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Author Topic: Brushless Basics  (Read 77892 times)

roger

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Re: Brushless Basics
« Reply #100 on: July 19, 2010, 06:24:05 PM »

Thanks for your prompt response Nick. That all seems quite logical.

However, I'm not sure your car analogy really fits here. While my car has brakes, the "brake" on a boat is throwing it into reverse. I certainly wouldn't want to blow up my esc. (In fact I'm still gathering the kit together as I haven't used brushless motors before, so I don't actually have the bits yet for even a controlled bench-test.)

Since the brain (such as it is!) is more readily available than the cash at the moment, I guess I need to drag out my thinking cap from the bottom of the scraps box and dust it off.

Electronically I suppose I'd monitor the signals in the three power leads and select the appropriate moment (presumably when there are no signals) to do the AB - BA swap. I guess this is something like the way reversing ESC's work anyway, so I needn't try to re-invent the wheel.

[Going off at a tangent, did you read about the guy who built a 4.50 (about A$8) toaster from scratch - ie metal ores, crude oil etc. It took him six months, cost 2000 (labour not included) and blew up after thirty seconds operation!]

Mechanically, I guess I could rig up an interlock that allows Andrew's reversing microswitch(es) to throw only when the propshaft is stationary. Of course it would have to work both ways - ie from backwards to forwards as well. Maybe it would be better to stick with a one-way only motor and hang a couple of reversing buckets off the Kort rudder.

For my next tug (even though I've barely started this one) I fancy fitting an asimuth drive. Adam's setup in Reply #10 of Brushless Motors in Tugs - http://www.modelboatmayhem.co.uk/forum/index.php?topic=22743.0 - looks really neat.
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malcolmfrary

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Re: Brushless Basics
« Reply #101 on: July 31, 2010, 09:39:24 AM »

The logical way to avoid cooking the motor/ESC when reversing is to have a "soft" response to the stick.  That way, the mechanical bits have a chance to keep pace with whatever the electronics are doing.
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sailorboy61

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Re: Brushless Basics
« Reply #102 on: July 02, 2012, 02:43:45 PM »

Following the links reading through the posts, I noticed this:

http://www.youtube.com/watch?v=mbU-uOdKgOc&feature=related
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Martin [Admin]

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Re: Brushless Basics
« Reply #103 on: January 21, 2013, 07:53:52 PM »

 
On Youtube - RC BASICS: What is KV? http://youtu.be/IP4PFq6u7wg
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wayne quigley

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Re: Brushless Basics
« Reply #104 on: May 01, 2013, 09:38:26 PM »

8sorry am I missing some thing
inrunners  have a fixed can and the internals spin just like a brushed motor.
outrunner have the intenals fixed and the can spins???the problem is i have been searching for motor for a 46" fairy huntsman and all the outrunners i have seen seem to have a fixing bracket fixed to the can and the cable attached to the can.
where am i going wrong
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malcolmfrary

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nick_75au

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Re: Brushless Basics
« Reply #106 on: May 02, 2013, 10:30:35 AM »

One end of the "can" is fixed, this is your mounting point the same as a brushed motor and where the wires come out, the rotating can is more like a rotating cup and the "lid" stays still.


In both cases its the magnets that rotate while the windings stay still.


Nick
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wayne quigley

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Re: Brushless Basics
« Reply #107 on: May 02, 2013, 08:23:51 PM »

thanks i have beeen on YouTube and seen how they run now all clear when you see them in action.
also is there any way of not having to input Verification questions for each post,a right pain in the rear
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Tug Fanatic

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Re: Brushless Basics
« Reply #108 on: May 14, 2013, 01:39:09 PM »

Brushless motors come in a variety of diameters & lengths. With brushed motors there was generally much less choice but can diameter was a good indicator of prop size compatability.
 
With a pair of brushless outrunner motors if one is short & wide but the other is long & thin & they both have the same kv & maximum current rating would you know which was the better motor for particular applications? Do the same rules apply?
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Martin [Admin]

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Re: Brushless Basics
« Reply #109 on: August 31, 2015, 08:05:13 AM »

 
RC BASICS: What is KV? :  https://youtu.be/IP4PFq6u7wg
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Martin [Admin]

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Re: Brushless Basics
« Reply #110 on: August 31, 2015, 08:31:00 AM »

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tugboatg

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Re: Brushless Basics
« Reply #111 on: September 01, 2015, 04:11:46 AM »

Any help with Brushless outrunner motor to fit MFA 2 to 1 belt drive ?  39 inch twin screw tug
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andrewh

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Re: Brushless Basics
« Reply #112 on: February 23, 2016, 04:34:00 AM »

Hi, tugboatg


The MFA drive is made to fit any and all motors of size 540, 550, 600 and many more with similar numbers, and has been made to fit a S700 with a little machining


So the basic answer is any brushless with 540 front-end fixings, or could be modified to it.  I suspect the small gear is bored for the 540/600 shaft ,which is 1/8" but no doubt you could bore it a little bigger


The simplest answer is probably the worst - many of the car inrunner brushlesses are made to fit the 540 mount - but they are the very wrong motor for a tugboat, as they are generally high-speed, low torque.


Remember that in the brushless description the first figure is the rotor diameter (EG a 3560 1050kv motor is 35mm diameter) 
Since a  540 is 35.8mm diameter with 2 fixing holes at 1" centres any outrunner with a diameter 35 mm or less should fit onto the face of the belt drive


For a tug, I feel that you probably want max Torque and low revs, so this equates to a low Kv
(altho' of course the belt drive is more than halving the prop revs (my memory says its a 2.3:1 ratio)


hope some of this helps
andrew
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Onetenor

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Re: Brushless Basics
« Reply #113 on: October 30, 2018, 05:32:53 AM »

Seen this?===https://www.designnews.com/automation-motion-control/small-controller-delivers-brushless-dc-motor-efficiency/131652937959694?ADTRK=UBM&elq_mid=6234&elq_cid=1081809
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malcolmfrary

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Re: Brushless Basics
« Reply #114 on: October 30, 2018, 09:13:56 AM »

https://www.designnews.com/automation-motion-control/small-controller-delivers-brushless-dc-motor-efficiency/131652937959694?ADTRK=UBM&elq_mid=6234&elq_cid=1081809
Manages to say a great deal without actually telling anything useful.  What numbers I understood indicate a fairly anaemic control that needs something like an Arduino to control it, rather than being something that plugs into a radio.
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andrewh

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Re: Brushless Basics
« Reply #115 on: October 31, 2018, 05:05:45 AM »

Thanks, John and Malcolm
Its a Maxon evaluation unit and, as the article says, is aimed at control.  It mentions pick-and-place as the type of thing that it might be used for. 
Maxon are experts in precision tiny motors - one of the first sources of coreless motors in the 1980s, and not cheap


Interestingly; the photo is not very related to the article  - the illustration is many times larger than the mentioned size of 20.38mm x 24.2mm
andrew
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