Power converters used in high reliability radiation hardened space applications trail their commercial counterparts in terms of power density and efficiency. This is due to the additional challenges that arise in the design of space rated power converters from the harsh environment they need to operate in, to the limited availability of space qualified components and field demonstrated power converter topologies. New radiation hardened Gallium Nitride (GaN) Field Effect Transistors (FETs) with their inherent radiation tolerance and superior performance over Silicon Power Metal Oxide Semiconductor Field Effect Transistors (MOSFETs) are a promising alternative to improve power density and performance in space power converters. This thesis presents the considerations and design of a practical implementation of the Phase Shifted Full Bridge DC-DC Isolated converter with synchronous rectification for space applications. Recently released radiation hardened GaN FETs were used in the Full Bridge and synchronous rectifier power stages. A survey outlining the benefits of new radiation hardened GaN FETs for space power applications compared to current radiation hardened power MOSFETs is included. In addition, this work presents the overall design process followed to design the DC-DC converter power stage, as well as a comprehensive power loss analysis. Furthermore, this work includes details to implement a conventional hard-switched Full Bridge DC-DC converter for this application. An efficiency and component stress comparison was performed between the hard-switched Full Bridge design and the Phase Shifted Full Bridge DC-DC converter design. This comparison highlights the benefits of phase shift modulation (PSM) and zero voltage switching (ZVS) for GaN FET applications. Furthermore, different magnetic designs were characterized and compared for efficiency in both converters. The DC-DC converters implemented in this work regulate the output to a nominal 20 V, delivering 500 W from a nominal 100 V DC Bus input. Complete fault analysis and protection circuitry required for a space-qualified implementation is not addressed by this work. / MS / Recently released radiation-hardened Gallium Nitride (GaN) Field Effect Transistors (FETs) offer the opportunity to increase efficiency and power density of space DC-DC power converters. The current state of the art for space DC-DC power conversion trails their commercial counterparts in terms of power density and efficiency. This is mainly due to two factors. The first factor is related to the additional challenges that arise in the design of space rated power converters from the harsh environment they need to operate in, to the limited availability of space qualified components and field demonstrated converter topologies. The second factor lies in producing reliable radiation hardened power Metal Oxide Semiconductor Field Effect Transistors (MOSFETs). GaN FETs not only have better electrical performance than power MOSFETs, they have also demonstrated inherent tolerance to radiation. This results in less structural device changes needed to make GaN FETs operate reliably under high radiation compared to their MOSFETs counterparts. This work outlines the design implications of using newly released radiation hardened GaN FETs to implement a fixed frequency isolated Phase Shifted Full Bridge DC-DC converter while strictly abiding to the design constraints found in space-power converter applications. In addition, a one-to-one performance comparison was made between the soft-switched Phase Shift modulated Full Bridge and the conventional hard-switched Full Bridge DC-DC converter. Finally, different magnetic designs were evaluated in the laboratory to assess their impact on converter efficiency.

The main goal of this project was an optimization of DC-DC converter design from company Meatest with regards to its efficiency, minimalizing power loses and radiated electromagnetic inference, while maintaining its price on reasonable level. The first part of this paper is introduction to the most common converter topologies. In the second part, design and optimization of converter are discussed. The third part is about measurement automatization in Simple. Measurements of converter prototype can be found in fourth part.

Modern arc welding machines utilize controllable high frequency DC/DC power supply with high dynamic and steady state current regulation performance. In the design robustness, small size and low weight, low complexity, and high efficiency are the defining criteria. The most suitable approach for a 5 kW arc welding machine power supply application is the high frequency Full-Bridge Phase-Shifted Zero Voltage Switching (FB-PS-ZVS) DC/DC converter with an isolation transformer. This converter not only gives the advantage of zero voltage switching for a wide load current range, it also provides reduced Electromagnetic Interference (EMI) and reduced component stress compared to standard PWM converters. In this thesis a FB-PS-ZVS DC/DC converter with 5 kW power rating is designed for modern arc welding machine applications. IGBTs are utilized at 50 kHz switching frequency for high efficiency and control bandwidth. The output current of the DC/DC converter is controlled via a Digital Signal Processor (DSP) control platform. The performance of the designed DC/DC converter is evaluated via the computer simulations and the experimental study of the constructed prototype.

