Permanent magnet motor

A method of assembling a downhole permanent magnet motor (PMM), comprising:

• aligning a plurality of rotor laminations, wherein each rotor lamination defines a plurality of apertures, wherein each of the plurality of apertures comprises a first aperture configured to receive a first permanent magnet element, a second aperture configured to receive a second permanent magnet element, and a central opening having a keyway notch configured to receive a driveshaft key, so that the keyway notches of each rotor lamination is aligned with the keyway notches of the other rotor laminations;
• inserting a first permanent magnet element into the first apertures of the rotor laminations;
• inserting a second permanent magnet element into the second apertures of the rotor laminations;
• inserting a drive shaft into the central openings of each of the rotor laminations;
• inserting a driveshaft key into the keyway notch of each of the rotor laminations, thereby securing a rotor assembly to the drive shaft, wherein the rotor assembly comprises the rotor laminations, the first permanent magnet element, and the second permanent magnet element;
• and
• inserting the drive shaft and the rotor assembly into a longitudinal opening of a stator.

A method of retrofitting a different type of rotor into an electric submersible pump (ESP) electric motor, comprising:

• removing a head from the ESP electric motor;
• removing a first rotor from a stator of an ESP electric motor, wherein the first rotor is a first rotor type selected from a group consisting of a conventional rotor type, a permanent magnet motor (PMM) rotor type, and a hybrid PMM rotor type;
• installing a second rotor into the stator of the ESP electric motor, wherein the second rotor is a second rotor type selected from the group consisting of the conventional rotor type, the PMM rotor type, and the hybrid PMM rotor type, wherein the second rotor type is different from the first rotor type;
• and
• installing the head onto the ESP electric motor.