Stall Detection?

14 years 9 months ago #26512994 by mattb
Stall Detection? was created by mattb
After reading various posts and warnings about motor current vs battery current, I have some concerns about using this controller in my application.

I will be using the controller to control a motor which has a stall current of almost 900 amps (r=.041ohms.) However, since this is a continous duty application, I do not want the motor to ever draw more then 90amps. My understanding is that with the way your controller measures current, it will be very hard to limit the motor current in the event of a mechanical failure which stalls the motor. Besides for the damge the device could mechanically do to itself, it also seems that this type of stall could potentially damage the controller. Is this correct?

Since I will be using the controller in closed loop speed control, is there any type of stall detection shutdown/fault?



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14 years 9 months ago #26528155 by cosma
Replied by cosma on topic Re:Stall Detection?
Your analysis is correct. The controller can protect against stalls but only up to a point.

Stall detection verifies that the current at low pwm does not exceed a certain limit. The number is roughly 1A for each PWM output level (e.g. 10A at power level of 10). Translated in motor amps this can still be a lot of current.

The controller will also stop if it doesnt detect any movement for a a few seconds while power level is above ~50%. Practically, this will only work if the motor is totally blocked as any movement of the encoder would be understood by the controller as the motor is actually moving.

Best would be to back up the above protections with a fuse place in series with the motor.

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