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Final Design Report

1. pue 1055820140101 12 18 W1 2 9g 01 28 H3TIOHLINOO 39OHVHO Joyoedey 3 006 2 AUL LAT 0 ZHL SULIA y AOI y 75390 Figure 14 charge controller circuit diagram 21 DC DC Converter As afore stated the Maxim MAX15046 is a 40V high performance synchronous Buck controller is the switching regulator chosen as a part of the charge controller design This chip while it is complex provided the exact regulation needed all for less than five dollars per IC This IC accepts an input voltage from 4 5V to 40V and outputs a fixed voltage that can be configured between the range of 6V to 8596 of It also provides up to a 25A output capability This will allow stable voltage to be provided to the battery The MAX15046 is excellent for the specifications it needs to meet for the project however it requires a lot of external circuitry and can t be modeled easily is MultiSim The MAX15046 is a pulse width modulated controller which uses a frequency to step down the voltage from the input Despite not being able to be easily simulated the MAX15046 comes with exact specifications how to calculate the values of the external components Beginning on Appendix A7 the equations for the external components can be found These equations are given to find the effective input voltage range set the output voltage set the switch
2. Cvcc 4 7 RRT 49 9kQ TA TJ 40 C to 125 C unless otherwise noted Typical values are at TA 25 Note 2 gt PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS gt VCOMP RAMP Minimum Voltage 200 mV mh COMP Source Sink Current ICOMP VCOMP 1 4V 50 80 110 uA ENABLE EN EN Input High VEN H VEN rising 1 14 1 20 1 26 V d EN Input Low L VEN falling 1 05 V EN Input Leakage Current IEN VEN 5 5V 1 1 OSCILLATOR Switching Frequency 100kHz fsw RRT 150kQ 80 100 120 Switching Frequency 300kHz fsw RRT 49 9kQ 270 300 330 kHz Switching Frequency 1MHz fsw RRT 14 3kQ 0 9 1 11 2 Switching Frequency Adjustment Note 3 100 1000 kHz Range RT Voltage VRT RRT 49 9kQ 1 15 1 2 1 25 V PWM MODULATOR 2 Peak to Peak 15 V PWM Ramp Valley VVALLEY 15 V Minimum Controllable On Time 70 125 ns Maximum Duty Cycle fsw 300kHz RRT 49 9kQ 85 87 5 Minimum Low Side On Time fsw 1MHz RRT 49 9kQ 110 ns OUTPUT DRIVERS DRIVERS SUPPLY Undervoltage Lockout VDRV UVLO VDRV rising 4 0 4 2 4 4 V m Lockout 400 Low sinking 100 1 3 VBST VLX 5V DH On Resistance High sourcing 100mA 15 4 VBST VLX 5V Low sinking 100mA 1 3 VpRv Vcc 5 25V DL On Resistance High sourcing 100mA 15 4 VpRV 5 25V Sinking 3 VBST VLX 5V DH Peak Current CLOAD 10nF A Sourcing 2 VBST VLX 5V MAA MAX15046 40V High Perfor
3. 13 Generation System Finite Element Analysis Finite Element Analysis was completed on the shaft that would have the most likelihood to fail This is due to the large load of the flywheel on the shaft as well as the two intermediate sprockets There is a force of 50 lbs N in the center of the shaft where there would actually be a weight of 25 lbs There are also two torsion forces where the intermediate sprockets will go with a value of 22 Ib in where there would actually be only as much as 11 Ib in of torque Figures 6 7 and 8 below represent the deflection stress and factor of safety of the beam with exaggerated deflections The deflections are well below one thousandth of an inch This proves that the shaft will easily support the forces acting on it URES 38358 004 3552e 004 3 238 00 28148006 25900 0046 2 2578 004 13430 004 15190 004 1 2356 004 9 7148 005 6 4758 005 3 2388 005 Figure 6 von Mises psi 27435 25195 22908 20513 18331 1604 2 1375 4 11455 9177 6888 4500 2311 Figure 7 Fos Intermediate Sprocket Locations Flywheel Location 10000 Figure 8 14 Power Generation System Diagram procket with Freewheel Spring anl Spring Return Spool Intermediate Shaft Generator Motor 15 Power Generation System Diagram Cont Bearing Intermediate Sprogket Flywheel Return Spool Generator Motor 16 Po
4. Generator Motor Selection Ideal motor criteria 1 Reversible motor can act as a generator Motor Torque Gear Kite Tension Motor Power ded in lbf N m Ratio Ibf N watts 2 DC no AC DC inverter neede 1 0 0 113 7 4 35 156 30 76 3 Permanent Magnet powerful 2 0 0 246 7 0 7 0 31 1 61 53 M 3 0 0 369 7 0 10 5 46 7 92 29 4 Brushless less friction loss gen 4 0 0 492 7 0 14 0 62 3 123 05 5 Low rated RPM less gearing required 5 0 0 615 7 0 17 5 77 8 153 82 6 Continuous Duty made to run continuously 6 0 0 738 20 21 0 93 4 18158 7 0 0 861 7 0 24 5 109 0 215 34 Based on some basic lift and drag force 8 0 0 984 7 0 28 0 124 6 246 11 1 0 2 Y _1 2n equations L Fi CHA tension force SOLO 10 en from the kite onto the system was calculated In these er SY 522204 np 11 0 1 353 7 0 38 5 171 3 338 40 equations p is air ensity v is the wind speed A 12 0 1 476 70 42 0 186 8 369 16 characteristic area of the kite and C and C are the lift and 13 0 1 599 70 45 5 202 4 399 92 drag coefficients respectively The tension force was then 14 0 1 722 70 49 0 218 0 430 68 converted into a torque value 7 X F based 15 0 1 845 70 52 5 233 5 461 45 assumed values for sprockets used to gear the system Assuming a 4 diameter spring return mechanism The to
5. nt 4 the oscillatory pull of the kite on the p system Figure 2 The generator motor uses 25 roller chain therefore the sprockets must also use 425 roller chain The tension of the kite lines at maximum wind speed is 50 97 Ibs 226 75 as calculated from the lift and drag force equations stated earlier The working load of 25 roller chain is 140 Ibs 622 75 which gives a factor of safety of 2 75 for the chains The designed system gearing ratio will be 7 4 1 which will give a balance between the kite speed required and the torque the kite tension force will generate The Excel data and graph is shown on the following page in Figure 3 and Table 4 A fully assembled rear wheel assembly comes with the large sprocket combined with the freewheel and axle size needed as well as a wheel and tire that is not needed Two sprockets one 14 tooth and one 16 tooth a steel bar of inch diameter and two bearings for the intermediate shaft will be purchased The flywheel does not have a specific design as of yet From research it has been found that the heavier the flywheel the smoother the operation of the motor as long as the driving force is able to overcome the inertia of the flywheel The design portion on flywheels in the machine design text book is not clear in the actual process for designing the flywheels There are also no online resources that use an engineering approach to designing flywheels will continue to do more res
6. to 6V 0 3V to 0 3V DETTO 0 3V to VBST 0 3 All Other Pins to GND 0 3V to Vcc 0 3V Voc Short Circuit to 2 2 Continuous PGOOD Maximum Sink 20mA Continuous Power Dissipation TA 70 C 16 QSOP derate 9 6mW C above 70 771 5mW 16 QSOP EP derate 22 7mW C above 70 C 1818 2mW Junction to Case Thermal Resistance 0JC Note 1 16 0 37 C W 16 Pill QSOP EP a t 6 C W Junction to Ambient Thermal Resistance 0JA Note 1 16 PID OS OP E R 103 7 C W 16 Pity QSOP EP u a nenn Operating Temperature Range Junction Temperature Storage Temperature Lead Temperature soldering 105 300 Note 1 Package thermal resistances were obtained using the method described in JEDEC specification JESD51 7 using a four lay er board For detailed information on package thermal considerations refer to http www maxim ic com thermal tutorial Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device These are stress ratings only and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications
7. 1 on page 12 R2 is varied to find the radius of the large sprocket needed to attain a balance between kite speed Ks and force of the kite Fk A gear ratio that balances kite speed and force of the kite can be determined using the graph of Figure 3 This gives a gear ratio R2 R1 of approximately 7 4 1 Thus the kite will need to move around 6 5 feet per oscillation of the system based on Table 4 Freewheel and Return Mechanism The freewheel mechanism is a vital part of the generation system design Figure 4 shows how a basic freewheel mechanism works A freewheel allows free rotation in one direction but when spun in the opposite direction the system engages and allows energy transfer This means that the kite string when pulled out will engage the freewheel and transfer energy into the shafts and motor However when the kite is in the return stage of its oscillatory motion due to the spring return mechanism the kite string and the motor can move independently Engaged This system will use a freewheel that is already Figure 4 attached to a sprocket and axle on a rear wheel assembly of an electric scooter There are no force or life specifications on the freewheel that we will be using However it is assumed that this system will undergo far less stress compared to a high powered electric scooter that the part is made for The return mechanism is the system that will be used to retract the kite during each osc
8. Characteristic Value Active Current Consumption 10mA Output Impedance 1K ohms Maximum Measurable AC Current 30A Maximum Measurable DC Current 30A Maximum Measurable AC Frequency 10kHz Current Conductor Resistance 1 5mO Maximum Supply Voltage 5 5VDC Minimum Supply Voltage 4 5VDC Terminal Block Recommended Wire Size 10 26 AWG Wire Stripping Length 6 7mm Total Output Error 12596 Max between 40 C 85 C Total Output Error Typical 1 5 25 31 Battery Decision A large portion of the design decision was reliant upon the battery The system in creation not only needs to generate power but store it The chemistry of the battery chosen needs to be looked at closely to make sure it can handle the ruggedness of such a high power system Since it needs to be a battery that can be recharged the most likely possible battery chemistries for this system include NiMH lithium ion and lead acid After analyzing these battery types a few conclusions can be drawn NiMH batteries are too small in capacity and are rated at a current too small for the current project Lithium lon batteries would possibly work for the current project but are extremely expensive and would be way out of the budget The last choice is lead acid which applies satisfactorily to this project Lead acid batteries are rugged and can handle large voltages and currents Lead acid batteries even those rated into the dozens of amp hours are moderately affordable The
9. Output and Enable Input EN with 5 Accurate Threshold Thermally Enhanced 16 Pin QSOP Package Applications Industrial Power Supplies PLC Industrial Computers Fieldbus Components Fieldbus Couplers Telecom Power Supplies Base Stations Ordering Information PART TEMP RANGE MAX15046AAEE 40 C to 125 C 16 QSOP MAX15046BAEE 40 C to 125 C 16 QSOP EP Denotes a lead Pb free ROHS compliant package Exposed pad Typical Operating Circuit 45V TO 40V M OFF MAXIM MAXI5046 Vec PGOOD LX BST DL 0 6V TO 085V x Viy 4 I 02 En Y Y Maxim Integrated Products 1 For pricing delivery and ordering information please contact Maxim Direct at 1 888 629 4642 or visit Maxim s website at www maxim ic com MAX15046 40V High Performance Synchronous Buck Controller ABSOLUTE MAXIMUM RATINGS N to GND 45V Vcc to GND 6V EN DRV GND a eiecti eec mene 0 3V to 6V PGOOD to s 0 3V to 45V PENDT END ce 0 3V to 0 3V DL to PGND 0 3V to 0 3V BST to POND aiii eee 0 3V to 50V LX and 1V to 45V LX and CSP to PGND icici eri 2V 50ns max to 45V m 0 3
