Group 5

Alec Calhoun, Patrick Neely,

Eric Eiermann, Brett Burleigh

• Let’s Make Green Power More Practical– Hurricane / Natural Disasters

– Emergency Power

– Portable Power / Remote Power

• Ultimately:– Ease of Use to bring Green Power to the masses!

• Flexibility and Portability

• Familiarity

• Efficiency and Safety

• Flexibility– Multiple Input Types, Multiple Output Types– Inputs are interchangeable

– Solar– Wind– Generator to Harness Human Power

– Portability for Remote Power applications• Use outside of the home, such as on an RV

– Storable in a closet

• Familiarity– Common interfaces that the public has seen before

– Easy to use:• Operate the Display

– Press to Toggle

• Display the Green Box’s performance data

• Efficiency and Safety– Harness as much power generated as possible– Cut back on waste on electronics not being used– Circuit Breakers, relays, and manual switches

• Prevents damage to the system and loads

• Protect user

– Microcontroller to control fan and buzzer:• Fan will automatically turn on

• Buzzer will alert user of high temperature levels

• Store a total of 100Ah that may come from 1, 2, or 3 12V DC power generation devices at any one time

• 12V DC, 15A output receptacle• 5V DC, 500mA USB output receptacle• 110V AC, 60Hz, 9A output receptacle• 24” wide x 24” long x 22.5” high• Approximately 125 lbs • Wheels for ease of portability

– Inputs

– Charging

– Energy Storage

– Outputs

– System Controls

– System Monitoring

• Solar, Wind, Human Power and others

– User selects desired method(s) of power generation

– Adaptable for Various locations, climates, and seasons

• 3 Inputs chosen are for Demonstration and Testing purposes only– Any inputs which meet requirements can be used

• Any DC input that is above the battery voltage– Efficiency reduced above highest bulk charge voltage

• 35 continuous amps per input• If AC inputs are desired, the user must externally

convert power into DC by:– Using a full wave rectifier and large capacitor

Model: SUN-100 (M)

• Specifications:– Monocrystalline Silicon– Size (L x W x D):

42-1/2” x 31-3/8” x 1-3/8”– Weight: 30 lbs.– Cost: $2.78 per Watt

• Electrical

Characteristics

• Voc: 23.60 Volts• Isc: 6.30 Amps• Vmp: 18.10 Volts• Imp: 5.53 Amps

Southwest Windpower Air-X Turbine• Specifications

– Size (L x W x H): 27” x 15” x 9”

– Weight: 17 lbs.

– Durability: 110 mph survival wind speed

– Blades can be removed for easy transport

• Electrical Characteristics• Cut in Windspeed = 8 mph• Observed current with electric drill = 5.8 Amps

AMETEK PMDC Motor• Specifications:

– Low RPM for desired voltage– Weight: 7 lbs.– Cost: $170– Electrical Characteristics:– Rated for 38 V at 1100 rpm

• 14.5 V at approximately 420 rpm

Human Power Mechanism• Fabricated from an old bicycle and motorcycle chain• Final Gear Ratio: 3.25:1• Observed Current: 5.2 Amps (Max), 2.1 Amps (Average)

• Charging one battery with 3 inputs of different voltages presents a problem– Input with highest voltage = only contributor to charging– If blocking diodes are not installed, inputs can destroy each

other

• Two options are possible– Voltage regulate each input to 14.5V, and then combine together

into one large charge controller– Use three separate small charge controllers

• Why 3 charge controllers is the best option:– Voltage regulation built into each controller– Pre-designed and tested allowing for easy integration– Same price as building 3 voltage regulators and using

a large charge controller– Failure of one controller will still allow 2/3 to operate– Most common setup in hybrid systems

• There were two types of charge controllers considered– Maximum Power Point Tracking– 3 Stage Pulse Width Modulation

• MPPT C.C.’s use transformers to turn high voltage, low current into a lower target voltage with increased current– Boosts efficiency greatly when input’s voltage is well above

battery voltage

• 3 stage C.C.’s use PWM to match the desired voltage– All power above desired voltage level is wasted

• Although MPPT has excellent efficiency (above 92%) The extra cost was not a good value.

