2014 - best ESC at the moment?

[econfly]

i'm pretty sure you want med or low for high pole count.....

That's what I get for thinking instead of testing... You are probably right. In my mind, faster switching would make sense at a given RPM if the pole count is high -- less time between poles, and therefore shorter pulses would make timing easier (more granular, easier to hit the sweet spot). By this logic, low pole count should be fine with slow or fast switching while high pole count my require faster switching. But that's the problem with thinking it through without testing. I'm really just guessing.

 

[sk8brd]

i read higher pole count higher timing but theres not a lot of info. just gonna have to bench test. waiting for barman to get back to me, he was running kde 4012's on hobbywings w/out sync issues on his a2 wood frame build.

here is flight tests's take http://flitetest.com/articles/quadcopter-build-esc-programming-turnigy-plush

 

[Motopreserve]

That's what I get for thinking instead of testing... You are probably right. In my mind, faster switching would make sense at a given RPM if the pole count is high -- less time between poles, and therefore shorter pulses would make timing easier (more granular, easier to hit the sweet spot). By this logic, low pole count should be fine with slow or fast switching while high pole count my require faster switching. But that's the problem with thinking it through without testing. I'm really just guessing.

Econ: you're just the man for the job! As if we haven't tasked you with enough testing already

the thing that originally brought clarity now confuses me... The analogy to setting the points timing on an older motorcycle. I understand the concept of perfecting the timing to fire when the piston will maximize force from the combustion. But I'm not sure how that would be effected by changing the size of the piston. Or more accurately, if there were more pistons following right behind the first one in the same cylinder. You'd have to have the firing happening more often - but how would that effect how advanced the timing would happen?

I don't understand why there wouldn't be a formula based on the number of poles and the size of the poles. Shouldn't there be some math to line up the firing given those attributes (if they were known)???

 

[sk8brd]

found this on hell freak. (Kv x volts x poles count / 20). if you want to check out the info.....http://www.helifreak.com/showthread.php?t=249106

 

[econfly]

Econ: you're just the man for the job! As if we haven't tasked you with enough testing already

the thing that originally brought clarity now confuses me... The analogy to setting the points timing on an older motorcycle. I understand the concept of perfecting the timing to fire when the piston will maximize force from the combustion. But I'm not sure how that would be effected by changing the size of the piston. Or more accurately, if there were more pistons following right behind the first one in the same cylinder....

I don't understand why there wouldn't be a formula based on the number of poles and the size of the poles. Shouldn't there be some math to line up the firing given those attributes (if they were known)???

I'll probably have to do it when I get to my next build -- and I've been looking at KDE motors for that project. The problem is the black box of timing. That has to be very responsive, and much faster than the switching frequency. Without knowing the details of how an ESC does the job, it's pretty difficult to know how best to adjust things.

 

[Motopreserve]

Without knowing the details of how an ESC does the job, it's pretty difficult to know how best to adjust things.

...and those that know aren't talking!

 

[Motopreserve]

found this on hell freak. (Kv x volts x poles count / 20). if you want to check out the info.....http://www.helifreak.com/showthread.php?t=249106

I posted that on another thread asking for confirmation that it was correct. Never got an answer. RTRyder once told me that a basic setup might start at the freq closest to the pole count (so if they were 14 pole, 12k, if they were 20 pole 18k etc). But he also said you have to mess around and experiment with what works for particular motor/ESC combo.

 

[sk8brd]

motopreserve do you mind telling me where your getting the figures for 12k, 18k from just want to see what low is.

 

[gtranquilla]

Unfortunately these little and simple 3 phase motors and ESCs do not incorporate a feedback system from the motor so as to correct such situations automatically. The bigger industrial systems do have that feature.

I thought the opposite. It's near impossible to get any solid data on this. This might be another question for Chris and the boys at KDE. They were gracious with their explanation and definition of the high pole count/pancake motors.

The dance of "to SimonK or not, Maytek or not, BLHeli or not, HobbyWing not working with SuperX or is it?...." makes my head hurt.

I finally bit the billet and bought a set of KDE motors and ESCs for a new build. Pricey - but if for some reason they don't work together - I know exactly who to call.

HERE is the best (and only) explanation I've really ever found.

 

[Motopreserve]

motopreserve do you mind telling me where your getting the figures for 12k, 18k from just want to see what low is.

Sorry should have clarified. The hobbywing platinum pro 30A has a program adjustment of several advance timings. 2 of them are 12 & 18. They seem highly adjustable. I just couldn't get them to work with my superx. So I moved on sooner than I would have liked. Maybe I'll go back to try them more extensively since that build will now have another FC that had no issue with them.

THIS manual shows the timing options.

 

[Motopreserve]

Unfortunately these little and simple 3 phase motors and ESCs do not incorporate a feedback system from the motor so as to correct such situations automatically. The bigger industrial systems do have that feature.

I thought that's what the 3rd phase was doing - feeding back data when it's not firing. But that's based on the explanation in the link from above post. With this ESC stuff the plot thickens, and then thickens some more the more I research and try to understand...

 

[gtranquilla]

Indirect feedback, if there is any would not be very reliable.
The larger industrial brushless motors one feedback mechanism is the brushless motors have a black/white BCD on the motor shaft and a photoelectric sensor (5 wires between motor and esc).
From that sensor the speed controller can determine both the motor rpm and the rotation direction.

