Both Talon’s and Spark maxes have the ability to current limit by reducing the maximum current available to a motor. What actually is happening within the hardware/software that is allowing this to happen?
I am not an electrical engineer but:
I assume the controller is measuring the current, and if it exceeds a threshold, it reduces the output voltage (by switching the MOSFETs on for less time pwm-style) until the current falls below the threshold.
and the image below it
Electrically, most motor controllers use big transistors configured to work like switches connecting or disconnecting the motor from the battery. By doing this very rapidly and for regular intervals (IE, 80% on, 20% off), the motor will effectively get some fraction of the battery voltage. For a given shaft speed, applied voltage corresponds to current flow through the motor.
So, software-wise, all a motor controller has to do to limit current is reduce that fraction of time that the transistors are in the ON state.
Vasista’s link is a great specific example of how software decides to do that limit, and to what extent.
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