universiti teknologi malaysia
PSZ 19:16 (Pind. 1/07)
UNIVERSITI TEKNOLOGI MALAYSIA DECLARATION OF THESIS / UNDERGRADUATE PROJECT PAPER AND COPYRIGHT
Author’s full name :
MOHAMMAD SYAHIM BIN KHAIRUDIN
Date of birth
:
20TH APRIL 1987
Title
:
AN ELECTRIC G0-KART USING BLDC MOTOR AS PROPULSION SYSTEM
Academic Session :
20102011/2
I declare that this thesis is classified as :
√
CONFIDENTIAL
(Contains confidential information under the Official Secret Act 1972)*
RESTRICTED
(Contains restricted information as specified by the organization where research was done)*
OPEN ACCESS
I agree that my thesis to be published as online open access (full text)
I acknowledged that Universiti Teknologi Malaysia reserves the right as follows: 1. The thesis is the property of Universiti Teknologi Malaysia. 2. The Library of Universiti Teknologi Malaysia has the right to make copies for the purpose of research only. 3. The Library has the right to make copies of the thesis for academic exchange.
Certified by :
NOTES :
SIGNATURE
SIGNATURE OF SUPERVISOR
870420-14-5257
PROF. DR. NIK RUMZI NIK IDRIS
(NEW IC NO. /PASSPORT NO.)
NAME OF SUPERVISOR
Date : 18TH MAY 2011
Date : 18TH MAY 2011
*
If the thesis is CONFIDENTAL or RESTRICTED, please attach with the letter from the organization with period and reasons for confidentiality or restriction.
“I hereby declare that I have read this project report and in my opinion this project report is sufficient in terms of scope and quality as dissertation for the Bachelor of Engineering (Electrical).”
Signature
:
_______________________________
Name of Supervisor
:
PROF. DR. NIK RUMZI NIK IDRIS
Date
:
18th MAY 2011.
PSZ 19:16 (Pind. 1/07)
AN ELECTRIC GO-KART USING BLDC MOTOR AS PROPULSION SYSTEM
MOHAMMAD SYAHIM BIN KHAIRUDDIN
Submitted to the Faculty of Electrical Engineering in partial fulfillment of the requirements for the degree of Bachelor of Engineering (Electrical)
Faculty of Electrical Engineering Universiti Teknologi Malaysia
MAY 2011
ii
I declare that this project report entitled “An Electric Go-Kart Using BLDC Motor as Propulsion System” is the result of my own research except as cited in the references. The report has not been accepted for any degree and is not concurrently submitted in candidature of any degree.
Signature
:
_________________________________________
Name
: MOHAMMAD SYAHIM BIN KHAIRUDDIN
Date
: 18th MAY 2011
iii
Dedicated to my beloved parent Khairuddin Shaari and Zainab Idris That raised and taught me to be the person I am today. Also to Prof. Dr. Nik Rumzi Nik Idris who never stop guide me and taught me everything that relate to this project. Not to forget to my family members and friends… Thank you for all your supports…….
iv
ACKNOWLEDGEMENT
Praises and thanks to Allah for giving me the opportunity to complete this project.
I would like to express my highest gratitude to my supervisor, Prof. Dr. Nik Rumzi Nik Idris for his valuable guidance and advices to complete this project. Even there are so many challenge of doing this project; he never gives up guiding me. Thank u very much sir.
Besides, I want to express my deepest thanks to Hadi Harmaini and Aswad, who always stay besides me during completing this project. They are not just a good friend, but a partner thru this project. I am also indebted to Mr. Subkhi, and Mr. Khalid who always taught us to understand more about the project. Without them, me and my partners would be lost on understanding the project.
I am also indebted to Universiti Teknologi Malaysia (UTM) particularly Faculty of Electrical Engineering (FKE) for their assistance in carrying out my project and provided accommodations to fulfill the objectives of this project.
Last but not least, a deeply appreciation are given to my family and friends for their loves, encouragement and moral support.
v
ABSTRACT
This report presents an electric go-kart are the only viable solution to replace the conventional go-kart in order to reduced air pollution, in particular, in large urban areas. A brushless direct current motor is used as propulsion system. An overview of propulsion system design and the operational of BLDC motor are presented. BLDC motors have advantages over brushed DC motors and induction motors. They have better speed versus torque characteristics, high dynamic response, high efficiency, long operating life, noiseless operation, higher speed ranges, rugged construction and so on. In addition, the voltage regulator circuit IC 7805 is use to convert from 12V from lead acid battery to constant 5V DC and supply to the regulator output from motor controller. The new designed of accelerator pedal potentiometer also has been introduced in this project. The accelerator pedal will control a potentiometer which is wired into the drive control unit to control the amount of energy flowing into the drive. The prototype has been designed specifically to meet the requirement of low cost and it contains all of the active functions required to implement the control of the go-kart.
vi
ABSTRAK
Repot ini menyampaikan go-kart elektrik adalah satu-satunya penyelesaian yang layak untuk menggantikan go-kart konvensional untuk mengurangkan pencemaran udara, khususnya, di kawasan bandar besar. Sebuah motor BLDC digunakan sebagai sistem propulsi. Ulasan tentang propulsi sistem dan operasi motor BLDC dikemukakan. Motor BLDC mempunyai kelebihan lebih dari motor DC dan motor induksi. Ianya mempunyai ciri-ciri kelajuan yang lebih baik terhadap daya kilas, respon dinamik tinggi, kecekapan tinggi, jangka hayat operasi yang panjang, pengurangan bunyi motor, rentang kelajuan yang lebih tinggi, binaan yang kukuh dan sebagainya. Selain itu, pelaras voltan IC 7805 yang digunakan untuk menukarkan dari 12V dari asid bateri ke 5V arus terus konstan dan membekalkan ke penyelarasan keluaran dari pengawal motor. Reka bentuk pedal gas perintang laras yang baru telah dikenalkan dalam projek ini. Pedal gas akan mengendalikan peringtang laras dimanna disambung kabel ke unit pemacu kawalan untuk mengawal jumlah tenaga mengalir ke dalam pemacu. Prototaip ini telah direka khusus untuk memenuhi keperluan kos rendah dan mengandungi semua fungsi aktif yang diperlukan untuk melaksanakan kawalan go-kart.
vii
TABLE OF CONTENTS
CHAPTER
1
CONTENT
PAGE
DECLARATION
ii
DEDICATION
iii
ACKNOWLEDGMENT
iv
ABSTRACT
v
ABSTRAK
vi
TABLE OF CONTENTS
vii
LIST OF FIGURES
x
LIST OF TABLES
xi
LIST OF SYMBOLS AND ABBREVIATIONS
xii
INTRODUCTION
1
1.1
Background of Project
1
1.2
Problem Statement
2
1.3
Objective of the Project
2
1.4
Scope of the Project Report
2
1.5
Project Organization
3
viii 2
3
4
LITERATURE REVIEW
4
2.1
Project Review
4
2.2
BLDC Motor
5
2.2.1
Stator and Rotor
6
2.2.2
Theory of Operation
7
2.2.3
Torque/Speed Characteristics
8
2.2.4
Commutation Sequences
9
2.3
Voltage Regulator “7805”
11
2.4
Mechanical Parts Design
12
2.4.1
Go-Kart Frame
12
2.4.2
Designed Go-Kart Parts
12
METHODOLOGY
13
3.1
BLDC Motor
13
3.2
Designed Voltage Regulator 5V
14
3.3
Designed Go-Kart Frame
15
3.4
Mounted the Motor
15
3.5
Steering System Assembly
16
3.6
Pedal Potentiometer
17
3.7
Mechanical Job Related
18
RESULTS AND DISCUSSION
19
4.1
Introduction
19
4.2
Hall Effect Sensor Phase Shift
19
4.3
Frequency Motor
20
4.4
Motor Speed
22
ix
5
4.5
Phase Currents
23
4.6
Pedal Potentiometer
25
4.7
Integrate Complete Circuit of Go-Kart
26
4.8
Working Progress
28
CONCLUSION AND RECOMENDATION
29
5.1
Conclusion
29
5.2
Recommendation
30
REFERENCES
31
Appendices A-B
32-36
x
LIST OF FIGURES
FIGURE NO.