10. Overview 1 1 Features Delivers up to 5 A continuous 6 A peak current Optimized for DC motor management applications Operates at supply voltages up to 40 V Very low Ros on typ 200 25 C per switch Output full short circuit protected Overtemperature protection with hysteresis and diagnosis Short circuit and open load diagnosis with open drain error flag Undervoltage lockout CMOS TTL compatible inputs with hysteresis No crossover current Internal freewheeling diodes Wide temperature range 40 lt lt 150 C Type Ordering Code Package TLE 5205 2 Q67000 A9283 P TO220 7 11 TLE 5205 2GP Q67006 A9237 P DSO 20 12 TLE 5205 26 Q67006 A9325 263 7 1 TLE 5205 25 Q67000 A9324 P TO220 7 12 Description P TO220 7 12 The TLE 5205 2 is an integrated power H bridge with DMOS output stages for driving DC Motors The part is built using the Infineon multi technology process SPT which allows bipolar and CMOS control circuitry plus DMOS power devices to exist on the same monolithic structure Operation modes forward cw reverse ccw brake and high impedance are invoked from just two control pins with TTL CMOS compatible levels The combination of extremely low Rpg on and the use of a power IC package with low thermal resistance and high thermal capacity helps to minimize system power dissipation A blocking capaci
11. a eee ad in 48 Gantt Chart Spring 2010 INI elo ee or oes ee eget daci n deen 49 Appendices an DE 50 MAX15046 DC DE 8 4550 5 iie reiten ee ek acu Peek B TEE5205 2 Motor Controller een at eee dar ee dee e ea C Kite Wind Generator Requirements Specification Overview Our team will design and prototype a kite wind generator The generator will produce electrical power from the drag force applied to the kite by wind The kite will be autonomously guided by a microprocessor to perform the gliding maneuvers necessary to produce power A kite wind generator would be useful for generating power on large scale agricultural farms in remote locations for disaster relief or military or as a part of a larger wind farm Problem Statement Due to pollution and depletion of traditional energy sources there is a need to generate power from renewable energy sources Wind is the second most abundant energy resource next to solar energy that can be harnessed to generate power Kite wind generation is more effective than conventional turbines in gathering the energy from the wind for two reasons First the kite can reach much higher altitudes than turbines where the wind is more reliable and strong Second kites can cover more area in the s
12. from damage during output overloaded conditions or output short circuit faults without requiring a current sense resistor Hiccup mode current limit reduces power dissipation during short circuit conditions The MAX15046 includes a power good output and an enable input with precise turn on turn off threshold which can be used for input supply monitoring and for power sequencing Additional protection features include sink mode current limit and thermal shutdown Sink mode current limit pre vents reverse inductor current from reaching dangerous levels when the device is sinking current from the output The MAX15046 is available in a 16 pin QSOP or 16 pin QSOP EP package and operates over the 40 C to 125 C temperature range Pin Configurations appear at end of data sheet Buck Controller Features Input Voltage Ranges from 4 5V to 40V or 5V 10 Adjustable Outputs from 0 85 x ViN Down to 0 6V Adjustable Switching Frequency 100kHz to 1MHz with 10 1MHz Accuracy Adaptive Internal Digital Soft Start Up to 25A Output Capability Cycle by Cycle Valley Mode Current Limit with Adjustable Temperature Compensated Threshold 30mV to 300mV Monotonic Startup into Prebiased Output 1 Accurate Voltage Reference 3A Peak Gate Drivers Hiccup Mode Short Circuit Protection Patent Pending Architecture Overtemperature Shutdown 9 lt Power Good PGOOD
13. irrelevant to the application of the project The Hall Effect sensors seemed promising but it would have been a lot of extra design work to create the current sensor circuit which would be outside our time constraints Both the current and voltage ICs were found from a company called Phidgets which provides prebuilt circuits rated high enough to handle our power and still stay within our budget Once a way to monitor power was discovered the next roadblock was voltage and current regulation The Maxim MAX15046 is a 40V high performance synchronous Buck controller This chip while it is complex provided the exact regulation needed all for less than five dollars per IC This IC accepts an input voltage from 4 5V to 40V and outputs a fixed voltage that can be configured between the range of 6V to 85 of Vin It also provides up to a 25A output capability This will allow stable voltage to be provided to the battery In parallel with the battery there is a Zener diode to act as overcharge protection After the battery the sources run into other regulators that will provide ample voltage to the motors microprocessor and other IC chips Current Monitor Decision Hall Effect Criteria Weights Phidgets 30A Current Monitor Allegro ACS712 TIINA219 Current Monitor Effectiveness 0 4 8 Practicality 0 2 5 Time 0 25 2 Cost 0 15 9 Table 8 current monitor mechanism decision matrix 20 501 9 AS
14. is not implied Exposure to absolute maximum rating conditions for extended periods may affect device reliability ELECTRICAL CHARACTERISTICS VIN 24V VEN 5V VGND VPGND OV CIN noted Typical values are at TA 25 C Note 2 1uF 4 7yF RRT 49 9 TA Ty 40 C to 125 C unless otherwise PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS SYSTEM SPECIFICATIONS 45 40 Input Voltage Range VIN VON 45 55 V Quiescent Supply Current VIN 24V VFB 0 9V no switching 2 3 mA Shutdown Supply Current E 0 35 0 55 Vcc REGULATOR Output Voltage Vvcc 6V x VIN x 40V ILOAD 6mA 5 5 25 5 5 V Regulator Dropout VIN 4 5V ILOAD 25mA 0 18 0 45 V Vcc Short Circuit Output Current VIN 5V 30 55 90 mA Vcc Undervoltage Lockout VCCUVLO Vvcc rising 3 8 4 4 2 V Her Lockout 400 mU ERROR AMPLIFIER FB COMP FB Input Voltage Set Point VFB 584 590 596 mV FB Input Bias Current VFB 0 6V 250 250 nA FB to COMP Transconductance gM ICOMP 20 600 1200 1800 uS Open Loop Gain 80 dB Unity Gain Bandwidth pm Hom COM tee 5 MHz MAKII 40V High Performance Synchronous Buck Controller ELECTRICAL CHARACTERISTICS continued 2 VIN 24V VEN 5V VGND VPGND
15. only disadvantage to lead acid batteries is that a deep discharge can cause an extreme memory loss The battery chosen is a 12V 26Ah sealed lead acid battery and was purchased for around 50 00 Access SLAA1224F Battery is rated at 12Volts 26Ah rating The Access SLAA1224F Battery from AtBatt com deliver power when you need it and where you need it It has been specially designed to meet the power needs of your Access SLAA1224F and is maintenance free easy to handle rugged and economical It has a characteristic of high discharge rate wide operating temperature long service life and deep discharge recover Amstron 12 volt 26Ah valve regulated sealed lead acid batteries are maintenance free rugged and economical Amstron SLA batteries are utilized in a wide variety of applications including electric vehicles wheelchairs scooters UPS backups computer systems industrial and medical equipment and more Delivering power when you need it the AP 12260R uses a state of the art heavy duty calcium alloy grid that provides exceptional performance and service life in both float and cyclic applications Absorbent Glass Mat AGM technology for superior performance Valve regulated spill proof construction allows safe operation in any position High energy density Approved for transport by air UL recognized under file number MH47341 Specifications Chemistry Lead Acid Voltage 12 Capacity 26 000 mAh 26 Ah Rating 312 Whr Conne
16. sensor shuts down the device forcing DL and DH low which allows the device to cool The thermal sensor turns the device on again after the junction temperature cools by 20 C The regulator shuts down and soft start resets during thermal shutdown Power dissipation in the LDO regulator and excessive driving losses at DH DL trigger thermal overload protection Carefully evaluate the total power dissipation see the Power Dissipation section to avoid unwanted triggering of the thermal overload pro tection in normal operation Applications Information Effective Input Voltage Range The MAX15046 operates from 4 5V to 40V input supplies and regulates output down to 0 6V The minimum voltage conversion ratio VOUT VIN is limited by the minimum controllable on time For proper fixed frequency PWM operation the voltage conversion ratio must obey the following condition V 90 MIN fsw IN where tON MIN is 125ns and fsw is the switching fre quency in Hertz Pulse skipping occurs to decrease the effective duty cycle when the desired voltage conversion does not meet the above condition Decrease the switch ing frequency or lower the input voltage VIN to avoid pulse skipping MAKII Buck Controller The maximum voltage conversion ratio is limited by the maximum duty cycle Dmax VOUT _Dmax x VoRop2 1 Dmax VDROP1 lt Dmax VIN VIN where VDROP1 is the sum of the parasitic voltage drops in the inductor dis
17. the stored energy as the inductor current ramps down pro viding current to the output Under overload conditions when the inductor current exceeds the selected valley current limit threshold see the Current Limit Circuit LIM section the high side MOSFET does not turn on at the subsequent clock rising edge and the low side MOSFET remains on to let the inductor current ramp down Internal 5 25V Linear Regulator An internal linear regulator provides a 5 25V nal supply to power the internal functions and to drive the low side MOSFET Connect IN and Vcc together when using an external 5V 10 power supply The maximum regulator input voltage VIN is 40V Bypass IN to GND with a 1uF ceramic capacitor Bypass the output of the linear regulator VCC with 4 7uF ceramic capacitor to GND The dropout voltage is typically 180mV When VIN is higher than 5 5V is typically 5 25V The MAX15046 also employs an undervoltage lockout circuit that disables the internal linear regulator when falls below 3 6V typical The 400mV UVLO hysteresis prevents chattering on power up power down MOSFET Gate Drivers DH DL DH and DL are optimized for driving large size n channel power MOSFETs Under normal operating conditions and after startup the DL low side drive waveform is always the complement of the DH high side drive waveform with controlled dead time to prevent crossconduction or shoot through An adap
