Rotating machines and rotors therefor are disclosed. The bearings may be magnetic bearings configured to magnetically levitate the rotor. The rotors may include a hollow fiber-reinforced composite shaft and a magnetic bearing rotor core disposed on the shaft and configured for use with the magnetic bearing. In some examples, the rotating machines may be electrical machines.

A downhole-type system includes a rotatable rotor, a magnetic thrust bearing coupled to the rotor, and a mechanical thrust bearing coupled to the rotor. The magnetic thrust bearing is configured to support a first portion of an axial load of the rotor during rotor rotation, and the mechanical thrust bearing is configured to support a second portion of the axial load of the rotor during rotor rotation.

A stator for an electric motor may have a substantially annular shape centered around a central axis and may include a stator core having a plurality of teeth consecutively arranged in a circumferential direction, and a plurality of coils wound around respective teeth of the plurality of teeth. The plurality of coils may be grouped into a plurality of phase groups. The stator may include in association with the respective phase groups: at least one loop wire connecting at least two coils of the respective phase group in series with each other with the at least one loop wire being positioned at a radially inner portion of the stator, and at least two end wires respectively connected to two end coils of the respective phase group. The at least two end wires may be configured to be connected to a power source to energize the coils of the respective phase group.

A fluid rotor is configured to move or be rotated by a working fluid. A fluid stator surrounds the fluid rotor. The fluid stator is spaced from the fluid rotor and defines a first annular fluid gap in-between that is in fluid communication with an outside environment exterior the downhole-type pump. A radial magnetic bearing includes a first portion coupled to the fluid rotor and a second portion coupled to the fluid stator. The first portion is spaced from the second portion defining a second annular fluid gap in-between that is in fluid communication with the outside environment exterior the downhole-type pump.

An electronic magnetic bearing fault-tolerant drive module includes a first plurality of switching elements and a second plurality of switching elements. At least one winding is interposed between the first plurality of switching elements and the second plurality of switching elements. The first and second switching elements are configured to selectively operate in a first mode and a second mode to generate an electromagnetic field. The electronic magnetic bearing fault-tolerant drive module is configured to detect one or more electrical faults including an open-circuit fault of at least one of the first and second switching elements.

A system to provide power to a downhole-type tool includes a downhole-type electric motor that can be positioned in a wellbore and a variable speed drive electrically connected to the electric motor, in which the downhole-type electric motor can operate at rotary speeds of at least 6,000 rotations per minute (rpm), the variable speed drive can control and supply power to the electric motor when the electric motor is positioned at a downhole location inside the wellbore, and the variable speed drive can be at a surface of the wellbore.

A flywheel system includes a rotor and a fixture. The rotor forms an aperture. The fixture includes a bottom support, a top support, and a shaft connecting the bottom support to the top support. The shaft passes through the aperture. The bottom support and the top support are outside opposite ends of the aperture. The rotor is configured to rotate about the shaft. A method for operating a flywheel system includes converting between rotational energy of a rotor and electrical energy in windings of a generator stator that is implemented in a stationary shaft passing through an aperture of the rotor, while the rotor is rotating about the shaft.

A position sensor includes a plurality of E-shaped ferromagnetic cores arranged to define a circular opening therethrough to receive a shaft. Each E-shaped ferromagnetic core has a plurality of teeth, wherein adjacent E-shaped ferromagnetic cores of the arranged plurality of E-shaped ferromagnetic cores have an overlapping tooth. The position sensor further includes a frame surrounding the arranged plurality of E-shaped ferromagnetic cores, with the E-shaped ferromagnetic cores coupled to the frame.

A vapor compression system and method for operating the vapor compression system are provided. The vapor compression system includes a compressor, a condenser, and at least one check valve disposed between the compressor and the condenser. The method provides for the transmitting of a shutdown command to the compressor, the compressor including a rotating shaft and a magnetic bearing, the magnetic bearing having an active mode and an inactive mode, the magnetic bearing levitating the rotating shaft in the active mode. The method further provides for the maintaining of the magnetic bearing in the active mode during a minimum time period, the magnetic bearing switching from the active mode to the inactive mode after the minimum time period is reached.

Disclosed are a magnetic bearing, a compressor and an air conditioner. The magnetic bearing includes a radial stator, wherein the radial stator has a plurality of stator teeth extending inwardly in a radial direction thereof; two axial stators are arranged on two axial sides of the stator teeth, respectively; and radial control coils are wound on the stator teeth, each radial control coil being located outside an area of the stator teeth covered oppositely by the two axial stators. The magnetic bearing, the compressor and the air conditioner can effectively reduce the degree of coupling between a radial electromagnetic control magnetic circuit and an axial electromagnetic control magnetic circuit, and reduce the control difficulty of the magnetic bearing.