Overspeed protection for sensorless electric drives
AssigneeHoneywell International Inc.
InventorsEvgeni Ganev, Edward L. Johnson, Cuong V. Nguyen
Life of this patent
Estimating the term…
Abstract
Overspeed protection of sensorless electric drives is needed in the aerospace industry. Methods for overspeed protection may include software implementations, hardware implementations or combinations thereof. Typical high-speed rotating machinery is designed to sustain overspeed operation of up to 50% beyond maximum normal operation. This requirement leads to substantial penalties in weight and volume. The methods of the present invention may allow for an opportunity to reduce this overspeed design to about 5 to 15%, typically about 7%.
Claims20
A method for protecting an electric drive from an overspeed condition, the method comprising:
- limiting an external speed command for the electric drive to 100% speed;
- dropping a current command in response to a rise in a speed feedback due to a decrease in motor load;
- limiting a maximum frequency applied to a stator of the electric drive;
- and
- measuring a frequency and an amplitude of phase currents from the electric drive.
A system for protecting an electric drive from an overspeed condition comprising:
- a signal conditioning circuit to convert an analog motor current feedback signal to a logic level signal representing a speed of the electric drive;
- an oscillator to generate a real-time clock reference;
- and
- programmable logic device to compare a motor frequency signal with a predetermined overspeed frequency limit.
A computer readable media for protecting an electric drive from an overspeed condition comprising:
- a code segment for limiting an external speed command for the electric drive to 100% speed;
- a code segment for dropping a current command in response to a rise in a speed feedback due to a decrease in motor load;
- a code segment for limiting a maximum frequency applied to a stator of the electric drive;
- a code segment for measuring a frequency of three phase currents from the electric drive;
- and
- a code segment for checking the speed feedback against a speed feedback limit.
Dependencies are inferred from the claim text.