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AMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi Bryce Salmi

AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

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Page 1: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

AMSAT-MPPTDetailed Design Review

Dan CorrieroIan MacKenzieBrent SalmiBryce Salmi

Page 2: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

Customer Needs

Customer Need # Description Comment/Status

CN1 Maximize energy transfer between solar panel and load

Efficiency

CN2 Meet environmental requirements Temperature, Radiation

CN3 Provide limited output voltage Customer supplied upper limit

CN4 Meet mechanical constraints Component size and form factor

CN5 Communicate status information with satellite IHU Health and status information

CN6 Recover from soft errors in software Watchdog, ECC

Page 3: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

Engineering Specifications

Eng. Spec # Description Marginal

ValueIdeal Value Measure

S1 Maximum Power Output >7.24 7.24 Watts

S2 Input Voltage Max >28 28 Voltage

S3 Limited Output Voltage >3.3 4.1 Voltage

S4 MPPT Efficiency* >90% 90.00% Percentage

S5 MPPT Response Time <100 100 Milliseconds

S6 Maximum Operational Temperature >85 85 Celsius

S7 Minimum Operational Temperature <-40 -40 Celsius

S8 TID Radiation Expectation* 30 >30 KiloRad

S9 Component Height Restriction <8.1 5 Millimeter

S10 Layout Area Constraint 144.5 <144.5 Cm^2

S11 IHU Communications NA NA Pass/Fail

Page 4: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

MPPT System Overview

Page 5: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

Constant Voltage MPPT

Adjusting the solar panel voltage to the effective MPPT voltage over panel temperature eliminates a significant source of MPPT tracking error

* Image(s) reproduced from: IEEE:11904425, "A MPPT approach based on temperature measurements applied in PV systems"

Page 6: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

Constant Voltage MPPT

Regulate solar panel voltage Solar cells only provide max power at MPP Voltage Output voltage not "regulated"! Fast "response" and stable

Typically fixed voltage Low tracking efficiency (~80%)

Panel Temp Scaling Increases tracking efficiency drastically! Must know solar cells in use

Page 7: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

This is NOT a "Power Supply"

Regulate the input voltage Output voltage unregulated and can "swing"

from 3.3V-4.1V Limit output voltage if needed during low-load

conditions Will move "away" from maximum power point

Will work without Fox-2 battery MPPT operation does not depend on a battery to

track the maximum power point as many Cubesats pursue

Page 8: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

System Detail Diagram

Page 9: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

MPPT System Layout - Channels

Page 10: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

Detailed Design Overview

Page 11: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

Panel Voltage Control

Page 12: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

System Control

Page 13: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

Radiation Effects

Total Dose Ionization Degrades oxides (MOSFETs)

Threshold Voltage shifts Component parameters degrade Some materials/devices more susceptible Single Event Effects (SEE)

Transients Soft Errors Permanent Damage (Latch Up)

Page 14: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

Radiation Mitigation

Use commercial components that have good radiation test data

Use flight tested components Avoid "vulnerable" circuits and materials

Used good engineering practices Will never be 100% guaranteed

Page 15: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

UC2524A PWM ICFEATURES Complete PWM Power Control Circuitry Uncommitted outputs for Single-Ended or Push-Pull Applications Low Standby Current ... 8 mA Typical Interchangeable with SG1524, SG2524 and SG3524

Page 16: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

UC2524 Radiation Data

This radiation data shows a consistent radiation tolerance

Provides reasonable assurance of radiation tolerance

Similar radiation data found for other components if possible

Page 17: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

Temperature Sensing - RTD

Requirements Provide a voltage based on

panel temperature -60° C to +60° C MPPT accuracy dependent

on temperature accuracy Repeatable measurements

RTD - Benefits Large temperature ranges Very accurate Linear over specification

range

RTD - Drawbacks Positive temperature

coefficient

Page 18: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

Temperature Sensing - RTD

Page 19: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

RTD Driver

Constant current increases linearity and reduces self heating

Page 20: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

RTD - Amplification and Scaling

Please see "Theory of Operation" document for details

Page 21: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

RTD - System Integration

Provides a "scaled" 2.5V reference based on solar panel temperature and is scaled to match the expected Vmpp of the panels at a given temperature.

The DC-DC converter will attempt to "match" this reference with the scaled version of the solar panel voltage, thus achieving maximum power point.

Page 22: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

RTD - Circuit Simulation (100 Ω)

*Vrtd scaled to match max power point panel voltage over temperature.