I thought that's what the 3rd phase was doing - feeding back data when it's not firing. But that's based on the explanation in the link from above post. With this ESC stuff the plot thickens, and then thickens some more the more I research and try to understand...

 

[kloner]

these motors were using are some weird stuff. as a guy that uses common sense as an engineering mindset, they confuse the hell out of me

http://en.wikipedia.org/wiki/Brushless_DC_electric_motor

it's a form of ac that's more controlled that comes from a dc current

 

[econfly]

these motors were using are some weird stuff. as a guy that uses common sense as an engineering mindset, they confuse the hell out of me

http://en.wikipedia.org/wiki/Brushless_DC_electric_motor

it's a form of ac that's more controlled that comes from a dc current

I reviewed an ESC recently and went into lots of detail on control signal, output pulsing, waveform appearance, etc., including videos of oscilloscope output. It's a little dense, but there is a fair amount of detail on the output 3-phase approximate AC waveform and switching.

http://www.multirotorforums.com/showthread.php?19923-Product-Review-**-JETI-HiCopter-30A-Opto-ESC

 

[gtranquilla]

A bit more info on "cogging" etc.
see report number 4 by "the other dave".
http://www.rcgroups.com/forums/showthread.php?t=28021

 

[adarsh_007]

Hi Pro Guys,

Need some info on programing the escs. I have two setups.
setup-1
Tmotor 4014-9 (400kv) motor with hobbywing 40A opto esc. What should the timing setting in the esc be? Low, Mid or High?
Setup-2
Tomotor U7 (420kv) motor with Tiger T80A esc. same question, what should the timing be set to?

Thanks in anticipation guys.

Regards,
Adarsh

 

[kloner]

on the u7, leave it alone as it comes, all you do is set the throttle endpoints and fly em

not sure on th 4014, but just put one prop on and run it, rap the throttle, make it do a prolonged run and check for heat, listen for sounds, look for the motor getting jammed up....

 

[gtranquilla]

these motors were using are some weird stuff. as a guy that uses common sense as an engineering mindset, they confuse the hell out of me

http://en.wikipedia.org/wiki/Brushless_DC_electric_motor

it's a form of ac that's more controlled that comes from a dc current

That is an excellent lead with respect to the issue of "detent" or what we previously referred to as cogging. This portion in particular:
Controller implementations:
Because the controller must direct the rotor rotation, the controller requires some means of determining the rotor's orientation/position (relative to the stator coils.) Some designs use Hall effect sensors or a rotary encoder to directly measure the rotor's position. Others measure the back EMF in the undriven coils to infer the rotor position, eliminating the need for separate Hall effect sensors, and therefore are often called sensorless controllers.

A typical controller contains 3 bi-directional outputs (i.e. frequency controlled three phase output), which are controlled by a logic circuit. Simple controllers employ comparators to determine when the output phase should be advanced, while more advanced controllers employ a microcontroller to manage acceleration, control speed and fine-tune efficiency.

Controllers that sense rotor position based on back-EMF have extra challenges in initiating motion because no back-EMF is produced when the rotor is stationary. This is usually accomplished by beginning rotation from an arbitrary phase, and then skipping to the correct phase if it is found to be wrong. This can cause the motor to run briefly backwards, adding even more complexity to the startup sequence. Other sensorless controllers are capable of measuring winding saturation caused by the position of the magnets to infer the rotor position.


I suspect that the "detent" or cogging during running is a situation where the synchronization between motor and ESC is off to the point where there are repeated momentary attempts to run the motor backwards while it is still rotating forward, i.e., braking..

 

[Quadcopterfly]

Maytech and ZTW ESCs are different

ZTW recently started selling ESCs under their own brand here in the USA. If you have previously used Maytech V1 or HK Blue series, you've already used ZTW ESCs, both vendors relable the base ZTW hardware and firmware with their own branding. If you compare the manual that comes with a Maytech vs. the one that comes with the HK Blue they're the same document with only the branding and seller ID being different. The quality of the ZTW manufacturing is definitely a notch above a lot of the other Chinese manufacturers and being an all nFET design they're solid reliable hardware. I use the HK Blue variant on a lot of the stuff I currently have flying mainly because they're dirt cheap and ship from the US warehouse.

As far as refresh rates go, 490 is about the max that PWM can handle if you look at how it works and do the math. Certain I2C ESCs can go higher but for all practical purposes even 490 is pushing it on some of the less well made standard ESCs as the timing circuitry isn't all that solid. So it's nice to know the firmware is written to be capable of 600hz refresh, unfortunately current hardware will never get there as long as it's being driven with a PWM input.

Ken

Ken,
I am afraid your info fall behind. Maytech ESCs hardware is different from ZTWs, though firmware almost same. Hardware is in great difference, especially from 40A.

 

[RTRyder]

Ken,
I am afraid your info fall behind. Maytech ESCs hardware is different from ZTWs, though firmware almost same. Hardware is in great difference, especially from 40A.

That is true now but the older V1 versions are ZTW hardware and software. I've had Maytech V1 30 A, HK Blue, and a ZTW all side by side and unwrapped on the bench, there is no difference at all in the hardware of the older versions. Also all three use the same programming card which they could not do if there any real difference in the hardware and software...

Ken