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Yuan, Xiaoming. "Soft switching techniques for multilevel inverters." Florianópolis, SC, 1998. http://repositorio.ufsc.br/xmlui/handle/123456789/77541.
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Tese (doutorado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Engenharia Elétrica.Made available in DSpace on 2012-10-17T05:11:34Z (GMT). No. of bitstreams: 0Bitstream added on 2016-01-08T23:47:23Z : No. of bitstreams: 1 262713.pdf: 5373844 bytes, checksum: a249dd10d0242685c395874b9c696d96 (MD5)
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Adamson, Jesse Timothy. "Pulse Density Modulated Soft Switching Cycloconverter." DigitalCommons@CalPoly, 2010. https://digitalcommons.calpoly.edu/theses/315.
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Single stage cycloconverters generally incorporate hard switching at turn on and soft switching at turn off. This hard switching at turn on combined with the slow switching speeds of thyristors (the switch of choice for standard cycloconverters) limits their use to lower frequency applications.
This thesis explores the analysis and design of a pulse density modulated (PDM), soft switching cycloconverter. Unlike standard cycloconverters, the controller in this converter does not adjust thyristor firing angles. It lets only complete half cycles of the input waveform through to the output. This allows and requires a much greater frequency step down from the input to the output. The advantages, shortcomings and tradeoffs of this topology are explored as this converter is designed, built and tested.
The resulting cycloconverter has many deficiencies, but proves the concept of the PDM soft switching technique. Cases for further improvement and study are outlined. In the end, this converter shows much promise for applications requiring a high step down in frequency, as well as where the lower electromagnetic interference (EMI) of soft switching may be beneficial.
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Shrestha, Nabin Kumar. "High power IGBTs in soft switching applications." Thesis, University of Cambridge, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.614353.
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Mao, Hengchun. "Soft-switching techniques for high-power PWM converters." Diss., This resource online, 1996. http://scholar.lib.vt.edu/theses/available/etd-10052007-143055/.
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Hua, Guichao. "Soft-switching techniques for pulse-width-modulated converters." Diss., Virginia Tech, 1994. http://hdl.handle.net/10919/29354.
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The concept of soft-switching pulse-width-modulated (PWM) technique was proposed aimed at combining the advantages of both the conventional PWM technique and the resonant technique. This work presents four new families of soft-switching PWM converters: the zero-voltage-switched (ZVS) PWM converters, the zero-current-switched (ZCS) PWM converters, the zerovoltage- transition (ZVT) PWM converters, and the zero-current-transition (ZCT) PWM converters.
The family of ZVS- and ZCS-PWM converters are developed to improve the performance of the ZVS and ZCS quasi-resonant converters, respectively. The principles of operations of these two families of converters are presented, and the merits and limitations are assessed. A number of experimental converters are breadboarded to verify the theoretical analysis.
Both the ZVT-PWM and ZCT-PWM techniques use the concept of shunt resonant network to achieve soft-switching. In this way, the new converters achieve soft-switching without increasing the voltage and current stresses of the power switches and diodes. By using the boost topology as an example, a complete dc analysis of the ZVT-PWM and ZCT-PWM converters is presented, and the dc Voltage-conversion ratio characteristics are derived. Design trade-offs are examined, and design procedures are established. The theoretical analysis and novel features of the proposed converters are verified on a number of breadboarded converters.
Finally, the typical small-signal characteristics of the ZVT -PWM converters are analyzed and verified experimentally by using the boost converter as an example.Ph. D.
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Born, Rachael Grace. "Soft-Switching, Interleaved Inverter for High Density Applications." Thesis, Virginia Tech, 2016. http://hdl.handle.net/10919/73584.
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Power density has become increasingly important for applications where weight and space are limited. Power density is a unique challenge requiring the latest transistor technology to push switching frequency to shrink passive filter size. Furthermore, while high efficiency is an important thermal handling strategy, it must be weighed against increases in component size. Google's Little Box Challenge shone light on these challenges in pushing the power density of a 2kW inverter. The rise in electric vehicle infrastructure and demand represents a unique application for power electronics: pushing the power handling capability and functionality of bi-directional, on-board electric vehicle chargers for faster charging while simultaneously shrinking them in size.
New wide-bandgap (WBG) devices, combined with soft-switching, now allow inverters to shrink in size by pushing to higher switching frequencies while maintaining efficiency. Classic H-Bridge topologies have limited switching frequency due to hard switching. Soft switching allows inverters to operate at higher frequency while minimizing switching loss. Concurrently, interleaving can reduce current handling stress and conduction loss better than simply paralleling two transistors.
A novel interleaved auxiliary resonant snubber for high-frequency soft-switching is introduced. The design of an auxiliary resonant snubber is discussed; this allows the main GaN MOSFETs to achieve zero voltage switching (ZVS). The auxiliary switches and SiC diodes achieve zero current switching (ZCS). This soft-switching strategy can be applied to any modulation scheme. Here, it is applied to an asymmetrical unipolar H-bridge with two high frequency legs interleaved. While soft-switching minimizes switching loss, conduction loss is simultaneously reduced for high-power applications by interleaving two high frequency legs. This topology is chosen for its conduction loss reduction and bi-directional capability.Master of Science
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KRISHNA, RAJAN KRISHNA RAJAN. "Hybrid Resistive Switching Devices Based On Soft Nanocomposites." Doctoral thesis, Politecnico di Torino, 2018. http://hdl.handle.net/11583/2705510.
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Questa tesi studia la preparazione e la caratterizzazione del dispositivo di commutazione resistivo ibrido (RSD) a base di nano composito (NC) organico o memristor. La ricerca in questo campo è andata avanti per anni, ma un dispositivo appropriato con un principio di funzionamento unificato non è mai stato sviluppato nella pratica applicazione della memoria. Lo scopo principale dell'attività di ricerca è di fabbricare un RSD basato sul nanocomposito organico e concentrarsi sul suo meccanismo di funzionamento, sulle proprietà del materiale e sulle caratteristiche elettriche in dettaglio. Sono stati condotti numerosi esperimenti per ottenere un dispositivo ibrido ottimizzato che ne misura la durata, la conservazione della memoria, la finestra di memoria (On / Off) ecc. La fase iniziale della ricerca si è occupata dello sviluppo di una RSD simmetrica planare basata su Silver NC. Qui la commutazione resistiva è stata spiegata in termini di formazione indotta da campo di filamento conduttivo lungo i cluster di argento. Questo lavoro consente l'assemblaggio di un dispositivo logico, che presenta un comportamento di commutazione non volatile bipolare che viene controllato mediante l'attuale livello di conformità. Il lavoro è progredito ulteriormente con l'uso di sale d'argento insieme a Ionic Liquid (IL) in varie matrici polimeriche. Questa matrice attiva ha funzionato bene sia su simmetrici (RSD con elettrodi identici) sia su RSD asimmetriche (RSD con elettrodi realizzati in metallo diverso). L'aggiunta di Ionic Liquid a temperatura ambiente svolge un ruolo importante nell'avviare la memoria permanente e ridurre l'intervallo di tensione impostato che è stato un vero colpo d'occhio nel presente lavoro di ricerca. La presenza di ioni d'argento ben dispersi nella matrice polimerica che ha una grande diffusività, aiuta a mantenere gli stati elettrochimici reversibili che immagazzinano informazioni o bit logici sotto forma di filamento conduttivo recuperabile nella nostra matrice di commutazione ibrida basata su polimero. In questo lavoro, presentiamo uno studio dettagliato che mostra l'interazione tra il polimero e le particelle nano mediante varie tecniche. Gli RSD ibridi a matrice di commutazione discussi qui, presentano alcuni dei migliori risultati ottenuti in tutto il mondo nel campo degli RSD ibridi Polimero. Le matrici di commutazione attive preparate durante la nostra ricerca consentono una facile deposizione su vari substrati, ampliando così le potenzialità dell'elettronica stampata. La parte finale della tesi riguarda la fabbricazione e la caratterizzazione di un dispositivo di selezione ibrido a bassa potenza e ad alta velocità.This thesis investigates the preparation and characterization of organic Nano composite (NC) based hybrid Resistive switching device (RSD) or memristor. The research in this field has been going on for years, yet a proper device with a unified working principle has never been developed in practical memory application. The main aim of the research activity is to fabricate an RSD based on organic nanocomposite and to focus on its working mechanism, material properties and electrical characteristics in detail. Several experiments were conducted to obtain an optimized hybrid device measuring its endurance, memory retention, memory window (On/Off) etc. The initial stage of research dealt with the development of a planar symmetric RSD based on Silver NC. Here the resistive switching was explained in terms of field-induced formation of conductive filament along the silver clusters. This work enables the assembling of a logic device, which exhibits a bipolar non-volatile switching behaviour that is controlled by means of the current compliance level. The work further progressed with the use of silver salt along with Ionic Liquid (IL) in various polymeric matrices. This active matrix worked well both on symmetric (RSDs with identical electrodes) as well as on asymmetric RSDs (RSDs with electrodes made different metal). The addition of room temperature Ionic Liquid plays an important role in initiating permanent memory and reducing the set voltage range which was a real eye opener in the present research work. The presence of well dispersed silver ions in the polymer matrix which has a great diffusivity, helps to maintain reversible electrochemical states that store information or logic bits in the form of recoverable conducting filament in our polymer based hybrid switching matrix. In this work, we present a detailed study showing the interaction between the polymer and the Nano particles by means of various techniques. The hybrid switching matrix based RSDs discussed here, present some of the best results obtained worldwide in the field of Polymer hybrid RSDs. The active switching matrices prepared throughout our research enables an easy deposition onto various substrates thus widening printed electronics potentialities. The final part of the thesis deals with the fabrication and characterization of a low power, high speed hybrid selector device.
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Ching, Tze-wood, and 程子活. "Development of soft-switching DC-DC converters for electricpropulsion." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2001. http://hub.hku.hk/bib/B31243022.
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Vlatkovic, Vlatko. "Three-phase power conversion using soft-switching PWM techniques." Diss., Virginia Tech, 1994. http://hdl.handle.net/10919/40059.
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This dissertation addresses several key issues related to high-frequency soft-switching PWM three-phase power converters. These are:
1. Analysis, synthesis, and design of three-phase soft-switching PWM power converter topologies
2. Design of input EMI filters for three-phase converters
3. Design of microprocessor controllers for three-phase converters.
An analysis of existing soft-switching PWM techniques is performed, and two generalized soft-switching PWM converter circuit representations are derived.
Based on these representations and common topological properties of three-phase and dc-dc PWM converters, two new procedures for synthesis of three-phase soft-switching PWM converters are derived. The two procedures are used to synthesize five new three-phase soft-switching PWM converter topologies suitable for wide range of applications.
A digital signal processor-based controller implementation example is presented. It demonstrates the feasibility of producing versatile, high performance, reliable, low-cost digital controllers for soft-switching PWM three-phase power converters operating at high switching frequencies.
A new approach to the design of input filters for ac power electronic circuits
is presented here. This approach is based on the application of a vast
body of knowledge about passive L-C filters that has existed for many years,
but has not been used in power electronics. New passive and active filter pole
damping schemes are applied to high-order elliptic filters, resulting in significant
filter size reduction compared to the standard filter designs.Ph. D.
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Yeh, Chih-Shen. "Fully Soft-Switching Modulation Methods for SRC-Unfolding Inverter." Diss., Virginia Tech, 2020. http://hdl.handle.net/10919/101515.
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Isolated inverters feature the freedom in voltage step-up/down, electrical safety, and modularity. Among them, pseudo-dc-link inverters have the advantage of high efficiency due to their single-stage structure. Traditionally, pseudo-dc-link inverters are based on pulse-width-modulated converters, which suffer from hard switching, the need for auxiliary components, and/or high current stresses. Meanwhile, the series resonant converter has been prevalent in past decades due to its simplicity and high efficiency. Therefore, it is intriguing to design a single-stage inverter based on a series resonant converter.
However, there are limited papers regarding such an inverter topology. To figure out the reason, basic modulation methods proposed or implied in the literature are summarized and evaluated through circuit simulation software. It turns out each basic modulation method has at least one critical drawback in modulation range, hard switching, and/or high current stresses.
Given the deficiencies in the basic modulation methods, a hybrid modulation method is proposed here. The proposed method combines variable-frequency modulation in the high-output region and short pulse-density modulation in the low-output region. In this way, all the aforementioned critical drawbacks can be greatly alleviated. The hybrid modulation method is compared to the basic modulation methods based on three design metrics: the rms value of the resonant current, the magnetic flux of the transformer, and the turn-off current. By these design metrics that directly related to power losses, the benefit of the proposed method in terms of efficiency can be explained. Moreover, a power loss model is also established to provide more insights into the inverter's efficiency performance. It helps demonstrate how the selection of resonant tank and other factors affects the power loss distribution. Also, an inverter design procedure is introduced and a prototype is built to verify the proposed modulation method. The results show that the switching losses, especially the turn-on loss, can be well suppressed, and the losses in other passive components are well restrained. This implies the proposed method is suitable for high-frequency applications.
Other than efficiency, output waveform quality is also important for an inverter. However, the changing plant model makes the controller design difficult. Therefore, a third-order model established by other researchers has been adopted to identify the pole locations. In addition, a gain-varying method is proposed for the compensator to reduce the gain variance caused by different operating conditions. The experimental results show that without the gain-varying method, the inverter may have issues in slow tracking and/or instability.
Finally, in some scenarios, the inverter based on a series resonant converter can be regarded as a module. A multi-modular inverter can be formed by connecting the modules in an input-parallel-output-series configuration. In this case, a technique termed sequential waveform synthesis can be applied. The proposed technique can extend the region of variable-frequency modulation and shorten the region of short pulse-density modulation. This is beneficial to efficiency based on an analysis. With more than a certain amount of modules connected, the short pulse-density modulation can even be waived, which means the multi-modular inverter can be free from turn-on loss.