TITLE
PAGE
2.1
Block diagram of system electric go-kart
4
2.2
BLDC motor
5
2.3
Trapezoidal motor
6
2.4
Sinusoidal motor
6
2.5
Torque/Speed characteristics
8
2.6
Winding energizing sequence with respect
9
to the hall sensor 2.7
Hall sensor signal, back EMF, output torque
10
and phase current 2.8
7805 IC voltage regulators
11
3.1
Characteristic of BLDC motor “BM142HQ1000W48V”
13
3.2
Controller wiring diagram
14
3.3
Regulate speed block diagram
14
3.4
Go-kart frame
15
3.5
Materials selection
15
3.6
Welded shaft
16
3.7
Mounted motor
16
3.8
Steering system
17
3.9
Pedal potentiometer systems
17
3.10
Mechanical job related
18
4.1
Hall Effect sensor output waveform
20
4.2
Frequency output
20
4.3
Frequency motor vs voltage applied
21
4.4
Motor speed vs voltage applied
23
xi 4.5
Phase current
24
4.6
Phase current vs voltage applied
25
4.7
Pedal potentiometer
26
4.8
Integrated circuit
26
4.9
Black box
27
4.10
(a) Chassis (b) Chassis after grinded (c) Mounted motor
28
(d) Mounted seat and steering (e) Integrated all circuit (f) Complete designed with pedal (g) Complete go-kart assemble 1A
Digital intelligent brushless DC motor controller
32
wiring diagram 1B
Manual for BLDC motor model „BM 1424HQ‟
33
LIST OF TABLES
TABLE NO.
TITLE
PAGE
4.1
Result for frequency motor for forward motoring
21
4.2
Result for frequency motor for reverse motoring
21
4.3
Result for motor speed for forward motoring
22
4.4
Result for motor speed for reverse motoring
22
4.5
Result for phase current for forward motoring
24
4.6
Result for phase current for reverse motoring
24
xii
LIST OF SYMBOLS AND ABBREVIATIONS
BLDC
-
Brushless Direct Current
DC
-
Direct Current
ECF
-
Electronically Commutated Motors
EMF
-
Electromagnetic Force
PWM
-
Pulse Width Modulation
RPM
-
Rotational Per Minute
RPS
-
Rotational Per Second
xiii
LIST OF APPENDICES
APPENDIX
A
TITLE
PAGE
Digital intelligent brushless DC motor controller wiring
32
diagram
B
Manual for BLDC motor model „BM 1424HQ‟
33
C
Voltage regulator 7805 datasheet
34
D
Experimental setup
36
CHAPTER 1
INTRODUCTION
1.1
Background of Project
Nowadays, electric Go-Kart is gaining popularity in urban community. It is one of the new hobbies for the new generations. There are many methods in building the electric go kart. One of the methods is by using the Brushless DC (BLDC) motor as the propulsion system. The prototype has been designed specifically to meet the requirement of low maintenance and low noise generation.
The basic principle of Go-Kart using fuel is much the same as with the battery electric Go-Kart, but with a fuel cell or metal air battery replacing the rechargeable electric battery. The concept of the battery electric Go-Kart is essentially simple. The Go-Kart consists of an electric battery for energy storage, an electric motor, and a BLDC controller. The battery is normally recharged from mains electricity via a plug and a battery charging unit that can either be carried onboard or fitted at the charging point. The controller will normally control the power supplied to the motor, and hence the Go-Kart speed, in forward and reverse. This is normally known as a 2 quadrant controller, forwards and backwards. It is usually desirable to use regenerative braking both to recoup energy and as a convenient form of frictionless braking. When in addition the controller allows regenerative braking in forward and reverse directions it is known as a 4 quadrant controller. There is a range of
electric
vehicles
of
this
type
currently
available
on
the
market.
2
Four-quadrant converter is used to control the DC motor drives that require forward and reverse motoring as well as forward and reverse breaking.
1.2
Problem Statement
Although riding the Go-Kart seems to be the „in‟ thing for now, but most people are unaware of the consequences riding the conventional ones. There are several disadvantages of using Conventional Go-Kart. It needs regular maintenance by spending money on fuel gas and engine oil. Although during repairing Conventional Go-Kart it is too oily and the engine too noisy during generation. It is not suitable too repair it at the house cause of neighborhoods living surround. During playing the Conventional Go-Kart, the smoke that come from the exhaust will make air pollution. This project „Electric Go-Kart‟ by using BLDC motor is the recommended system to help prevent the disadvantages of using conventional ones.
1.3
Objectives of the Project
The objectives of this project are as listed below: 1. To learn and identify operation of BLDC Motor and Controller. 2. To design the complete circuit of Go-Kart including, accelerator paddle, steering, brake, and Go-Kart frame.
1.4
Scopes of the Project
1. Study, investigate and understand the BLDC motor. 2. Design a accelerate paddle in order to measure the speed. 3. Integrate complete circuit of Electric Go-Kart 4. Conduct experiment in Energy Conversion Lab.
3
1.5
Project Organization
This thesis consists of five chapters. In the first chapter, it discuss about the objective and scope of this project as long as summary of works. While Chapter 2 will discuss more on theory and literature reviews that have been done. It well discusses about the operation and construction principle, torque/speed characteristic and commutation sequence. In Chapter 3, the discussion will be on the research methodology implementation of this project. It is consisting in two parts, electronic designed and mechanical designed. The result and discussion will be presented in Chapter 4. The results discussed in this chapter were obtained by conducted experiment to analyze and identified the output of motor such as Hall Effect sensor phase shift, frequency motor, speed of motor and phase current. Last but not least, Chapter 5 discusses the conclusion and recommendation of this project.
CHAPTER 2
LITERATURE REVIEW
2.1
Project Review
The project is divided into three sections, which are BLDC Motor and Controller, Rechargeable Batteries, and speed measurement. This project is responsible for the first section. BLDC Motor is one of the motor types rapidly gaining popularity because of its have many advantages. This section will identify and learn the operation of BLDC Motor and the connections of the controller to create accelerate paddle in order to measure the speed. Another responsibility is to create a circuit that can supply 5V constantly to the controller and design complete circuit of go-kart.
Figure 2.1: Block diagram of system electric go-kart
5
2.2
BLDC Motor
Brushless direct current motors (BLDC motors) also known as ECM (electronically commutated motors) are synchronous electric motors generated by Direct Current electricity and having electronic commutation systems, rather than mechanical commutators and brushes.[2] It is uses a permanent magnet external rotor, three phases of driving coils, one or more Hall Effect devices to sense the position of the rotor, and the associated drive electronics. They act as three-phase synchronous motors containing their own variable frequency drive electronics where the coils are activated, one phase after the other, by the drive electronics as cued by the signals from the Hall Effect sensors. BLDC motors have many advantages over brushed DC motors and induction motors. There are, low cost of maintenance due to absence of brushes, simple and inexpensive control, and noiseless operation.
BLDC motors are synchronous motor because of magnetic field generated by the stator and the magnetic field generated by the rotor rotates at the same frequency. BLDC motors do not have the “slip” that is normally seen in induction motors.
Figure 2.2: BLDC motor
6
2.2.1
Stator and Rotor
The stator of a BLDC motor consists of stacked steel laminations with windings placed in the slots that are axially cut along the inner side-line. They have three stator windings with star connection in most of BLDC motor. Each of these winding are build with plentiful of coils interconnected to form a winding and many coils are placed in the slots and they are interconnected to make a winding where will distributed even numbers of poles. There are two types of stator windings alternatives, trapezoidal and sinusoidal motors. Advantages of using sinusoidal motors, the torque output smoother than that of a trapezoidal motor. However, this comes with an extra cost, as the sinusoidal motors take extra winding interconnections because of the coils distribution on the stator periphery, thereby increasing the copper intake by the stator windings. That will make trapezoidal more cheaply than sinusoidal motors. [1]
Since the rotor is made of permanent magnet, it can vary from two to eight pole pairs with alternate North (N) and South (S) poles. There are two types of magnetic material use in BLDC motor, there are Ferrite Magnets and Alloy Magnets. The ferrite magnets are inexpensive but they have the disadvantage of low flux density for a given volume. Compare to the alloy material has high magnetic density per volume and enables the rotor to compress further for the same torque. In addition, these alloy magnets improve the size-to-weight ratio and give higher torque for the same size motor using ferrite magnets.