• 3 Stage Charge Controllers were chosen because:– Cost 40% as much as comparable MPPT C.C.– The user can buy more generators (solar panels or wind

turbines) with the money saved– The cheaper 3 Stage CC has the same efficiency as MPPT CC

when input voltage is close to target voltage

• Model: Xantrex C-35– Voltage: 12V or 24V– Current Rating: 35 amps – Weight: 2.5 Pounds– Size: 8 x 5 x 2 Inches– Cost: $85 Each

-Features:• Microprocessor Control• Pulse Width Modulation•3 Stage Charging• AGM Compatible

• Energy Storage Requirements– Store all the energy generated in a single day

• Full Charge & Discharge Cycle = Maximum Efficiency

– Able to be charged quickly• To harness all available power

– Need to calculate the size of battery• Reduce cost

• Increase life of battery

• 3 Types of Lead Acid Batteries– Starting

• Large Current, but only for Short Duration• Would only last 30 days in our application

– Marine• Thicker Plates• Durable, but still inferior

– Deep Cycle• Thickest Plates • Most durable of all Lead Acid Batteries

• 3 Types of Deep Cycle Batteries- Flooded, “Wet”

• Battery Acid / Fumes can escape into consumers home• Cannot be shipped UPS, USPS, and others

- Gel Cell• Heaviest• Most Expensive

- Absorbed Glass Mat• Fast Recharge• Will not spill acid, even if cracked• Slow Self-Discharge Rate • Most popular Choice in Alternative Energy

• Werker 100Amp Hour – Absorbed Glass Mat, Deep Cycle– Voltage: 12 Volts– Rating: 100 AmpHours– Dimensions:

14 x 10 x 8 inches– Weight: 74 Pounds– Cost (New): $280

• From Inverter:– 110 Volt, 60 Hz AC, 9 Amps (Max) – 12 Volt DC, 15 Amps (Max)

• From Microcontroller:– 5V DC USB Connector, 500mA (Max)

• Three types of Inverters considered– Square Wave

• Inefficient• High Total Harmonic Distortion (THD)• Inductive loads should not be used due to abrupt changes in

the waveform

– Modified Sine Wave• Still inferior due to THD and abrupt changes

– Pure Sine Wave• Produces voltage Identical to household outlet• Any load can be connected• Expensive and Complex Design

• Power Express PE-1000PSW– Continuous Power: 1000 Watts– Surge Power: 2000 Watts– Voltage: 110V +/- 10%– Frequency: +/- 2% 60 Hz– Dimensions: 13.5x9x3.5 in– Cost: $290

– Features:• Low Battery Shutdown (10.5 Volts)• Overload Protection

• Requirements:– Drive LCD Display– Process Digital I/O Devices– Process Analog I/O Devices– Provide All Voltages

Required to Power Devices(12V DC, 8V DC, 5V DC)

• Model: Atmel Atmega168– Chosen Due to Ability to Meet Our

Diverse Needs and C-Programming

– Up to 20MHz speed(we have a 14.75MHz oscillator)

– RISC architecture

– C Programming

– 16 KB Flash (Program) Memory

– 512 Bytes EEPROM (Data Retention) Memory

– 23 Configurable I/O lines

– 6 10-bit Analog-to-Digital Converters(ADC) (0-5V = 0-1023)

• Model: Unitech UC-204– Chosen Due to Compatibility

/Easy Interfacing with Atmel Atmega 168

– 4 Line x 20 Char. Display

– 5V DC Supply

– Integrated Hitachi HD4478U LCD Controller (4-bits data, 2 control lines: Enable and Register Shift)

– C Libraries Available

4 screens of information are toggled through using red pushbutton, which is an input to the microcontroller.

