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Design of Environmental Friendly

Hybrid Electric Vehicle

AbstractHybrid electric vehicles (HEVs) powered by electric

machines and an internal combustion engine (ICE) are apromising mean of reducing emissions and fuel consumption

without compromising vehicle functionality and drivingperformances. This paper presents the design of an

environmental friendly hybrid car that feature the gasolineengine and batteries pack. The fuel consumption benefited byhybridization are benchmarked to conventional Gasoline and

Diesel fueled vehicles. The relationship between fuel consumptionand vehicle weight is investigated for Gasoline as well as for

Diesel fueled vehicles. Although the automobile manufacturershave reduced the greenhouse gases such as hydro-carbons,

carbon monoxide, carbon dioxide, etc., from the vehicle, theycannot produce a zero-emission vehicle unless they produce an

electric vehicle (EV). An electric vehicle is an emission free,environmental friendly vehicle. The proposed design of HEV

intelligently gets around the individual problems associated withthe gasoline engine and the electric vehicle. It diminishes theproduction of emissions and the use of fuel. The problem of

batteries for the electric vehicle is conquered. An HEV chargesitself; it never has to be plugged in. When it does not provide

power, the motor can run as a generator to transfer energy from

regenerative braking and from the gasoline engine to thebatteries.Keywords- Hybrid electric vehicles; gasoline engine; batteries;

dc motor; greenhouse gases.

I. INTRODUCTION

An electric vehicle is an emission free, environmentalfriendly vehicle. However, the electric vehicles remainunpopular among the consumers due to their lack of

performance and their inability to travel long distances without

being recharged. So, vehicle that embraces both theperformance characteristics of the conventional automobile and

the zero-emission characteristics of the electric vehicles aregreatly being anticipated by the general consumers and the

environmentalists alike.Technically, the quest for higher fuel economy is shaped bytwo major factors: how efficiently a power train converts fuel

energy into useful power, and how sleek a vehicle is in terms ofmass, streamlining, tire resistance, and auxiliary loads. On the

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other hand, vehicle functionality and comfort are shaped byvarious other factors, many of which run counter to higher fuel

economy. Examples abound, from the way torque convertersacrifices efficiency to provide better shift smoothness and

responsiveness to the wide variety of features that add mass toa vehicle.

The beauty of the HEV is that energy can be fed back intothe battery for storage, e.g., during regenerative braking (whichis otherwise wasted as heat in a conventional vehicle). Leadingcar manufacturers like Toyota and Honda have already started

mass producing HEV cars, Prius and Insight respectively,which are now becoming very popular among the consumers

for their incredible mileage and less emissions. Aside fromthat, a number of automotive manufacturers are marketing

hybrid vehicles for the general population, examples areDaimlerChrysler, Mitsubishi, Nissan, Fiat, Renault, Ford, GM,and Subaru [1]. Although the number for alternative electric

vehicles is not significantly higher when efficiency is evaluatedon the basis of conversion from crude oil to traction effort at

the wheels, it makes a difference.In [2] electrical components and overall system design of a

conversion car-turned-to-hybrid are discussed. Battery (leadacid)and super-capacitors was used as electrical storage unit.

The battery and super-capacitor used made it possible totransfer power bi-directionally between wheels, batteries, orsuper-capacitors in desired proposition. It also features EMC(Energy Management Computer) installed in the vehicle that

monitors entire system to determine what each unit should do.Using capacitor bank instead of battery alone had significantly

reduces the power and energy cycling requirement, thusincreasing battery life. However, efficiency is reduced as EMCperforms most of the power transfer between batteries andsuper-capacitors. The EMC communicates with the capacitor

and battery controllers, the IC engine, and the driver controls todecide the torque required from the battery and capacitor

motors. The parameters that are measured by the informationstructure developed are cell voltages and current, DC link

voltage, power, speed, phase current and temperatures. If themeasured parameters increased to above 10% of limit level,

system shutdown is initiated by hardware as self-protection inbattery and capacitor units.

In [3] extensive investigation is done on how batterymanagement system can be used to lengthen the lifetime of thebattery pack. The key to this approach is to monitor and charge

the batteries individually. As batteries in HEVs have verydynamic discharging and charging cycles, it needs intelligent

system to maintain and prolong the batteries life cycles. Dueto manufacturing inconsistencies and operational variations

each cell of battery can have different performancecharacteristics. The suggestion by the author is to closemonitoring and to control the charging cycles. They also

described the many possible ways to recharge the batteries assuch, constant voltage charging and constant current charging.

