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.

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 tool includes a device including a housing and a rotor, the rotor to rotate about a longitudinal axis, and an axial gap generator including a stator assembly positioned adjacent to the rotor. The axial gap generator generates a voltage signal as a function of a gap spacing between the stator assembly and the rotor, the gap spacing being parallel to the longitudinal axis.

A load control apparatus for controlling a power supply to an electrical load connected to an output terminal includes an overcurrent protection circuit having a power switch through which the electrical load receives a load current and a sensor component in series with the power switch that is configured to generate a voltage drop corresponding to the current rise speed of a load current from an input terminal to the output terminal. The protection circuit includes a driver circuit configured to detect an overcurrent depending on the voltage drop generated by the sensor component and/or at the power switch, and to switch off the power switch upon detection of an overcurrent within a switch-off period. The overcurrent protection circuit can include a power supply control circuit having a sensor component adapted to measure a supply voltage notified to a control unit of the load control apparatus adapted to control power supplied to the load.

A downhole-type system includes a rotatable shaft, a downhole-type magnetic bearing coupled to the rotatable shaft, a downhole-type sensor, a surface-type controller, and a surface-type amplifier coupled to the magnetic bearing. The magnetic bearing can control levitation of the rotatable shaft. The downhole-type sensor can detect a position of the rotatable shaft in a downhole location and generate a first signal based on the detected position. The surface-type controller can receive the first signal, determine an amount of force to apply to the shaft, and generate a second signal corresponding to the determined amount of force. The surface-type amplifier can receive the second signal, amplify the second signal to a sufficient level to drive the magnetic bearing to apply force to the rotatable shaft to control the levitation of the rotatable shaft at the downhole location, and transmit the amplified second signal to the magnetic bearing.

A solid state switch has at least one FET-type device and at least one thyristor-type device coupled in parallel to the at least one FET-type device. The at least one FET-type device is constructed with a first power loss profile based on a rated current of an electrical device; and the at least one thyristor-type device is constructed with a second power loss profile based on a surge current associated with the electrical device.

A tool includes a device including a housing and a rotor, the rotor to rotate about a longitudinal axis, and an axial gap generator including a stator assembly positioned adjacent to the rotor. The axial gap generator generates a voltage signal as a function of a gap spacing between the stator assembly and the rotor, the gap spacing being parallel to the longitudinal axis.

Current sensors measure current flowing into and out of an inductive load such as a solenoid coil and provide signals to a processor when the difference between the two measured currents exceeds a threshold. A solenoid coil and electronic devices driving it are protected from damage caused by a short circuit at the connections to the coil.

A fluid module includes a fluid rotor configured to rotatably drive or be driven by fluid produced from a wellbore. A first shaft is coupled to the fluid rotor. The first shaft is configured to rotate in unison with the fluid rotor. A thrust bearing module includes a thrust bearing rotor. A second shaft is coupled to the thrust bearing rotor. The second shaft is configured to rotate in unison with the thrust bearing rotor. The second shaft is coupled to the first shaft. An electric machine module includes an electric machine rotor. A third shaft is coupled to the electric machine rotor. A third shaft is configured to rotate in unison with the electric machine rotor. The third shaft is coupled to the second shaft. The third shaft is rotodynamically isolated from the first shaft and the second shaft.

A device includes a rotor to rotate about a longitudinal axis, a magnetic bearing actuator, and an axial gap generator including a stator assembly adjacent to the rotor, the axial gap generator to generate an amount of power as a function of a gap spacing between the stator assembly and the rotor, the gap spacing parallel to the longitudinal axis, and the axial gap generator to supply the amount of power to a control coil of the magnetic bearing actuator.