In summary, this dissertation focuses on developing modulation methods for inverters based on the series resonant converter. Soft-switching feature and high efficiency are the two top priorities. The analytic and experimental results are provided based on standalone applications.Doctor of Philosophy
Inverters are an important part of a modern electric power system, as they convert dc electric power into ac electric power. In some applications, inverters with electrical insulation (isolated inverters) are preferred due to the need for engineering freedom, safety, and other reasons. However, each conventional isolated inverter has some of the following drawbacks: hard-switching in semiconductor devices, high circulating current, poor transformer utilization, and high complexity. These drawbacks limit the efficiency and compactness of an inverter system, making the system less attractive to practical applications. An inverter based on a series resonant converter seems to be a solution because the series resonant converter is known for being simple and highly-efficient. However, there has yet to be a proper modulation method for it. Therefore, the main contribution of this dissertation is to propose a hybrid modulation method. With the proposed method, the inverter can operate with high efficiency. Furthermore, the hard-switching can be well suppressed, which means a high-frequency, compact design is possible. Besides the theory of the proposed method, this dissertation also includes a power loss model, a hardware design procedure, and analytic comparisons with other methods. In addition, a digital approach to control the inverter is proposed. Without it, the output voltage waveform may be highly distorted. Finally, another sequential control strategy is proposed in this dissertation for an integrated system. The integrated system is composed of multiple inverters based on a series resonant converter. With the sequential control strategy, the overall output waveform quality of the integrated system can be improved.
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Yadlapalli, Naveen. "Implementation of a Novel Soft-Switching Topology for Switched Reluctance Motor Drives." Thesis, Virginia Tech, 1999. http://hdl.handle.net/10919/34011.
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The purpose of this thesis is to design, develop, implement and test a novel soft-switching inverter topology suitable for switched reluctance motor drives. Present research being done in the field of switched reluctance motor drive inverters, including soft-switching inverters, is discussed. The novel topology is presented and the principle of operation is described in detail. The validity of the topology is verified through simulation. The various components of the system are designed and the hardware implementation is presented. Experiments carried out to verify the operation of this inverter are explained. Results are presented and comparison is made between hard switching and soft switching inverter topologies. Conclusions are drawn regarding the effectiveness of the proposed topology.Master of Science
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Jain, Nikhil. "A zero voltage switching boost converter using a soft switching auxiliary circuit with reduced conduction losses." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ59306.pdf.
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Norrga, Staffan. "On soft-switching isolated AC/DC converters without auxiliary circuit /." Stockholm, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-256.
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何永財 and Wing-choi Ho. "Loss analysis and design of a novel soft switching converter." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1997. http://hub.hku.hk/bib/B31237022.
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Bland, Michael. "An investigation of matrix converter losses and soft switching techniques." Thesis, University of Nottingham, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.289478.
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Current research and the price of semiconductors are making Matrix Converter topologies more attractive and practically viable for many applications. One of the key benefits claimed for the matrix approach is the possibility of greater power density due to the absence of a DC link. To capitalise on this it is necessary to make the input filter small by having a sufficiently high switching frequency. In order to arrive at optimised solutions in terms of filtering, heatsinking and packaging, it is important to have accurate models to predict power circuit losses as a function of operating point and switching frequency. This aim of this thesis is to further the understanding of Matrix Converter current commutation with a focus on switching losses. The commutation process is analysed in detail and a complete loss model for Matrix Converter circuits is developed. The use of circuit simulation software in the prediction of switching losses is investigated and comparisons are made with experimentally measured results. The loss model is used to compare Matrix Converter losses with a functionally equivalent sinusoidal front end inverter. A review of soft switching techniques for Matrix Converter circuits is given. A new auxiliary resonant soft switching Matrix Converter is presented which overcomes many of the problems of the previously proposed circuits. The design, construction and testing of a 6kW prototype soft switching Matrix Converter is presented to evaluate the feasibility of the topology.
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Gouker, Joel Patrick. "Implementation of a Fixed Timing Coupled Inductor Soft-Switching Inverter." Thesis, Virginia Tech, 2007. http://hdl.handle.net/10919/35357.
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In research environments, many soft switching inverters have been conceived, simulated, designed, implemented and proven to have advantages over hard switched inverters. To date however, no soft-switching inverters have reached commercial production for various reasons. The fixed timing coupled inductor soft-switching inverter is of interest because in simulation and previous implementation it exhibits load and source adaptability using simple RC timer circuitry and can be implemented with low cost active auxiliary devices. During the course of this implementation, it is noted that attempting to use excessively small/inexpensive active auxiliary devices has reliability ramifications related to device packaging. The issue of auxiliary active device reliability is conjectured upon by referencing available datasheet information, application specific requirements, device pulse testing and secondary research findings related to semiconductor failure characteristics. It is also noted that aspects of the simple fixed timing circuitry operation, in conjunction with coupled inductor and saturable inductor design, can lead to coupled inductor saturation if not properly addressed. Simulation is performed and validates various causes for this non-ideal behavior.Master of Science
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Ho, Wing-choi. "Loss analysis and design of a novel soft switching converter /." Hong Kong : University of Hong Kong, 1997. http://sunzi.lib.hku.hk/hkuto/record.jsp?B18865501.
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Bills, David Marlin. "Soft Switching Multi-Resonant Forward Converter DC to DC Application for Communications Equipment." Master's thesis, University of Central Florida, 2007. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3497.
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In the field of power electronics there is always a push to create smaller and more efficient power conversion systems. This push is driven by the industry that uses the power systems, and can be realized by new semiconductor devices or new techniques. This examination describes a novel technique for a small and highly efficient method of converting relatively high DC voltage to a very low voltage for use in the telecommunications industry. A modification to the standard Forward Resonant converter results in improvements in component stress, system efficiency, response time, and control circuitry. This examination describes background information needed to understand the concepts in DC to DC power systems, "soft-switching" topologies, and control methods for these systems. The examination introduces several topologies that are currently being used, and several types that have been previously analyzed, as a starting point for the detailed analysis of the proposed converter topology. A detailed analytical analysis is given of the proposed topology, including secondary effects, and component stresses. This analysis is compared to the results found from both Pspice simulation, and a working DC to DC converter. Finally, the topology is examined for potential improvements, and possible refinements to the model described.M.S.E.E.
School of Electrical Engineering and Computer Science
Engineering and Computer Science
Electrical Engineering MSEE
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姚建明 and Jianming Yao. "Control schemes and performance improvement of resonant snubber soft-switching inverters." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1998. http://hub.hku.hk/bib/B31220198.
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Yao, Jianming. "Control schemes and performance improvement of resonant snubber soft-switching inverters /." Hong Kong : University of Hong Kong, 1998. http://sunzi.lib.hku.hk/hkuto/record.jsp?B2051007X.
