A

Project plan on

Design and Development of a prototype Plug-in Hybrid Electric Vehicle

for international student competition

Formula Student 2013, Silverstone UK

Undertaken by the students of

Indian Institute of Technology Roorkee ROORKEE – 247 667 (UTTARAKHAND)

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Table of Contents Project Summary

1. Team IIT Roorkee Motorsports – Background and introduction

1.1 First Project : Race car development for Formula SAE Australasia 2011

1.2 Specifications of 2011 vehicle

2 Introduction to Formula Student and Formula SAE Competitions

3 Formula Student UK 2013

4 IIT Roorkee and Formula Student UK 2013

5 International Status of Hybrid Technology

6 National Status of Hybrid Technology

7 Importance of proposed project in context of current status

8 Work Plan

9 Vehicle Development Methodology

9.1. General

9.2. Engineering &Design

9.3. Fabrication & Assembly

9.4. Testing

10 Design of the 2013 Car

11 Specifications of the 2013 Car

12 Project Completion Status 12.1. Work already completed

12.2. Work to be done next

References

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Project Title Design and development of a prototype Plug-in Hybrid Electric Vehicle (PHEV) for international student competition Formula Student UK

2 Chief Faculty Advisor Dr. Pramod Agarwal 3 Designation Professor and Head 4 Organisation Department of Electrical Engineering, Indian

Institute of Technology Roorkee 5 Telephone, Fax, email +91-1332-285231, 285069 / +91-1332-27560 /

pramgfee@iitr.ernet.in 6 Industry Advisor Mr. Tejas Kshatriya 7 Designation Associate Vice President, Hybrid Electric

Technology 8 Organisation KPIT Cummins Infosystems Ltd. (Pune, India) 9 Telephone, Fax, email +91-9822217997,

tejas.kshatriya@kpitcummins.com Major Students Involved in the Project

10 Student Name Digendra Singh Rathore 11 Branch / Year Mechanical Engineering, B.Tech. 4th year 12 Role Team Leader and Project Manager 13 Telephone, Email +91-8791194290, dsr.iitr@gmail.com 14 Student Name Prashant Arora 15 Branch / Year Mechanical Engineering, B.Tech. 4th year 16 Role Chief Mechanical Engineer 17 Telephone, Email +91-9675449689, prashant.15oct@gmail.com 18 Student Name Akshay Sarin 19 Branch / Year Electrical Engineering, B.Tech. 4th year 20 Role Chief Electrical Engineer 21 Telephone, Email +91-9557830877, 81sarin@gmail.com 22 Major Project Sponsors Oxigen Services Pvt. Ltd.

Bajaj Auto Ltd. ANSYS India Ltd. Rockman Industries Ltd. Unitech Machines Ltd. Bender Corporation (Germany) Xilinx Corporation (USA) Sensata Technologies Ltd. (Netherlands) Wilwood Brakes Ltd. (USA) Quaife Engineering Ltd. (UK)

23 Major Alumni Supporters

Mr. Ashok Soota (Chairman, Happiest Minds Technologies Ltd.)

Mr. Pramod Saxena (Chairman, Oxigen Services Ltd.)

Mr. Sunil Pahilajani (Managing Director, Greaves Cotton Ltd.)

Mr. Ravi Sharma (Former CEO, Adani Power Ltd.

Project Summary

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1. Team IIT Roorkee Motorsports – Background and introduction

Formula Student team of IIT Roorkee is a group of engineering students of different academic departments from IIT Roorkee who work together in design and development of prototype race cars and participate in educational engineering design competitions at international level. Team was founded in August 2010 and since then it is the most active student group of the campus engaged in engineering and design projects in the automotive domain. Present team consists of more than 35 students from second, third and final years of Electrical and Mechanical engineering. Team undertakes entirely student managed projects involving designing, fabrication, assembly and testing of the car besides project management, sponsorship, marketing and web designing. The team structure is as follows:

The Electrical and Mechanical streams are further divided into respective sub-teams such as Power-train, FPGA, Brakes, Vehicle Dynamics, CAD/CAE, Aerodynamics, Body and Ergonomics, etc. Advisors associated with the project are :

Dr. Pramod Agarwal Professor and Head Department of Electrical Engineering

Dr. Manoranjan Parida Professor and Head Centre for Transportation Systems (CTRANS)

Dr. Akshay Dvivedi Assistant Professor Department of Mechanical & Industrial Engineering

Mr. Tejas Kshatriya Associate Vice President Electric - Hybrid Technology KPIT Cummins India Ltd.

Team Leader / Project Manager

Junior Project Manager

Chief Engineer - Electrical

Senior Engineers

Junior Engineers

Chief Engineer - Mechanical

Senior Engineers

Junior Engineers

Workshop Manager

Marketing & Sponsorship Executives

Designers and Website Manager

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1.1 First Project : Race car development for Formula SAE Australasia 2011 In the first project, 20 students were part of the team which developed an IC engine based race car and successfully participated at the international level in the competition “Formula SAE Australasia” held at Victoria University in Melbourne, Australia from 15 – 18 December 2011. It was organised by Society of Automotive Engineers - Australasia (SAE-A) in association with Ford, Holden and Toyota. Total 30 international teams from prestigious universities of Australia, New Zealand, Japan, Malaysia, UK and India were registered in the event and IIT Roorkee was the only Indian team in the final competition. Team’s achievements in the debut year are as follows:

IIT Roorkee’s car secured the first position in fuel efficiency. Secured 6th position in cost presentation. It became the first Indian car in the history of Australian competition to finish the 32 laps of

final 22km endurance run. Overall position was 16th which was considered as an excellent performance by any team

participating for the first time. This car was also exhibited at the design pavilion of Auto Expo 2012 held at New Delhi in January 2012 where it attracted much appreciation and motivation from visitors including industry engineers and people from automotive companies.

