Milestone 2: Project Proposal E.E Advisor : Dr. Li M.E. Advisor : Dr. Shih Team Members: Tomas Bacci Danny Covyeau Scott Hill Stephen Kempinski George Nimick Sam Risberg

Proposed Design  Overview  Electric Category  Mechanical – braking, chassis, suspension and steering  Electrical – motor design and battery management  Direction  Feasibility, tangibility, and budget  Constraints  Budget, rules

University of Texas, Arlington Nearly every vehicle from

Project Management  ME Systems  ME Leader – George Nimick  Chassis – George Nimick and Sam Risberg  Braking – Sam Risberg  FEA – George Nimick and Tomas Bacci  Steering and Suspension – Stephen Kempinski and Tomas Bacci  EE Systems  EE Leader – Scott Hill  Motor Control and Design – Danny Covyeau  Battery Management and Accumulator Design - Scott Hill

EE Top-Level Diagram

Propulsion/Motor Design

Propulsion  4 electric motors, one on each wheel.  Mounted onboard the vehicle (i.e. not ‘in-wheel’ or ‘hub’ motors)  Each motor will have its own gear reduction so as to limit the top speed of the vehicle as well as increase the mechanical torque.  2 motor controllers, 2 motors per controller  1 controller for two front motors  1 controller for two rear motors  Motors will be wired in a series configuration  2 HV battery packs, 1 per controller  Will help distribute the weight evenly between the front and rear of the vehicle.

Why AWD?  Traction at all four wheels  Cornering Stability  Load Transfer  Deceleration  Regenerative Braking Advantage  Acceleration  AWD biased towards the rear wheels  Formula SAE Dynamic Events  Autocross  Average Speed: 25 – 30 mph  Endurance  Average Speed: 29.8 – 35.4 mph  For more information see:  2_0506_front_rear_allwheel_drive/viewall.html

Electric Drive  The electric motors must work with one another in such a way to safely, efficiently and quickly propel the vehicle.  The motors should all be the same make and model to simplify the design. ItemCostQuantityShippingTotal Motor$ $ $

Electric Motors Robotmarketplace.com Agni 95-R  Permanent Magnet  72 VDC  400 Amp peak  93% Peak Efficiency  30 peak horsepower  Only 24 lbs  6000 rpm max rotational speed

Motor Controllers  The motor controllers should be able to control two motors in series simultaneously  Regenerative Braking built-in  The motor controller selected should be specifically built for the type of motor chosen (i.e. ac induction, series dc, etc).  It should be able to handle at least twice the rated voltage of the motor and the same maximum current of the motor. Cloudelectric.com ItemCostQuantityShippingTotal Controller$ $ 60.00$

Motor Control System  The motor control system will consist of two permanent magnet motor controllers.  One will control the front motors while the other will control the rear motors.  The motors in the front/back will be connected in a series configuration such that a single controller can operate both motors simultaneously.  This will not only simplify the design but will also create somewhat of a differential- like effect for the front and rear.  Separate battery packs  One in the front and one in the rear to help create a better weight balance between the front and rear.  These packs will be wired in parallel with one another to maintain a constant potential difference between the front and rear controllers and so that there is a common ground.

Throttle Control  The throttle should directly affect the vehicles speed and/or torque.  Theory:  Accelerator pedal called a pot box or potentiometer box.  Sends an analog signal to the ECU.  The ECU will then plug this signal, along with signals from each motors RPM sensor, the brake pedal, and other sensors into an algorithm that will determine what analog values to send to both the front and rear motor controllers.  The front and rear controllers will receive different signals depending on the amount of torque desired at either end. Cloudelectric.com

Battery Management/Accumulators

Accumulator  Lithium Polymer Batteries  Voltage Per Cell : 3.7V  Desired Pack Configuration: 3S String with 11.1V per pack  Chosen because desired voltage for each motor controller is 144V and in series it takes almost exactly 13 batteries to achieve this voltage  Due to competition rules (fusing parallel connections) the team cannot easily use packs that are internally wired in parallel. Therefore packs such as 3s2p that would achieve higher than 8Ah per pack cannot be used. Picture Courtesy Danny Covyeau Hobbyking.com

Battery Characteristics  Maximum Capacity : 5,400 Wh  With a voltage of 144V current capacity of 37.5Ah is required to be at the maximum  This is before efficiency is taken into account though so a current capacity of 40Ah will be used.  With a current capacity of 40Ah our vehicle will require a total of 8 parallel strings if 5Ah batteries are used.  If 5.8Ah batteries are used the we could get away with 7 parallel strings, This would save us 13 batteries! Battery Capacity5 Ah5.8Ah Cost Each*~$28.08~$36.97 Total Batteries Needed10491 Total Cost of Batteries~$ ~$ *Prices based off of hobby king Retail website

Battery Discharge Simulation Simulation Schematic 13s8p configuration (actually 39s8p configuration with 3s packs)

Battery DischargeSimulation (Cont). Simulation with a 5Ω Resistive Load Without SOC Measurement Voltage ReadingCurrent Reading Operating Region

