VFDs for AC motor control are common items. 3 phase AC motors are everywhere, easy to find used, last forever, and are very inexpensive for their HP rating.

The VFD drives I have seen all take AC input, 1 phase or 3 phase. Since the AC gets converted into DC inside the drive, it would *seem* that DC input versions would be easy (hah!) to convert from existing units, or should be cheaper to buy (due to fewer parts) than the original AC input versions.

Does/has anyone know/tried this or have any other information?

What would be ideal is if the VFD drive would send power back to the DC bus during regeneration instead of dumping it into load resistors, but I doubt that is the possible circuit for the same.

 

VFDs with DC bus input are common. Most all higher class VFDs offer it or have it by default. And yes, the regen goes back into the DC bus. But you will have to be able to capture it safely, meaning a lot of capacitors.

VFDs that I can think of (There are more I can't remember) that I've seen used in DC-bus application to date: Omron/Yaskawa, Allen Bradley, Siemens, Lenze.

 

In most VFD's with dynamic braking the braking resistor is across the DC bus circuit and just cycles on in pulses to keep the bus voltage down to a safe level.

With a battery bank as the DC bus power source that regenerative power would just go back to the battery until the DC voltage went to high.