18. the lowest possible DC resistance that fits in the allotted dimensions The 14 saturation current rating ISAT must be high enough to ensure that saturation cannot occur below the maximum current limit value given the tolerance of the on resistance of the low side MOSFET and of the LIM reference current ILIM Combining these conditions select an inductor with a saturation current ISAT of ISAT 2 1 35 xICL where ICL TYP is the typical current limit set point The factor 1 35 includes RDS ON variation of 25 and 10 for the LIM reference current error A variety of inductors from different manufacturers are available to meet this requirement for example Vishay IHLP 4040DZ 1 5 and other inductors from the same series Setting the Valley Current Limit The minimum current limit threshold must be high enough to support the maximum expected load current with the worst case low side MOSFET on resistance value as the RDS ON of the low side MOSFET is used as the current sense element The inductor s valley current occurs at ILOAD MAX minus one half of the ripple current The minimum value of the current limit threshold voltage ViTH must be higher than the voltage on the low side MOSFET during the ripple current valley LIR gt Rps ONMAX XILOAD MAX 1 2 where RDS ON MAX in Q is the maximum on resistance of the low side MOSFET at maximum load current ILOAD MAX and is calculated
19. with shipping This slider meets the length requirements of a 9 9 inch travel length Kite Retraction System Design The purpose of the kite retraction system is to deploy and retract the kite when the user so desires or to retract the kite when wind speed is either too high for safety or too low for flight gt 50 kph 6 kph Two designs were considered one using a motorized big game fishing reel and the other using a simple motor and drum set up A decision matrix was created to help in the decision process and is shown in table 11 Attribute Weight Fishing Reel Simple Drum Cost 50 00 6 10 Simplicity 30 00 7 10 Consistent Line Intake 20 00 10 7 Total 100 0096 71 0096 94 0096 Table 11 Kite Retraction Decision Matrix NOTE Ratings are on a 0 to 10 scale where 0 is least desirable and 10 is the most As is shown above the decision was made to go with a simple drum In the design specifications the retraction time is set to be no less than 10 minutes Using equation 3 it has been 42 calculated that the maximum rated tension on the kite during retraction when the only force on the kite will be due to lift is equivalent to 28 13 rounded up about 7lb A spreadsheet shown in table 12 was made to find the appropriate spool dimensions rpm and torque for these requirements FL Where C is the lift coefficient equal to about 0 15 Axis the kite area 2m p is the densi
20. 2 5 60 hr Whretract 6v 24 19A 5 60 hr 12 77 Wh 43 This is insignificant because in the event of a case where wind speeds are high enough to produce such lift forces on the kite the power generated due to those same high winds would offset any losses due to the retraction of the kite FIRST CIM Motor Figure 39 Retraction Motor Operating v 6v 12v Nominalv 12v No Load RPM 5310 No Load A 2 7 Stall Torque 343 27 oz in 2424 mN m Stall Current 133A Kt 2 58 oz in A 18 2 mN m A Kv Efficiency 6596 RPM Peak Eff 4614 Torque Peak Eff Current Peak Eff 443 rpm V 45 oz in A 19 8A 317 8 mN m The kite reel system will also act as the kite break system The cost of parts for the spool drum will be insignificant due to the fact that its parts can be found in a common junk yard or even made out of PVC pipe The value of the spool will be recorded in our records but budget will not suffer Figure 40 Retraction System Spool Drum radius 1 7 cm 2 in CIM Motor 44 Budget Analysis Currently 33 3 of the budget has been used by spending 283 09 A large number of purchases will be made within the next week so that majority of the required parts for the system will be purchased Vendors have been selected for all the parts of the project Some of the more expensive items e Kite e Generator Motor e Development Board e Battery These are some of the mor
21. A will be considered constant and are to be measured as shown in figure 32 A figure eight flight path was chosen because it readily delivered the repetitive power zone enter and exit pattern As was stated previously the path should be scaled with wind speed A depiction of such a path is shown in figure 23a This path is ideal because of the power zone shown previously in figure 23b The kite flies into the red power zone delivering maximum tension pulling the freewheel and generating electricity Next the kite flies into the low tension light blue zone allowing the free wheel to retract the kite loops back and the process is repeated 38 Controls Kite String Manipulator Design The kite s flight is manipulated by pulling the right line IN while letting the left line OUT to turn CW and pulling the left line IN while letting the right line OUT to turn CCW To accomplish this a slider controller is designed such that the linear movement of the slider causes the above mentioned maneuvers Our designed controller is depicted in figure 33 Electric Motor Kite String Figure 33 Slider Controller Design The slider controller is depicted from above in figure 34 It can be seen that when theta equals zero the line length Y can be calculated to be equal to twice that of the slider position X For example as the slider moves distance X to the right the right line will bet let out distance 2 X and the left line will be taken
22. Control system 1 11 2010 2 9 2010 41 512 1 26 2010 2 16 2010 51 3 51 4 51 5 51 6 Generator motor 7 1 1 2000 2 2 2010 51 8 SEA charge Controller 17257201 51 10 1 19 201 16 66 153 51 11 2 2 2010 2 23 2010 51 12 52 0 3 15 2010 4 6 2010 53 0 54 0 55 0 56 0 4 26 2010 57 0 4 13 2010 4 26 2010 58 0 4 13 2010 4 27 2010 ALO 15 3 A2 0 1 11 2010 4 29 2010 1 1 2010 ye91g uy N w w e w Apr 2010 N N N Appendices Appendix A MAX15046 DC DC Converter 19 4719 Rev 0 7 09 MAKII 40V High Performance Synchronous General Description The MAX15046 synchronous step down controller oper ates from a 4 5V to 40V input voltage range and gener ates an adjustable output voltage from 85 of the input voltage down to 0 6V supporting loads up to 25A The device allows monotonic startup into a prebiased bus without discharging the output and features adaptive internal digital soft start The MAX15046 offers the ability to adjust the switching frequency from 100kHz to 1MHz with an external resis tor The MAX15046 s adaptive synchronous rectifica tion eliminates the need for an external freewheeling Schottky diode The device also utilizes the external low side MOSFET s on resistance as a current sense element eliminating the need for a current sense resis tor This protects the DC DC components
23. SHUTDOWN Thermal Shutdown Threshold Temperature rising 150 C Thermal Shutdown Hysteresis 20 C Note 2 All devices are 100 tested at room temperature and guaranteed by design over the specified temperature range Note 3 Select RRT as 17 3 109 few 1 x 1077 Ej where fsw is in Hertz MAKINI MAX15046 40V High Performance Synchronous Buck Controller Pin Description PIN NAME FUNCTION y IN Regulator Input Connect to the input rail of the buck converter Bypass IN to PGND with a 100nF minimum ceramic capacitor When operating in the 5V 10 range connect IN to Vcc 5 25V Linear Regulator Output Bypass Vcc to PGND with a ceramic capacitor of at least 4 7uF 2 Vcc when Vcc supplies MOSFET gate driver current at DRV 2 2uF when Vcc is not used to power DRV 3 PGOOD Open Drain Power Good Output Pull up PGOOD to an external power supply or output with an external resistor 4 EN Active High Enable Input Pull EN to GND to disable the buck converter output Connect to for always on operation EN can be used for power sequencing and as a UVLO adjustment input 5 LIM Current Limit Input Connect a resistor from LIM to GND to program the current limit threshold from 30mV 6kQ to 300mV 60kQ 6 COMP Error Amplifier Output Connect compensation network from COMP to FB or from COMP to GND 7 FB Feedback Input Invert
24. Second Wind Final Design Dec 8 2009 Josh Dowler Caleb Meeks John Snyder Table of Contents Requirements Specification 3 ECCE 5 iple fas 6 Organization and 7 Generator Motor Selection rideo Petre tp dl dre ie eet sus Ro vc er dae p eR REN CREE 8 Sprockets arid Chains te ree pere ite er e e ove eere ene 9 Motor and Gearing Calculations aaaeeeaei ainena kiria itik etaar esete r renin naiki kirarkan ksr N i saan 11 Freewheel and Return Mechanisms 12 Generation Stress Concentration POINTS 14 Generation System a 15 Charge Controller Desig oet dal ede bud 20 Microprocessor Desig ui re Rente o sere b aie tes Re 25 Software Designer a dein 27 Motor Controller Desi RE ede ee eta dede deb eigene tede lE 30 Electrical e bees tel 31 Electronically Assisted Design dee aee ern insbes nn 33 Kite Retraction System Design nenn ee pre re don 43 Budget Analysis ari reci roter Pure rele re eda ee rea ee rend OS 45 Updated RN 46 Schedule Analysis iii di 47 Gantt Chart Eall 2009 ne eel p ee p ete ere i eee eee
25. ain Retract Switch No Mode Change Calculate Spool Motor Movement Move Spool Motor Software Flowchart cont d START gt gt Find Kite Angles Get current voltage values Calculate Motor Movement Calculate power P V i Move Control Motor Get Kite String Length and Line Tension Check Ascend Sustain Retract Switch Output Power and Kite String Length to LCD No Mode Change Check Kite Calculate Spool Motor Movement Recalibrate Kite Move Spool Motor Figure 19 detailed system flowchart 29 Motor Controller Choosing a motor controller configuration is highly dependent upon the types of motors being used Two different motors need to be chosen for the current project One motor the reel motor will control the spool that allows the kite to ascend sustain or retract The other motor will adjust the kite controls according to the kite control algorithms The motor chosen for the reel is a typical 12V DC motor and the control motor is a 1 76V 2A stepper motor that changes at 8 per degree change The reel motor will be controlled by an Infineon 5205 2 motor controller chip This chip is a 5A output H bridge made for DC motor management applications This chip will acc
