VFD Machinery Vibration Fatigue Life and Multilevel Inverter Effect

This paper documents fatigue-related mechanical failures in variable-frequency drive (VFD) motor machinery due to mechanical vibrations excited by drive torque harmonics which are created by pulse width modulation (PWM) switching. Present effort models the coupled system with a full electrical system (including the rectifier, dc bus, inverter, and motor), and an industrial mechanical system (including flexible couplings, gearboxes, and multiple inertias). The models are formed by a novel combination of a commercial motor code with a general self-written mechanical code. The approach extends failure prediction beyond the simple occurrence of resonance to fatigue life evaluation based on the rain-flow algorithm, which is suitable for both steady state and transient start-up mechanical response. The second contribution is a demonstration that the common use of a multilevel inverter to reduce voltage/current harmonics may actually exacerbate resonance and fatigue failure. This is shown to be caused by a resulting amplitude increase of torque components in proximity to potential resonance frequencies.

[1]  J. C. Wachel,et al.  Analysis Of Torsional Vibrations In Rotating Machinery. , 1993 .

[2]  John A. Kocur,et al.  VFD Induced Coupling Failure , 2008 .

[3]  S. Wang,et al.  Mean Shear Stress Effect for a Notch-Free Ductile Material Under Pure Cyclic Torsional Loads , 2006 .

[4]  Muhammad H. Rashid,et al.  Power Electronics Handbook: Devices, Circuits and Applications , 2010 .

[5]  Uwe Schaefer,et al.  Torque ripple in PWM-VSI-fed drives due to parasitic effects in the inverter control , 2009, 2009 35th Annual Conference of IEEE Industrial Electronics.

[6]  Thomas H. Barton,et al.  Start-Up Torques in Synchronous Motor Drives , 1978, IEEE Transactions on Industry Applications.

[7]  Troy Feese,et al.  Torsional Vibration Problem with Motor/ID Fan System Due to PWM Variable Frequency Drive , 2008 .

[8]  Si Young Jung,et al.  A torsional vibration analysis of synchronous motor driven trains by the modal method , 1986 .

[9]  Lazhar Ben-Brahim,et al.  Novel Torque Ripple Minimization Control For 25 MW Variable Speed Drive System Fed By Multilevel Voltage Source Inverter , 2010 .

[10]  D. J. Sheppard.  Torsional vibration resulting from adjustable-frequency AC drives , 1988 .

[11]  Seçil Arıduru,et al.  Fatigue life calculation by rainflow cycle counting method , 2004 .

[12]  E. J. Gunter,et al.  Introduction to Dynamics of Rotor-Bearing Systems , 2005 .

[13]  Muhammad H. Rashid,et al.  Power electronics handbook , 2001 .

[14]  Ryan J. Kari,et al.  Magnetic means for determining torsional yield strength , 2003 .

[15]  D.G. Holmes,et al.  A general analytical method for determining the theoretical harmonic components of carrier based PWM strategies , 1998, Conference Record of 1998 IEEE Industry Applications Conference. Thirty-Third IAS Annual Meeting (Cat. No.98CH36242).

[16]  Gabriel Ekemb,et al.  Prediction of Mechanical Shaft Failures Due to Pulsating Torques of Variable-Frequency Drives , 2010, IEEE Transactions on Industry Applications.

[17]  Shirley Dex,et al.  JR 旅客販売総合システム（マルス）における運用及び管理について , 1991 .

[18]  Leon M. Tolbert,et al.  17 – Multilevel Power Converters , 2007 .

[19]  Thomas L. Paez,et al.  Random Vibrations: Theory and Practice , 1995 .

[20]  R.J. Kerkman,et al.  PWM inverters producing torsional components in AC motors , 2008, 2008 55th IEEE Petroleum and Chemical Industry Technical Conference.

[21]  J. Keith Nisbett,et al.  Shigley's Mechanical Engineering Design , 1983 .

[22]  Edgar F. Merrill,et al.  Oscillatory Torques During Synchronous Motor Starting , 1970 .

[23]  G. G. Stokes.  "J." , 1890, The New Yale Book of Quotations.