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US 2009/0058345 A1Published application
Motor controller providing position feedback correction
AssigneeRockwell Automation Technologies, Inc.
InventorsMark R. Cooper, Thomas D. Lundell
Life of this patent
Estimating the term…
Abstract
A motor controller employs absolute encoder signals to periodically assess the existence of cumulative error in a position signal derived from an incremental encoder signal. In one embodiment the absolute encoder signals are extracted from commutation switches of the motor eliminating the need for a separate absolute encoder.
Claims20
A motor controller system for the control of an electric motor comprising:
- a first input for receiving an incremental encoder signal from an incremental encoder driven by the electric motor;
- a second input for receiving an absolute encoder signal from an absolute encoder driven by the electric motor;
- a feedback circuit receiving a command signal for the control of a position of the electric motor and for receiving a position feedback signal indicating a position of the electric motor and derived from the incremental encoder signal, the feedback circuit producing an error signal used to drive and the electric motor;
- and
- a correction circuit receiving the incremental encoder signal and the absolute encoder signal to compare the two to derive a feedback error signal on a regular basis for a detection of errors in the position feedback signal derived from the incremental encoder signal.
2 more elements
A method of controlling an electric motor comprising the steps of:
- (a) receiving an incremental encoder signal from an incremental encoder driven by the electric motor;
- (b) receiving an absolute encoder signal from an absolute encoder driven by the electric motor;
- (c) receiving a command signal for the control of a position of the electric motor and a position feedback signal indicating a position of the electric motor and derived from the incremental encoder signal, the feedback circuit producing an error signal used to drive and the electric motor;
- and
- (d) receiving the incremental encoder signal and the absolute encoder signal to compare the two to derive a feedback error signal on a regular basis for a detection of errors in the position feedback signal derived from the incremental encoder signal.
2 more elements
Dependencies are inferred from the claim text.