2. 26-29 Nov. 2003 - Superconducting magnetic levitated bearings for rotary machines Superconducting magnetic levitated bearings for rotary machines 5 th International Symposium on Advanced Nova University of Lisbon Electromechanical Motion Systems Marrakech 1 A Leão Rodrigues leao@uninova.pt Layout  Brief description of superconductor materials  Calculation of magnetic levitation forces  Journal magnetic bearings design  Thrust magnetic bearings design  Levitation experiment  Conclusions

3. Discovery of Superconductivity Heike Kammerling Onnes in his Cryogenic Laboratory at Leiden University, Holland, 1911 5 th International Symposium on Advanced Nova University of Lisbon Electromechanical Motion Systems Marrakech 2 Hg 0,025 0,00 0,05 0,075 0,10 0,125 0,15  4 o 00 4 o 10 4 o 20 4 o 30 4 o 40 T ( K ) 10 -5  Onnes results Resistence 26-29 Nov. 2003 - Superconducting magnetic levitated bearings for rotary machines A i u T V Mercury Thermometer Liquid Helium Onnes Experiment

4. Magnetic Field Effect Superconductor State Normal State 0 T c T HcHc H(T)H(T) Magnetic Field 12 24 36 0 2 468 H c (kA/m) Leather (Pb) Mercury (Hg) Selenium(Sn) Indium(In) Thallium (Tl) T(K) Low Temperature Superconductors (LTS), or 1 st generation discovered until 1970. 5 th International Symposium on Advanced Nova University of Lisbon Electromechanical Motion Systems Marrakech 3 26-29 Nov. 2003 - Superconducting magnetic levitated bearings for rotary machines Onnes Experiment A i u T V Material Thermometer Liquid Helium H

5. 26-29 Nov. 2003 - Superconducting magnetic levitated bearings for rotary machines JcJc TcTc HcHc Current density, J Magnetic field, H Temperature, T 0 Superconductivity region Critical Surface Region of normal state The superconductivity state of a material is destroyed if one of the following parameters are out of the critical surface: Critical superconductivity (T C ) Critical magnetic field (H C ) Critical current density (J C ) Lost of Superconductivity Superconductor I S T c T Superconductor state Normal state 0 JcJc J(T)J(T) Current density 5 th International Symposium on Advanced Nova University of Lisbon Electromechanical Motion Systems Marrakech 4

6. 26-29 Nov. 2003 - Superconducting magnetic levitated bearings for rotary machines Meissner Effect 5 th International Symposium on Advanced Nova University of Lisbon Electromechanical Motion Systems Marrakech 5 Ferromagnetic Magnet picoseconds Metal t 0 A superconductor is a diamagnetic material Negative magnetic susceptibility Supercondutor Magnet In 1933, Walter Meissner and Robert Ochsenfeld observed that the magnetic flux was expelled from the interior of the superconductor. Supercondutor Persistent current Walter Meissner

7. 26-29 Nov. 2003 - Superconducting magnetic levitated bearings for rotary machines 5 th International Symposium on Advanced Nova University of Lisbon Electromechanical Motion Systems Marrakech 6 Bardeen Cooper Schiffer BCS Theory. In 1957 the scientists John Bardeen, Leon Cooper e John Schiffer, from Illinois University, presented a mathematical model that described the superconductivity phenomenon in the low temperature superconductors, called BCS theory. F F Cooper pair Electron 1 Electron 2 T < T c. Two free electrons when cooled down at temperature T<T c are attracted forming a Cooper pair. Then, the pair travels through the crystalline structure without touching it and therefore finding no resistance.

8. 5 th International Symposium on Advanced Nova University of Lisbon Electromechanical Motion Systems Marrakech 7 H Supercondutor increasing - M H HcHc 0 Type I superconductor  Type I superconductors attain abruptly the normal state for a given critical magnetic field H c - M H H c1 0 H c2 increasing Vortexes H Type II superconductor  Type II superconductors start attaining transition for a given critical magnetic field H c1. Vortexes are formed and for H c2 > H c1 the superconductivity is totally lost.

9. 26-29 Nov. 2003 - Superconducting magnetic levitated bearings for rotary machines Bednorz e Alex Muller, in IBM laboratories, near Zurique, in 1986. Crystalline structure of La 2 CuO 4 Transition curves of La 2 CuO 4 Tc = 20 K High Temperature Superconductors (HTS) 5 th International Symposium on Advanced Nova University of Lisbon Electromechanical Motion Systems Marrakech 8 In 1986, George Bednorz e Alex M ü ller, from IBM laboratories in R ü schliko (Switzerland), discovered a ceramic composite based in lanthanum, which was superconductor around the transition temperature of 20 K.

