TY - CHAP A1 - Werner, Ulrich ED - Werner, Ulrich T1 - Stability analysis of induction rotors supported in sleeve bearings considering electromagnetic field damping and internal material damping of the rotor T2 - Vibrations in Rotating Machinery N2 - The paper shows an analytical rotordynamic model for stability analysis of induction rotors, supported in sleeve bearings, especially considering the influence of electromagnetic field damping and internal material damping of the rotor. The model contains radial and tangential electromagnetic forces considering electromagnetic field damping, stiffness and internal material damping of the rotor structure, stiffness and damping of the support, and stiffness and damping of the oil film of the sleeve bearings. The aim is to unite all these influences in one analytical model and to derive a procedure for calculating the limit of rotor stability. KW - Induction rotors KW - Internal damping of rotor KW - Electromagnetic field damping KW - Sleeve bearings KW - Vibration stability analysis Y1 - 2016 UR - https://www.researchgate.net/publication/308208020 SN - 978-0-9572374-8-3 ER - TY - CHAP A1 - Werner, Ulrich ED - Werner, Ulrich T1 - Increasing the threshold of vibration stability of soft mounted induction motors with elastic rotors and sleeve bearings using active motor foot mounts T2 - Proceedings of ISMA2018 including USD2018 N2 - In the paper, the threshold of vibration stability of induction motors with flexible shafts and sleeve bearings, mounted on soft steel frame foundations with active motor foot mounts, is analyzed. The developed model is based on a multibody model, considering electromagnetic influence, stiffness and internal damping of the rotor, stiffness and damping of the bearing housings and end shields, stiffness and damping of the foundation and stiffness and damping of the oil film of the sleeve bearings. Additionally the stiffness and damping of the motor foot mounts – which are positioned between the motor feet the soft steel frame foundation – are considered, as well as the controlled forces which are applied in the vibration system by the motor foot mounts, using PD-controllers. The aim of the paper is to unite all these influences in a mathematical model and to derive a procedure for calculating the threshold of vibration stability. Based on a numerical example it can be shown, that the threshold of stability can be pushed to very high rotor speeds, using active motor foot mounts. KW - Induction motors KW - Active vibration control KW - Threshold of stability KW - Sleeve bearings KW - Motor foot mounts Y1 - 2018 UR - https://past.isma-isaac.be/downloads/isma2018/proceedings/Proceedings_ISMA-USD2018.pdf ER - TY - CHAP A1 - Werner, Ulrich ED - Werner, Ulrich T1 - Influence of dynamic magnetic eccentricity on sleeve bearing housing vibrations of induction motors considering electromagnetic field damping N2 - The paper shows the influence of dynamic magnetic eccentricity on the sleeve bearing housing vibrations of induction motors, considering electromagnetic field damping. The analytical model contains electromagnetic forces in respect of electromagnetic field damping, stiffness and internal (rotating) damping of the rotor, dynamic magnetic eccentricity, stiffness and damping of the support, and stiffness and damping of the oil film of the sleeve bearings. Based on an analytical rotordynamic model, a practicable method is presented, showing how to consider electromagnetic field damping, when analyzing forced vibrations caused by dynamic magnetic eccentricity, which can also be adopted in a Finite-Element-Analysis. KW - Induction motors KW - Dynamic magnetic eccentricity KW - Electromagnetic field damping KW - Sleeve bearings KW - Bearing housing vibrations Y1 - 2017 UR - https://www.researchgate.net/publication/318307655 ER - TY - CHAP A1 - Werner, Ulrich ED - werner, ulrich T1 - Calculation procedure to derive the threshold of vibration stability of soft mounted induction motors with elastic rotors and sleeve bearings fixed on active motor foot mounts for arbitrary controller structures T2 - 12th International Conference on Vibrations in Rotating Machinery N2 - In the paper an iterative calculation procedure is presented for deriving the threshold of vibration stability of induction motors with flexible shafts and sleeve bearings, mounted on soft steel frame foundations with active motor foot mounts and arbitrary controller structures. The mathematical model considers the electromagnetic influence, stiffness and internal damping of the rotor, stiffness and damping of the bearing housings with end shields, of the foundation and of the oil film of the sleeve bearings, as well as the stiffness and damping of the motor foot mounts and the controlled forces, which are applied by the motor foot mounts. KW - Induction motors KW - Active