An apparatus is disclosed that increases an efficiency of the submersible brushless motor with annular magnetic segments on the rotor (increase in efficiency) (by minimizing static losses during the passage of the magnetic flux through the stator magnetic circuit) while increasing its meant time between failures (MTBF) by ensuring efficient operation of a cooling circulation circuit electric motor (by simultaneously providing the maximum possible cross-section and the maximum surface for heat transfer in a flow longitudinal circulation channel formed between the surfaces of the magnetic circuit and the rotor).

An electrical submersible well pump assembly has first and second permanent magnet motors. The first motor drive shaft is connected to a coupling that has internal splines for receiving an externally splined end of the second motor drive shaft. Alignment devices rotationally align magnetic poles of the first drive shaft with the magnetic poles of the second drive shaft prior to securing the housings of the first and second motors together. The alignment devices may be a coupling irregularity in the internal splines that is at a controlled orientation relative to the magnetic poles of the first shaft and a shaft irregularity in the external splines that prevents the second drive shaft from fully engaging the coupling unless the shaft irregularity is in a specified rotational position relative to the coupling irregularity.

An electrical submersible well pump assembly has first and second permanent magnet motors. The first motor drive shaft is connected to a coupling that has internal splines for receiving an externally splined end of the second motor drive shaft. Alignment devices rotationally align magnetic poles of the first drive shaft with the magnetic poles of the second drive shaft prior to securing the housings of the first and second motors together. The alignment devices may be a coupling irregularity in the internal splines that is at a controlled orientation relative to the magnetic poles of the first shaft and a shaft irregularity in the external splines that prevents the second drive shaft from fully engaging the coupling unless the shaft irregularity is in a specified rotational position relative to the coupling irregularity.

An electric submersible pumping system includes a motor filled with motor lubricant, a pump driven by the motor, and a fluid expansion chamber connected to the motor. The fluid expansion chamber includes a seal bag filled with a seal bag lubricant and a bellows contained within the seal bag. The bellows includes an interior in fluid communication with the motor and an exterior in fluid communication with the seal bag lubricant.

An electric submersible pumping system includes a motor filled with motor lubricant, a pump driven by the motor, and a fluid expansion chamber connected to the motor. The fluid expansion chamber includes a seal bag filled with a seal bag lubricant and a bellows contained within the seal bag. The bellows includes an interior in fluid communication with the motor and an exterior in fluid communication with the seal bag lubricant.

A system and method for enhanced magnet wire insulation is described. The system of the invention provides an enhanced insulation for magnet wire that is capable of withstanding high temperatures and provides a seal against water that is needed in electric submersible pump (ESP) applications. The enhanced insulation of the system of the invention provides the dielectric advantages of polyimide tape, such as Kapton tape, while also including the advantages of organic polymer thermoplastic insulation that prevents the delaminating at high temperatures that may occur in pumping applications using a variety of electrical submersible motors.

A method and system for monitoring operation of a motor may include initially determining a no load torque versus temperature characteristic of the motor over a range of operating temperatures. After a period of operation, a no load torque value and temperature of the motor may be determined. Motor temperature may be measured by a local thermistor or the like. Motor torque may be determined from measured motor current. The motor torque and temperature may then be compared to the initial torque versus temperature characteristic to determine a change in load of said motor due to break down of motor oil, worn bearings, or similar condition. In some embodiment, the method and system may be used with a downhole tool for drilling a well, such as a rotary steerable system.

An electric submersible pumping system for use in pumping fluids from a wellbore includes a motor, a pump driven by the motor, and a fluid expansion module connected to the motor. The fluid expansion module includes a piston seal housing and a piston assembly contained within the piston seal housing. The piston assembly includes a piston body having an exterior surface, a plurality of seals connected to the exterior surface of the piston body and a pressure equalization system. The pressure equalization system reduces a pressure differential between fluid in an annular space between the plurality of seals and fluid surrounding the first piston assembly.

A linear actuator for pumping comprising a stator having an inner opening, a shaft having a plurality of permanent magnets spaced linearly in the axial direction, the shaft disposed in the stator opening and configured to reciprocate linearly in the axial direction relative to the stator, the stator comprising a first stator assembly having a plurality of pole sections spaced linearly in the axial direction and a plurality of coils disposed therebetween, a second stator assembly having a plurality of pole sections spaced linearly in the axial direction and a plurality of coils disposed therebetween, a bearing assembly positioned axially between the first stator assembly and the second stator assembly, and the bearing assembly having a width that is a function of the spacing of the plurality of pole sections of the first stator assembly and the second assembly and the spacing of the plurality of permanent magnets of the shaft.

A linear actuator for pumping comprising a stator having an inner opening, a shaft having a plurality of permanent magnets spaced linearly in the axial direction, the shaft disposed in the stator opening and configured to reciprocate linearly in the axial direction relative to the stator, the stator comprising a first stator assembly having a plurality of pole sections spaced linearly in the axial direction and a plurality of coils disposed therebetween, a second stator assembly having a plurality of pole sections spaced linearly in the axial direction and a plurality of coils disposed therebetween, a bearing assembly positioned axially between the first stator assembly and the second stator assembly, and the bearing assembly having a width that is a function of the spacing of the plurality of pole sections of the first stator assembly and the second assembly and the spacing of the plurality of permanent magnets of the shaft.