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

Identification of hammerstein-wiener systems including backlash input nonlinearities

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

Adaptive parameter identification of a fuel cell system for health-conscious energy management applications

Since a proton exchange membrane (PEM) fuel cell (FC) has time-varying characteristics, its online characteristics estimation (voltage, power, internal resistance, etc.) is becoming a key step in designing an energy management strategy (EMS) for hybrid FC vehicles. In this respect, this paper proposes a new method based on Lyapunov adaptation law to estimate the linear and nonlinear parameters of a renowned PEMFC model in the literature. Unlike most of similar estimators, the suggested approach determines the maximum current, which is a nonlinear parameter, online while guaranteeing the system closed-loop stability. This parameter is normally assumed to be constant while it changes through time owing to degradation and operating conditions variation. This alteration makes the model imprecise while extracting some important characteristics, such as maximum power and polarization curve. Therefore, it needs to be regularly updated along with other parameters. To demonstrate the capability of the suggested method, a detailed comparison is provided with the well-known extended Kalman filter (EKF) as an attested nonlinear estimator. Moreover, to highlight the effectiveness of the nonlinearity consideration, a comparison with KF is performed where the nonlinear parameter is considered constant. The performed experiments on a 500-W PEMFC show that the proposed method can be over twice as accurate as EKF and KF concerning the estimation of maximum power and current while its runtime is nearly half of them

The KATRIN Pre-Spectrometer at reduced Filter Energy

The KArlsruhe TRItium Neutrino experiment, KATRIN, will determine the mass of the electron neutrino with a sensitivity of 0.2 eV (90% C.L.) via a measurement of the beta-spectrum of gaseous tritium near its endpoint of E_0 =18.57 keV. An ultra-low background of about b = 10 mHz is among the requirements to reach this sensitivity. In the KATRIN main beam-line two spectrometers of MAC-E filter type are used in a tandem configuration. This setup, however, produces a Penning trap which could lead to increased background. We have performed test measurements showing that the filter energy of the pre-spectrometer can be reduced by several keV in order to diminish this trap. These measurements were analyzed with the help of a complex computer simulation, modeling multiple electron reflections both from the detector and the photoelectric electron source used in our test setup.Comment: 22 pages, 12 figure