Search results

Conventional isolated dc–dc converters offer an efficient solution for performing voltage conversion with a large improved voltage gain. However, the small-signal analysis of these converters shows that a right-half-plane (RHP) zero appears in their control-to-output transfer function, exhibiting a nonminimum-phase stability. This RHP zero can limit the frequency response and dynamic specifications of the converters; therefore, the output voltage response is sluggish. To overcome these problems, the purpose of this study is to analyze, model and design a new isolated forward single-ended primary-inductor converter (IFSEPIC) through RHP zero alleviation.

At first, the normal operation of the suggested IFSEPIC is studied. Then, its average model and control-to-output transfer function are derived. Based on the obtained model and Routh–Hurwitz criterion, the components are suitably designed for the proposed IFSEPIC, such that the derived dynamic model can eliminate the RHP zero.

The advantages of the proposed IFSEPIC can be summarized as: This converter can provide conditions to achieve fast dynamic behavior and minimum-phase stability, owing to the RHP zero cancellation; with respect to conventional isolated converters, a larger gain can be realized using the proposed topology; thus, it is possible to attain a smaller operating duty cycle; for conventional isolated converters, transformer core saturation is a major concern, owing to a large magnetizing current. However, the average value of the magnetizing current becomes zero for the proposed IFSEPIC, thereby avoiding core saturation, particularly at high frequencies; and the input current of the proposed converter is continuous, reducing input current ripple.

The key benefits of the proposed IFSEPIC are shown via comparisons. To validate the design method and theoretical findings, a practical implementation is presented.

At first, the organic/inorganic and hybrid PV materials by their electrical model are described. Then the proposed converter topology, circuit analysis and various operating modes of converter according to on/off timing of switches are investigated. The current and voltage in the converter components are illustrated and the voltage gain and switching stress of proposed converter are presented. Finally, to show the effectiveness of the proposed converter, the power loss analysis is provided and the simulation is done in PSIM software. In the last section, the advantages of the proposed topology of higher efficiency by lower number of components in compare with other conventional topologies are presented.

In this paper, an improved topology of DC-DC converter based on VL technique is proposed for Perovskite Solar cells (PeSCs). The PeSCs attracted a lot of interest due to their potential in combining the advantages of both organic and inorganic components. The proposed converter by using fewer components and higher output voltage generation in compare with conventional ones could be a good candidate for PeSCs due to lower efficiency of this cells. The performance of converter is expressed in continuous conduction mode (CCM) and discontinuous conduction mode (DCM), and the boundary conditions for the proposed converter is presented.

By using VL technique, this converter is used to boost the lower output voltage levels of PeSCs for grid connection. The PV cell output voltage is increased from 24.5 V to 106 V by proposed converter topology. The step-by-step voltage increasing by charging and discharging of inductor and capacitor is used for boosting the input voltage. By comparing other converters, there is no design complexity in the proposed converter structure, and the power loss is much reduced which increases the converter efficiency. On the other hand, due to using lower number of elements of energy storage elements such as inductors and capacitors, the converter cost is also diminished. Therefore, the design topology simplicity which result simple control algorithm and lower number of components which diminish the system cost by appropriate voltage boosting capability are the main advantages of this proposed topology for new PeSCs which don’t have enough efficiency in compare with old Si PV cells.

In this paper, by using the lower number of components a new structure of DC-DC converter based on the VL technique is proposed. The advantages of this converter such as the simplicity, easier control and high voltage gain by lower power loss, could make this converter a good candidate for new PeSCs where the system whole efficiency will be a critical point to have the unique properties of this new materials in lower loss.

The purpose of this paper is to describe a two‐level hierarchical control strategy for electrical energy transfers in multisource renewable energy systems. The aim of the control design is to perform the energy transfers, according to the sources power variations and the load characteristics.

The controller determines the operating mode of the multisource renewable energy system and the power ratio provided by each source to satisfy the load demand. The study is based on an accurate model of the DC/DC converters coupled on the DC bus. The performance of the controller is compared with the usual method based on the measurements of the system variables with sensors (solar radiation, shaft speed, voltages, and currents).

The proposed method does not need extra sensors to measure the available power for each source.

The method is developed for an hybrid system with two sources (photovoltaic and lead‐acid battery bank) and specific zero voltage switch full‐bridge isolated buck DC/DC power converters but can easily extended to more sources and other classes of DC/DC converters.

The method is assessed through computer simulations using a simple comprehensive model. An experimental device is also developed by the GREAH Research Group of University Le Havre (France). The GREAH also participates to a technologic centre with similar topology on the site of Fecamp (France).

