Stall protection?

Info and Discussion about the ESC32 hardware and software

Stall protection?

Postby Nando » Thu Jul 07, 2016 1:40 pm

Hi,

I just got 10 ESC32 V3, to build an X-8.
I love all the features, and look forward to using Can in the future, and the feedback. And I’m happy to have a esc with mounting holes.

I flew with BLheli esc’s and after swapping them with these it still flew stable even before extra tuning, Esc's stayed cold.
But I had some vibration problems, causing a prop to hit the ground during landing. It was on concrete and would be able spin a moment later but it was not spinning, and very quickly after that the flight computer gave the command to stop, but the smoke was already coming out of the ESC. (A fet burned.)

Is there a protection build in to prevent this?
On BLheli they have “Stall protection” and “low RPM power protection” I’m not sure why they are less prone to this type of failing (at least for me), but if it’s one of these features, maybe they can be implemented.

If it’s very likely to burn a ESC every time you tip over on landing, it would be reason to switch back to ESC’s that don’t have that problem for me.
If you say It’s unlikely then I’ll throw a towel on a slowly spinning prop to see what happens.
Or if I should try it with different settings, I would like to do that.

My setup:
T-motor 4014-11
16" APC - MR
6S 20.000
No heatsink on ESC32
1X the supplied 330uf 35v capacitor

ESC settings:
ACTIVE_FREEWHEEL 1
ADVANCE 15
AUDIO_VOLUME 0
BAD_DETECTS_DISARM 32
BAUD_RATE 230400
DIRECTION 1
ESC_ID 1
FF1TERM 1.89563e-07
FF2TERM 0.0027018
GOOD_DETECTS_START 48
ITERM 0.005
MAX_CURRENT 20
MAX_PERIOD 12000
MIN_PERIOD 50
MOTOR_POLES 24
PTERM 0.5
PWM_HI_VALUE 2000
PWM_LO_VALUE 1010
PWM_MAX_PERIOD 25000
PWM_MAX_VALUE 2250
PWM_MIN_PERIOD 2000
PWM_MIN_START 1010
PWM_MIN_VALUE 950
PWM_RPM_SCALE 5800
RPM_MEAS_LP 0.75
SERVO_D 0
SERVO_DUTY 5
SERVO_MAX_RATE 1000
SERVO_P 0.05
SERVO_SCALE 360
STARTUP_MODE 1
START_CURRENT 0.75
START_VOLTAGE 0.75
SWITCH_FREQ 20
THR1TERM 0
THR2TERM 1
Nando
 
Posts: 2
Joined: Wed Jul 06, 2016 11:14 am

Re: Stall protection?

Postby JussiH » Thu Jul 07, 2016 8:01 pm

It should be unlikely - under normal conditions the ESC should detect a stall, reduce power and stop. Both the current limiter and the bad detects function should have kicked in.

I would advise to change the cap to a larger 50V for 6S, but it is likely to not have anything to do with this issue, but for a 6S setup, I would recommend using a 50V cap.

Also, pay attention to the current limiter settings. Use the telemetry to work out the max current at full speed and set limit a few amps higher. If you have the current limiter set way higher than needed, it might not work as intended and help you prevent a problem like this. 20A at 6S is a good 450-500 watts of power and its probably over the top for that motor and prop to begin with.

But the ESC should have detected the motor stopping and shut off power. If it didnt, I would suspect that there probably was another issue with that particular ESC.
JussiH
 
Posts: 2103
Joined: Thu Jun 21, 2012 9:25 pm

Re: Stall protection?

Postby Nando » Fri Jul 08, 2016 12:39 pm

I've not measured any current greater than 19,3A (peak), full throttle is 16,5A and the maximum current is set at 20.
I was thinking about increasing this, not lowering. The wiki states 10% extra.
In flight it should never reach this, it hovers at 40% without payload.

I'll look at swapping the cap.
Nando
 
Posts: 2
Joined: Wed Jul 06, 2016 11:14 am


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