Inductrack magnet configuration

• US 6,633,217 B2
• Filed: 06/26/2002
• Issued: 10/14/2003
• Est. Priority Date: 06/29/2001
• Status: Expired due to Term

• Current Assignee: Lawrence Livermore National Security LLC (Government of the United States of America)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Post, Richard Freeman
• Primary Examiner(s): Barrera, Ramon M.
• Application Number:
  US10/185,439
• Publication Number:
  US 20030005849A1
• Time in Patent Office: 475 Days
• Field of Search: 310/12, 335/306, 104/281-286
• US Class Current: 335/306
• CPC Class Codes: B60L 13/04 Magnetic suspension or levitation for vehicles
• CPC Class Codes: B60L 2200/26 Rail vehicles
• CPC Class Codes: H01F 7/0236 Magnetic suspension or levitation for vehicles B60L13/04; magnetic bearings F16C39/063

Abstract

A magnet configuration comprising a pair of Halbach arrays magnetically and structurally connected together are positioned with respect to each other so that a first component of their fields substantially cancels at a first plane between them, and a second component of their fields substantially adds at this first plane. A track of windings is located between the pair of Halbach arrays and a propulsion mechanism is provided for moving the pair of Halbach arrays along the track. When the pair of Halbach arrays move along the track and the track is not located at the first plane, a current is induced in the windings and a restoring force is exerted on the pair of Halbach arrays.

Claims

1. A magnet configuration, comprising;

a first Halbach array having a first magnetic field and a second Halbach array having a second magnetic field, wherein said first Halbach array and said second Halbach array are magnetically and structurally connected together to form a first pair of Halbach arrays, wherein said first Halbach array comprises magnet configurations positioned with respect said second Halbach array and said second Halbach array comprises magnet configurations positioned with respect said first Halbach array such that a first component of said first magnetic field and a first component of said second magnetic field substantially cancel at a first plane between said first Halbach array and said second Halbach array, and a second component of said first magnetic field and a second component of said second magnetic field substantially add at said first plane;

a track of windings between said first pair of Halbach arrays;

a propulsion mechanism for moving said first pair of Halbach arrays along said track, wherein when said first pair of Halbach arrays move along said track and said track is not located at said first plane, a current is induced in said windings and a restoring force is exerted on said first pair of Halbach arrays; and

means for adjusting said restoring force.

2. The magnet configuration of claim 1, wherein said means for adjusting said restoring force is selected from the group consisting of (i) means for displacing said first Halbach array with respect to said second Halbach array, and (ii) means for displacing said second Halbach array with respect to said first Halbach array.

3. The magnet configuration of claim 1, wherein said means for adjusting said restoring force is selected from a group consisting of (i) at least one adjusting screw operatively positioned to mechanically displace said first Halbach array with respect to said second Halbach array, and (ii) at least one adjusting screw operatively positioned to mechanically displace said second Halbach array with respect to said first Halbach array.

4. The magnet configuration of claim 1, further comprising a vehicle attached to said first pair of Halbach arrays, further comprising a sensor attached to said vehicle, wherein said means for adjusting said restoring force further comprises a servo-control system that continuously adjusts said restoring force in response to a command from said sensor.

5. The magnet configuration of claim 4, wherein said sensor is selected from the group consisting of a pitch sensor, a yaw sensor and a load sensor.

6. The magnet configuration of claim 1, wherein said track further comprises a column of electrically connected coils that intercept no net flux when they are centered with respect to the Halbach arrays on either side but when there is a sidewise displacement, flux will be coupled, inducing currents in said coils, which interact with the Halbach array nearest said coil, and thereby providing a sideways centering force resulting from the Halbach array pushing away from said coil wherein said first pair of Halbach arrays is configured as the armature of a linear synchronous motor;

and

a channel configuration iron rail having two lower pole faces operatively positioned above said first pair of Halbach arrays, wherein edge fields of said first pair of Halbach arrays are attracted to said two lower pole faces of said iron rail.

7. The magnet configuration of claim 6, further comprising an interleaved array of one or more conductors, symmetrically located with respect to the midplane of the said coils, wherein each conductor of said interleaved array at a given axial location carries the same current, in the same direction, alternating in time in synchronism with the motion of the object so as to provide driving or braking forces as needed.

8. The magnet configuration of claim 7, wherein said array of one or more conductors is configured to not couple inductively to said coils, so that the centering and driving/braking functions are electrically independent of each other.