26. ated as the difference of the work done by the slider to pull one line in and the work done on the slider by the other line going out From the free body diagram in figure 37 we can see that Plugging this into the work equation we get Wiotal Fs x Tu 2 Fs 2 TR Friction Miystem 9 slider Wiotal 2 Ta Friction M system Aslider FX 2 n es gt Figure 37 Slider Controller FBD 41 Assuming Tr T this can simplify to Wiotal Friction M system Aslider x We see that the amount of work done by the slider will primarily be a function of friction in the system and the mass and acceleration of the system It can be assumed that any slider purchased will already be able to move its own weight The only other mass in this system is that of the kite and the strings which are negligible In conclusion special attention to the frictional losses to be overcome by the controller must be considered in the final selection of small parts that the strings run through such as pulleys and eye holes The current slider design is made of the components shown in figure 38 Belt Slider Rail Truck travel 13 inches Cost 45 including shipping Figure 38 Belt Slider Rail A motor was purchased to run this slider The motor is rated at 1 76V 2A and turns at 0 8 deg per revolution A cog pulley came with the motor that will mate with the belt drive This motor coasted 35
27. ation programmed into memory This number will then be stored to memory The program will then reading the input switch sensor for the kite string and line tension using A D inputs These values will then be stored to memory as well The kite string length and generate power will then be taken out of memory and be translated to allow it to be exported to the LCD screen The export to the screen will then take place Once the LCD screen has been updated the software will begin the check kite algorithm The software will first read in the values of the kite angle potentiometers and calculate the kite string angles These angles will then be compared with the kite flight algorithms to determine the next move These movements will then be applied to the control motors to control the kite The user three way switch is then checked to see if the kite needs to be retracted or ascended If it needs to change an output to the spool motor will be applied This whole process is then repeated 27 Software Flowchart START Get current voltage values Calculate power P V i Get Kite String Length and Line Tension Output Power and Kite String Length to LCD Check Kite Recalibrate Kite Figure 18 basic system flowchart m Find Kite Angles Calculate Motor Movement Move Control Motor Check Ascend Sust
28. be checked on a constant basis and be locked in a continuous loop to keep the kite in flight The only exceptions will be user mode changes from the user interface This switch will trigger interrupts in the microprocessor and alter the flow of the program which will resume once the interrupt is completed In figure 17 the string length switch is represented as a simple switch This will be a ticker switch which will click each time the reel spool rotates In figure 17 there are also four potentiometers used to represent the kite angle sensors As the resistance of these changes the input voltage will change telling the microprocessor the angle change of the string There are two angle sensors for each string one for vertical angle and one for horizontal angle Another potentiometer for the tension sensor is used in figure 17 This is a resistor that varies with the pressure placed on it and will be used to find the tension in the kite strings The voltage and current sensors will be inputs that vary from 0 5 volts These sensors will take a reading on the voltage and current generated by the generator motor and convert that reading to a 0 5 volt signal The user interface contains a simple three way switch that will allow the user to select between three modes The LCD screen will utilize six input output pins of the microprocessor The motor controls will utilize six input output pins as well Microprocessor Decision MicroChip STARTER DEMO Futurl
29. budget The updated budget has allocated 91 82 or 10 8096 of the total budget as a buffer in case of unpredicted expenditures in the future So as of now the project is still on budget 45 Product Vener Ordered Nus Bots Wood 55000 Ae iw __ n Circuit Boards ____ 55000 Electrical Components allelectronies com 32500 Miscellaneous 5728 Figure 41 47 Schedule Analysis Having a retrospective look at our semester has given us essential insight for the remainder of our project s development After the completion of our Requirements Specification our project was well under way Research began to become more intensive and creativity was vital As we continued to meet deadlines our first accomplishment was the successful delivery of our Stage Gate Presentation as well as the completion of our Final System Overview and Project Plan Once this was completed deadlines became more reliant upon the timeframes our own group established We are persisting through the final steps in the design process Hands on models circuit simulations and schematics 3 D Solidworks models and analyses and overall systems analyses have been completed Analyses of Solidworks models and circuit diagrams have taken place in order to justify our design choices There are currently still finalizations being made to a few subsystems but this should not cause many future delays These finalizati
30. charge path including synchronous rectifier inductor PCB resistance VDROP2 is the sum of the resistance in the charging path including high side switch inductor and PCB resistance In prac tice provide adequate margin to the above conditions for good load transient response Setting the Output Voltage Set the MAX15046 output voltage by connecting a resis tive divider from the output to FB to GND Figure 2 Select R2 from between 4kO and 16 Calculate R1 with the following equation ven FB where VFB 0 59V see the Electrical Characteristics table and VOUT can range from 0 6V to 0 85 x VIN Resistor R1 also plays a role in the design of the Type compensation network Review the values of R1 and R2 when using a Type Ill compensation network see the Type Compensation Network Figure 4 section FB MAXIM MAX15046 Figure 2 Adjustable Output Voltage 13 MAX15046 40V High Performance Synchronous Buck Controller Setting the Switching Frequency An external resistor connecting RT to GND sets the switching frequency fsw The relationship between fsw and RRT is 17 3x10 few 1x10 7 x few where fsw is in kHz and RRT is For example 300kHz switching frequency is set with RRT 49 9kQ Higher frequencies allow designs with lower inductor values and less output capacitance Peak currents and 2 losses are lower at higher switching frequencies but core
31. ctor R Terminal Length 6 54 inch 16 61 cm Width 6 89 inch 17 50 cm Height 4 92 inch 12 50 cm Color Gray Weight 18 08 lb 8 200 91 Warranty 1 Year UPC Code 880487220654 Figure 22 Amstron 12V 26Ah Sealed Lead Acid Battery w R Terminal 32 Electronically Assisted Design Power from the wind is harnessed from the drag force and movement of the kite parallel to the kite strings through the power generation system A kite flight pattern that allows the wind to produce this force and movement thereby transferring power is necessary It is also important that this power is delivered in a repeatable method From the equation for the drag force parallel to the kite strings equation 1 we see that the force is a function of how much of the kite area is perpendicular to the wind This renders the power zone as shown is figure 23b where the area hence forces are greatest A kite flying repeatedly in and out of the power zone would produce a figure eight path such as is shown in figure 23a This path delivers alternating in and out movements that pull the freewheel to generate electricity and then allow the freewheel to be retracted in preparation for another generation pull the wind window Figure 23a Sample Flight Path in 3D Figure 23b Power Zone To produce this power generating flight path software sensors and electromechanical means will be used The kite controls sensors will send analog tension sensor and sph
32. d by the trend lines a program was written in LabView to convert the measured resistance to an angle measuring device in LabView The resulting graphs are shown in Figure 26 and Figure 27 below 120 100 80 60 Phi degrees 40 20 y 0 2369x 199 88 0 T T T T T T T T 1 0 100 200 300 400 500 600 700 800 900 R ohms Figure 26 Phi vs R 35 200 180 160 140 120 100 80 60 40 20 Theta degrees 0 2557x 232 61 0 200 400 600 800 1000 R ohms Figure 27 Theta vs R The results of the program written in LabView for Phi are shown in Figure 28 and the results for Theta are in Figure 29 below Figure 28 Results for Theta Figure 29 Results for Phi From Figures 26 and 27 we can see that the resistance change with angle is in fact linear This fact is confirmed by the angles indicated in the LabView program output seen in Figures 28 and 29 The angles read using the program were close if not identical to those observed on the test platform The pros of this method of measuring the O and are that it is relatively inexpensive and easy to construct Possible cons of this method are that is it mechanically intensive could have problems with dust rust etc There could also be a problem with drift depending on the quality of the potentiometer used This is a very good potential method of measuring the angles of the
33. e important items that were required in order to further the research and development of the project The generator motor was expected to be more expensive so this was an unexpected saving The budget previously listed the use of used bicycle parts for items such as sprockets chains and axles However the design now calls for the use of sprockets and chains of different pitch from a bicycle system However due to the low cost of the motor the sprockets and chains still fit within the budget of the generation system The battery design was changed from one that could hold 500 watt hours of energy to one that can hold just over 300 watt hours of energy This design change was done in order to save on the cost of the battery The system will still be able to show that it can produce 500 watt hours of energy within a ten hour period A development board was purchased instead of individual microprocessors to allow for ease and speed of programming The change proved more expensive however the microprocessor that comes with the development board has free samples that can be obtained Another major change to the budget comes from the controls system It was determined that the most accurate and effective way to control the kite would be by using a system similar to that used on computer numerical control CNC machines These slider controller mechanisms can be purchased on ebay however they are expensive and will therefore be a larger part of our
