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I would like to add closed loop spindle control for my linuxcnc, and was wondering if I would be able to use something like this www.inmojo.com/store/inmojo-market/item/...al-ac-dimmer-module/ with my 1hp motor. It requires 1 input to determine the zero crossing, and a pulse trigger output using a triac. Has anyone done this before?
Thanks,
CP

CptanPanic wrote:You could use it to adjust the torque, but not the speed. I suspect that is not what you want to achieve.
Induction motor speed depends on frequency, not voltage.

The router used is either a bosh colt, or the small ridgid, which are 1hp motors. I do not know exactly what type of motors they are, but saw online that there is a triac in the routers internal speed controller. Here is what the motor looks like mdm.boschwebservices.com/files/r19331v21.pdf

CptanPanic wrote:
Ah, I suppose I should have asked what kind of spindle motor it was.

Power tools typically use a brushed "Universal" motor These are effectively a DC motor which also works on AC (as the field coils and rotor coils both reverse at the same time on the negative-going half of the mains waveform). In that case a simple Triac "dimmer" ought to work. (though one intended for lighting might struggle with the inductive load that a motor is)

are you trying to achieve something like "SuperPID" or controlling the output speed with linuxcnc?

a closed loop speed controller is not just about reading the current RPM and increase the motor power until you reach the desired RPM... you need to take into account the amount of time it takes for the RPM to increase when the power is increased and lots of other factors, hence the use of PID (which can be achieved inside your PC with Linuxcnc).

turning on the triac with a zero crossing optocoupler is not a viable way for controlling the speed of a universal motor, what you need is to detect the zero cross, and then fire the triac after a specific time to be able to variate the amount of power (not speed) through the motor