1. Closed-Loop Rotational Speed Control of Cooling Fan David ChoiJay Gainer Shad LawsKarl Stensvad

2. Objectives Closed-loop control of cooling fan based on desired speed Fine tune LabVIEW parameters to quickly and accurately adjust between speeds To plot power usage and efficiency at different fan speeds To plot power usage and efficiency with different intake restricting

3. Overview Use small light bulb and photoresistor to create encoder Encoder relays fan speed to DAQ LabVIEW interprets encoder input and varies voltage across fan to maintain desired RPM Read current to the fan to calculate power usage and fan efficiency

4. Logic Overview

5. Mechanical Features Cooling fan housing Encoder Airflow resistor plates Circuit board

6. Electronics Tachometer Proto-board Circuit Board

13. User Interface

14. Software

15. Setting Trial Speed

16. Determination of Speed

17. Changing Output Voltage

18. Determination of Error

19. Calculating Power

20. Demo

21. Results and Analysis Fan Rotational Speed Power Draw Efficiency Error

29. Conclusion We successfully wrote a program that controls the fan speed We verified that power draw increases as airflow restriction and RPM increase We found that efficiency decreases as airflow restriction increases