Control of vibrational field in an elastic vibration unit with DC motors and time-varying observer

In the paper the problem of feedback control of vibrational fields in a vibration unit is analyzed taking into account the influence of the elasticity of cardan shafts, the drive dynamics, saturation for control torques. In addition, the synthesized rotor synchronization control algorithm uses the estimates of a non-stationary observer, which makes it possible to implement it practically on a two-rotor vibration unit SV-2. The performance of the closed loop mechatronic systems is examined by simulation for the model of the two-rotor vibration unit SV-2.

Impact of the Field Winding Interturn Short-Circuit Position on Rotor Vibration Properties in Synchronous Generators

This paper investigates the effect of the field winding interturn short-circuit (FWISC) position on the rotor vibration properties in turbo generators. Different from the previous studies which focused on the influence of the short-circuit degree, this work pays much attention to the impact of the short-circuit position on the rotor unbalanced magnetic pull (UMP) properties and vibration characteristics. The theoretical UMP model is firstly deduced based on the analysis of the magnetic flux density (MFD) variation. Then, the finite element analysis (FEA) is performed to calculate the UMP data. Finally, the rotor vibrations are tested on a CS-5 prototype generator which has two poles and a rated capacity of 5 kVA. It is shown that the occurrence of FWISC will greatly increase the UMP as well as the rotor vibration. In addition to the short-circuit degree, the short-circuit position will also affect the UMP and vibration. The nearer the short-circuit position is to the big rotor teeth, the larger the UMP and vibration will be. The proposed study in this paper will be beneficial for the monitoring and diagnosis of FWISC faults.

The Influence of Ring-Speed Ratio Dynamic Change on Nonlinear Vibration Response of High-Speed Turbocharger Rotor System

The ring-speed ratio is a comprehensive dynamic index of floating ring bearing structure and operating parameters, which directly affects the dynamic behavior of the turbocharger rotor system. The cross stiffness of ring-speed ratio and floating ring bearing and the work of oil film force are analyzed. The influence of dynamic ring-speed ratio change on the vibration response of floating ring bearing was studied. The finite element model of the rotor-floating ring bearing system is constructed; its model parameters are verified through the measured critical rotor speed. Newmark integral method is used to analyze the nonlinear transient response. The results show that when the ring-speed ratio is between 0.18 and 0.24, the rotor is in a good operating state; when it increases from 0.24 to 0.36, the rotor vibration is dominated by frequency division, and the system will be less stable. The square of the ring-speed ratio is inversely proportional to the rotational speed of the journal where the subfrequency vibration occurs. It helps to know the nonlinear vibration by judging the journal speed when the rotor vibration occurs in subfrequency. The conclusion provides a reference for the mechanical dynamics design and intelligent management and maintenance of this kind of turbine rotors.

CONTROL OF PASSAGE THROUGH RESONANCE ZONE FOR 1-ROTOR VIBRATION UNIT WITH TIME-VARYING LOAD

The speed-gradient algorithms for controlled passage through the resonance zone of the one-rotor vibration unit are studied by computer simulation. The objective of the study is to analyze dependence of the control performance on the loading mode and the electric drive dynamics. In order to obtain an algorithm better suitable for practical implementation the theoretically designed algorithm is simplified by simplifying the expression for the total energy. First of all, we neglect the terms corresponding to the kinetic and potential energy of the load, since there are no load mass sensors on the stand. the term containing the inclination angle of the platform is neglected. In addition, the platform inclination angle and dynamics of the drives were neglected too. Efficiency of the proposed simplified algorithm for different loading modes, including linear loading with different loading rates and sine-shaped oscillatory loading.

Demonstration of Advanced Magnetic Technologies for a Highly Reliable and Retrievable Electric Submersible Pump Topology

This effort designs, builds and tests key enabling technology components of the magnetic drive system (MDS) electric submersible pump (ESP) concept, an advanced high speed ESP that differs from conventional ESP topologies in using magnetic technologies to increase reliability and retrievability. The enabling components include a radial passive magnetic bearing (PMB) system, allowing for a contact-less bearing system and remote removal of rotating components, and magnetic vibration sensors (MVS), enabling prognostics for higher reliability. An MDS ESP preliminary design has been developed through a DeepStar program, from which the size and integration requirements of the PMB and MVS have been defined. These requirements guide the analysis, design and testing of the full-scale components. Empirical analysis tools are used for initial iterations in size and performance of the PMB and MVS, followed by detailed magnetic finite element analysis (FEA) using commercial validated tools for the final performance prediction. With analytical validation of performance, detail designs are developed and hardware fabricated. Hardware testing is done to validate performance predictions and alignment with system requirements. The PMB performance results include testing of stiffness capability. These characteristics are used to validate the integration requirements for load capability and deflection during static load events, all in relation to validating performance for use in the MDS system. This test data is used to validate the analysis approach used as well as to finalize the integration size of the PMB to meet the performance requirements of the MDS system. To identify rotor operating speed and rotor vibration magnitude and frequencies, the MVS is tested for sensing rotor motion rate and frequency, including sub-synchronous and super synchronous frequencies. Identifying data reduction needs, i.e. how data is compiled and presented to focus on specific areas of interest, is also critical to determine the vibration characteristic of specific events happening in the ESP, such as bearing wear or dynamic fluid changes. Testing also includes variations in tubing materials to assess performance impact. These technologies offer bearing and sensor technologies that enhance ESP reliability and active performance monitoring. The PMBs offer a contact-less bearing system that does not require lubrication, can operate with large clearances to allow free fluid flow, and has no operating life limits. The compact MVS offers rotor vibration diagnostics throughout the ESP, including between pump stages, for monitoring performance, detecting ESP mechanical issues or process fluid variations allowing immediately response to increase operational life.

A Vibration Sensor-Based Method for Generating the Precise Rotor Orbit Shape with General Notch Filter Method for New Rotor Seal Design Testing and Diagnostics

Verification of the behaviour of new designs of rotor seals is a crucial phase necessary for their use in rotary machines. Therefore, experimental equipment for the verification of properties that have an effect on rotor dynamics is being developed in the test laboratories of the manufacturers of these components all over the world. In order to be able to compare the analytically derived and experimentally identified values of the seal parameters, specific requirements for the rotor vibration pattern during experiments are usually set. The rotor vibration signal must contain the specified dominant components, while the others, usually caused by unbalance, must be attenuated. Technological advances have made it possible to use magnetic bearings in test equipment to support the rotor and as a rotor vibration exciter. Active magnetic bearings allow control of the vibrations of the rotor and generate the desired shape of the rotor orbit. This article presents a solution developed for a real test rig equipped with active magnetic bearings and rotor vibration sensors, which is to be used for testing a new design of rotor seals. Generating the exact shape of the orbit is challenging. The exact shape of the rotor orbit is necessary to compare the experimentally and numerically identified properties of the seal. The generalized notch filter method is used to compensate for the undesired harmonic vibrations. In addition, a novel modified generalized notch filter is introduced, which is used for harmonic vibration generation. The excitation of harmonic vibration of the rotor in an AMB system is generally done by injecting the harmonic current into the control loop of each AMB axis. The motion of the rotor in the AMB axis is coupled, therefore adjustment of the amplitudes and phases of the injected signals may be tedious. The novel general notch filter algorithm achieves the desired harmonic vibration of the rotor automatically. At first, the general notch filter algorithm is simulated and the functionality is confirmed. Finally, an experimental test device with an active magnetic bearing is used for verification of the algorithm. The measured data are presented to demonstrate that this approach can be used for precise rotor orbit shape generation by active magnetic bearings.