Optimal Pole Assignment Research Articles

An Inductor Current Sensorless Control Strategy Based on Modified VSG Method for Single-Phase Microgrid Application With Seamless Transfer Capability

This paper proposes an inductor current sensorless control strategy based on modified virtual synchronous generator (VSG) method for single-phase inverter-interfaced microgrid application. Firstly, the outer power loop with Q-U integral term is presented for output reactive power enhancement, and an inner voltage regulation loop based on luenberger state observer is proposed to reduce the inductor current sensor. Meanwhile, in order to improve the response speed of the observer, the luenberger observer is designed based on the optimal pole assignment method. Secondly, a seamless switching strategy based on the modified VSG method is proposed, which can realize the seamless transition between the island mode and grid-connected mode. Finally, a single-phase 3kW VSG prototype is built, and the effectiveness and correctness of the proposed control strategy is verified by the simulation and experimental results.

Robust Optimal Regional Closed-loop Pole Assignment over Positivity Conditions and Differential Evolution

The presented paper describes an optimal closed-loop pole assignment for a vast control feedback framework and structure. The main aim of this paper is a regional selection of the closed-loop central polynomial with additional flexibility and leeway for the following optimization procedure. The optimality of the approach is provided through the positivity condition of the quasi-convex spectral polynomial (QSP). The spectral polynomial presents the uncertainty and closed-loop characteristic of the feedback system. The derivation of the QSP is based on the characteristics of the uncertainty models and metrics with norm H∞. The structure of the controller is freely chosen and is also the subject of the optimization procedure. An objective function for the optimization algorithm Differential Evolution (DE) is presented in multi-criteria form and is directly composed of various QSP's. Such optimization of the objective function improves the transparence, computation expense and the regularity of the optimal/suboptimal solution.

Optimal Pole Assignment of Linear Systems by the Sylvester Matrix Equations

The problem of state feedback optimal pole assignment is to design a feedback gain such that the closed-loop system has desired eigenvalues and such that certain quadratic performance index is minimized. Optimal pole assignment controller can guarantee both good dynamic response and well robustness properties of the closed-loop system. With the help of a class of linear matrix equations, necessary and sufficient conditions for the existence of a solution to the optimal pole assignment problem are proposed in this paper. By properly choosing the free parameters in the parametric solutions to this class of linear matrix equations, complete solutions to the optimal pole assignment problem can be obtained. A numerical example is used to illustrate the effectiveness of the proposed approach.

Optimal Pole Assignment of Self-Balancing Robot System

Self-balancing robot is a multivariable, coupled, nonlinear dynamic system, using the optimal pole assignment which can give attention to both good dynamic characteristics and LQ optimal design technology robustness and other advantages. Emulation and real-time control are given to show the effectiveness of the presented method.

Spectral Abscissa Minimization when Algebraic Control of Unstable LTI-TDS

Optimal pole assignment minimizing the spectral abscissa when algebraic control of linear time-invariant time delay systems (LTI-TDS) is focused in this paper. We concentrate on algebraic controller design approach in the RMS ring resulting in delayed controllers as well. In the case of unstable delayed plants, the use a simple feedback loop results in a characteristic quasipolynomial instead of polynomial is obtained which means that the closed loop has an infinite spectrum. Thus, it is not possible to place all feedback poles to the prescribed positions exactly by a finite number of free controller parameters. The pole placement problem is translated to the minimization of the spectral abscissa which is a nonsmooth nonconvex function of free parameters in many cases. We initially solve the problem via standard quasi-continuous shifting algorithm followed by a comparative utilization of three iterative optimization algorithms; namely, Nelder-Mead algorithm, Extended Gradient Sampling Algorithm and Self-Organizing Migration Algorithm. Simulation control of an unstable LTI-TDS - the roller skater on the swaying bow - serves as an illustrative example for the algebraic control with the spectral abscissa minimization.

