SOLAR array MONITOR

(s.a.M)

GROUP 14WILL ADROBEL

MOHAMMED JEBARISTEPHEN R. PARKER

MIKE TELLADIRA

Sponsored by QuickBeam Energy

Motivation

Growing demand for all solar power devices Increasingly larger arraysGovernment tax credit

Closer monitoring neededTroubleshooting is laboriousLots of money lost due to bad panels.

Government programs require documentation

Specifications

Monitoring capacity 6 strings of solar panels

Cost $5 per solar panel. Frequency of reporting <15 minutes

SPECIFICATIONS (CONT.)

Physical size 5"x 2"x10“

Transmission wireless or direct wire

Power source the solar array.

Lifetime 15 to 20 years.

S.A.M, Block Diagram

CURRENT SENSOR

Mohammed Jebari

Current sensor spec.

Low power consumption Resist to temperature variation Handle a voltage up to 500V Short response time Easy to install Very cheap

ComparisonCSLT6B100 CSA-1V Asahi EQ-710L

Supply voltage

4.5V ~ 10.5V 4.5V ~ 5.5V 3V ~ 5.5V

Supply current

9mA 11-16mA 9-12mA

temperature -25 to +100 °C -40 to +125°C -30 to +100°C

Response time

3µs 6µs 3-5µs

price $6.55 $4.95 $3.27

CSA-1V sentron Basic electrical connection diagram

Pins 4, 6 & 7 are used for factory programming.

Pins 4 & 7 should be terminated to VDD (Pin 2)

Pin 6 should be terminated to GND (Pin 5)

Single ended output config.

differential output config.

Needs differential output configuration for S.A.M

Current Measurement CSA-1V differential

output voltage for a circular conductor (wire) located on top of the IC can be approximated with the equation:

d = distance (mm) from chip surface to center of wire

I = Current in conductor

)3.0(

*060.0

mmd

Ivoutdiff

Interface circuits

Differential to single ended, 0-5V swing for DC current.

Output level be no more than 2.5 +/- 2.0 volts to prevent electrical saturation and non-linearity

vv outdiffout*2

Accuracy considerations

The absolute accuracy of the current measurement depends on several factors which are:

Distance between the conductor and sensor The closest the conductor to the sensor, the highest

the accuracy will be

Stray fields The sensor is an open filed magnetic sensor therefore

it can sense fields from other sources

Acc. considerations (CONT.) The conductor position should be the same for each part in a production run.

The conductor should form right angle will minimize any pickup from adjacent conductors.

The higher the current and closeness of the conductor to the IC, the more accurate the reading will be.

Acc. considerations (CONT.)

Sensitivity variation The variation in magnetic sensitivity of the

CSA-1V is +/- 3%.

DC Offset voltageSpecified to +/-15mV max

TemperatureTemperature changes affect magnetic

sensitivity and DC offset voltage

Temp. affects on offset volt.

DC offset voltage changes as temperature varies

Offset drift change is between -0.2 and 0.2 (mV/°C)

Add temp. sensor Off. drift = K*∆T

Temperature sensor

Analog temperature sensor 3V to 5.5V, 90µA Measure temp. −40° to +230°F±1.0°F accuracy (at +77°F) < ±2.0°F Output of 10mV per degree F Price $ 2.51

LM34 DS18B20

1-Wire digital thermometer 3V to 5.5V, 90µA Measure temp. -67°F to +257°F ±33°F Accuracy 14°F to +185°C Can Be Powered from Data Line Price $4.25

LM34 Temp. sensor

LM34 is an analog temperature sensor, its voltage output can be affected by noise.

Add 0.1 µF capacitor between the power and the ground pin. Reduce the effects of noise picked up on

the Signal line. Improve the stability of the measurement.

Voltage divider Low current

drain

Low power consumption

less than 0.155 mW

Voltage divider ratio 100:1

Voltage divider (cont.)

Stephen R. Parker

MICROCONTROLLER

micro. requirement

Bits of precision in the AD measurements:12 bits yields 212 – 1 = 4095 increments

Max 600 volts / 4095 = .147 volts of discrimination 10 bits yields 210 –1 = 1023600 / 1023 = .59 volts of discrimination

Number of A/D pins:6 input lines x 2 measurements = 12

Desirability of integrating stages into one chip: Nice but $$ Price: Powerful microcontrollers for less than $10

Micro. requirement (cont.)

Power requirements: drawing from UNLIMITED power source

Operating temperature: Must endure 40°C to 85°C

Connectivity: USART

Software programmable: C language compiler available

Case: DIP (dual inline packaging) for using on a breadboard

Criteria

PIC18F4458-I/P

Silicon Laboratorie

s C8051F542-

IM

Analog Devices ADUC7026BSTZ6

2

Microchip Technology

PIC24HJ128GP204-E/PT

Temp -40°C ~ 85°C

-40°C ~ 125°C -40°C ~ 125°C -40°C ~ 125°C

#AD inputs

12 18 12 12

#prec. bits

12 12 12 12

Connect. USART USART USART USART

Compiler available

“C compiler optimized architectur

e

C compilers “available”

No mention of C compiler

compatibility

“C compiler optimized

instruction set”

