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[on:]

Greetings earthlings,

I'm a newbie here, so I'll give you a bit of who I am, and what I'm doing. I graduated from mechanical engineering in 2008, which means the electronics course I took in university was a good 8-ish years ago. With all the other stuff I was studying, it's all quite foggy in my brain now. I'm not tremendously strong in the electrical department, but I make up for that in curiousity and research. What makes my journey easiest, is having a good, simple source of information. I'd like to learn some essential induction motor control - I have spent the last few weeks (and months previous) studying a good portion of the material on this forum, other sources, youtube (I like to SEE it), wikipedia, and I'm soon to plow through my old electronics text to see if I can get it sorted. But I need a helping hand (and hopefully won't get a "SEARCH NEWB!" response). I purchased a Mega a few days ago.

The plan is simple; to send power to and from induction motors (all induction motors have hall effect RPM sensors). I can start with BLDC, but the eventual project will be induction.

Phase 1: I'd like to be able to initially power an induction motor
Phase 2: then I'd like to supply mechanical power to the induction motor, and charge, say, a battery bank.
Phase 3: Thirdly, I'd like to swap power between two induction motors - swapping electrical for mechanical power and back again. That is, crank one with mechanical power, and have the other spin and vise versa.

logically, I'd say that phase 2 and 3 should come very quickly on the heels of a successful Phase 1.

My number one criteria is efficiency.

Any good resources or pointers?

thanks,
Sim

[Reply #1 on:]

3 phase AC motor?

[Reply #2 on:]

sorry yes, 3-phase induction.

Sim

[Reply #3 on:]

http://en.wikipedia.org/wiki/Induction_generator

[Reply #4 on:]

Thanks retro; there's a good chance that if I'm an engineer, I've read the brief wikipedia page on induction generators. I'm more curious about how to build the power electronics, and if anyone has schematics/diagrams of proper controllers.

[Reply #5 on:]

My three phase induction motors don't have hall effect sensors,  so your assumption that they all do,  is misguided.

To control an induction motor over a range of speeds,   you basically need to create your own variable frequency,
three phase supply.  First you create DC,   then you have a 6 way H bridge type circuit to create the variable
frequency three phase AC.   You can buy a module to do this,  which you can control with your arduino in various ways.

For low power,  you can use devices designed for electric model planes.

[Reply #6 on:]

Trying to use an induction motor as a generator can be rather complicated and tricky.

To work,  it needs to be connected to a proper three phase supply.  If you connect a three phase
motor to the regular utility 3 phase supply  and then try to drive the motor faster than the nominal
speed,  it will push power back out into the supply network.   

But to use it as a generator on its own,  it won't work.   And your 3-phase ESC  or  variable frequency
drive circuit is going to have issues trying to accept power backwards from the motor,  unless designed
with that purpose in mind.  The diodes will all be facing the wrong way.

To convert mechanical power from a windmill or something into electricity,  there are several ways
you can do it,  but an induction motor isn't really very practical.

[Reply #7 on:]

or low power,  you can use devices designed for electric model planes.

That depends how you define low power:

90Amp ESC

http://www.giantshark.co.uk/seaking90a-brushless-boat-version-p-405848.html

[Reply #8 on:]

all MY induction motors have RPM sensors for feedback (I specified this in case they were needed). I'm aware that not ALL do.

The end goal is to have nothing in DC (other than perhaps the arduino signals... if they need to be?). That is, if I mechanically spin an excited induction generator/motor, I should be able to form 3-phase power out. This 3-phase power should power an induction motor, no? I should be able to control speed and torque by modulating the frequency of the signal, no?

Very simply, I'm building a flywheel and motor pair. spin the flywheel up (using household AC power), send power from the flywheel to the motor, and then back again. Control the speed of the motor with frequency modulation (I assume). Is there an elegant solution for this?

thanks,
Sim