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1.2 Specifications of 2011 vehicle

Dimensions Front Rear Overall Length, Width, Height 2900mm long, 1600mm wide, 1250mm high Wheelbase 1700mm Track Width 1400mm 1350mm Weight with 68kg driver 156 kg 171 kg

Suspension Parameters Front Rear Suspension Type Double unequal length A-Arm. Pull rod

actuated horizontally oriented spring and damper

Double unequal length A-Arm. Push rod actuated

vertically oriented spring and damper

Tire Size and Compound Type 20x7-13 R25B Hoosier 20x7-13 R25B Hoosier Wheels (width, construction) 6 inch wide, 1 pc Steel Rim, 30mm neg.

offset 6 inch wide, 1 pc Steel Rim,

30mm neg. offset Center of Gravity Design Height 260 mm above ground Suspension design travel 35mm bump/ 50 mm rebound 35mm bump/ 50 mm rebound Wheel rate (chassis to wheel center) 17 N/mm 21 N/mm Roll rate (chassis to wheel center) 1.0 degrees per g Sprung mass natural frequency 2.0 Hz 2.2 Hz Motion ratio / type 1.2 / progressive 1.0 / progressive rate Camber coefficient in bump (deg / m) 32 deg / m 32 deg / m Camber coefficient in roll (deg / deg) 0.5 deg / deg 0.8 deg / deg Front Caster and adjustment method 5 degrees non-adjustable Front Kingpin Axis 1 degrees non-adjustable Kingpin offset and trail 5mm offset, 12mm trail Static Akermann and adjustment method 5% adj. via tie rod length, range from 10% anti to 20 % pro Antidive / Anti Squat 30% 30% Roll centre position static 55mm above ground 80mm above ground Roll centre position at 1g lateral acceleration

52mm above ground, 50mm toward laden side

82mm above ground, 30 mm toward laden side

Steer location, Gear ratio, Steer Arm Length

Front steer, rack 4" for 1.75 turns of pinion. 60mm steer arm

Brake System / Hub & Axle Front Rear

Rotors Fixed, Cast Iron, hub mounted, 220 mm dia.

Outboard Fixed, Cast Iron, hub mounted, 220 mm dia.

Master Cylinder 16mm bore front / 19mm bore rear Calipers Dual piston, 18mm dia., floating Dual piston, 18mm dia.,

floating Hub Bearings Angular contact bearings (80mm OD

and 40 mm ID) Angular contact bearings

(80mm OD and 40 mm ID) Upright Assembly CNC 6061-Al, integral caliper mount CNC 6061-Al, integral caliper

mount Axle type, size, and material Rotating axle, 40mm dia, 6061

Aluminum Rotating axle, 40mm dia

6061 Aluminum

Ergonomics Driver Size Adjustments Seat inserts, fixed steering wheel, Pedals fixed Seat (materials, padding) glass fiber lay-up, padded lumber and knee protection, 80mm foam head

support Driver Visibility (angle of side view, mirrors)

225 degree side visibility, no mirrors

Shift Actuator (type, location) Manually actuated 4-bar linkage, left side cockpit mount Clutch Actuator (type, location) Foot pedal, cable actuated

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Instrumentation Dash mounted temp, oil and fuel gauge, tachometer

Frame Frame Construction Tubular space frame Material 1020 steel round tubing 16mm to 25mm dia Joining method and material TIG welding with MS 1.6mm filler Targets (Torsional Stiffness or other) 1600 N-m / deg Torsional stiffness and validation method 1700 N-m/deg via FEA Bare frame weight with brackets and paint 38 kg

Crush zone material Standard Impact Attenuator Crush zone length 250mm

Powertrain Manufacture / Model Royal Enfield 500cc Electra Unit Construction Engine 2011 Bore / Stroke / Cylinders / Displacement 84mm bore / 90mm stroke / 1 cylinder / 499 cc Compression ratio 8.5:1 Induction (natural or forced, intercooled) Natural Throttle Body / Mechanism 32mm, butterfly valve throttle

Max Power design RPM 5250 Max Torque design RPM 3800 Min RPM for 80% max torque 2700 Fuel System (type) fuel injection Fuel System Sensors (used in fuel mapping) Air Temp, Throttle Position, Lambda sensor, Map sensor

Fuel Pressure 3-5 bar Injector location 75mm before and pointing toward intake valve Intake Plenum volume and runner length(s) 1200 cc, 100mm runner

Exhaust header design Stainless steel tubing, routed through side into muffler Effective Exhaust runner length 900mm - 1200mm Ignition System Dual spark Ignition Timing 18 deg BTDC max advance Oiling System (wet/dry sump, mods) Wet sump Coolant System and Radiator location Air cooled Fuel Tank Location, Type Floor mounted between firewall and engine, aluminum tank

(8 Liters) Muffler Single glass pack muffler, 3-4 liter volume

Drivetrain Drive Type Steel chain Differential Type Quiafe ATB limited slip, Final Drive Ratio 2.11 Vehicle Speed @ max power (design) rpm 115 km per hour

2. Introduction to Formula Student and Formula SAE Competitions Formula SAE (USA, Japan, Australia, Brazil) and Formula Student (UK, Germany, Italy) are a series of world's most established and prestigious educational automotive engineering design competitions which are run by Society of Automotive Engineers (SAE) and Institution of Mechanical Engineers (IMechE) in partnership with leading automotive companies. Hundreds of student teams from the renowned universities of more than 30 countries participate in these events and showcase their talent in

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automobile engineering by designing, building, testing and racing their student made Formula-1 style race cars. The rules of the competition ensure a high standard of safety while simultaneously encouraging the innovation and originality. There is no restriction on the powertrain type and the students can bring hybrid and alternatively fuelled vehicles. In addition to racing, students have to present the car to a panel of industry professionals for an in-depth discussion and critical analysis of the design, engineering, aesthetics, ergonomics, manufacturability, maintainability, reliability, costs and marketability of the vehicle. The cars are judged in a series of static and dynamic events including safety check, technical inspection, sustainability, marketing presentation, engineering design, solo performance trials and high performance track endurance. Generally these projects form part of the students’ engineering degree course and counts towards their final marks.

