Apparatus and method of rotational alignment of permanent magnet tandem motors for electrical submersible pump

1. An electrical submersible well pump assembly, comprising:

first and second motors, each having a housing, the first and second motors having first and second shafts, respectively, each of the first and second motors having a plurality of rotor sections, a rotor keyway between each of the rotor sections and the shaft of each of the motors, each of the rotor sections having a plurality of circumferentially spaced permanent magnets, defining magnetic poles;

the second shaft having a splined end with external splines;

a coupling connected with the first shaft for rotation in unison, the coupling having internal splines that engage the external splines for causing the first and second shafts to rotate in unison;

a housing connector that connects the housing of the first motor with the housing of the second motor, the housing connector having a bore with the coupling located therein; and

alignment means for rotationally aligning the magnetic poles of the first shaft with the magnetic poles of the second shaft prior to securing the housings of the first and second motors together, the alignment means comprising a coupling keyway in the coupling that is at a controlled orientation relative to the rotor keyway of the first shaft, a second shaft splined end keyway between the external splines is at a controlled orientation relative to the rotor keyway of the second shaft, and a coupling key within the coupling keyway and the second shaft splined end keyway.

2. The assembly according to claim 1 , wherein the coupling key prevents full meshing engagement of the first and second shafts with the internal splines unless the keyways of the first and second shaft and the coupling are aligned with each other.

3. An electrical submersible well pump assembly, comprising:

first and second motors, each having a housing, the first and second motors having first and second shafts, respectively, each of the first and second motors having a plurality of rotor sections, each of the rotor sections having a plurality of circumferentially spaced permanent magnets, defining magnetic poles;

the first and second shafts each having a splined end with external splines;

a coupling having internal splines that engage the external splines of the first and second shafts for causing the first and second shafts to rotate in unison;

a housing connector that connects the housing of the first motor with the housing of the second motor, the housing having a bore with the coupling located therein;

a first shaft alignment device on the splined end of the first shaft that is in a controlled orientation relative to the magnetic poles of the rotor sections of the first shaft, the first shaft alignment device comprising an alignment indicia on the first shaft;

a second shaft alignment device on the splined end of the second shaft that is in a controlled orientation relative to the magnetic poles of the rotor sections of the second shaft, the second shaft alignment device comprising an alignment indicia on the second shaft;

a coupling indicia on an exterior of the coupling, enabling an operator to manually rotate one of the shafts relative to the other to align alignment indicia on the first shaft with alignment indicia on the second shaft before engaging the first and second shafts to each other with the coupling.

4. An electrical submersible well pump assembly, comprising:

first and second motors, each having a housing, the first and second motors having first and second shafts, respectively, each of the first and second motors having a plurality of rotor sections, a rotor keyway between each of the rotor sections and the shaft of each of the motors, each of the rotor sections having a plurality of circumferentially spaced permanent magnets, defining magnetic poles;

the second shaft having a splined end with external splines;

a coupling connected with the first shaft for rotation in unison, the coupling having internal splines that engage the external splines for causing the first and second shafts to rotate in unison;

a housing connector that connects the housing of the first motor with the housing of the second motor, the housing connector having a bore with the coupling located therein; and

alignment means for rotationally aligning the magnetic poles of the first shaft with the magnetic poles of the second shaft prior to securing the housings of the first and second motors together, the alignment means comprising,

a protuberance on an exterior of the second shaft adjacent the splined end of the second shaft, the protuberance being at a controlled orientation relative to the rotor keyway of the second shaft,

an orientation slot on an second end of the coupling, the orientation slot having two edges facing each other and curving from a circumferentially wider dimension at an entrance to a guide slot portion, the guide slot portion being at a controlled orientation relative to the rotor keyway of the first shaft, and

wherein moving the splined shaft of the second shaft towards the first motor causes the protuberance to enter the orientation slot, which rotates the second shaft until the protuberance enters the guide slot portion.

5. The assembly according to claim 4 , wherein the two edges are parallel within the guide slot portion.

6. The assembly according to claim 4 , wherein the guide slot portion comprises a first guide slot portion, the alignment means comprising a second guide slot portion that is disposed 180 degrees from the first guide slot portion.

7. The assembly according to claim 4 , wherein the internal splines in the coupling are located axially between the guide slot portion and the first shaft, so that the external splines engage the internal splines only after the protuberance enters the guide slot portion.