Search results for "Converter"
showing 10 items of 275 documents
Linear-non-linear digital control for dc/dc converters with fast transient response
2009
A linear-non-linear digital control for multi-module DC/DC converters that improves system stability, solves the limit-cycle problem, reduces recovery time and limits over- and under-shoots in regulated output voltage, is presented. A simulation model in Matlab-Simulink/Active-HDL mixed environment is described. Preliminary hardware tests on a single-phase step-down converter are reported. Simulation and experimental results are shown.
Identification and Robust Control of a Quadratic DC/DC Boost Converter by Hammerstein Model
2015
This paper deals with the theoretical framework definition and the experimental application of the Hammerstein (HM) identification and related robust control technique to a quadratic dc/dc single-switch boost (Q-boost) converter. A set of fourth-order transfer functions (TFs) has been identified with the Hammerstein approach, on the basis of a pseudorandom-binary-sequence (PRBS) excitation signal. The set of identified TFs has been then used to design a suitable robust control technique, able to properly deal with the converter parameter uncertainty and load variations. The proposed approach has been tested in numerical simulation and validated experimentally on a suitably developed test se…
Difference temperature-to-time electronic interface based on a thermistor-to-generalized impedance converter
2010
Abstract In this work a difference temperature-to-time converter is shown using two thermistors working in a DC generalized impedance converter. Voltage drop in one of the thermistors depends on the temperature difference between them. This voltage is compared with a time varying exponential reference voltage obtaining a time interval at the output circuit with good linear dependence with respect to the input temperature difference. Experimental results are obtained showing a new generalized impedance converter application. The implemented circuit was characterized by a repeatability of 1.0%, a reproducibility of 4.5% and a relative accuracy of 1.3%.
High-Efficiency Regulation Method for a Zero-Current and Zero-Voltage Current-Fed Push–Pull Converter
2011
A new high-efficiency regulation method for a zero-current and zero-voltage current-fed push-pull converter is presented. The method proposed is based on the use of a controlled transformer as a post-regulator, which adds or subtracts an additional voltage to the output filter of the converter. An auxiliary regulator, which only handles a percentage of the output power, controls this transformer, and therefore, results in much higher efficiency than a normal preregulator would have. The novelty of the presented converter is that regulation is achieved without affecting the zero-voltage and zero-current switching in any working conditions. Small- and large-signal models of the converter have…
Dynamic modelling of a quadratic DC/DC single-switch boost converter
2017
This manuscript proposes the analysis of a Quadratic Boost Converter (QBC) transformer-less single switch typology. The state space average dynamic model and a constrained state space average model taking into account the mono-directional components of the converter (diodes, switches) have been analyzed. The static gain expression taking into consideration the parasitic elements of the converter and the small-signal transfer function of the QBC typology under study has been obtained. A sensitivity analysis has shown a high variation of the gain versus duty-cycle and of the derivative gain versus parasitic parameters of the converter in the range of the duty-cycle from 0.6 to 0.8 which is ra…
DC/DC converter topologies for electrolyzers: State-of-the-art and remaining key issues.
2017
In recent years, the use of electrolyzers to produce cleanly and efficiently hydrogen from renewable energy sources (i.e. wind turbines, photovoltaic) has taken advantage of a growing interest from researchers and industrial. Similarly to fuel cells, DC/DC converters are needed to interface the DC bus with the electrolyzer. Usually, electrolyzers require a low DC voltage to produce hydrogen from water. For this reason, a DC/DC buck converter is generally used for this purpose. However, other DC/DC converter topologies can be used depending on the feature of the electrolyzer and electrical grid as well. The main purpose of this paper is to present the current state-of-the-art of DC/DC conver…
DSP Implementation for Measuring the Loop Gain Frequency Response of Digitally Controlled Power Converters
2012
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 calculation…
Four-Level Three-Phase Inverter With Reduced Component Count for Low and Medium Voltage Applications
2021
This paper proposes a novel three-phase topology with a reduced component count for low- and medium-voltage systems. It requires three bidirectional switches and twelve unidirectional switches for producing four-level voltages without using flying capacitors or clamping diodes, reducing the size, cost, and losses. Removing flying capacitors and clamping diodes allows it to simplify control algorithms and increase the reliability, efficiency, and lifetime. A modified low-frequency modulation (LFM) scheme is developed and implemented on the proposed topology to produce a staircase voltage with four steps. Further, a level-shifted pulse width modulation (LSPWM) is used to reduce the filter siz…
Sliding Mode Control of Quadratic Boost Converters Based on Min-Type Control Strategy
2023
The paper deals with the control of a quadratic boost converter supplied by low-voltage energy sources, such as photovoltaic panels, fuel cells, or batteries. The control scheme consists of two control loops. A min-type controller governs the inner loop to force the current state of the nominal model to converge in a neighborhood of the equilibrium state. The external loop processes the output tracking error using an integrator, and it allows reconfiguring the converter's working point by changing the equilibrium state given in the input to the internal loop. This configuration assures both zero tracking error of the output voltage and robustness against load and input voltage variations an…
GRID STABILITY IMPROVEMENT BY RES-BASED GENERATORS AND BATTERY ENERGY STORAGE SYSTEMS IN SMALL ISLANDS
2021
The integration of Renewable Energy Sources (RES) with power electronics interface to the grid, without the back-up of rotating inertia, endangers frequency stability. This issue becomes particularly critical in isolated power systems, like those of small islands not supplied by the main grid, in the case of high shares of production from unpredictable renewables such as photovoltaic and wind sources. Consequently, to preserve the security and the reliability of these systems, it is necessary to adopt new frequency adjustments mechanisms. In this context, the thesis investigates the transition toward an economically and technically feasible generating system based on RES, to achieve specifi…