3. Formula Student UK 2013 Formula Student UK is one of the largest events in the competition series and is organised by Institution of Mechanical Engineers (IMechE) in partnership with Jaguar Land Rover, Mercedes AMG, National Instruments, Shell and Robert Bosch. A total of 149 student teams from 32 countries have registered for Formula Student 2013 who would compete and race against each other at the renowned Silverstone Circuit, the home of British Grand Prix from 3 – 7 July 2013. The point scoring

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pattern would be as follows :

Business Presentation 75 Engineering Design 150 Cost and Sustainability 100 Acceleration 75 Skid pad 50 Autocross 150 Fuel economy / CO2 emissions 100 Endurance 300 Total 1000

4. IIT Roorkee and Formula Student UK 2013 Keeping in mind, the global technology developments in automobiles, IIT Roorkee student team is developing a Plug-in Hybrid Electric Vehicle (PHEV) to participate in FS – UK 2013. IIT Roorkee’s design plan has already been accepted by the Institution of Mechanical Engineers (organising agency) and it is the only team with a hybrid car among 149 international entries. Consumption of fossil fuel and Global Warming are two major problems being faced by the world today; and automobile sector is a major contributor in this regards. In India, cost of petrol has been escalating steeply for the last 2 years and has made private transportation very costly. To cope with this problem global automobile industry has proposed various solutions, the most acceptable and feasible among which is petrol - electric hybrid power train in the vehicles. In such systems battery is used as a prime source of energy to run motor (motor has better efficiency than engine as a prime mover) and engine is used to extend the range of battery operation. Regenerative Braking (RB), high efficiency motors, small engine size and an efficient control strategy can yield a high performance hybrid vehicle with low fuel consumption and reduced emissions. Being the students of IIT Roorkee, which is the institute of national importance, it’s our endeavour to work in those areas of engineering which may lead to its technical and social empowerment in the global scenario. On basis of SWOT analysis, it was decided that the hybrid technology is beneficial for India and thus IIT Roorkee students should get involved in related projects so that a platform may be created for future students to work, learn and innovate in this area.

STRENGTHS

Hybrid Vehicles are more fuel efficient through constant engine operation and Regenerative Braking.

Lesser running costs. Produces less pollutant as less fuel is burnt. Quieter and better drivability.

WEAKNESS

High Initial Costs. The electric supply grids in India, in the

present form, may not support direct charging of Plug-in Hybrid Electric Vehicles.

OPPORTUNITIES

Increasing fuel prices, pollution and fossil fuel consumption demands greener and sustainable solutions.

Commercial hybrid vehicles are already in the Global market but there is no Indian

THREATS

In the short term, market may not accept the technology due to high initial costs.

The increasing cost of domestic electricity may not bring the running costs as lower as expected.

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product. Hence this opens ambient opportunities for R&D in India.

Indian Govt. has launched the National Mission on Hybrid and Electric Mobility to encourage R&D in this field.

This competition allows university students to develop a hybrid vehicle as per the same set of rules and constraints and then compete against each other. Therefore it was decided that this is the best platform available to judge the quality of our hybrid car with respect to standard criteria; also the competition against other international teams would reveal the different areas where the product and knowledge areas need to improve.

5. International Status of Hybrid Technology At international level significant research has been done in the field of hybrid automobiles. The first electric hybrid car was made in 1901 by Ferdinand Porsche [1] however the first commercial electric hybrid was Toyota Prius launched in 1997 in Japan [2], later followed by many global companies with further developments in technology and improved efficiency. Presently there are over 22 different commercial hybrid vehicles [3] available in the global automobile market. The hybrid car market is ramping up. Hybrid sales in the US grew exponentially, from 9,500 in 2000 to 350,000 in 2007[4].same is the scenario of other countries like Netherland, the Japan and Germany. In 2011, USA’s research budget for Hybrid vehicles was $3 billion[6]. Some of the prominent research institutes in the field of Hybrid Electric Vehicle are:

International Energy Agency US Department of Energy Automotive Engineering Research Institute China Automotive Technology and Research Centre National Renewable Energy Laboratory ,USA

However, at university level, the first electric hybrid car for the Formula Student competition was made in 2006 by the Thayer School of Engineering, University of Dartmouth. In the past 8 years, about 30 university student teams from all over the world have designed and developed their own electric hybrid vehicles. Some of the universities involved are:

Yale University, USA Colorado State University, USA Georgia Institute of Technology, USA McMaster University, Canada Lund University, Sweden National Chiao Tung University, Taiwan MADI State Technical University, Russia Politecnico Di Torino, Italy

6. National Status of Hybrid Technology In India, till now, only two companies namely Ashok Leyland and KPIT Cummins have launched their commercial hybrid automotive solutions. In case of Pure Electric, there are a few commercial products in the Indian market for quite a long time, namely Mahindra Reva in 4-wheeler category and 2-wheeler electric scooters from the companies Electrotherm Ltd., Hero Electric and many others. But pure electric vehicles are still not popular due to higher cost and poor performance. In 4-wheeler category Toyota Prius, and Honda Civic Hybrid are available in Indian market but at higher

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costs as compared to normal petrol/diesel cars of the same category. Moreover, their technology has been developed outside India. The major Indian automobile makers are reported to have been working on hybrids but launch of any commercial product cannot be expected before 2015. Among Indian universities, only Delhi College of Engineering students have developed a small prototype of hybrid electric vehicle in 2006-07 for a similar international competition but unfortunately, the project could not sustain in the following years. Apart from this example, no other Indian university has revealed any such hybrid vehicle developed by the students for this competition.