Optimal pole assignment for discrete-time systems via Stein equations

This study is concerned with designing a feedback gain to minimise a quadratic performance index with guaranteed pole locations for closed-loop discrete-time linear systems. Firstly, a method that shifts the open-loop poles to desired locations by using a parametric linear Stein equation is presented. Then a recursive approach is proposed to shift every eigenvalue of a discrete-time linear system separately without mode decomposition in each step. By using such method, it is required to solve a linear Stein matrix equation of low order in each step. The presented method yields a solution which is optimal with respect to a quadratic performance index that can be obtained explicitly. The attractive feature of this method comparing with existing results is that it enables solutions to complex problems to be easily found without solving any non-linear algebraic Riccati equations. Moreover, analytical solutions can be obtained which may have advantages in some design problems. Numerical examples illustrate the proposed approach.

Digital Current Control of a Voltage Source Converter With Active Damping of LCL Resonance

Inductance-capacitor-inductance (LCL)-filters installed at converter outputs offer higher harmonic attenuation than L-filters, but careful design is required to damp LCL resonance, which can cause poorly damped oscillations and even instability. A new topology is presented for a discrete-time current controller which damps this resonance, combining deadbeat current control with optimal state-feedback pole assignment. By separating the state feedback gains into deadbeat and damping feedback loops, transient overcurrent protection is realizable while preserving the desired pole locations. Moreover, the controller is shown to be robust to parameter uncertainty in the grid inductance. Experimental tests verify that fast well-damped transient response and overcurrent protection is possible at low switching frequencies relative to the resonant frequency

Discrete-Time Sliding-Mode Control for Processes with Time Delay and Its Application to Cooling Plate for Semiconductor Manufacturing

PID control has been mainly used over the past years among various kinds of modern processes, however, the advanced control for most recent industrial processes is playing a more important role that leads to resource saving, energy conservation, and upgrading. 0n the other hand, most personnel operating or maintaining machines are unaccustomed to deal the advanced control because of its complexity. For that reason, we propose the simple design method of the sliding-mode control (SMC) for such processes with time delay. The proposed method is the sliding-mode control using a disturbance observer with compensation for the "pade-approximation error" that does not satisfy the matching condition. Moreover, we propose the optimal pole assignment algorithm of the observer. The advantages of the proposed method are 1) good transient characteristics, 2) reduction of chattering, 3) high robust performance, and 4) simplicity in designing. Simulation and experimental results illustrate the effectiveness of the proposed method with applying to the cooling plate for semiconductor manufacturing.

245 産業用ロボットの制御ゲインの調整方法と自動調整システム(ロボットの制御III)(OS ロボットの制御)

This paper presents our Auto Tuning System which is to tune up the control gains to optimal values for industrial robots. A perfomance index is well defined so that it can represent the dynamical features of real robots aptly. The system is not only practically useful by itself, but also sophisticated when considering the analytically optimal pole assignment of a controlled system. Once a factory worker sets it going, Auto Tuning System tunes the control gains over the all required configurations and joints of a robot arm. While its operating, workers are completely free of observation.

Optimal pole assignment into specified regions and its application to rotating mechanical systems

AbstractThis paper considers a pole assignment problem to cluster all poles of a closed‐loop system into some specified regions by introducing the complex state for systems having an isotropic property and by using the Riccati equation. The algebraic relations for the distribution of the eigenvalues of a complex matrix are used in order to cluster the poles into specified regions, which guarantees the relative stability margin, e.g. uniform damping or uniform damping ratio. The proposed scheme is essentially a combination of the pole assignment approach and linear quadratic design, taking the advantages of both. A block modal control method—an extension of recursive pole assignment—is also developed for the vibration control of rotating systems by clustering the forward and backward modes in order. Vibration control simulations with an isotropic rotor—bearing system, a magnetic bearing system and a rotating circular disc are treated in order to demonstrate the advantages of the proposed method.

