US 6,069,467 A · Sensorless rotor tracking of induction machines with asymmetrical rotor resistance

Abstract

A drive system for providing ac drive power to an induction machine with asymmetrical rotor resistance and for sensorless rotor tracking of the induction machine includes: a signal injector for determining a stator command signal in a reference frame which is aligned with either an estimated rotor reference frame; a signal determiner for determining a feedback stator signal of the induction machine in a stator reference frame; and a rotor position and velocity tracker for using the feedback stator signal to estimate a rotor velocity and position by transforming the feedback stator signal into an orthogonal axis feedback stator signal in the estimated rotor reference frame, isolating a component of the orthogonal axis feedback stator signal which is in-phase with the injected stator command signals, filtering the isolated component to isolate an error term, and generating a position estimate by driving the isolated error term towards zero. In several related embodiments a flux axis stator command signal is injected into the drive system and flux axis and torque axis stator feedback signals are then used for rotor position and velocity tracking.

Claims27

Dependent claims

A drive system for providing ac drive power to an induction machine with asymmetrical rotor resistance and for sensorless rotor tracking of the induction machine, the drive system comprising:

(a) a signal injector for determining a nonrotating ac stator command signal in one or more axes in a reference frame aligned with an estimated rotor position (an estimated rotor reference frame) and transforming the determined stator command signal to a reference frame suitable for injection into the drive system, the drive system being adapted to use the transformed stator command signal to provide an injected stator signal to the induction machine;
(b) a signal determiner for determining a feedback stator signal of the induction machine in a stator reference frame;
(c) a rotor position and velocity tracker (RPVT) for using the feedback stator signal to estimate a rotor position, the RPVT including
an RPVT transformer for transforming the feedback stator signal into a feedback stator signal in the estimated rotor reference frame,
an RPVT in-phase component isolator for extracting a component of the feedback stator signal in the estimated rotor reference frame which is orthogonal to the one or more axes in the estimated rotor reference frame in which the stator command signal is determined, and which is in-phase with the injected stator signal, to isolate an error term, and
a controller for generating a rotor position estimate by driving the isolated error term towards zero.

3 more elements

A drive system for providing ac drive power to an induction machine with asymmetrical rotor resistance and for sensorless rotor tracking of the induction machine, the drive system comprising:

(a) a signal injector for determining and injecting a flux axis stator command signal in a synchronous rotor-flux frame, the drive system being adapted to use the injected stator command signal to provide injected power to the induction machine;
(b) a signal determiner for determining feedback stator signals of the induction machine in a stator reference frame;
(c) a rotor position and velocity tracker (RPVT) for using feedback stator signals to estimate a rotor position, the RPVT including:
a transformer for transforming the feedback stator signals into flux axis and torque axis feedback stator signals in the synchronous rotor flux frame,
a raw error term determiner for determining a raw error term by attenuating non-rotor position dependent components from the flux axis feedback stator signal in the synchronous rotor flux frame and heterodyning the torque axis feedback stator signal in the synchronous rotor flux frame, heterodyning the attenuated flux axis feedback stator signal in the synchronous rotor flux frame, and subtracting the heterodyned torque axis feedback stator signal from the heterodyned attenuated flux axis feedback signal;
an RPVT in-phase signal isolator for extracting a component of the raw error term which is in-phase with the injected stator command signal and isolating an error term, and
a controller for generating a rotor position estimate by driving the isolated error term towards zero.

4 more elements

A drive system for providing ac drive power to an induction machine with asymmetrical rotor resistance and for sensorless rotor tracking of the induction machine, the drive system comprising:

(a) a signal injector for determining a flux axis stator command signal in a synchronous rotor-flux frame, the drive system being adapted to use the determined stator command signal to provide an injected stator signal to the induction machine;
(b) a signal determiner for determining feedback stator signals of the induction machine in a stator reference frame;
(c) a rotor position and velocity tracker (RPVT) for using the feedback stator signals to estimate a rotor position, the RPVT including:
a transformer for transforming the feedback stator signals into flux axis and torque axis feedback stator signals in the synchronous rotor flux frame,
RPVT in-phase signal isolators for extracting components of the flux axis and torque axis feedback stator signals in the synchronous rotor flux frame which are in-phase with the injected stator signal and providing corresponding flux axis and torque axis feedback signal magnitudes;
an isolated error term determiner for determining an isolated error term by attenuating non-rotor position dependent components from the flux axis feedback signal magnitude, heterodyning the torque axis feedback stator signal magnitude, heterodyning the attenuated flux axis feedback stator signal magnitude, and subtracting the heterodyned torque axis feedback stator signal magnitude from the heterodyned attenuated flux axis feedback signal;
a controller for generating a rotor position estimate by driving the isolated error term towards zero.

4 more elements

Dependencies are inferred from the claim text.

Sensorless rotor tracking of induction machines with asymmetrical rotor resistance

Life of this patent

Sensorless rotor tracking of induction machines with asymmetrical rotor resistance

Life of this patent

Abstract

Claims27