Electric kart 10/5kw ac synchronous motor

[thegala]

Well in the video he is saying negative current. And yes a electronically commutated means that you are reverseing current or voltage if you what to be specific. So you get a AC current which proves my point.

 

[itsid]

Ah.. Now I see your misconception!

No reversing polarity is NOT making that an AC motor.
EVERY simple brushed DC motor is actually reversing the polarity at least twice per revolution.
that's COMMUTATION!

'sid

 

[thegala]

I know but that is also reversing a current so you get an AC current shape.

 

[thegala]

That commutation is actually also done in every AC motor just here you are doing it with some electronic you can't just use a DC you must reverse it.

 

[thegala]

Ah.. Now I see your misconception!

No reversing polarity is NOT making that an AC motor.
EVERY simple brushed DC motor is actually reversing the polarity at least twice per revolution.
that's COMMUTATION!

'sid

Yes you control a motor with a dc current but let's imagine in this way what sort of a current motor see. If you put a oscilloscope on A and ground what type of current wave form you will get.
Sorry for so much split posts.

 

[itsid]

Good Lord,
you're the densest of brick walls I have ever had the displeasure of conversing with.

I

'sid

PS And that means your thread will be ignored from this moment on, call your pig a sheep I don't care at all...

 

[thegala]

I don't know what to say. You also are a tuft nutt. I realy think that you have knowledge on this topic but lets say you have more misconceptions then I do.

Well I must say I am really disappointed about ignoring but what can I do about it. Nothing so I don't care.

And thank you for nice chatting.
(not ironic)

 

[drm]

now that the soap opera is over, lets see some design sketches or pics when you get them.

 

[thegala]

Picture of motor and controller.
Just experimenting before chassis arrive and we build our own controller.

 

[HelloYOU]

Motors produce Back EMF, that much you will agree upon.
Now, a DC motor creates a square wave
(I think we can accept that a single phase potential difference is a infinitely wide square wave)
And so does a BLDC motor it produces a square wave,
or well let's say trapezoidal wave that's a better match; still square'ish .

An AC motor on the other hand produces sinusoidal back EMF.

And since motors like to be powered in the same way they produce back emf, that's the optimal way to excite them.

Actually ALL motors produce AC, even commutated DC motors. The DC output is the result of the commutator being switched at the moment before current reversal. IF you removed the commutator on a brushed DC motor and replaced it with slip rings, then you get AC. Likewise, brushless DC motors DO produce AC if you turn them like a generator.


I suggest you buy an Oscilloscope to see for yourself...

That's what your wikipedia article means with "does not imply sinusodial..."

There are many mechanical as well as electrical differences between the two.
the rotors are different, the way they like to be powered is different..
But most important of all:
An AC motor has all three stator coils ALWAYS ENERGIZED,
which you simply cannot do with a BLDC.

So please, if you build your controller, make sure you build a Brushless DC motor controller;
Do not build an AC motor controller not even an brushless AC motor controller, it will not power your motor.

'sid

Not all AC motors are 3 phase. Single phase motors also exist. Many modern brushless DC motors are also 3-phase and come in Wye or Delta configuration and can be ran on sinusoidal current. In fact, I work with industrial Brushless DC servo drives and they use sinusoidal current that results in a cooler running motor and smoother speeds.

The output drives for 3-phase brushless DC motors and AC motors is the same. The only difference is that DC is postion and AC is velocity and current. With simple software changes in the micro controller I could make a brushless DC controller work with an AC induction motor.

Finally, the term brushless AC motor is not a correct term. AC induction motors have always been brushless since 1888. We do not use that term for AC induction motors. We do however say brushed AC motor if it is the slip ring type or the universal motor type that can run both AC or DC. We say brushless DC motors because DC motors when first created, were not brushless and they are still created with brushes also. It's a double negative to brushless AC induction motor. That's like saying not-not since by saying induction (think transformers) already means brushless and so you are saying brushless, brushless AC motor. Saying AC induction motor will suffice.