34. e power in winds from 10 45 kilometers per hour Setup including kite deployment should take no more than 30 minutes Power generation should occur within five minutes of kite deployment System must have deploy sustain and retract modes of operation Autonomous control of each mode deploy sustain retract User interface to enable user to specify modes of operation deploy sustain retract and show user length of line released within one meter and power generated within 20 watts Must be able to sense length of line released within one meter and power generation within 20 watts 3 SO Ole System will be able to fit through a standard door frame with width of one meter and height of two meters Design Deliverables User manual Drawings and schematics with analyses Kite generator unit User interface Parts list with associated costs Test report Final technical report System Test Plan Kite stays aloft in winds of 10 45 kilometers per hour 10 minutes of autonomous flight and power generation in winds of 10 45 kilometers per hour Generation of 500 watt hours DC within 10 hours The electrical system will have a fail safe mechanism that will enable in case of a power surge Kite retraction of less than 10 minutes in winds of 10 45 kilometers per hour Shows accurate value for length of line released by comparing it with a tape measure within one meter Shows accurate value for power generation within 20 watts by
35. earch on the design of flywheels 10 Motor and Gearing Calculations Mt in Ibs R1 inch R2 inch R3 inch Fk lbs Mr RPM Ks in min Ks ft sec 05 15 al 165 2750 11519 07 1600 n 05 16 2 176 2750 1079922 1500 os 1 2218 2750 1016398 1412 20 9 2150 9094 08 12 22 270 863938 1200 HE M 24 05 23 05 24 nl al 253 2750 751250 1043 l 2 24 2750 77487771000 L 77 7 mm 2 mw m os 26 2 286 6645 6 t os 27 2 297 8 6170 9 5958 1 5759 5 5573 7 5399 6 5235 8 7 74 7 5 7 2 3 28g 25 8 Nm ze gt 4936 a of ost aa 2 os II ET 867 ees 545 os 34 2 4i8 2750 4570 632 t 04 304 2 429 2750 443044 645 05 4 2 Al 2750 4496 600 os y 2f 491 270 4243 545 2 462 270 411399 571 ____2 473 2750 40183 558 a 484 275 3969 545 2 45 275 383972 533 2 56 2750 375625 522 a 3676 53 511 os 42 05 43 os 44 45 o 46 905 47 05 48 l 1 I 1 05 l 11 4 Force of the Kite vs Kite Speed Desired Gear Ratio 7 4 1 Kite Speed ft s 30 40 Force of the Kite Fk Ibs 11 The variables in Table 4 are defined in Figure
36. ec MicroChip Development Individual MicroChip Criteria Weights BOARD KIT Board PIC18F4550 Effectiveness 0 4 9 9 8 Practicality 0 2 8 9 7 Time 0 25 8 9 1 Cost 0 15 1 3 9 TOTALS Table 8 microprocessor selection matrix 25 es YSTIONLNOO YOLON m 3 om JosuUsg uoisua 4 siosues 9 ejbuy Buys con OAL 05 mi vn 0S m vu sal swe JOSUsS waung pers 1 AS Bus LA peray uiejsns kx pusosy yams M e eyelu JOS HOSS30OSHdOMWOIIN Figure 17 microprocessor circuit diagram 26 Software Design The actual flow of the software is currently becoming more detailed in development The kite flight test data is still currently being turned into a mathematical model that can easily be manipulated for software applications All of the sensors will have to be checked on a constant basis and be locked in a continuous loop to keep the kite in flight The only exceptions will be user mode changes from the user interface This switch will trigger interrupts in the microprocessor and alter the flow of the program which will resume once the interrupt is completed The software system will begin by reading the input A D ports from the voltage and current sensors to monitor the power generated It will then calculate the power with an equ
37. ept PWM signals from the microprocessor and will turn the motors on and off based upon the inputs received which are set in the programming of the microprocessor The motors will not need to vary in speed only in direction so only the duration the motor is on will need to be adjusted by the software of the microprocessor Functional Truth Table OUT2 L Motor turns clockwise Comments H Motor turns counterclockwise L Brake both low side transistors turned ON 2 Open circuit detection Table 9 function truth table of TLE205 2 The control motor can be controller with inputs and outputs from the microprocessor A set of binary codes are programmed and repeatedly sent to the motor to allow it to move to exact specification A stepper motor is good for the current application because it allows the system to know exactly how far the controls are moving 30 Electrical Components LCD16x2 16 x 2 Character LCD Display futurlec com Figure 20 16x2 display Features 16 Characters x 2 Lines 5 x 7 Dots with Cursor in Controller Power Supply Also Available for 3V 1 16 Duty Circle Phidget 30 AMP Current Sensor AC amp DC trossenrobotics com rent Sensor e 05 Figure 21 30A current sensor The formula to translate SensorValue into Current is DC Amps SensorValue 13 2 37 8787 AC RMS Amps SensorValue x 0 04204 Device Specifications
38. erical position signals to the microprocessor The electromechanical controls physically control the kite flight through manipulation of the kite string lengths Fo 4 Where Cp is the drag coefficient equal to about 1 2 Axis the kite area 2m is the density of air at 1 2kg m and V is the wind speed Controls Sensors Design The sensory requirements for autonomous control of the Second Wind system stand on three legs First the location of kite must be sensed second the velocity vector of the kite must be sensed and finally a desired location or path of the kite must be predetermined The effects of wind speed are discussed below The kite s location can be conveniently measured in spherical coordinates using the kite string length for the radius and sensors attached to the kite strings to sense angles and as depicted in figure 24 thus giving the kite s location in spherical coordinates 33 Figure 24 Kite in Spherical Coordinates Kite velocity vector can be measured by the microprocessor by comparing the change in kite location over time The accuracy of this method will be affected by the sample rate of the kite location A single cycle of the flight path was measured to be about 5 seconds with wind speeds around 16 kph 10 mph If the sample rate is too slow say 1 Hz the information is too old to be useful and if the sample rate is too fast say 10000 Hz the information w
39. eutral The wind is assumed to be parallel to the ground thereby causing drag force normal to the inside of the kite We can see that because of the slightly tiled orientation of the kite to the wind the component of the drag force in the y direction must cause acceleration of the kite in an ark about the z direction As the kite flies forward we also see a lift force acting due to the parafoil shape Motion Figure 35 Kite FBD With Control Slider at Neutral In figure 36 we see an example of a right turn When the slider is moved to the left the right string is retracted and the left string is given slack This re orients the kite to the wind such that the drag force normal to the kite now has a component along the z axis The aerodynamic design of the kite causes the kite to turn about the x axis as is moves along the z axis 40 Motion R Figure 36 Kite FBD With Right Turn If we assume that the drag force and lift force along the x axis are at the center of the kite that the kite strings are at an equal distance Reenter from the center and that there is no movement in the x direction then we can say from statics that Ta and T are equal and there is no difference in line tension 2My Ti Reenter Reenter Therefore we can say that there will be no holding force needed The work required to make the line length change can be calcul
40. from the following equation Rps ONMAX Ros on 1 TCwosrer Tmax where RDS ON in is the on resistance of the low side MOSFET at ambient temperature TAMB in degrees Celsius TCMOSFET is the temperature coefficient of the low side MOSFET in ppm C and TMAx in degrees Celsius is the temperature at maximum load current ILOAD MAX Obtain the RDS ON and TCMOSFET from the MOSFET data sheet MAKII 40V High Performance Synchronous Connect an external resistor RLIM from LIM to GND to adjust the current limit threshold which is temper ature compensated with a temperature coefficient of 2300ppm C The relationship between the current limit threshold and RLIM is 10x VITH 50x1078 x 1 2300 TMAX Tame Rum where RLIM is in Q VITH is in V TMAX and TAMB are in C RLIM resistance range of 6kQ to 60kQ corresponds to a current limit threshold of 30mV to 300mV Use 1 tolerance resistors when adjusting the current limit to minimize error in the current limit threshold Input Capacitor The input filter capacitor reduces peak current drawn from the power source and reduces noise and voltage ripple on the input caused by the switching circuitry The input capacitor must meet the ripple current requirement IRMS imposed by the switching currents as defined by the following equation sea Vout Vin Vout MAX V IN IRMS attains a maximum value when the in
41. he force coming in from the lines needs to be geared up to supply the rated RPMs of the motor The use of belts and pulleys were Attribute weight chains Betts considered along with chains and sprockets _ os A s However it soon became apparent that Efficieny o2 dd belts and pulley are much more expensive availabitty sf 5 and difficult to find in varying sizes The Durability __ 7 5 efficiencies of chains and belts are both pun ppp above 95 so this was not a factor A Toal i 74 58 decision matrix was used to analytically Table 3 make this decision Chains are obviously the better choice for this system The initial design used only one shaft on which a large gear would sit with the return mechanism and directly connect to the motor Figure 1 However it was soon determined that the addition of an intermediate shaft was necessary to allow for proper use of the freewheel mechanism when connected to the large sprocket Figure 2 The intermediate shaft which contains two sprockets and a flywheel connects the drive shaft and the Figure 1 motor sprocket This means that the first shaft contains the spring return Freewheel connected to R2 mechanism and the large sprocket 5 connected to the freewheel system Flywheel 2 7 This configuration in conjunction with the flywheel allows the intermediate shaft and therefore the motor to continue spinning between
42. hronous Buck Controller Detailed Description The MAX15046 synchronous step down controller oper ates from a 4 5V to 40V input voltage range and gener ates an adjustable output voltage from 85 of the input voltage down to 0 6V while supporting loads up to 25A As long as the device supply voltage is within 5 0V to 5 5V the input power bus VIN can be as low as 3 3 The MAX15046 offers adjustable switching frequency from 100kHz to 1MHz with an external resistor The adjustable switching frequency provides design flex ibility in selecting passive components The MAX15046 adopts an adaptive synchronous rectification to elimi nate external freewheeling Schottky diodes and improve efficiency The device utilizes the on resistance of the external low side MOSFET as a current sense element The current limit threshold voltage is resistor adjustable from 30mV to 300mV and is temperature compensated so that the effects of the MOSFET RDS ON variation over temperature are reduced This current sensing scheme protects the external components from damage during output overloaded conditions or output short circuit faults without requiring a current sense resistor Hiccup mode current limit reduces power dissipation during short circuit conditions The MAX15046 includes a power good output and an enable input with precise turn on off threshold to be used for monitoring and for power sequencing The MAX15046 features internal digital soft s
