Motor angular position control

Patent metadata

Field	Value
Publication number	US-12119775-B2
Application number	US-202418430178-A
Country	US
Kind code	B2
Filing date	Feb 1, 2024
Priority date	Mar 3, 2020
Publication date	Oct 15, 2024
Grant date	Oct 15, 2024

Abstract

A motor controller to control rotational speed of an output shaft of an electric motor. The motor controller includes a proportional controller and a time-optimal controller. The proportional controller controls the rotational speed when a present rotational position of the shaft is between a target rotational position and a switching point, inclusively. The time-optimal controller controls the rotational speed when the present rotational position is not between the target rotational position and the switching point. Also introduced herein are aspects pertaining to determining the switching point in a manner that minimizes overshooting the target rotational position while maximizing expediency at which the target rotational position is reached.

First claim

What is claimed is:

1. A method comprising:
determining a switching point to be used by a motor controller that is operable to control rotational speed of an output shaft of an electric motor, wherein:
the motor controller comprises a proportional controller and a time-optimal controller;
the proportional controller controls the rotational speed when a present rotational position of the shaft is between a target rotational position and the switching point, inclusively;
the time-optimal controller controls the rotational speed when the present rotational position is not between the target rotational position and the switching point;
wherein the switching point is determined via operation of a processor and a memory storing code executable by the processor, and
wherein the operation of the processor determines the switching point by:
determining which one of N curves corresponds to a predetermined system communications delay, wherein Nis a positive integer, and wherein each of the N curves relates a counter delay factor β to candidate switching points; and
selecting the switching point based on a smallest one of the candidate switching points that results in a value of the counter delay factor being less than one for the determined one of the N curves.

2. The method of claim 1 , wherein selecting the switching point comprises:
determining the smallest one of the candidate switching points that results in a value of the counter delay factor being less than one; and
selecting the switching point as a rotational position that is larger than the determined smallest one of the candidate switching points.

3. The method of claim 2 , wherein the selected switching point is a result of rounding up the determined smallest one of the candidate switching points to a multiple of a rotational positioning precision of the shaft.

4. The method of claim 2 , wherein the selected switching point is greater than the determined smallest one of the candidate switching points by an amount that includes a margin to account for unknown factors.

Assignees

• Schlumberger Technology Corp

Inventors

• Wu Jian
• Madhireddy Ramakrishna
• Wicks Nathaniel

Classifications

• E21B7/068

  drilled by a down-hole drilling motor (down-hole drives per se E21B4/00, E21B7/067 takes precedence) · CPC title

• E21B3/022

  Top drives · CPC title

• F02D25/02

  to synchronise speed · CPC title

• E21B44/00

  Automatic control systems specially adapted for drilling operations, i.e. self-operating systems which function to carry out or modify a drilling operation without intervention of a human operator, e.g. computer-controlled drilling systems; Systems specially adapted for monitoring a plurality of drilling variables or conditions · CPC title

• H02P6/15

  Controlling commutation time · CPC title