544In most application of HEV, a single charger is used for entire

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battery pack. The intelligent system discussed is to provideindividual chargers for each battery. This made possible due toa number of advances that have allowed DC/DC converters thatare used as the battery chargers, to be considerably reduced insize and weight. Each charger can be turned on independently

and the voltage limits can be adjusted remotely. However, there

are still needs of more research attention to improve the HEVperformance with lowest emission of carbon gasses whichseverely affect the environment.

In this paper, a new prototype of low emission environmentfriendly HEV is developed. The proposed HEV prototype is

constructed with simple design procedure and low costavailable equipments compare to mentioned design.

II. HEV CONFIGURATIONSA brief description about various HEV configurationsavailable in the market is presented. The three main

configurations are the series, parallel and the dual-modeconfigurations and the explanation of each one of them with

their merits and demerits follows.

A. Series HEV ConfigurationIn series HEV configuration, only the electric motor is

connected to the drive train and thus the vehicle is entirelydriven by the electric motor. The Internal Combustion (IC)engine drives an electric generator (commonly known as

alternator), which then supplies the electric power to the motorand battery pack. The IC engine will turn off if the battery is

fully charged. In some cases, the electric power supply for theelectric motor can come both from the battery and the enginegenerator

set. As only the electric motor is connected to thedrive train, the IC engine can run at an optimum speed to run

the generator thus greatly reducing the emissions. The batteriescan either be charged off-board, by external DC power linkfrom the electric-grid, or on-board, with the help of an

alternator and an IC engine. In this setup, it is possible todesign the operation such that the IC engine never idles andthus the overall emissions are reduced. The schematics of

series HEV is shown in Figure 1.Figure 1. Series HEV drive train

It can be seen that the IC engine is connected to thealternator (generator) which in turn is connected to the batterypack and electric motor through an electronic control unit. Thisscheme allows the electric motor to get its power from either

battery pack or the alternator or both as per the battery state ofcharge and vehicle acceleration requirements [4-6].

Advantages: Low emission drive is possible most of the time

Engine can run more efficiently because it is not directlyconnected to the drive train.

Flexibility of location of engine-motor set Suitability for short trips.

Disadvantages:The vehicle needs a full-sized electric motor, an electric

generator and an IC engine, each of which can supply the

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required power for the vehicle.The vehicle is only driven by the electric motor, which

places great constraints on the battery pack and inparticular requires large battery capacities.

All three drive train components need to be sized formaximum power for long distance, sustained, high speed

driving. This is because the batteries will exhaust fairlyquickly, leaving ICE to supply all the power.

B. Parallel HEV ConfigurationIn the parallel HEV configuration there are two power paths

for the drive train, while one comes from the engine the othercomes from the electric motor. During short trips the electricmotor can power the vehicle, while during long drives the IC

engine can power the vehicle. The vehicle can thus have engineonly, motor only, or a combination of engine and motor mode

of operation. The electric motor can also assist the engineduring hill climbs and vehicle accelerations, thus the rating ofthe IC engine can be reduced. This configuration is illustrated

in Figure 2.In parallel HEV configuration, the drive train is connectedto the electric motor and engine through a mechanical couplingor an angle gear. These vehicles do not require a generator (as

in the case of series HEV configuration) and they can beconnected to an electric grid (off-board) for recharging the

batteries. The electric motor can be made to act as generator viaa mechanical clutch which can then be used for regenerativebraking. Both the gas-powered engine and the electric motor

can turn the transmission simultaneously, and the transmission,of course, turns the wheels. The fuel tank and gas engine andthe batteries and electric motor connect independently to thetransmissionas a result, in a parallel hybrid; both the electric

motor and the gas engine can provide power.Advantages:

In this configuration, the battery size can be small, as boththe engine and motor are connected to the drive train.

The performance is very much comparable to conventionalvehicles due to dual power sources.

The constraints on the battery pack and the electric motorare relaxed in this configuration.

Disadvantages:The vehicle cannot get full acceleration support from the

electric motor when the battery pack charge is low.The control complexity increases significantly, because the

power flow has to be regulated and blended from twoparallel sources.