Capacitors  Capacitors are being considered for the vehicle in order to take advantage of regenerative braking function included in the controller Danny talked about previously.  According to the Formula Hybrid SAE 2012 Competition Rules “Endurance courses will be configured, where possible, in a manner which maximizes the advantage of regenerative braking.” Picture Courtesy Danny Covyeau

Battery Management System  The teams car used a e-lithion Lithiumate pro BMS.  To our knowledge the BMS is working and will be used in the 2011 car for purposes of budget  More research needs to be done on the on the Cell boards BMS Master Cell Board Elithion.com Picture taken from Car

Battery Charging System  The battery charging system for this years team will need to be much larger than last years since the vehicle is fully electric  The proposed charger is the “Battery Charger HWC4 Series Charger High Output 144V/15A 220VAC Input”  This charger also has a variable charge mode if battery configuration needs to be changed in the case of a large failure in the accumulator system Cloudelectric.com PLCcenter.com

Accumulator Enclosure  A clear polycarbonate insulating material will be used to construct the accumulator enclosure  This material will allow for easy inspection at the competition  This material allows proper insulation of the HV accumulator and the frame of the vehicle TapPlastics.com Newegg.com

Accumulator System Budget ItemQuantityPrice PerShippingTotal Cost Batteries108$28.08~$100$ BMS Master1*$413~$25$428 BMS Cell Board** TBD >$500 Battery Charger1$700~$25$725 Accumulator Enclosure 1$75~$20$95 Total >$4872 *Already Have 1 BMS master from Team (Need 2 total) ** Company Needs to be contacted for pricing

Timeline Pick & Order Batteries Finish Research on BMS & Order Polycarbonate Abuse Test & Design Accumulator Enclosure Create Accumula tor Enclosure Create Battery Packaging & Wiring Test Battery Charging System as a whole Test System as a Whole Nov 1 Dec 1 Jan 1 Feb 1 Mar 1

ME Top-Level Diagram

Chassis

Constructing the chassis  Strong Enclosure and component platform  The chassis will house the driver and a strong enclosure is required to ensure safety  The chassis will not only need to be aerodynamics, but should have a ideal weight distribution and center of gravity  Perform FEA

Chassis Ergonomics  Mounting for:  Brakes  Suspension  Motors  Driver accommodations  Safety equipment mounting  Steering  Body panels  Batteries

Chassis Budget Part Name: CostQuantityShippingTotal Sheet metal (Al) $ $ $ Structural tubing $ $ $ Conduit $ $ $ Honeycomb (Al) $ $ $ Total:$

Chassis Timeline Research Materials and Feasibility – Oct. 15 Preliminary Chassis Design – Oct. 31 Review Rules, Ergonomics and Fitment – Nov. 15 Conduct FEA – Nov 30 Finalize Model – Dec. 15 Build Chassis – Feb. 15 Testing and Review Rules – March 31

Steering speedwaymotors.com

Steering  Goal  Control direction  Selection  Mechanical (Rules)  Less than 7 degrees of free play  Choices: rack and pinion, recirculating ball, worm and sector, articulated steering and four wheel steering  Constraints  Effectiveness  Practicality  Cost  Choice: Rack and Pinion  Installation  Non-binding  Driver operation  Steering shaft

Steering Timeline Major Design of Chassis and Suspension – Nov.15 Research and Selection – Nov 30 Preliminary Design – Dec.15 Solid Model and Fitment – Jan 15 Source Parts – Jan. 22 Install and Test – Feb. 29

Estimated Budget for Steering ItemCostQty.ShippingTotal Steering Wheel$ $15.00$ Steering Quick Release$ $4.00$ Rack and Pinion$96.951$8.00$ U-Joints$28.002$5.00$61.00 Rod Ends$12.144$8.00$56.56 Tubing$27.831$8.00$35.83 Hex Stock$17.951$2.00$19.95 Total:$619.30

Braking

Braking system  Single control to ensure safe stop on four wheels  -We will have one pedal acting on four wheels  -A master cylinder will multiply the pedal force into a hydraulic force  Two independent hydraulic circuits  One circuit will control the rear wheel braking the other the front  This will ensure if one circuit fail another will be in place  Safety will be the main concern for this system

Braking Continued  Brake line Durability  We won’t be using a factory rubber brake line  Stainless Steel braided line will prove more durable for racing situations and heat produced from the extreme conditions  Testing the brakes  To test the systems we will apply maximum pressure to the brake pedal at a high speed and ensure all four wheels lock up as stated in the FSAE Hybrid rules.

Braking System Budget Part Name: CostQuantityShippingTotal Brake Lines (Steel Braided) $ $ 5.00 $ Brake Fluid $ $ - $ Brake Caliper $ $ $ Brake Rotor and pads $ $ $ Total:$

Braking timeline Research and Selection – Oct. 31 Measure dimensions and needed lengths – Nov. 15 Design brake components in SolidWorks – Nov. 31 Mock parts to chassis and check clearance with suspension – Dec. 8 Source Parts – Dec. 15 Install and Test for 4 wheel lock up – March 31

Suspension

Competition Constraints  Suspension  fully operational suspension system with shock absorbers, front and rear  usable wheel travel of at least 50.8 mm (2 inches), 25.4 mm (1 inch) jounce and 25.4 mm (1 inch) rebound, with driver seated.  Ground Clearance  with the driver aboard there must be a minimum of 25.4 mm (1 inch) of static ground clearance under the complete car at all times.

