| 摘要 |
A microprocessorized thermal protection system and accompanying method measures input voltage and current of an induction motor and derives therefrom continuously updated estimates of the slip dependent rotor resistance during acceleration of the motor. The measurements and calculations of the varying rotor resistance enable determination of the heat generated within the motor based on a thermal model thereof. Phase shift distortions induced by the measurement system are accounted for by determining the value of the stator resistance at start up. In addition, during a brief period following start up, sampling of the voltage/current inputs is suspended to avoid the effects of the initially occurring DC-offset resulting from the application of the voltage input to the inductive motor load.
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