Motor Torque Derating Using Time-Based Stator Thermal Curves

The patent applies dynamics by implementing a time-varying derating curve that dynamically adjusts the relationship between temperature and torque capacity. Instead of using a static derating algorithm, the system continuously updates the derating factor based on elapsed time at high temperature, allowing the motor to transition from conservative low-temperature derating to more aggressive high-temperature derating as time progresses, thereby enabling sustained high torque output while preventing thermal damage.

The patent changes the parameter of derating factor as a function of time and temperature. The system modifies the derating algorithm to incorporate time-based adjustments, where the derating factor evolves from an initial conservative value to a later relaxed value. This parameter change allows the motor to operate at higher torque levels for extended periods by adapting the thermal management strategy based on cumulative thermal exposure.

The patent applies preliminary action by implementing a time-based derating strategy that starts conservative and progressively relaxes. The system initially applies strong derating to ensure safety when the motor first reaches high temperature, then gradually reduces the derating intensity over time. This preliminary conservative approach transitions into a more productive phase, allowing the motor to utilize fuller torque capacity after demonstrating stable operation at elevated temperatures.

The system dynamically adjusts the derating factor based on the duration of high-temperature operation. The derating curve is not static but evolves over time, starting with aggressive derating to protect against thermal damage and progressively relaxing to allow higher torque output. This dynamic adjustment resolves the contradiction by adapting the safety margin based on cumulative thermal exposure rather than applying a fixed conservative limit.