J. Castelló

An Adaptive Robust Predictive Current Control for Three-Phase Grid-Connected Inverters

This paper presents an adaptive robust predictive current control (RPCC) for grid-connected three-phase inverters that exhibit zero steady-state current error. The error correction is achieved by means of an adaptive strategy that works in parallel with the deadbeat algorithm, therefore preserving the typical fast response of the predictive law. The resulting control adapts to any particular L or LCL filter by estimation of the resistive part of the filter. As a variety of the RPCC class of control, it offers the best tradeoff between robustness and speed.

Wind Turbine Generation System With Optimized DC-Link Design and Control

This paper presents an optimized capacitance design for the dc link of a back-to-back converter for wind turbine power generation. The design method combines switching ripple and dynamic specifications to give the smallest possible dc-link capacitance and the required proportional-integral compensator for the voltage regulation. Furthermore, a novel concept to globally manage the on/off switching of back-to-back power subconverters, based on a finite-state machine, is presented. The proposed management system keeps control of the dc-link voltage for proper operation of both subconverters regardless of wind or grid conditions.

A New Generalized Robust Predictive Current Control for Grid-Connected Inverters Compensates Anti-Aliasing Filters Delay

In this paper, a new predictive control for grid-connected inverters is presented, which provides the best performance in terms of transient response and stability margins when analog filters in current sensing circuits are used. These filters are necessary to avoid aliasing in the A/D conversion process, which causes an important ripple on injected current into the grid and increases the total harmonic distortion. However, predictive controls are very sensitive to delays on the acquisitions, so when such anti-aliasing filters are used a reduction of stability margins is produced and the transient response is affected. The proposed predictive control allows to compensate the effect of the filter, for any order and cutoff frequency, providing the best transient response in the reference tracking and the highest stability margins. Furthermore, a modification on the adaptive strategy of current error is proposed, which allows to work with single-phase grid-connected inverters. The proposed predictive control has been tested on a 3.3-kVA single-phase grid-connected inverter with LCL filter, using different anti-aliasing filters, obtaining in all cases, better results than those offered by other predictive controls recently published.

DSP Implementation for Measuring the Loop Gain Frequency Response of Digitally Controlled Power Converters

This paper presents a method for measuring the loop gain frequency response of digitally controlled power converters, without the need of any expensive measurement equipment such as frequency response analyzers (FRA). The method is based on the traditional perturbation and measurement scheme. The perturbation is internally synthesized by the DSP and applied as pulse-width modulation to the converter. The loop input and output data are sent to a PC via universal serial bus, which performs online the DFT of sent data. The perturbation amplitude is varied with frequency to improve signal-to-noise ratio of measurements. The number of cycles used to perform discrete Fourier transform calculations is also varied to reduce the error induced by some rounding factors at high frequencies. The proposed method offers accuracy, ease of implementation, and low computational cost.

Modeling and Simulation of Non Linear Magnetic Coresat High Frequencies Using PSpice

Using PSpice of MiscroSim to simulate power converters sometimes brings awkward complications such as the simulation of real magnetic components. It deals a little bit of work to bring a good agreement between experimental and simulated results. Simulation with linear inductors or transformers does not produce good results. The reason is that real magnetic components present saturation and hysteresis, a phenomenon that characterises magnetic materials.

Obtaining the Electrical Model of a Power Transformer by Means of Finite Element Software

Abstract. The behaviour of transformers and inductors working at high-frequencies and high power density can dramatically differ from the ideal or low-frequency operation. Their performance is very dependent on the magnetic material, operating frequency and physical construction. In this paper, finite element analysis (FEA) is used to obtain an accurate characterization of the electromagnetic behaviour of these magnetic components.

Parameterizing non-linear magnetic cores for PSpice Simulation

Abstract. In this paper the main Jiles & Atherton parameters of a magnetic material, according to their particular working condition (mainly frequency, temperature and waveform) are calculated by means of a systematic procedure that use PSpice and MathCad. The modelled magnetic material is used for power electronics circuit simulation, which uses magnetic materials, working at frequencies in the region of kH, to construct transformers and inductors. Magnetic materials are the most critical components in electronics simulators due to their nonlinear behaviour and the accuracy in the simulation can only be obtained through a proper magnetic material modelling. This paper examines the modelling of the magnetic core hysteresis for high-frequency applications. As example of application, a buck converter with its inductor working near saturation is implemented and its experimental waveforms are compared with that obtained by simulation.