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Fan stutters/stalls below 50%
iamme9182
I am testing out controlling a vacuum( https://www.lowes.com/pd/Shop-Vac-1-5-HP-Portable-Wet-Dry-Shop-Vacuum/3160385 not much info on the motor here ) with an esp32 and robotdyn ac dimmer. When the level is less than 40% or so the fan does not run at all and at around 50% it seems to stutter and pulse (but does run). Even at 50% the fan is a bit too aggressive so i would need it to be lower to be useful. Do I just have the wrong parts or does this sound like something else I am doing wrong?
renatoa
Are you using wifi during the control ?
My experience with ESP8266 is disappointing, interrupts and wifi doesn't work well together. Not tested with ESP32 though...
What code are you using to control the fan ? zero-cross edge used ? How is the firing angle computed from the input value ?
iamme9182
https://github.co...ht-Arduino
is the library I am using and I am not using WiFi. I don't know how it is computed there but can try to decipher it.
Is there a specific method I should be looking for it to do?
Edited by renatoa on 02/07/2021 2:45 AM
iamme9182
Well found part of my issue, I had apparently reverted the library at some point and lost my change to use 60hz instead of the default 50hz. With that fixed I can get down to ~30% fan power without stalling but it still has some pulses where the power seems to jump 5-10%(but not recognized on the esp32) for a second every 30 seconds or so. Does this seem like expected behavior when dimming an AC fan?
renatoa
Nope, there are testimonials even under 10%, check here, and following posts:

https://homeroast...post_72589
iamme9182
I think I found my issue, putting a multimeter on the output of the dimmer the voltage is stable with no load. When I turn the fan on the voltage gets very unstable and jumps 15v then bounces around a 20ish volt range around there. Apparently this dimmer is meant for resistance load not inductive so I added a snubber circuit with a resistor and capacitor I had lying around. With my initial testing the output looks much more stable at low power.

I learned that the opposite of a snubberless triac is not a built-in snubber but one I need to add. Oops
renatoa
Glad you found the reason and shared with us, for future knowledge.
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