| In most of the methods of balancing flexible rotors many times of test runs are usually required in order to calculate correction masses, which will cost a large amount of time and motive power (especially in the cast of large scale rotors). Peoples always wish to identify rotor unbalance with the vibration information obtained from the operating rotor, but there are no mature and practicable methods available yet. Therefore, the aim of this thesis is to carry on further study on the basis of the existing achievements in order that rotor unbalance can be identified on-line and rotor balancing without test runs can be completed on-site. Consequently, this thesis develops the following aspects:1. According to the structure of the active magnetic bearing (AMB) and the characteristic of the active magnetic executor (AME), the design methods of the AME and the power amplifier, and the selection of the magnetic material used in the AME are improved, which make AME have greater working electronic current and saturation magnetic flux density, and smaller volumn. Moreover, this thesis presents calibration methods about the electromagnetic force calibration, which can be used in laboratory conveniently.2. A nonlinear err formula about the electromagnetic force of AME is derived, and a new method which adopts numerical value integral in the simulate study of the rotor-exciter system is presented, which solves the nonlinear simulate study problem of the rotor-exciter system in which the unbalance excitation vibration and the electromagnetic excitation vibration are mutual coupling and makes the nonlinear characteristic analysis of the AME/AMB even more accurate and convenient. Through simulation and experiment study the various factors that influence the nonlinear characteristic of the AME are cleared, and the effect of the different frequency vibration of rotor on parameters identification input value (the part in the electromagnetic force corresponding excitation frequency) is discovered, and on the basis of the above, the reasonable working parameters extent of the AME is presented.3. On the basis of the rotor dynamics equation set up by combining d'Alemdert principle with Rize way, a new on-line identification method of dynamic parameters of rotor-bearing system by electromagnetic excitation is presented. The method need not change the rotation speed of the rotor as generally to obtain vibration information of the rotor, and avoid the identification difficulty which will arise when dynamic parameters of rotor-bearing system change with the rotation speed. Meanwhile, by adopting three order polynomial as Rayleigh function and treating rotor shaft as continue beam to set up rotor system mathematical model, the method is more accurate than the finite element method.4. When there are not measurement sensors at the place where the bearing is installed, the usual method is to substitute the rotor vibration near the bearing for at thebearing, which often brings about poor identification precision. Therefore, a new parameter identification method used on this condition is presented, and the simulation and experiment study of this thesis indicates that the new method improves the precision of parameter identification effectively.5. On condition that dynamic parameters of rotor-bearing system have been obtained, the method of flexible rotor unbalance identification is presented, which takes modal dynamic balancing as the criterion of balancing and needs not change the operating speed of the rotor in identification. Because the main low order modal unbalances have been balanced by an identification, even if the rotation speed of the rotor is changed, the rotor can keep up good balance situation. The simulation study indicates that the result of identification and balancing can satisfy the requirement of all speed balancing in very wide extent by an identification without tests run even if dynamic parameters of rotor-bearing system change with rotation speed greatly.6. An experiment system of the rotor and the... |
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