Controlling single phase motor with VFD.

[Compositepro]

I was reviewing the manual for a Chinese VFD and was surprised to see that it could be used to control a single phase motor from a single or 3-phase source. It shows U, V, W output with W connected to the capacitor lead after the capacitor is removed. What do you guys think of that?

Page 6 of the manual:

http://myosuploads3.banggood.com/products/20190919/20190919015909SKU792664.pdf

 

[jraef]

Those Chinese no-name drives are poorly marketed and the suppliers don't really care. They are NOT good for single phase motors, despite what the website says. But if you buy one and try to return it, they disappear or at least go silent. Steer clear...

There ARE legitimate VFDs for CERTAIN TYPES of single phase motors, namely PSC (Permanent Split Capacitor) and Shaded Pole. Both of those can be controlled other ways though, and the single phase VFDs are very expensive comparatively. It's often simpler to replace the motor with a 3 phase and use a VFD that can accept single phase input and 3 phase output.


" We are all here on earth to help others; what on earth the others are here for I don't know." -- W. H. Auden

 

[Compositepro]

If it had a centrifugal switch would not the VFD provide a phase shifted voltage to the start winding below switching speed and switch out the start winding at higher speeds? I am not considering doing this but it seems possible.

 

[itsmoked]

Changing what's connected to the output of a VFD that's outputting is the very fastest way to kill one. The enormous inductive kick hitting a rapidly switching power semiconductor does very bad things. No motor with a switch in it is appropriate.

BTW that had to be the worst Chinese manual I've seen yet!

Keith Cress
kcress -

http://www.flaminsystems.com