Harvest power from AC drive?

Hi forum members

Is this possible?

The idea would be to harvest the back emf from an AC motor drive and feed to grid or store it.(just like regenerative braking)
How does it sound?
Valuable feedback needed as always

Thanks and regards

Do you mean when you turn the motor off instead of coasting to a stop you would put the back emf into a battery or something? My golf cart has a PM brushless DC motor and does it.
If you mean while it is running ---- there is no free power.

Its not uncommon to do that with larger motors in high powered applications.

First we need to know how big of motor, what is its application, and what method of line connection it is using now.

tcmtech said:

Its not uncommon to do that with larger motors in high powered applications.

Click to expand...

Under what conditions? Certainly not with a steady-state load.

Under what conditions? Certainly not with a steady-state load.

Click to expand...

In large industrial applications regenerative braking is fairly common. Mostly in applications where a large mass needs to regularly change direction or do a considerable amount of start and stop actions.

I became familiar with the concepts when I worked in the coal mines as a student many years ago. The massive drag lines and electric shovels are all electrically powered and use regenerative braking on all their normal movements. Its a huge power saver that way. I have also seen it used on large manufacturing machines where they have a massive moving components the can produce a considerable return power when slowing down or doing some level of speed change.

For small scale its not really practical though. If you cant return more than 10% of your used power and have that pay for the added regenerative braking related equipment in offset costs in a reasonable time line its not worth it.

Thats where the OP needs to specify what he is doing along with the related power that is being wasted by not using regenerative braking.

Hello all

Thanks for the valuable feedback.Much appreciated.

THIS is the idea which i am looking for.
This ones ANOTHER

"ronv" : Do you mean when you turn the motor off instead of coasting to a stop you would put the back emf into a battery or something?

Yes i mean that.

tcmtech, i agree with you. This is for a large industry and power lost in braking is close to 5 Mw

Can someone explain how the inverters run w/o batteries to maintain a constant o/p voltage since the i/p dc bus will not be constant and depend upon the braking duty cycle?

Please get back

Those are basically grid tie inverters which are not input power dependent so they can work with the variable power coming off the main VFD units dynamic braking output without problems.