7. Importance of proposed project in context of current status Current status of hybrid technology suggests that India is far behind developed nations such as

Japan, European countries, USA, etc in the R&D of hybrid automobile technologies. These technologies, at present, seem to be a possible solution to reduce the fossil fuel consumption and pollution produced by automobiles. This is very crucial in Indian perspective where a large percentage of the petroleum products are imported.

This project employs more than 35 engineering students of IIT Roorkee who would be encouraged to pursue higher studies in the field of hybrids and would be available as highly trained technical workforce ready to work in the areas of hybrids. Moreover, this project has a strong potential to deliver innovative technologies in hybrid domain. Successful completion of this project will open avenues of a new research area in IIT Roorkee and in future years it can be developed as a Centre of Excellence for research in Hybrids in India.

Indian Govt. has recently launched the National Mission on Hybrid and Electric Mobility to encourage indigenous technology, R&D, manufacturing and sales of commercial hybrid products. This proves to be the perfect time for IIT Roorkee and students and to start working in this area with an aim of serious research work in near future.

8. Work Plan

The entire project would be divided among different phases and the work involved in each phase would be divided among the team members as per the developed project plan.

Engineering & Design : This phase will start with a detailed study of the existing research and technology in the areas of hybrid vehicle, analysis of similar vehicles developed by other university teams for the same competition in past, followed by the entire designing of vehicle. This will include setting up the target vehicle specifications, performance goals, selection of motors, battery, engine-generator, wheels, brakes, calipers, sensors, fuses and other major and minor components of the vehicle. Apart from selecting the components on basis of target performance goals, simulations, availability and ease of operation, the most important job would be to develop the vehicle control strategy and its implementation through FPGA. A large number of simulations shall form the basis to obtain satisfactory results. An extensive study of previous vehicle designs for same competitions would be done to crosscheck our design.

Fabrication & Assembly : This phase would consist of the entire fabrication works related to the vehicle development. This would start with the assembly and simultaneous testing of powertrain components like motors, engine-generator, battery, vehicle controller, etc. This task would be undertaken by electrical team. Simultaneously, the mechanical team would undertake the tasks like welding of chassis, CNC machining of components, fabrication of intake-exhaust, suspension system steering system and others. After all the components/systems are fabricated and individually tested, they would be assembled as a single vehicle.

Testing and Debugging: Once the fabrication of the components/systems is complete, its testing and debugging would start. This would consist of testing the vehicle for certain compulsory tests that would be conducted during the competition like Brake Test, Rain Test, Acceleration Test, etc.

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Special arrangements would be done to imitate the competition conditions and it would be assured that the vehicle performs satisfactorily in all the specified tests.

9. Vehicle Development Methodology

1. General 1.1. Target Vehicle Specifications (Speed, Acceleration, Weight, Dimensions) The prototype vehicle would be developed such that it follows the rules of the competition while being competitive on the track against the vehicles developed by other university teams in the competition. For target performance of vehicle the test track is Silverstone Formula-1 circuit, UK. The track data (map, average and maximum speed, acceleration) and the target vehicle specifications of similar prototypes built in past would become the basis of vehicle specifications. While selecting the target vehicle specifications, other important parameters that would be considered are safety, sustainability, reliability, engineering design, cost, manufacturability, solo performance and high performance track endurance. Actual Test Track of 22 km (32 laps) Track description for Endurance Event:

Straights: No longer than 77.0 m (252.6 feet) with hairpins at both ends. There will be passing zones at several locations.

Constant Turns: 30.0 m (98.4 feet) to 54.0 m (177.2 feet) diameter. Hairpin Turns: Minimum of 9.0 m (29.5 feet) outside diameter (of the turn). Slaloms: Cones in a straight line with 9.0 m (29.5 feet) to 15.0 m (49.2 feet) spacing. Average speed should be 48 km/hr (29.8 mph) to 57 km/hr (35.4 mph) with top speeds of

approximately 105 km/hr (65.2 mph). 1.2. Vehicle Description The proposed series type PHEV is essentially an Electric Vehicle (EV) with the engine being used as a range extender. In series configuration, the engine does not directly powers the wheels; instead it drives a generator. The power generated by this engine-generator would run the prime mover (drive motor which directly powers the wheels) and/or charge the battery during the long range operations.

Time (seconds)

Figure 1 -

Figure 2 - Velocity profile of this category vehicles on the track

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Besides the normal mechanical components present in the car, it has extra components to incorporate the electric-hybrid feature. The electrical components would include: Electric motor coupled to the differential. Battery to supply power to electric motor. Electric generator, driven by engine, to generate power which will support the battery for long

range operations. Ultra-capacitor module (may be added) to provide boost to the vehicle and recover as much energy

as possible from the car through regenerative braking. Vehicle Control Unit (VCU) to be implemented on FPGA. Battery Management System (BMS) DC – DC Convertors Relays, Switches, High-voltage/low voltage wiring network.

