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View Full Version : [Question(s)] 3-phase motor, how to control?



gman1881
05-30-2013, 11:17 PM
4770so I found a broken open garage door opener at the good will and was this big motor sitting in it and was hopeing I could use it to make a motorized bike with it but I after blowing an atx power supply found out this is no dc motor this is a 3-phase motor(explains the third wire) and I cant find anything online as to how to invert dc to ac and power to power this big o' motor. so im turning to the forum I come to with all my ridiculous questions and projects for some help. anything educational would help ive got nothing helping me to use this motor

Th232
05-31-2013, 12:45 AM
I hate to be a bucket of cold water on this, but...

How do you know it's 3 phase? Generally 3 phase is connected to the mains lines and limited to industrial equipment that requires a lot more power than a garage door opener of that size (judging by the wire and spade terminal size). The three wires might very well be positive, negative and a control/brake wire, or use two of the wires to run it one way, another two to run it the other way. If you measure the resistance between each of the leads what do you get?

Also, I think the motor requirements for a garage door opener and a bike are very different so I'm not so sure how well this'll work even if you get the motor running.

Edit: Additional thought: was there by any chance a large capacitor in the door opener with the motor? If so then I'd consider that to be a vital part of the setup.

TXBDan
05-31-2013, 08:16 AM
It's probably a BLDC. You can verify by ohming out the three wire taps. There should be a similar coil resistance if you ohm across A to B, B to C, and A to C. (look at the Y or Star config schematic in the wiki below).

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

You can control it it lots of ways from three toggle switches, to a microcontroller switching an H bridge, to an off the shelf industrial controller. :)

If you have a power supply, you can energize each coil one at a time and see how it moves to get a feel for how it chugs around in a circle.

escott76
05-31-2013, 08:38 AM
How about a large bldc airplane or other hobby type controller? I'd also echo what others have said about checking to make sure what kind of motor it is. Having tried to reuse many motors over the years, some sucessful and some not, I can honestly say without decent docs to begin with you are already looking at diminishing returns.
I would also say that if I were building a garage door opener a bldc would not be my first choice unless money were no object. That would make me think its likely not a bldc, again without docs who can say?

jwatte
05-31-2013, 12:19 PM
Have you opened it up yet? If not, that's probably the next step!