10. 26-29 Nov. 2003 - Superconducting magnetic levitated bearings for rotary machines YBCO Superconductor (Yttrium, barium and copper oxide) YBCO ceramic blocks YBCO ceramic rings YBCO ceramic disc Paul Chu discovered YBCO in 1987 at the University of Huston. Tc = 86 K 5 th International Symposium on Advanced Nova University of Lisbon Electromechanical Motion Systems Marrakech 2 YBa 2 Cu 3 O 7 Crystalline structure of YBCO O O O Ba Y Cu

11. 26-29 Nov. 2003 - Superconducting magnetic levitated bearings for rotary machines Superconductors evolution versus time 5 th International Symposium on Advanced Nova University of Lisbon Electromechanical Motion Systems Marrakech 10 Liquid nitrogen 77 K

12. 26-29 Nov. 2003 - Superconducting magnetic levitated bearings for rotary machines 5 th International Symposium on Advanced Nova University of Lisbon Electromechanical Motion Systems Marrakech 11 Superconducting Levitation Force Superconductor NdFeB Permanent Magnet Superconductor

13. 26-29 Nov. 2003 - Superconducting magnetic levitated bearings for rotary machines Superconductor materials applications Evolution of the superconductors materials application Source: ISIS – International Superconductivity Industry Summit. 1995200020102020 Electronics Energy - bearings Transportation Industry Instrumentation 5 th International Symposium on Advanced Nova University of Lisbon Electromechanical Motion Systems Marrakech 12 Year

14. 26-29 Nov. 2003 - Superconducting magnetic levitated bearings for rotary machines LEVITATION FORCE CALCULATION x z (mm) 02468 10 0.1 1 10 100 HTS REM z YBCO BSCCO Levitation force (mN) Computed Experimental t Measured levitation force between a HTS and a REM versus vertical distance z 5 th International Symposium on Advanced Nova University of Lisbon Electromechanical Motion Systems Marrakech 13 HTS material B magnet J induced Permanent magnet z y z t Levitation force F Liquid nitrogen t (mm) 05101520 25 0.1 5 10 BSCCO Levitation force (mN) 15 20 HTS t YBCO REM Thickness of bulk YBCO dependence on levitation force z = 5 mm x Maxwell stress method

15. 26-29 Nov. 2003 - Superconducting magnetic levitated bearings for rotary machines 5 th International Symposium on Advanced Nova University of Lisbon Electromechanical Motion Systems Marrakech 14

16. 26-29 Nov. 2003 - Superconducting magnetic levitated bearings for rotary machines Journal magnetic bearing design 5 th International Symposium on Advanced Nova University of Lisbon Electromechanical Motion Systems Marrakech 15 Shaft HTS cylinder NdFeB permanent magnet f = 9.7 N/cm 2 Force density distribution surface alongside the magnetic bearing Journal magnetic bearing layout Shaft Permanent magnet Superconducting ring Copper ring g Permanent magnet Superconducting ring Copper ring Commercial journal magnetic bearing

17. 26-29 Nov. 2003 - Superconducting magnetic levitated bearings for rotary machines Thrust magnetic bearing design a) Lower part (HTS) b)Upper part (PM) Layout of the thrust magnetic bearing HTS blocks Stabilization NdFeB blocks Air gaps 300 Thrust magnetic bearing flux plot NdFeB YBCO Liquid nitrogen Levitator Thrust magnetic bearing 5 th International Symposium on Advanced Nova University of Lisbon Electromechanical Motion Systems Marrakech 16 Liquid nitrogen

18. 26-29 Nov. 2003 - Superconducting magnetic levitated bearings for rotary machines Magnetic Levitation 5 th International Symposium on Advanced Nova University of Lisbon Electromechanical Motion Systems Marrakech 17

19. 26-29 Nov. 2003 - Superconducting magnetic levitated bearings for rotary machines Conclusions 5 th International Symposium on Advanced Nova University of Lisbon Electromechanical Motion Systems Marrakech 18 Maxwell stress method to evaluate levitation forces between a permanent magnet and a YBCO superconductor under zero field cooling was presented.  Results for magnetic pressures are of the order of 10 N/cm 2.  The method was applied to the design of journal and thrust bearings.  These devices are now commercially produced and the market expectation shows a broad and innovative potential of industrial application. 

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