Design and simulation the electric bus

Content of the project: Chapter 1: INTRODUCTION Chapter 2: LITERATURE SURVEY Chapter 3: ELECTRIC BUS CALCULATION AND DESIGN Chapter 4: SIMULATION AND RESULT Chapter 5: CONCLUSION 4.. 23

MINISTRY OF EDUCATION AND TRAINING

HO CHI MINH CITY UNIVERSITY OF TECHNOLOGY AND EDUCATION

FACULTY FOR HIGH QUALITY TRAINING

GRADUATION THESIS AUTOMOTIVE ENGINEERING

DESIGN AND SIMULATION THE ELECTRIC BUS

HUYNH THANH DAT

S K L 0 1 0 7 2 8

Ho Chi Minh City, July 2023

ADVISOR : M.S HUYNH QUOC VIET STUDENTS: HOANG VAN BONG

HO CHI MINH CITY UNIVERSITY OF TECHNOLOGY AND EDUCATION

FACULTY FOR HIGH QUALITY TRAINING

GRADUATION PROJECT

DESIGN AND SIMULATION THE ELECTRIC BUS

HOANG VAN BONG Student ID: 19145137

Student ID: 19145171 Major: AUTOMOTIVE ENGINEERING Advisor: HUỲNH QUỐC VIỆT, MS

Ho Chi Minh City, July 3, 2023

THE SOCIALIST REPUBLIC OF VIETNAM

Independence – Freedom– Happiness

-

Ho Chi Minh City, July 3, 2023

GRADUATION PROJECT ASSIGNMENT

Student name: Hoang Van Bong Student ID: 19145137

Student name: Huynh Thanh Dat Student ID: 19145171

Major: Automotive Engineering Class: 19145CLA

Advisor: M.S Huynh Quoc Viet

Date of assignment: 13/02/2023 Date of submission: 03/07/2023

1 Project title: DESIGN AND SIMULATION THE ELECTRIC BUS

2 Initial materials provided by the advisor:

− ADVISOR

− 5SORT-2004-ENG

− Bao-cao-esp-va-advisor

− Modern electric, hybrid electric, and fuel cell vehicles 3rd-ed

3 Content of the project:

Chapter 1: INTRODUCTION

Chapter 2: LITERATURE SURVEY

Chapter 3: ELECTRIC BUS CALCULATION AND DESIGN

Chapter 4: SIMULATION AND RESULT

Chapter 5: CONCLUSION

4 Final product:

− Model Simulation Electric Bus on ADVISOR

CHAIR OF THE PROGRAM

(Sign with full name)

ADVISOR

(Sign with full name)

THE SOCIALIST REPUBLIC OF VIETNAM

Independence – Freedom– Happiness

-

EVALUATION SHEET OF DEFENSE COMMITTEE MEMBER Student name: Hoang Van Bong Student ID: 19145137 Student name: Huynh Thanh Dat Student ID: 19145171 Major: Automotive Engineering Project title: DESIGN AND SIMULATION THE ELECTRIC BUS Name of Defense Committee Member:

EVALUATION 1 Content and workload of the project

2 Strengths:

3 Weaknesses:

4 Overall evaluation: (Excellent, Good, Fair, Poor)

5 Mark:……….(in words: )

Ho Chi Minh City, July 3, 2023

COMMITTEE MEMBER

(Sign with full name)

i

Disclaimer

I hereby declare that: The Graduation Project "DESIGN AND SIMULATION THE ELECTRIC BUS" is conducted publicly, based on my huge efforts and asist from the University of Technology and Education of Ho Chi Minh City, under the enthusiastic scientific guidance of MS Huynh Quoc Viet

The data and study results in the topic are accurate and do not copy or utilize the findings of any other research effort If a copy of the study results from another topic is found, I shall accept full responsibility

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Acknowledgements

The first word she knew that the support of my family was the inspiration and strength for her to complete her graduation project She hopes that I will be able to continue to uphold the faith and support of my family in the future and make my family proud of what she has achieved I would also like to thank the teachers and students of Ho Chi Minh City University of Technology and Education for teaching

me a lot of valuable knowledge and guiding me through many things during my studies Thanks to these, it helped me to complete the thesis well

In particular, I would like to express my sincere gratitude to Mr Huynh Quoc Viet -

Ho Chi Minh City University of Technology and Education for directly guiding, helping and creating many conditions for me in the process project implementation His knowledge and experience not only helped me to complete the topic well, but also set an example for me to study and follow in the future

Once again, I would like to thank the teachers, and wish them always happy and good health to lead the next generations to a better day