Figure 2.3: Trapezoidal motor
Figure 2.4: Sinusoidal motor
7
2.2.2
Theory of Operation
Stator windings should be energized in a sequence in order to rotate the BLDC motor. Identify the rotor position in order to understand which winding will be energized following the energizing sequence is very importance. Rotor position is sensed using Hall Effect sensors. Whenever the rotor magnetic poles pass near the Hall sensors, they give a high or low signal (1 or 0), indicating the N or S pole is passing near the sensors. The sequence of commutation can be determined based on the combination of three Hall sensor signals. There have two type of phase shift of The Hall Sensors, 60° or 120° phase shift to each other. Each commutation sequence has one of the windings energized to positive power where current enters into the winding and exits as negative on the second winding while the third is in a nonenergized condition. The interaction between the magnetic field generated by the stator coils and the permanent magnets (rotor) will produce torque.[1]
8
2.2.3
Torque/Speed Characteristics
The motor can be loaded up to the rated torque during continuous operation. The torque will remain constant for a speed range until the rated speed. After that the torque will start dropping in order to run up the motor to 150% of the rated speed (maximum speed).The motor need more torque than the rated for application acceleration and deceleration. During acceleration and motor starts from standstill, extra torque is required to overcome the inertia of the load and the rotor itself. As long as it follows the speed torque curve, the motor can deliver a higher torque, maximum up to peak torque.
Figure 2.5: Torque/Speed characteristics
9
2.2.4
Commutation Sequences
One of the Hall sensors changes the state and it takes six steps to complete an electrical cycle in every 60 electrical degrees of rotation and also the phase current switching will be updated. Rotor pole pairs will determine the number of electrical cycles to be repeated to complete a mechanical rotation. It means for each rotor pole pairs is equal to one electrical cycle is completed. So, the number of electrical cycles/rotations equals the rotor pole pairs. To vary the speed, these signals of PWM should at a much higher frequency than the motor frequency, at least 10 times that of the maximum frequency of the motor. [3] When the average of voltage supplied to the stator reduces, the speeds will reduce if only the duty cycle of PWM is varied within the sequences,
Figure 2.6: Winding energizing sequence with respect to the hall sensor
10
Figure 2.7: Hall sensor signal, back EMF, output torque and phase current
11
2.3
Voltage Regulator “7805”
IC Regulator 7805 is a positive voltage regulator, used to produce fixed voltage regulation. It can supply output currents until 1A when used with suitable heat sink. The last two number (78“05”) shows the value of output voltage regulation. So that it will produce fixed 5V output voltage. It can take a higher DC voltage and turn it into constant 5V DC. It needs input voltage at least 2V higher than 5V output voltage and not more than 30V input voltage. The capacitors connected to voltage regulator are optional, but it will make output voltage smoother.
Figure 2.8: 7805 IC voltage regulators
12
2.4
Mechanical Parts Design
An Electric Go-Kart is a small vehicle with simple design. It consists of small body build, four wheels, paddle potentiometer, brake and an electric motor. A lot of time is spent to build it has to be performed seriously. The important things is to take seriously in building an electric go-kart which requires time, special tools, dedication, and money.
2.4.1
Go-Kart Frame
There are two type of steel for the go-kart frame: 1. Round Pipe - Pipe steel on a go-kart looks organized but it is harder to maneuver and weld together. 2. Angular Square - Square steel is easier to bend or join and it‟s cheaper, but not so good to look at.
2.4.2
Designed Go-Kart Parts
The first step to be considered in assembling go-kart frame is to design first and always measure the steel materials twice and noted it to make sure that the particular length is right. Never use welded pieces for the main supporting parts. Be sure to measure the length and width before welding each piece.
CHAPTER 3
METHODOLOGY
3.1
BLDC Motor
In this project, BLDC Motor model “BM142HQ1000W48V” was used. The specifications were given from manufactured. It also comes with the controller.
Figure 3.1: Characteristic of BLDC motor “BM142HQ1000W48V”
14
Voltage 48V DC Power Rate 1KW Regulator 1.2-5V Phase Degree 120° Max Current 60A Figure 3.2: Controller wiring diagram
3.2
Designed Voltage Regulator 5V
The purpose of creating the voltage regulator circuit is to maintain a constant 5V level and supply it to regulator speed output from BLDC Motor Controller. Input voltage for voltage regulator is 12V from Lead Acid Battery. The range of speed to be regulated is starts from 1.2V to 5V. Actually the voltage is to control the current field flow inside the motor. Then torque has been developed from current field. This is on how the speed of the motor can be regulated. The capacitor is connected to the voltage regulator to in order to obtain a smoother output. The potentiometer 50kΩ is connected to the output voltage regulator to regulate the speed.
Figure 3.3: Regulate speed block diagram
15
3.3
Designed Go-Kart Frame
The go-kart frame had been grinded and altered to make it more presentable. All size and type of steel needed to build the parts of go-kart has been listed down before welding each piece of it. Use support to get proper height and ground clearance of parts to be welded. Set up the seats on the go-kart frame to get the size of frame and slots to mount the motor.
Figure 3.4: Go Kart frame
3.4
Figure 3.5: Materials selection
Mounted the Motor
To fit the engine parts into the go-kart frame, the shafts were cut in proper length and welding it back by male and female technique. The steel frames also being cut, drilled into, and welded together. This to ensure that the go kart can be performed carefully. Three solid metal plates have been designed for holding and mounted motor on go-kart frame. This will give firm results.
16
Figure 3.6: Welded shaft
3.5
Figure 3.7: Mounted motor
Steering System Assembly
Steering part on the frame has been clips with steel plate and a hole is made on steel plate to clip with bolts and nuts. The right size of nuts is being used to lock the bolts. The washer is located in between of each nut and bolt. This method is to avoid warp and wear. Steering system assembly function is to keep rear and front, wheels aligned and not hard-pressed away to each other. It will give smooth direction of go-kart with durable construction. There are other essential parts that make go-kart easy to maneuver. They are: 1. Spindles: Spindles act like axles when in the front of go-kart. Spindle is the most essential parts in steering system assembly. 2. Steering shaft: It is located between steering wheel and ends at the bottom go kart frame with pitman arm. 3. Pitman arms: It is located at the bottom of the steering shaft. Pitman arm connected to the tie rods and it will push it towards the desired direction whenever steering wheel has been turn together with steering shaft. 4. Tie rod: This part connected with the pitman arm and the spindles.
17
Tie rod
Steering wheel
Steering shaft
Spindle Pitman arm
Figure 3.8: Steering system
3.6
Pedal Potentiometer
The speed of motor is controlled by the potentiometer. Therefore the gas pedal was altered to control the potentiometer which is wired into the BLDC controller to control the amount of power flowing into the motor. The tapper is used to make a trip on the knob of potentiometer so that the nut will be tied up the knob and throttle plate on the chassis. Two holes were drilled at the front and back. The first hole is to fit the potentiometer and the second hole is to tie up with the spring in order to keep the potentiometer travel back at first position whenever the paddle has been pressed. The cable stopper is designed to ensure cable can travel in a straight line as possible.
Figure 3.9: Pedal potentiometer systems
18
3.7
Mechanical Job Related
There are several mechanical jobs related during the building of an electric go-kart process. There are: 1. Grinding - Process to get a smooth surface of the go-kart frame. 2. Tapping - Process to grind with a suitable angle on the metal before welding. 3. Material Selection - Process to select suitable steel needed. 4. Cutting - Process to cut a steel to get length and width needed. 5. Drilling - Process to make a hole on the plate and steel. 6. Welding - Process to join a material in order to get a strong joint.
Grinding
Tapping
Material Selection
Drilling
Welding
Cutting
Figure 3.10: Mechanical job related
CHAPTER 4
RESULTS AND DISCUSSIONS
4.1
Introduction
The results discussed in this chapter are obtained by conducting experiments by analyzing and identifying the output of motor such as Hall Effect sensor phase shift, frequency motor, speed of motor and phase current. The objective is to test the output result whether it is the same with the specifications given by the manufacturer. The speed of the motor can be achieved from zero to maximum speed is being discovered by testing on the design of the pedal potentiometer. With these processes, it can determine and distinguish on the successfulness of the project‟ objectives.
4.2
Hall Effect Sensor Phase Shift
In this part, experiment is conducted to determine the phase shift motor. The phase difference between of two hall sensor output had been tested. Below are the results captured by using two different hall sensor output.
1 cycle = 12ms 1 cycle = 360° Different shift between green and blue output = 4ms (4ms/12ms*360°) = 120° phase degree different
20
Figure 4.1: Hall Effect sensor output waveform
4.3
Frequency Motor
The experiment in determining the frequency of the motor had also been conducted. The data of motor frequency from Hall Effect sensor output waveform for forward and reverse motoring was collected. Voltmeter is used to check on the output voltage regulator from BLDC controller. The output of Hall Effect sensor started to run at 1.2V; in which the result is the same with data sheet given by the manufacturer.