9. The magnet configuration of claim 1, wherein said first pair of Halbach arrays are substantially horizontally oriented, wherein said first component of said first magnetic field and said first component of said second magnetic field comprises a substantially vertical component, wherein said second component of said first magnetic field and said second component of said second magnetic field comprises a substantially horizontal component, wherein said first Halbach array is an upper array, and wherein said second Halbach array is a lower array relative to said upper array.

10. The magnet configuration of claim 9, wherein due to the downward force of gravity, a midplane between said first pair of Halbach arrays will lie below said track, wherein said restoring force will provide a net levitation force.

11. The magnet configuration of claim 9, wherein said first pair of Halbach arrays, when moving, have a characteristic lift-to-drag ratio at operating loads, wherein said lift-to-drag ratio can be further increased by increasing an area of said first pair of Halbach arrays to decrease the downward displacement required to levitate a given weight, and thus decrease the current required for levitation.

12. The magnet configuration of claim 9, wherein the current required to levitate said first pair of Halbach arrays may be further adjusted by making said lower array to be thinner with respect to said upper array.

13. The magnet configuration of claim 9, wherein the current required to levitate said first pair of Halbach arrays may be further adjusted by making said upper array wider with respect to said lower array.

14. The magnet configuration of claim 9, further comprising means for separating the function of generation of induced currents in said track from the function of providing levitation.

15. The magnet configuration of claim 14, wherein said means for separating the function of generation of induced currents in said track from the function of providing levitation comprises adding to said first pair of Halbach arrays a second pair of Halbach array with a magnet orientation such that the components of the field lying in the midplane between each array of said second pair of Halbach arrays cancel, while those perpendicular to the midplane add.

16. The magnet configuration of claim 15, wherein said second pair of Halbach arrays comprise end pole faces that point in a first direction perpendicular to said arrays, and center pole faces that point in the opposite direction from that of said first direction, and pole faces adjacent to said center pole faces that point toward the center poles of their respective Halbach array of said second pair of Halbach arrays.

17. The magnet configuration of claim 16, wherein said track comprises two substantially L-shaped circuits placed back-to-back, wherein said first pair of Halbach arrays is operatively positioned to provide levitating force against said track, wherein said second pair of Halbach array is operatively positioned to drive the levitating currents that power said first pair of Halbach arrays.

18. The magnet configuration of claim 1, wherein said windings comprise a planar array of conductors electrically connected together at their ends.

19. The magnet configuration of claim 1, wherein said track is tilted from the horizontal to provide a centering force.

20. The magnet configuration of claim 1, wherein said first Halbach array and said second Halbach array each comprise two outer poles that are pointed towards a midplane between said first Halbach array and said second Halbach array, wherein said first Halbach array and said second Halbach array each comprise a center pole that is pointed away from said midplane and poles adjacent to said center pole that point toward the center pole of the respective array.

21. The magnet configuration of claim 1, wherein the spacing between said first Halbach array and said second Halbach array is adjusted to increase or decrease the field between them, thus varying the levitation current induced in said track.

22. The magnet configuration of claim 21, further comprising an interleaved array of one or more conductors, symmetrically located with respect to the midplane of the said coils, wherein each conductor of said interleaved array at a given axial location carries the same current, in the same direction, alternating in time in synchronism with the motion of the object so as to provide driving or braking forces as needed.

23. The magnet configuration of claim 22, wherein said array of one or more conductors is configured to not couple inductively to said coils, so that the centering and driving/braking functions are electrically independent of each other.

24. The magnet configuration of claim 1, wherein said track comprises laminated sheets of conductor, wherein said sheets comprise slots terminated at their ends to provide a path for the return currents, wherein each conductor is individually loaded with elements that comprise strips of ferromagnetic material near the ends of the slots.

25. A method for generating a restoring force upon a magnet configuration, comprising;

providing a first Halbach array having a first magnetic field and a second Halbach array having a second magnetic field, wherein said first Halbach array and said second Halbach array are magnetically and structurally connected together to form a first pair of Halbach arrays, wherein said first Halbach array comprises magnet configurations positioned with respect said second Halbach array and said second Halbach array comprises magnet configurations positioned with respect said first Halbach array such that a first component of said first magnetic field and a first component of said second magnetic field substantially cancel at a first plane between said first Halbach array and said second Halbach array, and a second component of said first magnetic field and a second component of said second magnetic field substantially add at said first plane;

positioning a track of windings between said first pair of Halbach arrays;

moving said first pair of Halbach arrays along said track, wherein when said first pair of Halbach arrays move along said track and said track is not located at said first plane, a current is induced in said windings and a restoring force is exerted on said first pair of Halbach arrays; and

adjusting said restoring force.