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Table of Contents

Chapter 1: INTRODUCTION 1

1.1 Reasons for choosing the topic 1

1.2 Research situation in Abroad and Vietnam 2

1.2.1 Research situation in Abroad 2

1.2.2 Research situation in Vietnam 2

1.3 Aim of Research 3

1.4 Research Method 4

1.5 Research subjects 4

1.5.1 Range of Research 4

1.5.2 Arrange of Research 4

Chapter 2: LITERATURE SURVEY 5

2.1 Overview of Electric Bus 5

2.1.1 Global Electric Vehicle Status 5

2.1.2 ASEAN electric vehicle status 6

2.1.3 Electric Vehicle in Vietnam 7

2.1.4 The Characteristic of Electric Bus 7

2.2 Bus dynamics 8

2.2.1 Vehicle Load Forces and Dynamics Equation 8

2.2.1.1 Basic Power, Energy, and Speed Relationships 9

2.2.1.2 The Rolling Resistance 9

2.2.1.3 Aerodynamic Drag 9

2.2.1.4 Climbing Resistance 10

2.2.2 Power Train Traction Effort and Vehicle Speed 11

2.2.3 Vehicle Performance 12

2.2.3.1 The maximum speed of a vehicle 12

2.2.3.2 Gradeability 13

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2.2.3.3 Acceleration Performance 13

2.2.4 Driving cycle for Vehicle 14

2.2.4.1 Driving cycle design for testing Electric Bus 14

2.2.4.2 Practical cycle construction 15

2.3 EV Charging Method 16

2.3.1 Battery Swap Station (BSS) 17

2.3.2 Wireless Power Transfer (WPT) 17

2.3.3 Conductive Charging (CC) 18

2.4 EV Charging Configuration for Electric Bus 20

Chapter 3: DESIGN AND CALCULATION OF ELECTRIC BUS 22

3.1 Available Specifications 22

3.2 Choosing Parameter 24

3.2.1 Chossing Coefficients 24

3.2.2 Chossing Auxiliaries Component 24

3.3 Calculation Parameter 25

3.3.1 Motor Parameter Calculation 25

3.3.1.1 Determination of peak power and rated power of motor 26

3.3.1.2 Determination of peak speed and rated speed 27

3.3.1.3 Determination of peak torque and rated torque 27

3.3.1.4 Choosing an Electric Motor 27

3.3.2 Battery pack sizing 30

3.3.2.1 Calculation of Power Battery Parameters 30

3.3.2.2 Identify a Bus route 32

3.3.2.3 Choosing Type of Battery 34

3.3.3 Proposed E-Bus Charging Design and Sizing 36

Chapter 4: SIMULATION AND RESULT 38

4.1 Overall about ADVISOR software 38

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4.1.1 ADVISOR Structure 38

4.1.2 Advantages of ADVISOR in simulating on vehicles 39

4.1.3 ADVISOR’s capacities 39

4.2 Configuration parameter on ADVISOR 40

4.2.1 How to set up the parameters 40

4.2.2 Load and save vehicle configuration 44

4.2.3 Viewing component information 44

4.2.4 Establish the parameters of the Electric Bus model 45

4.2.4.1 Set up the drivetrain system 45

4.2.4.2 Establish the driving cycles 52

4.3 Simulation Result 59

4.3.1 Testing vehicle performance 59

4.3.2 Simulation results 60

Chapter 5: CONCLUSION 65

5.1 Electric Bus Model 65

5.2 Suggestion for Future Work 66

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List of Figures

Figure 2.1 Forces acting on a vehicle moving uphill 8

Figure 2.2 Vehicle Motoring 11

Figure 2.3 Tractive effort and torque on a drive wheel 12

Figure 2.4 Structure of the cycles 14

Figure 2.5 Sort 1: Urban 15

Figure 2.6 Sort 2: Mixed 16

Figure 2.7 Sort 3: Suburban 16

Figure 2.8 EV Charging Methods 17

Figure 2.9 Illustration of inductive charging for buses 18

Figure 2.10 EV charging configuration for off-board 20

Figure 2.11 EV charging configuration for on-board 21

Figure 3.1 The parameter of Vinbus 22

Figure 3.2 Product Information 29

Figure 3.3 A bus route model of circular bus line 32

Figure 3.4 HAYOEN LFP battery cell 3.2V home batterie solaire lithium 280AH 35

Figure 4.1 Structure of ADVISOR 39

Figure 4.2 Vehicle component signal variables 40

Figure 4.3 View vehicle information 45

Figure 4.4 Custom load file 46

Figure 4.5 The code of Electric_Bus.in 47

Figure 4.6 Select the powertrain system 48

Figure 4.7 Choose a vehicle 49

Figure 4.8 Choose a motor 50

Figure 4.9 The window displays the parameter of the motor (1) 51

Figure 4.10 The window displays the parameter of the motor (2) 51

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Figure 4.11 Continue or Back 52