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Gurunathan, Ranganathan. "Auxiliary circuit-assisted soft switching techniques and their application to power converters." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0021/NQ45349.pdf.
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Nicholls, Jonathan Christopher. "Soft-switching performance analysis of the clustered insulated gate bipolar transistor (CIGBT)." Thesis, De Montfort University, 2009. http://hdl.handle.net/2086/2396.
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The use of Insulated Gate Bipolar Transistors (IGBT) have enabled better switching performance than the Metal Oxide Semiconductor Field effect Transistor (MOSFET) in medium to high power applications due to their lower on-state power loss and higher current densities. The power ratings of IGBTs are slowly increasing and are envisaged to replace thyristors in medium power applications such as High Voltage Direct Current (HVDC) inverter systems and traction drive controls. Devices such as the MOS Controlled Thyristor (MCT) and Emitter Switched Thyristor (EST) were developed in an effort to further simplify drive requirements of thyristors by incorporating a voltage controlled MOS gate into the thyristor structure. However, the MCT is unable to achieve controlled current saturation which is a desirable characteristic of power switching devices while the EST has only limited control. The IGBT can achieve current saturation, however, due to the transistor based structure it exhibits a larger on-state voltage in high power applications compared with thyristor based devices. MOS Gated Thyristor (MGT) devices are a promising alternative to transistor based devices as they exhibit a lower forward voltage drop and improved current densities. This current research focuses on the Clustered Insulated Gate Bipolar Transistor (CIGBT) whilst being operated under soft-switching regimes. The CIGBT is a MOS gated thyristor device that exhibits a unique self-clamping feature that protects cathode cells from high anode voltages under all operating conditions. The self-clamping feature also enables current saturation at high gate biases and provides low switching losses. Its low on-state voltage and high voltage blocking capabilities make the CIGBT suitable as a contender to the IGBT in medium to high power switching applications. For the first time, the CIGBT has been operated under soft-switching regimes and transient over-voltages at turn-on have been witnessed which have been found to be associated with a number of factors. The internal dynamics of the CIGBT have been analysed using 2D numerical simulations and it has been shown that a major influence on the peak voltage is the P well spacing within the CIGBT structure. For example, Small adjacent P well spacings within the device results in an inability for the CIGBT to switch iv on correctly. Further to this, implant concentrations of the n well region during device fabrication can also affect the turn-on transients. Despite this, the CIGBT has been experimental analysed under soft-switching conditions and found to outperform the IGBT by 12% and 27% for on-state voltage drop and total energy losses respectively. Turn off current bumps have been seen whilst switching the device in zero voltage and zero current switching mode of operation and the internal dynamics have been analysed to show the influence upon the current at turn off. Preliminary results on the Trench CIGBT (TCIGBT) under soft switching conditions has also been analysed for the first time and was found to have a reduced peak over-voltage and better switching performance than the planer CIGBT. Through optimisation of the CIGBT structure and fabrication process, it is seen that the device will become a suitable replacement to IGBT in medium power application.
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Chang, Yong-Dong, and 張永東. "SOFT-SWITCHING BOOST CONVERTERS." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/97636323026021404139.
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博士國立中正大學
電機工程研究所
99
This dissertation presents soft-switching techniques applied to boost converters. To achieve soft-switching features, passive snubbers are usually adopted because they do not require many components and complex control. However, the common limitation of a boost converter with a passive inductor-capacitor-diode (LCD) snubber is its circulation current problem, which results in high current spike flowing through the main switch at turn-on transition. It would deteriorate in converter reliability and life span. In addition, the problems of current difference and current tracking would affect the conversion efficiency. To alleviate the above mentioned drawbacks, the passive snubber is replaced with active snubbers. Three soft-switching converters: 1) a boost converter with a buck snubber, 2) a boost converter with a boost snubber and 3) a boost converter with a flyback snubber are presented in this dissertation. The boost converter with a buck snubber is first studied. It can clamp the switch voltage while inductor current iLs tracking current iLm at the main switch turn-off transition. However, clamping capacitor voltage vCs cannot be drained out during the main switch turn-on interval, resulting in significant turn-off loss. Additionally, without buffer capacitor Cb, it cannot form a resonant path, so that a high current flowing through the main switch can be avoided. According to the mentioned above, the drawback of the boost converter with an LCD passive snubber is thus relieved. Although the high current stress and the current tracking problems have been resolved, a high voltage stress and a hard-switching manner are occurred in the main switch. Thus, a boost converter with a boost snubber is introduced to alleviate the above drawback. With a boost snubber, the energy stored in Cs can be effectively transferred to the output in every switching cycle and a near ZCS feature can be attained at turn-off transition. Although the circuit has the merit of a near ZCS feature, it still suffers from high voltage stress imposed on the main switch. Moreover, the current tracking problem appears between current iLm and iLs, again. To solve the above mentioned problems, a boost converter with a flyback converter is therefore proposed. It can alleviate the drawbacks of high current and high voltage stresses imposed on the main switch at turn-on and turn-off transitions, and can achieve both near ZCS and ZVS soft-switching features. The active snubber only deals with around 1% of the full load power, and it is operated in DCM to avoid the high voltage or the current spike. The major contributions of proposed Boost+flyback converter include reducing 44 % current stress and improving around 11 times tracking capability over BCI, reducing 46 % voltage stress over Boost+buck and Boost+boost converters. Experimental results obtained from a 5 kW power rating have confirmed that the proposed configuration is attractive and feasible for high power applications.
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Lin, Chien Heng, and 林見恒. "DEVELOPMENT OF SWITCHING-MODE RECTIFIERS WITH SOFT-SWITCHING." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/05062748551174756193.
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碩士國立清華大學
電機工程學系
88
The performance of battery and the steering capability of electric vehicle is significantly influenced by the battery charger. The battery in the electric vehicle can be charged by the on-board slow charger or the off-board fast charger. Conventionally, the chargers are constructed using SCR controlled rectifiers, which draw highly- distorted current with low power factor. Thus, the purpose of this thesis is to develop a boost-type soft-switching mode rectifier (SSMR) having high power quality. The developed SSMR can be employed as a DC power supply providing well-regulated DC source, or as an adjustable-voltage source to charge the battery. In the meantime, the researches are also made on multi-module parallel operation and the construction of three-phase SSMRs using the developed single-phase SSMR. First, the specifications and the battery charging/discharging characteristics of some existing electric vehicles are investigated. According to the typical input and output voltages of charger, a single-phase boost-type SSMR is designed and implemented. The proposed SSMR is formed from the conventional SMR by simply adding an auxiliary resonant branch, and the zero voltage transition soft-switching is achieved by applying PWM switching signals with suitable time delay for the main and auxiliary switches. After the detailed derivation and analysis of the operating principle, equivalent circuit and governing equation for each mode, the quantitative design procedure of the proposed SSMR circuit components are presented. As to the design of controllers, the SSMR dynamic model is derived first and hence the current controller is designed accordingly. On the other hand, the parameters of the voltage controller are systematically and quantitatively obtained according to the dynamic model estimated at a nominal case and the given control specifications. The simulated and measured results show that the operating performances of the proposed SSMR are very close to the expected ones. The input current is regulated to be sinusoidal and kept almost in phase with the input voltage. In addition, the charging control of the series-connected batteries using the developed SSMR and the strategy for deciding the charging status are also studied. Finally, based on the proposed single-phase SSMR, the following studies about multi-module operations are performed: (i) Parallel operation control of multi-module single-phase SSMRs, good current sharing control under output voltage regulation can be obtained; and (ii) Single-phase SSMRs are connected to form three-phase SSMRs, which can be used as off-board fast battery chargers.
