Frequency identification of Wiener systems with Backlash operators using separable least squares estimators

This paper deals with the identification of Wiener models that involve backlash operators bordered by possibly noninvertible parametric lines. The latter are also allowed to cross each other making possible to account for general-shape static nonlinearities. The linear dynamic subsystem is not-necessarily parametric but is BIBO stable. A frequency identification method is developed that provides estimates of the nonlinear operator parameters as well as estimates of the linear subsystem frequency gain. The method involves standard and separable least squares estimators that all are shown to be consistent. Backlash operators and memoryless nonlinearities are handled within a unified framework.Preprin

Nonlinear control design and averaging analysis of a full-bridge boost rectifier

We are considering the problem of controlling AC/DC full bridge converters. The control objectives are twofold:(i) guaranteeing a regulated voltage for the supplied load, (ii) enforcing power factor correction (PFC) with respect to the main supply network. The considered problem is dealt with using a nonlinear controller that involves two loops in cascade. The inner-loop is designed, using sliding mode approach, to cope with the PFC issue. The outer-loop is designed to regulate the converter output voltage. While several double-loop regulators (designed for different converters) can be found in the relevant literature, it is the first time that a so formal average analysis is developed that rigorously describes the controller performances. The development of such theoretical analysis framework is a major motivation of this paper.Postprint (published version

Nonlinear control of single-phase shunt active power filter. Theoretical analysis of closed-loop performances.

The problem of controlling single-phase shunt active power filter is addressed in presence of nonlinear loads. The control objective is twofold: (i) compensation of harmonic and reactive currents absorbed by the nonlinear load; (ii) regulation of the inverter output capacitor voltage. A two-loop cascade control strategy is developed that includes an inner-loop designed, using the backstepping technique, to cope with the compensation issue and an outer-loop designed to regulate the capacitor voltage. The controller performances are formally analysed, using the averaging theory. The analysis results are illustrated by simulation.Preprin

Advanced nonlinear control of three phase series active power filter

The problem of controlling three-phase series active power filter (TPSAPF) is addressed in this paper in presence of the perturbations in the voltages of the electrical supply network. The control objective of the TPSAPF is twofold: (i) compensation of all voltage perturbations (voltage harmonics, voltage unbalance and voltage sags), (ii) regulation of the DC bus voltage of the inverter. A controller formed by two nonlinear regulators is designed, using the Backstepping technique, to provide the above compensation. The regulation of the DC bus voltage of the inverter is ensured by the use of a diode bridge rectifier which its output is in parallel with the DC bus capacitor. The Analysis of controller performances is illustrated by numerical simulation in Matlab/Simulink environment

Frequency identification of Wiener systems with Backlash operators using separable least squares estimators

This paper deals with the identification of Wiener models that involve backlash operators bordered by possibly noninvertible parametric lines. The latter are also allowed to cross each other making possible to account for general-shape static nonlinearities. The linear dynamic subsystem is not-necessarily parametric but is BIBO stable. A frequency identification method is developed that provides estimates of the nonlinear operator parameters as well as estimates of the linear subsystem frequency gain. The method involves standard and separable least squares estimators that all are shown to be consistent. Backlash operators and memoryless nonlinearities are handled within a unified framework

Adaptive nonlinear control of single-phase to three-phase UPS system

This work deals with the problems of uninterruptible power supplies (UPS) based on the single-phase to three-phase converters built in two stages: an input bridge rectifier and an output three phase inverter. The two blocks are joined by a continuous intermediate bus. The objective of control is threefold: i) power factor correction “PFC”, ii) generating a symmetrical three-phase system at the output even if the load is unknown, iii) regulating the DC bus voltage. The synthesis of controllers has been reached by two nonlinear techniques that are the sliding mode and adaptive backstepping control. The performances of regulators have been validated by numerical simulation in MATLAB / SIMULINK

Nonlinear control design and averaging analysis of a full-bridge boost rectifier

We are considering the problem of controlling AC/DC full bridge converters. The control objectives are twofold:(i) guaranteeing a regulated voltage for the supplied load, (ii) enforcing power factor correction (PFC) with respect to the main supply network. The considered problem is dealt with using a nonlinear controller that involves two loops in cascade. The inner-loop is designed, using sliding mode approach, to cope with the PFC issue. The outer-loop is designed to regulate the converter output voltage. While several double-loop regulators (designed for different converters) can be found in the relevant literature, it is the first time that a so formal average analysis is developed that rigorously describes the controller performances. The development of such theoretical analysis framework is a major motivation of this paper

A Novel Observer Design for Sensorless Sampled Output Measurement: Application of Variable Speed Doubly Fed Induction Generator

International audienceThis paper presents a novel exponentially convergent nonlinear observer design for variable speed doubly fed induction generators (DFIG). The main feature of the proposed observer lies in the use of sampled-data without necessitating mechanical sensors, making the observer more reliable. A main component of the observer is an inter-sampled predictor of the output current vector. The observer exponential convergence is established and analyzed using Lyapunov stability technique and the small gain theorem. The proposed observer combines the advantage of a high-gain structure in terms of convergence speed and the continuity of the estimated state trajectory. One difficulty of the present observer design problem is that the electromagnetic torque is not related to the output by an injective map. The simulation results in variable speed DFIG operation are provided to confirm the theoretical results

Nonlinear control of single-phase shunt active power filter. Theoretical analysis of closed-loop performances.

The problem of controlling single-phase shunt active power filter is addressed in presence of nonlinear loads. The control objective is twofold: (i) compensation of harmonic and reactive currents absorbed by the nonlinear load; (ii) regulation of the inverter output capacitor voltage. A two-loop cascade control strategy is developed that includes an inner-loop designed, using the backstepping technique, to cope with the compensation issue and an outer-loop designed to regulate the capacitor voltage. The controller performances are formally analysed, using the averaging theory. The analysis results are illustrated by simulation