Method and system for self-calibration of an induction machine drive

Claim 2

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.

Claim 3

The self-calibration method as set forth in claim 1 , wherein the Q factor and the D factor are expressed, respectively, as: Q_Factor = ∫ t = 0 t f  W   ( t )   v qs rf    t D_Factor = ∫ t = 0 t f  W   ( t )   v ds rf    t where W is the windowing factor, rf is the reference frame, qs is the q-axis, ds is the d-axis, t f is the total amount of time for data collection and v qs rf and v ds rf are the stator voltages in the estimated rotor flux synchronous reference frame.

Claim 4

The method as set forth in claim 1 , wherein the induction machine acts as a motor as torque is distributed through the torque flow path from the input member to the output member and as a generator as torque is distributed through the torque flow path from the output member to the input member; the Q factor and the D factor relationship to slip gain estimates uniformly changing as slip gain estimates increase during both motoring operation and generating operation as torque command changes.

Claim 5

The method set forth in claim 2 , wherein the induction machine acts as a motor as torque is distributed through the torque flow path from the input member to the output member and as a generator as torque is distributed through the torque flow path from the output member to the input member; the Q factor and the D factor relationship to slip gain estimates uniformly changing as slip gain estimates increase during both motoring operation and generating operation as torque command changes.

Claim 6

The self-calibration method set forth in claim 1 wherein the torque command waveform comprises a pattern of uniform steps of commanded torque between zero and non-zero values.

Claim 7

The self-calibration method of claim 1 wherein the torque command waveform comprises a pattern of uniform steps of commanded torque between two non-zero values.

Claim 8

The self-calibration method of claim 1 wherein the torque commanded waveform comprises a pattern of progressively changing steps of commanded torque defining a progressively changing trajectory.

Claim 9

A self-calibrating control system for controlling torque in a torque transfer drive having a torque input member and a torque output member, the system including a programmable digital processor having a memory in which control algorithms are stored and a central processor unit for executing control processing steps in accordance with control algorithm instructions, the steps comprising: commanding a change in torque on the torque input member; determining commanded q-axis and d-axis stator voltage; calculating the product of the collected stator voltage and a desired windowing factor, the windowing factor 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; correcting the slip gain estimate based on the Q and D factors for a given change in commanded torque relative to a slip gain estimate that is correctly tuned; 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.

Claim 10

A self-calibrating control system for controlling torque in a torque transfer drive having a torque input member and a torque output member, the system including a programmable digital processor having a memory in which control algorithms are stored and a central processor unit for executing control processing steps in accordance with control algorithm instructions, the steps comprising: commanding a change in torque on the torque input member; determining commanded q-axis and d-axis stator voltage; calculating the product of the collected stator voltage and a desired windowing factor, the windowing factor 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; correcting the slip gain estimate based on the Q and D factors for a given change in commanded torque relative to a slip gain estimate that is correctly tuned; 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.

Claim 11

The self-calibrating control system as set forth in claim 8 , wherein the Q factor and the D factor are expressed, respectively, as: Q_Factor = ∫ t = 0 t f  W   ( t )   v qs rf    t D_Factor = ∫ t = 0 t f  W   ( t )   v ds rf    t where W is the windowing factor, rf is the reference frame, qs is the q-axis, ds is the d-axis, and t f is the total amount of time for data collection and v qs rf and v ds rf are the stator voltages in the estimated rotor flux synchronous reference frame.

Claim 12

The system of claim 8 wherein the torque command waveform comprises a pattern of uniform steps of commanded torque between zero and non-zero values.

Claim 13

The system of claim 8 wherein the torque command waveform comprises a pattern of uniform steps of commanded torque between two non-zero values.

Claim 14

The system of claim 8 wherein the torque commanded waveform comprises a pattern of progressively changing steps of commanded torque defining a progressively changing trajectory.