Vfd For Single Phase?

[RJSakowski]

Has anyone out there in HM land used a VFD for controlling a single phase motor? Any thoughts as to why this wouldn't work? (I realize that the instant reverse goes away.)

Thanks!

 

[den-den]

It would work for a split phase motor but they are usually only small fraction of a HP. It will not work for any single phase motor that has a centrifugal starting switch (most single phase motors) to slow the motor below normal speed although it would be possible to run the motor somewhat faster than normal speed. If the motor were to slow down, the centrifugal switch would energize the start winding and burn it out.

 

[RJSakowski]

It would work for a split phase motor but they are usually only small fraction of a HP. It will not work for any single phase motor that has a centrifugal starting switch (most single phase motors) to slow the motor below normal speed although it would be possible to run the motor somewhat faster than normal speed. If the motor were to slow down, the centrifugal switch would energize the start winding and burn it out.

Thanks den-den

In my experience, the centrifugal switch cuts out at considerably lower speed than normal operating speed. Additionally, an external switch could be added to prevent activation of the start winding.

I would be looking for operation between 30 or 40% of nominal, primarily to drop spindle RPM from the current minimum of 150 rpm for certain threading operations.

 

[mksj]

There is only one VFD that I am aware of that is specifically designed to work with certain types of single phase motors either PSC (permanent split capacitor) or shaded-pole single phase induction motors.
http://www.invertekdrives.com/variable-speed-drives/optidrive-e2-single-phase/

Since one can get low cost VFD and 3 phase motor combinations, this would seem a reasonable alternative and still less expensive than the E2. Do not know enough about any other options for single phase motors and how they would perform at reduced speed. Is there any option for a dual pulley with different ratios?