Regenerative Braking System (RBS): Energy Measurement

LOI WEI CHEONG

This report submitted in partial fulfillment of the requirements for the award

of a Bachelor Degree in Mechanical Engineering (Automotive)

Mechanical Engineering Faculty

University Technical Malaysia Melaka

JUNE 2012

SUPERVISORS DECLARATION

I hereby declare that I have read this report and in my opinion this report is sufficient

in term of scope and quality for the award of the degree of Bachelor of Mechanical

Engineering (Automotive)

Signature :

1ST Supervisor : DR.MUSTHAFAH BIN MOHD TAHIR

Date :

ii

DECLARATION

I hereby declare that the work in this report is my own except for summaries and

quotations which have been duly acknowledged.

Signature :

Author : LOI WEI CHEONG

Date :

iii

DEDICATION

To my parents, who have never failed to give me financial and moral support, for

fulfilling my need during the time of developing myself and for teaching me that

even the largest task can be accomplished if it is done one step at a time.

To my brother, sisters and friends whose indirectly contribute to this thesis.

iv

ACKNOWLEDGEMENT

First and foremost, I would like to thank my supervisor of this project,

Dr.Musthafah Bin Mohd Tahir for his valuable guidance and advice. He inspired me

greatly to work on this project. His willingness to motivate and spend his valuable

time for me is the biggest contributions to my project. I would also like to thank him

for providing me some basic information related to my topic at the very beginning of

this project.

Besides, I would like to thank University Technical Malaysia Melaka (UTeM)

for providing me a good environment and great facilities to conduct my PSM 1.

Addition, I would like to thank to the Faculty of Mechanical Engineering (FKM) for

their guidance, starting from PSM 1 subject registration until the final presentation of

my PSM. A special thank to my presentation panels, Dr. Noreffendy and En. Faizul

for their attending and judging, and provide me some important information

regarding to this project.

Finally, an honourable mention goes to our families and friends for their

understandings and supports on me in completing this project.

v

ABSTRACT

Regenerative Braking System (RBS) is an efficient system to reduce vehicle

emission and fuel consumption. RBS is a system which converts mechanical energy

to electrical energy during braking action. It will become an important system for

future vehicle such as hybrid and electric car. This study will start with literature

review about the Regenerative Braking System (RBS). The basic design and

components used in the regenerative braking for current vehicles will also be

reviewed. Through the study, a RBS model can be design or develop for future study.

The working mechanism was studied to understand how the RBS could convert

mechanical energy to electrical energy. The important components used in RBS will

be determined such as electric motor, motor controller and battery. To produce a

RBS model, an e-bike conversion kit has been bought from Hong Kong and an

alternator was selected to be installed in the bicycle. The results and calculations

show that both devices can function properly, that means both devices can form

recovery energy to charge battery during braking. During the recovery energy

working, brake effects are formed to decelerate the bike. The recovery energy during

braking for both devices are taken and compared to found out which one can produce

high recovery energy during braking. In addition this RBS model can be used for

future study.

vi

ABSTRAK

Regenerative Braking System (RBS) adalah satu sistem yang berkesan untuk

mengurangkan pencemaran kenderaan dan penggunaan bahan api. RBS sistem

menukar tenaga mekanikal kepada tenaga elektrik semasa tindakan brek. Ia akan

menjadi satu sistem yang penting bagi kenderaan masa depan seperti kereta hibrid

dan elektrik. Kajian ini akan bermula dengan kajian literatur mengenai Regenerative

Braking System (RBS). Reka bentuk asas dan komponen-komponen yang digunakan

dalam regenerative brek bagi kenderaan semasa juga akan dikaji semula. Melalui

kajian ini, model RBS boleh direka bentuk atau dibangunkan untuk kajian masa

depan. Mekanisme kerja telah dikaji untuk memahami bagaimana RBS boleh

menukar tenaga mekanikal kepada tenaga elektrik. Komponen penting yang

digunakan dalam RBS ditentukan seperti motor elektrik, motor controller dan bateri.