• C Library Simplifies Comm. to LCD Controller• Functions Used:

– void lcd_init(); //enables and configures the display

– void lcd_home();

– void lcd_write_string(const char *x);

– void lcd_line_two();

– void lcd_line_three();

– void lcd_line_four();

– int lcd_putchar(char x, FILE *stream);

//used to create output stream to LCD controller(fprintf)

• Model: Micro Switch CSLA2CDRequirements:– Hall Effect Sensor (varies output voltage

due to changes in magnetic field)– 12V DC Supply(or less)– 0-5V DC Output– Ability to Sense Both AC and DC

CSLA2CD:– 5.4 – 13.2V DC Supply– Output = Vs/2 (+/- .033V per A)– Works for both AC and DC– Using our configuration, max current

possible to sense is 30.30A. (1V/.033V)

• We Supplied Sensors with 8V, therefore it will provide 4V @ 0A

• It changes output at rate of .033V/A.• Our 10-bit ADCs range from 0-1023 at 0-5V• Calculation of 1 step in ADC to Amps:• (0.033V/1A)* (1024 steps/5V) = 6.7584 steps/A• Therefore 1 ADC step = .148A

Challenges:• 1. DC current makes the ADC value increase, while AC

current makes the ADC value oscillate.• 2. “Zero” value must be periodically recalibrated due to

external magnetic fields.

• Functions Used or Developed to Handle Current Sensors:– adc_init(x) //selects the proper ADC – adc_read() //returns raw 0-1023 value from ADC– sampleToAmps(samplecs1, zerovalue) //converts ADC to DC Amps– sampleToAmpsAC(samplecs4, zerovalue) //converts ADC to AC Amps

Auto-Calibration of the Current Sensors:– Each time processor is powered up current sensors are “zeroed” on

first pass of program– Accomplished by taking 200 ADC samples with all current

inputs/outputs unplugged. These 200 samples are averaged and that is set as the “zero” point for that current sensor:

adc_init(1);

// take 200 current samples and average them

temp_avgcs1 = 0.0;

for(ics1=0; ics1<200; ics1++) {

last_samplecs1 = adc_read();

// add this contribution to the average

temp_avgcs1 = temp_avgcs1 + last_samplecs1/200.0;

zero_cs1 = temp_avgcs1; }

• Simple Voltage Divider Circuit:Requirements:– Needed to scale down battery voltage to 0-5VDC for ADC to read it.

Used 4.7kOhm and 15kOhm resistors– Changed 0-20V range to 0-4.77V

• Functions Used or Developed to Handle Battery Voltage:– adc_init(x) //selects the proper ADC – adc_read() //returns raw 0-1023 value from ADC– sampleToVolts(samplebv) //converts ADC to Volts– 100 samples are taken and averaged to stabilize the reading of the

Battery Voltage.

• Model: National Semiconductor LM34Requirements:– 5V DC Supply– 0-5V DC Analog Output

LM34:– 5 – 20V DC Supply– Output = 10.0 mV/degree F– Low Cost / Small TO-92 Package

• Functions Used or Developed to Handle Temperature:– adc_init(x) //selects the proper ADC – adc_read() //returns raw 0-1023 value from ADC– sampleToFahrenheit(sample) //converts ADC to degrees(F)– 100 samples are taken and averaged to stabilize the reading of the

Temperature

• Battery Voltage and Temperature are both displayed on the LCD Display.

• Temperature is also used to control fan and buzzer:– Fan is turned ON when box temperature exceeds 80 degrees. – Fan turns OFF when temperature goes below 79 degrees.– Buzzer is turned ON when box temperature exceeds 84 degrees. – Buzzer turns OFF when temperature goes below 83 degrees.

Challenges:• 1. Algorithm for determining wH.

//handle updating of AC output-to-date:

winst = temp_avgcs4 * 120;//convert A to w(instantaneous)

//add to total kwh output-to-date

//(factor needs to be base on final program scan time)(inital guess is 50ms, .050s)

whsavedtemp = whsavedtemp + (winst * .150 / 3600);.