Figure 4.12 Simulation configuration setting interface 53

Figure 4.13 Edit driving cycles 54

Figure 4.14 CYC_SKELETON driving cycle 55

Figure 4.15 SORT 1 – Urban 56

Figure 4.16 SORT 2 – Mixed 57

Figure 4.17 SORT 3 – Suburban 58

Figure 4.18 Parameter running on the bench 59

Figure 4.19 Available torque out of the motor 60

Figure 4.20 Current output of the battery 61

Figure 4.21 Force achieved by the vehicle 61

Figure 4.22 The actual power loss for the energy storage system 61

Figure 4.23 Available power in the motor 62

Figure 4.24 Average temperature of the battery module 63

Figure 4.25 Average temperature of motor and controller 63

Figure 4.26 Power lost by the motor/controller 63

Figure 4.27 State of charge history 64

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List of Tables

Table 2.1 Incline angles and grade 10

Table 2.2 Summary of reviews on charging methods 19

Table 2.3 IEC and SAE standards: Current and voltage level for AC and DC charging 21

Table 3.1 Vehicle Parameters of pure Electric Bus 23

Table 3.2 Power Performance Requirements for pure Electric Vehicle 23

Table 3.3 Coefficients of Vinbus Electric Vehicle 24

Table 3.4 Power dissipation of the connecting loads continue on the car 24

Table 3.5 Power dissipation of cockroach loads section on the car 25

Table 3.6 Working load in a short time 25

Table 3.7 Specifications of APEV80-12(16) Motor 28

Table 3.8 AEV100-D540D540200L2 motor controller Specification 28

Table 3.9 Information of routes 33

Table 3.10 Specification of Electric Battery 35

Table 3.11 The energy result 37

Table 4.1 Input information of a vehicle 41

Table 4.2 Characteristics of the cycle of public transport 54

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Abstract

With the rapid development of the current electric car industry, this will be a promising solution that will bring positive changes to the current state of environmental pollution Simultaneously with that rapid change, public transport such as traditional buses are also starting a shift from traditional internal combustion engines to electric motors For example, developed countries like China and western countries, most of their public transport systems have been developed and operated entirely by electric cars Equipped with many modern technologies along with smooth operation, users will definitely prefer using electric public transport over traditional energy cars However, the process of conceptualizing and designing an electric bus will not be easy They depend on many factors such as intended use, operating requirements such as maximum speed, ability to climb slopes, acceleration, distance traveled and how long it takes to run From those basic requirements, people start to calculate and design Then select the parts that match the original calculations Finally, in order to meet the performance and life expectancy of the battery, we need to calculate the parameters to design and choose

a charger suitable for the vehicle

To carry out this topic, I have divided into main research and calculation parts:

− Select motor parameters for the vehicle based on the desired parameters and available parameters

− Calculation of energy for Batteries operating under different working conditions

− Simulate the operation of the vehicle on different distances, thereby calculating the capacity and charging time for the vehicle

Keyword: Electric Bus, ADVISOR, Electric Battery, Electric Drivetrains

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Chapter 1: INTRODUCTION

As we know, fossil fuels are the main source of fuel for vehicles using traditional engines However, this supply is gradually becoming scarcer due to high demand and limited reserves In the UK, a fuel crisis is occurring due to scarcity of fuel as well as high prices due to imports from other countries

Another cause that can affect fuel sources for vehicles is war Last year, we had to witness the highest gasoline price, mainly due to the war between Russia and Ukraine This war has a direct impact on the world economy as well as in Vietnam The increase in gasoline prices also greatly affects the demand for using traditional vehicles

The worldwide disruption created by the COVID-19 Pandemic has brought many positive impacts on the environment and climate The reduction of modern human activities on a global scale such as: a significant reduction in the need for planned travel has caused a large decrease in air pollution and water pollution in many areas When the pandemic first occurred, environmental quality gradually improved as the air became cleaner as cities imposed blockade orders or social distancing

In Vietnam, the General Department of Environment (Ministry of Natural Resources and Environment) said that comparing the results of air quality in northern cities from January 1 to April 2020, including the period of isolation Society shows that the change in production and human activities is an important cause of changing air quality Compared to the same period of previous years, air quality also tends to improve, since people have reduced unnecessary movement due to the Covid-19 epidemic, which has contributed to a significant decrease in air quality carbon dioxide, methane, and carbon monoxide emissions This also shows that the influence of emission sources such as traffic and manufacturing activities has a significant impact on urban air quality

