Thesis Abstract

This project work is on the development of a solar powered car. It involves the design and fabrication of a solar powered car with a carrying capacity of two individuals and a maximum speed of 30 km/hr, which runs entirely on a stand-alone solar system. The car is a unique prototype sedan car. It is design with dimensions of 3 meters’ x 1.6 meters. The maximum load carrying capacity of the vehicle is 700 kg and it requires a driving force of about 4.3 kW. The solar car uses a clean engine made up of direct current brushed motor rated at 13 kW output power and sourcing its required power from the stand-alone system. Cars running on fossil fuel do not only contribute to global warming and pollution, but they also have high running and maintenance cost, due to these challenges, the project seeks to alleviate these problems by adopting the use of alternative renewable source of energy for land transportation.

KEYWORDS Batteries, DC Motor, Energy, PV, Solar Car, Weight.

NB This Project won the best award at National Student Project Exhibition organized by the Nigerian Institution of Mechanical Engineers (NIMechE) at her 28th International Conference, Abuja

Thesis Overview

I. INTRODUCTION

The earth continues its increase in human population, with projections from the United Nations estimating an addition of 2.6 billion people to the planet. This statistic poses a greater demand on our already depleting traditional energy reserves. The automotive industry is one of the largest dependants of traditional energy source. Most of its technologies are built to run on fossil fuels which is unsustainable and hazardous to the environment. The considerable risk it poses to society has necessitated the automotive industries to also seek for alternatives, thus probing researches into renewable energy technology. Solar energy is a product of the sun’s radiation through brilliant light and heat. It is a perfect energy gotten from the sun. Innovations like, photovoltaic, solar heating, solar thermal and counterfeit photosynthesis have made feasible the sapping of the energy from the sun. These systems are usually referred to either active or passive technology depending upon the capturing and circulation mode. Active technology includes the utilization of photovoltaic, this is the most favoured amongst other technology because of its efficiency. The force of the sun is being outfitted to turn the wheels of the vehicle utilizing sunlight based cells (photovoltaic). Revealing this utilization of solar energy and numerous different applications, Tarik, Srea, Monzurul, and Khairul in 2012 stated that PV generation (a dynamic system of harnessing the sun’s energy) turn out to be twofold at regular intervals, expanding by a normal of 48 percent every year since 2002. Solar energy has been the most effective source for fuelling electric vehicles in contrast with other renewable energy source. This energy is harnessed and utilized specifically in form of electrical energy to power car. Md. and Md. in 2012 described a solar powered car as a type of electric car controlled by this sun based power. The energy is acquired from PVs frequently situated at the rooftop or surface of the car. The PV cells complete the energy transformation of the sun to an electrical energy. Solar powered car comprises of solar panel, charge controller, battery and engine(motor). Dissimilar to fossil fuelled car, their engine has no emanation and can either be Alternating current (AC) or Direct current (DC) engine. Solar powered cars are yet to be commercialized in vast volumes. Nations like Germany, US, China and India are working towards its commercialization. Presently, they are fundamentally utilized as sport cars and for practical demonstrations or exhibitions.

Sun exclusively relies on PV cells to transform Sun rays into power. PVs are product of semiconducting materials usually silicon. Silicon is refined, handled and encased in a treated glass for security purposes. The application of PV technology in the automotive industries has greatly contributed to the recent research feet gained in green technology. As more attention will be lavished on reducing the severe hazards accompanying green house emissions, research in this area will not cease. Nigeria has taken a foothold in this participation. Therefore, the need to develop her model of transportation utilizing renewable energy becomes imperative. The advent of solar cars has not only provided the automobile industries a clean energy, but an efficient and cost effective technology and this project will focus on building one using locally available components and materials.

II. OBJECTIVE

To design and develop a prototype solar powered car which will be clean, reliable, economical and environmental friendly. The car is design in a scale of around 3 meters’ length x 1.6 meters’ width and would only carry two people alongside it accessories which include batteries, DC motor, charge controllers and PV array. It uses cascaded batteries of 48 V and 150 Amps hour total rating, and a motor controller to vary the speed, the batteries receive charges from 3 pieces of PV panel each of 180 W (540 power wattage). The chassis of the car are fabricated using local content materials to cut expenses and easily control the weight.

III. COMPONENT DESCRIPTION

The structure of the solar car is sectioned into chassis and body, transmission system, suspension system and wheels, steering system (which are considered as the mechanical components) and electrical/solar components. The purpose of structuring is to provide explicit details of the research work.

Design of the car with Solid works software

A. Chassis and body:

Chassis is the backbone of the vehicle since all the mechanism of the solar car like the transmission system, axle, wheels and tyres, suspension and also the control systems and electrical components are mounted on the chassis frame including the body. The different types of chassis; ladder, space frame, monocoque and backbone chassis used in automobile were considered before picking the one that suits our design considerations using the solar car designs and assumptions in perspective, the space frame chassis is suitable to the specifications and materials to be used. The space frame chassis utilise dozens of circular-section tubes and square-section tubes positioned in different directions to give mechanical strength against forces from anywhere. The tubes are welded together to form a very complex structure with maximum strength in any direction.