Untuk menghasilkan model RBS, kit penukaran e-basikal telah dibeli dari Hong

Kong dan satu alternator dipilih untuk memasang ke atas basikal. Keputusan dan

pengiraan menunjukkan bahawa kedua-dua peranti boleh berfungsi dengan baik, ini

bermakna kedua-dua peranti boleh membentuk pemulihan tenaga untuk mengecas

bateri semasa brek. Semasa kerja pemulihan tenaga, kesan brek dihasilkan dan

menyahpecutkan basikal. Tenaga pemulihan semasa brek untuk kedua-dua peranti

diambil dan membandingkan untuk mendapat tahu yang mana satu boleh

menghasilkan tenaga pemulihan yang tinggi semasa brek. Model RBS ini boleh

digunakan untuk kajian pada masa akan datang.

vii

CONTENTS

CHAPTER TITLE PAGES

DECLARATION ii

DEDICATION iii

ACKNOWLEDGEMENT iv

ABSTRACT v

ABSTRAK vi

CONTENTS vii

LIST OF TABLES xi

LIST OF FIGURES xii

LIST OF SYMBOLS xiv

LIST OF ABBREVIATION xv

LIST OF APPENDIX xvi

CHAPTER I INTRODUCTION 1

1.1 Project Introduction 1

1.2 Background 2

1.3 Objective 3

1.4 Scope 3

1.5 Problem Statement 3

CHAPTER II LITERATURE REVIEW 5

2.1 Introduction of Regenerative Braking

System (RBS) 5

2.2 RBS as Future Solution 7

2.3 Energy Efficiency for RBS 8

2.4 Type of RBS 9

viii

CHAPTER TITLE PAGES

2.5 Energy Storage System 11

2.6 How RBS Works 12

2.7 Fuel Economy 13

2.8 Maximize Energy Recovery in RBS 13

2.9 Effect Of RBS On The Stability Of The

Vehicle 14

2.10 Main components in RBS 14

2.11 Alternator 21

2.12 Voltage Rectifier 23

2.13 Voltage Regulator 25

CHAPTER III METHODOLOGY 27

3.1 Project Overview 27

3.2 Project General Flow 27

3.3 Gantt Chart for PSM 1 & 2 29

3.4 Stage 1: Research Method 30

3.5 Stage 2: Prototype Design Stage

(Identifying Components) 31

3.6 Stage 3 Components Selection 33

3.7 Stage 4: Components Purchasing 37

3.8 Stage 5: Components Installation 38

3.9 Stage 6: Engineering Drawing 44

3.10 Stage 7: Model Testing and Analyzing 49

CHAPTER IV RESULTS 54

4.1 CAD Drawing 54

4.2 Items Purchasing 55

4.3 Model build-up 58

4.4 Functional Testing and Analysis 60

CHAPTER V DISCUSSION 66

ix

CHAPTER VI CONCLUSION AND RECOMMENDATION 67

REFERENCES 70

APPENDIX 78

x

LIST OF TABLES

NO. TITLE PAGES

2.1 Comparison between conventional, series hybrid, parallel hybrid and fuel cell

vehicle. ............................................................................................................. 7

2.2 Input and output vehicle parameters obtained from NREL’s ADVISOR

simulations. ...................................................................................................... 9