26. The method of claim 25, wherein the step of adjusting said restoring force is carried out by a displacing process selected from a group consisting of (i) displacing said first Halbach array with respect to said second Halbach array and (ii) displacing said second Halbach array with respect to said first Halbach array.

27. The method of claim 25, wherein the step of adjusting said restoring force is carried out by an adjusting process selected from the group consisting of (i) adjusting a screw operatively positioned to mechanically displace said first Halbach array with respect to said second Halbach array and (ii) adjusting a screw operatively positioned to mechanically displace said second Halbach array with respect to said first Halbach array.

28. The method of claim 25, further comprising continuously adjusting said restoring force with a servo-control system, wherein said servo-control system continuously adjusts said restoring force in response to a command from a sensor attached to said vehicle.

29. A magnet configuration, comprising;

a first Halbach array having a first magnetic field and a second Halbach array having a second magnetic field, wherein said first Halbach array and said second Halbach array are magnetically and structurally connected together to form a first pair of Halbach arrays, wherein said first Halbach array comprises magnet configurations positioned with respect said second Halbach array and said second Halbach array comprises magnet configurations positioned with respect said first Halbach array such that a first component of said first magnetic field and a first component of said second magnetic field substantially cancel at a first plane between said first Halbach array and said second Halbach array, and a second component of said first magnetic field and a second component of said second magnetic field substantially add at said first plane;

a track of windings between said first pair of Halbach arrays;

a propulsion mechanism for moving said first pair of Halbach arrays along said track, wherein when said first pair of Halbach arrays move along said track and said track is not located at said first plane, a current is induced in said windings and a restoring force is exerted on said first pair of Halbach arrays,

wherein said track comprises a column of electrically connected coils that intercept no net flux when they are centered with respect to the Halbach arrays on either side but when there is a sidewise displacement, flux will be coupled, inducing currents in these circuits, which interact with the Halbach array nearest the circuit, and thereby providing a sideways centering force resulting from the Halbach array pushing away from the circuit, wherein said first pair of Halbach arrays is configured as the armature of a linear synchronous motor; and

a channel configuration iron rail having two lower pole faces operatively positioned above said first pair of Halbach arrays, wherein edge fields of said first pair of Halbach arrays are attracted to said two lower pole faces of said iron rail.

30. The magnet configuration of claim 29, further comprising means for adjusting said restoring force.

31. The magnet configuration of claim 30, wherein said means for adjusting said restoring force is selected from the group consisting of (i) means for displacing said first Halbach array with respect to said second Halbach array, and (ii) means for displacing said second Halbach array with respect to said first Halbach array.

32. The magnet configuration of claim 30, wherein said means for adjusting said restoring force is selected from a group consisting of (i) at least one adjusting screw operatively positioned to mechanically displace said first Halbach array with respect to said second Halbach array, and (ii) at least one adjusting screw operatively positioned to mechanically displace said second Halbach array with respect to said first Halbach array.

33. The magnet configuration of claim 30, further comprising a vehicle attached to said first pair of Halbach arrays, further comprising a sensor attached to said vehicle, wherein said means for adjusting said restoring force further comprises a servo-control system configured to adjust said levitation force in response to a command from said sensor.

34. The magnet configuration of claim 33, wherein said sensor is selected from the group consisting of a pitch sensor, a yaw sensor and a load sensor.

35. A method for generating a restoring force upon a magnet configuration, comprising;

providing a first Halbach array having a first magnetic field and a second Halbach array having a second magnetic field, wherein said first Halbach array and said second Halbach array are magnetically and structurally connected together to form a first pair of Halbach arrays, wherein said first Halbach array comprises magnet configurations positioned with respect said second Halbach array and said second Halbach array comprises magnet configurations positioned with respect said first Halbach array such that a first component of said first magnetic field and a first component of said second magnetic field substantially cancel at a first plane between said first Halbach array and said second Halbach array, and a second component of said first magnetic field and a second component of said second magnetic field substantially add at said first plane;

positioning a track of windings between said first pair of Halbach arrays;

moving said first pair of Halbach arrays along said track, wherein when said first pair of Halbach arrays move along said track and said track is not located at said first plane, a current is induced in said windings and a restoring force is exerted on said first pair of Halbach arrays; and

providing a channel configuration iron rail having two lower pole faces operatively positioned above said first pair of Halbach arrays, wherein edge fields of said first pair of Halbach arrays are attracted to said two lower pole faces of said iron rail.

36. The method of claim 35, further comprising adjusting said restoring force.