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Micro-Hydro System Utilizing Rain Runoff

Micro-Hydro System Utilizing Rain Runoff. Group # 9 Mark Boktor Jeff Shearer Charmin Patel TA: Tamer Rousan. ECE 445 May 4, 2010. Introduction. Purpose To utilize runoff rain water to generate power for a sump pump in case of a power outage. Features Regulates DC output voltage

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Micro-Hydro System Utilizing Rain Runoff

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  1. Micro-Hydro System Utilizing Rain Runoff Group # 9 Mark Boktor Jeff Shearer Charmin Patel TA: Tamer Rousan ECE 445 May 4, 2010

  2. Introduction • Purpose • To utilize runoff rain water to generate power for a sump pump in case of a power outage. • Features • Regulates DC output voltage • Converts DC to AC for electric machine functionality • Outputs up to 250W

  3. Block Diagram • DC Generator: Outputs DC voltage proportional to speed • DC-DC Boost Converter: Boost DC voltage to 170V and • regulates output • Analog Voltage Regulating Circuit: Provides regulated • power for IC chips • DC-AC Converter: Inverter which converts 170VDC to • 120Vrms at 60Hz • Low-pass RC Filter: Makes inverter output more • sinusoidal

  4. Generators • Initially planned on using AC generator • Used two DC generators on a single shaft • Generators connected in series Shaft link

  5. Generator Output

  6. Generator Efficiency vs. Speed - For 9.1Ω load - Importance of gearbox

  7. DC-DC Converter Requirements: • Receive varying voltage from generator • Must be able to adjust duty ratio => use a PIC • Output approximately 120*√2 Vdc for DC-AC inverter The most important equation:

  8. Part Sizing Capacitor sizing Inductor sizing MOSFETs and Diodes - Obey the ratings

  9. Feedback • Reference voltage and scaled output voltage • Reference voltage is 2.5 V • Scaled output is 2.5 V when output of the first stage is 70 V • Compare the two voltages to determine next action

  10. Why 2-stage? • Scaling a lower voltage allows for greater accuracy

  11. Finite Duty Ratio Adjustment • Accuracy limited by microcontroller • Period of control signal determined by: Tosc*4*(TMR2 Prescale)*(PR2+1) • Duty ratio determined by: “value”/PR2

  12. Finite Duty Ratio Adjustment • Want period to be as small as possible • Tosc and TMR2 Prescale basically fixed • PR2 and “value” must be nonnegative integers • For 50 kHz: PR2 = 99

  13. The “Close Enough” Approach • The output will not be stable when the duty ratio is constantly varying • Designate a range of outputs that are acceptable, and do not adjust duty ratio when in that range • Sump pump runs OK if voltage is not perfect • Noise

  14. Results – Efficiency

  15. Results –Output variation with steady input

  16. Results – Output Voltage Variation Peak variation is about 3 V, 1.76%

  17. Results – Sudden Input Variation

  18. Input Variation – Does it matter? • Is 10 V change in 200 ms realistic? • Momentum of turbine • Duty ratio can change in about 10 ms

  19. DC-DC Converter – Final Design

  20. DC-AC Converter • H-Bridge configuration • Input: 170 VDC • Output: 120 VRMS at 60 Hz

  21. Choosing the MOSFETS • N-channel MOSFET • @VGS = 10 V • RDS(on) = 0.39Ω • Drain-Source Voltage: 500V • Drain Current: 14 A

  22. Gate Driver Circuit

  23. Gate Driver Waveform

  24. Pulse Width Modulation (PWM) • Sinusoidal Output (SPWM) • Sine wave at 60 Hz • Sawtooth wave at 50 kHz • Comparator outputs SPWM • UC3825 and TL598

  25. PWM Waveform

  26. Output with PWM

  27. Complications with PWM Output • Resonant filter (LC) • Maximum Duty ratio: 50% • Minimum frequency: 1 kHz

  28. Using PIC • Use PIC to generate two 60Hz opposite square waves • Output will replace PWM and be fed to the gate driver

  29. Advantages of Using PIC • Simplifies circuits • No sine generating chip necessary • No need for -5VDC for sine chip • No high frequency noise from PWM

  30. Results Using PIC PIC output 60Hz square wave Outputvoltage of Inverter Good frequency output

  31. Efficiency of Inverter

  32. Low-pass RC Filter Cutoff frequency: Transfer Function:

  33. LPF

  34. Efficiency of Inverter with LPF

  35. Inverter with LPF

  36. Efficiency with Induction Machine

  37. Battery/Voltage Regulating • 12V Heavy Duty Battery • In series with generator • Provides power to Driver/PIC • Provides necessary high starting current for sump pump

  38. Future Work • Test with water turbine • Integrate DC-DC converter with DC-AC converter • Improve efficiency of DC-AC converter and LPF • Add method to charge battery when sump pump is not operating

  39. Ethical Considerations • To avoid injuring others, their property, reputation, or employment by false or malicious action • To be honest and realistic in stating claims or estimates based on available data

  40. Thank You • Ali Bazzi • Kevin Colravy • Mark Smart • Grainger Power Lab • All ECE 445 TA’s

  41. Questions ??

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