Figure 4.2: Frequency output
21
Table 4.1: Result for frequency motor for forward motoring Voltage(V) Time(ms) Frequency(Hz)=1/T 1.2 170 5.88 1.5 20 50 2 11 91 2.5 7 142.85 3 5.5 181.81 3.5 4.5 222.22 4 4.5 222.22 4.58 4.5 222.22
Table 4.2: Result for frequency motor for reverse motoring Voltage(V) Time(ms) Frequency(Hz)=1/T 1.2 170 5.88 1.5 20 50 2 11 100 2.5 7 111.11 3 5.5 111.11 3.5 4.5 111.11 4 4.5 111.11 4.58 4.5 111.11
Frequency Motor(Hz)
Frequency Motor vs Voltage Applied
250 200 150 100 Reverse Motoring
50 0 1.2
1.5
2
2.5
3
3.5
4
4.58Voltage Applied (v)
Figure 4.3: Frequency motor vs voltage applied
22
From the results obtained, it can be conclude that the BLDC motor starts to turn when the voltage regulator is adjusted to 1.2V. The frequency of output Hall Effect sensor for forward motoring is higher than reverse motoring. The relationship between frequency motor and regulated voltage is linear until it reaches the maximum frequency. For forward motoring, the maximum frequency (222.22Hz) is reached at 3.5V. Meanwhile for reverse motoring, the maximum frequency (111.11Hz) is at 2V.
4.4
Motor Speed
Experiment is conducted to determine the speed of motor without load on motor. The data was collected for forward and reverse motoring by using the tachometer and unit of motor speed in rotation per minute.
Table 4.3: Result for motor speed for forward motoring Voltage(V) 1.2 1.5 2 2.5 3 3.5 4 4.58
Motor Speed (RPM) 6.82 40.3 99 158 207.3 268 268 268
Table 4.4: Result for motor speed for reverse motoring Voltage(V) 1.2 1.5 2 2.5 3 3.5 4 4.58
Motor Speed (RPM) 6.8 40.3 99 122.3 122.6 122.6 122.6 122.6
23
Motor Speed vs Voltage Applied
Motor Speed (RPM) 300 250 200 150
Forward Motoring
100
Reverse Motoring
50 0 1.2
1.5
2
2.5
3
3.5
4
4.58
Volatge Applied (V)
Figure 4.4: Motor speed vs voltage applied
From the results, the characteristics of motor speed vs voltage applied for both forward and reverse motoring is obtained. For forward motoring, the maximum speed will reach to 268 rpm. The result shows that the speed is similar what is given from data sheet given for no-load test. Meanwhile reverse motoring will reach maximum speed (122.6rpm) at 3V.
4.5
Phase Currents
Experiment is conducted in order to determine the relationship between phase currents and voltage applied. The data of phase currents was collected for both forward reverse motoring by using current probe.
24
Figure 4.5: Phase current
Table 4.5: Result for phase current for forward motoring Voltage(V) 1.2 1.5 2 2.5 3 3.5 4 4.58
Current(A) 0.4 0.72 0.8 0.88 0.96 1.04 1.12 1.12
Table 4.6: Result for phase current for reverse motoring Voltage(V) 1.2 1.5 2 2.5 3 3.5 4 4.58
Current(A) 0.4 0.72 0.8 0.8 0.8 0.8 0.8 0.8
25
Phase Current (A)
Phase Current vs Voltage Applied
0.6 0.5 0.4 0.3
Forward Motoring
0.2
Reverse Motoring
0.1 0 1.2
1.5
2
2.5
3
3.5
4
4.58
Voltage Applied(v)
Figure 4.6: Phase current vs voltage applied
From the results, the phase current waveform for forward motoring is higher as compared to the reverse motoring. For forward motoring it will reach maximum phase current (1.12A) at 4V. Meanwhile reverse motoring will reach maximum phase current (0.8A) at 2V.
4.6
Pedal Potentiometer
The potentiometer need to be set to match the starting position of the knob. 50kΩ potentiometer is used in this project. BLDC motor start running at 1.2V, therefore the starting position value: 1.2V/5V*50kΩ = 12kΩ The mechanical travel for standard potentiometer is up to 300°. The mechanical travel of knob potentiometer can only achieved up o 32kΩ due to the limitation of pedal potentiometer rotation; where it can only achieved slightly below than maximum speed.
26
Figure 4.7: Pedal potentiometer
4.7
Integrate Complete Circuit of Go-Kart
For this part, all connection wire from output controller is well organized in black box. In the black box, there OFF switch, forward and reverse switch, 5V switch and speedometer. The series connection of lead acid battery had been connected 12V*4 = 48V. One tiny hole is drilled on the steering wheel to place the push button switch for breaking purposes.
PUSH BUTTON TO BRAKE
Figure 4.8: Integrated circuit
27
Figure 4.9: Black box
28
4.8
Working Progress
Figures below showed the working progress until completion of the electric go-kart designing.
(a) Chassis
(b) Chassis after grinded
(d) Mounted seat and steering
(e) Integrated all circuit
(c) Mounted motor
(f) Complete designed with pedal
(g) Complete go-kart assemble Figure 4.10: (a) Chassis (b) Chassis after grinded (c) Mounted motor (d) Mounted seat and steering (e) Integrated all circuit (f) Complete designed with pedal (g) Complete go-kart assemble
CHAPTER 5
CONCLUSION AND RECOMENDATION
5.1
Conclusion
An electric go-kart propulsion system, consisting of BLDC motors driven by the controller has been developed in this project. There are lots of processes in developing a complete electric go-kart, which are the understanding of BLDC motor operation, designing, implementing and testing of integrated circuit.
After finished taking all the data in this experiment, it is suit with the data sheet of BLDC motor “BM142HQ1000W48V” given from manufacturer. The voltage regulator also has been designed. It will turn 12V input voltage from lead acid battery to a fixed 5V output voltage and used to supply to regulator output from BLDC controller.
All the parts of the electric Go-Kart were integrated including the designed accelerator pedal, steering system assembly, mounted motor, mounted seat, installed lead acid battery and complete wiring circuit.
It can be concluded that the design and the development of the electric gokart is possible and achievable with the proper timeframe and equipment. This project has archived the objectives.
30
5.2
Recommendations
There are several problem encountered in this project. Since the velocity of go-kart (v = 3.87rps x 2 r) is related to the radius size of tire go-kart(r), the velocity of the go-kart can be increased by changing larger tire size. The radius of tire should be relevant to the go kart size.
The acceleration of the go-kart also depends on the load. The critical mass in this project is the mass of the battery approximately which is10kg*4battery = 40kg. By using a single battery that can supply 48 V total mass of the Go-Kart can be reduce.
The other problem is on pedal potentiometer because of the limited rotation for pedal potentiometer, the mechanical travel is only up to 32kΩ only where can achieve slightly below than maximum speed. By using special 50° potentiometer, the mechanical travel will be short so that it can achieve the maximum speed.
31
REFERENCES
[1]
Padmaraja Yedamale, Brushless DC (BLDC) Motor Fundamentals, Microchip Technology Inc.
[2]
Dynetic Systems, Brushless vs Brushed Motors, Manufacturer and Distributor of Highly Engineered Motors and Motion Control Products.
[3]
James Larminie and John Lowry, Electric Vehicle Technology Explained, John Wiley & Sons, Ltd.
[4]
Carlos Cardoso, Julio Ferreira and Virto Alves, The Design and Implementation of an Electric Go-Kart for Education in Motor Control, Faculty of Engineering of the University of Porto.
[5]
C. Fernández, O. García, J. A. Cobos,J. Uceda: Hardware and Software Environment for Self-learning in Power Electronics, 10th International Power
Electronics and Motion Control Conference, EPE-PEMC 2002
- Croatia,
September, 2002.
32
APPENDIX A
Regulator +5V Thin Red Regulator Signal Thin Green Regulator – Thin Black
A (THICK GREEN) B (THICK BLUE) C(THICK YELLOW)
POWER + Thick Red POWER - Thick Black Key Switch Thin Orange
Holl A Phase Thin Green Holl B Phase Thin Blue Holl C Phase Thin Yellow Holl Power + Thin Red Holl Power – Thin Black
Short Cut-Reverse Thin Black Thin Brown
BC424-10060
Short Cut-Brake Thin Black Thin Grey
Voltage 48V DC Power Rate 1000W Regulator 1.2-5V Phase Degree 120o Max Current 60A
Figure 1A: Digital intelligent brushless DC motor controller wiring diagram.
