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Topic: controlling an induction motor. (Read 814 times) previous topic - next topic

lash

hello everybody..First of all please don't mind my English it's not good.
I have a single phase induction motor used in a washing machine..when i connect it to house power supply(230v 50Hz) it can rotate at a constant speed clockwise or anti clockwise.As i know the basics of single phase induction motor I understand about that.. But now i need to use it on a project and i want to control the speed of the motor.And i need it to use from a DC power supply...I there any way to do it with a Arduino uno...I think Analog write  wouldn't work on a AC motor of course   . please correct i am wrong or tell me a way to do that.And i need to do it with a arduino uno only..Thank you.

MarkT

I've not seen that before - what model/part/datasheet?  3-phase induction motors are commonly used,
as are universal motors and direct-drive multi-pole brushless.
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mauried

Whats the motors power rating, and is it a capacitor start motor or some other type.
What sort of project, ie whats the motor going to drive.
Single phase induction motors are very hard to speed control as they can easily stall when you try and slow them down.

MarkT

Indeed we want full details of the motor, not your guess as to what it is, which means
any part numbers, datasheet, photo of nameplate, photo of motor and its connection
block and any other information you have...
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allanhurst

If it's a standard  'squirrel cage ' motor, you will have to generate a variable frequency
with 250vac  capability with 2 phases 90 degrees apart, each of several hundred watts capability.

Not trivial. There is no cheap trick to do this.

Buy a 3-phase motor and variable frequency controller.  For 1-3 HP cost you about £300.

regards

Allan.

MarkT

Lets wait and see what the motor really is first!
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lash

#6
Mar 29, 2016, 12:41 pm Last Edit: Mar 29, 2016, 12:48 pm by lash
Here is the name plate of the motor.
I can't upload a much clear one sorry for that...I think the information you need is in here..Thank you all for replying..

MarkT

#7
Mar 29, 2016, 10:29 pm Last Edit: Mar 29, 2016, 10:30 pm by MarkT
Well it is a capacitor-start one-phase induction motor in fact, but with the capacitor switch brought
out so you can start it in either direction I think - that would mean the two windings should
measure to have the same resistance.

You could probably combine it with a single-phase V/f controller and a relay to be able to run
in either direction, so you'd need a V/f controller that has DC input (I think most take
ac or dc on the input anyway, since the first component is a bridge rectifier), and some way
to electronically control (not just a knob on the front panel) it, such as 10V or current loop
analog input.

There will only be a limited range of speeds possible because the capacitor switch will drop in
at lower speeds, and it probably isn't thermally rated for both windings being on together
for prolonged periods (well I would worry about it)
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lash

Thank you MarkT...I don't have much experience with these things i will try to figure it out with your explanation.. can you explain me what is gonna happen if we change the input voltage or the frequency  ...I think frequency will change the speed and voltage will change how hard it can operate..I think you understand me...am i correct?

mauried

#9
Mar 30, 2016, 05:40 am Last Edit: Mar 30, 2016, 05:45 am by mauried
What is the motor driving ?
The motors load will ultimately determine whether this idea will work or not.
Slowing a single phase motor down with a VFD is difficult , as the motor current goes up as the frequency goes down, so you must be careful not to burn out the motors run winding.
As MarkT has indicated, if you slow the motor down too much, the start winding will be switched in, and the motor current will increase substantially.
Start windings arnt intended to be permanantly energised,so you will need some mechanism in place to prevent this from happening.
Would be far easier to use a 3 phase motor, or a brush type universal motor.


lash


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