Therefore, the application of electric vehicles to replace traditional vehicles is one

of the methods to effectively solve those problems Currently, in big cities in Vietnam are starting to research and develop electric bus models to replace old buses And Vinbus is the first car company to successfully apply its electric bus model and is applied on a number of routes in Hanoi and Ho Chi Minh City

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Realizing that this is one of the potential solutions to develop the city, our group

decided to research about the topic “DESIGN AND SIMULATION THE

ELECTRIC BUS” in order to calculate, research and check the preliminary

assessment of the simulation model of an electric bus based on the Vinbus car including available parameters From there to evaluate whether the calculated results are consistent with the parameters of the model or not, and the greatest desire from the knowledge and research in the article, this will be the basis for research and development of a complete electric bus

1.2.1 Research situation in Abroad

The Asia Pacific area has the world's largest electric bus market It is home to some

of the world's most rapidly expanding and developed economies The region's development may be ascribed to the Chinese market's dominance as well as the existence of prominent OEMs in the nation, resulting in the Asia Pacific electric bus and coach market growing at an exponential rate

The region's electric bus industry is expected to increase due to favorable legislation for electric buses, the availability of electric and electronic components, and quickly expanding charging infrastructure In January 2022, the Government of India would distribute 670 electric buses to the states of Maharashtra, Goa, Gujarat, and Chandigarh under Phase 2 of the FAME initiative Furthermore, 241 charging stations will be installed on the roads of Madhya Pradesh, Tamil Nadu, Kerala, Gujarat, and Port Blair

During the projected period, North America is predicted to be the fastest-growing market For example, the US Federal Budget pledged USD 130 million in 2019 to expedite the implementation of zero-emission buses and automobiles Blue Bird will deliver its 400th electric school bus in North America in March 2021 The business intends to deploy 1,000 electric school buses by 2022 A growing number

of such breakthroughs imply that the North American electric bus industry will increase tremendously in the future

1.2.2 Research situation in Vietnam

In Vietnam, Vinbus is the first electric bus to be operated and serve the travel needs

of people However, the current use of Vinbus is only applied to 2 big cities, Hanoi and Ho Chi Minh City In Ho Chi Minh City, most of these cars are only driven

to "zero" by 2050 The strategy sets a target that from 2025, 100% of buses will replace to invest in new electric vehicles and green energy From 2030, the rate of vehicles using electricity and green energy will reach at least 50%; 100% replacement taxi, new investment using electricity, green energy By 2050, 100% of buses and taxis will use electricity and green energy

Therefore, the race for electric buses will not stop with Vinbus alone, transport companies invested and supported by car companies like Samco and some others are also starting the research and launching process products to keep up with the current trend of electric vehicles

The primary goal of this project is to develop a comprehensive parametric design approach for the drivetrain system of an electric bus This approach may identify both the ratings and maximum capabilities of the powerplant for a given vehicle's characteristics Motor power, torque, speed, and battery capacity are all rated The ratings in the suggested approach take into account the vehicle's maximum velocity and maximum acceleration rate in order to attain the hardest road conditions The suggested methodology's validation is discussed using the case study Vinbus The cars' performance is simulated and evaluated using two distinct driving cycles

A parameter optimization technique for a medium-sized bus's power system based

on the orthogonal test and secondary development of ADVISOR software The vehicle power system characteristics were matched and created based on vehicle theoretical knowledge and the needs of the vehicle power performance index The modeling of the vehicle's essential components was completed using the secondary development of MATLAB/Simulink and ADVISOR software Considering the impact of the number of battery packs, motor power model, wheel rolling resistance coefficient, and wind resistance coefficient on the power system design The dynamic performance and driving range of the entire vehicle were simulated using several design approaches, and the quality of the simulation findings was validated

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by comparing and evaluating the simulation images The study material of this article gives a specific reference for the design of shuttle buses for the Electric Bus system, efficiently minimizes the testing costs of the vehicle development process, and provides a novel idea for the power system design of pure electric buses

− Programming language Matlab/Simulink

− ADVISOR simulation software

− Electric bus

− The driving cycle has been selected and set up

− Study the actual running routes of buses in Ho Chi Minh City

1.5.1 Range of Research

Focus on researching and calculating, designing components of an electric bus based on an existing Vinbus The range is only the routes in Ho Chi Minh City The data is only obtained through the process of calculation and analysis

1.5.2 Arrange of Research

• Chapter 1: INTRODUCTION

• Chapter 2: LITERATURE SURVEY

• Chapter 3: ELECTRIC BUS CALCULATION AND DESIGN

• Chapter 4: SIMULATION AND RESULT

• Chapter 5: CONCLUSION

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Chapter 2: LITERATURE SURVEY

