AivisJ
Posts: 1
Joined: Mon Dec 03, 2018 7:35 pm

Controlling 2 AC motors with power 2kW for each

Mon Dec 03, 2018 8:13 pm

Hello

I am very new for raspberry PI. But I have to make system where I can controll 2 AC motors. (220VAC)

I hope you can give me information about things what I need to do that.
The main idea is that both motors will start at same time, but the load and forces that brakes them could be different. When motors start to spin their torque have to be low, but then it must increase until predefined current reached and then cuts off. And I have to monitor current drawn by motors.

I have seen a video where it is done with dc motor and much lower power. (https://www.youtube.com/watch?v=_MCxxdKj5os)
I'm sorry couldn't find any video with raspberry PI! :(

So power for each of motor would be 2kW in my case. So I need much more things than DC setup.

For starting motors at the exact same time I could use motors with build-in encoders, right?
For controlling motors is there any other option without VFD?
What things I have to consider?
Maybe better 24 or 48 V DC motors? But then I need some transformator...

Once again, I am new for all this stuff, but I hope, that you could help me! Ask me questions I could try to answer them.

User avatar
Tage
Posts: 287
Joined: Fri May 24, 2013 2:29 am
Location: St Thomas, Ontario Canada

Re: Controlling 2 AC motors with power 2kW for each

Sat Dec 08, 2018 10:00 pm

you probably have found out that this forum is not the best place to get advice on this type of questions, but I can respond with my thoughts..
I would use two motor drives that are powered from single phase 230V and drive standard asynchronous three phase motors. I would not use dc motors, because I think that the cost of purchasing say a 4kW ac to dc converter that delivers 48Vdc to two 2kW dc motor drives plus motors will be too high.
My guess is that using standard 2kW three phase asynchronous motors and two 2kW ac drives is much less.

Depending on the application requirements, you may get away with using say 1.5kW drives, if you do not need to run full 2kW continuously.

pcmanbob
Posts: 4554
Joined: Fri May 31, 2013 9:28 pm
Location: Mansfield UK

Re: Controlling 2 AC motors with power 2kW for each

Sun Dec 09, 2018 12:25 pm

Controlling two 220VAC motors is no project for a beginner, to control that sort of power and rotating machinery you need to be qualified not only as an electrician but probably in electrical and mechanical design as well.

There are lots of things to consider in the design related to electrical safety and mechanical safety, not least that in the event of any component of the design failing the system must fail safe and stop everything safely.

I would never consider a pi a suitable device for controlling rotating machinery operating at these voltages because you can't predict how the pi would fail under all conditions.

Depending were you live there may also be legal ramifications with regard to what you want to do that could in the event of an accident, death or destruction of property, land you in trouble with the law.

For that reason I don't think you will find anyone with any sense willing to give you any detailed instructions on how to do such a project on this forum which after all is only a computer forum and not an electrical/mechanical design forum.
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