Page 23: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

RTD - Percent Error

Preliminary Percent error does not include Op-Amp input offset, OP484 exhibits ~165uV MAX

Directly relates to effective tracking accuracy Would prefer any error to be on left side of MPP

Page 24: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

DC-DC (Buck Converter)

Page 25: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

Buck Converter

Two Inputs Solar Panel MOSFET Driver

PWM

Output to OR-ing Function System output is to

payload CCM Operation

Output voltage limit and voltage clamp provides minimum load

Buck converter chosen due to input voltage and output voltage range

Snubber circuits are DNP until board is populated. Transients are layout specific

18V Zener Diode to Protect Vgs

Page 26: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

Buck Converter

Spec Value

VIN,Max 22.62V

VOUT,Max 4.1V

VOUT, Min 3.3V

fSW 300kHz

IL,Max 3A

22.62V is the worst case scenario input in full illumination at -60C

The low output voltage spec comes from the customer. 3.3V is the minimum voltage the payload can operate.

Page 27: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

Buck Converter - Components

*at 300 kHz

Component Selection

Components chosen due to de-rating

Inductor current ripple at 300 kHz = 620 mAOutput voltage ripple at 300 kHz = 20 mV

Page 28: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

Buck Converter - Component Selection Inductor Selection

Selected in order to stay out of saturation (handle max current) Low ESR Current Ripple Switching frequency (as fsw increases, so does L) Inductor-current ratio (LIR) balance: trade-off between current ripple and

response time. Size requirements

Diode Selection Schottky used to reduce losses Low VF Max forward current

MOSFET Selection Low Gate Charge High VGS rating Low RDS,ON

Output Capacitor Selection Low ESR Store enough charge to hold VOUT constant

Input Capacitor Selection Rated for open circuit voltage from panels Low ESR

Page 29: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

MOSFET Driver

Page 30: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

MOSFET Driver

Two Primary Functions: Acts as a level shifter Drives gate of MOSFET with a higher current for faster

transition times.

Page 31: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

MOSFET Driver

Output from the UC2524A was modeled in simulation Proper inversion was derived from app note 2kΩ Resistance was used to model rise and fall times

of UC2524A Speed-up capacitor and diode if need be on output for

faster driving

Page 32: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

MOSFET Driver

Page 33: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

UC2524A - PWM Soft Start

Page 34: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

UC2524A - PWM Soft Start

Slowly allows UC2524A PWM to "Ramp Up" Reduces EMI and is less "harsh" Limits inrush current

Only active during UC2524A power up and remains "out of circuit" otherwise i.e. Solar panels enter sunlight and UC2524 internal Vref powers on

Page 35: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

Output Voltage Limit

Page 36: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

"Soft" Output Voltage Limit

Output voltage limited to 4.1V Reduce PWM duty cycle or completely shut off

Vout scaled and compared to reference (Comparator/OP-AMP) MOSFET "pulls down" input voltage divider

Causes the UC2524A PWM controller to reduce PWM duty cycle (0-95%) Slows down this "reaction" to avoid oscillating PWM action and reduce EMI

Similar to UC2524A shutdown function but exhibits more modulation Basic compensation DNP'ed, further analysis and testing needed

Page 37: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

Output Voltage Clamp

Page 38: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

Output Voltage Clamp

4.3V output from the buck converter causes comparator to turn on the Darlington transistor to dissipate stored charge in the inductor.

Hysteresis may be needed and is DNP'd Compensation DNP components added

Page 39: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

Output Diode "ORing"

Page 40: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

Diode ORing

Allows current to flow only to the payload Does not allow other MPPTs or payload battery to send power the "wrong way" Ideal Diode drastically reduces power loss Schottky diode DNP for testing and backup (Radiation testing failure, etc)

Page 41: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

Output Current Sense

Page 42: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

Output Current Sense

Fixed gain of 100 V/V 3.3V operation

MSP430 3.3V power regulator provides power from battery bus Not dependent on a single solar panel When battery failure occurs it is still powered during sunlight

operation.

