Systems, methods, and devices for demodulating induction motor instantaneous rotor slot harmonic frequency

摘要

A method and apparatus to dynamically and adaptively demodulate induction motor instantaneous rotor slot harmonic frequency for line-connected squirrel-cage polyphase induction motors. The instantaneous rotor slot harmonic frequency carries essential information on the instantaneous rotor speed. Based on a correlation between the motor's input power and its rotor slot harmonic frequency, a dynamically varying carrier frequency is computed and used in a rotor slot harmonic frequency detector. The rotor slot harmonic frequency detector is based on a superheterodyne principle. It contains a generalized linear-phase low-pass filter, whose bandwidth is estimated dynamically by a filter bandwidth estimator. The rotor slot harmonic frequency detector also includes a latency compensator, which receives the dynamically varying carrier frequency signal and synchronizes it with the output of a frequency demodulator.

主权项

1. A method for demodulating instantaneous rotor slot harmonic frequency for a polyphase induction motor, the method comprising:
receiving measurements indicative of at least one voltage and at least one current associated with the induction motor; converting the voltage measurements to discrete-time voltage samples and the current measurements to discrete-time current samples; determining a complex voltage from the discrete-time voltage samples and a complex current from the discrete-time current samples; receiving motor nameplate data associated with the motor; determining a dynamically varying carrier frequency; determining an estimated filter bandwidth; demodulating the instantaneous rotor slot harmonic frequency based, at least in part, on the dynamically varying carrier frequency, the estimated filter bandwidth, and the motor nameplate data; and storing the demodulated instantaneous rotor slot harmonic frequency; wherein the determining the dynamically varying carrier frequency includes determining an anticipated rotor slot harmonic frequency based, at least in part, upon the complex voltage, the complex current, and the motor nameplate data.