2.1.1 Global Electric Vehicle Status

The global electric bus market was valued at 170 thousand units in 2020 and is predicted to grow at a CAGR of 16.0% from 192 thousand units in 2021 to 544 thousand units by 2028 According to our research, the global market will shrink by 14.1% in 2020, compared to the average year-on-year gain from 2017 to 2019 COVID-19 has had an unprecedented and catastrophic global impact, with the market seeing a severe impact on demand across all industries as a result of the pandemic The increase in CAGR is attributable to this market's demand and growth, which will return to pre-pandemic levels once the pandemic is over [1] According to the United Nations Environment Program (UNEP), city buses contribute considerably to black carbon emissions from the transportation sector As

a result, the UNEP is assisting 20 cities in Asia, Latin America, and Africa in developing and mapping low-emission public transportation networks that include e-buses Furthermore, in order to acquire public commitment, the UNEP, in partnership with the International Clean Transportation Council (ICCT) and regional partners, has given technical help to identify and eliminate hurdles, as well

as support for the adoption and design of clean buses These government initiatives are anticipated to boost the expansion of the electric bus market throughout the forecast period [1]

The covid-19 outbreak has had a substantial influence on e-bus deployments Several public transportation networks throughout the world are incurring major revenue losses as a result of the epidemic's decline in transit use According to the American Public Transportation Association (APTA), public transportation usage declined by 80% in April 2020, with passenger numbers falling by more than 60% for the rest of 2020 compared to 2019 The APTA predicts that this trend will continue in the short to medium term due to reasons such as increased remote work and an increase in private automobile ownership [1]

In Santiago, Chile, for example, there are 776 privately owned electric buses In this model, fleet owners acquire and maintain these buses before leasing them on long-term contracts to municipalities or transit providers This distinguishes operation from ownership This might pave the path for a large-scale transition to electric fleets As a result, these characteristics will influence market growth [1]

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2.1.2 ASEAN electric vehicle status

During the 33rd ASEAN summit in September 2016, member states decided to set a long-term goal of decreasing the region's greenhouse gas emissions by 20% Despite global progress in electric buses, ASEAN nations are still three to five years away from commercialization due to the high cost of components and the demand produced by a lack of know-how To fulfill the objective for greenhouse gas emissions, ASEAN countries are developing and testing a variety of prototype electric bus projects

Brunei has just lately begun importing electric buses, and Shenglong New Energy Automobile Co., Ltd., a Chinese electric vehicle manufacturer, will soon establish

an electric bus manufacturing plant in Berakas This factory will be developed in partnership with a Chinese corporation based in Guangxi and a company with ties to the Bruneian government

The University of Indonesia in Jakarta displayed four electric vehicles created by the campus engineering department in Depok, West Java The Makara Electric Vehicle (MEV) initiative includes three municipal vehicles and one electric bus [2] The Laotian government created the E-bus project and encouraged government employees to use more public electric buses, which are both economical and environmentally friendly The Japanese International Cooperation Agency (JICA) is funding the E-bus project, which is being operated by Lao Green Company in the UNESCO World Heritage town of Luang Prabang [2] [3]

Malaysia completed the first electric bus test in June 2015, and fifteen eco-buses were deployed for the Sunway Group's Bus Rapid Transit (BRT)

The Philippine government is encouraging the use of electric vehicles PhUV Inc., a local bus manufacturer, built approximately 20 electric minibuses known as e-jeepneys Several government towns, colleges, and commercial companies use e-jeepneys, including the country's electricity supplier, Manila Electric Co (Meralco), Ateneo de Manila University, and De La Salle University

Singapore has committed to reducing emissions by 7% to 11% below "business as usual" BAU levels by 2020 The GreenLite, Singapore's first hydrogen and lithium-ion battery electric bus, was developed in 2011 by Nanyang Technological University (NTU), Tsinghua University, and Shanghai Sunlong Bus Co., Ltd [2]

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2.1.3 Electric Vehicle in Vietnam

The first electric buses bearing the VinBus name have arrived in Vietnam (Vinhomes Ocean Park, Gia Lam) According to Insideevs, the automobile is built and assembled at Hai Phong's Automobile Manufacture Complex VinBus is a Vingroup subsidiary that began operations in September 2019

At the end of 2021, VinBus launched the first electric bus route in Hanoi, followed three months later by the first electric bus line in Ho Chi Minh City (HCMC) By the end of June 2022, Hanoi will have around 100 VinBus electric buses running on eight routes, HCMC will have 20 vehicles working on one route, and Phu Quoc will have 30 buses in the area