33
APPENDIX B
Figure 1B: Manual for BLDC motor model „BM 1424HQ‟
34
APPENDIX C 7805 Datasheet
35
36
APPENDIX D
Figure 1D: Experimental setup
UNIVERSITI TEKNOLOGI MALAYSIA DECLARATION OF THESIS / UNDERGRADUATE PROJECT PAPER AND COPYRIGHT
Author’s full name :
MOHAMMAD SYAHIM BIN KHAIRUDIN
Date of birth
:
20TH APRIL 1987
Title
:
AN ELECTRIC G0-KART USING BLDC MOTOR AS PROPULSION SYSTEM
Academic Session :
20102011/2
I declare that this thesis is classified as :
√
CONFIDENTIAL
(Contains confidential information under the Official Secret Act 1972)*
RESTRICTED
(Contains restricted information as specified by the organization where research was done)*
OPEN ACCESS
I agree that my thesis to be published as online open access (full text)
I acknowledged that Universiti Teknologi Malaysia reserves the right as follows: 1. The thesis is the property of Universiti Teknologi Malaysia. 2. The Library of Universiti Teknologi Malaysia has the right to make copies for the purpose of research only. 3. The Library has the right to make copies of the thesis for academic exchange.
Certified by :
NOTES :
SIGNATURE
SIGNATURE OF SUPERVISOR
870420-14-5257
PROF. DR. NIK RUMZI NIK IDRIS
(NEW IC NO. /PASSPORT NO.)
NAME OF SUPERVISOR
Date : 18TH MAY 2011
Date : 18TH MAY 2011
*
If the thesis is CONFIDENTAL or RESTRICTED, please attach with the letter from the organization with period and reasons for confidentiality or restriction.
“I hereby declare that I have read this project report and in my opinion this project report is sufficient in terms of scope and quality as dissertation for the Bachelor of Engineering (Electrical).”
Signature
:
_______________________________
Name of Supervisor
:
PROF. DR. NIK RUMZI NIK IDRIS
Date
:
18th MAY 2011.
PSZ 19:16 (Pind. 1/07)
AN ELECTRIC GO-KART USING BLDC MOTOR AS PROPULSION SYSTEM
MOHAMMAD SYAHIM BIN KHAIRUDDIN
Submitted to the Faculty of Electrical Engineering in partial fulfillment of the requirements for the degree of Bachelor of Engineering (Electrical)
Faculty of Electrical Engineering Universiti Teknologi Malaysia
MAY 2011
ii
I declare that this project report entitled “An Electric Go-Kart Using BLDC Motor as Propulsion System” is the result of my own research except as cited in the references. The report has not been accepted for any degree and is not concurrently submitted in candidature of any degree.
Signature
:
_________________________________________
Name
: MOHAMMAD SYAHIM BIN KHAIRUDDIN
Date
: 18th MAY 2011
iii
Dedicated to my beloved parent Khairuddin Shaari and Zainab Idris That raised and taught me to be the person I am today. Also to Prof. Dr. Nik Rumzi Nik Idris who never stop guide me and taught me everything that relate to this project. Not to forget to my family members and friends… Thank you for all your supports…….
iv
ACKNOWLEDGEMENT
Praises and thanks to Allah for giving me the opportunity to complete this project.
I would like to express my highest gratitude to my supervisor, Prof. Dr. Nik Rumzi Nik Idris for his valuable guidance and advices to complete this project. Even there are so many challenge of doing this project; he never gives up guiding me. Thank u very much sir.
Besides, I want to express my deepest thanks to Hadi Harmaini and Aswad, who always stay besides me during completing this project. They are not just a good friend, but a partner thru this project. I am also indebted to Mr. Subkhi, and Mr. Khalid who always taught us to understand more about the project. Without them, me and my partners would be lost on understanding the project.
I am also indebted to Universiti Teknologi Malaysia (UTM) particularly Faculty of Electrical Engineering (FKE) for their assistance in carrying out my project and provided accommodations to fulfill the objectives of this project.
Last but not least, a deeply appreciation are given to my family and friends for their loves, encouragement and moral support.
v
ABSTRACT
This report presents an electric go-kart are the only viable solution to replace the conventional go-kart in order to reduced air pollution, in particular, in large urban areas. A brushless direct current motor is used as propulsion system. An overview of propulsion system design and the operational of BLDC motor are presented. BLDC motors have advantages over brushed DC motors and induction motors. They have better speed versus torque characteristics, high dynamic response, high efficiency, long operating life, noiseless operation, higher speed ranges, rugged construction and so on. In addition, the voltage regulator circuit IC 7805 is use to convert from 12V from lead acid battery to constant 5V DC and supply to the regulator output from motor controller. The new designed of accelerator pedal potentiometer also has been introduced in this project. The accelerator pedal will control a potentiometer which is wired into the drive control unit to control the amount of energy flowing into the drive. The prototype has been designed specifically to meet the requirement of low cost and it contains all of the active functions required to implement the control of the go-kart.
vi
ABSTRAK
Repot ini menyampaikan go-kart elektrik adalah satu-satunya penyelesaian yang layak untuk menggantikan go-kart konvensional untuk mengurangkan pencemaran udara, khususnya, di kawasan bandar besar. Sebuah motor BLDC digunakan sebagai sistem propulsi. Ulasan tentang propulsi sistem dan operasi motor BLDC dikemukakan. Motor BLDC mempunyai kelebihan lebih dari motor DC dan motor induksi. Ianya mempunyai ciri-ciri kelajuan yang lebih baik terhadap daya kilas, respon dinamik tinggi, kecekapan tinggi, jangka hayat operasi yang panjang, pengurangan bunyi motor, rentang kelajuan yang lebih tinggi, binaan yang kukuh dan sebagainya. Selain itu, pelaras voltan IC 7805 yang digunakan untuk menukarkan dari 12V dari asid bateri ke 5V arus terus konstan dan membekalkan ke penyelarasan keluaran dari pengawal motor. Reka bentuk pedal gas perintang laras yang baru telah dikenalkan dalam projek ini. Pedal gas akan mengendalikan peringtang laras dimanna disambung kabel ke unit pemacu kawalan untuk mengawal jumlah tenaga mengalir ke dalam pemacu. Prototaip ini telah direka khusus untuk memenuhi keperluan kos rendah dan mengandungi semua fungsi aktif yang diperlukan untuk melaksanakan kawalan go-kart.
vii
TABLE OF CONTENTS
CHAPTER
1
CONTENT
PAGE
DECLARATION
ii
DEDICATION
iii
ACKNOWLEDGMENT
iv
ABSTRACT
v
ABSTRAK
vi
TABLE OF CONTENTS
vii
LIST OF FIGURES
x
LIST OF TABLES
xi
LIST OF SYMBOLS AND ABBREVIATIONS
xii
INTRODUCTION
1
1.1
Background of Project
1
1.2
Problem Statement
2
1.3
Objective of the Project
2
1.4
Scope of the Project Report
2
1.5
Project Organization
3
viii 2
3
4
LITERATURE REVIEW
4
2.1
Project Review
4
2.2
BLDC Motor
5
2.2.1
Stator and Rotor
6
2.2.2
Theory of Operation
7
2.2.3
Torque/Speed Characteristics
8
2.2.4
Commutation Sequences
9
2.3
Voltage Regulator “7805”
11
2.4
Mechanical Parts Design
12
2.4.1
Go-Kart Frame
12
2.4.2
Designed Go-Kart Parts
12
METHODOLOGY
13
3.1
BLDC Motor
13
3.2
Designed Voltage Regulator 5V
14
3.3
Designed Go-Kart Frame
15
3.4
Mounted the Motor
15
3.5
Steering System Assembly
16
3.6
Pedal Potentiometer
17
3.7
Mechanical Job Related
18
RESULTS AND DISCUSSION
19
4.1
Introduction
19
4.2
Hall Effect Sensor Phase Shift
19
4.3
Frequency Motor
20
4.4
Motor Speed
22
ix
5
4.5
Phase Currents
23
4.6
Pedal Potentiometer
25
4.7
Integrate Complete Circuit of Go-Kart
26
4.8
Working Progress
28
CONCLUSION AND RECOMENDATION
29
5.1
Conclusion
29
5.2
Recommendation
30
REFERENCES
31
Appendices A-B
32-36
x
LIST OF FIGURES
FIGURE NO.
