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EP-4586465-B1 - ROTOR AND ASSOCIATED ELECTRIC MACHINE, MOTOR COMPRESSOR AND MAGNETIC COUPLING

EP4586465B1EP 4586465 B1EP4586465 B1EP 4586465B1EP-4586465-B1

Inventors

  • DURANTAY, LIONEL
  • ANBARASU, RAMASAMY
  • HUMBERT, PIERRE
  • LEBOEUF, NICOLAS
  • CURE, Alexander

Dates

Publication Date
20260513
Application Date
20240110

Claims (14)

  1. Rotor (5) comprising: - a cylindrical stack (7) of laminations (8) including: o at least a first group (15) of slots and a second group (16) of slots arranged to form a first pole (P1), the first group of slots being arranged to form a magnetic flux along a direct axis (P) of the pole resulting from the first and second group of slots, at least some of the first group of slots comprising first permanent magnets (12), the second group of slots being arranged from either side of the slots of the first group to provide a separation for the magnetic flux from adjacent poles and lying along a quadrature axis (Q) of said pole, at least some slots of the second group of slots comprising first permanent magnets, and o at least a second pole (P2), the first pole (P1) and the second pole (P2) forming a pair of poles of the rotor (5), - magnetic flux barriers (22) arranged at each end of each slot of the first and second groups of slots, characterized in that the rotor further comprises: - two half shafts (6) enclosing the stack of laminations and forming a shaft of the rotor, the rotor being a non-through shaft rotor, - two non-magnetic and electrically insulating end disks (9), each non-magnetic and electrically insulating end disk being interposed between one end of the stack and a half shaft, and - a first set of tie rods (100) connecting the two half shafts to keep the laminations of the stack compacted between the two half-shafts, each tie rod of the first set of tie rods being arranged between two adjacent slots of the first or second groups of slots.
  2. Rotor according to claim 1, wherein at least some slots of the second group (16) of slots closest to the periphery of the stack (7) of laminations (8) comprises non-magnetic and electrically insulating blocks (23).
  3. Rotor according to claim 1 or 2, wherein each half shaft (6) comprises a flange (10) in contact with a non-magnetic and electrically insulating end disk (9), the rotor further comprising a non-magnetic retaining ring (13) enclosing the stack (7) of laminations (8) and partially the flanges of the half shafts, the diameter of the laminations being smaller than the diameter of the flanges so that the inner surface of the retaining ring is in contact with the peripheral surface of the flanges, the retaining ring being made of a non-magnetic and electrically insulating material.
  4. Rotor according to claim 3, wherein the retaining ring (13) is made of a stainless-steel.
  5. Rotor according to claim 3, wherein the retaining ring (13) is made of composite fibers.
  6. Rotor according to any one of claims 3 to 5, wherein the laminations (8) of the stack (7) are separated by at least one intermediate non-magnetic and electrically insulating disk (14) in two sub-stacks of laminations, the diameter of the intermediate non-magnetic and electrically insulating disk being equal to the diameter of the flanges (10) so that the retaining ring is in contact the peripheral surface of the intermediate non-magnetic and electrically insulating disk.
  7. Rotor according to any one of claims 1 to 6, wherein the cylindrical stack (7) is divided in a longitudinal direction of the stack by a plane (PL1) including a rotation axis (A) of the rotor in two similar half cylinders (C1, C2), the first pole (P1) being arranged in a first half cylinder (C1), the second pole (P2) being arranged in the second half cylinder (C2) and similar to the first pole, the first and second groups (15, 16) of slots of the first pole (P1) and the first and second groups (15a, 16a) of slots of the second pole (P2) being symmetrical with respect to the plane (PL1), tie rods of the first groups of tie rods (100) being arranged between the first and the second poles .
  8. Rotor according to any one of claims 1 to 6, further comprising a third pole (P3) and a fourth pole (P3) similar to the first pole (P1), the second pole (P2) being similar to the first pole (P1), wherein the cylindrical stack (7) is divided in a longitudinal direction of the stack in four similar cylindrical portions (C10, C11, C12, C13), the first pole (P1) being arranged in a first cylindrical portion (C10), the second pole (P2) being arranged in a second cylindrical portion (C11), the third pole (P3) being arranged in a third cylindrical portion (C12), the fourth pole (P4) being arranged in the fourth cylindrical portion (C13), so that the first and second groups (15, 16) of slots of the first pole (P1) and the first and second groups (15a, 16a) of slots of the second pole (P2) are symmetrical with respect to a first plane (PL10) including a rotation axis (A) of the rotor, and the first and second groups (15b, 15c, 16b, 16c) of slots of the third and fourth poles (P3, P4) and the first and second groups of slots of the first and second poles are symmetrical with respect to a second symmetrical plane (PL20) including the rotation axis (A) of the rotor and perpendicular to the first plane.
  9. Rotor according to claim 8, further comprising a third group of slots (25) extending along the rotation axis (A) of the rotor (5) and lodging a rod (26) made of a non-magnetic and electrically insulating material.
  10. Rotor according to claim 8 or 9, further comprising a fourth group of slots (27a, 27b, 27c, 27d), each slot of the fourth group of slots extending between the rotation axis (A) of the rotor and the peripheral surface of the stack (7) and being oriented according to the first or second plane (PL10, PL20), each slot of the fourth group of slots comprising third permanent magnets (28) and magnetic flux barriers (29) arranged at the end of each slot of the fourth group of slots near the peripheral surface of the stack.
  11. Rotor according to claim 10, further comprising a second set of tie rods (30), arranged between the rotation axis of the rotor and the first, second, third and fourth poles, and between the slots of the fourth group of slots (27a, 27b, 27c, 27d).
  12. Electric machine (3) comprising a stator (4) and rotor (5) according to any one of claims 1 to 11, the rotor being inserted in the stator.
  13. Motor Compressor (1) comprising an electric machine (3) according to claim 12 and a compression section (2), the rotor being connected to the compression section.
  14. Magnetic coupling (40) comprising a rotor (5) according to any one of claim 1 to 11, and an external rotor (41), the rotor being inserted in the external rotor.

