Status Report
Contents
1. 27 2010 F2 7 Final System Testing 3 28 2010 4 10 2010 D2 1 Draft User s Manual 3 29 2010 4 26 2010 D2 2 Final Report and Presentation 4 9 2010 4 26 2010 02 1 Design Documentation 2 21 2010 4 29 2010 02 2 Project Management 2 21 2010 4 29 2010 Analysis of Schedule Because of delays caused by parts selection namely the relays the learning curve for using the CNC milling machine and delays in receiving the necessary tooling parts to make the cuts bevels drills etc that must be made to produce the Faraday apparatus the project is behind the intended schedule in most aspects of the construction April s work on the crankshaft drive chain connector rod and power supply mount however is well ahead of schedule allowing her to assist Kun in whatever way necessary particularly in the construction of the power supply case This should be an issue that prevents us from completing the project however Many of the items listed on the Gantt chart written in December were assigned a longer duration than will be required to see them to completion giving us time to catch up as soon spring break provided that work is steady At this point our greatest concern is completing the Faraday apparatus and testing it to see that it s working properly If not priority on all members will shift to making the proper adjustments to the apparatus to produce an EMF capable of charging the lead acid battery Plan to Proceed All major electrical compone2. 50 pedal rpm for a total of 25 hours and record the new measurements which will then be compared quantitatively All measured values should be within 10 of the original values Ease of ride testing In order to verify the comparative ease of riding the bicycle with existing industry standards the oxygen consumption for a batch of three students will be measured while riding for 2 5 3 hours at an average of 50 RPM and aiming for an oxygen consumption of 1 1 5 L min Mechanical Progress Crankshaft Components and Power Supply Mount The design for each of the crankshaft parts has been modified slightly from the last design report Many of these changes were made for convenience purposes Others were to provide extra strength and stability or clearance The major parts included here are the power supply mount flywheel and the connecting rod between the flywheel and piston All of these parts have already been completed except for the final painting and polishing which will be done after the initial tests are completed Also included in the crankshaft mechanism is a normal bike chain which was bought at a sporting goods store and has been shortened for use in this project Currently under consideration is a chain guard which can be easily made by heating up a polycarbonate sheet and shaping it so that it curls around the exposed chain t4 Figure 3 1 Power Supply Mount with attached flywheel Rear view Power Supply Mount The power suppl
3. DC DC converter as well as ceramic capacitors can R2 and R3 are voltage dividing resistors which set the output voltage level based on the input to the system and thus may not be determined until the potential which may be generated by the Faraday apparatus is known D2 is a standard PN junction diode but D1 is a Schottky diode which must be rated for at least 40 V R1 which has been ordered as a free sample is the current sensing resistor and is determined by the following equation s Jh V R _ 1391 Ves is typically set to be about 100 mV and lourimax was determined to be about 8 A for the Faraday apparatus in calculations made in the fall Plugging those numbers in yields a resistance of 9 6 mQ 10 mQ The current sensor was located on an online vendor site for KOA Speer Electronics and five samples were ordered just to be safe The P channel MOSFET acts as an external switch for the DC DC converter allowing it to create a high frequency PWM with a duty cycle set by the voltage divider on the feedback pin Its qualifications as set by the data sheet were a low gate charge lt 80 nC and drain to source resistance comparable to the current sensing resistor Finally the 100 WH inductor was selected on the basis of a very low coil resistance 37 mQ and a high DC current rating 7 A These qualifications were best met by a toroidal inductor found on Jameco so that part was selected for the design Lin
4. Pin 8 Ground ZAUAN XI RI To Battery 300kO RELAY_NO Figure 3 20 Overcharge Protection Multisim Representation z3 l For this circuit when the voltage across the battery is below 13 V the logical output of the MAX8211 is essentially low forward biasing the PNP transistor and allowing current flow from the generator to the relay and logic inverter The logic inverter pulls that signal low and the LED indicator stays off The relay is energized closing the switch and allowing the battery to charge If the voltage across the battery is greater than or equal to 13 V the output of the MAX8211 is essentially high and no current flows from the emitter to the collector of the PNP Thus the logic inverter input is pulled to ground across the 300 kQ resistor and the LED receives a high signal turning it on The relay is not energized such that the switch is open and no current flows from the generator to the battery Note that ground and supply for the inverter are not drawn but are included in the PCB layout R3C 13kQ yl R2 UI Luvi Seo ia 11 8 V a a RIA 4 5 JIA lt 100k MAX8211 Key A RIB 220k0 RIC susa Pin 1 NC1 ue Ql Pin 2 Hysteresis Pin 3 Threshold Pin 4 Output BJT_PNP_VIRTUAL Pin 5 VIN U3A Pin 6 NC6 Pin 7 NC7 Pin 8 Ground ZADAN XI T RI o Load s 300kQ i RELAY_NO e Figure 3 21 Discharge Cutoff Multisim Re