vibration control KW - Stability analysis KW - Sleeve bearings KW - Motor foot mounts Y1 - 2020 UR - https://www.taylorfrancis.com/chapters/oa-edit/10.1201/9781003132639-27 SN - 9781003132639 CY - CRC Press ER - TY - JOUR A1 - Werner, Ulrich ED - werner, ulrich T1 - Vibration control of soft mounted induction motors with sleeve bearings using active motor foot mounts: a theoretical analysis JF - Archive of Applied Mechanics N2 - In the paper, the vibration control of induction motors with sleeve bearings—mounted on soft steel frame foundations—using active motor foot mounts is analyzed. The presented model is based on a multibody model, considering electromagnetic influence, stiffness, and rotating damping of the rotor, stiffness and damping of the bearing housings with end shields, of the oil film in the sleeve bearings, and of the foundation. Additionally, the stiffness and damping of the motor foot mounts—which are positioned between the motor feet and the steel frame foundation—are considered, as well as the controlled forces which are applied in the vibration system by the motor foot mounts, using PD-controllers. The aim of the paper is to unite all these influences in a mathematical model, including the control system. Based on a numerical example, it can be shown that the vibration behavior of soft mounted induction motors can be clearly improved and that critical speeds in the speed range can be avoided, using active motor foot mounts. KW - Induction motor KW - Active vibation control KW - Motor foot mounts KW - Sleeve bearings Y1 - 2019 U6 - https://doi.org/10.1007/s00419-018-1393-7 VL - 88 PB - Springer ER - TY - JOUR A1 - Werner, Ulrich ED - werner, ulrich T1 - Analysis of Different Vibration Control Strategies for Soft Mounted Induction Motors with Sleeve Bearings Using Active Motor Foot Mounts JF - JAMP-Journal of Applied Mathematics and Physics N2 - The paper presents a theoretical analysis of different vibration control strategies of soft mounted induction motors with sleeve bearings, using active motor foot mounts. After the vibration model is presented, different controllers in combination with different feedback strategies are mathematically investigated. The focus is here on the forced vibrations, caused by dynamic rotor eccentricity—rotor mass eccentricity, magnetic eccentricity and bent rotor deflection. After the mathematically coherences are described, a numerical example is shown, where the forced vibrations caused by bent rotor deflection are investigated, for different control strategies, where the mass matrix, the stiffness matrix and the damping matrix are influenced by different control parameters. The aim of the paper is to show the mathematically coherences and the possibility to influence the vibration behaviour, by different control strategies to optimize the vibration behaviour of soft mounted induction motors. KW - Induction motor KW - Active vibation control KW - Motor foot mounts KW - Sleeve bearings KW - Different control strategies Y1 - 2019 U6 - https://doi.org/10.4236/jamp.2019.73045 VL - 7 IS - 3 PB - Scientific Reseach ER - TY - JOUR A1 - Werner, Ulrich ED - werner, ulrich T1 - State space model for vibration control with arbitrary controller structures for soft mounted induction motors with sleeve bearings fixed on active motor foot mounts JF - ZAMM- Journal of Applied Mathematics and Mechanics N2 - In the paper, a state space model for vibration control with arbitrary controller structures for soft mounted induction motors with sleeve bearings fixed on active motor foot mounts is shown. Besides the mathematical description of the forced vibrations caused by dynamic rotor eccentricity, a procedure is presented to derive the threshold of vibration stability. The challenge of the paper is the use of arbitrary controller structures with different feedback strategies – feedback of the motor feet displacements, velocities or accelerations – in combination with a special vibration system. This specialty is, that the stiffness and damping matrices depend on the rotor angular frequency Ω, which corresponds to the excitation angular frequency, when analyzing the forced vibration, and depend additionally on the natural angular frequency 𝜔 stab of the critical mode, when analyzing the threshold of stability. After the mathematical description is shown, a numerical example of a 2-pole induction motor (power rating 2.4 MW) is presented, in which the threshold of stability is analyzed as well as the forced vibrations due to dynamic rotor eccentricity by investigating the bearing housing vibrations, the foundation vibrations and the actuator forces. KW - Induction motor KW - Active vibation control KW - State space model KW - Sleeve bearings KW - Motor foot mounts Y1 - 2019 U6 - https://doi.org/10.1002/zamm.201900126 SN - 1521-4001 VL - 99 IS - 12 PB - Wiley ER -