FEDEVEL
Platform forum

SkyDvv , 02-02-2024, 05:13 AM

Heey, Hope you're Okay
I was working on an ESC before with SILABs Controller...
There was first prototype that worked perfectly fine, Even better than the industrial expensive ones.
But we wanted to make a second version to improve the programing or confugrating experience.
So, We made another one by only:
1- adding 1 led as a power indicator
2- made it smaller
3- Resistor and diode arrays to save space
4- making the programming more easier by adding some pin headers

I programmed 2 of them and got to test them, they act wierd at high speed, the just get triggered then stop, trigger, stop for 3 of 4 times then run normal..
I was wondering if any of this helps to figure out the problem, I'm still an engineering student, i don't know much about motors or machines.
PS: I suspected the feedback routning, may it cause a problem if one of the phases is a little bit longer than the others?

I will attach some of videos I captaured, notice that backward max speed is 1112, forward os 1912 and stop is 1512.
At low speed it works perfectly fine.

QDrives , 02-02-2024, 04:53 PM

Sensorless I assume?
Are all 3 phases working correctly?
Swapping motor and board with the correct working (first) one?

SkyDvv , 02-05-2024, 12:00 AM

Hello, thanks for waiting that much..
Well yes it's sensor-less, and the three phases are working fine I'll attach a photo of my Oscilloscope for 2 phases(It's only daul channel 😭 but the third one works the same as them)
I swapped the motors and tested with 2 different boards, they works on Bluerobotics ESC smoothly, I have set the same settings on BLheli like them, Like i did for the first version and they work fine
I want to tell you that those ESCs are already integrated to ROV we are making, the whole 8 ESCs for the thruster are made by us, so no, the old ones work fine, the problem is with the newer one, and I don't really know why.

SkyDvv , 02-05-2024, 12:00 AM

SkyDvv , 02-05-2024, 12:01 AM

a friend of mine told me that this readings are not good?
is that right? :"

QDrives , 02-05-2024, 09:11 PM

"a friend of mine told me that this readings are not good?" --are you referring to the scope picture?
It is a six step commutation PWM plot. However, I would expect some back EMF too in the 'idle' periods.
Are you constantly driving the low side FETs during that period?

SkyDvv , 02-05-2024, 11:54 PM

Yeah I meant the scope readings
and about the the back EMF I guess the controller sense for feedback, I really don't know the code is written in assembly and that's really hard for me to trace :"
here's the link for the codes and configuration(I used J configuration)
and about feedback the go to controller direct with voltage divider as seen in the attached photo.

QDrives , 02-06-2024, 08:52 PM

This is probably how it is driven: https://www.researchgate.net/profile/William-Nothwang/publication/253772458/figure/fig5/AS:668690718658563@1536439699254/A-typical-commutation-scheme-for-BLDC-motors-with-high-side-PWM-where-A-represents-the.jpg
This is a bit how I would expect it: https://www.researchgate.net/profile/Adrian-Ioan-Lita/publication/320621981/figure/fig4/AS:553660263874560@1509014301752/BEMF-ON-ALL-3-PHASES_Q640.jpg except that for low, it is NOT PWM'ing.
Looking at the scope picture, the second ramp up of green looks acceptable. (First) ramp up of yellow and ramp down down not so much. This could also be due to correction due to the feedback.
Use a glitch trigger to capture a longer off period and see how the signals are prior to that event.

SkyDvv , 02-07-2024, 09:00 AM

Oh I see, I'll check if that disturbed phase is the long routed one or no if it is, i'll try to do a surgery on it and try to test again..
I really appreciate your help, It helped em alot
and I will keep you updated