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Old Jul 02, 2005, 02:51 PM
Checking the wind
kansascloud's Avatar
Aubry Township, Kansas South of KC.
Joined Jan 2002
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Help! Brushless Motor running BACKWARDS

Please help! I'm installing a Balsa Products BP 21 on my Slow Stik. (my first burshless setup) I'm also using the BP 18 amp esc. I installed all new deans conectors making very sure everything is white to white and red to red. Everything works great but the damn thing runs backwards!!!

What do I do?

Thanks for your help!

Mike
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Old Jul 02, 2005, 02:55 PM
Registered User
Northern Ireland
Joined Jan 2005
258 Posts
Quote:
Originally Posted by kansascloud
Please help! I'm installing a Balsa Products BP 21 on my Slow Stik. (my first burshless setup) I'm also using the BP 18 amp esc. I installed all new deans conectors making very sure everything is white to white and red to red. Everything works great but the damn thing runs backwards!!!

What do I do?

Thanks for your help!

Mike
Just swop any two motor to esc wires.

Make it red to white and white to red and leave the other one alone

Do NOT swop the battery to esc wires or it will be toast
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Old Jul 02, 2005, 03:30 PM
PGR
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United States, CA, Costa Mesa
Joined Jun 2004
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Quote:
Originally Posted by raymcm
Just swop any two motor to esc wires.
Yup! A brushless motor doesn't know "backwards" or forwards. It only knows clockwise and counterclockwise and it doesn't prefer either one. To change rotation, simply switch any 2 of 3 wires between motor and ESC.

It's intresting to note that you change the rotation of industrial 3-phase motors the same way.

Pete
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Old Jul 02, 2005, 04:49 PM
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UK
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Brushless motors are 3 phase AC motors, exactly the same as Industrila 3 phase AC motors. The controller converts from DC to AC.
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Old Jul 03, 2005, 12:32 PM
Destroyer of Cell's!!!
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matfield,tonbridge, kent,england
Joined May 2001
363 Posts
can i just jump in here the brushless esc is actually pulsed DC and not true AC in my knowledge of the subject the esc merely mimics AC and does not acually make it
regards
nasa
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Old Jul 03, 2005, 12:52 PM
Marion
USA, NC, Hillsborough
Joined Oct 2003
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The only diference, seems to me, is that the ESC makes three phase square waves, and your house current is sine wave. Right ?? The ESC output is still AC in my book.

Marion
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Old Jul 03, 2005, 01:08 PM
Destroyer of Cell's!!!
nasa_steve's Avatar
matfield,tonbridge, kent,england
Joined May 2001
363 Posts
hi marion
no believe me i am by trade an electrician and pulsed dc is definately not ac. in an ac supply there is both positive and negative within the supply. dc is direct with no negative element in the supply. pulsed dc is literally supply on supply off. ac is not switched it moves to positive and then negative by equal amounts hence the sine wave output on an oscilloscope the baseline on the ac output is is in the middle on a dc output it is at the bottom.
hope this clarifies a bit i can go further but then you'd end up being bored silly by the science.
regards
nasa
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Old Jul 03, 2005, 01:27 PM
I don't want to "Switch Now"
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Toronto (Don Mills), Canada
Joined Dec 2002
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Since Mike's question has been answered, I will dive in here as well.
Motor terminology is not carved in stone, but is by convention.

The vast majority of industrial motors are 3 phase AC induction motors. No magnets, only coils. Completely different animal.
They always spin slightly slower than the rotating field. Higher load results in lower speed, but the input frequency is always the same.
Single phase induction motors are an offshoot of the 3 phase ones.

Another type of industrial motor is the 3 phase synchronous motor. It is normally made with slip rings and field coils in the rotor, where we use permanent magnets.
They always spin at the same frequency as the AC field.
As load is applied the phase angle between the rotating field and the motor increases increasing the torque.

The closest thing to a DC brushless motor is the AC servo motor. The construction can be almost identical.
What is different is the driving circuits. They generate pseudo sine waves.
Torque is controlled by the phase of the sine wave relative to the motor rotation, just like the AC synchronous motor. This is called vector control.

Brushless DC motors vary the torque by varying the applied voltage only.
The phase is held fixed either by the sensors or by the sensorless controller. The waveforms are not pseudo- sine waves, but trapezoids.
Pat MacKenzie
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Old Jul 03, 2005, 03:29 PM
homo ludens modellisticus
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near Nijmegen, Netherlands
Joined Feb 2001
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Pictures of brushlesss waveforms: http://www.torcman.de/peterslrk/SPEE...l#Anker1591256
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