2.3 Working principle of Electric Motor (EM) ..................................................... 16

2.4 Comparison between large electrolytic capacitor, Ultracapacitor paralleled

with electrolytic capacitor and DC/DC controlled ultracapacitor module. .... 20

3.1 Gantt chart for PSM 1 ..................................................................................... 29

3.2 Gantt chart for PSM 2 ..................................................................................... 29

3.3 Type of classification of alternator ................................................................. 34

3.4 Comparison of batteries .................................................................................. 35

3.5 Purchased Items .............................................................................................. 39

3.6 Example of functions used to develop 3D product in CATIA ........................ 48

3.7 Testing apparatus ............................................................................................ 50

4.1 Parts drawing ................................................................................................... 54

4.2 Total spending for the project ......................................................................... 57

4.3 Model before and after installation ................................................................. 58

4.4 Unit converts ................................................................................................... 62

4.5 Single lead-acid battery specification ............................................................. 63

4.6 Results for the 24V generator and 12V alternator 65

xi

LIST OF FIGURES

NO. TITLE PAGES

1.1 24V generator (previous work) 2

1.2 12V alternator (current work) 2

2.1 Regenerative Braking System (RBS) ............................................................... 5

2.2 Energy conversion in RBS ............................................................................... 6

2.3 Toyota Prius ..................................................................................................... 6

2.4 Honda Insight ................................................................................................... 7

2.5 Energy flow for various vehicle configurations. .............................................. 8

2.6 Series regenerative braking ............................................................................ 10

2.7 Parallel regenerative braking.......................................................................... 10

2.8 Toyota Prius battery ....................................................................................... 11

2.9 Honda Insight battery ..................................................................................... 11

2.10 Flywheel storage system (KERS) .................................................................. 12

2.11 Regenerative Braking System (RBS) ............................................................. 12

2.12 Configuration of series hybrid electric vehicle .............................................. 15

2.13 Configuration of parallel hybrid vehicle ........................................................ 15

2.14 Toyota Prius inverter ...................................................................................... 17

2.15 Honda Insight inverter.................................................................................... 18

2.16 ZEBRA battery............................................................................................... 19

2.17 Stator .............................................................................................................. 22

2.18 Rotor ............................................................................................................... 22

2.19 Diode .............................................................................................................. 22

2.20 Voltage rectifier ............................................................................................. 24

2.21 Voltage regulator ............................................................................................ 26

3.1 Flow chart ...................................................................................................... 28

3.2 Parallel hybrid electric vehicle (PHEV) layout .............................................. 31

xii

3.3 Alternator ....................................................................................................... 32

3.4 Switch ............................................................................................................. 32

3.5 Battery ............................................................................................................ 32

3.6 Regenerative braking layout structures .......................................................... 33

3.7 Components layout ........................................................................................ 38

3.8 Second hand 12V battery ............................................................................... 38

3.9 Tools needed .................................................................................................. 41

3.10 Install primary support ................................................................................... 41

3.11 Install secondary support................................................................................ 42

3.12 Install alternator ............................................................................................. 42

3.13 Install push-off switch .................................................................................... 43

3.14 Wiring the system .......................................................................................... 43

3.15 24V generator ................................................................................................. 45

3.16 Front light ....................................................................................................... 46

3.17 Controller ....................................................................................................... 46

3.18 Regenerative brake handle ............................................................................. 46

3.19 12V alternator................................................................................................. 47

3.20 Constraint ....................................................................................................... 47

3.21 Voltage output measurement using multi-meter ............................................ 51

3.22 Testing method for 24V generator ................................................................. 52

3.23 Testing method for 12V alternator ................................................................. 53

4.1 Purchase items location .................................................................................... 57

4.2 Result for 12V alternator ................................................................................ 60

4.3 Result for 24V generator ................................................................................ 61

xiii

LIST OF SYMBOLS

Freg = Regenerative braking Force

TEM_reg = EM available regenerative braking torque

TEM_max = EM maximum generation

TUC_max = Capacitor charging capacities

𝜂𝜂t = Transmission efficiency

r = Wheel radius

ωb = Weight factor

ω1 = Weight factor of ultracapacitor

ω2 = Weight factor of vehicle velocity

ω3 = Weight factor of Electric motor state

PGe_max = EM maximum generation power

PCh_max = Ultracapacitor maximum charging power

n2 = Motor rotational speed

i = Gear ratio

i0 = Final reduction gear ratio

P = Power

I = Current

xiv

LIST OF ABBREVIATION

AC = Alternating current

BCU = Brake control unit

CAD = Computer aided design

DC = Direct current

DOF = Degree of freedom

EECB = Emulated Engine Compression Braking

EHB = Electro hydraulic braking

EM = Electric motor

EPA = Environmental Protection Agencies

EV = Electric vehicle

FLC = Fuzzy logic control

HEV = Hybrid electric vehicle

ICE = Internal combustion engine

IM = Inductive motor

KERS = Kinetic Energy Recovery System

PHEV = Parallel hybrid electric vehicle

PM = Permanent magnet motor

RBS = Regenerative Braking System

RESS = Rechargeable Energy Storage System

RTD = Regenerative Torque Distribution

RTO = Regenerative Torque Optimization

SHEV = Series hybrid electric vehicle

SOC = State of charge

SRM = Switched reluctant motor

xv

LIST OF APPENDIX

NO. TITLE PAGES

A Gantt chart for PSM 1 ................................................................................... 78