The power blending from the ICE and the motornecessitates a complex mechanical device.

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Figure 2. Parallel HEV drive train

C. Dual Mode HEV ConfigurationDual mode hybrid vehicles are parallel hybrids, but differ

from them in the aspect that an alternator (generator) is coupledto the IC engine that charges the battery. During normal

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operation, the IC engine turns both the drive train and thegenerator, which in turn feeds the battery pack through theelectronic control unit. During full-throttle acceleration, the

electric motor gets power from the battery and assists the ICengine to attain the requested acceleration. Choosing a full sizeelectric motor, which uses the IC engine only for charging the

battery and occasionally for turning the wheels, can reduce tailpipe emissions and this can be achieved with the help of amechanical clutch. This configuration exhibits dual capability

and hence the name dual mode HEV configuration. Theschematic of the dual-mode HEV configuration is shown in

Figure 3.

Figure 3. Dual Model HEV drive train

Advantages: It has both the advantages of the series and parallel

configuration.Disadvantages:

It needs more components such as an electric motor, anelectric generator, an IC engine and a battery pack, for its

operation which makes it more expensive.

III. DESIGN AND IMPLEMENTATIONA. Mechanical Design

Mechanical design of the proposed HEV starts with thefunctional block diagram, and design of the chassis, the majorcomponents involved in prototyping and the parts constructed.

Functional block diagram: A simple and comprehensiveblock diagram is presented to manage the workflow of this

study. In designing the prototype of the hybrid car,mechatronics design approach illustrated in Figure 4.

Figure 4. Functional block diagram of the proposed HEV

Chassis design: Chassis is the base part of the mechanical

design. The chassis took shape of only the rear part of theactual vehicle, this is to consider the place where all the main

components will reside and thus reduce the manufacturing costof the prototype. The dimensions are calculated by consideringthe general size of the components after research conducted.

The angle aluminum is considered as the main material for theconstruction of the chassis. There are few reasons why thisangle aluminum is very suitable for the construction of the

prototype such as light weight, easy to connect, high strengthetc.

Gasoline Engine: The selected engine is BG-328 brushcutter, with peak power 0.81kW. Important advantages of this

engine include fuel efficiency and weight. A detailedspecification is provided in Table I.TABLE I. SPECIFICATIONS OF GASOLINE ENGINE

Model BG-328Engine type 2 cycle, single cylinder, gasoline engine

Displacement 30.5 ccMaximum output 0.81kW

Fuel Mix fuel of gasoline and 2 cycle oilDimension (LxWxH) 345 X 280 X 401 mm

Dry weight 9.4kgSupplier OTONANI Co. Ltd

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DC motor:The type of motor used can vary depending onthe power system of the vehicle and its size. Current internal

combustion hybrid cars tend to use AC induction motors due toboth the power requirements and the generally increased

efficiency over commutated DC motors. However for smaller

low-speed vehicles the desire would be to use some form ofDC motor to decrease the overall complexity of the vehicle.The use of a DC motor would reduce the power conditioning

546requirements by eliminating the need for an inverter from DCto AC power. Despite being slightly less efficient, the reducedexpense and balance of plant obtained by using DC motors

makes them more suitable for low speed hybrid vehicles. Thereare some other mechanical parts included such as SLA battery,

alternator and wheels, transmission, belting, chain etc.

B. Electrical DesignMicrocontroller is used to control the electrical part of the

design. There are many types of microcontrollers of differentplatforms in the market with various features. These include

Atmels AVR, Intel compatible 8051 from variousmanufacturers, DS80C400 Networked microcontroller from

Dallas Semiconductors, and the famous PIC seriesmicrocontrollers from Microchip [7-9]. In this study the

microcontroller used is PIC 16F877A.Electrical system functional block diagram: Every motor

control circuit can be divided into the drive electronics and thecontrolling software. These two pieces can be fairly simple orextremely complicated depending upon the motor type, thesystem requirements and the hardware/software complexity

trade-off. The drive electronics as well as the controlling

software will be explained and discussed thoroughly. Thefunctional block diagram of the electrical system connection ofthis study is shown in Figure 5. It is fairly simple in term oflinking as much of the controlling is done by software. The

main connection is between the motor and the battery, and thebattery to the alternator. The potentiometer is be used as means

of controlling the speed of the motor.Figure 5. The functional block diagram of the electrical part of

the proposed HEV

Pulse-Width Modulation is critical to modern digital motorcontrols. By adjusting the pulse width, the speed of a motor canbe efficiently controlled without larger linear power stages. PIC

