Why synchronous motor with VFD
Why synchronous motor with VFD
(OP)
Synchronous motors are preferred at ratings of say, 10MW and above for better efficiency. But, when motor is driven through variable frequency drive, is there stil a reason to go in for synchronous design?
I have come across a 25MW motor with VFD, but synchronous design recently.
Appreciate your inputs. Thanks in anticipation.
I have come across a 25MW motor with VFD, but synchronous design recently.
Appreciate your inputs. Thanks in anticipation.





RE: Why synchronous motor with VFD
RE: Why synchronous motor with VFD
RE: Why synchronous motor with VFD
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: Why synchronous motor with VFD
RE: Why synchronous motor with VFD
It's intresting project, please see attached link:
ht
Regards.
Slava
RE: Why synchronous motor with VFD
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If we learn from our mistakes I'm getting a great education!
RE: Why synchronous motor with VFD
Thanks for the link. It is interesting.
The document is about a 48MW compressor with VSD and Synchronous motor.
The max speed is 3750rpm. Probably, the high speed explains the reason for selecting synchro motor (Thanks to ScottyUK).
RE: Why synchronous motor with VFD
RE: Why synchronous motor with VFD
Thanks.
RE: Why synchronous motor with VFD
LCIs are thyristor based inverters. The thyristor commutation relies on the ability of the synchronous machine to produce its own internal voltage due to the rotating field of the rotor. This internally produced voltage is fundamental to the commutation process where the continuous DC link current switches seamlessly from one stator phase to the next simply by gating the incoming thyristors at the correct moment in time when the rotor is in the correct angular position. I have tried to find a decent link on the net which shows the waveforms and I have failed so far, but this topology is well illustrated in many motor and drives texts. Have a look at the FAQ in the Power Engineering forum for a couple of leads.
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If we learn from our mistakes I'm getting a great education!
RE: Why synchronous motor with VFD
This ABB link is hideously long - if it doesn't work, try searching the ABB site (shudder!). It has a block diagram and basic description of LCI drives.
RE: Why synchronous motor with VFD
Thanks once again. I am happy with the interaction.
RE: Why synchronous motor with VFD
Brochure of Megadrive is O.K.
Before two years I see one ( I think for 25MW) in Turgi Swiss. It's product!!
Slava
RE: Why synchronous motor with VFD
Those motors are Brush (FKI) synchronous motors I believe. At these ratings and speeds induction motors are limited mechanically. But there are examples of 4 pole inductiom motors up to 18MW out there, so this would be the cheaper option, if the drives are available. So, between 10 and 18MW i guess there is a case for either and a full costing would be needed.