2. Engineering & Design 2.1. Electrical 2.1.1. Motor & Controller The main component of the power-train network is the prime mover which in case of series hybrid

vehicle is the electric motor. The electric motor has to be selected such that it could cater to torque and power requirements for the vehicle at all the times given the maximum acceleration and velocity of the car.

The selection of the prime mover includes consideration of efficiency, ease of control, availability, cost, the ratings of continuous power, peak power and peak torque required for the vehicle.

The process of motor selection may require a number of iterations based on the differences between the available options and the requirements.

The motor controller should regulate the power from the battery and engine generator to feed power to the motor such that motor is run as per the command from the driver.

2.1.2. Battery with Battery Management System (BMS) The battery is selected for higher energy density and better cycle life. These factors suggest the use

of Lithium Ion battery. The design of the battery requires calculation of battery capacity. Important points for

consideration would be maximum discharge current during acceleration and maximum charging

Figure 3

Engine -

Generator Motor

Controller

Li-ion Battery Ultra-capacitor

Module

DC/DC

Vehicle

Controller

Acceleration,

Brake Pedal

Wheels

Motor

Mechanical

Power

Generator

Voltage

Control

BMS High Voltage Circuit

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current during regenerative braking and normal charging from generator. The battery would be connected to a Battery Management System (BMS) which is responsible for

balancing of voltage among each of the individual cells. It also prevents overcharging and undercharging of cells which is critical in case of Li-ion battery. Further the BMS continuously monitors the Battery State of Charge (SOC).

The BMS connects battery to contactors which are connected to motor controller. The contactors are turned on by the command from the motor controller and turned off through a matrix of protective switches applied at different points in the car.

There would be a pre-charge circuit which protects the controller from surge currents while connecting to battery pack. Also a discharge circuit is required to dissipate the remaining energy in the battery after the drive run is complete.

2.1.3. Generator Generator rating is decided on basis of the combined power requirements for the charging of

battery and vehicle run. The engine generator set will be connected to motor controller through a control unit to stabilize

the voltage of the engine generator set by setting the speed of rotation of the engine shaft. Whenever the battery SOC will fall below a critical limit, the engine generator unit will be turned

on, delivering a constant amount of power. A part of this power will be taken up by the motor controller for the purpose of running the motor and the rest will be utilized for the charging of battery module. The engine generator will turn off once the battery SOC crosses a particular value.

2.1.4. Vehicle Control System (VCS) A VCS monitoring the state of each of the individual powertrain components and responding to the actions or the commands from the driver is also required. This controller should generate control signals for turning the engine on/off, the ultra-capacitor module, charging of the battery, etc. The controller should also be able to modify the control strategy during the course of driving for the maximum efficiency of the car. VCS would be implemented on FPGA to accomplish the following tasks. When the vehicle is turned ON, the battery powers the motor with ultra-capacitor module

providing the necessary boosts required during rapid acceleration. The motor is coupled with the differential which drives the wheel shafts to move the vehicle forward.

During deceleration (braking) Regenerative Braking (RB) feature comes into action, in which the electric motor behaves as a generator and the mechanical energy is converted to electrical energy. RB recharges the battery and ultra-capacitor.

As soon as the battery charge falls below a predefined value, the engine is turned on which drives the generator. Energy generated by this engine-generator unit is used to power the prime-mover and the Battery. Once the battery is charged to a certain level, the engine generator set is turned off.

Different control strategies are employed during the different modes of operation i.e. Acceleration, Braking, Cruising.

2.1.5. Relays, Fuses, Switches and Protection System The vehicle will be equipped with protective relays, switches and fuses which are rated for maximum expected voltages and currents. The vehicle would be equipped with a protection system that should be able to detect any fault in the network and take necessary actions during the event of failure. Specifications and make of all the switches, fuses and other protection system components are specified in the competition rules. 2.2. Mechanical 2.2.1. Engine The objective of the engine is to drive the generator, since there is no heavy duty application of engine, it would be light single cylinder and its power rating should be slightly higher than generator, taking into account the factor of efficiency. The engine would operate at a constant RPM at the point of

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maximum efficiency. There may be load variation on generator which tends to disturb the RPM of engine, so a Voltage Feedback Engine Throttle Control System would be designed. It would take a feedback from the generator voltage and direct the servo motor to adjust the throttle such that it would maintain the required amount of fuel-air injection to provide necessary torque at the constant engine RPM (point of maximum fuel efficiency). 2.2.2. Drive Train The gear ratio will be decided while compromising between the top speed and acceleration requirement within the practical constraints of maximum torque and power ratings of motor, battery and system reliability issues. The type of chain/belt drive would be decided on basis of availability, cost, ease of use and efficiency of operation. Suitable sprockets will be designed with a material which can undergo high stresses during the operation. An automatic torque biasing Limited Slip Differential (LSD) would be used to ensure reliable torque distribution between the driven wheels. Drive Shafts would be selected to ensure minimum weight and reliability under constraints of availability. 2.2.3. Suspension System First, graphs would be prepared for tire characteristics such as lateral force vs. slip angle, tractive

force vs. slip ratio etc. using tire data on OptimumT. CAD models of all the components would be placed at respective positions as required in the

vehicle and parameters such as wheelbase, track width, Center of Gravity (CG) height, weight distribution front/rear, moment of inertia, etc would be calculated.

After above parameters are decided, suspension and steering geometries would be created taking into account proper packaging, ride comfort, roll center height, roll center migration, roll rate, roll gradient, camber gain during roll, steer camber, bump steer etc. as required for the vehicle. Accordingly suspension points, spring constant, A-Arms design, anti-roll bar design, etc are obtained. Selection of shock absorbers would be on basis of calculated spring constant and availability.

