# Presentation: 143768

## Section 11

_***Section 11***_
***Power***

*** ******. . . Allan Billings***
*Swales Aerospace*

## Power System PSR Outline

***Power System PSR Outline***

***EO-1 Power System Description***
***Power System Distribution Block Diagram***
***Power System Characteristics/Requirements***
***PSE Box Level Proto-Flight Test Flow***
***PSE Subsystem Level Testing***
***EO-1 Verification Matrix***
***Description of Tests in Verification Matrix***
***Test Results***
***Significant Non-Conformance and Corrective Actions***
***Configuration Changes***
***Action Item Status***
***Power System Statement of Readiness***

## EO-1 Power System Description

***EO-1 Power System Description***

***Unregulated Power Bus (+28Vdc ± 7Vdc)***
***Single, Super Nickel Cadmium, 50AHr Battery (Flight Heritage)***
***One Deployable Solar Array, 750W BOL at 37V Peak Power Pt,  At 60************C, Sun Intensity =.97***
***Digital, Shunt Regulated, Direct Energy Transfer Power System (Flight Heritage)***
***7 Digitally Switched Solar Array (segment) Shunts (gross power), One Unswitched Solar Array Segment, and One PWM Solar Array Segment (Boost Converter) for Fine Control***
***PSE contains the following 6 Printed Wiring Boards***
***PSE RSN ---Command & Telemetry for PSE & Interface to S/C on 1773 BUS***
***LVPC provides (Current Limited) Switched (1A) & Unswitched 28V Power to S/C as well as 5V ±15V Power to PSE***
***Output Module 1 & 2 provides (Current Limited 15A) Switched & Unswitched power to S/C***
***Solar Array Module Provides for Shunting the Solar Array & charging the Battery ***
***Battery Module Provides for S/C & GSE Interface as well as Battery Telemetry***

## PSE Power Distribution

***PSE Power Distribution***

## Power System Requirements / Compliance

**ALL PSE SPECIFICATION REQUIREMENTS ARE MET  **

## Requirements / Compliance

**ALL PSE SPECIFICATION REQUIREMENTS ARE MET  **

## PSE Box Level Qualification Test Flow

**Vibration Test**

**Thermal Test**

- Performance

- Test

- •

-  3 Axis

- •

-  0.16g2/Hz

- •

-  Functional Test between axis

- •

-  Aliveness during vibration

- •

-  4 Cycles

- •

-  +60oC hot turn on

- •

-  +55oC soak, Thermal Performance test

- •

-  -20oC cold turn on

- •

-  -15oC soak, Thermal Performance test

- Performance

- Test

- Performance

- Test

***PSE Box Level Qualification Test Flow***

_**Rework for Op-amp Repair and 1773 Replacement**_

**•**

** ****Vibration - 3 axis, .04g2/Hz**

**•**

** ****Thermal - 4 cycles, -15oC to +55oC, turn on @-20o & +60o**

_**Rework for 1773 Repair**_

**•**

** ****Vibration - 1 axis, .04g2/Hz**

**•**

** ****Thermal - 4 cycles, -15oC to +55oC, turn on @-20o & +60o**

_**Anomaly During Hot Cycle**_
**Could not command SSPC Corrected  by adding wait state in software**

_**Test Anomaly after Vibration in X Axis.**_*** ***
**Piece of lead lodged between SSPC pin 9 and heatsink. Removed wire from through hole. Filled all through holes with uralane and retested successfully. Not vibration related.**

## PSE Subsystem Level Testing

***PSE Subsystem Level Testing***

***Performed Load Step Testing ***
***Verified stability and transient response***
***CPT tests of entire S/C characterized over several orbits at different VT levels***
***Further Testing of the PSE ***
_***Tested FDC functions***_***: Battery Temperature FDC, Battery Voltage FDC, Battery Differential Voltage FDC, Output Module FDC***
_***Test Battery PRT***_***:  Battery temperature sensors, both primary (PRT) and backup RT were tested including failure modes***
_***Partial Power tests***_***:  Tested system with simulated solar array string losses as well as the solar array at EOL & in Eclipse***
***Hardware/Software Model of PSE***
***Used to validate tests or changes in PSE code before actual code is tested in the PSE ***
***Model validated through correlation of multiple test results***
***Loop Phase/Gain Measurements performed on MAP ETU***
***Worst Case (10% duty cycle) Outer loop (A out & Battery current), ******Phase Margin/Gain Margin = 70 deg/-12dB***
***Inner loop (SAM current), Phase Margin/Gain Margins = 60 deg/-20dB***