43. ill be no more than noise A tentative sample rate of 40 Hz is proposed giving 200 samples in one cycle This sample rate will be tested and updated in the future Lastly the predetermined path shall be a flight pattern s coordinates that are stored in the microprocessor In order for this pattern to be useful in variable wind conditions it must be scaled in real time proportional to wind speed Two options for location velocity sensors were compared using a decision matrix as shown in Table 25 Attribute Weight Potentiometer Inclinometer Cost 40 00 10 5 Simplicity 40 00 7 6 Reliability 20 00 7 10 Total 100 0096 82 00 64 00 Table 10 Location Velocity Sensor Decision Matrix NOTE Ratings are on a 0 to 10 scale where 0 is least desirable and 10 is the most A test mock up of the potentiometer sensor was made and its applicability was established The test platform was constructed using two potentiometers various lego parts and two protractors such that the and angles of a single angle arm could be measured This test platform is depicted in Figure 25 below 34 Samples of the potentiometer s resistances at the angles 0 10 20 30 on until 180 degrees were taken recorded and graphed Similarly samples of the O potentiometer were taken at angles 0 10 20 30 on until 110 degrees were taken recorded and graphed Trend lines for each graph were made Using the equations generate
44. illation of the kite through its figure eight pattern The return mechanism consists of a spring that will store some of the energy of the kite into potential spring energy when the kite is on its outward pull The potential spring energy will then be released when the kite is on the outside of its figure eight flight pattern which will be discussed later and the kite will be retracted to its original position Kite dinge 72 The spring return mechanism is more difficult to design due to the need String Connecting for a constant kite pull out length at Spring and Variable Shaft varying wind speeds R3 Figure 2 Diar CEPS penis needs to remain constant at 2 inches due to the gearing ratio already being selected The values for the force of Attached Spring the kite are already known as shown in Table 5 The cheapest and easiest way Variable Diameter to allow the kite to have a constant pull Spools for Spring out length at varying wind speeds is to Return Mechanism vary the spring constant k of the spring Under the budget of this Figure 5 12 project the best way to do that is to have the Fmin lbf R3 i k Ibf in AX i RO i operator manually adjust the spring for the 60 in que inl in 3 48 200 2 95 9 42 0 25 current relative wind speed Setting the 3 48 2 00 1 31 1414 0 38 torque of the kite on the shaft equal to the 3 48 200 0 74 18 85 0 50 3 48 200 0 47 23 56 0 63 torque a spring on the shaft allowed i
45. in distance 2 X The converse is true of the slider moving to the left This effectively Figure 34 Slider Controller Design From Above 39 turns the kite This design is particularly advantageous as line tensions increase because the tensions will for the most part cancel each other leaving the majority of the power required to move the control slider This is only valid as the angle approaches zero so that the distance D between the eye hole and the side pulley is the same as the diameter of the central pulleys The length of a standard kite control bar is 50cm The most extreme turning angle achievable with this control bar is reached when the bar is parallel with the kite string That is to say one side of the bar has been pulled away from the kite to the the max and the other has been pushed out towards the kite to the max The change in line length during this maneuver is exactly 25cm for each side This tells us that the maximum change in line length needed to control the kite is 25cm Therefore the length L for our slider design must have a minimum of 25cm or roughly 9 9in to sufficiently control the kite The difference in the forces on the slider is the difference in the line tensions doubled To determine the difference in the line tensions during a turn we must understand the dynamics taking place during the kite s flight In figure 35 we see a free body diagram of the kite with the control slider at n
46. ing Input of Error Amplifier Connect FB to a resistive divider between the buck converter output and GND to adjust the output voltage from 0 6V up to 0 85 x IN 8 RT Oscillator Timing Resistor Input Connect a resistor from RT to GND to set the oscillator frequency from 100KHz to 1MHz 9 GND Analog Ground Connect PGND and AGND together at a single point 10 PGND Power Ground Use PGND as a return path for the low side MOSFET gate driver 41 DRV Gate Driver Supply Voltage DRV is internally connected to the low side driver supply Bypass DRV to PGND with 2 2uF minimum ceramic capacitor see the Typical Application Circuits 12 DL Low Side External MOSFET Gate Driver Output DL swings from DRV to PGND Boost Flying Capacitor Connection Internally connected to the high side driver supply Connect a 13 BST ceramic capacitor of at least 100nF between BST and LX and a diode between BST and DRV for the high side MOSFET gate driver supply 14 LX Inductor Connection Also serves as a return terminal for the high side MOSFET driver current Connect LX to the switching side of the inductor 15 DH High Side External MOSFET Gate Driver Output DH swings from BST to LX 16 CSP Current Sense Positive Input Connect to the drain of low side MOSFET with Kelvin connection m EP Exposed Pad EP is internally connected to ground Connect EP to a large copper ground plane to maximize thermal performance MAKII MAX15046 40V High Performance Sync
47. ing frequency determine the inductor used set the valley current limit and determine the input and output capacitors 22 anzz AL anzz jnozy 42 a OIE St SH 4 H 44021 ancy 92 62 GUN 10061 1 4 gt De Ov ZE 9H du 4981 01922 440072 anzz cel 99 3 5 oni 6H 0 1 no anol DA alqeu3 converter circuit diagram Figure 15 DC DC step down voltage OM ZE m N Voltage V Current A r Charge Controller Input Simulation Vin V after cap 10 5 Microprocessor Design The microprocessor needs to be chosen based upon what inputs and outputs it needs to have for the current project After the kite system conceptualization ideas of what is needed in a microprocessor are formed The need to monitor the current and voltage to calculate the power is first understood There is also need for an input to measure the length of string released as well as a need for four inputs to measure the kite string angles to determine the kite s relative position in the air Finally a tension sensor input is necessary to be able to scale calculations up or down depending on wind speed All of these inputs require at least 8 A D Inputs A D inputs will also be needed for the three
48. kit strings provided dust rust and drift are considered in the design The total cost for this sensor design is estimated to be between 3 and 5 each and falls under the miscellaneous electronics category in the budget 36 In order to scale the predetermined flight pattern proportional to wind speed a tension sensor was designed Actual wind speed was not sought because the tensions on the line could be used to represent both the wind speeds and serve in testing for the efficiency of the overall system The force sensor selected for our tension sensor shown in figure 30 will be incorporated into an overall design as shown in figures 31 and 32 8 FlexiForce 0 100 Ibs Resistive Force Sensor Kit 0 100 Ibs FlexiForce Force Sensor Phidget Voltage Divider 24 Sensor Cable Price 24 40 1001 Sensor Conductance 1R Resistance K Ohms Figure 30 Force Sensor Kit Force Ibs The tension sensor design shown in figure 32 converts the tension on the string to a force on the FlexiForce sensor FlexiForce Sensor Kite String Hinge Pully Shaft Welded to Hinge Figure 31 Tension Sensor Model The tension on the string can be calculated from the force measured on the FlexiForce sensor as shown in the following equation 37 T A Fs A B sin A Where T is the tension on the string and Fs is the measured force on the sensor The dimensions A B and
49. ky and therefore use more of the energy than a stationary turbine can This technology could allow individuals to become energy self sufficient and it could also be used in large scale projects as wind farms that produce high power Operational Description The kite wind generation unit will produce power based on the drag force produced by the kite in flight and the amount of line pulled which will be connected to a generator over time When the kite has reached its maximum height the kite orientation will be changed to reduce its drag coefficient and the kite will be retracted using much less power than is generated from the pull up The kite will run autonomously in winds of 10 to 45 kilometers per hour When the wind speeds are too high the kite will be retracted to prevent damage to the system If the wind speeds are too low the kite will be retracted The system will also have a user interface that displays the length of line released and power generation The user will also have options for three different modes of operation for the kite deploy sustain and retract Technical Requirements System will initially supply its own power to initiate energy generation and then store excess generated power If power generation is not sufficient to generate excess power the kite will be retracted and the user interface will run off of stored power System will generate at least 500 watt hours DC within 10 hours Kite system will be able to generat
50. l taking place however all parts will be ordered before Christmas break and are expected to arrive by January 11 Final analyses and simulations are being completed for use in the final presentation 48 8v zy 4 Gantt Chart Fall 2009 Second Wind Josh Dowler Caleb Meeks John Snyder ID Task Name Start Date Finish Date FLO 9 8 2009 F2 0 F3 0 9 29 200 1 2 EE Brake System Design i X MI Generator Design F4 1 F4 2 F4 3 F5 0 10 13 200 F6 0 ZAM Microprocessor Interface Design 10 13 2009 11 3 2009 F8 0 F9 0 i Parts Selection F11 0 System Design Project Plan 10 1 2009 10 13 2009 Final Design 11 17 2009 12 8 2009 Documentation 9 8 2009 12 10 2009 A Project Management 9 8 2009 12 10 2009 o ojo t0 to un un lt lt et et 3 3 gt 5 5 TES lt v v Duration Weeks 3 1 5 1 7 1 6 5 1 7 1 4 1 8 12 5 12 5 15 17 125 125 Sep 2009 Oct 2009 Nov 2009 8 15 22 N w N e N 7 e N gt 18919 SUIAISSyUueYL Dec 2009 6 ep anb Gantt Chart Spring 2010 Second Wind Josh Dowler Caleb Meeks John Snyder Duration Jan 2010 Feb 2010 Start Date Finish Date Weeks 11 19 26 2 9 16 23 2 ID Task Name 51 0 SEM Mechanical
