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Old Nov 03, 2004, 04:03 AM
Impossible? Hah!
KreAture's Avatar
Oslo Fornebu, Norway
Joined Jun 2003
3,074 Posts
Yippee!
Brushless motor with built in logic for driving by brushed controllers!

Different people have mentioned or ventured along some of theese lines before I think, but I thought I'd make a properly named thread for it...

Basically, bu adding hall-sensors and transistors/FET's to a motor one could make it "self running" so it could be ran by a normal brushed controller.
The timing would be locked and the direction of travel and polarity would be critical, but other than this it might actually work.

Instead of 3 hall-sensors, I think a single bipolar sensor might do the trick. As long as the trigger levels of the FET's are correct the motor should be able to operate by itself.

I am aware that the losses would be higher due to the double FET stages, but all things considered I think it may still be possible to do. It would also drop the need for programming advanced microcontrollers and open up for more fun projects.

One idea is to only use the PWM of the main ESC so that one saves a FET-stage. The battery would thus be connected to the motor too, and not just feed the old brushed controller.

So, any thoughts? Any ideas on the design? I think we can do this...
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Old Nov 03, 2004, 06:03 AM
starting at RC
Zagreb,Croatia
Joined Aug 2004
58 Posts
pc fan

What about electronics in brushless PC fans ?
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Old Nov 03, 2004, 06:32 AM
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vintage1's Avatar
East Anglia, UK
Joined Sep 2002
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I do not see the point frankly.
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Old Nov 03, 2004, 06:39 AM
LT
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Stavern, Norway
Joined Jun 2001
143 Posts
Quote:
Originally Posted by KreAture
The timing would be locked and the direction of travel and polarity would be critical, but other than this it might actually work.

So, any thoughts? Any ideas on the design? I think we can do this...
I to have been thinking along these lines, but my main reason has been for getting as controler with manually adjustable timing. Mainly to be able to messure Io of motors with zero timing. Even been thinking about getting hold of a sensored controller and making some kind of 'bolt on' sensors to put on the outputshaft so as to make theese messurements.

I have not had (and will not get in the near future) any time to put my ideas into praxis though. I will be following this thread closely though.
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Old Nov 03, 2004, 07:23 AM
RIP Ric
Andy W's Avatar
Marietta, GA
Joined Jun 1999
43,312 Posts
I can't see how this could possibly work when the voltage provided by a brushed ESC is pulsed, and the switching frequency (fixed) of those pulses has no relation to commutation speed required..
..a
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Old Nov 03, 2004, 07:45 AM
Impossible? Hah!
KreAture's Avatar
Oslo Fornebu, Norway
Joined Jun 2003
3,074 Posts
Andy W
It would work because the switching is in no way relevant to the sensing in that there won't be noise issues in the same way.

Also, have you not ran a brushless computer fan with pwm? It works well...
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Old Nov 03, 2004, 09:37 AM
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Dan Baldwin's Avatar
United States, CA, Norwalk
Joined Apr 2004
2,704 Posts
I too am missing the point of having double ESC's with 3 fets in series for each phase. The motor would have to be made larger to make room for the electronics, or it would have to be mounted externally. I don't think that there would be enough difference in cost or weight between a full on BL controller, and the stripped down version that could be used with an external brushed ESC. Basically you could leave off the BEC, and the position sense op amps, but that's about it.

Dan
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Old Nov 03, 2004, 10:18 AM
Impossible? Hah!
KreAture's Avatar
Oslo Fornebu, Norway
Joined Jun 2003
3,074 Posts
None has said it would be smaller, cheaper or anything.
It would however be possible to slap together for those without programming ability.

It all depends on how you look at it. The art of non-embedded electronic design is starting slowly dying.
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Old Nov 03, 2004, 10:57 AM
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Ken-Ohki's Avatar
Someplace in Maine
Joined Jan 2004
972 Posts
Quote:
Originally Posted by KreAture
None has said it would be smaller, cheaper or anything.
It would however be possible to slap together for those without programming ability.

It all depends on how you look at it. The art of non-embedded electronic design is starting slowly dying.

Never listen to anyone who says you cant, Unless they are wearing a Badge, or refusing sex.


Ken-Ohki
"I make things do what I want them too, The Hell with what they are designed to do."
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Old Nov 03, 2004, 11:21 AM
Registered User
Upstate NY
Joined Nov 2003
842 Posts
One example of a possible application "with justification" is a brushless motor upgrade for a FP micro heli, where you already have an integrated dual ESC, BEC, Gyro, Mixer. It cost $ for new transmitter and "seperates" if you are moving up from the basic 4 channel radio gear. The typical DIY BL motor for this app is CD-Rom based and every CD rom I took apart has three of the cutest Hall sensors (that get stashed in the parts pile just in case...).
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Old Nov 03, 2004, 12:42 PM
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ZAGNUT's Avatar
Tel Aviv, Israel
Joined Jul 2004
1,902 Posts
the sensors at http://www.sentron.ch/products/senso...AngPosSens.htm might be of use?
also look through their site and see how a single sensor can be used for a 2-axis joystick...off-topic but still very neat


dave
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