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Chang, Wen-Chi, and 張文祈. "Interleaved Bidirectional Soft-Switching Converter." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/62279908451745557403.
Full textAbstract:
碩士國立中正大學
電機工程研究所
101
This thesis presents design and implementation of an interleaved bidirectional dc/dc converter for dc distribution system. A four-phase interleaved bidirectional dc-dc converter is adopted, which uses switching frequency modulation method for reducing circulating loss. This circuit is operated in SCM to reduce inductor volume and increase power density. Moreover, the circuit allows synchronous mode operation to achieve zero-voltage switching. A Reneses RX62T microprocessor realizes almost all of the functions, such as circuit protection, generation of PWM signals and A/D conversion, etc. If the load voltage drops below the nominal value, the converter operates in buck mode to regulate the load voltage. On the other hand, if the load power is higher than the desired value and the voltage at the battery side is low, the converter operates in boost mode. Finally, an interleaved bidirectional DC/DC converter is implemented to verify the feasibility and characteristic of the circuit.
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Ren, Chih-Hong, and 任志宏. "Development of Modular Switching-Mode Rectifiers with Soft-Switching." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/68967281545876454588.
Full textAbstract:
碩士國立勤益技術學院
資訊與電能科技研究所
93
The purpose of this thesis is to develop a soft-switching mode rectifier (SSMR)having high power quality. The developed SSMR can be employed as a DC power supply providing well-regulated DC source, or as an adjustable-voltage source to charge the battery. In the meantime, the researches are also made on multi-module parallel operation and the construction of three-phase SSMRs using the developed single-phase SSMR. First, a single-phase SSMR with unity power factor will be designed and implemented. The circuit operations and derivation of governing quations of the proposed SSMR in various mode will be described in detail. And the quantitative design procedure of the proposed SSMR circuit components will be presented. As to the design of controllers, the SSMR dynamic model is derived first and hence the current controller is designed. On the other hand, the parameters of the voltage controller are systematically and quantitatively obtained according to the converter dynamic model derived at a nominal case by veraging method for two-time-scale(AM-TTS) and averaged power method under the given control specifications.Based on the proposed single-phase SSMR, the studies on parallel operation control of multi-module single-phase SSMRs are carried out for increasing the system capacity and reliability. With proper robust controller design, good current sharing control under good output voltage regulation performance is obtained. Finally, three-phase SSMRs formed by the connection of single-phase SSMR modules are proposed. When one single-phase module in the ∆-connected three-phase SSMR fails, it is changed to V -connection with fault detection scheme, and continue to perform the three-phase rectification. Rather good power quality can still be obtained at the price of a reduction of the system capacity. For the ∆-connected three-phase SSMRs, the connection, system capacity and the generation of current command for each single-phase SSMR is described in detail. Some simulated and measured results have been provided to verify the effectiveness of the designed controllers.
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Huang, Bi-Lun, and 黃弼侖. "Soft-Switching Bidirectional Buck-Boost Converter." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/70084250569148931050.
Full textAbstract:
碩士崑山科技大學
電機工程研究所
104
The switches of conventional converters are almost hard-switching types, which cause a sudden wave-rise on voltage and current whenever the switch is under the condition of on or off. Also, the switch may be damaged easily when often used, which leads to switch loss, low efficiency, and the rise of switch component stress. In this research, the soft-switching bidirectional buck-boost converter suggests advantages of simple construction, low weight, small volume, and low cost. Additionally, it can be adopted to other converter devices such as buck converters and boost convers. The researchers gave clear explanations toward the circuit on its theory of operational characteristics, and an analysis has been made over the circuit modes. In addition, before designing the circuits, auxiliary soft-ware IsSpice was employed to analyze the simulation waveforms of the converter mentioned above. The referential readings from the simulation waveforms were then applied to complete the actual circuits and test results. After the completion of the soft-switching bidirectional buck-boost converter, its related waveforms were measured and compared with the simulated ones for their accuracy. The result reveals that the efficiency of the circuits can be as high as 94%.
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Weng, Shang-Wen, and 翁尚文. "The Flyback Converters With Soft Switching." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/05285173235966870418.
Full textAbstract:
碩士國立高雄應用科技大學
電機工程系碩士班
92
This thesis introduces two types of soft-switching circuits and applied to flyback converter. These two different types of the soft-switching are active clamp flyback converter and variable frequency flyback converter. The active clamp flyback converter needs two switching power transistors, external leakage inductance and isolating transformer. The variable frequency flyback converter does not need the former external components. Both of them use resonant circuits to achieve the soft-switching. This thesis not only describes the system circuit principle but also verifies the theory by PSpice and Matlab software.
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Chiu, Ming-Liang, and 邱明亮. "Soft-Switching of Switched Reluctance Motor." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/06661608939656257393.
Full textAbstract:
碩士明志科技大學
電機工程研究所
98
In this thesis, soft-switching resonant converter was used. It allows a switched reluctance motor to be able to perform the soft-switching under the zero-voltage state. The circuit is composed of an auxiliary switch, resonant inductor and resonant capacitor. By using this resonant circuit, the switch can accomplish the switching action to achieve nearly zero switching loss at the very low voltage state. Moreover, the problems such as motor noise, heat loss and EMI can be improved. The switching frequency is allowed to be increased in order to improve the system performance. This article explains the details of the soft-switching circuit and the principle of the voltage current formula under the different operating mode. Moreover, the parameters for the resonant components are designed. When each phase current is tracked, the digital modulation is carried out to regulate the current’s error, the resultant signal is changed so that the DC-link voltage is forced to decrease down to zero and the zero-switching loss can be implemented.
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Huang, Yan-Hsun, and 黃彥勳. "Interleaved Buck Converter with Soft-Switching Feature." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/y73uz9.