Description

The present invention concerns permanent magnets rotors, a magnetic coupling and an electric machine comprising such rotors, and a motor compressor comprising such an electric machine. It is known that the power density of an electric machine depends on the magnetic flux generated by the rotor and the stator of the electric machine. For a permanent magnet rotor, the magnetic flux generated by the rotor is proportional to the volume of magnets of the rotor. It is also known that the power density of an electric machine increases linearly by increasing linearly the rotation speed of the rotor. It is known to arrange permanent magnets in a rotor comprising a central hole so that each permanent magnet extends between the central hole and the periphery of the rotor. The permanent magnets are arranged regularly in the rotor to concentrate the magnetic flux (flux concentration rotor type). Document CN 110 556 944 B discloses a permanent magnet rotor comprising a shaft. The document US 2009/0224624 discloses a permanent magnet rotor comprising a shaft enclosing a magnetic mass comprising multilayers of permanent magnets (multi layers rotor type). The magnetic mass comprises stacked rotor laminations including a first group of slots and a second group of slots arranged to form a pole, and a center hole lodging the rotor shaft. The first group of slots is arranged to form a magnetic flux along a direct axis of the pole resulting from the first and second group of slots. The second group of slots is arranged to provide a separation for the magnetic flux from adjacent poles and lying along a quadrature axis of said pole Some of the first and second group of slots are arranged to receive permanent magnets, maximising the quadrature inductance versus the direct inductance leading to create reluctance torque on top of interaction torque produced by magnets and currents injected in a stator encompassing the rotor to maximize the torque generated by the rotor . In the rotors known form the prior art, as the shaft goes through the magnetic mass to lodge the shaft, the volume of magnets arranged in the magnetic mass is limited. Further, the rotation speed of the rotor is limited to reduce the centrifuge forces acting on the rotor laminations in order to limit the constraints on the periphery of the center hole of the rotor laminations. The constraints on the center holes may shear the rotor laminations. The rotation speed of the rotor may be chosen so that the peripheral speed of the rotor does not exceed 200 m.s-1. It is therefore proposed to overcome wholly or partially these disadvantages. In view of the foregoing the invention proposes a rotor comprising: a cylindrical stack of laminations including: o at least a first group of slots and a second group of slots arranged to form a first pole, the first group of slots being arranged to form a magnetic flux along a direct axis of the pole resulting from the first and second group of slots, at least some of the first group of slots comprising first permanent magnets, the second group of slots being arranged from either side of the slots of the first group to provide a separation for the magnetic flux from adjacent poles and lying along a quadrature axis of said pole, at least some slots of the second group of slots comprising first permanent magnets, ando at least a second pole, the first pole and the second pole forming a pair of poles of the rotor. The rotor further comprises: magnetic flux barriers arranged at each end of each slot of the first and second groups of slots,two half shafts enclosing the stack of laminations and forming a shaft of the rotor, the rotor being a non-through shaft rotor,two non-magnetic and electrically insulating end disks, each non-magnetic and electrically insulating end disk being interposed between one end of the stack and a half shaft, anda first set of tie rods connecting the two half shafts to keep the laminations of the stack compacted between the two half-shafts, each tie rod of the first set of tie rods being arranged between two adjacent slots of the first or second groups of slots. Advantageously, at least some slots of the second group of slots closest to the periphery of the stack of laminations comprise non-magnetic and electrically insulating blocks. Preferably, each half shaft comprises a flange in contact with a non-magnetic and electrically insulating end disk, the rotor further comprising a non-magnetic retaining ring enclosing the stack of laminations and partially the flanges of the half shafts, the diameter of the laminations being smaller than the diameter of the flanges so that the inner surface of the retaining ring is in contact with the peripheral surface of the flanges, the retaining ring being made of a non-magnetic and electrically insulating material. Advantageously, the retaining ring is made of a stainless-steel. Preferably, the retaining ring is made of composite fibers. Advantageously, the laminations of the st