I had a request from a customer to put VFD's on their condenser fan motors. This is a 208/1/60 HVAC unit.

I have never encountered this before. Would I have to put a phase converter on then a VFD. How does phase conversion affect the amps per leg? Would that cause problems with the VFD?

I would prefer to put a variable speed control on the first fan on each circuit and stage the rest as on/off but I am not sure if I convince everyone between me and the end user that that is the way to go.

Any thoughts or expertise would be appreciated.