The number of VinBus in operation is small in comparison to the over 5,000 buses currently in operation in Hanoi, HCMC, and Da Nang; however, it is a significant milestone because it is Vietnam's first electric bus and the first electric bus licensed operator to provide public transportation services [4] [5]

2.1.4 The Characteristic of Electric Bus

Buses are vehicles with large wheels, similar to ordinary passenger cars However,

it has the distinction of operating on shorter routes Specifically, connecting urban points together, inter-districts, towns and cities Usually each province will have its own bus system

Buses operate most days of the week Regardless of holidays, Saturday or Sunday However, the transportation of the bus always follows a fixed time frame

Depending on the distance between urban clusters, the number of vehicles distributed in that area, the travel needs of the people But each place will have a different running frequency Usually there is one every 15 minutes In densely populated areas or peak clusters, the frequency will be 5-10 minutes On the contrary, where few people have a need to use it, it will take 20 to 30 minutes for 1 turn [6]

It is vital to select an electric motor for a bus based on its operational characteristics

in order to ensure that it meets the necessary operating criteria for an electric bus

An electric motor with the following features: high torque, low speed, and adequate properties for swift acceleration, hill climbing, and obstacle negotiating is suited for traction application in an electric bus

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We study the power and energy needs of the automobile powertrain in this section

by applying physics concepts to the vehicle's motion First, analyze the fundamental vehicle load forces of aerodynamic drag, rolling resistance, and climbing resistance This preliminary analysis allows for the quantification of a vehicle's power and energy requirements, as well as the conversion of these vehicle requirements of speed and accelerating or braking power into mechanical specifications of torque and speed for the electric motor

2.2.1 Vehicle Load Forces and Dynamics Equation

Understanding vehicle driving needs and performance criteria is necessary for developing the electric powertrain In this section, the primary load forces of Rolling Resistance (FR), Aerodynamic Drag (FD), and Climbing Resistance acting

on the vehicle (Fc), as illustrated in Figure 2.1 [7]

Figure 2.1 Forces acting on a vehicle moving uphill

The slip between tire and road provides traction force, FT, and the engine or electric motor is the true power source for slip creation For acceleration or deceleration, the difference between the total of road loads and the traction force is used The dynamic equation of vehicle motion in the longitudinal direction is expressed by:

MdV

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2.2.1.1 Basic Power, Energy, and Speed Relationships

According to [7], power is defined as work done per second The unit of power is the watt (W)

If a vehicle travels at a constant speed v, the power P required to move it is equal to the product of the force F and the speed In equation form:

2.2.1.2 The Rolling Resistance

In [7] [8], the rolling resistance is the product of all frictional load forces caused by tire deformation on the road surface and friction inside the drivetrain The following equation describes rolling resistance FR:

2.2.1.3 Aerodynamic Drag

In [7] [8], aerodynamic drag is the resistance of air to vehicle movement The vehicle's aerodynamic drag force FD and power PD are described as:

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FD =1

2ρaAfCd(v ± vw)2 (2.10) And

v + vw: vehicle and wind are travelling in same direction

v − vw: vehicle and wind are travelling in opposite direction

2.2.1.4 Climbing Resistance

Depending on [8] whether the automobile is rising or descending an elevation, the vehicle load power might rise or decrease The downhill force or climbing resistance is provided by:

The downhill force is negative and can result in energy regeneration to the battery, a mode typically utilized in electrically driven cars to slow the vehicle rather than friction braking

The gradeability of a vehicle is the highest slope that it can climb at a given speed

It is the tangent of the incline angle, or the ratio of the climb to the run

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2.2.2 Power Train Traction Effort and Vehicle Speed

A power plant (electric motor), a gearbox (transmission), final drive include differential, drive shaft, and drive wheels comprise an automobile power train, as illustrated in Figure 2.2 The gearbox, final drive, differential, and drive shaft transfer torque and rotational speed from the power plant's output shaft to the drive wheels The gearbox provides a few gear ratios from its input shaft to its output shaft to adapt the torque-speed profile of the power plant to the load requirements The final drive is often a set of gears that provide additional speed reduction and distribute torque to each wheel via the differential [7]

Figure 2.2 Vehicle Motoring

The torque on the drive wheels, transmitted from the power plant, is expressed as:

(2.17)

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Figure 2.3 Tractive effort and torque on a drive wheel

The rotating speed, in revolutions per minute (RPM), of the drive wheel can be expressed as:

