DESIGN OF A HYBRID ELECTRIC VEHICLE

TOSHALI MOHANTY (109EE0286)

Department of Electrical Engineering

National Institute of Technology Rourkela

DESIGN OF A HYBRID ELECTRIC VEHICLE

A Thesis submitted in partial fulfillment of the requirements for the degree of

Bachelor of Technology in Electrical Engineering
By
TOSHALI MOHANTY

Under guidance of
Prof. BIDYADHAR SUBUDHI

Department of Electrical Engineering

National Institute of Technology
Rourkela-769008 (ODISHA)
May-2013

-2-

DEPARTMENT OF ELECTRICAL ENGINEERING

NATIONAL INSTITUTE OF TECHNOLOGY, ROURKELA
ODISHA, INDIA-769008

CERTIFICATE
This is to certify that the thesis entitled Design of a Hybrid Electric Vehicle, submitted by
Toshali Mohanty (Roll. No. 109EE0286) in partial fulfilment of the requirements for the award
of Bachelor of Technology in Electrical Engineering during session 2012-2013 at National
Institute of Technology, Rourkela. A bonafide record of research work carried out by them under
my supervision and guidance.
The candidates have fulfilled all the prescribed requirements.
The Thesis which is based on candidates own work, have not submitted elsewhere for a
degree/diploma.
In my opinion, the thesis is of standard required for the award of a bachelor of technology degree
in Electrical Engineering.
Place: Rourkela

Dept. of Electrical Engineering

National institute of Technology
Rourkela-769008

Bidyadhar Subudhi
Professor

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ACKNOWLEDGEMENTS

I wish to express my sincere gratitude to PROF. S. K. SARANGI, Director and Prof. A. K.

PANDA, H.O.D of Electrical Engineering Department of National Institute of Technology,
Rourkela for providing me an opportunity to do my project work on DESIGN OF A HYBRID
ELECTRIC VEHICLE. This project bears on imprint of many peoples. I sincerely thank to my
project guide Prof. Bidyadhar Subudhi, Department of Electrical Engineering, National Institute
of Technology, Rourkela for his able guidance and constant encouragement in carrying out this
project work. Last but not least I wish to avail myself of this opportunity, express a sense of
gratitude and love to my friends for their manual support, strength, help and for everything.

Dedicated to
My parents

ABSTRACT

A 'gasoline-electric hybrid car' or 'hybrid electric vehicle' is a vehicle which relies not only
on batteries but also on an internal combustion engine which drives a generator to provide the
electricity and may also drive a wheel. It has great advantages over the previously used gasoline
engine that drives the power from gasoline only. It also is a major source of air pollution. The
objective is to design and fabricate a two wheeler hybrid electric vehicle powered by both battery
and gasoline. The combination of both the power makes the vehicle dynamic in nature. It
provides its owner with advantages in fuel economy and environmental impact over conventional
automobiles. Hybrid electric vehicles combine an electric motor, battery and power system with
an internal combustion engine to achieve better fuel economy and reduce toxic emissions. In
HEV, the battery alone provides power for low-speed driving conditions where internal
combustion engines are least efficient. In accelerating, long highways, or hill climbing the
electric motor provides additional power to assist the engine. This allows a smaller, more
efficient engine to be used. Besides it also utilizes the concept of regenerative braking for
optimized utilization of energy. Energy dissipated during braking in HEV is used in charging
battery. Thus the vehicle is best suited for the growing urban areas with high traffic.
Initially the designing of the vehicle in CAD, simulations of inverter and other models are done.
Equipment and their cost analysis are done. It deals with the fabrication of the vehicle. This
includes assembly of IC Engine and its components. The next phase consists of implementing
the electric power drive and designing the controllers. The final stage would consist of increasing
the efficiency of the vehicle in economic ways.

CONTENTS
Abstract

Contents

ii

List of Figures

iv

List of Tables

vi

Abbreviations and Acronyms

vi

CHAPTER 1
INTRODUCTION
1.1 Motivation
1.2 Concept of HEV
1.3 Basic design of HEV
1.4 Advantages of HEV
1.5 Claims for the project