Competition Constraints Continued…  Wheels and Tires  Wheels  The wheels of the car must be mm (8.0 inches) or more in diameter.  Tires  Vehicles may have two types of tires as follows:  Dry Tires – The tires on the vehicle when it is presented for technical inspection are defined as its “Dry Tires”. The dry tires may be any size or type. They may be slicks or treaded.  Rain Tires – Rain tires may be any size or type of treaded or grooved tire provided:

Understanding Vehicle Dynamics  Weight transfer – actual movement of the vehicle CoM relative to the wheel axes due to displacement of the chassis as the suspension complies.  Downforce - downwards thrust created by the aerodynamic characteristics of a car.  Roll center - the notional point at which the cornering forces in the suspension are reacted to the vehicle chassis/body.  Camber – angle of the wheel relative to vertical.  Caster – angle to which the steering pivot axis is tilted forward or rearward from vertical  Toe – angle that each wheel makes with the longitudinal axis of the vehicle  Pitch - front and rear of the chassis go in opposite directions.  Yaw - rotation of the car in a horizontal plane around a vertical axis.  Heave - movement of the diagonally opposed wheels in opposite directions

Set up accuracy  Dependent on:  Springs  Shocks  Camber  Caster  Toe  Tire pressure  Ride height  Wings

Independent Suspension  Better ride quality  Improved handling  fully adjustable

SLA Double Wishbone  Short Long Arm Suspension  Lower A-Arm is longer than the Upper A-Arm  Reduced changes in camber angles  Reduces tire wear  Increases contact patch for improved traction

Connection to Sprung Mass  Predetermined geometry points  Chassis may be modified to accommodate  Mounting brackets welded to chassis

Connection to un-sprung mass  Spindle design  Regenerative Brake assembly  Steering connection  Wheel hub and bearing  Wheels/Tires

Connection to un-sprung mass Continued

Push rod, spring, damper  A push rod will transfer suspension forces to coil-overs mounted to the chassis -Reduces amount of un-sprung weight as the springs and shocks move in-board -Spring compression rate can be controlled with a bell crank -Increased aerodynamics for open wheel application

 Linkage will be set up so as wheel travel increases, the rod will come closer to a 90 degree angle with the shock absorbers, increasing the efficiency of the shocks - Suspension stiffens with wheel travel  A bell crank can allow you to place shocks horizontally if needed Push rod, spring, damper Continued

Test Plan  Observe  Measure  Analyze  Simulation  Predict changes  Improve performance

Suspension - Budget Partcostquantityshippingtotal Aluminum Block $ $ Rod ends$ $ springs$45410$190 shocks$675420$2720 Wheel Hub Aluminum Block $ $ steel tubing $ Total$

Suspension-time line ObjectiveCompletion Date ResearchIn Progress Preliminary DesignNovember 14, 2011 ModelNovember 30, 2011 Determining final geometryDecember 7, 2011 Connection to sprung massDecember 14,2011 Wheel Hub/spindle designDecember 20, 2011 CAD compileJanuary 15th 2011 Final Product BuildMarch 15st 2012

Risk Assessment  Risks associated with our design include:  Individual Component Failure  Unresolved Options in Design  Sick Team Member(s)  2012 Formula Hybrid Rules Document Non-compliance  Budget Miscalculation

Important Project Deadlines Senior Design  Milestone 3: Conceptual Design Review 11/14/11 Competition  Registration Deadline (completed) 10/04/11  Competition forms  Structural Equivalency Form 01/30/12  Impact Attenuator Data 02/27/12  Design Report & Spec Sheet s 04/09/12 The 2012 Formula Hybrid Competition begins April 30 th Date due

EE Budget Proposal

ME Budget Proposal Part Name: CostQuantityShippingTotal Penske Shocks $ $ $ 2, Suspension springs $ $ $ Hoosier Tires (Dry) $ $ $ 1, Hoosier Tires (Wet) $ $ $ 1, Rims $ $ $ 1, Rod Ends $ $ 8.00 $ Brake Lines (Steel Braided) $ $ 5.00 $ Brake Fluid $ $ - $ Brake Caliper $ $ $ Brake Rotor and pads $ $ $ Wheel Hubs $ $ $ Rack and pinion $ $ 8.00 $ Steering wheel $ $ $ Steering wheel quick release $ $ 4.00 $ Block of Aluminum $ $ $ Sheet metal (Al) $ $ $ CV Axle $ $ $ Sheet metal seat $ $ $ Total:$10,291.83

Joint Budget Proposal **The Total Direct Costs is the actual cost of the project since expenses such as personnel and fringe benefit costs are not actually being paid.

References   _31_06.pdf _31_06.pdf          