Sealless downhole system with magnetically supported rotor

A method comprising:

• radially magnetically levitating a first rotor within a first stator;
• radially magnetically levitating a second rotor within a second stator;
• radially magnetically levitating a third rotor within a third stator;
• rotodynamically isolating the first rotor from the second rotor by a first rotodynamic isolator coupling;
• and
• rotodynamically isolating the second rotor from the third rotor by a second rotodynamic isolator;
• rotating the first shaft below a critical speed of the first rotor;
• rotating the second shaft below a critical speed of the second rotor;
• and
• rotating the third shaft below a critical speed of the third rotor.

A wellbore production system comprising:

• a fluid module comprising:
• a fluid rotor configured to rotatably drive or be driven by fluid produced from a wellbore;
• a first shaft coupled to the fluid rotor, the first shaft configured to rotate in unison with the fluid rotor;
• a fluid stator that surrounds the fluid rotor;
• a first magnetic radial bearing configured to support a first end of the first shaft to the fluid stator;
• and
• a second radial magnetic bearing configured to support a second end of the first shaft to the fluid stator;
• a thrust bearing module comprising:
• a thrust bearing rotor;
• a second shaft coupled to the thrust bearing rotor, the second shaft configured to rotate in unison with the thrust bearing rotor, the second shaft coupled to the first shaft, the second shaft configured to transfer torque between the first shaft and the second shaft, the second shaft being rotodynamically isolated from the first shaft;
• and
• a thrust bearing stator that surrounds the thrust bearing rotor;
• and
• an electric machine module comprising:
• an electric machine rotor;
• a third shaft coupled to the electric machine rotor, the third shaft configured to rotate in unison with the electric machine rotor, the third shaft coupled to the second shaft or the first shaft, the third shaft configured to transfer torque between the second shaft and the third shaft or the first shaft, the third shaft being rotodynamically isolated from the first shaft and the second shaft;
• an electric stator that surrounds the electric machine rotor;
• a third magnetic radial bearing configured to support a first end of the second shaft to the electric stator;
• and
• a fourth radial magnetic bearing configured to support a second end of the second shaft to the electric stator;
• wherein the system is configured to rotate the first shaft below a critical speed of the first shaft, rotate the second shaft below a critical speed of the second shaft, and rotate the third shaft below a critical speed of the third shaft.