1
1
2
2

1.6 Overview Of Proposed Work done

1.7 Thesis Objectives
1.8 Organization of Thesis

3
3
4

CHAPTER 2
HYBRID ELECTRIC VEHICLE
2.1 Introduction

2.2 CAD Model of HEV

2.2.1 Components

11

2.2.2 Description of the diagrams

11

2.3 Block diagram of HEV

13

2.4 Working of HEV

13

ii

CHAPTER-3
ELECTRIC BASED FRONT WHEEL DRIVE AND ITS
COMPONENTS
3.1 Introduction

16

3.2 MATLAB Circuit diagram

16

3.3 Components of electric vehicle

17

3.3.1 Battery

17

3.3.2 Three phase inverter

20

3.2.2.1 Advantages of PWM VSI

21

3.3.3 BLDC Motor

21

CHAPTER-4
GASOLINE BASED REAR WHEEL DRIVE AND ITS
COMPONENTS
4.1 Gasoline Engine

23

4.2 Carburetion

23

4.3 CAD Model of IC Engine

24

CHAPTER-5
EFFICIENCY OF POWER DRIVES
5.1 Introduction

26

5.2 Indicated Thermal Efficiency

26

iii

5.3 Brake Thermal Efficiency

26

5.4 Mechanical Efficiency

26

5.5 Specific Fuel Cosumption

26

5.6 Efficiency of electric drive

27

CHAPTER-6
EXPERIMENTAL RESULT

6.1 Analysis

29

CHAPTER-7
CONCLUSION
7.1 Conclusion

35

7.2 Contribution of the project

35

7.3 Future work

35

References

37

Appendix
a) Equipments used to design the vehicle

39

LIST OF FIGURES
Fig. No

Name of the Figure

Page. No.

1.1

Schematics of HEV

2.1

Rendered View

2.2

Rear Rendered View

2.3

Side Rendered View

2.4

Front Rendered View

2.5

Transparent Body Frame Isometric view

iv

2.6

Transparent Body Frame Isometric view

10

2.7

Wire Frame Model Side View

10

2.8

Block diagram of HEV

12

2.9

Throttle position sensor

13

3.1

MATLAB Circuit diagram of electric vehicle

16

3.2

Closed loop PWM VSI model

20

3.3

Output of PWM VSI without filter

20

3.4

Output of PWM VSI with filter

20

3.5

Diagram of BLDC Motor

21

4.1

CAD Model of IC Engine

24

6.1

Temperature Distribution of Cylinder Head

29

6.2

Heat Flux Distribution in a Cylinder

29

6.3

Stress analysis of chassis

30

6.4

Output of inverter circuit

30

6.5

Armature current of electric drive circuit

31

6.6

Speed of BLDC motor at no load

31

6.7

Output torque of BLDC motor at no load

31

6.8

Side view of real time model of HEV

32

6.9

Front view of real time model of HEV

32

6.10

Battery based drive circuit for HEV

33

LIST OF TABLES

Table. No.
2.1

Name of the Table

Throttle position sensor

Page. No.
13

3.1

Average Cell Voltage during Discharge in Rechargeable Batteries

18

3.2

Battery Characteristics Affecting Thermal Design

18

3.3

Specific Energy and Energy Density of Various Batteries

19

3.4

Life and Cost Comparison of Various Batteries

ABBREVIATIONS AND ACRONYMS

HEV

Hybrid Electric Vehicle

AC

Alternating Current

DC

Direct Current

BLDC

Brushless DC

IC

Internal Combustion

CVT

Continuously Variable Transmission

CAD

Computer-aided Design

PWM

Pulse Width Modulation

VSI

Voltage Source Inverter

MATLAB

Matrix Laboratory

vi

19

CHAPTER

Introduction
1

1.1

MOTIVATION:

Around 93% of todays automobiles run on petroleum based product, which are estimated to be
depleted by 2050 [1]. Moreover, current automobiles utilize only 25% of the energy released
from petroleum and rest is wasted into the atmosphere [2]. Despite recent efforts to improve fuel
efficiency and reduce toxic emissions in cars, emissions have continued to increase steadily in
the past two decades.
For preservation of gasoline for future and increasing the efficiency of vehicle an electric vehicle
can be a major breakthrough. An electric vehicle is pollution free and is efficient at low speed
conditions mainly in high traffic areas. But battery charging is time consuming. Moreover, it
cannot provide high power required by drives during high speed conditions or in slopes of hilly
areas. Gasoline engine proves its efficiency at higher speeds in high ways and waste a lot of
energy in urban areas. A hybrid vehicle solves these problems by combining the advantages of
both the systems and uses both the power sources at their efficient conditions. The objective of
this project aims at better utilization of fuel energy and reduces dependence on non-renewable
resources using latest technology. The implementation involves development of HEV that uses
battery as well as gasoline power for propulsion of vehicle.

1.2

CONCEPT OF HEV:

A 'gasoline-electric hybrid vehicle' is an automobile which relies not only on gasoline but also
on electric power source. In HEV, the battery alone provides power for low-speed driving
conditions. During long highways or hill climbing, the gasoline engine drives the vehicle solely.
Hybrid electric vehicles comprise of an electric motor, inverter, battery as electric drive and an
internal combustion engine with transmission connected as gasoline based drive. It is to achieve
better fuel economy and reduce toxic emissions.

It has great advantages over the previously used gasoline engine that is driven solely from
gasoline. This hybrid combination makes the vehicle dynamic in nature and provides its owner a
better fuel economy and lesser environmental impact over conventional automobiles.

