3phase VFD drives project
3phase VFD drives project
(OP)
Hi
Ive been asked to build a 3 phase variable frequency drive controlled via a Siemens PLC as a project. As i have never done a project like this i was wondering if any one has any starting points for me to follow??
As i haven't got a clue where to kick off
Any help would be much appriciated.
Cheers
Bassbob
Ive been asked to build a 3 phase variable frequency drive controlled via a Siemens PLC as a project. As i have never done a project like this i was wondering if any one has any starting points for me to follow??
As i haven't got a clue where to kick off
Any help would be much appriciated.
Cheers
Bassbob





RE: 3phase VFD drives project
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One day my ship will come in.
But with my luck, I'll be at the airport!
RE: 3phase VFD drives project
RE: 3phase VFD drives project
You could also search for some schematics of old VFD's.
Sounds like fun.
Barry1961
RE: 3phase VFD drives project
"Our virtues and our failings are inseparable, like force and matter. When they separate, man is no more." Nikola Tesla
Member, P3
itsmoked (Electrical)
If you want to build a VFD with a PLC it ain't gonna happen.
jraef (Electrical)
Hmmm... I probably shouldn't have said transistors. With a high speed PLC you might possibly be able to make a 6 step inverter work. Sort of. Maybe not. I would never even think to try.
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RE: 3phase VFD drives project
That's like trying to build a space launch vehicle out of a coffee table...
RE: 3phase VFD drives project
But the point I was really trying to make was just what you said itsmoked. I think he meant to say he wanted to build a test stand WITH a PLC and a VFD. Hopefully bassbob will respond and clear that up, because if so, then we can help.
"Our virtues and our failings are inseparable, like force and matter. When they separate, man is no more." Nikola Tesla
Member, P3
Marke (Electrical)
Hello bassbob
electmech (Electrical)
I work at Siemens, and the PLC may be fast enough...I am not sure there. I know that there are some pretty high powered processors out there offered in standard products.
itsmoked (Electrical)
bassbob; If you really are going to scratch build a VFD(a year project) go to Microchip's site and search their app notes. They have a nice reference design.
bassbob (Electrical)
(OP)
Thanks for the info fellas.
itsmoked (Electrical)
Like I said look at those app notes. Takes a few minutes and you will see just how big the job is. You'll learn too.
Euphaz (Electrical)
Here is a 3-phase inverter program for PIC16C55 microcontroller and similar processors.
://www.pic list.org/t echref/mem ber/HB-ope ramail-885 /index.htm
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RE: 3phase VFD drives project
I do not believe that you will be able to build a VSD using a PLC as the core. It is just too slow for that type of operation. You may be able to get building blocks that comprise the "inverter"section of the VSD and use the PLC to provide the user interface. At that point, I would not say that the PLC is part of the VSD. - I would not even attemp this as the costs would far outway any advantage.
I am assuming that what you are really trying to achieve is an example of a standard VSD controlled by a PLC.
Many of the drives on th market today, have a MODBUS, Profibus or similar serial input. This can be easily coupled to a PLC with a similar serial port.
Start with the PLC, determine the serial protocol and then find a drive with a compatible protocol. NOTE Many drives use MODBUS RTU as standard and other protocols require additional modules.
If you already have a site standard coms protocol, it would make sense to use that.
Best regards,
Mark Empson
http://www.lmphotonics.com
RE: 3phase VFD drives project
This seems like a very expensive, and very difficult way to do something that has been done already (millions of times). If you are going to be working on an R&D project, you may want to consider designing a PLC program to run a standard VFD instead of literally reinventing the wheel. There is going to be a whole lot more involved than just firing transistors to accomplishing your goal. Even if you are successful, it is going to be extremely complicated to design, and I doubt that it to be able to do much but fire a series of gating signals based on an algorithm at best, and be an expensive experiment in futility at worst.
RE: 3phase VFD drives project
RE: 3phase VFD drives project
What i was thinking of doing was build a vfd from raw components and control the firing from the plc. But from the info i gathered from this forum it seems that it might be to difficult to complete??
RE: 3phase VFD drives project
A lot of VFDs use high speed digital signal processors to get through the math in time to close the loop. That's not plc territory.
RE: 3phase VFD drives project
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