Search results for "Converters"
showing 10 items of 140 documents
A novel digital control for DC/DC converters to improve steady-state performances
2006
This paper describes an innovative digital PWM control implementation for low voltage, high current DC-DC converters. The proposed technique, based on the use of a low resolution DAC, improves steady-state performances, minimizing limit cycle effects. The novel technique is tested on a FPGA-based single phase buck converter operating at 250 kHz. A detailed description of the proposed architecture is given and test results, simulation and experimental ones, are shown
Hybrid Modelling and Control of a Class of Power Converters With Triangular-Carrier PWM Inputs
2021
In this paper, a new control design procedure for a class of power converters based on hybrid dynamical systems theory is presented. The continuous-time dynamics, as voltage and current signals, and discretetime dynamics, as the on-off state of the switches, are captured with a hybrid model. This model avoids the use of averaged and approximated models and includes the PWM as well as the sample-and-hold mechanism, commonly used in the industry. Then, another simplified hybrid system, whose trajectories match with the original one, is selected to design the controller and to analyse stability properties. Finally, an estimation of the chattering in steady state of the voltage and current sign…
Assessment of MOSFET switching losses in an LLC converter by a calorimetric method
2023
The present work aims to implement a calorimetric method to measure the power dissipated during MOSFET switching in a high efficiency LLC resonant converter. The power dissipated from switching can significantly impact the total power dissipated by the device and consequent efficiency, so correct quantification is fundamental for optimizing the devices and increasing the efficiency of the converters. In LLC converters, this type of dissipated power cannot be measured with standard methods such as measurement with oscilloscopes as some of the energy that is recovered and not dissipated. The calorimetric method requires reasonably accurate measurement of thermal resistance and the temperature…
An original control strategy of storage systems for the frequency stability of autonomous grids with renewable power generation
2021
This work examines the operation of the autonomous power system of a geographical island assuming the integration of significant generation shares from renewable energy sources and the installation of the required storage systems. The frequency stability of the system is investigated considering different operating conditions, in terms of load demand and renewable power generation. The main focus of the work is an original control strategy specifically designed for power converters interfacing storage units to the grid. The proposed strategy is based on an extended frequency droop control, which selects specific droop settings depending on the operating mode—charge or discharge—of the stora…
Non-Linear Inductors Characterization in Real Operating Conditions for Power Density Optimization in SMPS
2021
The exploitation of power inductors outside their linear region in switching converters can be achieved by raising the current until a decreasing of the inductance can be noticed. It allows using a smaller magnetic core increasing the power density of the converter. On the other hand, a detailed description of the magnetization curve including the temperature is required. Since this information is often not included in the inductor’s datasheets, this paper shows how to identify the behavior of an inductor when it is operated up to saturation and its temperature rises. In order to characterize the inductor in real operating conditions, a dedicated measurement rig has been developed. It consi…
Comprehensive Modeling and Experimental Testing of Fault Detection and Management of a Nonredundant Fault-Tolerant VSI
2015
This paper presents an investigation and a comprehensive analysis on fault operations in a conventional three-phase voltage source inverter. After an introductory section dealing with power converter reliability and fault analysis issues in power electronics, a generalized switching function accounting for both healthy and faulty conditions and an easy and feasible method to embed fault diagnosis and reconfiguration within the control algorithm are introduced. The proposed system has simple and compact implementation. Experimental results operating both at open- and closed-loop current control, obtained using a test bench realized using a dSPACE system and the fault-tolerant inverter protot…
Interior Permanent Magnet Synchronous Machine Drive Powered by Fuel Cell for Automotive Applications
2020
Electric vehicles represent an optimal solution for the reduction of pollution in urban areas. In particular, the Fuel Cell (FC) technology is a promising solution especially for its charging times and zero CO2 direct emissions. The paper addresses the design and performance study of an Interior Permanent Magnet Synchronous Machine (IPMSM) drive powered by fuel cell for automotive applications. The IPMSM drive is powered by the use of 5,5 kW FC unit and it is composed of two DC-DC power converters and one inverter. In detail, a test bench has been carried out for the evaluation of the performances of each IPMSM drive conversion stage. Moreover, in order to simulate automotive working condit…
Control of ultra-high switching frequency power converters using virtual flux-based direct power control
2017
This paper presents a control technique for ultra-high switching frequency rectifiers known as virtual flux-based direct power control (VF-DPC). This method utilizes AC voltage sensors to provide better power quality at the input and output of power converters. Performance of an ultra-high switching frequency converter using the extended and conventional VF-DPC method is analyzed. The analysis has shown that the extended VF-DPC method can reduce better the total harmonic distortion (THD) of input currents and the ripples of the output DC voltage as compared to conventional VF-DPC. Finally, the effect of switching frequency and inductance size on rectifier operation is investigated in this s…
Improved Switching Strategy for Selective Harmonic Elimination in DC-AC Signal Generation via Pulse-Width Modulation
2013
Published version of an article in the journal: Abstract and Applied Analysis. Also available from the publisher at: http://dx.doi.org/10.1155/2013/870904 Open Access We present an advanced design methodology for pulse-width-modulated (PWM) DC-AC signal generation. Using design methods based on the Walsh transform, AC sinusoidal signals can be approximated by suitable PWM signals. For different AC amplitudes, the switching instants of the PWM signals can be efficiently computed by using appropriate systems of explicit linear equations. However, the equation systems provided by conventional implementations of this approach are typically only valid for a restricted interval of AC amplitudes a…
Power Conversion System for Improved Linear Generator in sea wave energy harvesting applications
2020
Nowadays, many islands worldwide are lack of electrical energy. Thus, it is convenient to exploit available renewable energy sources, among which sea waves near the islands. This paper focuses on the power conversion system coupled with an offshore wave energy device, such as an improved linear generator, to be used for sea wave energy harvesting. Particularly, the design of the linear generator has been proposed to improve the energy efficiency of the entire system. The proposed power conversion system is composed by two Boost Rectifier (BR) directly coupled to the linear generator, and one Voltage Source Inverter (VSI), which it is used as front-end between the DC-bus and the grid. The pr…