Systems and methods for controlling downhole linear motors
First Claim
1. A method for detecting and arresting free fall of a mover in a linear motor for an electric submersible pump (ESP), the method comprising:
- automatically commutating a linear motor of an ESP;
monitoring a speed of a mover in the linear motor wherein during automatic commutation of the linear motor, the speed of the linear motor is not electronically limited;
determining whether the speed of the mover exceeds a threshold speed; and
if the speed of the mover exceeds the threshold speed, disabling automatic commutation of the linear motor and advancing the mover in the linear motor at a predetermined speed.
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Accused Products
Abstract
Systems and methods for detecting and arresting free fall of a mover in a linear motor for an ESP. In one embodiment, the motor of the ESP is initially automatically commutated, but is limited by the back pressure of the fluid being pumped. The drive system of the ESP monitors the speed of the mover in the linear motor and determines whether the speed of the mover exceeds a threshold speed (e.g., by determining whether time differentials between transitions in position sensor signals fall below a threshold value). If the speed of the mover does not exceed the threshold speed, the motor is deemed not to be in free fall. If the speed of the mover exceeds the threshold speed, the motor is considered to be in free fall, so automatic commutation of the motor is disabled and the mover is advanced through its stroke at a predetermined speed.
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Citations
20 Claims
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1. A method for detecting and arresting free fall of a mover in a linear motor for an electric submersible pump (ESP), the method comprising:
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automatically commutating a linear motor of an ESP;
monitoring a speed of a mover in the linear motor wherein during automatic commutation of the linear motor, the speed of the linear motor is not electronically limited;determining whether the speed of the mover exceeds a threshold speed; and if the speed of the mover exceeds the threshold speed, disabling automatic commutation of the linear motor and advancing the mover in the linear motor at a predetermined speed. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An apparatus for detecting and arresting free fall of a mover in a linear motor for an electric submersible pump (ESP), the apparatus comprising:
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an ESP having a linear motor; and an electric drive system coupled to the ESP, wherein the electric drive system includes a controller that is configured to automatically commutate the linear motor, monitor a speed of a mover in the linear motor, determine whether the speed of the mover exceeds a threshold speed, and if the speed of the mover exceeds the threshold speed, disable automatic commutation of the linear motor and advance the mover in the linear motor at a predetermined speed; wherein during automatic commutation of the linear motor, the speed of the linear motor is not electronically limited. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification