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I've got an outrunner brushless DC motor (Flipsky 63100 190KV 5500W if that's relevant). It'll be used to spin normally sometimes, but I also need it at other times to give resistance to motion.

Basically, I'll be running a current through it to spin one direction, but the motor will be forced to spin the opposite direction due to other forces. Would this hurt the motor in any way? Would it degrade the magnets or coils inside?

I read on here that this is what a torque motor is for, but this is what I have and I don't want to break the motor.

I understand that ESCs have a "governor mode" which monitors the RPM and gives more power to try and maintain the expected speed, but I've turned it off. If I resist the rotation of the motor, it slows down and I don't feel it drawing more power to overcome the resistance.

I don't have any way to measure the voltage/amp being drawn to actually know if any extra current is being drawn, but I don't have any reason to suspect the motor is getting any extra power when encountering resistance.

Any advice?

I figured I'd get a multimeter and check the current to see if there's more current drawn when the motor is stalled or not. But from what I've read elsewhere, if there's no extra current draw then the motor and ESC can be used in this way?

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  • \$\begingroup\$ Coil insulation deterioration and demagnetization are promoted by high temperature. How hot does it get? \$\endgroup\$
    – Abel
    Jun 19, 2022 at 0:45
  • \$\begingroup\$ @Abel I just purchased a meter that I can stick between the battery and ESC to see if there is a current spike. I guess I should buy an infrared thermometer too to make sure it doesn't get too hot. \$\endgroup\$
    – zapshe
    Jun 19, 2022 at 1:06
  • \$\begingroup\$ No need. Hot to touch is a pretty good indicator. If you can hold it for a prolonged amount of time, chances are, it is less than 125 F \$\endgroup\$
    – Abel
    Jun 19, 2022 at 1:19
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    \$\begingroup\$ Measuring the delta in the coil resistance (and applying a formula) is a way to tell what the actual average coil temperature is. Better than measuring surface temperature, not as good as having an actual sensor buried within the coil. \$\endgroup\$ Jun 19, 2022 at 4:02
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    \$\begingroup\$ People do this all the time. What is happening is that you are running the motor as a generator (regeneration mode). The controller has to support it. But other than that it is not problematic.\ \$\endgroup\$
    – user57037
    Jun 19, 2022 at 4:08

1 Answer 1

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There are two types of BLDC motor, each requiring its own type of ESC. Self commutated, and Hall-sensor commutated.

A self commutated motor uses the back-EMF generated by the motor for the ESC to figure out where it is, and drive the coils correctly. The ESC is normally designed to spin the motor at a speed, and may get confused if the motor is forced backwards. As far as it's concerned, the load is too large.

A sensored motor uses the Hall-sensed position of the rotor to work out how to drive the coils. This is the type used in Segways and hoverboards. The ESC can be designed to operate in all four quadrants of the speed/torque curve.

Generally, as long as a BLDC motor is neither overheated nor overspeeded, it and the ESC won't be damaged or degraded. The ESC however might get confused and stop trying to drive the motor until reset.

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  • \$\begingroup\$ I see, that makes sense. The motor does have a hall wire and sensors, but the ESC doesn't take it. If the motor being impeded confuses the ESC I'll have to find a better one or a better solution for my situation. Thanks a lot!! \$\endgroup\$
    – zapshe
    Jun 19, 2022 at 4:30

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