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Author Topic: ESC setting that affect amp draw?  (Read 9472 times)

Online Dennis Toth

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ESC setting that affect amp draw?
« on: August 07, 2014, 10:13:22 AM »
Guys,
One of the issues we have with ECL is matching our battery pack to the motor/prop package for each airplane. The packs are only available in certain step capacities. If you need 250 mah more you may have to jump to the next pack size up which may be a big weight penalty. Other option is to reduce the prop load which could reduce performance. The third option is to manage the ESC settings. I have done some bench tests and it seems that gain and motor timing setting have the biggest impact on amp draw also PWH to a lessor degree. I don't know why they do or which one you should adjust first.

Can someone with a background in these controllers give a little explanation of how each item impacts amp draw. Which one is most effective in lowering draw? Which one helps response time?

Best,         DennisT

Online Dennis Toth

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Re: ESC setting that affect amp draw?
« Reply #1 on: June 08, 2015, 05:31:59 PM »
So its been almost a year over 3100 hits on this post and no one has a clue about what ESC settings will impact the amp draw. There has to be someone on this forum that knows what's going on and how we should approach this.

Best,         DennisT

Offline Tim Wescott

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Re: ESC setting that affect amp draw?
« Reply #2 on: June 08, 2015, 08:01:40 PM »
This would be a good question to ask Castle, because it's going to vary from manufacturer to manufacturer.

I can give you some generalities, but I'm not a user of ESCs -- I'm a circuit designer who has designed brushless controllers similar to ESCs.  I could probably design an ESC (at least one that'll turn a motor -- maybe not one that's worth spit).  For going out and having fun, I fly slime (this is because after you add the sound system and the smoke generator, electrics are way heavier than slime).  So I have to make some assumptions which may or may not be correct.

So, here's what I know:

"Gain" probably means the proportional gain in a speed-control loop.  As you increase gain your current draw will most likely increase, and your motor's response will get snappier up to a point.  Beyond that point, your current draw will increase but all the energy will go into making noise.  So you can save on current draw by decreasing gain -- but at the expense of response coming out of corners.  This same rule applies to KR timers, too, because Keith does the same thing with his timer that a helicopter ESC does internally.

"Timing" refers to the way that a sensorless brushless motor controller works.  Ideally the ESC will control the motor's terminal voltage so that the voltage that's going toward turning the motor is in perfect phase with the switching of the magnetic field across the stator.  Unfortunately, motors possess a characteristic called "leakage inductance" which effectively slows down how rapidly the motor's coils respond to changing voltage.  The "timing" parameter is, as far as I know, a way of compensating for this -- the ESC knows where the motor position is from monitoring the voltage on the terminals, and it uses this knowledge to switch the voltages around a bit earlier than the motor "says" it should.

I don't know what the heck the "PWH" parameter is that you're talking about, so I won't comment on it.
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The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Online Dennis Toth

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Re: ESC setting that affect amp draw?
« Reply #3 on: September 20, 2015, 09:54:58 AM »
"PWM" switching rate parameter, sorry typo. The norm is 8 - 12 what happens at higher rates?

Best,      DennisT

Offline Mark Scarborough

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Re: ESC setting that affect amp draw?
« Reply #4 on: September 20, 2015, 10:15:24 AM »
Dennis, on the Castle link software it describes what each setting does,, google can also help some understanding
I wont begin to try to explain it as my understanding works for me,, but not sure how accurate it is and I dont want to mislead people
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Online Dennis Toth

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Re: ESC setting that affect amp draw?
« Reply #5 on: September 20, 2015, 04:12:22 PM »
Mark,
I have read the description in the Castle Link, they tell generally what it impacts but not how it effects amp draw. One of our big short falls in ECL is still getting the minimum "dead weight" battery being hulled around with no benefit. To that end, I am trying to use the lowest amp draw that gets the job done with the strongest performance.

Tim's information was pretty interesting and the last controllable variable was the PWM switch rate. It seems this may be better if lower but as in most things in ECL the obvious is not always the best approach.

Best,      DennisT

Online Crist Rigotti

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Re: ESC setting that affect amp draw?
« Reply #6 on: September 20, 2015, 05:16:20 PM »
I usually flew with a higher PWM rate because I felt that I had a more "connected" feel to the airplane.  I ahd plenty of overhead on the battery so I never worried about the extra current draw.
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Offline Joe Yau

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Re: ESC setting that affect amp draw?
« Reply #7 on: September 22, 2015, 08:08:01 AM »
I usually flew with a higher PWM rate because I felt that I had a more "connected" feel to the airplane.  I ahd plenty of overhead on the battery so I never worried about the extra current draw.

Would that be 12K or is higher?

Online Crist Rigotti

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Re: ESC setting that affect amp draw?
« Reply #8 on: September 22, 2015, 06:29:18 PM »
Would that be 12K or is higher?

yes, 12K and even 16K if I recall correctly.
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