Abstract: Systems and methods for constructing electric motors including both permanent magnet elements and inductive elements. In one embodiment, a motor is implemented of an ESP system has multiple rotor sections that are mounted end-to-end within the bore of the stator. The permanent magnet elements and inductive elements may be combined within individual rotor sections, or they may be segregated so that one rotor section has only one type or the other. The inductive elements of the rotor allow the motor to be started without a VFD, and without knowing the position of the rotor within the motor. The permanent magnet elements synchronize the rotor with the rotating stator fields when the rotor approaches the operating frequency of the drive.

Abstract: A submersible electric motor has feature to enhance thermal conductivity from the motor interior to the exterior. The motor has a cylindrical housing and a stator rigidly mounted within housing. A rotatable rotor is located within the stator. A gap formed between the stator's outer diameter and the inner wall of the housing is filled with a high thermal conductivity material to improve heat transfer from the motor. The remaining portion of the housing may be filled with a dielectric lubricant that has lesser thermal conductivity than the high thermal conductivity material.

Abstract: Systems and methods for constructing electric motors in which a stator core includes inner and outer portions that enable slots for magnet windings to be open during construction and closed in the completed motor. One embodiment comprises a method in which an inner stator core having a plurality of slots is formed by stacking a set of laminations. The slots are open radially outward from an axis of the inner stator core and which are configured to accommodate turns of magnet wire. After the magnet wire is positioned in the open slots, an outer stator core comprising stacked laminations is positioned around the inner stator core, enclosing the slots. The inner and outer stator cores are then positioned within a housing and assembled into a downhole motor.

Abstract: A submersible electric motor has feature to enhance thermal conductivity from the motor interior to the exterior. The motor has a cylindrical housing and a stator rigidly mounted within housing. A rotatable rotor is located within the stator. A gap formed between the stator's outer diameter and the inner wall of the housing is filled with a high thermal conductivity material to improve heat transfer from the motor. The remaining portion of the housing may be filled with a dielectric lubricant that has lesser thermal conductivity than the high thermal conductivity material.

Abstract: An apparatus and method for controlling a motor/blower system to provide a constant fluid flow by iteratively loading revised stator frequency values and stator voltage values to a variable frequency drive. Target DC bus current values corresponding to constant fluid flow rates are predetermined and stored as a function of the desired fluid flow rate, the operating frequency, and system specific constants or calculated by the controller as a function thereof during system operation. Actual DC bus current is measured with a current sensor and compared with the target DC bus current. Operating frequency is estimated using a PI controller based on the difference between measured and target DC bus current values. Operating voltage values corresponding to operating frequencies and system specific constants are predetermined and stored in memory or calculated by the controller during system operation. An updated target DC bus current, operating frequency and operating voltage are determined upon each iteration.

Abstract: An apparatus and method for controlling a motor/blower system to provide a constant fluid flow by iteratively loading revised stator frequency values and stator voltage values to a variable frequency drive. Target DC bus current values corresponding to constant fluid flow rates are predetermined and stored as a function of the desired fluid flow rate, the operating frequency, and system specific constants or calculated by the controller as a function thereof during system operation. Actual DC bus current is measured with a current sensor and compared with the target DC bus current. Operating frequency is estimated using a PI controller based on the difference between measured and target DC bus current values. Operating voltage values corresponding to operating frequencies and system specific constants are predetermined and stored in memory or calculated by the controller during system operation. An updated target DC bus current, operating frequency and operating voltage are determined upon each iteration.