1.3

BASIC DESIGN OF HEV:

The basic design consists of a dc power source battery. The battery is connected to inverter that
is fed to a BLDC motor that works on AC. The motor is attached to the front wheel of the two
wheeler vehicle. As the motor rotates the attached wheel rotates too, thus, leading to vehicle
motion. At low speeds this mode of propulsion is used. The next phase consists of an IC engine
that moves the piston continuously. This is connected to the transmission and thus, the vehicle
moves.

BATTERY

CONVERTER

RESERVOIR

ELECTRIC MOTOR

ENGINE

1.1 Schematics of HEV

1.4

ADVANTAGES OF HEV:

HEVs have been vehicles of numerous advantages. Hybrids do indeed get superior gas mileage.
They use less gasoline, and therefore emit less greenhouse gas. Thus the problem of
environmental pollution can be avoided to certain extent. Apart from that they use less gasoline
2

in comparison to the other vehicles of same power that run only on gasoline. Thus this reduces
the extreme dependence on gasoline which is a non-renewable source of energy. This encourages
the method of sustainable development that has been the topic of concern in the modern society.
Moreover, HEVs mode of operation are maximum efficient to the conditions, i.e, at low speed
and high traffic areas where gasoline engine is least efficient with a lot of energy wasted, HEV
moves with power from battery. At up slopes where high power is required and battery is
inefficient,

gasoline

power

is

used

for

vehicle

motion.

Thus the advantages of HEV make it superior than any other vehicle of today.

1.5

OVERVIEW OF PROPOSED WORK DONE

Many a literature are used to carry out the project which includes notes on HEVs, electric drives,
energy management, batteries, internal combustion engine, etc. Reference [1]-[2] gives us the
data of the global scenario regarding the vehicle dependence on non-renewable resource gasoline
and the expected year of depletion of the product. It gave a detailed discussion on importance of
development of other types of vehicles such that too much dependence on gasoline based can be
reduced. Reference [3]-[4] gives an overview about the electric drive technology. Reference [5]
describes about battery technology available in the market. Reference [5] tells about the various
batteries and their advantages. Reference [6] gives theories about motors, their efficiency as per
the application and about the controller. References [7]-[8] describe the internal combustion
engine, ways to increase their efficiency etc. Reference [9]-[11] gives an overview of HEV and
its associated advantages.
1.6

THESIS OBJECTIVES:

The following objectives are to be achieved at the end of the project.

a) Design and virtual analysis of the vehicle.
b) Designing & Assembling of IC Engine.
c) Designing & Assembling of the Electric Power Drive.

d) Designing a two wheeler vehicle with front wheel powered by electric motor and rear
wheel drive powered by an Internal Combustion Engine.
e) A switching circuit used to switch from IC Engine to the electric power and vice
versa.
f) Implementation of control algorithm by microcontroller
g) Efficiency calculation of vehicle.

1.7

ORGANISATION OF THESIS:

The thesis is organised into seven chapters including the chapter of introduction. Each
chapter is different from the other and is described along with the necessary theory required to
comprehend it.
Chapter2 focuses on describing the basic concept of Hybrid Electric Vehicle. The basic
schematic of Hybrid Electric Vehicle is shown in the section. Through an advanced CAD Model
of two-wheeler proposed Hybrid Electric Vehicle the exact design model of the vehicle is
illustrated. The advantages of HEV is described and analysed. The next section of the chapter
explains the working of HEV through a neat block diagram.
Chapter3 describes electric drive and its components. In the initial section of the chapter
an introduction to electric vehicle is described. Next the MATLAB Simulink model is shown
with proper demonstration to the circuit. The next section gives overview of various components
of electric drive. The battery and its various types are described. With a proper comparison
between the types and associated discussions the best suited battery for HEV application is
chosen. Then PWM inverter used in the vehicle is described and analysed. The last section of the
chapter contains the discussions on the BLDC motor used and its advantages.
Chapter4 describes the gasoline based engine. In the section the theories related to
gasoline engine, carburetion etc. are discussed. The CAD model of IC engine is illustrated.
Chapter5 describes methods for efficiency calculation of vehicle. Various efficiencies
are judged and calculated for proper modelling of a vehicle. The efficiencies include indicated
4

Thermal Efficiency, brake thermal efficiency, mechanical efficiency, specific fuel consumption,
electric drive efficiency etc.
Chapter6 presents the analysis of various components of the vehicle. The analysis
includes the thermal analysis of the engine. It is done to avoid damages to the engine. The
analysis plot shows the portions of engine prone to high, medium or low temperature. According
to the analysis the designing of the engine is done. The next discussion is on the stress analysis
of the chassis. Through the analysis the chassis designing can be done with proper stress
distribution. The next section contains the MATLAB simulation of the three phase PWM VSI. It
also includes the simulation of electric drive with plot between torque-time, armature currenttime, voltage-time and speed-time.
Chapter7 concludes the work performed so far. The possible limitations in proceeding
research towards this work are discussed. The future work that can be done in improving the
current scenario is mentioned. The future potential along the lines of this work is also discussed.

