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AC fan speed control


(@chris24680)
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Joined: 4 years ago
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What's the best way to go about controlling an AC fan speed via brucontrol?

The fan I want to control is a wall mounted extraction fan which currently runs through a basic controller with triac and potentiometer for manual speed control.

Ive seen robotdyn do an AC dimmer module but not sure about the wiring/scripting that would be required to get this working in brucontrol, the module uses two ports on the microcontroller, one for zero crossing and one for the pwm control. I don't really understand how the zero cross input would work and be configured within brucontrol.

Is there a simple way of achieving this speed control with this module or another method, without too much complicated scripting or expensive hardware being needed?

 


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(@pbruno3)
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Joined: 5 years ago
Posts: 332
 

Can you post the module? PWM is easy, but not sure of the zero-crossing you are mentioning.


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(@chris24680)
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Joined: 4 years ago
Posts: 27
Topic starter  

This is the module i was looking at

https://robotdyn.com/ac-light-dimmer-module-1-channel-3-3v-5v-logic-ac-50-60hz-220v-110v.html


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(@pbruno3)
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The Zero-Cross is an output signal from the dimmer telling the micro-controller when the sine-wave of the AC input circuit is at zero. I assume this happens 120 times a second. I'm not fully sure it's purpose, but you would not use this pin if integrating in BruControl anyway.

 

Assuming the PSM pin is a PWM input, you can tie it directly to a PWM output on the MEGA and control it via a PWM/Analog Output Device Element.


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(@chris24680)
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Joined: 4 years ago
Posts: 27
Topic starter  

Ah ok, i assumed this zero cross input would be needed so the PWM wave output from brucontrol and the AC supply wave would be aligned so it knows where to interrupt the wave to achieve the dimming

The pinout diagram for the module

https://robotdyn.com/pub/media/0G-00005677==Mod-Dimmer-5A-1L/DOCS/PINOUT==0G-00005677==Mod-Dimmer-5A-1L.pdf

shows the modules PSM pin as a PWM so i guess Pulse Width Modulation and Pulse Skip Modulation are closely related

I guess for the low cost of this module its worth getting one to give it a try with brucontrol to see if it works, i just dont really want to risk damaging the fan (it was rather expensive)


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(@pbruno3)
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BC doesn't have any type of internal triggering (in the firmware) to change the output based on the input. This could be done in the scripting but it would be way too slow to catch a 60Hz wave!

You might reach out to them to confirm, but I don't think it is necessary.


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(@chris24680)
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Joined: 4 years ago
Posts: 27
Topic starter  

Just found a a different module on ebay that looks like it does the input/output frequency alignment onboard and just takes a PWM signal for control

https://www.ebay.co.uk/itm/124296310513

 


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