Search results for "Hammerstein model"

Nonlinear Modeling of DC/DC Converters Using the Hammerstein's Approach

2007

This paper deals with the modelling of highly nonlinear switching power-electronics converters using black-box identification methods. The duty cycle and the output voltage are chosen, respectively, as the input and the output of the model. A nonlinear Hammerstein-type mathematical model, consisting of a static nonlinearity and a linear time-invariant model, is considered in order to cope with the well-known limitations of the more common small-signal models, i.e. the entity of the variations of the variables around a well-defined steady-state operating point and the incorrect reproduction of the steady-state behavior corresponding to input step variations from the above steady-state operat…

Robust control of a Hammerstein model of DC/DC converters

2007

This paper deals with the robust control of a Hammerstein mathematical model of DC/DC converters, consisting of the nonlinear static characteristics of the converter followed by one of a few number of linear time- invariant models which describe the converter in the useful working range. One of these models is assumed as the nominal model of the system and the remaining models are used for describing the model uncertainty. Nominal behaviour is assured using H-2 optimal control method, Robust stability and behaviour are assured by imposing H-infin specifications. The closed loop control system consisting of the converter Hammerstein model and the robust controller is analyzed by means of sim…

Identification of Nonlinear Systems Described by Hammerstein Models

2004

This paper deals with a method for identification of nonlinear systems suitable to be described by Hammerstein models consisting of a static nonlinearity followed by an ARX linear model. The estimation of the static nonlinearity is carried out supplying the system with a sequence of step signals of various amplitude and determining the corresponding steady-state responses. The estimation of the parameters of the ARX linear system is carried out by means of a least square estimator using data generated supplying the system with a Pseudorandom Binary Sequence (PRBS). The method in question is able to identify static nonlinearities of general type, also with hysteresis and/or discontinuities. …

Identification of a Hammerstein model for DC/DC converters operating in CCM

2005

This paper deals with a method for identification of a Hammerstein model of DC-DC converters operating in continuous conduction mode (CCM). This model has the duty cycle and the output voltage as input and output, respectively; it consists of a static nonlinearity and a linear and time-invariant model. The aim of the modeling the system by means of a Hammerstein model is due to its capability of describing the converter in a range of steady-state operating points instead of a desired well defined operating point as occurs for the small-signal models which are the more common mathematical description to approach the study of the converters themselves. The nonlinear characteristic of the Hamm…

Hammerstein Model-Based Robust Control of DC/DC Converters

2007

This paper deals with model-based robust control of DC/DC power electronic converters. The converter is modelled by means of its static characteristic and a few continuous-time linear and time-invariant (LTI) models corresponding to contiguous ranges of duty-cycle. The model appears as a Hammerstein model in which the values of the parameters of the LTI part depend on the actual duty-cycle operating range. This suggests to describe the converter as an uncertain system to be controlled using robust control techniques. Frequency domain approach is used for describing the nominal model and the uncertainty. In view of applying robust control, identification of the LTI models is performed by mea…

Identification and robust control of DC/DC converter Hammerstein model

2008

Abstract—This paper deals with model-based robust control of dc/dc power electronic converters. The converter is described by means of a Hammerstein model consisting of the nonlinear static characteristics of the converter and a linear time-invariant (LTI) uncertainmodel whose parameters depend on the actual duty-cycle operating range. This suggests that the controller be designed using robust control techniques. In view of applying robust control, identification of the earlier LTI models is performed by means of simulation experiments, carried out on a converter switching model implemented onMATLAB/SIMULINK environment. Internal model control (IMC) structure is employed for the controller …

Robust and Model Predictive Control applied to DC/DC converters and Shunt Active Filters

Al giorno d'oggi, la domanda di energia elettrica incrementa giorno per giorno. La gente spesso la usa con superficialità sottovalutando quanto essa sia preziosa. Fino a qualche decennio fa, la generazione di energia elettrica era centralizzata e dipendeva dallo sfruttamento delle risorse fossili. La limitatezza delle fonti fossili, insieme agli effetti ambientali del loro sfruttamento, hanno portato la ricerca a trovare vettori energetici alternativi poco inquinanti e facilmente reperibili. Lo sviluppo e la diffusione delle fonti energetiche rinnovabili hanno sancito la fine di una rete elettrica centralizzata a favore di una nuova idea di rete elettrica di tipo distribuita che permette di…