Many (if not most) VFDs allow you to input DC directly into them, as long as it meets the DC bus voltage requirements. Just ask your favorite VFD manufacturer. The reason why some do not is only because of where they tap off power to run the electronics. Most take their power from the DC bus, so they will be happy with a DC input. A few however have a separate AC power supply for the control power, so if you supply DC, it bypasses that power supply.
You can also do a search for AC vehicle drives or small "traction drives", which also take DC and put out AC, then you don't end up wasting $$ on the rectifier section of a VFD.
One thing to be careful of however, you should not use the dynamic braking feature of a VFD when being supplied by batteries. The regenerated voltage may come back onto the batteries too fast and damage them. |