The proposed autonomous control schema is suitable to control hybrid systems with several energy sources in remote areas.

The main contributions of this work are first to introduce a two stages controller and second to use the duty cycle value of the power converters as decision criteria to switch off/on the sources.

This paper presents a computer‐aided design (CAD) tool for the design of isolated dc‐dc converters.

This tool, developed in Matlab environment, is based on multiobjective optimization (MO) using genetic algorithms. The Elitist Nondominated Sorting Genetic Algorithm is used to perform search and optimization whereas analytical models are used to model the power converters. The design problem requires minimizing the weight, losses and cost of the converter while ensuring the satisfaction of a number of constraints. The optimization variables are, as for them, the operating frequency, the current density, the maximum flux density, the transformer dimensions, the wire diameter, the core material, the conductor material, the converter topology (among Flyback, Forward, Push‐Pull, half‐bridge and full‐bridge topologies), the number of semiconductor devices associated in parallel, the number of cells associated in series or parallel as well as the kinds of input and output connections (serial or parallel) of these cells. Finally, the design of an auxiliary railway power supply is presented and discussed.

The results show that such tool to design dc‐dc power converters presents several advantages. In particular, it proposes to the designer a set of solutions – instead of a single one – so that he can choose a posteriori which solution best fits the application under consideration. Moreover, interesting solutions not considered a priori can be found with this tool.

To the best of the authors’ knowledge, such a CAD tool including a MO procedure taking several topologies into account has not been suggested so far.

This study aims to propose a new non-isolated Multi-Input Zeta-SEPIC (MIZS) dc–dc converter for renewable energy sources integration with different voltage levels (low-voltage source, high-voltage source). The chosen configuration of the converter is capable of performing bucking as well as boosting operations in various modes of operation.

Parameters of the selected MIZS converter are designed using the time-domain analysis. The selected converter belongs to the sixth-order family with two switches and six energy storage elements. State-space model of the converter is developed for each mode of operation, and using these individual state-space models, an average state-space model of the converter useful to carry out detailed analysis for different operating conditions is developed. Analysis related to operational stability of the converter is also carried out using Participation Factor (PaF)-based Eigen value analysis.

Using the PaF-based Eigen analysis, participation of the various state variables in different Eigen modes and vice versa is carried out. Performance of the converter for different parameter variations in the allowable range is determined and the same has been used to find the operational stability of the converter under different modes of operation. The selected converter has low inductor ripple currents and output voltage ripples when delivering the power to load.

Because operational stability of the converter under various operating conditions is one of the key performance indicators for selecting a particular type of converter, PaF-based Eigen value analysis has been carried out using the average state-space model developed for the selected MIZS converter. Operational stability analysis of the converter is carried out for parameter variations also. In addition, participation of the various states in each Eigen mode and vice versa have been analyzed for designed parameter values and also variation within the specified range of variations.

This paper aims to propose Hidden Converter (H-Converter) combined with dual port 3Ø inverter for energy storage application to produce wide range of voltage. Some of the application required wide range of voltages, but problem from E-chopper is either boost or buck mode of operations, both modes are not possible. To overcome this drawback, H-Converter is combined with dual port 3Ø inverter controlled by carrier-based pulse width modulation (CB-PWM) technique is added with zero sequence injection.

Hidden converter is a bidirectional DC-DC chopper used to convert fixed DC to variable DC and vice versa in both buck and boost modes of operations. Dual port inverter is combined with hidden DC-DC converter can produce wide range of voltages.

The bidirectional DC-AC converter requires less power for processing and consumes less power losses by using modest carrier built- pulse width modulation scheme through proposed zero structure addition.

By using this proposed strategy H-Converter can produce wide range of voltage in both the sides and mostly power is processed in the 3Ø inverter with a one stage conversion with less power loss. As a result, with one stage power conversion has more efficiency because of less power loss. This proposed converter has designed by analysis, and the real time result is tested in an experiment.

The paper presents the findings of an R&D project connected to the development of 50 kW auxiliary power supply for the high‐voltage DC‐fed commuter trains. The aim was to introduce a new generation power converter utilizing high‐voltage insulated gate bibolar transistor (IGBT) modules, which can outpace the predecessors in terms of efficiency and power density, i.e. to provide more power for smaller volumetric space.

For development of the proposed converter, mathematical analysis and computer simulations were used. The software intended for simulations is Ansoft Simplorer, which is a mixed‐technology simulator for electrical, electromechanical, power electronic systems and drive applications. For the verification of theoretical results the full‐scale laboratory prototype of the proposed converter was developed and tested.

