Controlling AC air Pump with PWM

I don't know the real answer, but I'm guessing it will depend on how the pump is actually built. If it is a linear design where a rod inside a coil simply moves back and forth to move the diaphragm you will have to match your PWM timing to the normal cycles in your AC power otherwise it may try to move the diaphragm one way when it needs to go the other way. Instead of changing the speed you would change how much the diaphragm moves. If it a normal rotational type motor and linkage it probably wouldn't be a problem.


Started to think the answer is probably no. AC motors are usually controlled by altering the frequency of the AC signal. With a PWM you may end up with a situation where your internals are not lined up right for the particular portion of the AC cycle. Either the motor may jump to get everything in line, or will be moving against the magnetic field and create a lot of heat.
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Joined Sep 17, 2013
Try googling "ac dimmer pwm". Something thrown up there, although intended for lamp dimming, may work with your AC pump motor, but there's no guarantee it will.
A suppressor across the motor terminals should be beneficial.