5. 5 20 beam dispersion able to illuminate a distance in front of the rider up to at least 30 meters with maximum intensity of at least 20 candela Headlight will run continuously with constant luminosity beam dispersion etc as long as the power supply discharge switch is in the on position and the charge level in the supply is above the cutoff threshold Will be able to support two low power electrical loads up to 100 W each for two hours Generator able to generate 125 150 watts Energy storage unit maximum capacity of at least 400 watt hours Waterproof power supply casing Automatic cutoff when the charge drops below 5 of its maximum capacity Supply testing The energy storage unit will be tested over 20 complete charge discharge cycles at a supply rate of no less than 40 W hr to confirm that the system performs as well as originally specified The cutoff system must be shown to occur within a 20 tolerance of the 5 charge level cutoff threshold gg PR Peripheral testing Through night time testing it must be demonstrated that the headlight is capable of meeting all of the above listed physical qualities Mechanical testing Due to the addition of external parts on the bike testing will need to be done to ensure that the structural integrity of the bicycle is not compromised We will measure and record the initial tire pressure tread height bolt tightness etc of the bike We will then ride it at a steady rate of 40
6. Requirements Specification Overview Our project team will design and build a portable generator powered by the rotary action of a bicycle wheel capable of generating environmentally clean energy which may be used for supplying low power applications up to 100 W The energy storage unit may either be simply charged exclusively while pedaling or some of the power may be routed to an attached headlight lowering the charge rate on the energy storage unit by a small amount not more than 20 W Once charged the energy storage unit may be detached and later used as a standalone power supply Problem Statement In a world where more people in our society are exhibiting environmental conscientiousness bicycles are rapidly becoming the most economically and ecologically viable alternative transportation method This can be attributed to the bicycle s lack of emissions and gasoline expenses Consumers who have already acknowledged the benefits of this form of transportation would undoubtedly be attracted to a way to increase the bicycle s positive environmental impact even more Through P E E V S we aim to reach out to these potential consumers By designing a portable energy storage unit which uses the bicycle as a renewable mechanical source of energy in order to supply low power loads cell phones laptops etc we will add yet another benefit to the list of the bicycle s environmental contributions Operation Operation of the devi
7. and then wired in a full wave rectifier configuration and tested with a 60 Hz 20 VAC input signal to ensure proper rectification Full wave rectification occurred as expected with a voltage drop of 1 6 V across any path taken through the rectifier Capacitors The twelve high voltage 330 uF capacitors were individually tested to verify charge and discharge characteristics then wired to the rectifier circuit with a 1 kQ load to test that the rectified signal may filtered to a consistent DC level The schematic of the test circuit is shown below After some iteration it was determined that eight of the capacitors should be placed in parallel after the rectifier to achieve the appropriate amount of filtering within 10 tolerance of the baseline voltage The other four capacitors are being placed before and after the SLA in order to level out any signal perturbations which may manifest themselves D1 D3 D4 vi 20 Vrms D2 re hai la la la la la la RI 3304F 330pF uF 330pF 3304F il Figure 3 19 Rectifier and Capacitor Test Circuit Multisim Schematic Lead Acid Battery The SLA was first charged to maximum capacity using a lead acid battery charger at 2 A Maximum capacity was found to be 13 0 V when measured while disconnected ee from the charger The battery was then discharged across a resistive a load to 12 V and charged back up again this time at 8A No noticeable temperature increase of the ba