Modal control with variable feedback for structural vibration systems. 1st report. Proposal of variable velocity feedback methods.

A modal control with variable velocity feedback for structural vibration systems is proposed. In particular, two methods of variable velocity feedback are presented. The first method is a design in the actual domain and is based on the following idea : even if the number of velocities measured is less than the number of controlled modes, we only have to supply the ideal control input to the actuators by estimating the unobserved velocities. Therefore, the feedback gains change depending on each mode. The second method is a design in the modal domain and the orthogonality property of the modal coordinates is used in this method. These two methods not only realize an optimal pole assignment for the controlled modes, but also have no effect on the uncontrolled modes. Simulations of the active control of two mathematical models are carried out to verify the efficiency of these methods.

Model Control with Variable Feedback for Structural Vibration Systems : 2nd Report, Application of a Variable Velocity Feedback Method to Flexible Rotor Systems

Two variable velocity feedback control methods were proposed in the first report. One is the design in a actual domain and the other is the design in a modal domain. These two methods not only realize an optimal pole assignment for the controlled modes, but also have no effect on the uncontrolled modes. The latter method has a wide range of applications and a general character. We have applied these methods to a flexible rotor system. The test rotor is supported by linear actuators through bearing housings which we call active control bearings. There are three critical speeds, up to 3000 rpm. The variable velocity feedback control system design is based on an experimental modal analysis instead of a mathematical model. We have completely controlled three modes by means of a digital controller. The unbalance responses with variable velocity feedback are similar to the unbalance responses with an ideal model control.

Optimal Pole Assignment for Discrete Linear Regulator With Deterministic Disturbances

This paper presents the solution of the linear discrete optimal control to achieve poles assigned in a circular region and, meanwhile, accommodate deterministic disturbances. It is shown that by suitable manipulations, the problem can be reduced to a standard discrete quadratic regulator problem that simultaneously ensures: 1) closed-loop-poles all inside a circle centered at (β, 0) with a radius α, where |β| + α ≤ 1, 2) minimizes the cost functional, and 3) accommodates external input disturbance.

ON THE DESIGN OF ROBUST CONTROL SYSTEMS FOR DISTILLATION COLUMNS

Abstract The distillation column dynamics is very nonlinear, especially at high purity. Multivariable control system designs, which are essentially linear, may not be able to perform well at different operating conditions. This paper looks at three different multivariable design techniques—decoupling control, optimal state feedback and pole assignment as applied to distillation column control. Robustness of these techniques are analyzed by looking at the performance of these controllers at different operating conditions. Some interesting results are obtained.

Design of Optimal Modulation Controllers for Multiarea AC/DC Systems Using Eigenvalue Sensitivities

This paper develops a new technique for the design of optimal modulation controllers for multi-area ac/dc systems. The technique is based on optimal pole assignment using eigenvalue sensitivities. The basic feature of the proposed method is that both the diagonal and the off-diagonal elements of the weighting matrices are used for the eigenvalue assignment which results in increased design flexibility. The method is applied to the design of a modulation controller for a strongly interconnected three area ac/dc system. Dynamic simulation results presented in the paper show that the proposed modulation controller results in significant improvement of dynamic performance of the interconnected system.

Optimal pole assignment for a discrete linear regulator with constant disturbances

This paper presents the solution of the linear discrete optimal control problem to achieve poles assigned in a circular region and meanwhile accommodate constant but unknown disturbances. It is shown that, by suitable manipulations, the problem can be reduced to a standard discrete quadratic regulator problem, and therefore the solution can easily be obtained.

Output feedback optimization of multiple-input systems with assigned poles†

Abstract A method is presented to place a number of system eigenvalues by means of output feedback, and to use any remaining design freedom to minimize a specified performance functional. The solution for this combination of optimal control and pole assignment is shown to be similar to that for the complete state feedback case and uses a novel pole assignment algorithm.