I'm looking for a simple speed controller for a brushless AC motor.

[trilect]

Hi folks, I'm putting together a simple shop air cleaner and need a speed controller for the beast. The motor I need to control is a 1/5 hp induction motor attached to a cage fan.

I found loads of brush motor control schematics on the web but none of the VFD type.

Any advice?

[Al_The_Man]

I don't think you will find many for 1ph induction motor as they do not control well, they drop out of speed control and stall when dropped too low or loaded.
For 3ph there is quite a few designs.
Al

[trilect]

This induction motor appears to have 4 field coils, I wonder if I could possibly cut the wires going to them and setting up a switch system to cut them in and out of the circuit.

Do you think that would work?

[Al_The_Man]

I would'nt even attempt it, you will probabally screw the motor right up. If you really want some control, a used three phase motor that size should not be much, although the lowest voltage is probabally going to be 220v, the input to the VFD would be 1ph.
If 220 is a problem you could look at a small universal motor as is used in shop vac's etc. There are many controllers for this type.
Al.

[DieGuy]

You know the new furnace motors have 2 speed blowers in them.