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

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

Objectives –Interface a Fuel Cell to the AMPS –Ensure Safe Operation

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

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

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

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%

DC/AC Inverter Tier Electronics – Custom Package –Input VDC –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: ~90V LL with 120V DC input No Previous programming –Cost: $500

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

Transformers 3 single phase transformers (  - Y connected) : –Estimated 75VA rating per phase –Steps up voltage to 208V LL (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 120V L-n on the output of each phase when connected in  - Y configuration – this has not yet been fully verified.

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.

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

Zero Detection

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

Pulse Sequence: 1R – 3F – 2R – 1F – 3R – 2F V o2 (t) V o1 (t) Zero Detection

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 Zero Detection – PCB Board

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

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

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

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

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

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

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

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

Waiting for Pulse Waiting for Falling Edge Calculations Zero Crossing Analysis PWM State Start Triangle Wave Rising Edge? Convert to Q15 Format Calculate Phase Counts YesNo PWM Calculations/ PWM Sync Check Break Calculate Timings/Update Carrier Frequency Turn on PWM Output Calculate/Load Sin Positions in CMPR Registers Increment Counters Software

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

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

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

Budget

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