The Tohoku Relief Project Group 15 Keith Walls - EE Imran Ali - CpE Travis Comer - EE WCF Funded Mentor – Marcus Ledet
List of Sponsors Workforce Central Florida Monetary Funding Of The Project S&C Electric Company Advising And Quality Check Petra Solar Donated Solar Panels C&S Companies Advising And Printing Progress Energy Invitation To Symposium
Motivation Rolling blackouts were a big problem for Japanese universities after the 2011 Tsunami Waseda University, in Shinjuku, Tokyo reached out to the UCF IEEE chapter to design a green power generation system to power the basic classroom essentials when a blackout occurred.
Tohoku Region
Goals and Objectives Simultaneous solar and wind power generation AC and DC power output Off-Grid laptop and projector power High efficiency Portable/semi-modular design System status and performance screen
Output Power Specifications 120VAC at 60Hz Supplied through typical home receptacle 12VDC Supplied through typical automotive cigarette lighter receptacle 5VDC Supplied through USB connection
Power Storage Specifications Estimate the max draw of a laptop and a projector at 600W Battery capacity of at least 25Ah is necessary Simple charge cycle implementation Safe Large cycle life
Input Power Specifications Recharge the battery in less than 2 hours using simultaneously generated solar and wind energy Average of 100W solar energy Average of 200W wind energy
Overall Block Diagram Power Generation: Travis Power Storage: Keith Power System Monitoring: Imran
Design Concept
Solar Panels Make/Model - BP SX3200 Cell type - Multicrystaline Max power output – 200W Max power voltage – 24.5V Max power Current – 8.16A Donated
Wind Turbine Sunforce 45444 Cut-in wind speed – 4.5MPH Max power output – 450W Max Power Voltage – 15V Max Power Current – 30A
Average Power Output Average Tohoku Region Wind Speed: 15 kmh ≈ 9 mph Average Wind Power Output ≈ 200W
Battery Chemistries Lead acid vs. Lithium ion vs. Nickel-metal hydride NiMH batteries have a complex charging cycle Li-ion batteries have safety concerns and are expensive The Lead acid battery was chosen due to it’s simple charging cycle, safety, and low cost
Battery Construction AGM vs. Gel Cell vs. Flooded cell Electrolyte evaporates easily and can be spilled in flooded cell batteries Gel cell batteries usually have a higher cost and internal resistance, but a higher cycle life than comparable AGM batteries The AGM battery was chosen due to it’s durability, lower internal resistance, and lower cost
Battery Comparison Battery` Capacity (Ah) Weight (lbs) Price UPG UB12550 55 38.5 $199.00 Optima D51 38 26 $158.07 Concord PVX340-T 34 25 $177.00 Data Safe NPX-150R 40 34.2 $161.99
Inverter Pure sine wave vs. modified sine wave. Pure sine wave needed for grid tie applications and use with sensitive equipment Similar efficiencies (~90%) Pure sine wave inverters often cost more than 3 times that of a comparable modified sine wave inverter The modified sine wave inverter was chosen due to the lack of benefits of a pure sine wave inverter for our application
Inverter Comparison Temperature Short Circuit Low Battery Protection Protection Protection Protection Efficiency Soft Start Overload USB Port Price ($) Rating Power Peak Vector VEC043B 750 90 X X X X X 64.99 Wagan 2016-6 700 90 X X X X X 60.15 Pyle PINV3 800 90 X X X 44.99 Power Bright PW900 900 90 X X X X 64.44
Inverter Connections
Electronics Enclosure Contain the battery, charge controllers, sensors, microcontroller, and display Externally accessible power outlets Approximate 11” x 24” x 24” external dimensions
Necessary Solar Charge Controller Features Maximum Power Point Tracking (MPPT) to maximize efficiency Charge cycle compatible with 12V lead- acid batteries Sleep mode for night time hours
Solar Charge Controller IC Comparison TI SM72442 Perturb and observe MPPT method Requires interfacing with an H bridge driver through four PWM gate drive signals which will then control the MOSFETs in a buck/boost converter TI BQ24650 Constant Voltage MPPT method Directly controls buck converter to regulate the charge voltage
MPPT Method Comparison Perturb and observe Measures voltage and calculates dp/dv If the slope is positive, the algorithm knows it adjusted in the correct direction. If the slope is negative, the algorithm knows it adjusted too far and needs to go back.
MPPT Method Comparison Constant voltage Drawing current from PV panels causes panel voltage to drop The algorithm constantly adjusts the charging current to keep the panel voltage at the max power point voltage, which has a linear relationship to the panel’s easily measured open circuit voltage
Solar Charge Controller TI BQ24650 was chosen Simpler implementation – only one IC Has capability to implement PV panel temp at a later time Evaluation board available
Solar Charge Controller Schematic
Charge Controller Connection
Microcontroller Monitor Power Usage Monitor Power Generation Monitor Battery Voltage Display all data on a easy to read screen
Microcontroller ADC’s needed 2 current sensors 1 battery voltage 1 GPIO for screen (serial connection) Low power usage At least 1KB memory
Microcontroller Comparison MSP430G2231 ATmega2560 Operating Voltage 1.8 Volts 5 Volts Flash Memory 2 KB 256 KB ADC 8 16 GPIO 10 54 Price Free $59.95 MSP430G2231 Chosen
Functions Functions Description Void getValues() Get values from ADC which will be converted into its appropriate real time values Void Buttonpressed() Determines which option to send to the display when the button is pressed Void Transmit() Main Transmit function which calls TXString(char* string) or InttoDisplay(int number) Void InttoDisplay(int number) Transmits number over serial to display Void TXString(char* string) Transmits String over serial to display
Display Functional/ Easy to use display Button will toggle through options Display will be updated upon button being pressed.
Display Comparison Sparkfun SerLCD uLCD-144(SGC) 16 x 2 Voltage 5 Volts 3.2 Volts User Experience Simple Display Complex Display Outdoor Environment Easier to read Light intensity can affect display Price $29.99 $55.99
Voltage Regulators Using linear regulators UA78M33 & UA7805 Planning to change these to switching regulators for max efficiency Total of 3 regulators used 5V regulator for LCD 5V regulator for current sensor 3.3V regulator for microcontroller
Current Sensing Measure the current going into and out of the system for power calculations Must be able to handle a maximum of 60 amps Must have high sensitivity for accurate calculations
ACS758xCB Vs. CS100A ACS758xCB CS100A Peak Current 100 A 100 A Current Direction Unidirectional Bidirectional Current Sensitivity 40 mV/A 20 mV/A Ease of Use Need to be mounted Already on a PCB with 4 oz Copper Input Voltage 3-5.5 V 3-5.5 V Price $7.00 $14.99
Power Monitor Schematic
Power Monitor PCB Layout
3D View of Power Monitor PCB
Power Connection Schematic
Budget Part Budgeted Price Amount Spent Solar Cells Donated Donated Wind Turbine $850.00 $729.44 Battery $160.00 $137.99 LCD Screen $30.00 $28.68 MSP430 $10.00 $0.00 Current Sensors $100.00 $92.57 PCB's $150.00 $70.80 Enclosure $150.00 $112.68 Charge Controllers $90.00 $429.08 Mirrors $70.00 $0.00 AC - DC Converter $80.00 $70.43 Telescoping Tripod Stand $130.00 $113.35 Miscellaneous Hardware $100.00 $20.00 Total $1,920.00 $1,805.02 $114.98 Remaining
Distribution of Work
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