Case 40 pin DIP surface mount

40 pinsurface mount

40 pin surface mount

Dev. kit $60(200) $99 $86 $130

Micro. alternatives

Processor PIC18 F 4458

Memory 8 bit , 2K x 8 RAM Program memory FLASH Speed 48 MHz Connectivity USART module, USB A/D channels 13 pins A/D bits 12 Power 4.5 - 5.5 volts Power dissipation absolute maximum 1 W Packaging 40 pin DIP Operating temp. -40°C to 85°C

Micro. circuit connections

Software Flow Chart

The AD registers ADCON0

Bit 0 enables the ADC Bit 1 status bit Bits 2-5 selects the AD channel Bits 6,7unused, read as zero

ADCON1 Bits 0-3 configures whether the ports are AD or DA Bit 4 selects AN3 as Vref+*

Bit 5 selects AN2 as Vref- Bits 6,7unused, read as zero

ADCON2 Bits 0-2 selects what to use as the “conversion” clock Bit 3-5 selects data acquisition time Bit 6 unused, read as zero Bits 7selects right or left justification

ADRESH and ADRESL When the A/D conversion is complete the result is stored there, the status

bit of the ADCON0 register is cleared and the A/D Interrupt Flag bit is set

TRANSMISSION William Adrovel

Transmission SENSOR DATA COLLECTION

1 A/D Sample from sensor = 12 bits XXXXXXXX XXXX

1 Sample will require 2 Bytes for storage XXXXXXXX XXXX0000

We will sample 10 Channels every second 20 bytes of data/second

Data will be stored on 2KB of RAM until transmission

Actual data available for storage will be determined after all programming is finished.

Transmission (cont.) Efficiency

Transmitting requires more power from our system.

Transmit as little as possible but still be frequent enough to provide constant up to the minute readings from the solar array.

Use onboard RAM to store data until time to transmit

1.5 KBytes is approximately 75 * 20Bytes Transmission every 75 seconds

UART for Serial Transmission

Transmission (cont.) What will a S.A.M. Packet look like?

1Packet: Start = 2 Bytes 10 Channels = 20 Bytes Checksum = 1 Byte Total = 23 Bytes

75 Packets*23 = 1725 Bytes /Transmission

Bandwidth needed to transmit our data will be very little.

Transmission (cont.) METHODS OF TRANSMISSION

WiredDB9 Serial Connection

Simplest and lowest cost Winter Haven will have this solution

Ethernet Controller Pros: Direct connection to QuickBeam

WirelessXBEE 415 MHz RF Transmitter and Receiver

Transmission (cont.) Types of QuickBeam Projects

Commecial Office Building

Winter Haven: DB9 Connection Ethernet

Distributed Solar Arrays Wireless

Residential Wired : DB9 or Ethernet Connection

Transmission (cont.)DB9 Serial Ethernet XBee RF

-DB9 Connector - 1.95-Max232 - $1.95

ENC28J60 - $34.95 XBee2 x $22.95= $45.90

RF Transmitter - $3.95RF Receiver - $5.95

-57600 baud -10BaseT -LOS Range: 300ft (100m)-250Kbps

-434 MHz Transmitter Operation -LOS Range: 500ft (~150m)-2400 or 4800 bps

Pros:-Simplest-Cheapest

Pros:-Has direct connection to QuickBeam

Pros:-Mesh Network support-Simple to operate

Pros:-Very low cost-Simple to operate-Good Range

Cons: Cons:-Higher Cost-More complicated circuit design

Cons:-Higher Cost

Cons:-No mesh networking support-Need a new Circuit for the Receiver

Mike Telladira

POWER SUPPLY

Distributed 5V dc Power System

6 Hall effect sensors: 5Vdc at 9mA each = 54mAMicroprocessor: 5Vdc at 90mA = 90mARS 232 chip: 5Vdc < 1mA = 01mA

_____________________________

Total 145mA

Hybrid Power System

3.3Vdc Buck Key Criteria: 90% efficient Has an Enable pin

Choosing a regulator

Choosing a regulator

Choosing the Buck Regulator

LM 22675-5.016V to 40VMore currentBut: 1. Greater support from

Webench 2. Gerber file -Yes 3. Evaluation PCB -Yes

LM 500840V to 100V Less currentBut: 1. Circuit documentation only 2. Gerber file -No 3. Evaluation PCB -No

5V dc Buck Regulator Circuit

Inductor

LM22675-5 chip

Diode

Why use the Evaluation PCB

Inductor

LM22675-5 Cinx Diode

Step down methods2. Transformer

1. Voltage Divider

3. In Series

.75w / (eff% * 16V) = 58.9mA

Transformer issues:1. Interlacing2. Interweaving

Possibility of Series Resistor

Resistor In V Supply I Supply V Buck V R In1R 153Ω 44.5V 21mA 41.7V 3.2V2R 309Ω 44.0V 22mA 37.0V 7.0V3R 470Ω 39.3V 74mA 5.93V 34.4V3R 470Ω 53.1V 21mA 43.7V 9.6V1R 153Ω 53.3V 20mA 50.4V 3.0V

Conclusion: it may be possible to put the buck regulator in series with an input resistor

PERCENTAGE COMPLETED

910 10

9 9.5

43 2.5

1

2.6

9.5 9 910

9.4

Research and De-sign

Test

Purchase

Overall Percentage 71.5%

Project Milestones

March 1 All parts acquired March 3

Power supply finishedSensor circuit finishedMicrocontroller circuit finished

March 7

Final assemblySoftware finished

March 15Software loadedFirst test of prototype

April 1Working prototype

QUESTIONS