Search results for "converter"

Dynamic performance evaluation of a non linear digital control technique for multiphase VRMs

2010

A Novel Symmetrical Boost Modulation Method for qZS-based CHB Inverters

2020

Quasi-Z-source cascaded H-bridge (qZS-CHB) inverters are arising as an innovation in the field of the electrical conversion for PV applications. This type of converters inherit the advantages of multilevel inverters and single-stage configuration. In this context, this paper proposes a novel symmetrical boost modulation strategy for qZS CHB multilevel inverters to increase the performance in terms of voltage stresses and power quality. The novelty lies in the adoption of a different concept to generate the shoot-through states compared to the traditional methods. Simulation analysis in a grid connected application to evaluate the benefits of this boost method is performed in the MATLAB/PLEC…

Power losses comparison between Silicon Carbide and Silicon devices for an isolated DC-DC converter

2021

In recent years, new efficient power devices have been implemented. Silicon Carbide has replaced silicon as regards the production and the utilization of many devices, such as MOSFETs, diodes, IGBTs and many others. SiC devices are characterized by a low reverse recovery charge, high carrier saturation velocity, by which it is possible to work at high frequency, and high breakdown voltage. Thanks to the great thermal conductivity and the wide bandgap, these devices can operate at high temperature and reach high voltages and currents. What is important to stress is the fact that power losses in SiC devices are lower than the silicon ones. These are the reasons why these devices are utilized …

A New Device for the Control and the Connection to the Grid of Combined RES-based Generators and Electric Storage Systems

2013

In this paper a new device for the control and the connection to the supply utility grid of combined RES-based generators and electric storage systems is presented. The device is a bidirectional converter that can be controlled so as to facilitate the interface between the low voltage grid and photovoltaic or wind generators combined with batteries, contemporary addressing the requirements of the reference technical standards for users connection and providing different ancillary services. In the paper the functioning of the device and its circuit diagram are described, the single parts are shown and the potentiality of its control system are commented. © 2013 IEEE.

Estimation of power supply harmonic impedance using a controlled voltage disturbance

2002

A novel method for power system impedance estimation is presented. The method employs a power converter to inject a voltage transient onto the supply system. The impedance is estimated through correlation of the measured voltage and current transients. Simulations and experimental results demonstrate the effectiveness of this measurement technique.

Power Maximization of a PV-Wind HRES via DC-link Voltage Boosting

2009

This paper describes a method for the optimization of a Hybrid Renewable Energy System applied to a low power Photovoltaic-Wind plant. This approach exploits the DC link with a voltage higher than the correspondent value of the batteries, thanks to a suitable DC/DC converter. The goodness of the methodology is firstly proved by means of a novel graphical technique and then verified through numerical simulations. The results are discussed and show that, adopting the proposed technique, a significant increase of the generated power and of the annual energy produced can be achieved.

On the design of observers robust to load variations for synchronous converters

2015

Due to the ever growing concern on energy efficiency issues, synchronous rectification gained increasing attention in recent years. In the semiconductor industry fast controllers developed for DC-DC converters are typically based on inductor current measures. In this context system costs and performances strictly depend on the current sensor and its proper design. In this paper we present a sensorless synchronous approach based on a current observer. The same observer formulation is valid for the three standard DC-DC converters, simplifying its design for different configurations. Furthermore the designed observers are proven to be robust against load variations, the most uncertain paramete…

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…

New approach for harmonic mitigation in single-phase five-level CHBMI with fundamental frequency switching

2017

The main objective of this paper is to study and analyse the voltage output waveform of a multilevel inverter, to suggest a new approach for harmonic mitigation improving the converter performance. These last type of converters represent a new technology in the field of DC/AC electrical energy conversion, presenting advantages respect to the traditional converters. In fact, the multilevel power converters present a low harmonic content and a high voltage level. The paper considers a five-level single-phase cascaded H-bridge inverter and fundamental frequency modulation techniques. The voltage waveform analysis has allowed to identify a working area of the converter where there are lowest va…

Robust current observer design for DC-DC converters

2014

In recent years several fast response controllers have been proposed for DC-DC converters. The majority of them rely on a cascade control structure involving the inductor's current in the control function as its faster dynamics, respect to output voltage, allows a significant increase in the regulation performance; the drawback is the need of a proper and expensive current sensor. In this paper a simple and robust formulation for the design of a current observer, based on the output voltage measurement is presented. The formulation is common for the three standard DC-DC converters and the resulting observer is robust to load variation. The observers have been tested in a cascade PI control …