In this thesis a two-stage AC/DC/DC power converter is designed and implemented. The AC/DC input stage of the converter consists of the two&amp / #8211 / phase interleaved boost topology employing the average current mode control principle. The output stage consists of a zero voltage switching phase shifted full bridge (ZVS&amp / #8211 / PS&amp / #8211 / FB) DC/DC converter. For the input stage, main design goals are obtaining high input power factor, low input current distortion, and well regulated output dc voltage, and obtaining these attributes in a power converter with high power density. For the input stage, the interleaved structure has been chosen in order to obtain reduced line current ripple and EMI, reduced power component stresses, and improved power density. The control of the pre&amp / #8211 / regulator is provided by utilizing a new commercial monolithic integrated circuit, which provides interleaved continuous conduction mode power factor correction (PFC). The output stage is formed by utilizing the available prototype hardware of a ZVS&amp / #8211 / PS&amp / #8211 / FB DC/DC converter and mainly the system integration and controller design and implementation studies have been conducted. The converter small signal model is derived and utilizing its transfer function and employing voltage loop control, the output voltage regulator has been designed. The output voltage controller is implemented utilizing a digital signal processor (DSP). Integrating the AC/DC preregulator and DC/DC converter, a laboratory AC/DC/DC converter system with high overall performance has been obtained. The overall system performance has been verified via computer simulations and experimental results obtained from laboratory prototype.

This thesis presents a parallel-series two-bridge DC/DC converter topology with the ability to operate with ZVS over a wide input and load range. The intended application is power conditioning systems (PCS) of photovoltaic (PV) arrays used in hybrid renewable energy system architectures. The proposed topology provides two degrees of freedom which allows the PV-PCS to regulate the DC-link voltage, while tracking the maximum power point (MPP) of the PV array. This topology distributes the main power into two bridges and the phase-shift between the two bridges and provides another degree of freedom for the PCS to track the MPP. The proposed topology is also able to achieve soft-switching over a wide range. The power conditioning system shows a modular structure to efficiently transfer the power to the load as the main power is divided between two bridges. In addition, the proposed control scheme provides complete decoupling between the input side controller from the output side controller in order to perform MPPT and regulate the the DC-link voltage simultaneously. A 2kW Experimental prototype has been provided to validate the feasibility and performance of the converter. Experimental results prove that the converter is able to regulate the DC-link voltage and track the maximum power extracted from the PV array simultaneously. / Thesis (Master, Electrical & Computer Engineering) -- Queen's University, 2012-04-18 19:51:43.405

Σκοπός της παρούσας εργασίας είναι η μελέτη, η προσομοίωση και η κατασκευή ηλεκτρονικού μετατροπέα ισχύος, για τη διασύνδεση με το ηλεκτρικό δίκτυο, πηγών ηλεκτρικής ενέργειας που προέρχονται από ανανεώσιμες μορφές, συγκεκριμένα από την ανεμογεννήτρια και το φωτοβολταϊκό σύστημα που είναι εγκατεστημένα στο Εργαστήριο Ηλεκτρομηχανικής Μετατροπής Ενέργειας (Ε.Η.Μ.Ε). / This paper is about study, simulation, design and constraction electronic power converter to connect with the electric grid, sourses of electricity generated by renewable energy, specifically from wind and solar.

Orientador: Dr. José L. Azcue Puma / Dissertação (mestrado) - Universidade Federal do ABC, Programa de Pós-Graduação em Engenharia Elétrica, 2016. / Este trabalho apresenta o estudo, modelagem e projeto de um sistema de conversão de energia para a conexão de um módulo fotovoltaico com a rede elétrica. Nesta pesquisa são abordados três conversores para adequar a energia gerada por um painel fotovoltaico e conectá-la à rede elétrica. O primeiro conversor é um Boost intercalado de dois níveis encarregado de implementar o MPPT (Maximum Power Point Tracking), o segundo conversor é um Ressonante LLC que realiza o isolamento galvânico e o terceiro conversor é um inversor em ponte completa que mantém a tensão de barramento em um valor determinado e realiza a conversão de corrente contínua para corrente alternada. Os três conversores são projetados, calculando os elementos passivos que os compõem e simulando os circuitos obtidos. Também, é realizada a modelagem dos conversores e o projeto dos controladores utilizando a análise de pequenos sinais. Os resultados de simulação são apresentados utilizando os softwares PSIM e MATLAB. Na parte experimental são verificados os dois primeiros conversores usando o kit High Voltage Isolated Solar MPPT fabricado pela Texas Instruments. / This work presents the study, modeling and design of a photovoltaic conversion system for the connection of a photovoltaic module with the grid. In this research three converters are approached to adequate the generated energy for a photovoltaic panel and to transfer the energy to the grid. The first converter is an interleaved two-level boost responsible for implementing the MPPT (Maximum Power Point Tracking) the second converter is a Resonant LLC that performs galvanic isolation and the third converter is a complete bridge inverter that keeps the bus voltage at a certain value and performs the conversion of continuos current to alternating current. The three converters are designed, calculating the passive elements that compose them and simulating the obtained circuits. Also, the modeling of the inverters and the design of the controllers are performed using small signal analysis. Simulation results are presented using the PSIM and MATLAB software. In the experimental part the first two inverters are verified using the High Voltage Isolated Solar MPPT kit manufactured by Texas Instruments.