Thanks to increased switching frequency and current‐doubler rectifier (CDR) implemented in the proposed converter, the power dissipation of the isolation transformer was reduced by 30 percent as compared to earlier designs. Moreover, the 27 and 24 percent reductions in rectifier and inductor losses, respectively, led to approximately 1 percent efficiency rise of the proposed converter in comparison with its predecessors. Also, the proposed three‐level topology outpaces the two‐level one by more than 20 percent in terms of power density.

The proposed converter topology is aimed for the high‐voltage DC trains. With small modifications it also can be used in trams, trolleybuses as well as in some industrial applications.

The paper presents the novel DC/DC converter topology with 3.3 kV IGBT‐based three‐level neutral point clamped inverter, high‐frequency isolation transformer and the CDR.

This study aims to extend the driving range by on-board charging with use of photovoltaic (PV) source, avoiding the dependency on the grid supply and energy storage system in addition to that reduce the conversion complexity influenced on converter section of electric vehicle (EV) system.

This paper proposed a PV fed integrated converter topology called integrated single-input multi-output (I-SIMO) converter with enriched error tolerant fuzzy logic controller (EET-FLC) based control technique to regulate the speed of brushless direct current motor drive. I-SIMO converter provides both direct current (DC) and alternating current (AC) outputs from a single DC input source depending on the operation mode. It comprises two modes of operation, act as DC–DC converter in vehicle standby mode and DC–AC converter in vehicles driving mode.

The use of PV panels in the vehicle helps to reduce dependence of grid supply as well as vehicle’s batteries. The proposed topology has to remove the multiple power conversion stages in EV system, reduce components count and provide dual outputs for enhancement of performance of EV system.

The proposed topology leads to reduction of switching losses and stresses across the components of the converter and provides reduction in system complexity and overall expenditure. So, it enhances the converter reliability and also improves the efficiency. The converter provides ripple-free output voltage under dynamic load condition. The performance of EET-FLC is studied by taking various performance measures such as rise time, peak time, settling time and peak overshoot and compared with conventional control designs.

The purpose of this paper is to derive the small-signal/canonical model derivation of the high-side active clamp forward converter (ACFC) with diode rectification for ideal and with resistive parasitics. It also covers the analysis of ACFC small-signal model with resistive parasitics using computer-aided modeling software Personal Computer Simulation Program with Integrated Circuit Emphasis (PSPICE) 16.6. The effects of variation of system parameters on the ACFC’s state transfer functions and operations have been highlighted in this paper.

The large-signal model and small-signal model of the ACFC with diode rectification has been derived using AC small-signal modeling approach.

The operating point of the converter changes with the consideration of resistive parasitics compared with the ideal case. The response obtained from the hardware matches with the time domain response of the averaged model and switch model developed in PSPICE.

This paper limits the study of ACFC small-signal behavior by using computer-aided design software PSPICE. The dead time of the converter is not considered because it is negligible when compared with the on and off time. The leakage inductance which plays a role in zero voltage switching of the ACFC switches is neglected in the analysis as it is very small compared to the magnetizing inductance. The switching losses are not considered in the modeling.

The mathematical computation of deriving the system transfer functions from canonical model is complex and time consuming.

The modeling with resistive parasitics improves the effectiveness of the equivalent model. Also, the analysis with computer-aided modeling software PSPICE gives reliable results in less time.

Because of the logic delay in the converter, the minimum turn on time of the switch is influenced by the constant time. When the inductor current gets to the threshold of the chip, the control signal will delay for a period. This makes the inductor current rising with the increasing of the clock and leads to the load current out of control. Thus, this paper aims to design an oscillator with a variable frequency protection function.

This paper presents an oscillator with the reducing frequency applied in the DC-DC converter. When the converter works normally, the operating frequency of the oscillator is 1.5 MHz. So the inductor current has enough time to decay and prevent the power transistor damaging. After the abnormal condition, the converter returns to the normal operating mode automatically.

Based on 0.5 µm CMOS process, simulated by the HSPICE, the simulation results shows that the frequency of the oscillator linearly decreases from 1.5 MHz to 380 KHz when the feedback voltage less than 0.2 V. The maximum deviation of the oscillator frequency is only 6 per cent from −50°C to 125°C within the power supply voltage of 2.7-5.5 V.

When the light load occurs at the output stage, the oscillator frequency will decrease as the load voltage drops. The test results shows that when the circuit works in the normal condition, the oscillator frequency is 1.5 MHz. When the load decreased, the operating frequency is dropped dramatically.