Page 43: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

ADC Voltage Scaling & Protection

Resistive divider specific to ADC measurement LC filter is optional

0Ω "jumper" Diodes protect from over-voltage and transients

Page 44: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

Powering the MPPT

Each MPPT regulates its own 5V supply for op-amps and other circuitry

Linear regulators are simple, low noise Low Drop Out - Turns on before UC2524A

Page 45: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

UC2524 Stability

Page 46: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

Star

tup

MPPT Startup and Shutdown

Voltage Device(s) Turning ON

0V OFF (MSP430 always on if BATTERY is good)

6.75V 5V Regulator (RTD Temp, PWM Limit, Voltage Clamp)

8.5V UC2524A

Vout Turn ON MSP430 if BATTERY Failure

Voltage Device(s) Turning OFF

8V UC2524A

Vout Turn OFF MSP430 if BATTERY Failure

6.75V 5V Regulator (RTD Temp, PWM Limit, Voltage Clamp)

0V N/A

Shut

dow

n

Page 47: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

NASA Derating

Source NASA PD-ED-1201

Page 48: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

NASA Derating

Source NASA PD-ED-1201

Page 49: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

NASA Derating - Calculation40V P-CHANNEL ENHANCEMENT MODE MOSFET

NASA Derating of Buck Converter Switch

Derated Limits Operating Conditions

Every component must be checked Tedious but necessary Ensures components experience minimal

stress

Page 50: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

Efficiency

All units in Watts except for power efficiency which is in fractional percent.

Page 51: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

Selected Microcontroller

Texas Instruments MSP430FR5739

Features: 16-Bit RISC Architecture 16KB FRAM Nonvolatile Memory Built in Error Coding and Correction (ECC) 81.4 µA/MHz active current consumption 14-Channel 10-Bit Analog-to-Digital Converter (ADC) with

Internal Reference eUSCI with support for UART, I2C, and SPI 16-Bit Hardware Cyclic Redundancy Checker (CRC) 32-Bit Hardware Multiplier (MPY) Memory Protection Unit (MPU)

Page 52: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

MPPT Health and Status Firmware

Primary functions: Measure analog inputs using an ADC Report measurements to IHU upon request

Secondary function: Take measures to protect firmware integrity from

random memory errors due to radiation events

Page 53: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

Modular Software Structure

All major software functions are separated into modules:

Idea is that each module is relatively generic and independent of every other module, and are all

connected at a single point

I2C Module

ADC10 Module

CRC8 Module

SEU Protection

Module

Page 54: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

Modular Software Structure

Each module consists of three parts:

Target-Specific Functions

Library Functions

InterfaceInterface between module and any code outside of module (e.g. Main)

Functions necessary to carry out module operations, but contain no hardware (target) dependence

Functions and interrupt service routines that are microcontroller (target) specific in nature

Page 55: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

Modular Software Structure

Page 56: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

Communications Message Flow

MPPTMCU

Page 57: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

Communications Message DataField Size

(Bytes) Description

MSG_VER 2 Message control version

SW_BUILD 2 Software build version

BUS_DC_I 2 Output bus DC current

+X_PANEL_V 2 +X solar panel voltage raw value

-X_PANEL_V 2 -X solar panel voltage raw value

+Y_PANEL_V 2 +Y solar panel voltage raw value

-Y_PANEL_V 2 -Y solar panel voltage raw value

+X_PANEL_T 2 +X solar panel temperature raw value

-X_PANEL_T 2 -X solar panel temperature raw value

+Y_PANEL_T 2 +Y solar panel temperature raw value

-Y_PANEL_T 2 -Y solar panel temperature raw value

MPPT_T 2 MPPT microcontroller temperature raw value

CHECKSUM 1 CRC-8-CCITT Message checksum

Page 58: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

MSP430 Support Circuitry

Page 59: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

MSP430 Power - Latchup Protection

Dedicated 3.3V regulator Always powered when battery bus is powered (Battery/MPPT output) Low drop out

Latchup protection for Single Event Upset (SEE) radiation events 50mA current trip setting (2mA MAX expected) In use by AMSAT

Page 60: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

JTAG Programming

JTAG MSP430 Programming Allows for programming and the

MSP430 on-board Connector and height restrictions

not part of PCB requirements Located "outside MPPT area" Not restricted to height

limitations since this is an engineering test component

I2C Communications I2C transmitted to AMSAT

connector Engineering test connector also on-

board for easy access

Page 61: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

PCB - Overview

Page 62: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

Test Plan

Page 63: AMSAT-MPPT Detailed Design Review - EDGEedge.rit.edu/.../FinalDocuments/Detailed_Design/P13271_PPT_MSD_DDR.pdfAMSAT-MPPT Detailed Design Review Dan Corriero Ian MacKenzie Brent Salmi

Circuit Bring-up

Bring up board in stages Regulators Op-amp signal conditioning Output conditioning UC2524A MOSFET Driver MSP430