Full textAbstract:
碩士國立東華大學
電機工程學系
100
Because of the progress of chip manufacturing technique, the transistor count inside one single CPU increases a lot, which elevates the current necessity of the chip. In order to reduce the power consumption in CPU, the supplied voltage has to be lower down. Therefore, to power CPUs, the voltage regulation modules should be featured with high current output capability at reduced voltage. The purpose of this thesis is to propose a soft-switching interleaved buck converter, which is able to provide high current at reduced output voltage. This converter is composed of several parallel-connected basic buck converter cells, associated with auxiliary capacitors. All the active switches can be soft-switched off to minimize their turn-off switching loss. Besides, synchronous rectification technique is applied to alleviate the conduction loss, which diodes might be suffered at especially high current condition. This is helpful for raising converter efficiency and power density. All the converter cells are designed with the same specification to facilitate the converter’s steady-state analysis and design. At last, a laboratory prototype circuit is built to verify the theory. The experimental results illustrate convincible agreement to theoretical analyses. The highest converter efficiency achieved is 92.5%.
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Chu, Chin-Peng, and 朱志鵬. "Implementation of A Soft-Switching Photovoltaic System." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/16721780161263367305.
Full textAbstract:
碩士國立清華大學
電機工程學系
87
The major purpose of this thesis is to develop a prototype photovoltaic system interconnected with the power grid. The major contributions are three folds. First, a new implementation of maximum power point tracking (MPPT) controller is proposed. The method not only can achieve instantaneous response instead of using the traditional perturbation and observation method with slow response but also can be operated without the temperature effect. Second, rather ideal soft- switching circuits are adopted in the converter and the inverter of the proposed system respectively to reduce the switching loss, electric stress and EMI. Finally, a prototype with a bi-directional power flow inverter is implemented and tested. Some experimental results are presented in the thesis.
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Tsai, Cheng-tao, and 蔡政道. "Interleaved Soft-Switching Converters with Coupled Inductors." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/76148334280127467435.
Full textAbstract:
博士國立中正大學
電機工程所
96
The objective of this dissertation is to improve power conversion efficiency and reduce component stresses of the power converters for high step-down voltage applications. The proposed converters with coupled inductors can extend duty ratio to reduce peak current flowing through active switches and voltage stress of diodes. To reduce switching loss and recycle the energy trapped in leakage inductance, several soft-switching techniques are applied to the proposed converters. Thus, the power conversion efficiency can be improved significantly. Power converters with an interleaved method can reduce output current ripple, handle large output current and achieve fast dynamic response. The first study in the dissertation proposes an interleaved buck converter (IBC) with a single-capacitor turn-off snubber to reduce output current ripple and switch turn-off loss. In addition, the IBC is operated at the boundary of continuous conduction mode (CCM) and discontinuous conduction mode (DCM) to reduce switch turn-on loss and free-wheeling diode reverse-recovery loss. Simulated and experimental results have verified the described merits. For high step-down voltage applications, the IBC with a single-capacitor snuber suffers from extremely low duty ratio. Thus, the component-stress problem of the IBC becomes a severe issue. To release the limitations of the IBC, an interleaved coupled-buck converter (ICBC) is proposed. It mainly uses the coupled inductor to extend duty ratio of the active switch and reduce component stresses. In the proposed ICBC, the passive-clamp and active-clamp circuits are used to reduce the switching losses of the active switch and recycle the energy trapped in leakage inductance of the coupled inductor. As compared with the IBC, the ICBC has the merits of low component stresses and higher efficiency. The performance of the proposed ICBC has been verified by various simulations and experiments. For achieving electrical isolation and high output current, a phase-shift ZVS full-bridge converter with coupled current-doubler rectifier is proposed. As the proposed converter selects a proper turns ratio of coupled inductors, copper loss of the isolation transformer, voltage stress of the rectifier diodes and its output current ripple can be reduced. From the experimental results, it can be seen that the proposed converter can achieve high efficiency over a wide load range. It is relatively suitable for high step-down voltage and high output current applications. In the dissertation, detailed analysis, design procedure, operational principle and implementation of the proposed interleaved soft-switching converters with coupled inductors have been presented. Simulated and experimental results have verified the feasibility of the discussed converters. The main contribution of this dissertation includes: 1) presenting a systematic approach to derive a new passive-lossless turn-off snubber cell, 2) applying a coupled inductor technology to improve low duty ratio of the active switches, and to reduce component stresses, 3) applying active-clamp circuits and extra resonant inductors to achieve ZVS of the active switches and reduce diode reverse-recovery losses, and 4) proposing non-isolated and isolated interleaved soft-switching converters with coupled inductors for high step-down voltage applications.
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Lin, Song-Yi, and 林宋宜. "Investigation of full bridge soft switching converters." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/75924360418788889183.
Full textAbstract:
博士國立臺灣大學
電機工程學系
86
The phase-shifted full-bridge zero-voltage-switching converter is investigated and the operating mechanism of the leading leg transition is further discussed. To overcome the problem of secondary parasitic ringing , a R-C-D clmaped snubber is used and its operating principle and design equations are derived. Based on the operating principle of phase-shifted full-bridge zero- voltage-switching converter, another kind of zero-voltage-switching converter is proposed. It retains the same advantages of phase-shifted full-bridge zero-voltage-switching converter but can be implemented using a conventional full-bridge control IC. Finally, the zero-voltage-switching technology is applied to drive plasma display panels. Novel energy recovery drivers are proposed to drive plasma display panels while minimizing energy loss and achieving soft transients.
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Fang, Shou-Yu, and 方紹宇. "Interleaved Multilevel Boost Converter with Soft-Switching." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/59817421354546987112.
Full textAbstract:
碩士國立臺灣海洋大學
電機工程學系
103
Circuit mentioned in this article, which consists of interleaved boost circuit and the switched-capacitor circuit, it can improve the conversion efficiency and higher voltage gain and variable output voltage. It is suitable for use in fuel cells. And most of the circuit will be because of the presence of the switch, and the loss of their efficiency. To solve this problem, add the soft switching technology. Improve converter switching losses even when switching at higher frequencies,it can improve this problem.This article will cooperate IsSpice derivation and application software to simulate, confirm the feasibility and practicality of this circuit.
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Wu, Chien-Te, and 吳建德. "Study of Soft-Switching Isolated Zeta Converter." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/89855051735888378570.
Full textAbstract:
碩士國立臺灣海洋大學
電機工程學系
96
Abstract This thesis is based on isolated Zeta converter and using an auxiliary circuit to achieve resonance. Main switch and auxiliary switch turn on and turn off under the condition of zero-current. The auxiliary circuit includes one auxiliary switch, two inductors, one capacitor and one diode. The converter studied in this thesis is used at battery input . The converter operates on the condition of low voltage large current .Using the technology of zero-current-switching can reduce loss and raise the efficiency.
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Lin, Shin-Yi, and 林昕毅. "Study And Realization Of Soft-switching Inverter." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/55881137132485012116.
Full textAbstract:
碩士國立宜蘭大學
電機工程學系碩士班
100
This thesis puts an emphasis on the research of single-phase soft-switching inverter which is mainly applied to the frame of single stages. All the power switches operate in the soft switching mode by using an auxiliary circuit which becomes to have the efficacy of soft switching during the process. As a result, it reduces switching loss and increases efficiency of the entire circuit. Moreover, the filter can be decreased due to the major harmonic wave of the Unipolar-switching inverter which locates at the border of the two-time frequency. Toward the end of study, an experiment of a single-phase soft-switching inverter with full power output of 2000W is presented. It proves that the percentage of efficiency increases over 90 and the total harmonic distortion is less than 5% when the output achieves 2000W.
