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Apr 05, 2012, 08:07 PM
Heli addict
Quote:
Originally Posted by vladz
That what I was thinking about... looks like top current is 3 times more then with OEM firmware.
Edit: in case of good source with low impedance this peak can fry coils.
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Apr 06, 2012, 11:10 AM
Quad Whisperer
Quote:
Originally Posted by jesolins
Hi Rolf,
Thanks for the great ESC performance data! It is certainly easy to see the differences between the firmwares.
Al from Hoverfly started yet another thread on this here. Your insights and repeatable testing data would be an asset there too. https://www.rcgroups.com/forums/show....php?t=1620724
Cheers,
Jim
Quadrocopter and Tricopter Info Mega Link Index
He tests the response of ESC+motor, I only test the response of the ESC alone because that was harder to judge by just looking and testing things.


Quote:
Originally Posted by simonk
Hi, kapteinkuk! Incidentally, what is the peak of that current when scaled from shunt voltage to actual Amperes? Cheers
The shunt is 0.1 Ohm, the peak is close to 6A.

Quote:
Originally Posted by vladz
Edit: in case of good source with low impedance this peak can fry coils.
The coils+stator have a large thermal mass, so I do not think that is an issue.

But it is of course wise to increase the rating of the ESC, both because the increased peak currents and extra heat generated due to the increased PWM frequency.

In my opinion I think the reason for the input filter is to avoid large peak current. I previously thought that the filter was to avoid rapid acceleration of the motor causing loss of synchronization.

Just now I have a large HK Donkey motor running on my table, slowly and silently. I am happy that the annoying 8 kHz whine is gone!
Apr 06, 2012, 02:39 PM
Heli addict
Quote:
Originally Posted by kapteinkuk

In my opinion I think the reason for the input filter is to avoid large peak current. I previously thought that the filter was to avoid rapid acceleration of the motor causing loss of synchronization.
I think you are right. Once motor is going ESC calculates correct phase using back EMF. But bigger peak energy calls for increase ESC rating.

Well, when we are running 490Hz update cycle, would it make a difference if ESC reacts instantaneously or say with ramp-up time of 10-20ms?

And we don't counting motor+prop inertia... What do you think?
Apr 07, 2012, 12:17 PM
Quad Whisperer
Any ramp up time will give a lower peak current.
Apr 09, 2012, 10:41 AM
hacker
Quote:
Originally Posted by kapteinkuk
In my opinion I think the reason for the input filter is to avoid large peak current. I previously thought that the filter was to avoid rapid acceleration of the motor causing loss of synchronization.
I still think it's actually for both reasons. There are some motors where the coil demagnetization can take so long (with a large current spike) that it can fool the zero-crossing detection and lose synchronization. I see this with some hard drive motors, the MT-3506, and the 24g hextronik motors, for example. It seems it might be necessary to do something special in these cases, but most motors seem to be fine with jumps from low to high throttle. The problem comes up more often at higher voltages, too.

http://0x.ca/sim/esc/timing_loss_fix/
Apr 10, 2012, 04:27 PM
Quad Whisperer
Ok, I think you are right.
Apr 10, 2012, 04:53 PM
saabguyspg's Avatar
ummm I am hoping that this will not happen on my MT 4008's 600kv... any thoughts on that?

steve
May 16, 2012, 08:58 AM
Quad Whisperer
I have tested the HK10A. Response time of 200ms (10 filter steps).
It is quite bad. It needs a firmware upgrade
Mar 16, 2013, 06:17 AM
Registered User
holco's Avatar
What do you guy's think about this?

Full size link: http://www1.picturepush.com/photo/a/...SC/400Hz-1.jpg

Nov 09, 2013, 12:28 AM
Quadaholic
--Oz--'s Avatar
First post here, thread seems to have slowed down.

Now step forward in time (to today). How does the "newer" closed loop ESC's (like ultraESC or STM32 esc) compare (ramp up and down times), are they worth it? Clearly the closed loop has an acro advantage.


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