HydroFly: Fuel Cell Project

1. Group Members: -Adam Lint -Chris Cockrell -Dan Hubbard Sponsors: -Dr. Herb Hess -Dr. Brian Johnson HydroFly: Fuel Cell Project

2. Final Presentation Outline Introduction Project Objectives Project Specs Final Design Solution and Validation Individual Components Entire System Problems Encountered Final Steps to Completion Budgeting Questions

3. Objectives • Interface a Fuel Cell to the AMPS • Ensure Safe Operation

4. Functional Specifications Overall interface design specifications: • AC signal MUST BE present on the AMPS • 18-36V DC input from the fuel cell • Output 208 +/- 2% V AC (L-L 3-phase) • Output frequency at 60Hz +/- 0.2Hz • Power flow of 75W through the interface • Dimensions: fit on cart with dimensions 32” x 27” x 18” (2 shelves)* *not including fuel cell, transformers or inductor bank

5. Final Presentation Outline Introduction Project Objective Project Specs Final Design Solution and Validation Individual Components Entire System Problems Encountered Final Steps to Completion Budgeting Questions

6. DC/DC Converter ABSOLPULSE BAP265 - Customized Input 18 – 36 VDC Protection: Current limiting, thermal fuse, reverse polarity protection, 500VDC isolation from output/chassis Output 120VDC ±1% Protection: Current limiting, thermal shutdown Power capability: 200W Efficiency: ~80% (within 0º – 50ºC) Cost: ~$318.00

7. DC/DC Converter Verification Input and output specifications exceeded Device operates efficiently at 160W not tested at 200W because of power supply limitations Measured Efficiency: 86-87% Picture

8. DC/AC Inverter Tier Electronics – Custom Package Input 80-200VDC Output: variable 3 phase AC Switching circuitry: 600V IGBT devices Rated current: 3A RMS at 5kHz TI 2401 DSP: fully programmable I/O plug +15V output, receive and transmit outputs, auxiliary inputs and outputs (digital and analog). Other specifications Max output voltage: ~90VLLwith 120V DC input No Previous programming Cost: $500

9. DC/AC Inverter Verification Proper operation verified at 120V DC input with ~6kHz switching frequency programmed Picture

10. Transformers 3 single phase transformers ( - Y connected): Estimated 75VA rating per phase Steps up voltage to 208VLL (RMS) Filters PWM output Provide a ground isolation Experimental Verification (120V output – single phase) Phase A turns ratio: 1:2.6 Phase B turns ratio: 1:3.2 Phase C turns ratio: 1:4.3 The different turns ratios have been accounted for in the inverter control. The magnitude of each phase can be adjusted to get 120VL-n on the output of each phase when connected in  - Y configuration – this has not yet been fully verified.

11. Inductor Bank • Provides ~142mH per phase for use in controlling power flow (experimentally verified). • Reduces system sensitivity to changes in voltage magnitude and/or phase.

12. Zero Detection • Board designed and built by Dan Hubbard • Gives a timing reference to the TI-2401 DSP on the DC/AC Inverter • Provides the ability to create a 3-phase signal synchronized with the 3-phase system on the AMPS and, ultimately, control the power flow to the AMPS

13. Zero Detection

14. Vo2 Zero Detection Phase 1 Zero Detection Circuits Vop(1) Von(1) Vop(2) Von(2) Phase 2 Zero Detection Circuits Vo1 Vop(3) Von(3) Phase 3 Zero Detection Circuits

15. Zero Detection Vo1(t) Pulse Sequence: 1R – 3F – 2R – 1F – 3R – 2F Vo2(t)

16. Zero Detection – PCB Board • 2-layer board – Vcc, GND • Required external power supply: ±18V • On-board linear voltage regulator: 3.3V • Inputs (3): 120VAC (3-phase) • Outputs (2): serial pulse stream, phase 1 (falling) ref signal

17. Zero Detection - Verification • Circuitry operates as expected • Pulse width of approximately 50µs • Slight error (~20µs) accounted for in software