TITLE
PAGE
2.1
Block diagram of system electric go-kart
4
2.2
BLDC motor
5
2.3
Trapezoidal motor
6
2.4
Sinusoidal motor
6
2.5
Torque/Speed characteristics
8
2.6
Winding energizing sequence with respect
9
to the hall sensor 2.7
Hall sensor signal, back EMF, output torque
10
and phase current 2.8
7805 IC voltage regulators
11
3.1
Characteristic of BLDC motor “BM142HQ1000W48V”
13
3.2
Controller wiring diagram
14
3.3
Regulate speed block diagram
14
3.4
Go-kart frame
15
3.5
Materials selection
15
3.6
Welded shaft
16
3.7
Mounted motor
16
3.8
Steering system
17
3.9
Pedal potentiometer systems
17
3.10
Mechanical job related
18
4.1
Hall Effect sensor output waveform
20
4.2
Frequency output
20
4.3
Frequency motor vs voltage applied
21
4.4
Motor speed vs voltage applied
23
xi 4.5
Phase current
24
4.6
Phase current vs voltage applied
25
4.7
Pedal potentiometer
26
4.8
Integrated circuit
26
4.9
Black box
27
4.10
(a) Chassis (b) Chassis after grinded (c) Mounted motor
28
(d) Mounted seat and steering (e) Integrated all circuit (f) Complete designed with pedal (g) Complete go-kart assemble 1A
Digital intelligent brushless DC motor controller
32
wiring diagram 1B
Manual for BLDC motor model „BM 1424HQ‟
33
LIST OF TABLES
TABLE NO.
TITLE
PAGE
4.1
Result for frequency motor for forward motoring
21
4.2
Result for frequency motor for reverse motoring
21
4.3
Result for motor speed for forward motoring
22
4.4
Result for motor speed for reverse motoring
22
4.5
Result for phase current for forward motoring
24
4.6
Result for phase current for reverse motoring
24
xii
LIST OF SYMBOLS AND ABBREVIATIONS
BLDC
-
Brushless Direct Current
DC
-
Direct Current
ECF
-
Electronically Commutated Motors
EMF
-
Electromagnetic Force
PWM
-
Pulse Width Modulation
RPM
-
Rotational Per Minute
RPS
-
Rotational Per Second
xiii
LIST OF APPENDICES
APPENDIX
A
TITLE
PAGE
Digital intelligent brushless DC motor controller wiring
32
diagram
B
Manual for BLDC motor model „BM 1424HQ‟
33
C
Voltage regulator 7805 datasheet
34
D
Experimental setup
36
CHAPTER 1
INTRODUCTION
1.1
Background of Project
Nowadays, electric Go-Kart is gaining popularity in urban community. It is one of the new hobbies for the new generations. There are many methods in building the electric go kart. One of the methods is by using the Brushless DC (BLDC) motor as the propulsion system. The prototype has been designed specifically to meet the requirement of low maintenance and low noise generation.
The basic principle of Go-Kart using fuel is much the same as with the battery electric Go-Kart, but with a fuel cell or metal air battery replacing the rechargeable electric battery. The concept of the battery electric Go-Kart is essentially simple. The Go-Kart consists of an electric battery for energy storage, an electric motor, and a BLDC controller. The battery is normally recharged from mains electricity via a plug and a battery charging unit that can either be carried onboard or fitted at the charging point. The controller will normally control the power supplied to the motor, and hence the Go-Kart speed, in forward and reverse. This is normally known as a 2 quadrant controller, forwards and backwards. It is usually desirable to use regenerative braking both to recoup energy and as a convenient form of frictionless braking. When in addition the controller allows regenerative braking in forward and reverse directions it is known as a 4 quadrant controller. There is a range of
electric
vehicles
of
this
type
currently
available
on
the
market.
2
Four-quadrant converter is used to control the DC motor drives that require forward and reverse motoring as well as forward and reverse breaking.
1.2
Problem Statement
Although riding the Go-Kart seems to be the „in‟ thing for now, but most people are unaware of the consequences riding the conventional ones. There are several disadvantages of using Conventional Go-Kart. It needs regular maintenance by spending money on fuel gas and engine oil. Although during repairing Conventional Go-Kart it is too oily and the engine too noisy during generation. It is not suitable too repair it at the house cause of neighborhoods living surround. During playing the Conventional Go-Kart, the smoke that come from the exhaust will make air pollution. This project „Electric Go-Kart‟ by using BLDC motor is the recommended system to help prevent the disadvantages of using conventional ones.
1.3
Objectives of the Project
The objectives of this project are as listed below: 1. To learn and identify operation of BLDC Motor and Controller. 2. To design the complete circuit of Go-Kart including, accelerator paddle, steering, brake, and Go-Kart frame.
1.4
Scopes of the Project
1. Study, investigate and understand the BLDC motor. 2. Design a accelerate paddle in order to measure the speed. 3. Integrate complete circuit of Electric Go-Kart 4. Conduct experiment in Energy Conversion Lab.
3
1.5
Project Organization
This thesis consists of five chapters. In the first chapter, it discuss about the objective and scope of this project as long as summary of works. While Chapter 2 will discuss more on theory and literature reviews that have been done. It well discusses about the operation and construction principle, torque/speed characteristic and commutation sequence. In Chapter 3, the discussion will be on the research methodology implementation of this project. It is consisting in two parts, electronic designed and mechanical designed. The result and discussion will be presented in Chapter 4. The results discussed in this chapter were obtained by conducted experiment to analyze and identified the output of motor such as Hall Effect sensor phase shift, frequency motor, speed of motor and phase current. Last but not least, Chapter 5 discusses the conclusion and recommendation of this project.
CHAPTER 2
LITERATURE REVIEW
2.1
Project Review
The project is divided into three sections, which are BLDC Motor and Controller, Rechargeable Batteries, and speed measurement. This project is responsible for the first section. BLDC Motor is one of the motor types rapidly gaining popularity because of its have many advantages. This section will identify and learn the operation of BLDC Motor and the connections of the controller to create accelerate paddle in order to measure the speed. Another responsibility is to create a circuit that can supply 5V constantly to the controller and design complete circuit of go-kart.
Figure 2.1: Block diagram of system electric go-kart
5
2.2
BLDC Motor
Brushless direct current motors (BLDC motors) also known as ECM (electronically commutated motors) are synchronous electric motors generated by Direct Current electricity and having electronic commutation systems, rather than mechanical commutators and brushes.[2] It is uses a permanent magnet external rotor, three phases of driving coils, one or more Hall Effect devices to sense the position of the rotor, and the associated drive electronics. They act as three-phase synchronous motors containing their own variable frequency drive electronics where the coils are activated, one phase after the other, by the drive electronics as cued by the signals from the Hall Effect sensors. BLDC motors have many advantages over brushed DC motors and induction motors. There are, low cost of maintenance due to absence of brushes, simple and inexpensive control, and noiseless operation.
BLDC motors are synchronous motor because of magnetic field generated by the stator and the magnetic field generated by the rotor rotates at the same frequency. BLDC motors do not have the “slip” that is normally seen in induction motors.
Figure 2.2: BLDC motor
6
2.2.1
Stator and Rotor
The stator of a BLDC motor consists of stacked steel laminations with windings placed in the slots that are axially cut along the inner side-line. They have three stator windings with star connection in most of BLDC motor. Each of these winding are build with plentiful of coils interconnected to form a winding and many coils are placed in the slots and they are interconnected to make a winding where will distributed even numbers of poles. There are two types of stator windings alternatives, trapezoidal and sinusoidal motors. Advantages of using sinusoidal motors, the torque output smoother than that of a trapezoidal motor. However, this comes with an extra cost, as the sinusoidal motors take extra winding interconnections because of the coils distribution on the stator periphery, thereby increasing the copper intake by the stator windings. That will make trapezoidal more cheaply than sinusoidal motors. [1]
Since the rotor is made of permanent magnet, it can vary from two to eight pole pairs with alternate North (N) and South (S) poles. There are two types of magnetic material use in BLDC motor, there are Ferrite Magnets and Alloy Magnets. The ferrite magnets are inexpensive but they have the disadvantage of low flux density for a given volume. Compare to the alloy material has high magnetic density per volume and enables the rotor to compress further for the same torque. In addition, these alloy magnets improve the size-to-weight ratio and give higher torque for the same size motor using ferrite magnets.