No description available.

Bi-directional DC-DC converters are used for applications that require a flow of energy in two directions, while a wide range converter offer efficient operation over a wide range of input and output voltages. However, an efficient technology that is both bi-directional and Wide Input Wide Output (WIWO), currently, does not currently exist.   To find a suitable topology, the work began by surveying the existing literature and when a potentially suitable solution was identified, it was evaluated via simulation.   Using a wide range, unidirectional topology as the starting point, a converter topology was designed, capable of reconfiguring its transformer ratios by controlling the synchronization of its switches.   By aiming to use soft switching in simulation, this topology was improved to reach 92\% efficiency in the forward mode and 95\% in the reverse mode of operation. Furthermore, a prototype of this converter was developed that reached 82\% efficiency. While this prototype requires a better controller, hardware optimization and testing for optimal performance, the proposed technology was verified via simulation to work as a WIWO converter that is also bi-directional.

A systematic and versatile method to derive accurate and efficient Circuit Oriented Large Signal Average Models (COLSAMs) that approximate the slow dynamics manifold of the moving average values of the relevant state variables for Pulse-Width Modulated (PWM) dc to dc and three-phase to dc power converters is developed. These COLSAMs can cover continuous conduction mode (CCM) as well as discontinuous conduction mode (DCM) of operation and they are over one order of magnitude cheaper, computation wise, than the switching models. This method leads primarily to simple and effective input-output oriented models that represent transfer as well as loading characteristics of the converter. Sine these models consist of time invariant continuous functions they can be linearized at an operating point in order to obtain small-signal transfer functions that approximate the dynamics of the original PWM system around an orbit. The models are primarily intended for software circuit simulators (i.e. Spice derived types, Saber, Simplorer, etc), to take advantage of intrinsic features such as transient response, linearization, transfer function, harmonic distortion calculations, without having to change simulation environment. Nevertheless, any mathematics simulator for ordinary differential equations can be used with the set of equations obtained through application of Kirchoff's laws to the COLSAMs. Furthermore, the COLSAMs provide physical insight to help with power stage and control design, and they allow easy interconnection among themselves, as well as with switching models, for complete analysis at different scales (time, signal level, complexity; interconnectivity). A new average model for the Zero-Voltage Switched Full-Bridge (ZVS-FB) PWM Converter is developed with the above method and its high accuracy is verified with simulations from a switching behavioral model for several circuit component values for both CCM and DCM. Intrinsic positive damping effects and special delay characteristics created by an energy holding element in a saturable reactor-based Zero-Voltage Zero-Current Switched Full-Bridge (ZVZCS-FB) PWM converter are explained for the first time by a new average model. Its large signal predictions match very well those from switch model simulations whereas its small-signal predictions are verified with experimental results from 3.5 kW prototype modules. The latter are used in a multi-module converter to supply the DC power bus in and aircraft. The design of control loops for the converter is based on the new model and its linearization. The ZVZCS-FB PWM converter's average model above is extended to deal with interconnection issues and constraints in a Quasi-Single Stage (QSS) Zero-Voltage Zero-Current Switched (ZVZCS) Three-Phase Buck Rectifier. The new model reveals strong nonlinear transfer characteristics for standard Space Vector Modulation (SVM), which lead to high input current distortion and output voltage ripple inadmissible in telecommunications applications. Physical insight provided by this average model led to the development of a combined modified SVM and feed-forward duty-cycle compensation scheme to reliably minimize the output voltage ripple. Experimental results from a 6 kW prototype validate large signal model for standard and modified SVM, with and without duty-cycle compensation scheme. / Ph. D.