CHAPTER

Hybrid Electric Vehicle

6

2.1

INTRODUCTION

The project discloses a hybrid system consisting of an Electric and Internal Combustion(IC)
based power drives. The front wheel is being propelled by battery and the rear wheel is
powered by gasoline, i.e, it includes a single cylinder, air cooled internal combustion engine
and a BLDC motor based electric power drive used for hybrid powering of the vehicle. The
controller is designed to implement the switching between IC Engine and Electric motor
depending on the power requirement and load conditions.

2.2

CAD MODEL OF HEV

2.1 Rendered View

2.2 Rear Rendered View

2.3 Side Rendered View

8

2.4 Front Rendered View

2.5 Transparent Body Frame Isometric view

9

2.6 Transparent Body Frame Isometric view

6
7
10
12

9
3

11

5
8

13

2
14

16
15

2.7 Wire Frame Model Side View

10

2.2.1 Components:
1) Tyre 2) Hub Motor 3) Suspension 4) Headlamp 5) Body Cover 6) Display
7) Microcontroller 8) Hub Motor Controller 9) Seat 10) Engine 11) Front Battery
12) Fuel Tank 13) Chassis 14) Rear Tyre 15) Transmission 16) Rear Battery

2.2.2 Description of the diagrams:

Fig. 1 is the rendered design of the hybrid vehicle modelled in CAD software.
Fig 2, fig 3, fig 4 are rear, side and front view of the vehicle respectively.
Fig 5, figs 6 consist of transparent body frames to show the interior components of the design.
Fig 7, fig 8, fig 9 are the drafted view of side, top and isometric views of the vehicle
respectively.
The vehicle at lower speed act as front wheel drive and at high speed gets switched to rear
wheel drive automatically. Component 1 in Fig 7 shows the attachment of tyre with the hub
motor (2 of Fig 8). There is no need for any gear reduction since the torque produced is
sufficient enough to drive the vehicle. The axel of the motor is connected to the suspension (3
of Fig 8). Suspension is connected to the handle which is connected to the main chassis.
Accessories such as headlamp (4 of Fig 8), display (6 of Fig 8) are included as user aid. A
microcontroller (7 of Fig 8) powered up from battery, performs the switching from electric to
internal combustion or vice versa as per the requirement. It senses throttle position and
controls the hub motor speed via controller circuit and the IC Engine via servo motor to
control speed of rear wheel. Due to space constraints, two batteries (16 of Fig 8) are placed in
front and two are placed near the fuel tank. Engine (10 of Fig 8) is connected to the main
chassis and seat (9 of Fig 8) is situated above the engine. CVT is connected to the crank shaft
of the engine to avoid any shocks while switching and it makes the controlling simpler and
easier.

11

2.3

BLOCK DIAGRAM OF HEV

2.8 Block diagram of HEV

2.4

WORKING OF HEV

In HEV, the battery alone provides power for low-speed driving conditions where internal
combustion engines are least efficient. In accelerating, passing, or hill climbing where high
power is required battery provides power to electric motor as an additional power to assist the
engine. This allows a smaller, more efficient engine to be used.
A throttle position sensor (TPS) is a sensor used to monitor the position of the throttle in
an internal combustion engine. It consists of a hall sensor. When the accelerator throttle angle

12

changes magnetic field is created and it creates voltage across position sensor terminal. Thus
for various angles, various voltages are obtained.

2.9 Throttle position sensor

TABLE 2.1: Throttle position sensor
Throttle Position Sensor
Rotational Angle
0

Signal Voltage
0.000

Under Travel
10
13

0.450
Closed Throttle

0.901

20

1.440

30

1.900

40

2.370

50

2.840

60

3.310

70

3.780

80

4.240

13

84

Full Throttle

90

4.538
4.538

Over Travel
100

5.00

Values were calculated for VREF = 5.0 volts.

HEV consists of a throttle position sensor, i.e, hall sensor. It gives voltage as output with
respect to the angle displacement in the accelerator. The analog voltage generated is
converted to digital through ADC and is given to microcontroller. If the speed corresponding
to the angle deviation in accelerator is less than 30km/hr then the relay is switched on. The
relay switching completes the circuit of the battery, inverter and hub motor; and vehicle is
motioned by electric power. If the speed directed by accelerator is greater than 30km/hr, then
the engine is started by closing the circuit of starting motor through a relay. The starting
motor circuit is activated for five hundred milliseconds such that the vehicle is started. Once
the vehicle starts the valve of engine for gasoline intake opens by servo motor. The amount of
opening is controlled by the PWM generated by the microcontroller as directed by the
accelerator.

14

CHAPTER

Electric Based Front Wheel

Drive and Its Components
15

3.1

INTRODUCTION

Electric Vehicle consists of battery, inverter and BLDC motor. It is a part of hybrid electric
vehicle that is propelled during low speed condition. It is pollution free as there is no
combustion of fuel involved. It is a soundless vehicle. It is a very efficient vehicle as there is
no loss of energy involved.

