Transactions of the Korean Society of Mechanical Engineers A (대한기계학회논문집A)

The Korean Society of Mechanical Engineers (대한기계학회)
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Predictions of Unbalanced Response of Turbo Compressor Equipped with Active Magnetic Bearings through System Identification

시스템 식별을 통한 자기베어링 장착 터보 압축기의 불평형 응답 예측

  • 백성기 (충남대학교 메카트로닉스공학과) ;
  • 노명규 (충남대학교 메카트로닉스공학과) ;
  • 이기욱 (LG 전자 AE 연구센터) ;
  • 박영우 (충남대학교 메카트로닉스공학과) ;
  • 이남수 (LG 전자 AE 연구센터) ;
  • 정진희 (LG 전자 AE 연구센터)
  • Received : 2015.07.03
  • Accepted : 2015.11.27
  • Published : 2016.01.01
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Abstract

Since vibrations in rotating machinery is a direct cause of performance degradation and failures, it is very important to predict the level of vibrations as well as have a method to lower the vibrations to an acceptable level. However, the changes in balancing during installation and the vibrational modes of the support structure are difficult to predict. This paper presents a method for predicting the unbalanced response of a turbo-compressor supported by active magnetic bearings (AMBs). Transfer functions of the rotor are obtained through system identification using AMBs. These transfer functions contain not only the dynamics of the rotor but also the vibrational modes of the support structure. Using these transfer functions, the unbalanced response is calculated and compared with the run-up data obtained from a compressor prototype. The predictions revealed the effects of the support structure, validating the efficacy of the method.

회전 기계에서 회전에 따른 진동은 성능 저하 및 고장의 직접적 원인이 되어, 진동을 예측하고 저감 방안을 수립하는 것이 매우 중요하지만, 회전 기계의 조립이나 설치 과정에서 발생하는 불평형의 변화나 지지 구조물의 진동 모드는 예측이 어려워 그 영향을 사전에 평가하기 어렵다. 본 논문에서는 자기베어링에 의해 지지된 터보 압축기의 전달함수를 시스템 식별과정을 통해 구하고 이를 활용하여 압축기의 불평형 응답을 예측한다. 식별된 전달함수는 회전체의 진동 모드와 지지 구조물의 진동 모드를 함께 포함하고 있어, 불평형 응답에 대한 지지 구조물의 영향을 실질적으로 평가할 수 있다. 저속 운전에 의해 불평형을 추정하고 정격 속도까지의 불평형 응답을 시험 결과와 비교하여 예측의 적절성과 문제점을 파악하였다.

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References

  1. ISO Standard 7912, Mechanical Vibration of Non-Reciprocating Machines - Measurements on Rotating Shafts and Evaluation Criteria, 1996.
  2. Zhou, S. and Shi, J., 2011, "Active Balancing and vibration Control of Rotating Machinery: a Survey," Shock and Vibration Digest, Vol. 33, No. 5, pp. 361-371. https://doi.org/10.1177/058310240103300501
  3. Schweitzer, G. and Maslen, E. H., eds., 2009, Magnetic Bearings, Springer, New York.
  4. Yoo, S. and Noh, M., 2013, "Comparative Study of Performance of Switching Control and Synchronous Notch Filter Control for Active Magnetic Bearings," Trans. Korean Soc. Mech. Eng. A, Vol. 37, No. 4, pp. 511-519. https://doi.org/10.3795/KSME-A.2013.37.4.511
  5. Tiwari, R. and Chougale. A., 2014, "Identification of Bearing Dynamic Parameters and Unbalance States in a Flexible Rotor System Fully Levitated on Active Magnetic Bearings," Mechatronics, Vol. 24, No. 3, pp. 274-286. https://doi.org/10.1016/j.mechatronics.2014.02.010
  6. Sinha, J. K., Friswell, M. I. and Lees, A. W., 2002, "The Identification of the Unbalance and the Foundation Model of a Flexible Rotating Machine from a Single Run-Down,", Mechanical Systems and Signal Processing, Vol. 16, No. 2, pp. 255-271. https://doi.org/10.1006/mssp.2001.1387
  7. Simulink Real-Time$^{TM}$, The Mathworks Corporation, Cambridge, USA.
  8. Franklin, G., Powell, J. and Workman, M., 1990, Digital Control of Dynamic Systems, 2nd ed., Addison Wesley, Reading, MA, USA.
  9. ISO Standard 14839-3, Mechanical Vibration - Vibration of Rotating Machinery Equipped with Active Magnetic Bearing: Part 3 - Evaluation of Stability Margin, 2006.
  10. Cloud, C., Li, G., Maslen, E. and Barret, L., 2005, "Practical Applications of Singular Value Decomposition in Rotordynamics," Australian J. Mech. Eng., Vol. 2, pp. 21-32. https://doi.org/10.1080/14484846.2005.11464477