## Verification Matrix

## Description of Tests in Verification MatrixPSE

**PSE Verified Through Qualification by Similarity,  Verification by Analysis and Successful  Verification by Test**

***Description of Tests in Verification Matrix******PSE***

***Qualification by Similarity***
***Static Load Test and EMC/EMI Test performed on MAP PSE-- Covered as Special Topic***
***Verification by Analysis***
***Venting/Pressure Profile –Venting put into PSE chassis. Analysis reviewed and accepted***
***Radiation – Ray Trace Analysis by Litton showed compliance to 15KRAD total dose***
***Verification by Test***
***Random Vibration - Passed***
***Thermal Cycles - Passed***
***Interface Verification - Passed***
***Functional - Passed***
***Weight--- Actual tested weight = 14.8 Kg    Requirement  = 16 Kg***

## Description of Tests in Verification MatrixBattery

***Description of Tests in Verification Matrix******Battery***

***Qualification by Similarity (XTE and TRMM)***
***Venting/Pressure Profile - Passed***
***Verification by Analysis***
***Life Test - Passed***
***Static Load - Passed***
***Verification by Test***
***Random Vibration - Passed***
***Thermal Vacuum - Passed***
***Interface Verification - Passed***
***Functional - Passed***
***Weight--- Actual tested weight = 59Kg - Passed ***

## Test Results:  Calibration/Characterization

***A trending procedure was run in the background throughout TB/TV capturing the critical Power System telemetry points every 15 sec***
***The bus voltage, battery voltage, battery current, battery temperature, solar array module current, chassis current, output module #1 current, and output module #2 current were sampled every 15 sec and compared to the GSE/Umbilical telemetry***
***All PSE telemetry was in agreement with GSE/Umbilical telemetry to within acceptable limits and the error was not changing with TV temperature***
***The PSE was fully characterized in all modes of operation:  full charge/current, limited charge, V/T clamped charge, and trickle charge***

## Significant Test Results Over Thermal Vacuum/Thermal Balance Test

***Significant Test Results Over Thermal Vacuum/******Thermal Balance Test***

- ALL RESULTS as EXPECTED and NOMINAL

## Significant Test Results Over Thermal Vacuum/Thermal Balance Test

***Significant Test Results Over Thermal Vacuum/******Thermal Balance Test***

***Extensive VT testing defines proper curve for this mission***
***Determined that VT4 resulted in 100% SOC only at very end of charge cycle(day).  VT5 resulted in 100% SOC well before end of day and will be nominal setting for mission.***
***Total Trouble-Free Hours & Total Hours***
***PSE and Battery were LEO cycling through-out entire TB/TV test (~20 days) with no trouble***

## Significant Non-Conformanceand Corrective Actions

***Significant Non-Conformance******and Corrective Actions***

***System Stability (History)***
***Original software did not have VT Controller...one since designed***
***Oscillations occurred***
*EGSE Problem: Umbilical rack slow response in turning on SAS.  Since has been rectified using Current Limit Box in-line with umbilical*
*HW Problem: Stability Analysis was run and results were to reduce the dc gain  to increase stability margins.  (Hardware changeout....resistors)*
*SW Errors: Fixed during clean-up of the PSE code (Final code tested on November 18, 1999)*
***Clean-up of aforementioned HW/SW problems resulted in stable PSE***
*VT Control verified working properly*
*Incorporated MAP changes/suggestions*
***Allow VT loop to reduce battery current below trickle charge level***
***Use Unfiltered battery current signal versus filtered signal***
***Filtering LSB toggling in the control loop***
***LVPC Output 9 (nadir deck) damaged, removed from service - Covered as Special Topic***
***Short circuit protection of the PSE - Covered as Special Topic***

## Configuration Changes

***Configuration Changes***

***Battery module***
***Changed differential voltage gain due to change in battery type from Nickel Hydrogen Battery (MAP) to a Super Nickel Cadmium Battery (EO-1)***
***Battery-cell pressure is not used because EO-1 uses a Nickel Cadmium Battery***
***Software and telemetry modified because of the change of battery type (SOC calculation, cancel hydrogen pressure in telemetry)***

## Action Item Status

***Action Item Status***

***RFA’s -- Closed***
***PRs and PARs -- Closed***
***EMI/EMC test performed on MAP & EO-1 S/C - Covered as Special Topic***
***Close-Out of Open Items -- No Open Items***
***No Redbook Candidates***
***Statement of Readiness & Residual Risks***
***The Power System is Ready for Launch***
***All required test procedures are complete and released***
***The Solar Array is awaiting final inspection***
***The Battery handling plan is complete and released***
***The PSE has been thoroughly tested and is ready for launch***