speed or position sensors, co-ordinate transformation, pulse width modulation (PWM) technique and current regulators. This type of command involves non-linear controller type of hysteresis, for both stator flux magnitude and electromagnetic torque.
But due to the principle of operation of these controllers which is based on the Boolean logic, none of the inverter switching vectors produced is able to generate the desired changes in torque and flux. However, torque and flux ripples composed a real problem in direct torque control induction motor drive (Faliha and Rachid, 2015).

Motivation for the work
When we were on training in machine in our office, we are told gave us a drawing to produce a machine shaft. During the process, when we feed in a cut of 10mm to the machine, it would cut 9.5mm and when we wanted to drill a hole at the center of the job, it would drilled it off centered, we called on our supervisor after we have wasted much time, power and materials. Surprisingly, after his supervision, he told us that backlash in the machine is responsible for that and he instructed us to use another machine which we did and got what we need immediately. Therefore, that ugly experience motivated us to research on how to reduce high ripple torque in induction motor which is the main causes of vibrations that lead to the backlash in the industrial machine.

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1.2 STATEMENT OF THE PROBLEM
• The statement of the human problem our research work will solve is to reduce backlash in industrial machine.
• Explanation of the problem

BACKLASH
Backlash can be defined as the maximum distance or angle through which any part of a mechanical system may be moved in one direction without applying appreciable force or motion to the next part in mechanical sequence and is a mechanical form of dead band. More so, it is any non-movement that occurs during axis reversals. For instance, when x – axis is commanded to move one inch in the positive direction, immediately, after this x – axis movement, these x-axis is also commanded to move one inch in the negative direction if any backlash exists in the x-axis, then it will not immediately start moving in the negative direction and the motion departure will not be precisely one inch.
So, it can cause positioning error on holes location, if the motion required to drill the holes causes a reversal in axis direction, it also causes loses ofmotion between reducer input and output shafts, making it difficult to achieve accurate positioning in equipment such as machines tools etc.
The main cause of this problem electrically is vibrations from electric motor as a result of high ripple torque in the induction motor.

• Benefits of solving the problem
1. High quality products will be produce.
2. Productivity will increase because adjustment and readjustment of machine feeding handle or feeding screw to eliminate backlash have been reduced.
3. Operational cost will reduced.
4. Greater efficiency will be guaranteed.
5. Greater accuracy and precision of product will be guaranteed.
6. Wasting of materials will be highly reduced.
1.3 RESEARCH OBJECTIVES
1. To develop a model that will control the error to achieve stability using DTC and fuzzy logic with duty ratio.
2. To determine the error in the torque of the machine that causes vibration which lead to backlash that result in production of less standard products.
3. To determine the position of the stator flux linkage space vector in the poles of the induction motor.
4. To determine the stator linkage flux error in the induction motor that also causes vibration.
5. To simulate the model above in the Simulink environment and validate the result.

1.4 SCOPE AND LIMITATION OF THE WORK
This project work is limited to the use of fuzzy logic controller with duty ratio to replace the torque and stator flux hysteresis controllers in the conventional DTC techniques. The controllers have three variable inputs, the stator flux error, electromagnetic torque error and position of stator flux linkage vector. The inference method used was the Mamdam fuzzy logic inference system. The deffuzzification method adopted in this work is the maximum criteria method.

1.5 SIGNIFICANCE OF THE WORK
The importance of this work in industry where induction motor drives are mainly in application cannot be over emphasis.
As earlier noted, induction motors because of their ruggedness simple mechanical structure and easy maintenance; electrical drives in industries are mostly based on them.
Also, a wide range of induction motor applications require variable speed, therefore induction motor speed, if not accurately estimated will affect the efficiency of the overall industrial processes. Equally, the harmonic losses if not put in check will shorten the life span and efficiency of the motor inverter.
Based on the above, it is aimed at reducing the principle causes of the inefficiency in the DTC induction motor and improves the performance of the system.
1.6 ORGANIZATION OF THE WORK
The work is organized into five chapters. Various control techniques were discussed in chapter two, in chapter three, we discusses the methodology, design and implementation of the direct torque control of induction motor using fuzzy logic with duty ratio controller.
Chapter four discusses data collection, analysis and the simulated results showing the system using conventional method of control and the proposed fuzzy logic with duty ratio method of control under applied load torque conditions.
Conclusion, recommendations and suggestion for further work are mentioned in chapter five.