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Yang, Sung-Pei, and 楊松霈. "Performance Improvement of Switching Power Supply Using Single Stage and Soft Switching Techniques." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/33655993075156584784.
Full textAbstract:
博士國立成功大學
工程科學系碩博士班
95
In general, the electricity is supplied by switching power converters to electronic appliances. From an energy-saving point of view, a switching power converter is required to exhibit high power factor and high power efficiency. Accordingly, an isolated zeta ac/dc power converter, a novel single-stage high power factor correction (HPFC) flyback ac/dc power converter, a novel single-stage HPFC diagonal half-bridge forward ac/dc power converter, and a novel ZCZVT forward dc/dc power converter with synchronous rectification are thus proposed in this thesis. The operating principles of the proposed single-stage HPFC power converters are presented in detail herein. Their small-signal models are also derived by using the averaging method or current injected equivalent circuit approach (CIECA). PI and minor-loop feedback controllers are then well designed to tightly regulate the output voltage in the presence of the variations in the line voltage and load resistance. Notably, the proposed converter with minor-loop feedback controller has more robust performances of the overall system than that with PI controller. Moreover, since the proposed single-stage HPFC converters are operated in DCM+DCM, it not only inherently has high power factor, but also avoids suffering from high voltage stress across the bulk capacitor at light loads. To this end, the inductances of the proposed converters should be well designed to ensure that the inductor currents operate in DCM. In addition, the capacitances of the bulk and output capacitors in the proposed converters are also designed to satisfy the specified ripple voltage percentages. Finally, the proposed converters are implemented based on the design specification. The experimental results successfully validate the theoretical analysis, mathematical model and the performances of the overall system. The proposed novel ZCZVT forward power converter with synchronous rectification is operated at 300 kHz and has high power efficiency of 89 %, which is 15 % greater than that of the conventional forward converter. Moreover, the flux of transformer can be reset without a tertiary winding, and thus the size of transformer is effectively reduced. Based on the operating principle of the converter, the soft-switching conditions are derived. It then follows from these conditions that the resonant components are designed. Finally, a prototype of the proposed ZCZVT converter is built to validate the theoretical analysis and the soft-switching performances. The power losses for key components are well estimated. Notably, the estimated efficiency is very close to the experimental result. In the further work, if soft switching techniques can be successfully applied to a HPFC power converter, then the overall efficiency of the power electronics system will be effectively increased.
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Pan, Hung-Ye, and 潘紘業. "Novel Soft-Switching Interleaved Boost Converters:Analysis and Implementation." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/53091119139623042309.
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黃照霖. "A Study of Boost PWM Soft-Switching Converter." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/45911820671121329664.
Full textAbstract:
碩士國立臺灣海洋大學
電機工程學系
96
Abstract This thesis presents Boost converter with a passive snubber to reduce the switching losses. The circuit topology of the converter consists of traditional Boost converter and a passive snubber, the snubber composed of a capacitor, an inductor and diodes, is able to operate with soft switching in a pulse width modulation and improve the traditional switching power converter since high switching frequency accompanied high switching losses. Finally simulation and experimental results are given to verify it’s correctly and practicability.
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Tseng, Ching-Jung, and 曾勁榕. "Analysis and Design of Soft-switching Power Converter." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/33359774658105701715.
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wu, chin-chung, and 吳錦長. "Space-Vector PWM and Soft-Switching Inverter Design." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/31901818179071106165.
Full textAbstract:
碩士國立交通大學
電機與控制工程系
87
Soft-switching techniques ( zero current switching or zero voltage switching ) applied to power inverter can substantially improve the performances, allowing high frequency operation and minimization of acoustic noise and EMI, reduction of switching losses, limitation of dv/dt and di/dt stress in the power devices .The quasi-resonant dc link soft switching circuit used in this paper needs additional components such as two switches, a diode, an inductor and a capacitor, the two switches are also soft switching, which produces a minimum losses. The quasi-resonant dc link circuit notching the bus voltage and allowing the switches of the inverter just switching at zero voltage. The modulation technique we adapt is Space-Vector PWM and refuse traditional sinusoidal PWM, because the SPWM can't completely utilize the dc link voltage, current ripple is badly and analogical mode control, which is complex and not easy to maintain. Now the digitalization design has become the standard of the drive- controller, so the superior performance and easy-digitized SV-PWM has become major method in the PWM techniques. The control of the system are processed by the chips FLEX PF10KAL10LC C84-4 of Altera company. Whose hardware description language can scrimp the time in design and makes the system more easily to maintain and modify. The experiment results have shown that our soft-switching circuit works very stable and reliably.
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Liu, Chia-Hua, and 劉家樺. "Study and realization of a soft-switching inverter." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/08756444665455202279.
Full textAbstract:
碩士國立宜蘭大學
電機工程學系碩士班
98
The thesis proposed a zero-current-switching (ZCS) inverter. The proposed soft-switching inverter is configured by a full-bridge series-resonant inversion (FB-SRI). The presented FB-SRI is operated by frequency modulation control. The output sinusoidal voltage is synthesized by a series of equal-amplitude quasi-sinusoidal pulses (QSPs) .The presented soft-switching inverter can use a simple LC filter to filter the undesired harmonics and get the sinusoidal voltage with low total harmonic distortion. The FB-SRI is realized soft-switching behavior without any auxiliary switches and auxiliary circuit. The soft-switching technique is operated by frequency modulation with a constant-on time control and series-resonant method to performed soft-switching behavior. A design example of a 1000-W single-phase soft-switching inverter is examined to assess the system performance. The power efficiency is over 90% at the rated output power. The total harmonic distortion (THD) at the rated output power is within 5%.
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Chiu, Chih-Yi, and 邱至毅. "Analysis of Soft-Switching Bidirectional Buck-Boost Converter." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/93158265739344129527.
Full textAbstract:
碩士國立臺灣海洋大學
電機工程學系
101
Abstract The purpose of this thesis is to analyze the operation of the bidirectional Buck-Boost converter and conversion efficiency, and to explore the process of zero-voltage switching, Buck mode and Boost mode switching element driving voltage and the voltage across the switching waveform. Consider the effects brought about by the resonant capacitor, arising from the use of parasitic elements with resonance technology zero-voltage switching to reduce switching losses, and reduce the adverse effects caused by the parasitic elements and improve the conversion efficiency. When fully loaded, it can improve the stability of the system. Use of IsSpice software simulation of this circuit converters discussed in the case of the CCM and DCM, the waveform of the voltage and current of the converter element of this circuit.
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Tsai, Hsien-Yi, and 蔡憲逸. "Novel Soft-Switching Bridgeless Power Factor Correction Circuits." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/84640922552273594209.
