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Satyabrata Das

Bio: Satyabrata Das is an academic researcher from National Institute of Standards and Technology. The author has contributed to research in topics: Rotor (electric) & Closed-loop pole. The author has an hindex of 1, co-authored 4 publications receiving 2 citations.

Papers
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Proceedings ArticleDOI
01 Mar 2019
TL;DR: This approach not only eases out the implementation of digital/analog realization of a Fractional Order PID (FOPID) controller with its integer order but at the same time it also preserves the advantages of fractional order controller.
Abstract: Rotating machines and its applications directly affect the basic economic issues and deals very closely with human life. Its safe operation is hence an absolute necessity. Rotors with speed higher than a specific threshold value become unstable due to rotating damping forces produced by the dissipation in rotor material, couplings or due to friction in tool-tips and splines. Some techniques do exist for stabilizing rotors however they are not well suited for small, micro and mini rotor systems. Orbital response function and 2-stage sub-optimal controller tuning methodology in rotor system actuated by a piezo actuator for providing adequate damping force has been used to keep the rotor stable. The approximated integer order PID gains thus obtained from conformal mapping-based FO method of stage 2 tuning pushes the closed loop poles of the system towards greater damping as compared to stage 1. This approach not only eases out the implementation of digital/analog realization of a Fractional Order PID (FOPID) controller with its integer order but at the same time it also preserves the advantages of fractional order controller. Simulation is done on MATLAB & SIMULINK. The analysis of the performances for both the cases are discussed.

1 citations

Proceedings ArticleDOI
01 Dec 2017
TL;DR: In this article, the authors used state feedback linearization and fractional order control for stabilizing the hydrodynamic journal bearing and integrated model of a rotor-hydrodynamic bearing system.
Abstract: Hydrodynamic journal bearings are one of the most widely used bearings to support the rotating shafts Rotating machines have a number of complicated accessories attached with it and they are also made extremely flexible Rotating machines are also required to run at higher speed, much higher than their first threshold speed Rotor-hydrodynamic journal bearing systems exhibit different kinds of phenomena pertaining to its operations Hydrodynamic journal bearing and integrated model tends to be unstable due to nonconservative nature of hydrodynamic forces and stiffness coefficients First, we linearized the non-linear system using state feedback linearization Second, optimal and fractional order control methods are used for stabilizing the integrated system Modeling and simulation are done by using MATLAB-Simulink programming The performances are discussed for both cases

1 citations

Journal ArticleDOI
30 Dec 2018
TL;DR: In this article, a piezo electrical type of actuating system for applying damping force to the rotating shaft by implementing a smart embedded coupling which rotates along with the rotor was proposed.
Abstract: Destabilizing effects due to rotating damper’s in a gyrating or spinning systems is a very common phenomenon. Rotor’s at speed higher than certain threshold values become unstable due to rotating damping forces generated by dissipation in rotor materials, coupling or due to friction in spline’s and tool tip’s. Presently the current methods are mostly passive and suitable for large or medium size rotor’s but not quite applicable for small, mini or micro rotor systems. This paper uses an alternative technique to stabilize rotors of any size and description. The authors propose a piezo electrical type of actuating system for applying damping force to the rotating shaft by implementing a smart embedded coupling which rotates along with the rotor. The stabilization control was implemented by designing a simple state feedback Linear Quadratic Regulator whose gains were determined and applied to the rotor shaft through proposed smart embedded coupling.
Journal ArticleDOI
TL;DR: In this paper, the authors proposed a control strategy to stabilize non-rigid rotors having flexible modes. And the stabilizing algorithm was designed by keeping the overall control law mathematically simple such that the minimum number of sensors were used and deployed.
Abstract: In this paper there is an attempt to develop an elegant controlling strategy to stabilize flexible rotors having flexural modes. Initially, the possible causes of instability in a rotor system due to internal damping through mathematical formulation are discussed. The threshold or the critical speed was derived beyond which the rotor became unstable. The stabilizing algorithm was designed by keeping the overall control law mathematically simple such that minimum numbers of sensors were used and deployed. Actuators were properly selected such that control and stabilization was practically possible for rotors of such low diameters. Bond graphs were used to model the rotor system having flexural modes. As bond graphs act as a portrayal of power and information exchange within the system and with external environment, bond graphs may give a better clue for modeling such systems. The real challenge in this work lies in the proposal of control strategy in stabilizing non-rigid rotors having flexible modes. Mathematical simplicity of the proposed control algorithms is considered for its easy deployment. The Simplest Beam model the Euler-Bernoulli beam is considered.

Cited by
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Journal ArticleDOI
TL;DR: In this paper, the vibration control of induction motors with sleeve bearings, mounted on soft steel frame foundations, using active motor foot mounts, is analyzed, based on a multibody model, considering electromagnetic influence, stiffness, and rotating damping of the rotor, stiffness of the bearing housings with end shields, and of the oil film in the sleeve bearings.
Abstract: 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.

3 citations