16F877A has hardware PWM modules on them. Thesemodules are built into the Capture/ Compare/PWM (CCP)

peripheral. CCP peripherals are intended for a single PWMoutput, while the Enhanced CCP (ECCP) is designed toproduce the complete H-Bridge output for bidirectional

Brushed DC motor control.To reverse the direction of rotation of motor, it is necessary

to reverse the polarity of the voltage on the motor. Thisrequires the use of an H-Bridge. An H-Bridge schematic

diagram is shown in Figure 6. The application of H-Bridge willbe explained in later section of the chapter. Using this

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topology, it is possible to provide variable speed control in bothdirections.

PIC 16F877A Microcontroller: It has 40 pins and 5 inputoutput(I/O) ports. Port A consists of 6 pins which can be set up

as either digital I/O or analog inputs. Port B is an 8-pin portwhich can be used for both digital I/O operations and in-circuit

debugger (ICD) operations. Port C, on the other hand, is a 5-pin multi-functional port, which can be used for digital I/O, ascapture-compare (CCP) input, or pulse-width modulation

(PWM) output. Moreover, it can be used as universalasynchronous receiver/transmitter (UART) for serial

communications. Port D is an 8-pin port, which can be used forboth digital I/O as well as parallel slave port (PSP) functions.

Finally, Port E is a 3-pin port, which is used for externalmemory connections. The clock is provided by a crystal

oscillator. Supply voltage VDD = 5V is regulated DC Voltage.The connections are as shown in Figure 6. VSS = 0V is the

ground. The crystal oscillator is connected to the ground with30 pF capacitors.

PIC 16F877AFigure 6. The clock and input connection

Battery voltage indicator: The circuit in Figure 7 below is avoltage analyzer that gives an audio-visual indication of the

battery voltage level and also warns about the critical voltagelevel at which the battery require charging. This circuit is

integrated just as an indication. It is separated from the maincontrolling circuit as the main circuit that consists of

547microcontroller can only take 5V power supply and the batteryvoltage indicator work with 12V power supply. It also feature

switch on-off to easily interface between the user and the

circuit.Figure 7. The battery voltage indicator circuit

IV. RESULTS AND DISCUSSIONThe design of HEVs permits great flexibility, allowing the

designers to optimize for a number of different benefits, suchas fuel economy, emissions, cost of the vehicle, and safety.

Figure 8. The proposed HEV prototype

At start, the engine must be put to ON mode and the voltageindicator switch turned on to check the battery voltage beforethe operation can be run by the DC motor. It means that, if thebuzzer of the voltage indicator did not produce any sound and

no LED lights up, the batteries have insufficient voltage topower the motor and thus cannot run in motor-mode and must

be recharge before can be used. In other condition, providedthere is enough voltage to move the electric motor, the mode ischanged to motor-mode instead of engine-mode. This is

detected by the software program that controls the on-off of thebattery charging process by analyzing the analog input from the

battery.The program will start to recharge the battery at voltagevalue = 11.8V. The program is also set to be able to moveforward and reverse by a button switch as a mean to do so

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V. CONCLUSIONSAn HEV intelligently gets around the individual problems

associated with the gasoline engine and the electric vehicle. Itdiminishes the production of emissions and the use of fuel. The

problem of batteries for the electric vehicle is conquered. An

HEV charges itselfit never has to be plugged in. When not inuse providing power, the motor can run as a generator totransfer energy from regenerative braking and from the

gasoline engine to the batteries.The only recharging necessary is refueling by going to the

gas station. Also, there is not the same demand on the batteriesas there would be in an electric vehicle, where the batteriesmust store all the energy the car needs. These batteries are

smaller, and only have to be able to provide for the high-poweruses. Similarly, the engine for a HEV is smaller than it would

be in a traditional car, as it doesnt have to provide as muchhorsepower.

ACKNOWLEDGMENT

This research work is supported by IIUM under endowmentproject EDWB11-044-0522.REFERENCES

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