• $ saved is calculated in real time from wH, using national average cost(12.05c/kwH).

Challenges:• 2. The total wH saved is stored in EEPROM, so it is

preserved during power loss. Taking care to not write to EEPROM on every program cycle, which would be very slow.whsavedtemp = eeprom_read_word((uint16_t*)E_TOTALWHSAVED);

//check to see if update is needed for EEPROM wh counter(every 1 wH):

whcompare = eeprom_read_word((uint16_t*)E_TOTALWHSAVED);

if ((whsavedtemp - whcompare) > 1){

eeprom_write_word((uint16_t*)E_TOTALWHSAVED,whsavedtemp);

}

• Used ExpressPCB software– Designed with Terminal Blocks since most devices

are remote(current sensors, LCD display, fan)– Provisions for laptop connection to do in-circuit

programming

• Used ExpressSCH software– Links to PCB layout in ExpressPCB software to help

detect errors before production

• Five Testing Categories– Input – Charging System– Output & System Performance– Device Protection– Current Sensors

• Testing Equipment Utilized– Fluke Clamp Meter– Craftsman Digital Multimeter– Tektronix Oscilloscope

• Key Objective: verification that all inputs were functional and operated according to manufacturer specifications

• Testing Results:– Solar Panel: Multimeter was used to determine Voc & Isc

• 23.60 volts, 6.30 amps– Human Power Generator: Multimeter was used to verify that the

human power mechanism could drive the generator fast enough to produce a voltage above 12 volts

• Maximum Voc produce was ≈28 volts– Wind Turbine

• Circuitry prevented open circuit testing, therefore the “back of the truck” method was utilized for initial testing

– With battery as load were able to generate a maximum of ≈17 amps at 12 volts

• Subsequent testing was performed using a corded drill to simulate an ≈ 18 mph wind generating 72 watts

• Inputs were later used as testing devices for The Green Box

• Clamp Meter and Multimeter were used to periodically record the battery terminal voltage and current provided by inputs to ensure proper charging process

• Charging Test Results– Inputs used: Solar Panel (constant) and Wind Turbine (intermittent)– 1st 7 hours spent in Bulk Stage– Final hour spent in Absorption Stage

0

2

4

6

8

10

12

14

16

0 0.5 1 2 3 3.5 4 5 6 7 8

Charge Time (hours)

Term

inal

Vol

tage

& In

put C

urre

nt

Terminal Voltage

Current provided by inputs

• Key Objective: Verification that AC output maintains a pure sine wave under various stresses

• Oscilloscope was used to measure frequency and the Vrms waveforms under varying loads

• Initial inverter testing performed while battery voltage was 12.5 volts (> 80% charge)

• Procedure was repeated with battery voltages of 12.1 volts (≈ 50% charge) & 11.7 volts (< 30% charge)

• Testing revealed that inverter, when on, was consuming ≈ 21-30 watts from battery – A relay and switch were installed for convenient inverter

disconnect when not in use

Battery Voltage: 12.6 volts (> 80% charge)

No Load 300 Watt Load

720 Watt Load 720 Watt Load w/ 15 Amps from Inputs

Battery Voltage: 11.7 volts (< 30% charge)

No Load 300 Watt Load

720 Watt Load 720 Watt Load w/ 15 Amps from Inputs

• Key Objective: To ensure device protection components were operating properly

• 40 amp Circuit Breakers– Circuit breaker was installed between battery and inverter– A toaster was used to produce a 720 watt load at the inverter output, leading to a

60 amp demand from the battery– Verification was made that the breaker would “trip” when dc current from the

battery exceeded 40 amps– Testing was repeated for each of the 40 amp circuit breakers

• 100 amp Circuit Breaker– Procedure similar to the procedure for the 40 amp breakers– In addition to the 720 watt load of the toaster, a “light board” was used to provide

an additional 600 watt load• A “light board” is a piece of additional testing equipment designed and built for this

project. It consists of a switch and five lamp holders wired in series allowing for a known, adjustable load.