8. ble to successfully power both my laptop and cell phone again The DC DC converter has not yet been tested because its package is a 10L MAX which can t be breadboarded in a prototyping board Design Considerations Relay Selection One of the critical design components which we were never able to locate in the fall is an electronic relay which could be used in the cutoff systems Finally we located a solid state relay denoted KG1010D which met all the performance specifications needed for our system At 24 95 a unit it would have been nice to find something cheaper but nothing else has turned up which might serve as less expensive substitute and such a cost is within our budget limitations The data sheet is included in the Appendices section Because the original design for the cutoff systems used energize to break type relays the design for the cutoff systems had to be altered to accommodate the KG1010D which is a energize to make type The alterations to the design including the new resistance values determined through experimentation with the MAX8211 voltage detector and changes in transistors are shown following 14kQ peee R2 VI vi 2 2MO igs 129V sa a BT RIA Hi 5 Key A 100kQ MAX8211 RIB gos RIC 15KQ u2 Pin 1 NC1 Ql Pin 2 Hysteresis Pin 3 Threshold Pin 4 Output BJT_PNP_VIRTUAL Pin 5 VIN U3A Pin 6 NC6 Pin 7 NC7
9. ce will be simplistic and intuitive such that the bicycle is not any more difficult or unwieldy to ride based on O consumption than any other conventional bicycle While in use the movement of the bicycle s wheel automatically stores energy to the unit through a generator The user may flip a switch attached to the handlebars if he she wishes to instead power a mounted headlight Once charged the user may detach the energy storage unit from its housing on the bicycle which may then be used to power other electrical loads once an on off switch allowing electrical discharge has been flipped to the on position The user will be notified once the supply has been depleted of energy and has cut off discharge so that the user may then reattach it to the bicycle in order to charge it again Deliverables e Mobile bicycle with gear shifting capabilities and power supply mount e Detachable energy storage unit with LED indicators e Generator e LED headlight with on off switch e User s manual e Circuit diagrams schematics including analysis and simulations e CAD drawings and analysis e Final report including test results list of materials and final design Draft User s Manual Setup Operation Maintenance Flip power supply discharge switch to the off position Mount power supply Fasten and tighten housing clamps Plugin LED headlight ensure headlight switch is in the off position Connect energy s
10. curely fastened to the piston using this glue ee WC SOKN Max Load Figure 3 15 Instron with glue testing bar Testing bar Load vs displacement Me 2 mo e par 0 02 0 04 0 06 0 08 0 1 0 12 Extension in Figure 3 16 Friction Testing The frictional force between aluminum cylinder and piston is an important measurement in our project The lower the friction force the higher the overall efficiency of the generator Because of this we devised a method to test the amount of friction present between the piston and the casing shown in Figure 3 14 and Figure 3 15 In Figure 3 15 the distance L between the weight and the ground is 11 5 29 2cm The mass of the weight is 0 155kg The diameter of the pulley is 0 75 1 9cm The mass of the pulley is 0 012kg The mass of the piston and magnet is 0 175kg With these properties the constant friction force can be calculated if the falling time of the weight is measured a fsp Cylinder Pulley Piston Figure 3 17 Frictional Force Experiment Figure 3 18 Frictional Force Experiment 7 Jh We will set up these devices to measure the friction force between the piston and cylinder Before testing there are several things that need to be measured the mass of the weight the mass of the piston the height of the weight Furthermore we also need to calculate Moment of inertia of the pulley The only thing need to be measured duri
11. ear Regulators Although too inefficient to be applied in regulating the power signal two points in the electrical system will still require a 5 V supply the headlight and the logic inverter To this end two 5 V linear regulators rated at up to 2 2 A were purchased in order to ensure that those needs are met PCB Design After completing the changes to the overcharge protection and discharge cutoff systems and determining the appropriate values and arrangements of the peripheral components for the DC DC converter the PCB was ready to be designed The layout was done using PCB Artist the software required by 4PCB which is the company we plan to hire to print off the circuit board for us The figure is shown below although not to scale Actual circuit dimensions will be 4 x 6 101 6 mm x 152 4 mm Already purchased Item Bicycle Headlight Headlight Replacement Copper wire Magnets LEDs Phenolic Aluminum Plastic Solid State Relays Pencil Sharpener mock up Power Inverter Lead Acid Battery 12 x 330 pF Capacitors 4 x Rectifier Diodes Chain Bearings 22 Tooth Gear 34 AWG Magnet Wire 2 x Voltage Detectors 2 x DC DC Convertors DC DC Converter Components Glue Total Spent To be purchased Item Circuit Board Power Supply Case Materials Contingencies Total Remaining Updated Budget Vendor Wal Mart B2Cshop24 com B2Cshop24 com Smallparts com Bunting Magnetics jameco com jameco co
