Amazon.com, Inc.
Model-based current limiter for an electric motor

Abstract:

A current limiter for protecting a motor from overheating. An algorithm is disclosed for dynamically limiting the motor current, such as motors used in robotics. The algorithm uses a thermal model of the motor, which provides a real-time estimate of a coil temperature using instantaneous power consumption of the motor and a thermocouple measurement from the motor's printed circuit board. There are multiple potential outputs from the current limiter algorithm, such as the maximum power that can be consumed without overheating the coils, and an estimate of how long the motor could deliver a specified high torque before overheating.