– Verification was made that the breaker would “trip” when dc current from the battery exceeded 100 amps

• Initial temperature sensor testing was performed at room temperature and accuracy of readout was verified by digital thermometer

• Fan and audible alarm testing was performed after installation in The Green Box– A blow dryer was used to quickly raise the temperature inside of

the box and it was verified that the devices went into operation when the temperature went above the “turn-on” set points, 80°F for the fan and 84°F for the alarm

– The box was then allowed to cool and verification was made that the devices stop operating when the temperature fell below the “turn-off” set points, 83°F for the alarm and 79°F for the fan

• Solar panel was used to create the dc current required for testing the input current sensors– Solar panel created a relatively constant current– Fluke clamp meter was used to measure actual current provided by

solar panel. This value was compared to the readout from the current sensor and the conversion factor was adjusted accordingly

• The “light board” was used in testing the output ac current sensor– This provided a constant, easily adjustable, load– Fluke clamp meter was again used to compare actual current to readout

from the current sensor.• During initial testing, constant fluctuations in the “zero point”

prevented accurate current measurements– It was discovered that the fluctuation of the “zero point” was a result of

small variances in the reference voltage• To solve this problem, a capacitor was placed across the reference voltage

terminal

• Charge Controllers– Max voltage drop through controller of 0.3 volts– Typical operating consumption of 15 mA– ≈ 97% efficient in Bulk and Absorption Stages– Efficiency declines rapidly in Float Stage as battery nears capacity

• Inverter– ≈21-110 watt power consumption through inverter depending on load

• Relay and switch limit loss to times when inverter is in operation– Efficiency varies based on load

• PCB/Fan/Display– Maximum power consumption of 12 watts

• Power transmission losses are negligible• Efficiency of The Green Box

– Will vary based on load• ≈ 83.3% efficient at 200 watts• ≈ 85.0% efficient at 500 watts• ≈ 86.5% efficient at 1000 watts

• Inputs– Solar Panel (monocrystalline construction)

• Capable of converting ≈ 15% of captured sunlight into electricity• Average power generation during testing was ≈ 76 watts• Under these conditions, the total available power to the solar panel in the form of

captured sunlight is ≈ 507 watts– Pavailable=Pgenerated/15%

– Wind Turbine• Average power generation during testing was ≈ 70 watts when simulating an 18 mph

wind speed• At 18 mph, assuming standard temperature and pressure, the amount of power

available to the wind turbine would be 342 watts, an ≈ 20% conversion– Pavaialbe=0.5*ρ*A*V^3

» ρ ≡ air density (≈ 1.225 kg/m^3 @ STP), A ≡ rotor sweep area (m^2), V ≡ velocity of wind (m/s)

– Human Power Generator• Assumption: for every watt-hour produced by the human power generator, the user

expends 4 watt-hours of energy in the form of calories, an ≈ 25% conversion– Total input efficiency: ≈ 17.5%

• Based on 45% of the power for The Green Box being generated by the solar panel, 50% of the power being generated by the wind turbine and 5% of the power being generated by the human power generator

• Overall System Efficiency– From resource to output– Based on 45%/50%/5% solar/wind/human– Will vary based on load

• ≈ 14.2% efficient at 200 watts• ≈ 14.8% efficient at 500 watts• ≈ 15.2% efficient at 1000 watts

• Easy to use Green Energy for average consumer• Interchangeable DC Inputs• 3-stage Controllers that properly charge the AGM

Battery• Inverter with Pure Sinewave 110V 60Hz, AC• Built in 12V Regulator from Inverter• Built in 5V Regulator from PCB (USB)• Microcontroller gives accurate analysis of system

– Displays the Current, Voltage and Temperature– Stores amount of energy and money saved– Fan, and Alarm (Safety Features)

• Portable, compact

• Use Capacitors!• Green Inputs should have been female connections on

the cable, male on the box• Manual resets on the charge controllers.• More than 16K Flash Memory for the Microcontroller.• Measure twice, cut once! Only use level on level surface!