18. Power Flow Given: For 75W power flow and zero reactive power: To stay within ±10% P and Q:

19. Software • Three Main Functions • Records/Monitors Zero Detection Points • Gives our PWM a starting point • Data used to dynamically adjust carrier frequency of PWM • Detects possible faults situations and shuts off PWM • Creates Sine-Triangle PWM • Triangle wave carrier frequency (~ 6 kHz) • Sine wave generated from sine lookup table • Values passed into Compare Registers which control PWM outputs with user-controlled dead-band time (4 us) • Controls Power Flow • Delta incrementally added over 100 cycles to generate a power flow of 75 W

20. Software While (1) System Initialization Start Yes Switch State Yes Case 1 Waiting for Pulse ISR No Yes Case 2 Waiting for Falling Edge Increment OverflowCounters No Yes Case 3 Calculations Reset ISR Flag No Yes Zero Crossing Analysis Case 4 Return No Timer 2 OverflowInterrupt Yes Case 5 PWM State No Default

21. Software Start Waiting for Pulse Phase 1 Falling? Yes System Synced Waiting for Falling Edge No Pulse Detected and System Synced? Calculations Record Times/Reset Counters Yes Zero Crossing Analysis No Set Next State PWM State PWM Calculations/ PWM Sync Check Zero Crossing Pulse Stream Break Phase 1 Falling Reference Signal

22. Software Start Waiting for Pulse Pulse Ended? Yes Record Times Waiting for Falling Edge No Increment/Decrement Counters Calculations Set Next State Zero Crossing Analysis PWM Calculations/ PWM Sync Check PWM State Break Zero Crossing Pulse Stream Phase 1 Falling Reference Signal

23. Software Start Waiting for Pulse Calculate Pulse Width Waiting for Falling Edge Calculate Time Between Pulses Half Period? Calculations Yes Calculate Half Period Zero Crossing Analysis No Set Next State PWM State PWM Calculations/ PWM Sync Check Zero Crossing Pulse Stream Break Phase 1 Falling Reference Signal

24. Software Zero Crossing Pulse Stream (No Fault) Zero Crossing Pulse Stream (Fault) Start Waiting for Pulse Calculate Actual Zero Crossing with Error Adjust Waiting for Falling Edge Increment/Decrement Counters Calculations Detect Fault? Yes System Shutdown Zero Crossing Analysis No PWM State Set Next State PWM Calculations/ PWM Sync Check Break

25. Software Start Calculate Timings/Update Carrier Frequency Waiting for Pulse No Triangle Wave Rising Edge? Yes Waiting for Falling Edge Calculate/Load Sin Positions in CMPR Registers Calculate Phase Counts Calculations Convert to Q15 Format Turn on PWM Output Zero Crossing Analysis Increment Counters PWM State Increment Counters PWM Calculations/ PWM Sync Check Break

26. Final Presentation Outline Introduction Project Objective Project Specs Final Design Solution and Validation Individual Components Entire System Problems Encountered Final Steps to Completion Budgeting Questions

27. Problems Encountered • Three Main Problems • Zero Detection Reference Signal: Triggered Falling Edge instead of Rising • Edited software accordingly • Resulted in simpler sine-triangle PWM software • Transformer: Core Losses drew too much current from Fuel Cell • Found smaller transformers • Recalculated Turns Ratios • TI2401 DSP: Flash Memory Damaged • Flex-Trace Connection used to program DSP still a risk • Ordered new DSP and is scheduled for delivery on Monday • Expected repair date: 12/13/05

28. Final Steps to Completion • Replace DSP – 12/13/05 • Finish interfacing 12/13 – 12/15 • Upload and test the code for voltage magnitude and phase required for synchronization and power flow • Final Demonstration 12/15 • Final Report 12/15 • User’s Manual – included in final report

29. Budget

30. Zero-Detection Circuitry QUESTIONS? OUTPUT 208V ± 2% AC 3-phase Synchronous Freq. 75W AC 3-phase Synchronous Freq. AMPS 120V DC ±1% Output: 208VLL Fuel Cell Trans-formers and inductor bank DC DC DC AC : Y INPUT 18-36V DC Control Special thanks to Greg Klemesrud, JJ, Steve Miller, Don Parks