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How to draw 220V motor


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#1 Rookie

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Posted 19 March 2012 - 01:03 PM

Hello Netizens, I would like to control my solar system with a microcontroller. I know how to measure temperatures (more important: their differences), but I do not know how to control my pumps. I need circuitry to steer motors for 220V with about 100 Watts. My current controller uses PWM with 2-10Hz and I want to use this technique too. Therefore I cannot use a (mechanical) relay. Tnx in advance!

#2 Rookie

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Posted 19 March 2012 - 09:05 PM

Well, I learned that I should use a MOC2040 etc. Anyone has used this to drive inductive loads (i.e. motors) ? Greetings - Rookie

#3 nakchak

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Posted 28 March 2012 - 08:32 PM

For large inductive loads I have used industrial inverters depending on your needs you can pick a soft start up quite cheaply. You also can use it to tailor pump speed etc. They typically have an rs232 interface to control the duty cycle frequency and peak to peak voltage which with a couple of opto isolators should be pretty easy to interface a netduino with.

#4 Magpie

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Posted 29 March 2012 - 12:43 AM

I am not sure how your current controller works but to do speed control of an AC induction motor you will need the equivalent of a Variable Speed Drive (VSD). These are prohibitively expensive, so you might have to look at a DC motor. If you have any details of your current motor controller, I would be interested to see what it does.
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#5 Bill E.

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Posted 30 March 2012 - 12:34 AM

Netizens! That's clever. I love it - we should cap on that phrase.

Rookie, exactly what do you want to do with the 220V (AC I presume) 100W motors? Control their cycle time or speed? Cycle time can be done with triacs (for a reasonable duty cycle period like on for 10 seconds off for 10 seconds) but if you want speed? Now that's more difficult. Magpie hit it on the head that if you want to control the speed of the motors. PWM is all about effective energy delivered to a load. Using PWM with AC (50/60HZ) just doesn't compute. You need DC motors to work with PWM - on vs off time.

A solar system, I would think, doesn't need milisecond or even second control. If I were you I would think about a NUCH hegher repetition rate line MINUTES control of the pumps. Simple monitoring works then.

Peace,
Bill




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