Low Cost Automatic Speed Control of Single Phase AC Fan Motors

1. Low Cost Automatic Speed Control of Single Phase AC Fan Motors SmartFan MMC series Winner of ASHRAE’s 2003 Technical Innovation Award Motor Control with Intelligence

2. What motors are we talking about? • Single-phase AC motors under 1 HP • Consists of small motors found in “muffin-style” fans all the way to your typical axial AC induction motors for duct air movement. Motor Control with Intelligence

3. Controlling the speed of small AC motors • What are your options? • RHEOSTAT • VARIAC • MULTIPLE MOTOR WINDINGS • TRIAC • VFD / INVERTER Motor Control with Intelligence

4. Why choose a TRIAC controller? • Most popular choice in your typical wall-mount knob control • Significant cost savings and smaller size than other options Motor Control with Intelligence

5. How does a TRIAC work? • Does not change frequency, but chops the wave, reducing the magnetic power in the motor and slowing it down. Motor Control with Intelligence

6. Which motors are best for TRIAC control? • Key is in the amount of “slip” the motor will allow. • Type F motors are preferred as they allow more “slip” (they are typically referred to as fan motors - built for varying loads) . • Most common fan motors are either PSC (Permanent Split Capacitor) or Shaded Pole. • Best motors are typically “multi-tap” motors as they are designed to run at different speeds. Motor Control with Intelligence

7. So why aren’t TRIAC controls used more often in HVAC&R applications? • Standard TRIAC controls have been limited in their ability to properly chop the line voltage wave for motors - work great on resistive loads such as lights, but not on motors due to the Amplitude and Phase of motor currents. • This requires a large minimum delay of TRIAC firing which limits their output range. • OK if custom matched to a specific motor for each different application. Motor Control with Intelligence

8. New MMC TRIAC controller is different • TECHNOLOGY • Microprocessor-based logic • APPLICATIONS • Control a wider range of fans/blowers/motors • FLEXIBILITY • Dip-switch selectable control parameters Motor Control with Intelligence

9. MMC TECHNOLOGY • Precise timing and control of TRIAC firing angle minimizes “voltage asymmetry” and the resultant generation of DC currents in the motor and input power lines. • MMC solves this problem with “microsecond precision”. • With real-time monitoring and control of output voltage. Motor Control with Intelligence

10. MMC TECHNOLOGY • Example of “asymmetrical” waveform that results from unequal positive and negative TRIAC firing times. Motor Control with Intelligence

11. MMC TECHNOLOGY • Example of wave “symmetry” due to precise timing and control of TRIAC firing angle. Motor Control with Intelligence

12. MMC TECHNOLOGY • Real-Time calculation and control of the RMS Output Voltage (on a cycle by cycle basis) enhances motor speed control and stability. • Other TRIAC controllers are “constant phase angle” with “fixed” firing delay. • Our VRMS output doesn’t care about phase angle - the output voltage remains fixed independent of load on the motor. Motor Control with Intelligence

13. MMC TECHNOLOGY • Example of “typical” TRIAC where commanded output is equal to 68V with no air flow restrictions. Motor Control with Intelligence

14. MMC TECHNOLOGY • Example of the same TRIAC where the same commanded output is now equal to 104V when the airflow is blocked. Motor Control with Intelligence

15. MMC TECHNOLOGY • Example of “MMC TRIAC” where commanded output is equal to 68V with no air flow restrictions. Motor Control with Intelligence

16. MMC TECHNOLOGY • Example of “Nimbus TRIAC” where the same commanded output is equal to 67V when the air flow is blocked. Motor Control with Intelligence

17. MMC TECHNOLOGY • Bottom Line: MMC CONTROLS BETTER • Elimination of “voltage waveform asymmetry” by constantly checking and adjusting the time delay between the input voltage zero crossing point and the application of the TRIAC gate pulse • Amplitude and phase of the motor current is a function of motor construction, mechanical loading, and input voltage frequency • Simple TRIAC controllers are usually optimized for one set of conditions and cannot change. Motor Control with Intelligence

18. MMC TECHNOLOGY • Bottom Line: MMC CONTROLS BETTER • True VRMS output to enhance motor speed control and stability. • Control motors of different power ratings under changing conditions with no adjustment or loss of performance. Motor Control with Intelligence

19. MMC Energy Savings: • Up to 25% power savings when running AC motors at idle speeds of around 50%. Motor Control with Intelligence

20. MMC APPLICATIONS • Control a wider range of fans, blowers, and motors. • Ceiling fans • Exhaust systems • Pumps Motor Control with Intelligence

21. MMC Flexibility • Two different models currently available: • MMC-100: 120-240 Volt , 7A, with single temperature sensor • MMC-250: 120Volt or 240 Volt, ½ - 1HP (7A), Hot & Cold temperature sensors, “brown-out” shut down protection Motor Control with Intelligence

22. MMC FLEXIBILITY • Dip-switch selectable control parameters • Pick your own fan control range. Motor Control with Intelligence

23. MMC FLEXIBILITY • Choose your control temperatures (full speed operation) • 4 Hot and 2 Cold temperature settings to chose from Motor Control with Intelligence

24. MMC FLEXIBILITY • Choose your motor idling speed Motor Control with Intelligence

25. MMC FLEXIBILITY • Additional features: • Fan motor full speed start time selection • Power “brown-out” shut down protection • (unit will shut down below 80 or 160V and start back up at either 90 or 180V) Motor Control with Intelligence

26. MMC FLEXIBILITY • Easy customization for unique or special applications • Need different control parameters: • different set-points, unique sensors • IT CAN BE DONE !!! • Micro-processor based software lends itself to easy changes to meet your needs Motor Control with Intelligence