Figure 2.3: Trapezoidal motor
Figure 2.4: Sinusoidal motor
7
2.2.2
Theory of Operation
Stator windings should be energized in a sequence in order to rotate the BLDC motor. Identify the rotor position in order to understand which winding will be energized following the energizing sequence is very importance. Rotor position is sensed using Hall Effect sensors. Whenever the rotor magnetic poles pass near the Hall sensors, they give a high or low signal (1 or 0), indicating the N or S pole is passing near the sensors. The sequence of commutation can be determined based on the combination of three Hall sensor signals. There have two type of phase shift of The Hall Sensors, 60° or 120° phase shift to each other. Each commutation sequence has one of the windings energized to positive power where current enters into the winding and exits as negative on the second winding while the third is in a nonenergized condition. The interaction between the magnetic field generated by the stator coils and the permanent magnets (rotor) will produce torque.[1]
8
2.2.3
Torque/Speed Characteristics
The motor can be loaded up to the rated torque during continuous operation. The torque will remain constant for a speed range until the rated speed. After that the torque will start dropping in order to run up the motor to 150% of the rated speed (maximum speed).The motor need more torque than the rated for application acceleration and deceleration. During acceleration and motor starts from standstill, extra torque is required to overcome the inertia of the load and the rotor itself. As long as it follows the speed torque curve, the motor can deliver a higher torque, maximum up to peak torque.
Figure 2.5: Torque/Speed characteristics
9
2.2.4
Commutation Sequences
One of the Hall sensors changes the state and it takes six steps to complete an electrical cycle in every 60 electrical degrees of rotation and also the phase current switching will be updated. Rotor pole pairs will determine the number of electrical cycles to be repeated to complete a mechanical rotation. It means for each rotor pole pairs is equal to one electrical cycle is completed. So, the number of electrical cycles/rotations equals the rotor pole pairs. To vary the speed, these signals of PWM should at a much higher frequency than the motor frequency, at least 10 times that of the maximum frequency of the motor. [3] When the average of voltage supplied to the stator reduces, the speeds will reduce if only the duty cycle of PWM is varied within the sequences,
Figure 2.6: Winding energizing sequence with respect to the hall sensor
10
Figure 2.7: Hall sensor signal, back EMF, output torque and phase current
11
2.3
Voltage Regulator “7805”
IC Regulator 7805 is a positive voltage regulator, used to produce fixed voltage regulation. It can supply output currents until 1A when used with suitable heat sink. The last two number (78“05”) shows the value of output voltage regulation. So that it will produce fixed 5V output voltage. It can take a higher DC voltage and turn it into constant 5V DC. It needs input voltage at least 2V higher than 5V output voltage and not more than 30V input voltage. The capacitors connected to voltage regulator are optional, but it will make output voltage smoother.
Figure 2.8: 7805 IC voltage regulators
12
2.4
Mechanical Parts Design
An Electric Go-Kart is a small vehicle with simple design. It consists of small body build, four wheels, paddle potentiometer, brake and an electric motor. A lot of time is spent to build it has to be performed seriously. The important things is to take seriously in building an electric go-kart which requires time, special tools, dedication, and money.
2.4.1
Go-Kart Frame
There are two type of steel for the go-kart frame: 1. Round Pipe - Pipe steel on a go-kart looks organized but it is harder to maneuver and weld together. 2. Angular Square - Square steel is easier to bend or join and it‟s cheaper, but not so good to look at.
2.4.2
Designed Go-Kart Parts
The first step to be considered in assembling go-kart frame is to design first and always measure the steel materials twice and noted it to make sure that the particular length is right. Never use welded pieces for the main supporting parts. Be sure to measure the length and width before welding each piece.
CHAPTER 3
METHODOLOGY
3.1
BLDC Motor
In this project, BLDC Motor model “BM142HQ1000W48V” was used. The specifications were given from manufactured. It also comes with the controller.
Figure 3.1: Characteristic of BLDC motor “BM142HQ1000W48V”
14
Voltage 48V DC Power Rate 1KW Regulator 1.2-5V Phase Degree 120° Max Current 60A Figure 3.2: Controller wiring diagram
3.2
Designed Voltage Regulator 5V
The purpose of creating the voltage regulator circuit is to maintain a constant 5V level and supply it to regulator speed output from BLDC Motor Controller. Input voltage for voltage regulator is 12V from Lead Acid Battery. The range of speed to be regulated is starts from 1.2V to 5V. Actually the voltage is to control the current field flow inside the motor. Then torque has been developed from current field. This is on how the speed of the motor can be regulated. The capacitor is connected to the voltage regulator to in order to obtain a smoother output. The potentiometer 50kΩ is connected to the output voltage regulator to regulate the speed.
Figure 3.3: Regulate speed block diagram
15
3.3
Designed Go-Kart Frame
The go-kart frame had been grinded and altered to make it more presentable. All size and type of steel needed to build the parts of go-kart has been listed down before welding each piece of it. Use support to get proper height and ground clearance of parts to be welded. Set up the seats on the go-kart frame to get the size of frame and slots to mount the motor.
Figure 3.4: Go Kart frame
3.4
Figure 3.5: Materials selection
Mounted the Motor
To fit the engine parts into the go-kart frame, the shafts were cut in proper length and welding it back by male and female technique. The steel frames also being cut, drilled into, and welded together. This to ensure that the go kart can be performed carefully. Three solid metal plates have been designed for holding and mounted motor on go-kart frame. This will give firm results.
16
Figure 3.6: Welded shaft
3.5
Figure 3.7: Mounted motor
Steering System Assembly
Steering part on the frame has been clips with steel plate and a hole is made on steel plate to clip with bolts and nuts. The right size of nuts is being used to lock the bolts. The washer is located in between of each nut and bolt. This method is to avoid warp and wear. Steering system assembly function is to keep rear and front, wheels aligned and not hard-pressed away to each other. It will give smooth direction of go-kart with durable construction. There are other essential parts that make go-kart easy to maneuver. They are: 1. Spindles: Spindles act like axles when in the front of go-kart. Spindle is the most essential parts in steering system assembly. 2. Steering shaft: It is located between steering wheel and ends at the bottom go kart frame with pitman arm. 3. Pitman arms: It is located at the bottom of the steering shaft. Pitman arm connected to the tie rods and it will push it towards the desired direction whenever steering wheel has been turn together with steering shaft. 4. Tie rod: This part connected with the pitman arm and the spindles.
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Tie rod
Steering wheel
Steering shaft
Spindle Pitman arm
Figure 3.8: Steering system
3.6
Pedal Potentiometer
The speed of motor is controlled by the potentiometer. Therefore the gas pedal was altered to control the potentiometer which is wired into the BLDC controller to control the amount of power flowing into the motor. The tapper is used to make a trip on the knob of potentiometer so that the nut will be tied up the knob and throttle plate on the chassis. Two holes were drilled at the front and back. The first hole is to fit the potentiometer and the second hole is to tie up with the spring in order to keep the potentiometer travel back at first position whenever the paddle has been pressed. The cable stopper is designed to ensure cable can travel in a straight line as possible.
Figure 3.9: Pedal potentiometer systems
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3.7
Mechanical Job Related
There are several mechanical jobs related during the building of an electric go-kart process. There are: 1. Grinding - Process to get a smooth surface of the go-kart frame. 2. Tapping - Process to grind with a suitable angle on the metal before welding. 3. Material Selection - Process to select suitable steel needed. 4. Cutting - Process to cut a steel to get length and width needed. 5. Drilling - Process to make a hole on the plate and steel. 6. Welding - Process to join a material in order to get a strong joint.
Grinding
Tapping
Material Selection
Drilling
Welding
Cutting
Figure 3.10: Mechanical job related
CHAPTER 4
RESULTS AND DISCUSSIONS
4.1
Introduction
The results discussed in this chapter are obtained by conducting experiments by analyzing and identifying the output of motor such as Hall Effect sensor phase shift, frequency motor, speed of motor and phase current. The objective is to test the output result whether it is the same with the specifications given by the manufacturer. The speed of the motor can be achieved from zero to maximum speed is being discovered by testing on the design of the pedal potentiometer. With these processes, it can determine and distinguish on the successfulness of the project‟ objectives.
4.2
Hall Effect Sensor Phase Shift
In this part, experiment is conducted to determine the phase shift motor. The phase difference between of two hall sensor output had been tested. Below are the results captured by using two different hall sensor output.
1 cycle = 12ms 1 cycle = 360° Different shift between green and blue output = 4ms (4ms/12ms*360°) = 120° phase degree different
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Figure 4.1: Hall Effect sensor output waveform
4.3
Frequency Motor
The experiment in determining the frequency of the motor had also been conducted. The data of motor frequency from Hall Effect sensor output waveform for forward and reverse motoring was collected. Voltmeter is used to check on the output voltage regulator from BLDC controller. The output of Hall Effect sensor started to run at 1.2V; in which the result is the same with data sheet given by the manufacturer.