Shocker mounting on chassis would be governed by the packaging requirements. 2.2.4. Steering System Based on the steering angles and slip angles on front wheels, required tie-rod points would be

obtained. A-Arm design shall govern the length of tie rods. Placement of the rack would be governed by packaging constraints. Suspension and Steering design will go hand in hand. 2.2.5. Wheel Assembly Wheel of suitable offset would be chosen for packaging of suspension, brake and steering

components within the wheel, on account of availability. Wheel bearing type/diameter would be selected after dynamic analysis of loads on bearings. Rear wheel hub spline would be designed for shaft coupling. Stress analysis simulation of hubs and uprights would be done for selection of suitable material.

2.2.6. Brake System To determine the size of discs, brake torque distribution, size of master cylinders, etc first the

desired vehicle deceleration would be decided which is governed by performance requirements. The regenerative brake pedal design would involve placement of sensors, brake over-travel switch,

brake panic switch and inertia switch. Flexible brake lines of specific safety standards would be used. Brake pedal (and acceleration pedal) shape & size would be governed by the packaging

constraints.

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2.2.7. Roll Cage Design After fixing all the components in the assembly, complete CAD assembly is made which would be

used to design a 3-D wire frame sketch of the roll cage (chassis). The size and grade of steel tubes would be decided after the dynamic stress analysis of chassis. There should be proper triangulation and cross members for safe load paths, torsional rigidity and

stiffness.

2.2.8. Cooling All the components would be air cooled and hence ducting arrangements would be made to allow passage of air around battery, engine, motor, controller and other components which are prone to heating. 2.2.9. Body, Seat, Firewall After entire car is assembled along with the chassis in the CAD drawings, body panels are designed to provide necessary aesthetics and safety to components. Fiber glass/composites would be preferred to minimize the weight of the car. Car seat would be designed such that it fits into the driver cockpit and can accommodate the safety harness mounting. Firewall material and dimensions to be decided on basis of availability and packaging constraints. (A separate project is under progress in the mechanical engineering department which aims at developing bio-composites to be used for making the body of this car.) 3. Fabrication and Assembly 3.1. Electrical The first and the foremost task for the assembly of the power-train network would be to

synchronize the motor with motor controller taking care of necessary connections and installing the required sensors for the proper control of the motor. After the motor and controller are properly connected, the motor controller will be powered and it will receive control signals from the brake pedal, acceleration pedal and the vehicle controller. The response of the motor will be compared with the results obtained from the simulation and required changes will be incorporated in the design for the desired motor behavior.

The battery pack will be connected to the motor controller through a series of protective relays and the Battery Management System (BMS). The battery connections to the motor controller would also have a pre-charge circuit to limit the huge inrush current at the time of starting and a discharge circuit to discharge the residual energy in the battery once the vehicle is turned off. The BMS will receive control signals and the operation of the network built so far will be tested for different input signals from the pedals as well as from the vehicle controller.

The next step would be the introduction of engine generator into the power train network. The engine is first coupled to the generator and the speed control system would be developed. The speed control system will allow the vehicle controller to set the engine operating point in the region of maximum fuel efficiency. Also a voltage stabilization unit will be required to keep the generator voltage constant in the event of changes in the engine speed during loading of the generator and hence the engine. The engine generator would then be merged into the power train network, powering the motor controller directly after the incorporation of safety relays in between. Thus the engine generator set is placed in parallel with the battery module.

The ultra-capacitor module would be integrated in the power-train. First a DC/DC converter for the voltage stabilization of the voltage of the ultra-capacitor module would be fabricated taking into account the high value of current that it has to handle and the surges that may appear in the current waveform. The ultra-capacitor with the DC/DC converter is placed in parallel with the battery pack

The Regenerative Braking (RB) system would be based on brake pedal position sensor. The position sensor, depending upon the position of the brake pedal position, will determine the amount of regenerative brake and the ratio of friction brake and the regenerative brake to be applied. The

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pedal should be very robust and should also incorporate a brake over travel switch and brake panic switch which in case of brake failure will shut down the entire power train network and energy supply from any source.

Once the entire power-train has been assembled with necessary protection, the power-train network is then equipped with a master switch, shutdown button and insulation monitoring system.

3.2. Mechanical For all the fabricated components first the CAD model would be made followed by a satisfactory

stress analysis simulation wherever needed. Such components would be chassis, wheel hubs, uprights, suspension rocker, engine intake exhaust, engine-generator coupling, engine-differential coupling, seat, body panels, A-Arms, etc.

Drivetrain: Differential mounting on chassis would ensure that its movement is restricted in all the directions. Sprocket/Pulley would be CNC machined.

Suspension: Wooden jig would be made to fabricate A-Arms. Rocker would be CNC machined. Suspension mounts to be carefully welded with the chassis.

Steering: Male rod ends would be attached with steel tubes of prescribed size to fabricate the tie-rods and steering rods. Upright would be CNC machined.

Wheel Assembly: It would consist of wheel, hub, disc, caliper, upright, bearing. Brake: Aluminum brake pedals to be machined and standard brake over-travel and brake-panic

switches to be installed. Chassis: A wooden jig would be fabricated for the chassis fabrication. It will have special holding

points for the steel tubes such that all the tubes can be held at relative positions touching each other and later the joints can be easily TIG/MIG welded. Then mounting and brackets would be welded followed by the triangulation members.

Body and Seat: A mold would be made up of wood and Plaster of Paris, on which different layers of body panel material and epoxy resin would be placed. The final coat would be carefully done to obtain best finish.

