Research On Permanent Magnet Biased Magnetic Bearing

The bias magnetic field of permanent magnet biased magnetic bearings (PMB) is created bypermanent magnets so that the power consumption is reduced, the space and weight is minimized.Besides, the power amplifiers of each degree freedom reduce to1, which improves its reliability andmakes it well suited for flywheel storage applications. Due to the characteristics and applications ofPMB, in this paper the various PMB are researched, such as homopolar, heterpolar, axial-radial andaxial, their topological structures, parameters design and optimization, magnetic fields analysis,experiment are also studied.The homopolar permanent magnet biased radial magnetic bearings (PRMB) is of low hysteresisloss, convenient control method and wide application. In the paper several topological homopolarPRMB are analyzed, A novel homopolar PRMB is studied, it's precise equivalent magnetic circuit isestablished based on2-D Finite Element simulation due to the influence from the equivalent magneticcircuit to the theoretical analysis and parameter design, and get the mathematical model of the radialmagnetic suspension force, the displacement stiffness and current stiffness. A parameter designmethod is presented, in which the relationship between both the bias and control magnetic flux andthe suspension bearing force is figured out, the parameters of stator and rotor are designed, theoptimization of permanent magnet based on engineering practicing is proposed, the affect of magneticreluctance coefficient and magnetic leakage coefficient are considered. The parameters of theproposed prototype are given, the3-D magnetic field simulation and experiment are accomplished,the rotor is suspended stably from0to20000r/min. The results show that the homopolar PRMB hassmaller volume and it's control is easier, the levitation performance is well and the parameter designmethod is rationalComparing to the homopolar PRMB, the heterploar PRMB has more simple structure and shorteraxial length. In this paper several topological heterploar PRMB are analized, especially a kind ofheterpolar PRMB with8magnetic poles, of which the parameter designing method and the influenceby the value of air-gap's bias flux density to it's structure and performance are studied. The3-Dmagnetic field simulation of the designing consequence is done, while the experiment platform of aheterploar PRMB with2-D freedom is also completed, by which the stable suspension speeding from0to7200r/min is achieved. It shows in both theoretical and experimental consequence that theheterploar PRMB has smaller volume and shorter axial length, the bias and control magnetic field are in the same plane, but the permanent magnet poles without active control is more influential to thesuspension performance.Making full use of the permanent magnet's magnetic energy, the structure becomes tight. In thispaper, by researching deeply on the permanent magnet biased axial radial magnetic bearings (PARMB)of classic structure, the paper puts out a PARMB with a novel structure. The biased magnetic field isproduced by the two permanent magnet rings located on both sides of rotor, the structure is very tightand the axial stator is out of the radial stator, so the axial control flux and the radial control flux aredecoupling. In the paper, the theoretical model and the parameter design are studied deeply, the3-Dsimulation analysis and experiment are done, the consequence shows that the PARMB makes full useof the permanent magnet's magnetic energy, the structure is tight, the control is simple, but the designand install are difficult.The permanent magnet biased axial magnetic bearings (PAMB) is of simple structure andindependent control method. The paper puts out a novel PAMB and its low power dissipation controlstrategy with asymmetric air gap, detailed theoretical analysis and parameter design process. The3-Dfinite element analysis simulation shows that the novel PAMB is of tight structure and convenientcontrol method, and comparing to the symmetric air gap structure, the suspension power loss deducesacutely. Combining it to the permanent magnet bearings, the system can satisfy the strict requirementsof the green power equipments' support component like flywheel storage system.To better verify the research consequence of PMB in former chapters and due to the speedlocalization of the former two experimental platforms, a5-degrees freedom PMB system with thesame PARMB is put out and manufactured, driven by the Switched Reluctance Motor, the shaft canreach a stable suspension at speed from0to36000r/min. The experimental consequence achieves abetter verification that the structure and the parameter design is reasonable, establishing a greatfoundation for industrial application.