12. lue Because we cannot directly measure how much force is needed to pull the piston and magnet apart we use two congruently cut segments of aluminum bar in lieu of the piston and magnet Using different types of adhesive glue to fix these two parts we will then use an Instron machine to measure how much force is needed to separate the connecting bar Figures 3 13 and 3 14 show the two pieces of aluminum used in the simulation This test is very important to our project because when the piston is moving the magnet may vibrate strongly and if the magnet is not fixed well the magnet probably comes out from the piston So testing glue can help us make sure that the magnet will come out of the piston or not while the piston is moving Figure 3 13 Glue Testing Separate Halves Figure 3 14 Glue Testing Combined Halves f u _ An Instron machine can be used to measure the force that pulls the aluminum bar away The testing bar was already glued for two days with epoxy glue Figure 3 15 shows how the aluminum testing bar was set up in the Instron machine before testing In figure 3 16 the load is increasing while the displacement rises The maximum load in the testing bar is 3694 bf 16 432 kN This indicates to us that the glue tested has more than enough tensile strength to fix the magnet to the piston In our project none of the forces present will ever come close to exceeding 16 432 kN The conclusion is that the magnet will se
13. m Staples Wal Mart BMF Batteries Pololu Robotics Allied Electronics Sport s Basement Grainger Sport s Basement Powerwerx Maxim Maxim Jameco com Lowe s Possible Vendor 4pcb com Lowe s e Cost 214 92 7 34 7 34 26 59 40 60 8 08 56 00 49 90 10 79 19 59 152 04 11 15 9 68 8 74 25 96 7 65 13 21 0 00 Samples 0 00 Samples 20 20 10 00 733 42 Cost 35 00 30 00 51 58 116 58 Analysis of Budget As of now all major components have been purchased with the exception of the PCB board and the materials necessary to manufacture the power supply case After it has been purchased approximately 50 will remain for contingency Because the manufacturing of the mechanical components is nearing completion and as much testing of mechanical components must wait until the PCB board arrives from 4PCB most of that contingency will most likely be spent on electrical components Should we need to order another PCB we will time permitting have the funds necessary to make the appropriate changes and order another one Updated Schedule Task ID Task Description Start Finish 21 Feb 28 Feb 7 Mar 14 Mar 21 Mar 28 Mar 4 Apr 11 Apr 18 Apr 25 Apr F2 3 raday Apparatus Mounting and Testi 2 28 2010 3 13 2010 F2 4 Mechanical Component Attachment 2 28 2010 3 13 2010 F2 5 Power Supple Case Construction 3 7 2010 3 13 2010 F2 6 Integration of Electrical Systems 3 14 2010 3
14. ng the experiment is the time when the weight hit the ground Equation to calculate the moment of inertia oe 2 Where is the mass of the pulley r is the radius of the pulley Free body diagram 1 For piston e Fi oa Ts 2 For pulley Ts 3 For weight Tw Tw 4 For acceleration Weight W Substituting these four equations we arrive at the final equation describing the friction present _ _ Where is the moment of inertia ig PR is the acceleration of weight is the radius of the pulley is the mass of the weight is the mass of the piston is the weight tis the duration of weight falling Results We did this experiment twenty times and the average falling time is 0 38 seconds Using the equations shown above the constant friction force is shown to be 1 02 N which is truly negligible The low friction force means the coefficient of friction force between aluminum and phenolic is very small With such a low amount of friction present the efficiency of the bicycle will surely benefit Electrical Progress Components Testing The first step in beginning the construction of the electrical system as shown in the final design report s Gantt schedule was testing components received for condition and correct functionality Listed are the components whose testing has been completed Rectifier Diodes The four rectifier diodes were each tested with a straight DC input to verify the voltage drop across each
15. nts have been received with the exception of the LEDs and the KG1010D relays which have been ordered The next steps on the electrical side of the project as reflected in the updated schedule are the design of the PCB board the ordering of the PCB board and the wiring and testing of the cutoff systems As that s occurring testing will begin on the Faraday apparatus as Kun finishes manufacturing it By spring break the objective is to have all electrical components assembled tested and working as expected to allow charge from the Faraday apparatus and discharge to the inverter Mechanically April will continue assembly attachment and testing of the crankshaft and drive chain components as well as testing the mechanical joining of the crankshaft and Faraday apparatus April will also help Kun complete his assignments as needed Kun will finish completion of the Faraday apparatus once the necessary tooling parts for the CNC mill have arrived and begin testing with Ben while also working with Ben on the power supply case Appendices