Figure 4.2: Frequency output
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Table 4.1: Result for frequency motor for forward motoring Voltage(V) Time(ms) Frequency(Hz)=1/T 1.2 170 5.88 1.5 20 50 2 11 91 2.5 7 142.85 3 5.5 181.81 3.5 4.5 222.22 4 4.5 222.22 4.58 4.5 222.22
Table 4.2: Result for frequency motor for reverse motoring Voltage(V) Time(ms) Frequency(Hz)=1/T 1.2 170 5.88 1.5 20 50 2 11 100 2.5 7 111.11 3 5.5 111.11 3.5 4.5 111.11 4 4.5 111.11 4.58 4.5 111.11
Frequency Motor(Hz)
Frequency Motor vs Voltage Applied
250 200 150 100 Reverse Motoring
50 0 1.2
1.5
2
2.5
3
3.5
4
4.58Voltage Applied (v)
Figure 4.3: Frequency motor vs voltage applied
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From the results obtained, it can be conclude that the BLDC motor starts to turn when the voltage regulator is adjusted to 1.2V. The frequency of output Hall Effect sensor for forward motoring is higher than reverse motoring. The relationship between frequency motor and regulated voltage is linear until it reaches the maximum frequency. For forward motoring, the maximum frequency (222.22Hz) is reached at 3.5V. Meanwhile for reverse motoring, the maximum frequency (111.11Hz) is at 2V.
4.4
Motor Speed
Experiment is conducted to determine the speed of motor without load on motor. The data was collected for forward and reverse motoring by using the tachometer and unit of motor speed in rotation per minute.
Table 4.3: Result for motor speed for forward motoring Voltage(V) 1.2 1.5 2 2.5 3 3.5 4 4.58
Motor Speed (RPM) 6.82 40.3 99 158 207.3 268 268 268
Table 4.4: Result for motor speed for reverse motoring Voltage(V) 1.2 1.5 2 2.5 3 3.5 4 4.58
Motor Speed (RPM) 6.8 40.3 99 122.3 122.6 122.6 122.6 122.6
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Motor Speed vs Voltage Applied
Motor Speed (RPM) 300 250 200 150
Forward Motoring
100
Reverse Motoring
50 0 1.2
1.5
2
2.5
3
3.5
4
4.58
Volatge Applied (V)
Figure 4.4: Motor speed vs voltage applied
From the results, the characteristics of motor speed vs voltage applied for both forward and reverse motoring is obtained. For forward motoring, the maximum speed will reach to 268 rpm. The result shows that the speed is similar what is given from data sheet given for no-load test. Meanwhile reverse motoring will reach maximum speed (122.6rpm) at 3V.
4.5
Phase Currents
Experiment is conducted in order to determine the relationship between phase currents and voltage applied. The data of phase currents was collected for both forward reverse motoring by using current probe.
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Figure 4.5: Phase current
Table 4.5: Result for phase current for forward motoring Voltage(V) 1.2 1.5 2 2.5 3 3.5 4 4.58
Current(A) 0.4 0.72 0.8 0.88 0.96 1.04 1.12 1.12
Table 4.6: Result for phase current for reverse motoring Voltage(V) 1.2 1.5 2 2.5 3 3.5 4 4.58
Current(A) 0.4 0.72 0.8 0.8 0.8 0.8 0.8 0.8
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Phase Current (A)
Phase Current vs Voltage Applied
0.6 0.5 0.4 0.3
Forward Motoring
0.2
Reverse Motoring
0.1 0 1.2
1.5
2
2.5
3
3.5
4
4.58
Voltage Applied(v)
Figure 4.6: Phase current vs voltage applied
From the results, the phase current waveform for forward motoring is higher as compared to the reverse motoring. For forward motoring it will reach maximum phase current (1.12A) at 4V. Meanwhile reverse motoring will reach maximum phase current (0.8A) at 2V.
4.6
Pedal Potentiometer
The potentiometer need to be set to match the starting position of the knob. 50kΩ potentiometer is used in this project. BLDC motor start running at 1.2V, therefore the starting position value: 1.2V/5V*50kΩ = 12kΩ The mechanical travel for standard potentiometer is up to 300°. The mechanical travel of knob potentiometer can only achieved up o 32kΩ due to the limitation of pedal potentiometer rotation; where it can only achieved slightly below than maximum speed.
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Figure 4.7: Pedal potentiometer
4.7
Integrate Complete Circuit of Go-Kart
For this part, all connection wire from output controller is well organized in black box. In the black box, there OFF switch, forward and reverse switch, 5V switch and speedometer. The series connection of lead acid battery had been connected 12V*4 = 48V. One tiny hole is drilled on the steering wheel to place the push button switch for breaking purposes.
PUSH BUTTON TO BRAKE
Figure 4.8: Integrated circuit
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Figure 4.9: Black box
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4.8
Working Progress
Figures below showed the working progress until completion of the electric go-kart designing.
(a) Chassis
(b) Chassis after grinded
(d) Mounted seat and steering
(e) Integrated all circuit
(c) Mounted motor
(f) Complete designed with pedal
(g) Complete go-kart assemble Figure 4.10: (a) Chassis (b) Chassis after grinded (c) Mounted motor (d) Mounted seat and steering (e) Integrated all circuit (f) Complete designed with pedal (g) Complete go-kart assemble
CHAPTER 5
CONCLUSION AND RECOMENDATION
5.1
Conclusion
An electric go-kart propulsion system, consisting of BLDC motors driven by the controller has been developed in this project. There are lots of processes in developing a complete electric go-kart, which are the understanding of BLDC motor operation, designing, implementing and testing of integrated circuit.
After finished taking all the data in this experiment, it is suit with the data sheet of BLDC motor “BM142HQ1000W48V” given from manufacturer. The voltage regulator also has been designed. It will turn 12V input voltage from lead acid battery to a fixed 5V output voltage and used to supply to regulator output from BLDC controller.
All the parts of the electric Go-Kart were integrated including the designed accelerator pedal, steering system assembly, mounted motor, mounted seat, installed lead acid battery and complete wiring circuit.
It can be concluded that the design and the development of the electric gokart is possible and achievable with the proper timeframe and equipment. This project has archived the objectives.
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5.2
Recommendations
There are several problem encountered in this project. Since the velocity of go-kart (v = 3.87rps x 2 r) is related to the radius size of tire go-kart(r), the velocity of the go-kart can be increased by changing larger tire size. The radius of tire should be relevant to the go kart size.
The acceleration of the go-kart also depends on the load. The critical mass in this project is the mass of the battery approximately which is10kg*4battery = 40kg. By using a single battery that can supply 48 V total mass of the Go-Kart can be reduce.
The other problem is on pedal potentiometer because of the limited rotation for pedal potentiometer, the mechanical travel is only up to 32kΩ only where can achieve slightly below than maximum speed. By using special 50° potentiometer, the mechanical travel will be short so that it can achieve the maximum speed.
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REFERENCES
[1]
Padmaraja Yedamale, Brushless DC (BLDC) Motor Fundamentals, Microchip Technology Inc.
[2]
Dynetic Systems, Brushless vs Brushed Motors, Manufacturer and Distributor of Highly Engineered Motors and Motion Control Products.
[3]
James Larminie and John Lowry, Electric Vehicle Technology Explained, John Wiley & Sons, Ltd.
[4]
Carlos Cardoso, Julio Ferreira and Virto Alves, The Design and Implementation of an Electric Go-Kart for Education in Motor Control, Faculty of Engineering of the University of Porto.
[5]
C. Fernández, O. García, J. A. Cobos,J. Uceda: Hardware and Software Environment for Self-learning in Power Electronics, 10th International Power
Electronics and Motion Control Conference, EPE-PEMC 2002
- Croatia,
September, 2002.
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APPENDIX A
Regulator +5V Thin Red Regulator Signal Thin Green Regulator – Thin Black
A (THICK GREEN) B (THICK BLUE) C(THICK YELLOW)
POWER + Thick Red POWER - Thick Black Key Switch Thin Orange
Holl A Phase Thin Green Holl B Phase Thin Blue Holl C Phase Thin Yellow Holl Power + Thin Red Holl Power – Thin Black
Short Cut-Reverse Thin Black Thin Brown
BC424-10060
Short Cut-Brake Thin Black Thin Grey
Voltage 48V DC Power Rate 1000W Regulator 1.2-5V Phase Degree 120o Max Current 60A
Figure 1A: Digital intelligent brushless DC motor controller wiring diagram.
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APPENDIX B
Figure 1B: Manual for BLDC motor model „BM 1424HQ‟
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APPENDIX C 7805 Datasheet
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APPENDIX D
Figure 1D: Experimental setup