3.3. Overall Assembly Once the mechanical and electrical systems are successfully fabricated, the two have to be integrated as a single system to complete the fabrication process. During the integration process following points needs to be taken care of: The components of the electrical power-train have to be placed in the frame such that mechanical

forces are balanced on all sides for the overall stability of the vehicle. Also the high voltage and the low voltage circuits should be physically separated with a certain minimum distance between the two.

The metallic frame also has to properly insulate from the high voltage electrical system for the safety of the driver.

The electrical components should be properly shielded so as to prevent activation of the shutdown system by rainfall on the car.

All the sharp edges should be made blunt.

4. Testing and Debugging Testing of the fabricated vehicle would be very critical as it has to ensure the validity of design. Every fabricated/assembled system would undergo testing as soon as it is ready. All the electrical systems would undergo lab testing prior to their assembly. After the assembly, the entire car will be tested as a whole and any problems encountered will be debugged. The testing phase will incorporate the following important verification: Proper functioning of the vehicle control system ensuring the proper switching from one mode to

the other. Dynamic testing of the vehicle for specified performance of acceleration, top speed, stability,

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control and vehicle range in pure electric as well as hybrid mode. Testing for proper functioning of the shut-down systems in case of failure. Testing of the amount of energy that is recovered during the regenerative braking. Brake panic and over-travel switch test. Insulation system test. Insulation Measurement Test: The insulation resistance between the tractive system and control

system ground will be measured. To pass the IMT the measured insulation resistance has to be at least 500 Ohm/Volt related to the maximum nominal tractive system operation voltage.

Rain Certification: To become Rain Certified, a vehicle must first pass the Insulation Monitoring Test described above. After this, it must survive a 120 second water spray with all systems energized and must then stand for a further 120 seconds without tripping the IMD. The water spray will be directed from the top, front and sides of the vehicle. The spray is intended to simulate rain and will typically have drops ranging in size between 0.1 to 5 mm in diameter.

Acceleration Test: The acceleration course length will be 75 m from starting line to finish line. The course will be at least 4.9 m wide as measured between the inner edges of the bases of the course edge cones. Cones are placed along the course edges at intervals of about 20 feet.

Skid Pad Test: The objective of the skid-pad event is to measure the car’s cornering ability on a flat surface while making a constant-radius turn. The layout would be made as follows: There will be two (2) pairs of concentric circles in a figure of eight pattern. The centers of these circles will be 18.25 m apart. The inner circles will be 15.25 m in diameter, and the outer circles will be 21.25 m in diameter. The driving path will be the 3.0 m wide.between the inner and outer circles.

Brake Test: The brake system will be dynamically tested and must demonstrate the capability of locking all four (4) wheels and stopping the vehicle in a straight line at the end of the acceleration run. The regenerative braking feature must be turned off during the brake test.

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10. Design of the 2013 Car Power train The vehicle implements a series type hybrid power-train which involves a sophisticated arrangement of motors, generator, battery and power electronics to give performance as per the Formula Student competition standards.

11. Specifications of the 2013 car

Dimensions Front Rear Overall Length, Width, Height 2237mm long, 1475mm wide, 1224mm high Wheelbase 1550mm Track Width 1325mm 1250mm Weight with 68kg driver 189 kg 161 kg

Suspension Parameters Front Rear Suspension Type Double unequal length A-Arm.

Push rod actuated spring and damper Double unequal length A-Arm. Push rod actuated spring and

damper Tire Size and Compound Type 20.5 x 7-13 R25B Hoosier 20.5 x 7-13 R25B Hoosier Wheels (width, construction) 6 inch wide, Keizer Mg-Al A1 series 6 inch wide, Keizer Mg-Al A1

series Center of Gravity Design Height 298 mm above the ground Suspension design travel 25mm bump/ 35 mm rebound 28mm bump/ 35 mm rebound Wheel rate (chassis to wheel center) 13 N/mm 19.5 N/mm

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Roll rate (chassis to wheel center) 1.6 degrees per g Sprung mass natural frequency 2.0 Hz 2.6 Hz Jounce Damping 3 N.s/mm 3 N.s/mm Rebound Damping 1.9 N.s/mm 1.9 N.s/mm Motion ratio / type 1.7 / progressive 1.9 / progressive rate Camber coefficient in bump (deg / m) 36.5 deg/m 41 deg/m Camber coefficient in roll (deg / deg) 0.5 deg / deg 0.5 deg / deg Static Toe 0 deg toe, adj. via rod-ends on tie

rods 0 deg toe, adj. via rodends on tie

rods Static camber and adjustment method -1 deg, adj. via inboard rod ends -1.5 deg, adj. via inboard rod ends Front Caster and adjustment method 6.5 degrees non-adjustable - Front Kingpin Axis 1 degrees non-adjustable - Kingpin offset and trail 0 mm offset, 29.5 mm trail - Static Ackermann and adjustment method 97% Ackermann adjustable via rod ends at the upright - end of the tie

rods Anti-dive / Anti Squat 40% 45% Roll centre position static 74 mm above ground 82 mm above ground Roll centre position at 1g lateral acc 71.5 mm above ground, 84 mm

toward unladen side 80.5 mm above ground, 58.5 mm

toward unladen side Steer location, Gear ratio, Steer Arm Length

Front steer, rack displacement 80 mm for 1 turn of pinion. 70mm steer arm

Brake System / Hub & Axle Front Rear

Rotors Outboard Fixed, Stainless steel, hub mounted, 220 mm dia.

Outboard Fixed, Stainless steel, hub mounted, 210 mm dia.