16. olted directly to an aluminum disc that is smaller than the chain ring itself to provide clearance for the chain This is done to provide extra stability and strength for the chain ring This assembly is then bolted to the larger disc with spacers for clearance between the chain and the large disc The 7 5in 19 05 cm disc has been machined so that a ball bearing has been press fit into the center and a countersunk hole has been drilled 3in 7 62 cm from the center This hole is where the connecting rod attaches to the flywheel Figure 3 4 Flywheel Top View Figure 3 5 Flywheel Bottom View ae Connecting Rod Though our last report stated that the connecting rod would be made of steel because aluminum bar was more readily available and less expensive than steel it was a better choice The aluminum bar used is 1 5in 3 81 cm wide 0 25in 0 635 cm thick To fashion the bend in the bar which is necessary to minimize the torque on the connection to the piston the aluminum had to be annealed and precisely shaped A hole was bored in each end of the bar so that two small flanged bearings could be press fit into it The bearings should allow for smooth motion of the crankshaft Figure 3 6 Connecting Rod Side View Figure 3 7 Connecting Rod Top View o Jh Faraday Apparatus Construction Aluminum cylinder As per our design from last semester we are planning to use aluminum to build a cylinder around the ou
17. presentation When the voltage across the battery is above 11 8 V the logical output of the MAX8211 is essentially high such that no current may flow from the collector to the emitter of the PNP transistor The LED is off and the input of the inverter is pulled low through the 300 kQ resistor The inverter then energizes the relay closing the switch and allowing current flow from the battery to the electrical load However if the battery voltage drops below 11 8 V the logical output of the MAX8211 switches to low forward biasing the NPN transistor turning on the LED and de energizing the relay The switch opens and no current flows from the battery to the load preventing the battery from undersupplying the load for jJ DC DC Converter Although testing for the DC DC converter will not be possible until it is attached to the PCB design of the various peripheral circuitry for the MAX1745 still had to be conducted based on the specifications set forth in Maxim s data sheet Generator Supply Pin 1 Ground Pin 2 VL Pin 3 REF Pin 4 Feedback Pin 5 OUT Pin 6 IN Pin 7 EXT Pin 8 VH Pin 9 Shutdown Battery Pin 10 Current Sensor DC DC Converter Multisim Schematic The capacitances for C1 C2 and C3 are predefined in the product data sheet with the stipulation that the capacitors used not be aluminum electrolytics a construction which is not capable of handling the high frequencies generated by the
18. the piston with 25 4 mm deep and 22 2 mm wide first as shown in Figure 3 10 and then to put the magnet into the hole and fix it there with glue At the other side of the piston a hole which connects to the flywheel with connecting rod will be drilled to allow the piston to move Furthermore when all the components are mounted and tested we will reduce the diameter at the center of the piston to reduce the frictional force experienced and then measure and evaluate the new total friction Before the final friction test we will measure the friction present at the normal diameter which is 25 4 mm diameter along the piston Figure 3 10 Modified Phenolic Piston Figure 3 11 is an example which shows how the Faraday apparatus mounts on the bicycle We will use a plastic outside cylinder casing to cover the Faraday apparatus and protect it from environmental factors and the casing will be fixed to the steel mount made by April Figure 3 11 Modified Faraday apparatus Glue Testing Now that we have changed the way the magnet is fixed to the cylinder glue is an important part of our project as the magnet and piston are connected with glue As such it is necessary to measure how strong the glue connecting our components is by measuring the amount of force necessary to pull the components apart Magnet Figure 3 12 Piston With Magnet lt Figure 3 12 is a shot showing that the magnet is completely fixed in the piston with strong g