51. losses gate charge currents and switching losses increase Inductor Selection Three key inductor parameters must be specified for operation with the MAX15046 inductance value L inductor saturation current ISAT and DC resistance RDC To determine the inductance select the ratio of inductor peak to peak AC current to DC average cur rent LIR first For LIR values that are too high the RMS currents are high and therefore I2R losses are high Use high valued inductors to achieve low LIR values Typically inductor resistance is proportional to induc tance for a given package type which again makes I2R osses high for very low LIR values A good compromise between size and loss is a 30 peak to peak ripple cur rent to average current ratio LIR 0 3 The switching frequency input voltage output voltage and selected LIR determine the inductor value as follows Your Vin Vout Vin x fsw x where VIN VOUT and IOUT are typical values The switching frequency is set by RT see Setting the Switching Frequency section The exact inductor value is not critical and can be adjusted to make trade offs among size cost and efficiency Lower inductor val ues minimize size and cost but also improve transient response and reduce efficiency due to higher peak cur rents On the other hand higher inductance increases efficiency by reducing the RMS current Find a low loss inductor with
52. mance Synchronous Buck Controller ELECTRICAL CHARACTERISTICS continued VIN 24V VEN 5V VGND VPGND OV CIN noted Typical values are at TA 25 C Note 2 UF 4 7yF RRT 49 9 TA TJ 40 C to 125 C unless otherwise PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Sinking VDRV VCC 3 5 25V DL Peak Current CLOAD 10nF Sourcing VDRV 2 Voc 5 25V DH DL Break Before Make Time 10 WE Dead Time SOFT START Soft Start Duration 2048 switehing Cycles Reference Voltage Steps 64 Steps CURRENT LIMIT HICCUP Cycle by Cycle Valley Current VCSP VPGND VLIM 0 3V 30 Limit Threshold Adjustment valley limit mV Range VLim 10 VLIM 3V 300 LIM Reference Current ILIM VLIM 0 3V to TA 25 45 50 55 yA LIM Reference Current 2 Temperature Coefficient 2909 ppm CSP Input Bias Current Vcsp 40V 1 1 UA Number of Consecutive Current Eje Limit Events to Hiccup Hiccup Timeout 4096 switching Cycles em VCSP VPGND Sink limit Vi 1M 20 uem Sink Current Limit RILIM 1 5V 75 mu TA 25 POWER GOOD PGOOD PGOOD Threshold VFB rising 90 94 97 5 PGOOD Threshold Hysteresis VFB falling 2 65 VFB PGOOD Output Low Voltage VPGOOD L IPGOOD 2mA VEN OV 0 4 V PGOOD Output Leakage Current ILEAK_PGOOD VPGOOD 40V VEN 5V VFB 1V 1 1 THERMAL
53. ons begin with the kite control algorithms A little behind schedule the algorithms are still being modeled in a way that is applicable for software development This should be finished by the end of the semester but can be finished during the first week of Christmas break if needed A final decision on the control motor also still needs to be made The limitations in variety voltage current necessities and funds are making this a difficult search but it will be decided and ordered by the end of the fall semester This decision is slightly delaying the design for the motor controller since motor specifications for the control motor are not yet available only assumptions can be made Thankfully the motor controller configuration is simplistic and will be quick and easy to implement less than a week once a motor decision is made This final motor controller design implementation may need to take place over Christmas break but the spring semester will not be delayed More research is also being done in the use of the microprocessor in order to begin programming The microprocessor wasn t received until December 8 2009 so strides toward being able to program are well under way More microprocessor self education and programming will take place over Christmas break and will allow the spring semester to run smoothly from a software standpoint Any delays are only minor design decisions that can be decided before the spring semester Parts selection is stil
54. put volt age equals twice the output voltage VIN 2VOUT 50 IRMS MAX ILOAD MAX 2 For most applications nontantalum capacitors ceramic aluminum polymer or OS CON are preferred at the inputs due to the robust ness of nontantalum capacitors to accommodate high inrush currents of systems being powered from very low impedance sources Additionally two or more smaller value low ESR capacitors should be connected in paral lel to reduce high frequency noise Output Capacitor The key selection parameters for the output capacitor are capacitance value ESR and voltage rating These parameters affect the overall stability output ripple volt age and transient response The output ripple has two components variations in the charge stored in the output capacitor and the voltage drop across the capacitor s ESR caused by the current flowing into and out of the capacitor AVRIPPLE AVESR AVQ MAKII Buck Controller The output voltage ripple as a consequence of the ESR and the output capacitance is AVESR p_p x ESR f x Cour xfsw ns 49 Your fsw x L VIN where is the peak to peak inductor current ripple see the nductor Selection section Use these equa tions for initial capacitor selection Decide on the final values by testing a prototype or an evaluation circuit Check the output capacitor against load transient response requirements The allowable deviation of the outpu
55. rque transferred to the motor varied based upon Table 1 the assumed values for the sprockets so an Excel spreadsheet was used to calculate various possible torque values that could be transferred to the motor based upon the gearing ratio and the speed of the kite pulling out Figure 2 Based upon the calculated torque that could be supplied to the system our system will be able to overcome the torque for a 350 watt motor Many inexpensive brushed motors are available with power outputs around 350 watts One brushless motor was found that had a power output in the range of 350 watts However this motor is not reversible and thus cannot be used as a generator The chosen motor is priced at 47 91 from Monster Scooter Parts shown in table 1 The motor has an 11 tooth sprocket for 825 roller chain The system will need a form of gearing to reach the rated motor speed Model MY1016 Volta g e V 24V 36V 24V 36V 24V 36V 24 36V Rated Power W 200W 250W 300W 350W No load Current 4A 1 5 1 0 1 6 1 2 lt 1 8 1 4 2 0 1 4 No load Speed RPM 3300 3350 3400 3450 Rated Torque N m D TO D 90 1 04 1 22 Rated Speed RPM 2700 2650 2750 2150 Rated Current A amp 10 6 7 1 x13 4 8 9 16 0 10 7 18 7 12 5 Eff 2276 2578 2278 2278 Main Application Small electric cars scooters Table 2 Sprockets and Chains The design of the gearing system began during the generator motor selection phase due to the dependency between the two systems T
56. t 4 2001 06 19 Infineon technologies 1 5 Circuit Description Input Circuit TLE 5205 2 Overview The control inputs consist of TTL CMOS compatible schmitt triggers with hysteresis Buffer amplifiers are driven by this stages Output Stages The output stages consist of a DMOS H bridge Integrated circuits protect the outputs against short circuit to ground and to the supply voltage Positive and negative voltage spikes which occur when switching inductive loads are limited by integrated freewheeling diodes A monitoring circuit for each output transistor detects whether the particular transitor is active and in this case prevents the corresponding source transistor sink transistor from conducting in sink operation source operation Therefore no crossover currents can Occur 1 6 Input Logic Truth Table Functional Truth Table IN1 IN2 OUT1 OUT2 Comments L L H L Motor turns clockwise L H L H Motor turns counterclockwise H L L L Brake both low side transistors turned ON H H 2 Z Open circuit detection Notes for Output Stage Symbol Value L Low side transistor is turned ON High side transistor is turned OFF H High side transistor is turned ON Low side transistor is turned OFF Z High side transistor is turned OFF Low side transistor is turned OFF Data Sheet 5 2001 06 19
57. t voltage during fast load transients determines the capacitor output capacitance ESR and equivalent series inductance ESL The output capacitor supplies the load current during a load step until the controller responds with a higher duty cycle The response time tRESPONSE depends on the closed loop bandwidth of the converter see the Compensation Design section The resistive drop across the ESR of the output capaci tor the voltage drop across the ESL AVESL of the capacitor and the capacitor discharge cause a voltage droop during the load step Use a combination of low ESR tantalum aluminum elec trolytic and ceramic capacitors for improved transient load and voltage ripple performance Nonleaded capac itors and capacitors in parallel help reduce the ESL Keep the maximum output voltage deviation below the tolerable limits of the load Use the following equations to calculate the required ESR ESL and capacitance value during a load step ESR AVESR ISTEP X RESPONSE AVQ Cour AVEsL 8 ISTEP tRESPONSE where ISTEP is the load step tSTEP is the rise time of the load step tRESPONSE is the response time of the control ler and fo is the closed loop crossover frequency 15 9 lt Appendix B PIC18F4550 Microprocessor Appendix C TLE5205 2 Motor Controller e Infineon technologies 5 A H Bridge for DC Motor Applications TLE 5205 2 1
58. tart tha allows prebias startup without discharging the output The digital soft start function employs sink current limiting to prevent the regulator from sinking excessive current when he prebias voltage exceeds the programmed steady state regulation level The digital soft start feature prevents the synchronous rectifier MOSFET and the body diode o he high side MOSFET from experiencing dangerous lev els of current while the regulator is sinking current from the output The MAX15046 shuts down at a 150 junction emperature to prevent damage to the device DC DC PWM Controller The MAX15046 step down controller uses a PWM volt age mode control scheme see the Functional Diagram Control loop compensation is external for providing max imum flexibility in choosing the operating frequency and output LC filter components An internal transconduc tance error amplifier produces an integrated error volt age at COMP that helps to provide higher DC accuracy The voltage at COMP sets the duty cycle using a PWM 10 comparator and a ramp generator On the rising edge of an internal clock the high side n channel MOSFET turns on and remains on until either the appropriate duty cycle or the maximum duty cycle is reached During the on time of the high side MOSFET the inductor cur rent ramps up During the second half of the switching cycle the high side MOSFET turns off and the low side n channel MOSFET turns on The inductor releases