3.2

MATLAB CIRCUIT DIAGRAM

3.1 MATLAB Circuit diagram of electric vehicle

The electric vehicle circuit consists of a battery. The battery is connected to a PWM VSI to
convert DC voltage to AC. This AC is fed to the BLDC motor. BLDC motor has several
16

advantages in comparison to other motors. It has wide speed variations as DC motor but do
not have the drooping characteristics as is there in DC motor. The output is continuously
sensed by voltage sensor. It is given to the voltage regulator. The function of voltage
regulator is to convert three phase RYB voltage to dq axis. It is then compared and the error is
fed to PID controller. Thus the required voltage is obtained and is fed to PWM generator as
reference. PWM generator generates pulses to be fed to the IGBT/Diode switches. Thus a
regulated output voltage is obtained from the closed loop VSI and is given to BLDC motor
for best output.
3.3

COMPONENTS OF ELECTRIC DRIVE

3.3.1

BATTERY

Hybrid Electric Vehicle uses battery as one of its power source for vehicle motion during at
low power conditions. Batteries are devices that consist of electrochemical cells and provide
electrical energy converted from stored chemical energy [5]. Generally batteries are of two
types: primary batteries that are disposable and secondary batteries that are rechargeable.
Secondary batteries are preferred for vehicles as they can be rechargeable.
There are six major rechargeable batteries available today. They are as follows: lead-acid (Pbacid), nickel-cadmium (NiCd), nickel-metal hydride (NiMH), lithium-ion (Li-ion), lithiumpolymer (Li-poly), zinc-air [5]. The basic performance characteristics of the battery which
influence the design are as follows:
Charge/discharge ratio (c/d ratio):
The charge/discharge ratio is defined as the Ah input over the Ah output with no net
change in the state of charge. Less the c/d ratio better is the battery.
Round trip energy efficiency:
The energy efficiency over a round trip of full charge and discharge cycle is defined
as the ratio of the energy output over the energy input at the electrical terminals of the
battery. More the round trip energy efficiency better is the battery.
Charge efficiency:
The charge efficiency is defined as the ratio of the Ah being deposited internally
between the plates over that delivered to the external terminals during the charging
process. More the charge efficiency better is the battery.

17

 Internal impedance:
Batteries have internal resistances. For the internal resistances present, the battery
cannot operate in the full efficient condition. The power delivered at load decreases
and hence less is the internal resistance of battery better is its performance.
Temperature rise:
Temperature rise is an important factor for batteries as beyond a certain temperature
value the battery may lose its charge capacity. Thus, more the temperature sustaining
value of the battery better is its efficiency and lifetime.
Life in number of c/d cycles:
Batteries have a particular life in number of c/d cycles. More the value better is the
battery.
TABLE 3.1: Average Cell Voltage during Discharge in Various Rechargeable Batteries
Electrochemistry Cell
Voltage
Lead-acid

2.0

Nickel-cadmium

1.2

Nickel-metal hydride

1.2

Lithium-ion

3.4

Lithium-polymer

3.0

Zinc-air

1.2

TABLE 3.2: Battery Characteristics Affecting Thermal Design

Battery
Operating
Overcharge Heat
Mass
temperature Tolerance
capacity
density
range C
Wh/kg-K
kg/liter
Lead-acid
(Pb-acid)
Nickelcadmium
(NiCd)

10 to 50

High

0.35

2.1

Entropic
heating on
discharge
W/A-cell
0.06

20 to 50

Medium

0.35

1.7

0.12

10 to 50

Low

0.35

2.3

0.07

10 to 45

Very Low

0.38

1.35

50 to 70

Very low

0.40

1.3

Nickel-metal
hydride
Lithium-ion
Lithiumpolymer

18

TABLE 3.3: Specific Energy and Energy Density of Various Batteries

Battery
Specific
Energy
Specific
Power
Energy
Density
Power
Density
Wh/kg
Wh/liter
W/kg
W/liter
Lead-acid
3040
7075
~200
~400
(Pb-acid)
Nickel4060
70100
150200
220350
cadmium
(NiCd)
5065
140200
~150
450500
Nickel-metal
hydride
90120
200250
200220
400500
Lithium-ion
Lithium100200
150300
>200
>350
polymer
Zinc-air
140180
200220
~150
~200
TABLE 3.4: Life and Cost Comparison of Various Batteries
Battery
Cycle life in Calendar
Self
full
life in years discharge
discharge
rate
cycles
%/month at
25 C
Lead-acid
500-1000
5-8
3-5
(Pb-acid)
Nickel1000-2000
10-15
20-30
cadmium
(NiCd)
1000-2000
8-10
20-30
Nickel-metal
hydride
500-1000
----5-10
Lithium-ion
Lithium500-1000
----1-2
polymer
Zinc-air
200-300
----4-6

