Patent ID: 6566840
Filing Date: 2003-05-20
Classification: H02P

Abstract:
A self-calibration method for estimating slip gain of an induction machine system with a rotor and a fixed stator that form a torque flow path from a torque input member to a torque output member, the method comprising:commanding a change in torque on the torque input member; determining commanded q-axis and d-axis stator voltages; calculating the product of the stator voltage and a desired windowing function, the windowing function being a multiplier for stator voltage following a change in torque command to effect a correctly tuned slip gain estimate; calculating Q and D factors for a current transient event as a time integral of a windowed q and d axis stator voltage waveform; determining, using Q and D factors, whether an estimate of slip gain is accurate; and correcting the slip gain estimate for a given change in commanded torque based on the Q and D factors relative to a slip gain estimate for a correctly tuned system; and repeatedly varying the commanded torque between predetermined values with a predetermined frequency, thereby creating a torque command waveform that causes the slip gain estimate to converge to an accurate value.