B. Transmission system:

Solar vehicles do not entail the normal Orthodox transmission system with several speed. The polarity of the electric motor is essentially reversed when the vehicle need to be reversed. This implies the direction of rotation of the electric motor and this is done using a gear selector lever, which simply has the positions; Neutral, Forward and Reverse and the speed can be regulated with the accelerator pedal. Based on the design specification, the rare axle differential is connected to the rare wheel from the electric motor positioned centrally in the chassis to relay and convert the rotation motion to linear motion thus enabling the car to move forward.

C. Suspension system:

This system is a major automobile subsystem which is a mechanical assembly that connect each wheels to the body. Basically, the suspension system functions as to isolate the car body from the vertical motion of the wheels as it travel over tough road surface since the wheel assembly is connected through a movable assembly to the body.

Suspension system in solar vehicles consists of the wheel assembly, the spring which support the weight of the car. In addition, a shock absorber (sometimes a strut) which is in effect a viscous damping device.

Solar cars have a very stiff suspensions designed to prevent damage to the frame in the event of a large jolt. For the front wheels, almost all solar cars utilize double A-arm system and it has normally completely independent suspension. It is a more compact system that lowers the vehicle hood resulting in greater visibility and better aerodynamics

D. Steering system:

This system is one of the major subsystems required for operation of the car. It provides the driver control of the path of the car over the ground.

It consists solely of mechanical means for rotating the wheels about a nominally vertical axis in respond to the rotation of the steering wheel.

The rack and pinion steering system is considered due to design specification. It uses the steering column, steering wheels and steering shaft to transfer the drivers turning effort to gears in the steering gear assembly.

E. Electrical/Solar components:

This constitutes the solar array, power train and the telemetry. The power train comprises of the high voltage system (solar array, battery pack and motor) and low voltage systems (sensors, motor controller, lights and drive controller). The low voltage systems are carefully design following standard electrical and power circuits

Electrical circuit for the motor controller

Working Principle of the Vehicle

The vehicle is a solar powered car. Unlike the I.C engine powered cars, it runs on electrical energy instead of petrol or diesel. The simple working principle of the car involves; energy being harnessed from the sun via solar panels (PV arrays) and used to charge a battery bank which stores this energy in form of electrical charges, the battery bank then supplies this energy to an electric motor which is connected to the vehicle wheels by means of the transmission ( in this case a rear axle differential assembly).

IV. RESULTS AND DISCUSSION

The simulations carried out on the car include Computational Fluid Dynamics (flow simulation), frame stress analysis, frame displacement analysis. This was done with the use of Solidworks software.

Results summary for Computational Fluid Dynamic (Flow Simulation)
Value(N) Average Value(N) Minimum Value(N) Maximum Value(N) Delta(N) Criteria(N)
-234.0410074
-238.3399807
-246.3935986
-233.9750293

12.4185693

16.08258443

Analysis Interval=20
Iterations=40

Graph of Forces Acting on the Frame against Number of Simulation Iterations

Flow Trajectories One(1)

Flow Trajectory Two(2)

Name Type Min Max
Stress1 TXY: Shear in Y Dir. on YZ Plane 0 N/m^2
Element: 107 4.87306e+009 N/m^2
Element: 535

static simulation-Study 1-Stress-Stress1

Frame Stress Analysis
Name Type Min Max
Displacement1 URES: Resultant Displacement 0 mm
Node: 21 24.8161 mm
Node: 179

static simulation-Study 1-Displacement-Displacement 1

Frame Displacement Analysis

The developed solar powered car

The developed solar powered car(the interior view)

The results of the flow simulation (CFD), the total drag force obtained is 15N, which is moderate and only noticeable at speeds above 30km/hr. The displacement analysis (FEA) carried out on each critical element (members) of the frame/chassis reveals that the frame is stable and will perform efficiently at the specified conditions.

During driving of the developed Solar Car, the Car was able to overcome the starting torque of 37.03 Nm. This justifies that the developed Solar Car passes the initial static road condition test.

V. CONCLUSION

Haven found answer to the research questions which lead to the development of a Solar powered car. It is clear that the project was able to get acquainted with this new area of photovoltaic solar energy application. Components and equipment purchased for the development of the solar-powered car were fully utilized in building and testing the car.

RECOMMENDATION

This project needs improvement in other to achieve higher performance;

I. Continuous works especially on the electrical installations and control systems is necessary. Further testing to ascertain the efficiency of the car is also recommended.

II. In subsequent design of the solar-powered car, to reduce the weight and drag force, lighter material such as aluminium should be used in building the frame/chassis. A more efficient and lighter electric motor should be utilized. Accessories such as lighting systems, wipers, and charging outlets is an important area to look into, government and private companies should seek to build such charging stations.

III. Finally, solar technology is an alternative that can be commercialized to replace non-renewable energy sources. It is also very necessary to consider factors such as weather, environment factor, reliability of solar module and load to develop effective and efficient solar technology.