Relative
cost
$/kWh

200-500
1500

2500

3000
>3000
------

The performance characteristics and properties of various electrochemistries presented in the

preceding sections are summarized and compared . It is noted that despite of little advantages
in all the factors, the overall cost of the lead-acid battery is low compared to NiCd, NiMH and
Li-ion batteries. Because of its least cost per Wh delivered over the life, the lead-acid battery
is best suited for vehicle application where low cost for customers are necessary.
19

3.3.2

THREE PHASE INVERTER

In a three phase voltage source inverter bridge, controlled switching with the help of IGBT is
used to control voltage in normal operation, and a parallel diode is connected to make the
inverter bidirectional in nature. AC voltage is obtained by switching the IGBT switches in a
specific pattern to obtain bipolar square two level waveform.
The bipolar square wave results in high harmonic content in the output. Use of filter makes
the model costly and prohibits it from becoming bidirectional as concluded from simulation
outputs.

3.2 Closed loop PWM VSI model

3.3 Output of PWM VSI without filter

3.4 Output of PWM VSI with filter

20

In the three phase PWM VSI, high dv/dt switching leads to introduction in harmonics to the
circuit. But its low cost and small size makes it suitable to be used for two-wheeler hybrid
electric vehicle.
3.3.2.1 ADVANTAGES OF PWM VSI

It gives constant voltage ouput.

It gives square wave output which almost resembles trapezoidal wave required by
BLDC motor.

Smaller in size

Less cost

3.3.3

BLDC MOTOR

BLDC motor is a closed loop synchronous motor. It has all the characteristics of DC Motor
with some added features. It advantages are as follows:

It is cheap.

It can save 30% to 50% of power consumed by a normal motor and has high
efficiency of 80% to 90%.

It is small in size. It can have high torque at low speed.

Speed range can be customized

Replace the AC + frequency equipment minimizing harmonics introduction to

the circuit.

3.5 Diagram of BLDC Motor

21

CHAPTER

Gasoline Based Rear Wheel

Drive and Its Components
22

4.1

GASOLINE ENGINE

An engine is a device that transforms one form of energy to another and if an engine converts
thermal energy to mechanical works, it is called as heat engines. A heat engine converts the
stored chemical energy of the fuels to thermal energy and finally this thermal energy is
converted to mechanical work. Different types of engines are available such as: Internal
Combustion, External Combustion, Reciprocating, Rotary etc. [7]. Internal Combustion
engine delivers higher thermal efficiency and moreover weight of these engines is quiet low
as compared to the powered delivered by them. There are some disadvantages as well, such as
the vibration generated and the limitation of fuel variety to be used. Considering all the
factors, reciprocating internal combustions are the most suitable in two wheelers.
Four stroke engines provide greater efficiency that two stroke engines and the emissions
released into the atmosphere are less. Since the compression ratio is lower for smaller
engines, spark based ignition system is preferred and gasoline is used as fuel.
A 100 cc, four stroke, single cylinder, air cooled petrol engine has been used which has
carburetted type fuel supply system and magneto based spark ignition system.

4.2

CARBURETION

Spark based ignition engines use volatile liquids as fuels, thus the preparation of fuel air
mixture is done outside the engine cylinder. The purpose of carburetion is to provide a
combustible mixture of fuel and air in the required quantity and quality for efficient operation
of engine under all conditions [8].Under normal conditions it is desirable to run the engine on
the maximum economy mixture, and for quick acceleration rich mixture is used. Due to the
downward movement of the piston, air is sucked into the cylinder, creating a lower pressure
in the gas chamber. In carburetor, air passing through a tube which contains fine orifice are
exposed to the atmosphere. The rate of fuel delivered depends on the pressure difference. A
throttle valve controls the volume of the air that needs to be drawn.
Air cooled system: In this, a current of air is made to flow past the outside of the cylinder
barrel, outside surface area of which has been considerably increased by providing cooling
fins. The heat transfer rate is quiet low between metal and air, thus suitable for light weight
engines. Cooling fins are cast integral with the cylinder and cylinder head to obtain maximum
heat transfer. The heat dissipating capacity depends on both cross-section and length.

23

Magneto based ignition system: Magneto is a special type of ignition system with its own
electric generator to provide the necessary energy for the system. A magneto when rotated by
the engine is capable of producing a very high voltage and does not need a battery as a power
source. Maintenance problems are less in magneto based system as there is no battery.

4.3

CAD MODEL OF IC ENGINE

4.1 CAD Model of IC engine

A single cylinder, gasoline based air cooled engine is designed in computer aided software,
comprising of part modelling with part assembly. An engine consist of various parts such as
piston, cylinder head, cam shaft, chains, timing controlling, fuel supply system, spark ignition
system.
24

CHAPTER

Efficiency of Power Drive

25

5.1

INTRODUCTION

Efficiency is indicated as the ratio of output work to the input energy. Engine efficiency is
calculated by various performance parameters, such as Indicated Thermal Efficiency, Brake
Thermal Efficiency, Mechanical Efficiency, Volumetric Efficiency, Relative Efficiency etc.