1. would use to identify job opportunities

1. Describe at least three specific individual differences that may give you an advantage in the workplace. (1-3 sentences)
Answer:
Type your answer here. The three are being active and smiling and working hard.
(Score for Question 2: ___ of 1.0 points)
2. Choose an industry you might be interested in working in, and explain why this industry interests you. (2-4 sentences)
Answer:
Type your answer here. I want to work for Xbox company. The reason why is because I like to play games.
(Score for Question 3: ___ of 1.0 points)
3. Describe at least two methods you would use to identify job opportunities if you were looking for a job. Explain why you would use these methods. (2-4 sentences)
Answer:
Type your answer here. I will first see if they are hearing. Then I’ll get to know the hearing manger because if they like your personality they will hire you.
(Score for Question 4: ___ of 2.0 points)
4. Choose a career from the following list: financial planner, financial analyst, accountant, risk manager, cash manager, treasurer, CFO, and comptroller. Use the Internet to find information about this career, and answer the questions below. TIP: The U.S. Occupational Outlook Handbook (http://www.bls.gov/oco/) may be a good source for this information.
(a) What is the name of this career? (0.5 points)
(b) Describe at least two tasks a person with this career might perform. (1-2 sentences. 1.0 points)
(c) What level of education is this career likely to require? (0.5 points)
Answer:
Type your answer here. (A) Risk manager. (B) They help with the company to not lose money and with insurance rate. (C) You will need 4 years in collage.
(Score for Question 5: ___ of 2.0 points)
5. Choose another career from the following list: financial planner, financial analyst, accountant, risk manager, cash manager, treasurer, CFO, and comptroller. Use the Internet to find information about this career, and answer the questions below. TIP: The U.S. Occupational Outlook Handbook (http://www.bls.gov/oco/) may be a good source for this information
(a) What is the name of the career you chose? (0.5 points)
(b) Describe at least two tasks a person with this career might perform. (1-2 sentences. 1.0 points)
(c) What level of education is this career likely to require? (0.5 points)
Answer:
Type your answer here. (A) CFO. (B) They do budget managing and benefit analysis. (C) You will need a bachelor’s degree.
(Score for Question 6: ___ of 4.0 points)
6. Choose another career that you are interested in. This does not need to be a career in the finance industry. Use the Internet to find information about this career, and answer the questions below.
(a) What is the name of the career you chose? (0.5 points)
(b) Describe at least two tasks a person with this career might perform. (1-2 sentences. 1.0 points)
(c) What level of education is this career likely to require? (0.5 points)
(d) Why does this career interest you? (1-3 sentences. 1.0 points)
Answer:
Type your answer here. (A) comptroller. (B) They see daily accounting operations of a business and they do accounting task. (C) Bachelor’s degree in financial or business-related field. (D) This job year salary is $117,990.
(Score for Question 7: ___ of 4.0 points)
7. Choose another career that you are interested in. This does not need to be a career in the finance industry. Use the Internet to find information about this career, and answer the questions below.
(a) What is the name of the career you chose? (0.5 points)
(b) Describe at least two tasks a person with this career might perform. (1-2 sentences. 1.0 points)
(c) What level of education is this career likely to require? (0.5 points)
(d) Why does this career interest you? (1-3 sentences. 2.0 points)
Answer:
Type your answer here. (A) cash manager. (B) cash administration, management of current accounts and bank relations. (C) You will need a bachelor’s degree. (D) I’m really good with money.
(Score for Question 8: ___ of 2.0 points)
8. If you were in charge of managing a group of employees, how would you assess their job performance? Describe at least two methods you would use. (2-4 sentences)
Answer:
Type your answer here. I will see if they are smiling. Also ill see if they have good manners to the costumer.
(Score for Question 9: ___ of 1.0 points)
9. Describe a time when you or someone you know conformed to the behavior of others. Why do you think this person chose to conform? (2-4 sentences)
Answer:
Type your answer here. Billy wanted a job and at his interview they said he has to have good manners. He wanted the job.
(Score for Question 10: ___ of 1.0 points)
10. Describe a time when you or someone you know chose not to conform to the behavior of others. Why do you think this person chose not to conform? (2-4 sentences)
Answer:
Type your answer here. John went to an interview and he didn’t like what the other is saying. He didn’t like the rules.
(Score for Question 11: ___ of 3.0 points)
11. Describe a time when you have worked with a group of people, such as with students for a school project, with coworkers at a job, or with family members to complete a chore. Describe the dynamics of the group, and then describe at least one way the group dynamics could have been improved. (3-6 sentences)
Answer:
Type your answer here. So me and my brothers were cleaning house. So one person had to clean the bathroom and one mops and the other vacuum. This was the best way to get thing done fast.
(Score for Question 12: ___ of 2.5 points)
12. Describe a real or made up but realistic example of a misunderstanding that occurred because of unclear written or verbal communication. How could this misunderstanding have been avoided? (3-6 sentences)
Answer:
Type your answer here. John didn’t read his email fully and thought his interview was at 9 pm but it was at 9 am. So he missed it and didn’t get a job. If john would have read his email fully he wouldn’t miss his interview.

