Homopolar permanent-magnet-biased action magnetic bearing with an integrated rotational speed sensor

摘要

Radial poles are placed around a radial actuator target mounted on a body. The poles are separated from a cylindrical surface of the target by radial gaps and adapted to communicate a magnetic flux with it. The radial poles are equipped with electrical control windings and magnetically coupled to form magnetic control circuits. A flux return pole is adjacent to the body, separated from it by an air gap and adapted to communicate a magnetic flux with the radial actuator target. A permanent magnet generates a magnetic bias flux in the magnetic bias circuit formed by the radial actuator target, the radial poles and the magnetic flux return pole. A radial force is exerted on the actuator when the control windings are energized with a current. A Hall effect sensor measures bias magnetic field in the air gap between the magnetic flux return pole and the body. A feature on a body is adapted to produce a circumferentially local discontinuity in the magnetic field measured by the Hall effect sensor as the body rotates.

主权项

1. An electromagnetic actuator with an integrated rotational speed sensor for radial support of a rotor having a rotational axis, the electromagnetic actuator comprising:
a first and a second radial control poles adjacent to an outer surface of the rotor, separated from the outer surface of the rotor by first and second radial control air gaps, respectively, and configured to communicate magnetic flux with the outer surface of the rotor, the first radial control pole and the second radial control pole magnetically coupled to each other, and the first radial control pole, the second radial control pole and the rotor forming a radial control magnetic circuit; a first and a second electrical windings wound around the first and the second radial control poles respectively and producing radial control magnetic flux in the radial control magnetic circuit when energized with electrical currents; a bias magnetic flux return pole spaced axially from the radial control poles, adjacent to the outer surface of the rotor, separated from the outer surface of the rotor by an air gap and configured to communicate magnetic flux with the outer surface of the rotor, and the rotor, the first radial control pole, the second radial control pole and the bias magnetic flux return pole forming a magnetic bias circuit; a permanent magnet magnetically coupled to the first radial control pole, the second radial control pole and the bias magnetic flux return pole and configured to generate magnetic bias flux in the magnetic bias circuit; the radial control magnetic flux and the magnetic bias flux exert a radial force on the rotor when superimposed in the first and the second radial control air gaps; a Hall effect sensor configured to measure a magnetic field in the air gap between the magnetic flux return pole and the rotor; and a speed sensor triggering notch on the outer surface of the rotor that produces a circumferentially local discontinuity in the magnetic field measured by the Hall effect sensor.