Master Cylinder 0.75" front bore / 1" rear bore Calipers Dual piston, 1.25" dia., fixed Dual piston, 1.25" dia., fixed Hub Bearings Double row angular contact bearings

(80 mm OD and 40 mm ID) Double row angular contact

bearings (100 mm OD and 55 mm ID)

Upright Assembly CNC 6082 T6-Al, integral caliper mount

CNC 6082 T6-Al, integral caliper mount

Axle type, size, and material Rotating axle, 40mm dia, 6082 T6 Aluminum

Rotating axle, 55mm dia, 6082 T6 Aluminum

Ergonomics

Driver Size Adjustments Seat inserts, fixed steering wheel, Pedals fixed Seat (materials, padding) glass fiber lay-up, padded lumber and knee protection, 80mm foam head

support Driver Visibility (angle of side view, mirrors?)

225 degree side visibility, no mirrors

Shift Actuator (type, location) No change of gears and hence no shifter Clutch Actuator (type, location) No actuation of engine clutch Instrumentation LCD display, shut-down switch, master switch, LEDs

Frame Frame Construction Tubular space frame Material 1020 steel round tubing 16mm to 25mm OD Joining method and material TIG welding with MS 1.6mm filler Targets (Torsional Stiffness or other) 1600 N-m / deg Torsional stiffness and validation method 1500 N-m/deg via FEA Bare frame weight with brackets and paint 40 kg

Crush zone material Standard Impact Attenuator Crush zone length 250mm

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Powertrain

Engine Manufacture / Model Bajaj Discover 125 cc Carburetor Engine Engine Bore / Stroke / Cylinders / Displacement

21mm bore / 22mm stroke / 1 cylinder / 124.6 cc

Engine Induction (natural or forced, intercooled)

Natural

Engine Throttle Body / Mechanism Servo motor controlled 24 mm lift valve integrated in carburetor Fuel Type RON 98 Engine Max Power design RPM 8000 Engine Max Torque design RPM 5500 Fuel System (type) carburettor Fuel System Sensors (used in fuel mapping) Throttle Position, Mass control

Intake runner length(s) 150mm runner Exhaust header design Stainless steel tubing, routed through side into muffler Effective Exhaust runner length 500 mm Ignition System Dual spark Oiling System (wet/dry sump, mods) Wet sump Coolant System and Radiator location Air cooled Fuel Tank Location, Type Floor mounted between firewall and engine, steel tank 2 Liters Muffler Single glass pack muffler, 2-3 liter volume Traction motor Brushless PMAC, 3 phase, open frame ME0913 controlled by motor

control Motor power rating 12 kW continuous, 30 kW peak, Motor maximum rpm recommended 5000 rpm Motor peak stall torque 90 Nm Motor current rating Continuous current 125 Amp. AC, Peak current 420 Amp for 1 min Motor cooling Forced Convection, temperature sensor integrated Controller Kelly KH8 opto-isolated PMAC motor controller KHB72701 Operating frequency 16.6 kHz

Controller supply voltage range 10V to 30V Thermal Protection Current cutback warning and shut - down at high temperature

Full power operating temperature -30 C to 90 C Generator Brush type PMDC, open frame ME0709

Generator current rating 300 Amp peak (1 min), 125 Amp cont. Generator Cooling Air cooled

Battery Li-ion, 72 V - 48 Ah Battery cooling Air cooled

Drivetrain Drive Type Steel chain Differential Type Quiafe ATB limited slip, Final Drive Ratio 5 Engine operating gear and rpm 5th gear (topmost), 1800 - 2750 rpm at output shaft

Gear ratio between engine and generator 1.7 Engine Generator coupling Chain coupled Half shaft size and material 30mm OD solid steel hardened Joint type Tripod joints

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12. Project Completion Status

Designing Fabrication Testing March –

April 2012

May –June 2012

July – Aug 2012

Sept – October 2012

Nov – Dec 2012

Jan – Feb 2013

March –April 2013

May –June 2013

12.1. Work done till now The designing work started in March 2012 and major designing was completed by the end of November 2012. Currently project is in the fabrication phase and nearly 80% of fabrication is complete with major assemblies done. Work already accomplished is as follows :

Roll-cage fabrication Welding of mounts Suspension A-arm fabrication Mounting of dampers and steering rack Individual testing of engine, motor, controller, generator Controller – Motor – differential coupling Engine – Generator coupling Brake pedal box fabrication CNC machining of uprights, hubs, rockers and motor mounts Custom intake – exhaust fabrication Mounting of servo actuated throttle control Mounting of engine, motor, generator on the roll cage

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12.2. Work left to be done

Complete mounting of power-train on roll cage Wheel assembly with roll cage Brake system mounting on roll cage Seat, dashboard, safety harness and mounting of other ergonomic components Mounting of cooling fans and ducts Placement of all the electrical HV – LV circuits in waterproof boxes and other insulation. Body fabrication and mounting Final testing and debugging

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References: 1. History of Hybrid Vehicles". HybridCars.com. 2006-03-27. Retrieved 2010-03-21. 2. Matt Lake (2001-11-08). "How it works; A Tale of 2 Engines: How Hybrid Cars Tame

Emissions". The New York Times. Retrieved 2010-03-22. 3. "Hybrids Cost-Efficient Over Long Haul". Business Week. 9 January 2007. 4. “Top 10 Hybrid Myths".Hybridcars.com.2007-04-27. Retrieved 2012-08-20. 5. December 2011 Dashboard: Sales Still Climbing". HybridCARS.com. 2012-01-09. Retrieved

2012-01-10 6. “US intends to spend more on electric vehicle research".Gm-volt.2011-09-28. Retrieved 2012-

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