1. Bible are sold. 12. Oldest man in

1. The word ‘bible’ is a Greek word which means ‘the books’.
2. The Bible was written roughly between 1200 and 100 AD.
3. There are 66 books in Protestants Christians Bible.
4. Ethiopian Orthodox Christians recognize 81 books in the Bible.
5. Greek Orthodox Bible has 75 books in the bible.
6. Most parts of Old Testament was written in Hebrew.
7. The New Testament is written in Greek.
8. The complete Bible is translated in around 670 different languages.
9. Bible is most famous and most published book in the world.
10. The New Testament is translated into 1521 languages.
11. Every year approximately 100 million copies of the Bible are sold.
12. Oldest man in the bible is Methuselah, he lived for 969 years.
13. The Bible has more than a single author, it was written by kings, fisherman, prophets, shepherds, poets, farmers, musicians, doctors and many others.
14. There are poetry, legal documents, songs, letters, eyewitness accounts, people stories, historical documents and advice material in Bible.
15. Most Catholics recognize 73 books in the Bible.
16. According to the stories in the bible, Satan killed only 10 people but God killed more than 2,400,000 people.
17. To read the entire Bible, it takes 49 hours, i.e. slightly more than 2 days.
18. Goliath was the tallest man in the Bible; he was 9 and half feet tall.
19. The first English translation of Bible was made in 1382 A.D., by John Wycliffe.
20. The shortest book in the New Testament is 2 John with 13 verses.
21. Acts is the longest book in the New Testament is. It has 28 chapters.
22. Women, old people are the most maximum readers of the Bible.
23. Noah built the ark to protect family and animals to survive the flood, and he was 600 years old when he made an ark.
24. According to Bible Jesus lived on the earth for forty days after his supernatural resurrection.
25. The longest Chapter in the Bible is Psalm 119.
26. The shortest Chapter in the Bible is Psalm 117.
27. The bible is the most shoplifted book.
28. The longest verse in the Bible is Esther 8:9.
29. There are total 1189 numbers of Chapters in the Bible.
30. There are two men in the Bible who were taken up to heaven by God, without dying. They are Elijah and Enoch,
31. There is a description in Bible that after Crucifixion of Jesus, many saints rose from dead and were seen by people.
32. China is world’s largest producer of Bibles.
33. The words: “Do not be afraid” appear 365 times in the Bible.
34. Total number of Chapters in the Old Testament is929.
35. There are 260 Chapters in the New Testament.
36. The word “Christian” appears only 3 times in the Bible.
37. “Mahershalalhashbaz” is the longest word in the Bible.
38. “Amen” is the last word in the Bible.
39. Bible has 100 positive statements about the right hand.
40. There are no original texts of the bible.
41. The Old Testament was written in 1000 of years but New Testament was written in a period of 50-75 years.
42. There are many songs lyrics that are inspired by Bible.
43. As bible is offered for free in hotels and worship places it is the most commonly stolen book in the world.
44. After the death of Bob Marley, he was buried with his guitar, a Bible and stalk of marijuana.
45. There is no phrase in Bible like ‘God never gives you more than you can handle’ but the opposite is said in the bible.
46. Solomon was the wisest man in the Bible.
47. Jehovah’s Witnesses don’t celebrate holidays and birthdays.
48. Swearing on the Bible is forbidden by the Bible.
49. 7, 12 and 40 are the numbers the bible repeatedly repeats.
50. The most highlighted or read Kindle books are The Bible, Steve Jobs’ bio, and the Hunger Games.
51. Having Bibles, watching South Korean movies and distributing pornography in North Korea may be punished with death.
52. Dominican Republic flag has the bible on it.
53. In Bible, there is no physical description of Jesus.
54. Two London Bible printers in 1631accidentally left the word “not” out of the seventh commandment, which then read, “Thou shalt commit adultery.”
55. In the Bible, ‘666’ number is a sign of the beast.
56. There are plenty of puns, funny names, humorous imagery, sarcasm and irony in Bible.
57. In the bible, there is no mention of three wise men, just three gifts.
58. Bible states that the Earth is free floating in the space.
59. In the Bible, God sends 2 bears to murder 42 children because they had mocked the bald man.
60. The Old Testament has more than 60 passages; Christians believe its prophecies of Jesus.
61. There is mention of unicorns in Bible.
62. In Bible the greatest warrior was Gideon, he defeated 135,000 Midianites with the help of God.
63. According to Bible, Solomon had 700 wives and 300 concubines.
64. There is a description in Bible that earth is round.
65. There are around 2,500 prophecies in Bible.
66. “Jesus wept” is the shortest verse in the bible.
67. There are total 31,173 Verses in the Bible.
68. Most scholars believe that Jesus never viewed himself as creating a new religion per se, just reforming Judaism.
69. Jesus had several sisters and brothers, names of sisters are not named in the Bible.
70. The Bible contains around 774,000 words.

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