19. torage unit to generator system Ride bicycle in order to charge power supply For night riding user should flip both the power supply switch and the headlight switch to the on position to power the headlight Once the power supply has been fully charged as indicated by an LED on the power supply the supply may be detached after ensuring that both switches are in the off position At this point one or two low power loads not to exceed 100W may be plugged into the energy storage unit Charging of the low power device will begin once the user has flipped the discharge switch to the on position The energy storage unit will no longer discharge once the voltage level drops to a predetermined threshold as indicated by a low power LED Repeat setup instructions for further use Store bicycle in a dry location protected from the weather 77 PR User Interface Ensure that the discharge switch is set to the off position when not in use Normal bicycle maintenance applies chain tension and lubrication tire pressure etc On Off switch for headlight On Off switch for energy storage unit LEDs indicating maximum charge and low power Physical Capabilities System Testing Easily rideable such that the supply may be fully charged in 2 5 3 hours of pedaling at a rate of approximately 50 rpm with the rider s oxygen consumption ranging from 1 1 5 L min 12 14 W headlight operated by an On Off switch with a 1
20. tside surface of which are copper wires and within which the piston moves There is an easy way to modify our material which is to reduce the diameter of the central part by drilling a hole through the center of the cylinder In our engineering lab we already have the drilling machine necessary to modify our materials After two weeks of engineering lab machines training it is easy to reduce the diameter of the aluminum cylinder and cut the length of the cylinder to 6 15 24 cm When we received adjustable tools the aluminum cylinder was completed finished two weeks ago Figure 3 8 and 3 9 show the cylinder in different views Figure 3 8 Aluminum Cylinder Top View Figure 3 9 Aluminum Cylinder Side View Figure 3 9 shows the completed aluminum cylinder The length of the cylinder is 165 mm and the diameter of the hole is 25 4 mm The shortest distance from magnet to the coil windings which is the thickness of the aluminum cylinder is 0 1875 0 476cm Phenolic Piston For the piston part we initially decided that the magnet would be fixed to the phenolic piston with the connecting rod With this connection the magnet would be strongly held to the piston However because we don t know how hard the magnet is we were afraid that the magnet would crush while being cut Due to budget concerns we did not use our only magnet to test so we switched to another way involving glue The process here is to first drill a hole in
21. ttery or any difficulties in charging were detected at that current Headlight tested the headlight quickly with 4 AAA batteries to test functionality and the headlight functioned correctly then took off the headlight s protective case found the positive and negative terminals and successfully powered the headlight by wiring those terminals up to an adjustable power supply set at 6 V MAX8211 breadboarded both MAX8211 chips to test functionality and adjusted resistances to account for tolerances in the resistors and the experimental internal reference voltages of the ICs After realizing that the output pin of the MAX8211 sinks current instead of supplying it successfully measured logical output transitions at the correct thresholds for both the overcharge protection and discharge cutoff systems The transistors used for the cutoff systems had to be switched from NPN to PNP junctions for the discharge cutoff and vice versa for the overcharge protection after learning that the output pin did in fact sink current Power Inverter successfully tested the power inverter in the car to make sure that it would correctly power a load using my laptop and my cell phone charger then took the inverter case apart to find the positive and negative terminals cut and stripped its power cord and spliced lab wires on in order to hook the inverter up to the positive and negative terminals of the lead acid battery Using that setup was a
22. y mount was shown in the last design report as being made of aluminum and having two identical side supports and several narrow support slats These things have all been changed during the construction of the power supply mount For convenience some mild steel scraps were used instead of the aluminum specified in our last report Instead of having three or four narrow support slats on the platform two wider ones were welded to the frame The left side support differs from the right side by being made out of two thin steel bars in a triangular shape with the platform The right side was made as specified in the last design report going straight up with a bend inward to allow for clearance A slotted hole in the right side support allows for adjustability in the tension of the chain by the lowering a A or raising of the flywheel One thing that was not previously specified was how the power supply mount would be attached to the seat post It has since been decided that a simple plumbing clamp can be bolted to the rack and tightened around the seat post The rack has been made so that it can be adjusted to fit perfectly onto the bike Figure 3 2 Power Supply Mount Right side view Figure 3 3 Power Supply Mount Top view Flywheel The flywheel consists of a 22 tooth chain ring bolted to a 7 5in 19 05 cm aluminum disc The last design report did not specify exactly how the assembly would come together The gg chain ring is b
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