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Topic: +, -, GND (Read 2 times) previous topic - next topic

yosler

majenko:    I'm not exactly positive that the other one is ground or -. What it could be? - I don't think it's for noise reduction/safety etc. Probably something to do with some other function; backwards, maybe a command line or an emergency power line, I don't know. Or, like a lot of people were saying, maybe a 3 phase sensorless motor?

In regards to the 3 phase motor, I Wikipedia-ed it and came up w/ http://en.wikipedia.org/wiki/Three-phase_electric_power
If don't really understand what a 'phase' actually is, that would help.

retrolefty: Thank you for helping to clarify it. Correct....... I have a 30mA ESC. Remember, I have a 1000kv 400xt brushless motor. www.hobbypartz.com/40tyoubrmo.html  I also have a BEC.
I'm 13 and I'll frequently be wordy, not writing to the point.
But don't worry, I know somethings about electronics.

majenko

A three phase brushless DC motor, which is what you have, consists of three coils of wire arranged in a triangle, with one wire attached to each point of the triangle.  Different signals are applied to each coil to create a moving "wave" of magnetism.  This wave drags the magnet around to turn the motor.

You cannot drive a 3-phase BLDC motor directly.  Instead, you need to create three AC waveforms with each wave offset by 120 degrees from each other.
Get 10% off all 4D Systems TFT screens this month: use discount code MAJENKO10

Nick Gammon


If don't really understand what a 'phase' actually is, that would help.


Here's one description:

http://en.wikipedia.org/wiki/Phase_(waves)

In essence, for (say) a sine wave, the phase describes how "far along" the wave you are at a particular moment. Electricity distributions systems usually use 3-phase power, the idea being that the 3 phases will roughly cancel out when added together, reducing the size of the "ground return" wire that is required.

retrolefty

Quote
Electricity distributions systems usually use 3-phase power, the idea being that the 3 phases will roughly cancel out when added together, reducing the size of the "ground return" wire that is required.


LOL Best to stick to software Nick.  ;) 3 phase electrical distrubution systems have several advantages over single phase in higher power systems, but none of those advantages match your guess. The power from each individual phase will actually add, not cancel, to the total power being consumed by the load(s). If a 'ground' wire even carries working current depends on if it's a delta or star Y 3 phase system.

Lefty


Nick Gammon

Yep, I'm no hardware expert. :)

However: http://en.wikipedia.org/wiki/3-phase_power

From that page:

Quote
The phase currents tend to cancel out one another, summing to zero in the case of a linear balanced load. This makes it possible to eliminate or reduce the size of the neutral conductor; all the phase conductors carry the same current and so can be the same size, for a balanced load.


I said "the 3 phases will roughly cancel out when added together", Wikipedia says: "The phase currents tend to cancel out one another, summing to zero".

Isn't that the same thing?

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