B Gantt chart for PSM 2 ................................................................................... 78

C Series hybrid .................................................................................................. 79

D Parallel hybrid ............................................................................................... 79

E Series-parallel hybrid ..................................................................................... 79

F Right view for model ..................................................................................... 80

G Left view of model ........................................................................................ 80

1

CHAPTER I

INTRODUCTION

1.1 Project Introduction

The subject of Final Year Project (PSM), BMCU 4973 and BMCU 4983 are a

research and related scientific fields of study at the Faculty of Mechanical

Engineering (FKM) that must be provided by final year students to fulfill the

requirement of award of degree. Under this subject, every student will be supervised

by a lecturer and doing research regarded to the topic he or she has chosen. At the

end of the semester/year, students have to carry out a presentation regarded to this

project, and showing out all the result and findings of his research.

The purposes of this PSM are to train and improve a student's ability to use

knowledge and experience in related field of engineering. Students must able to carry

out research through scientific methods such as scientific research, collect and

analyze data and produce a design or product. Students must able to handle work

with minimal supervision and independently in this final year project. Students must

able to present their project work through seminars and written reports properly.

2

1.2 Background

Regenerative Braking System (RBS) in vehicle is my PSM title. My

supervisor is Dr. Musthafah bin Mohd Tahir. As we know, RBS is not new

technologies that exist at present. RBS was first used in the locomotive industry. Due

to the lack of sophisticated technological knowledge on suitable battery power

storage, therefore RBS attracted less interest and further study of this system is also

suspended. Nowadays, pollution problems and the limited fuel resources for vehicles

have made the RBS back to become an important system for future vehicles. RBS

can reduce air pollution and fuel consumption. After understanding the importance of

this RBS, which is the purpose of my PSM project will produce an RBS model for

future studies. In general, RBS is a system that can recuperate mechanical energy to

electrical energy during braking action. This system allows the vehicle kinetic energy

to be converted into electrical energy and be storage in the power storage system.

This saved energy will be used again to move the vehicle.

My final objective is to compare between DC motor and alternator which can

recuperate highest energy during braking action. So, a DC motor and alternator will

be assembled in the front tire of bicycle. The DC motor type is already been done by

the previous student. Hence, this project will start by collecting information from

literature review and then the installation of the alternator in the front tire of the

bicycle. Figure 1.1 and 1.2 show the previous work and current work.

Figure 1.1: 24V generator (previous work)

Figure 1.2: 12V alternator (current work)

3

1.3 Objective

The objectives of this PSM are:

1. To study the basic design of some regenerative braking system used in the vehicles.

2. To measure the regenerative braking energy for 24V DC motor.

3. To measure the regenerative braking energy for 12V alternator.

4. To compare the results of regenerative braking energy for 24V DC motor and 12V

alternator.

5. To evaluate an efficient system for future study.

1.4 Scope

The scopes of this PSM are covering:

1. Literature review and existing design information gathering.

2. Model making using 12V vehicle alternator.

3. Build a regenerative braking circuit for 12V alternator.

4. Draw the regenerative braking components using CATIA.

5. Do off road test to the 24V generator and 12V alternator.

1.5 Problem Statement

At the 21th century, the automotive industry has post a great challenge in

order to reduce the vehicle fuel consumption and emission, these is due to the

shortage of fuel resources and worsen air pollution problem. According to figures

released by the US Environmental Protection Agency (EPA), conventional ICE

vehicles currently contribute 40-50% of ozone, 80-90% of carbon monoxide, and 50-

60% of air toxins found in urban areas.

A study shows that, one third (21 to 24%) energy is consumed during brake.

