Circuit design for motor power limiter? - RC Groups
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Nov 09, 2017, 06:57 PM
Registered User
Question

Circuit design for motor power limiter?


SAE International sponsors an annual Aero Design Competition for college engineering students in which the challenge is to design, build and fly an RC electric powered airplane capable of carrying a payload around a circuit. One of the limitations is that the input power to the motor cannot exceed 1000 Watts. This limitation is enforced by inserting a power limiter in series with the battery. Neumotors makes such a device.

http://neumotors.com/sae-aero-design/

Does anyone have a circuit diagram, preferably with a parts list, for such a device?
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Nov 09, 2017, 08:45 PM
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vollrathd's Avatar
Quote:
Originally Posted by aeromodel03
SAE International sponsors an annual Aero Design Competition for college engineering students in which the challenge is to design, build and fly an RC electric powered airplane capable of carrying a payload around a circuit. One of the limitations is that the input power to the motor cannot exceed 1000 Watts. This limitation is enforced by inserting a power limiter in series with the battery. Neumotors makes such a device.

http://neumotors.com/sae-aero-design/

Does anyone have a circuit diagram, preferably with a parts list, for such a device?
H'mmm, 1000 Watt Limit on motor power.

I've built a number of microcontroller controlled projects over the past 30 years, and even built some that I sold to club members. Problem is, by the time you design a circuit board, buy the circuit boards, add in all of the required parts, those parts costs add up. Especially if you buy them one at a time.

By the time you're all done, you could be approaching the single unit cost of the $70 for the Neu unit.
Nov 09, 2017, 10:51 PM
Registered User
I could buy one, but I really want to be able to adjust the power setting. Besides, I like to build things, especially things I don't know much about. So this is going to be a DIY project if someone can provide the essential information. My next door neighbor is pretty good at building circuit boards, too.
Bill
Nov 10, 2017, 12:05 AM
Registered User
vollrathd's Avatar
Quote:
Originally Posted by aeromodel03
I could buy one, but I really want to be able to adjust the power setting. Besides, I like to build things, especially things I don't know much about. So this is going to be a DIY project if someone can provide the essential information. My next door neighbor is pretty good at building circuit boards, too.
Bill
The circuitry on something like this would be fairly simple. But, if this project is inserted between the battery pack and the ESC speed control, you've got a whole can of worms between the power limiter PWM (Pulse Width Modulation) signal, and the ESC PWM signal.

I could lay out a circuit design for this type of thing in one evening. But, the software for the microcontroller to command power limiting could take a lot of hours. And, who knows if the project works properly with a Castle Creations ESC for example, that it would also work properly for an el-cheapo ESC from you know where.
Nov 10, 2017, 10:45 AM
Registered User
Thanks for the words of warning; closed loop systems tend to generate surprises. Is there a totally analog solution to avoid the software programming issues?
I would still like to try even if it ends in failure - I've built some unusual planes that were real dogs.
Nov 14, 2017, 03:26 PM
homo ludens modellisticus
Ron van Sommeren's Avatar
You could ask/search the F5B & F5D wizzzz-bangg gang in the High Performance subforum. Limiters (energy? power?) are mandatory in those competitions.
Some (all?) of the players/designers you can find in a.o. these threads
Limiter Tester
to limit, or not? F5B watt limits
&
more limiter threads

Vriendelijke groeten Ron
Last edited by Ron van Sommeren; Nov 14, 2017 at 05:42 PM.


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