2.2.3.1 The maximum speed of a vehicle

In [7] [8] [9], a vehicle's maximum speed is the highest consistent cruising speed that it can accomplish at full power on a flat road When the tractive and resistive forces are in equilibrium, the maximum speed of a vehicle is determined with full torque from the traction source on a level road:

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Then, the rated power of the traction motor Pm depends on the maximum velocity

Vmax, the total tractive force FT and it is expressed as:

2.2.4 Driving cycle for Vehicle

2.2.4.1 Driving cycle design for testing Electric Bus

Follow [10], the urbanization and traffic levels in each city, as well as the specific working environment of each transportation business, demand actual variety, and maintaining simply one "urban" cycle would be unduly simple

The structure of the cycles can be sketched as follows:

Figure 2.4 Structure of the cycles

The following need to be determined:

• The number of trapezes

• The number of base cycles

• The acceleration values

• The target speeds

• The braking values

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Number of different base cycles necessary After long discussion, 3 base cycles appear to offer a reasonable solution:

• Urban base cycle: Velocity is 12 km/h

• Mixed base cycle: Velocity is 17 km/h

• Suburban base cycle: Velocity is 27 km/h

2.2.4.2 Practical cycle construction

In [10], three different base cycles have been created to show urban traffic (SORT 1), mixed traffic (SORT 2), and suburban traffic (SORT 3) Each cycle includes an inactive time The period of standstill was changed to match the average pace of each cycle (e.g., distance vs time including stops) The stoppage % is primarily determined by actual experience

SORT 1 (Urban traffic) is extensively covered This cycle has three trapezes that move at constant rates of 20 km/h, 30 km/h, and 40 km/h After each trapezoid, a 20-second respite is provided, giving the cycle a total idle time of 60 seconds The average speed (commercial speed) of this cycle is roughly 12 km/h

Figure 2.5 Sort 1: Urban

The SORT 2 and 3 cycles consist of three basic trapezes The primary distinction between the SORT 3 cycle (suburban) and the SORT 1 and SORT 2 cycles is a shorter stop duration at each stop: 40 seconds as opposed to 60 seconds for SORT 1 and SORT 2 This is because the load has been statistically lessened

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Figure 2.6 Sort 2: Mixed

Figure 2.7 Sort 3: Suburban

The three primary charging methods are battery exchange, wireless charging, and conductive charging Figure 2.8 [11] illustrates the additional division of conductive charging into pantograph (Bottom-up and Top-down) and overnight charging

However, because the BSS owner owns the EV batteries, this type of EV charging approach may be more expensive than refilling the ICE engine due to the BSS owner's high monthly lease charges This strategy necessitates the purchase of multiple expensive batteries as well as a large storage space, which might be costly

in a congested area Furthermore, while the station may have a certain battery model, the automobiles' battery requirements may differ [15] [16]

2.3.2 Wireless Power Transfer (WPT)

This electromagnetic induction-based approach employs two coils The secondary coil is inside the automobile, while the primary coil is outside on the road WPT technology has lately sparked attention in EV applications because to its ability to

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offer convenient and secure EV charging It can even charge while the car is driving and does not require a normal connector (but does require traditional coupling technology) [17]

Because inductive power transfer is often modest, the air space between the transmitter and receiver coils should be between 20 and 100 cm for effective power transmission [18] Eddy current loss is another issue in the WPT if the transmitter coil is not turned off Communication delays are likely because real-time information transfer between the transmitter and the EV is necessary [19] Figure 2.9 [20] illustrate of inductive charging for buses

Figure 2.9 Illustration of inductive charging for buses 2.3.3 Conductive Charging (CC)

Conductive charging offers various charging capabilities, and has a high charging efficiency since it involves a direct electrical connection between the car and the charging input The two power charging levels (Level 2 and Level 3) are used for a public charging station [11]

Conductive charging provides a V2G capability, minimizes grid loss, maintains voltage, avoids grid overloading, supports active power, and may compensate for reactive power by using the vehicle's battery [21] [22]

Furthermore, a complex infrastructure, limited access to the electrical grid, and a consistent connector/charging level are necessary [23] The V2G technology requires extensive grid and vehicle connection Furthermore, because batteries must

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be charged and drained often during V2G operation, their lifespan is shortened Table 2.2 summarizes the various types of charging stations, including BSS, WPT, and CC stations

Table 2.2 Summary of reviews on charging methods

− Pantograph Charging: This technique of charging is a charging option This sort

of charging infrastructure is used in applications with larger battery capacity and power requirements, such as buses and trucks While the cost of charging infrastructure rises, this charging technique requires less investment in the bus battery, cutting the overall cost of the bus [25] The following two types further divide pantograph charging:

− Top-down Pantograph: The charging system is referred to as an off-board top-down pantograph since it is positioned on the bus stop's roof The high