5.2

INDICATED THERMAL EFFICIENCY

It is the ratio of energy in the indicated power ip, to the input fuel energy in appropriate units.
Efficiency = ip[kJ/s]/energy in fuel per sec [kJ/s]
= ip[kJ/s]/(mass of fuel/s x calorific value of fuel)

5.3

BRAKE THERMAL EFFICIENCY

Brake thermal efficiency is the ratio of energy in the brake power, bp, to the input energy in
appropriate units.
Efficiency = bp/( mass of fuel/s x calorific value of fuel)

5.4

MECHANICAL EFFICIENCY

Mechanical efficiency is defined as the ratio of brake power (delivered power) to the
indicated power (power provided to the piston).
Fp = ip-bp

5.5

SPECIFIC FUEL CONSUMPTION

The fuel consumption characteristic of an engine are generally expressed in terms of specific
fuel consumption in kilograms of fuel per kilowatt-hour. It reflects how good is the engine
running or performing. It is inversely proportional to the thermal efficiency of engine.
Sfc = Fuel consumption per unit time/ Power
26

5.6

EFFICIENCY OF ELECTRIC DRIVE

Efficiency = ( Output power/Input power)

= (T*w/Vdc Idc )

Thus through the expressions efficiency of the vehicle is calculated. The efficiency of IC
engine at low speed is very less,i.e, it is less than even 25%. Whereas at this speed the
efficiency of battery based drive is almost hundred percent. At high speeds both of them have
the same efficiency as both of them are propelled by gasoline energy. Thus from the above
discussions it can be concluded that hybrid electric vehicle is more efficient than normal
vehicle based on gasoline power source.

27

CHAPTER

Experimental Results
28

6.1

ANALYSIS

During combustion of gasoline, high temperature gases are generated which increase the
temperature of the cylinder head. A long, conductive radiating fins are casted with the
cylinder head to remove the heat from the interior to the environment. High temperature
affects the performance of the engine, combustion of the lubricating oil is a serious problem
which needs to be taken care of. Fig. 6.1 shows the temperature distribution of the cylinder
head when the vehicle is running at higher speeds and heat transfer is mainly through
convection. The simulation is colour coded which depicts that red colour shows higher
temperature and blue colour shows the region of lower temperature. Fig. 6.2 shows the heat
flux distribution in a cylinder head. Fig 6.3 shows the stress analysis of the the chassis. The
bluish portions experience less stress and the reddish portions have more stress. The chassis
portion with red in colour is to be made with proper care. Fig 6.4 shows the inverter output of
the electric vehicle. The square wave produced is fed to the BLDC motor for maximum
efficiency. Fig 6.5 shows the variation of torque, speed, output voltage and armature current
with time of the electric drive.

6.1 Temperature Distribution of Cylinder Head

6.2 Heat Flux Distribution in a Cylinder

29

6.3 Stress analysis of chassis

6.4 Output of inverter circuit

30

6.5 Armature current of electric drive circuit

6.6 Speed of BLDC motor at no load

6.7 Output torque of BLDC motor at no load

31

6.8 Side view of real time model of two-wheeler HEV

6.9 Front view of real time model of two-wheeler HEV

32

6.10 Battery based drive circuit for HEV

33

CHAPTER

Conclusion
34

7.1

CONCLUSION

HEV is a vehicle that uses two sources of power- gasoline and battery. For low power
application battery drive is used whereas for high power application where power
requirement is very high gasoline engine is used. Gasoline drive is most efficient at high
speed drive. Thus HEVs both mode of operation occurs at their maximum efficiency. But in
gasoline engine low speed operation is not efficient. Its high speed mode is only efficient.
Therefore, it gives twice the mileage given by a normal vehicle. As this hybrid vehicle emits
50% less emission than normal vehicle it plays an important role for reducing pollution to
certain extent without compromising with efficiency. Thus it is most efficient in urban areas
mainly in high traffic where gasoline engines are least efficient as the energy from gasoline is
being wasted away and creates pollution.
7.2

CONTRIBUTON OF THE PROJECT

The current society mostly depends on petroleum as the major source power for vehicle
propulsion. The electric vehicle is not very efficient for all power conditions, i.e, it cannot
provide power for high speed conditions. Through the project a hybrid method of both the
vehicles is proposed which utilises the efficiency of both the vehicles. This method is
implemented in two-wheeled vehicles that are mostly preferred by public. Thus proper
manufacturing and cost analysis can make the vehicle a major breakthrough.
7.3

