Transcript Closed-Loop Rotational Speed Control of Cooling Fan David Choi Jay Gainer Shad Laws Karl Stensvad Objectives • Closed-loop control of cooling fan based on desired speed • Fine tune LabVIEW parameters.

Closed-Loop
Rotational Speed
Control of Cooling
Fan
David Choi
Jay Gainer
Shad Laws
Karl Stensvad
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
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
Logic Overview
Mechanical Features
• Cooling fan housing
• Encoder
• Airflow resistor plates
• Circuit board
Electronics
•Tachometer
•Proto-board
•Circuit Board
User Interface
Software
Setting Trial Speed
Determination of Speed
Changing Output Voltage
Determination of Error
Calculating Power
Demo
Results and Analysis
• Fan Rotational Speed
• Power Draw
• Efficiency
• Error
Power Draw
4
4500
3.5
4000
3000
Watts
2.5
2500
2
2000
1.5
1500
1
1000
0.5
Power 500
0
0
17.5
35
52.5
70
87.5
105
Time (sec)
122.5
140
Actual RPM
0
157.5
Actual RPM
3500
3
Efficiency
18000
Actual RPM
16000
Average Efficiency
14000
12000
10000
8000
6000
4000
2000
Iteration
4801
4501
4201
3901
3601
3301
3001
2701
2401
2101
1801
1501
1201
901
601
301
0
1
RPM or Relative Efficiency
20000
Error
Desired RPM
Observed Error
4500
140
4000
120
100
RPM
3000
2500
80
2000
60
1500
40
1000
20
500
0
0
1
501
1001 1501 2001 2501 3001 3501 4001 4501
Iteration
Percent Error
3500
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