The invention of Regenerative Braking System is viewed as a solution to these

4

problems, as it recovered wasted energy and restored to become another form of

useful energy. Although we realize the beneficial and positive effect bring by

Regenerative Braking System, but it still has its issue or problem to be solved; one of

the major problems is regarded as the suitable battery to be used in this type of

vehicle. Today, most Hybrid car batteries are one of these two types:

1. Nickel metal hydride

2. Lithium ion

Both are regarded as more environmentally friendly than lead-based batteries,

but both battery are very expensive and still can cause environmental damage due to

the toxic content.

5

CHAPTER II

LITERATURE REVIEW

2.1 Introduction of Regenerative Braking System (RBS)

Figure 2.1: Regenerative Braking System (RBS)

(Source: www.brighthub.com)

The Figure 2.1 above show the basic design for RBS. RBS is an important

and useful system to reduce the environment pollution and shortage of the fuel

resources problem. According to the conservation of energy, energy cannot be

created or destroyed but it can change the type of energy. RBS is a system which can

convert mechanical energy to electrical energy. This system is used in a vehicle to

recuperate the waste energy during braking and converting it to a useful energy for

conventional hydraulic brake vehicle. The waste energy was produced when

6

conventional brake is applied. The recuperate energy is then been saved in a power

storage for future usage.

In RBS, the DC motor is used as a generator to recover kinetic energy from

the wheel of the vehicle into electrical energy. The conventional hydraulic brake will

continue to be used as an emergency brake. Because the RBS is only able to stop the

vehicle in a relatively long distance and time. This situation would cause accident to

occur. The RBS efficiently reduces the waste energy and regenerate energy during

braking as shown in Figure 2.2.

Figure 2.2: Energy conversion in RBS

Nowadays, many modern hybrid and electric vehicles use this Regenerative

Braking System (RBS). Examples include the hybrids such as Toyota Prius (Figure

2.3) Honda Insight (Figure 2.4), and the Vectrix electric maxi-scooter.

Figure 2.3: Toyota Prius

(Source: www.fastmotoring.com)

Kinetic energy /waste

energy from wheel

Generated energy stored

in power storage

7

Figure 2.4: Honda Insight

(Source: www.en.automobile.de)

2.2 RBS as Future Solution

The need to increase environmental protection and energy conservation has

brought a big challenge for the automotive industry to reduce vehicle emissions and.

fuel consumption. For this purpose, extensive solutions for alternative power train

has been proposed, including hybrid technology is regarded as the best. Government

regulations around the world have become more stringent, requiring lower

production for the car (Especially U.S. EPA Tier 2 Bin 5, followed by a Euro 5).

In 2003, a research has been done by V. Dawood and A. Emadi in order to

compare between fuel cell, parallel & series hybrid electric and conventional transit

bus. ADVISOR software was used to simulate the various heavy-duty buses. Results

show a magnificent (as indicated in Table 2.1) improvement in the fuel economy

especially in the parallel configuration. [9]

Table 2.1: Comparison between conventional, series hybrid, parallel hybrid and fuel

cell vehicle.

(Source: V. Dawood. 2003)

Conventional Series Fuel cell Parallel

Fuel Converter(kW)

350 100 200 150

Energy storage(kW)

- 300 300 250

8

Motor(kW) - 300 250 200

Total propulsion power( kW)

350 300 250 350

Fuel Economy(mpg)/

(km/kg)

5.1 / 0.0082 7.4 / 0.0119 7.5 / 0.0121 9.3 / 0.0149

0-60 mph (s) or 0-

96.6 km/h

25.7 18.2 19.1 18.0

Grade Ability

(%)

6.0 2.5 2.3 2.5

Max. speed

(km/h)

138.4 138.9 138.7 138.1

2.3 Energy Efficiency for RBS

Demirdven, N. and Deutch, J. (2003) compare the energy efficiency of

conventional internal combustion engines, fuel cell and hybrid vehicles. In their

analysis (as indicated in Figure 2.5 and Table 2.2) indicates that fuel cell vehicles

using hydrogen from fossil fuels offer no significant energy efficiency advantage

over hybrid vehicles operating in an urban drive cycle. They conclude that priority

should be placed on hybrid vehicles by industry and government.[32]

Figure 2.5: Energy flow for various vehicle configurations.