59. teration to find a k and spring extension AX that could be manufactured and purchased The springs found for minimum and average winds happened to be able to use the same radius RO that is defined in Figure 5 as 1009 in k Ibf in RO the variable diameter spools for spring return Se 15 87 2 00 5 99 1414 0 38 mechanism The spring found for the 1587 200 3 37 18 85 0 50 maximum wind speed required a smaller RO to 15 87 200 2 16 23 56 0 63 allow for the necessary six feet as seen on the motor and gearing calculations page The use of a linear spring was determined by the wide variety of linear springs over torsion springs on the market Furthermore linear springs generally have a smaller k value which will Fmax 16 R3 in k Ibf in in RO 50 58 200 4293 9 42 0 25 50 58 200 2580 1216 0 32 requirements during oscillation 50 58 200 1720 1489 0 40 allow the kite to meet its displacement The springs being used by this system are from W B Jones Spring Company Inc W B Jones offers quick and easy purchase of a number of stock linear springs Table 6 shows the specifications for the three springs chosen for minimum average and maximum wind speed Table 5 Wire Free Part ia Dia Lenath No Rate Load in in Ibs in Ibs values Fmin 0 875 0 062 8500 137 034 617 Favg Fmax 1 250 0162 12 000 346 1250 6245 Table 6
60. tive dead time circuit monitors the DH and DL outputs and prevents the opposite side MOSFET from turning on until the MOSFET is fully off Thus the circuit allows the high side driver to turn on only when the DL gate driver has turned off preventing the low side DL from turning on until the DH gate driver has turned off The adaptive driver dead time allows operation without shoot through with a wide range of MOSFETs minimiz ing delays and maintaining efficiency There must be a low resistance low inductance path from DL and DH to the MOSFET gates for the adaptive dead time circuits MAKI 40V High Performance Synchronous 15046 stops both DL and DH drivers and waits for 4096 switching cycles hiccup timeout delay before attempting a new soft start sequence The hiccup mode protection remains active during the soft start time Undervoltage Lockout The MAX15046 provides an internal undervoltage lock out UVLO circuit to monitor the voltage on Vcc The UVLO circuit prevents the MAX15046 from operating when Vcc is lower than VUVLO The UVLO threshold is with 400mV hysteresis to prevent chattering on the rising falling edge of the supply voltage DL and DH stay low to inhibit switching when the device is in undervolt age lockout Thermal Overload Protection Thermal overload protection limits total power dissipa tion in the MAX15046 When the junction temperature of the device exceeds 150 C an on chip thermal
61. tor at the supply voltage is the only external circuitry due to the integrated freewheeling diodes Data Sheet 1 2001 06 19 technologies Overview 1 2 Pin Configuration top view TLE 5205 2 TLE 5205 2GP OUT1 IN2 0 2 01990 5205 26 OUTI IN IN OUT2 EF GND Vg 01991 01680 5205 25 02513 Figure 1 Data Sheet 2001 06 19 technologies Overview 1 3 Pin Definitions and Functions Pin No Pin No Symbol Function P TO220 P DSO 1 7 OUT1 Output of Channel 1 Short circuit protected integrated freewheeling diodes for inductive loads 2 8 EF Error Flag TTL CMOS compatible output for error detection open drain 3 9 IN1 Control Input 1 TTL CMOS compatible 4 1 10 GND Ground 11 20 internally connected to tab 5 12 IN2 Control Input 2 TTL CMOS compatible 6 15 Vs Supply Voltage block to GND 14 OUT2 Output of Channel 2 Short circuit protected integrated freewheeling diodes for inductive loads 2 3 4 5 Not Connected 16 17 18 19 Data Sheet 3 2001 06 19 07 Infineon TLE 5205 2 technologies Overview 1 4 Functional Block Diagram Error Flag OUT1 IN1 UT2 IN2 2 Diagnosis and Protection Circuit 2 02394 Figure2 Block Diagram Data Shee
62. ty of air at 1 2kg m and V is the wind speed A B G Independent Variables Voltage to Motor V A a String Lenth ft m 80 27 43 Retraction Time min AAA s Dependent Variables 7 Design Radius of Spool in cm 8 Ampsto Motor 02185 00 9 Whr output to reel 12 02 0111 11 rate line in ft min m min 12 rate spool spin rev min 265800 13 length per revolution ft cm 14 torque needed Ib in N cm Table 12 Excel spreadsheet screen shot O gt HP The equations used to calculate the values table 12 are as listed below Rate line in string length retraction time Rate spool spin Voltage to Motor 443rpm V from CIM motor specks Length per revolution Rate line in Rate spool spin Design Radius of Spool sqrt Length per revolution pi 12 Torque Needed Design Radius of Spool 7 Ib Amps to Motor Torque needed 0 16124 Ib in A from CIM motor specks These values were then converted to metric units as well The retraction time value was set to five minutes instead of the required ten minutes in order to design for a factor of safety of two Using this spreadsheet a motor was found that met the specified requirements The specific motor selected is shown in figure 43 and the resulting system using this motor is shown in figure 44 It can be calculated that at most about 12 77 watt hours is required to deploy and retract the kite Whiotal Whgeploy 6v 2 7A
63. using current and voltage measurements using a multimeter Implementation Consideration Follow FAA regulations part 101 subparts A and B no flight between sunset and sunrise a letter of intent to fly the kite above 150 feet sent to the nearest FAA ATC facility a 100m radius of land without obstruction around base set in an area five miles away from an airport land must have ground visibility greater than 3 miles and the kite line must have streamers at 50 foot intervals above 150 feet that are visible for one mile The leads for the generator and battery will be covered to prevent shock Sprockets and chains are part of the design and could propose some safety issues Final Design Block Diagram Generator Tension Min 10 N p 7A max 14A min 2A Max 250N Charge Controller String User Movement Interface Line Length Kite Tension Dynamics 5VDC Power Micro 12V 200mA Control 0 12VDC Power Processor Supply String Displacement Max 4m Min 0m 5VDC amp 12VDC 2A Tension Min 10 N Max 250N Motor dem Controller Controls Organization and Management John Snyder John is a senior computer engineering student with 50 50 electrical and engineering and computer science split He will be working with programming the microprocessor to get it to work with the motor controller kite controls system and the user interface He will also be
64. way user mode switch on the user interface This switch allows the user to let the kite ascend retract or sustain The other portion of the user interface is the LCD screen which will output the length of line released and the instantaneous power generation measured The LCD screen will require five I O ports on the microprocessor The last feature the microprocessor needs is a pulse width modulation system to control the two motors Another important consideration taken with the microprocessor is time Development time is a significant factor in building the electrical system This led to the need for a development board A development board allows the programmer to easily write software for the microprocessor and upload it without having the hassle of a using a microchip programmer and designing a PCB board for the microprocessor The only downfall is the expense that arises with development boards If a single microprocessor was purchased it would cost 4 6 The development board cost close to 50 This cost was worth the time that would have been lost if a standalone microprocessor was purchased To view the trade off decision matrix for microprocessor selection see table 8 All of these considerations led to the Microchip 18 4550 Development Board from Futerlec com This is development board within budget that meets all the criteria needed for inputs and outputs and it even allocates some extra features All of the sensors will have to
65. wer Generation System Diagram Cont 17 Power Generation System Diagram Cont 18 Power Generation System Diagram Cont 19 Charge Controller Design Development of a proper charge controller for our application required the consideration of many different factors This begins with the motor that is generating our power We have a 24V 350W DC motor as our generator This means the charge controller needs to be able to handle high voltage up to 24V and high current inputs up to 14A It then needs to regulate those high inputs into a manageable power source to charge a battery The battery chosen is a 12V 26Ah lead acid battery This battery will allow a capacity of 312 watt hours The entire system needs to prove it can generate 500 watt hours within a ten hour period Since storing all of this energy to the battery is not possible the current and voltage generated will be monitored over that time to compute the average energy production Since constant current and voltage generation measurements need to be taken to output the instantaneous power generation to an LCD screen sensors that were rated to handle a high power input needed to be acquired Some possible sensors looked into were current monitor ICs using high side current shunt and a simple Hall Effect current sensor uses the electrical fields produced by the current to produce potential Most current monitor ICs are rated for very low currents therefore they were
66. working on the charge controller to prevent it from overcharging and surge protection for the power supply He will also be working with different sensors to provide information for the system Josh Dowler Josh is a senior mechanical engineering student and is the project leader He will be in charge of converting the tension provided by the kite behavior and turning it into electric power He will be working with the generator motor and a freewheel mechanism to allow the kite to retract without affecting the generator and selecting gear ratios as necessary As project leader he will be in charge of managing the budget overseeing all project happenings and reviewing documentation Caleb Meeks Caleb is a senior mechanical engineering student He will be in charge of working with the controls system and kite behavior He will construct and work closely with John on the electrical and mechanical aspects of the controls system The controls system will also link with the power generation processes and therefore Caleb and Josh will be working to integrate their systems All team members will contribute equally to any documentation that will be presented including reports and oral presentations Each team member will be in charge of maintaining their notebooks and doing research on their respective parts outside of group meeting times Team members are required to attend team meetings unless they notify the other team members about their absence

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