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power direct current provided by this technology has previously been tested

in Singapore, Germany, and the United States [26]

− Bottom-up Pantograph: Applications where the charging equipment is already built into the bus are ideal for this sort of charging technology Another name for this is an on-board or bottom-up pantograph [26]

Because buses in Vietnam routinely drive more than 100 kilometers per day, charge anxiety is a more serious issue than range anxiety Because it frequently enables more kW transfer and reduces the burden on the car, the off-board charger is a preferable solution for reducing charge anxiety The phrase "off-board charger" refers to a charger that provides DC power to the EV battery pack while being positioned outside of the vehicle The off-board EV charging system [27] depicted

in Figure 2.10 (Table 2.2) employs both IEC mode 4 and SAE levels 1 and 2

Figure 2.10 EV charging configuration for off-board

On the other hand, on-board charging, adds weight to the vehicle and delivers a lower kW transfer The weight, size, and cost constraints of single-phase on-board chargers limit the transfer of high power [27] [28] As a result, charging takes longer than with the off-board charging configuration Figure 2.11 [29] [30] depicts

an EV charging solution with an on-board charger for AC (Modes 1 and 2 and Level 1 and 2 per IEC and SAE standards, respectively) The DC charging levels are listed in Table 2.2

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Figure 2.11 EV charging configuration for on-board

A variety of EV charging standards are utilized internationally to deal with EV charging infrastructure For example, whereas Japan and Europe use the CHAdeMO charging standard, the United States uses the IEEE and SAE standards The Standards Administration of China (SAC) uses GB/T standards, which are similar

to IEC standards In SAE, the phrase "Level" is used to define the power level, but

in IEC, the word "Mode" is used Table 2.3 summarizes the ICE and SAE charging standards

In most homes or companies, Level 1/Mode 1 is used for overnight slow charging Level 2/Mode 2 and Level 3/Mode 3 charging modes are utilized by both public and private charging stations, but mode 4 in IEC and SAE is intended for fast charging [11]

Table 2.3 IEC and SAE standards: Current and voltage level for AC and DC

charging

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Chapter 3: DESIGN AND CALCULATION OF ELECTRIC BUS

This chapter describes a process for designing the size of energy storage and power components in an electric bus prototype To satisfy the performance of motors, the battery for energy storage system (lithium-ironphosphate battery type) is built with

a number of series and parallel circuits The traction motor size is also explained in terms of how to design it in order to accomplish the stated acceleration and requirements On the theoretical foundations discussed in Chapter 2, the essential components will be explained and detailed how to compute for the specification of

an electric bus

Figure 3.1 The parameter of Vinbus

Because numerous bus lines are due to start operating in Ho Chi Minh City, they must also be changed, and the length of the bus lines must be suitably reduced As a result, a short-distance electric bus power system must be designed We determined the pure electric vehicle power system with an battery pack as the power and a motor as the driving device after referring to the design of similar vehicles on the market and the actual needs of Ho Chi Minh City's public transportation system

of dynamic design Table 3.1 and 3.2 [31] [32]displays all of the vehicle parameters

Table 3.1 Vehicle Parameters of pure Electric Bus

of dynamic design Table 3.3 [31] [33] [34] displays all of the vehicle parameters

Table 3.3 Coefficients of Vinbus Electric Vehicle

Vehicle’s Coefficients

3.2.2 Chossing Auxiliaries Component

Aside from the engine system, this electric bus contains subsystems and auxiliary electrical components such as an air conditioner, a steering hydraulic pump, and a coolant system, among others Their worth can be summarized as follows

Types of electrical loads on cars are connected in parallel and can be divided into 3 types:

− Continuous working load

− Working load is not continuous

− The load works for a short period of time

Here are some component we divide they are three kind of auxiliaries component and the value of power as show on these table below [2] [33] [35]:

Table 3.4 Power dissipation of the connecting loads continue on the car

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Indicator light 30 Vehicle cooling system 500

Steering System 3.000

Table 3.5 Power dissipation of cockroach loads section on the car

Table 3.6 Working load in a short time

3.3.1 Motor Parameter Calculation

According to [36] [37], the automobile dynamic performance index, choosing the best driving motor has an influence on its dynamic performance The power system must meet maximum speed, acceleration, maximum climbing slope, and rated torque The dynamic performance of pure electric vehicles must meet the driving force Ft delivered to the wheels by the motor while also overcoming vehicle resistance while driving The rolling resistance Ff caused by the road surface when driving, the air resistance caused by air friction The driving equation as follows:

It is possible to obtain by substituting the calculation formula for each force into formula that: