Routh Approximation is believed to witness tremendous usage in deriving the reduced models from their higher equivalents. Order reduction is a critical field of interest for researchers or control engineers dealing with practical and physical systems of higher order. Reason for the popularity of Routh Approximation among other reduction methodologies is its strength of computational simplicity, ease of access and the promise to retain the model stability. This paper accomplishes a survey of the available Routh Approximation algorithms in their varied configuration since five decades. Last survey report based on Routh Approximation was cited in late seventies as discussed in the paper. One prime reason for the outcome of this paper is the problem met by the authors during their own work for analysing varied configuration of Routh Approximation for order reduction. Many times, the arrangement, stated or performed, seemed to be already in existence. Thus, the paper would be helpful to the researchers...

Order Reduction Techniques via Routh Approximation: A Critical Survey

In this paper a new frequency-domain model order reduction method is proposed for the reduction of higher-order linear continuous-time single input single output systems using a recent hybrid evolutionary algorithm. The hybrid evolutionary algorithm is developed from the mutual synergism of particle swarm optimization and differential evolution algorithm. The objective of the proposed method is to determine an optimal reduced-order model for the given original higher-order linear continuous-time system by minimizing the integral square error (ISE) between their step responses. The method has significant features like easy implementation, good performance, numerically stable and fast convergence. Applicability and efficacy of the method are shown by illustrating an IEEE type-1 DC excitation system, and by a typical ninth-order system taken from the literature. The results obtained from the proposed algorithm are compared with many familiar and recent reduction techniques that are available in the literature, in terms of step ISE values and impulse response energies of the models. Furthermore step and frequency responses are also plotted.

A Novel Model Order Reduction Technique for Linear Continuous-Time Systems Using PSO-DV Algorithm

This research work proposes a method to obtain a stable reduced-order interval model from its stable higher-order interval plant. The reduced-order interval numerator and denominator polynomials are determined by using Kharitonov’s polynomials and a general form of the Routh approximation method. The proposed reduction algorithm retains stability and full impulse response energy of the higher-order interval system in its reduced-order interval model. In addition to this, the proposed method has useful features like matching of time moments and mathematical simplicity. Moreover, a few numerical examples in the literature are taken into consideration and simulated through MATLAB to illustrate the effectiveness of the proposed method.

Impulse energy approximation of higher-order interval systems using Kharitonov’s polynomials:

To extract important information about the nonlinear signals, this letter makes the utmost of the fitting advantages of Gaussian and polynomial functions, and proposes a nonlinear signal model with broader applications. Then we focus on the parameter estimation issues of the proposed models in the presence of noises. The stability factor recursive algorithm is devised based on the increasing noisy data, which makes full use of the information from the nonlinear signals. Applying the hierarchical identification principle, a two-stage recursive algorithm with higher computational efficiency is developed for the nonlinear signals. The simulation results test the effectiveness of the proposed algorithms from the aspects of estimation accuracy and prediction effect.

Fitting Nonlinear Signal Models Using the Increasing-Data Criterion

A stepper motor is an electro mechanical device that can convert electrical pulses to the axis of movement. The finding problem  in the movement of a stepper motor is  cannot respond to the clock signal directly because the motor windings require a clock (sequence) in the correct order. If the control signal given is not correct, the motor is not moving according to the specified precision. To answer these problems, it is necessary to move the stepper motor with a clock signal that works in real time. The research method is done by designing and testing the stepper motor movement in full stepp and half step with the direction of Clock Wise (CW) and Counter Clock Wise (CCW) movement. These are simulated by using FPGA Isim and implementation using a stepper motor. The results of several experiments have been carried out the stepper motor movement degree according to the input value entered,responding timely movement, and the direction of movement stepper motor.

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Stepper motor movement design based on FPGA

All industrial drives need a controlled output and it can be achieved by controlling the input supply. In this regard, the inverter circuit plays an important role in the applications of industrial drives. The industrial drives are operated at high rated power and the conventional inverters cannot be applicable for high power demands because of the large dV/dt (rate of change of voltage) and more switching losses. Therefore, multilevel inverters are introduced for high power-medium voltage applications. For all AC drives the MLIs are reliable in operation. This MLI topology also reduces the harmonics and bearings stress of a motor with low dV/dt. In most applications multilevel inverters are used because we can get more number of voltage levels. To increase the number of voltage levels, circuit needs to have more switches. But, we have to optimize the switch count and switching operations. The power level of the inverter is limited due to high currents and stress. In this paper, we proposed a new circuit topology which enables the switches to be active at different voltage levels, causes reduction of the switching losses and also increases the efficiency of the inverter. In this we have presented two configurations for an eleven level MLI for three phase induction motor drive application. In this an individual DC source is connected for each bridge circuit of each phase in one configuration and only one common DC link is used for three phases in another configuration. With this the size, cost and complexity could be decreased. In both the configurations the controlled output of the inverter is connected to the induction motor drive. The circuits are modeled using Matlab/simulink software and corresponding output waveforms are analyzed for both configurations.

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A Novel Three Phase Multilevel Inverter with Single Dc Link For Induction Motor Drive Applications

This paper describes a technique to obtain a stable lower order Interval model from its stable higher order interval plant. The reduced order interval numerator and denominator polynomials are determined by using Kharitonov's theorem and Routh Approximation Method. The algorithm is simple, rugged and generates stable reduced order interval model for stable original high order interval plants. A numerical example illustrates the effectiveness of proposed algorithm.

Model reduction of linear interval systems using Kharitonov's polynomials

A new computationally simple and precise model approximation method is described for large-scale linear discrete-time systems. By least squares matching of a suitable number of time moment proportionals and Markov parameters about (z−1) of the original higher order system within the approximate model, stable denominator polynomial coefficients of the approximate model are determined. To improvise the accuracy of the approximate model, numerator polynomial coefficients are determined by minimizing the integral squared error (ISE) between the unit impulse responses of the original system and its approximate model. A matrix formula is formulated for evaluating numerator coefficients of the approximate model that leads to minimum ISE, and also for evaluating ISE. The efficacy of the proposed method is shown by illustrating three typical numerical examples employed from the literature, and the results are compared with many familiar reduction methods in terms of the ISE and relative ISE values pertaining to im...

Optimal least squares model approximation for large-scale linear discrete-time systems:

This research article presents a novel algorithm for the model order reduction of higher order linear time interval systems using soft computing optimization approach. In the proposed method, a new...

M. Siva Kumar

Papers

Impulse energy approximation of higher-order interval systems using Kharitonov’s polynomials:

A Novel Three Phase Multilevel Inverter with Single Dc Link For Induction Motor Drive Applications

Model reduction of linear interval systems using Kharitonov's polynomials

Optimal least squares model approximation for large-scale linear discrete-time systems:

A novel reduced order modeling of interval system using soft computing optimization approach