VFD connected to Solar inverter output

[Mayyad]

Hi,

Is it safe to connect a VFD to Off-Grid Solar inverter output? -Don't want to use soft start-

 

[BentleyJ]

The VFD will take the AC and rectify to DC which is filtered and converted back to a variable voltage/frequency AC in the same manner as the off-grid inverter. There really shouldn't be any interference of the high frequency control signals between the 2 devices. I can't think of any reason the inverter can't operate a VFD.

Anyone else on the forum feel free to comment if I'm missing something.

 

[Batavian]

I have a commercial 3 phase vacuum sealer. I use a VFD and feed 240 split phase and output 3 phase. Have used it with 6500ex and 6000xp have had no issues. Used it a couple days ago.

 

[RCinFLA]

Most of the cheap VFD's have simple rectifier-filter for converting AC input to high voltage DC for the VFD PWM drive.

This creates high peak currents on AC input draw. (high current crest factor). Current peaks at AC input sinewave voltage peaks can be 4x to 8x rms AC current drawn.

It is poor power factor but the high current crest factor is more of an issue. High peak current crest factor load is often what causes the 'flickering lights' AC output voltage instability of inverters.

 

[Dave911]

Put a line choke between your inverter and the vfd. The inductors at the bottom are line chokes. This is sitting in front of me. These prevent rf from backing into the plant power system and causing harmonic issues in the plant power system. Most unfiltered vfds create an incredible amount of noise on the power lines if left unfiltered. They are very common and relatively cheap. Automation Direct has them as well as most motor and drive distributors.