Full textAbstract:
博士國立臺灣大學
電機工程學研究所
99
Power factor correction (PFC) has become almost a must for off-line power applications nowadays. Despite intensive research in the past decade, this is still a hot-research topic among power electronic field because of the “green” push for the future electric power applications. About ten years ago, there was a PFC power-stage configuration named” Bridgeless” reported. In this configuration, the diode bridge conventionally used PFC applications can be removed and therefore resulting in lower conduction power loss for the applications. The main focus of this dissertation is about soft-switching “Bridgeless” PFC (BPFC) circuits which feature improved efficiency. In the dissertation, three classes of soft-switching BPFC circuits are proposed. The first class is a zero-voltage transition BPFC in which an assistant circuit is used to achieve soft switching in the main power switches. However, the assistant switch is still turned off by hard switching. The second class is a zero-voltage zero-current BPFC circuit in which soft switching is achieved not only for the main switches but also for the assistant switch. And the third class is an extension of the first class to a three-phase PFC circuit. Different circuit variations are also proposed to the above three classes. Computer simulations and experimental results are presented in the dissertation. Design guidance is also included. Improvements of efficiencies, compared to conventional hard-switching circuits are in the range of one to two percentage points which is a significant improvement.
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Ming-HsienCheng and 鄭明憲. "Improved Soft-Switching Interleaved Half-Bridge Flyback Converters." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/67zm33.
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Lin, Chih-Ju, and 林志儒. "Non-Isolated Buck-Type Converter with Soft Switching." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/ktp547.
Full textAbstract:
碩士國立臺北科技大學
電力電子產業研發碩士專班
96
In this thesis, a non-isolated buck-type converter, together with half resonance and zero voltage transition to achieve zero current switching and zero voltage switching, is presented, in which the source terminal of the MOSFET switch is connected to the ground so as to make this switch easy to drive. In addition, the pulse width modulation (PWM) control technique is utilized in this converter so as to render the required output filter easy to design. By doing so, the problems in the electromagnetic interference (EMI) and power dissipation are reduced and hence the efficiency of this converter is upgraded. In this thesis, the theoretical derivation is firstly introduced, and secondly the simulated and experimental results are provided to demonstrate the effectiveness of the proposed topology.
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Huang, Yi-Min, and 黃以民. "Analysis and Design of Flyback Converters with Soft Switching." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/69574803905433782557.
Full textAbstract:
碩士國立臺灣大學
電機工程研究所
84
Due to the lower cost and the circuit simplicity, the flyback converter has been widely used in the low power applications be- low two hundred of watts for a long time. To suppress the voltage spikes caused by the switching noise of the main power transistor, a set of snubber circuit and RCD- clamp scheme (composed of a resistor,a capacitor and a diode) are usually employed. Its disadvantage is that the capacitor of the snubber circuit must be large enough for reducing voltage spikes. And the stored energy in the capacitor is dissipated in the snubber resistor. Generally speaking, the larger the snubber capacitor is used, the lower the voltage spike produces. However, it will generate more power dissipation and lead to the reduction of conversion efficiency. This thesis finds one way that can achieve softswitching in flyback converters, and resolve the problems of efficiency and voltage spikes.The new way still maintains the traditional merits of the flyback converters.
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peng, Shin wei, and 彭信瑋. "A Soft Switching Motor Drive Using an Active Snubber." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/2fs76s.
Full textAbstract:
碩士國立臺北科技大學
車輛工程系所
101
This thesis proposes a pulse-width-modulation (PWM) inverter with the soft switching for the brushless DC motor (BLDCM) of the electric scooter. This motor drive could reduce switching losses, increase driving and regenerative efficiency. Moreover, this system could obtain some advantages, such as low cost and high efficiency which the capacitance is easily designed in the switched capacitor snubber. In the switching control method of this motor driver, a bidirectional conduction of inverter is used to match the relationship of the three-phase voltage of BLDCM, besides, the each internal winding of the BLDCM could be operated in a inductor. Thus a boost circuit is made up of the inductors, the MOSFET power switches, the motor electromotive force (EMF) and the input DC source. By this switching control approach, a reverse torque could be resulted in the electric brake that transfers the braking kinetic into the electric energy to the battery, thus the driving range of EV could be increased by this approach. Finally, this thesis uses a hub motor with 48V/750W to build an experimental system and some experimental results are provided to verify the correctness and feasibility of the proposed schemes.
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Pan, Pin-En, and 潘品恩. "A Soft-Switching Modular Three-Phase AC Voltage Regulator." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/nbhsx7.
Full textAbstract:
碩士國立宜蘭大學
電機工程學系碩士班
102
This thesis presents a soft-switching three-phase AC voltage regulator, which includes a modular three-phase transformer series compensation AC voltage regulator, a three-phase capacitor series compensation AC voltage regulator and a three-phase unified power quality conditioner. All of the proposed voltage regulators can compensate the voltage disturbances such as under-voltage, over-voltage, voltage sag, voltage swell and three-phase unbalanced load. The proposed three-phase AC voltage regulators are modular configuration that each phase is composed of a three-arm topology which operates as a rectifier and an inverter. The low frequency arm is switched at line-frequency synchronized to the voltage source to achieve low switching losses. The rectifier arm is switched at high switching frequency to perform power factor correction and simultaneously transfers the power demand by the load to the dc link capacitor. The inverter arm is also switched at high switching frequency for the output voltage regulation. Using simple resonant units, all main switches of high frequency arm are operated at zero-voltage-switching (ZVS) turn-on, while all auxiliary switches are operated at zero-current-switching (ZCS) turn-off. The topology has the advantages of reducing the switching losses, and EMI greatly. Besides operating at unipolar PWM voltage switching, the input current and the output voltage harmonics can be reduced. Moreover, the proposed feed forward controller, based on the energy balance concept, is proposed to control the voltage of energy-storage capacitors. The energy change in energy-storage capacitors can be fast compensated so that the transient performance can be improved. Finally, some simulation and experimental results are presented for verification.
50
Syu, Ming-Lang, and 許銘朗. "Study of a Modular Soft-Switching Digital Inverter System." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/24065623625086913932.
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碩士國立宜蘭大學
電機工程學系碩士班
97
This thesis presents a filed programmable gate array (FPGA)-based control circuit for controlling the soft-switching sinusoidal pulse-width modulated inverter. The proposed inverter has a new auxiliary resonant commutation cell. It provides that all main switching power devices in the soft-switching inverter operate at zero-voltage-switching turned-on and the auxiliary switches operate at zero-current-switching turned-off. In addition, this thesis presents an improved control scheme to minimize the operation of auxiliary resonant circuit for efficiency improvement. This thesis also proposed a multiple-loop control scheme for this soft-switching inverter control circuit to achieve good output voltage waveform and fast dynamic response. Furthermore, two modules are connected to form a digital v-connected soft-switching three-phase inverter. Finally, some simulation and experimental results are presented for verification.