FUTURE WORK

The future work deals with finding ways to charge battery automatically without using
electricity. The idea is to use that energy which is lost in the exhaust and cooling of the
engines. According to Sankey Diagram for gasoline engines only 25% of fuel energy is
converted to useful work and rest is rejected into the atmosphere. Nearly 40% energy is
wasted in exhaust and 30% as coolant. To convert this unused energy a stirling engine and an
array of thermocouple can be used which converts heat into mechanical energy.
To implement the stirling engine concept an exhaust pipe can be connected to one of the hot
cylinders of stirling engine, the cold cylinder is exposed to the atmosphere. The heat
difference created drives the stirling engine. The stirling engine is connected to dynamo. As
the stirling engine rotates through dynamo electric power is produced used to charge the
battery.
35

Thermocouple based electric generation can be done by connecting thermocouples in a

parallel array. They are thermally coupled to the cylinder head. The electric output is
connected the electric storage recharging circuit. Mechanical energy will be converted to
electrical energy by generator and this will be used to recharge the batteries. This concept has
never been used in any vehicle worldwide or in India. Theoretically we can achieve twice the
mileage with the same fuel consumption and reduce the carbon emission to 50%.

36

REFERENCES
[1] Resources magazine publication.Replacing Oil: Alternative Fuels and Technologies
http://www.rff.org/Publications/Resources/Pages/Replacing-Oil.aspx
[2] Oil depletion analysis centre. ODAC Newsletter - 6 July 2012.http://www.odacinfo.org/newsletter/2012/07/06
[3] M. J. Riezenman, Electric vehicles, IEEE Spectrum, pp. 18101, Nov.1992.
[4] H. Shimizu, J. Harada, C. Bland, K. Kawakami, and C. Lam, Advanced concepts in
electric vehicle design, IEEE Trans. Ind. Electron., vol. 44, pp. 1418, Oct. 1997.
[5] C. D. S. Tuck, Ed., Modern Battery Technology. Harwood, p. 411, 1991.
[6] M. Terashima, T. Ashikaga, T. Mizuno, and K. Natori, Novel motors and controllers
for high-performance electric vehicle with four in-wheel motors, IEEE Trans. Ind.
Electron., vol. 44, pp. 2838, Feb. 1997.
[7] R. Prabhakar, S. J. Citron, and R. E. Goodson.Optimization of Automobile Engine
Fuel Economy and Emissions. ASME Paper 75-WAlAut-19, Dec. 1975.
[8] J. A. Cook and B. K. Powell. Discrete Simplified External Linearization and
Analytical Comparison of IC Engine Families, Proc. 1987Amer. Conrr. Con$, vol.1,
pp. 326-330, June 1987.
[9] V. Wouk, Hybrids: Then and now, IEEE Spectrum, pp. 1621, July 1995.
[10] C. Kricke and S. Hagel, A hybrid electric vehicle simulation model for component
design and energy management optimization, in Proc. FISITA World Automotive
Congress, Paris, France, Sept. 1998.
[11] M. Ehsani, K. M. Rahman, and H. A. Toliyat, Propulsion system design of electric
and hybrid vehicles, IEEE Trans. Ind. Electron., vol. 44, pp. 1927, Feb. 1997.

37

APPENDIX

38

Equipments used:
IC Engine
SI Engine
Stroke
No of Cylinders
Displacement
Cooling
Fuel Supply
Available Models

4-stroke
Single Cylinder
100c
Air Cooled
Carburetor
Kinetic Nova, Honda
Activa, Pep

Transmission
Availability

Variomatic (CVT)
Comes with engine

Power Train

Justification
4 stroke engines
have better
efficiency and this
engine commercially
cheaper than other
engines.
Its automation is
much simpler than
geared transmission.

Electric Motor
BLDC Hub Motor
Operating Voltage
Power
Max RPM
Max Current

48Volts
750 watts
380 rpm
15 amps

Voltage
Capacity

48volts
15Ah

Battery

Accessories
Tyre

Brakes

Front
Rear
Front
Rear

3.5x10
3.5x10
130 mm Drum
130 mm Drum

Front

Bottom link with

spring loaded
hydraulic damper,
80mm travel
Unit Swing with
spring loaded
hydraulic damper,
75mm travel

Suspension

Rear

Clutch

Dry automatic

Centrifugal

Microcontroller

Atmega

1250
39

Justification
High efficiency
and better load
carrying capability.

High discharge
capability

Servo Motor

PWM Controlled

15kg/cm

RPM Sensor

Hall Effect Sensor

5v operating
voltage

Stirling Engine
Electronics

Varo Board, Wires,

transistors, etc

Fabrication:
Component

Percentage Manufactured (
Company made)

Percentage Fabricated in
workshop

Engine
Transmission
Chassis
Hub motor
Stirling Engine
Suspension
Tyre
Motor Controller
Power Control System
Assembly of components
Analysis System

100%
100%
50%
100%
100%
100%
100%
0%
0%
0%
0%

50%
100%
100%
100%
100%

40

41