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Mohd, Mukhtar Nurhakimah. "Efficiency Improvement Techniques for Isolated Flyback and Forward Bidirectional DC-DC Converters." Thesis, University of Sydney, 2020. https://hdl.handle.net/2123/23127.
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The information age introduced myriad means for individuals and organisations to stay connected and feel informed. Among those means, email arose as one of the most successful and ubiquitous communication technologies to be enabled via internet access. Today it continues to grow in both the volume of traffic and users each year. We now know that this has resulted in an overabundance of information, which is proving difficult for people to mentally process and productively manage. This is known as “Information overload” and email’s part in this has been termed “email overload”. Among this surplus of communication, important time-related information (temporal information) can easily become buried. This makes information recognition and retrieval an issue and it can cause late appointments, incomplete tasks and missed deadlines, the result of which is increasing stress and cognitive burden. Email applications and related technologies struggle to provide their users with adequate means for identifying and managing temporal information, which arrives embedded within email messages. Despite the sequential nature of time and task obligations received in email messages, email applications offer little to no native support for organising temporal information. It is assumed that users will utilise calendar and task-list applications to manage their time instead. In this research we conducted seven mixed method studies ranging from interviews through to A/B testing to understand the obstacles and opportunities that exist in facilitating temporal information management in email. Among our findings, we observed that the reliance on calendaring was creating distraction, dissuasion and a flawed mental representation of time. We combined our initial results with our background readings to devise solutions to these problems. We tested these solutions by creating a series of increasing-fidelity prototypes that were evaluated by users. The results informed the recommendations we arrived at for improving temporal information awareness and management in email and similar technologies. As a result of conducting a prolonged research project utilising the Research Through Design (RTD) framework, we also contribute a synthesised model of the Design process that articulates lateral thinking by Designers. Finally we contribute a functional prototype that demonstrates the phenomenological advantage in applied research methodologies. In doing so we contribute further knowledge and offer practical recommendations for the Design of temporal information in User Interfaces. We also further discourse on the diverse mental faculties employed during an iterative Design process and the value of prototypes as a conduit for Design knowledge generation.
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Xi, Youhao. "Zero voltage switching flyback and forward converter topologies." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ40214.pdf.
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Ahmad, Nisar. "Design and Implementation of a High Frequency Flyback Converter." Thesis, Mittuniversitetet, Avdelningen för elektronikkonstruktion, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-24598.
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The power supply designers choose flyback topology due to its promising features of design simplicity, cost effectiveness and multiple outputs handling capability. The designed product based on flyback topology should be smaller in size, cost effective and energy efficient. Similarly, designers focus on reducing the circuit losses while operating at high frequencies that affect the converter efficiency and performance. Based on the above circumstances, an energy efficient open loop high frequency flyback converter is designed and operated in MHz frequency region using step down multilayer PCB planar transformer. The maximum efficiency of 84.75% is observed and maximum output power level reached is 22.8W. To overcome the switching losses, quasi-resonant soft switching technique is adopted and a high voltage CoolMOS power transistor is used.
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Tian, Feng. "Pulse Frequency Modulation ZCS Flyback Converter in Inverter Applications." Doctoral diss., University of Central Florida, 2009. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4266.
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Renewable energy source plays an important role in energy co-generation and distribution. A traditional solar-based inverter system has two stages cascaded, which has simpler controller but low efficiency. A new solar-based single-stage grid-connected inverter system can achieve higher efficiency by reducing the power semiconductor switching loss and output stable and synchronizing sinusoid current into the utility grid. In Chapter 1, the characteristic I-V and P-V curve of PV array has been illustrated. Based on prediction of the PV power capacity installed on the grid-connected and off-grid, the trends of grid-tied inverter for DG system have been analyzed. In Chapter 2, the topologies of single-phase grid-connect inverter system have been listed and compared. The key parameters of all these topologies are listed in a table in terms of topology, power decoupling, isolation, bi-directional/uni-directional, power rating, switching frequency, efficiency and input voltage. In Chapter 3, to reduce the capacitance of input filter, an active filter has been proposed, which will eliminate the 120/100Hz low frequency ripple from the PV array's output voltage completely. A feedforward controller is proposed to optimize the step response of PV array output voltage. A sample and hold also is used to provide the 120/100Hz low frequency decoupling between the controller of active filter and inverter stage. In Chapter 4, the single-stage inverter is proposed. Compared with conventional two-stage inverter, which has two high frequency switching stages cascaded, the single-stage inverter system increases the system efficiency by utilizing DC/DC converter to generate rectified sinusoid voltage. A transformer analysis is conducted for the single-stage inverter system, which proves the transformer has no low-frequency magnetic flux bias. To apply peak current mode control on single-stage inverter and get unified loop gain, adaptive slope compensation is also proposed for single-stage inverter. In Chapter 5, a digital controller for single-stage inverter is designed and optimized by the Matlab Control Toolbox. A Psim simulation verified the performance of the digital controller design. In Chapter 6, three bi-directional single-stage inverter topologies are proposed and compared. A conventional single-stage bi-directional inverter has certain shortcoming that cannot be overcome. A modular grid-connect micro-inverter system with dedicated reactive energy processing unit can overcome certain shortcoming and increase the system efficiency and reliability. A unique controller design is also proposed. In Chapter 7, a PFM ZCS flyback inverter system is invented. By using half-wave quasi-resonant ZCS flyback resonant converter and PFM control, this topology completely eliminates switching loss. A detailed mathematical analysis provides all the key parameters for the inverter design. As the inductance of transformer secondary side get smaller, the power stage transfer function of PFM ZCS flyback inverter system demonstrates nonlinearity. An optimized PFM ZCS flyback DC/DC converter design resolves this issue by introducing a MOSFET on the secondary side of transformer. In Chapter 8, experimental results of uni-direcitonal single-stage inverter with grid-connection, bi-directional single-stage inverter and single-stage PFM ZCS flyback inverter have been provided. Conclusions are given in Chapter 9.<br>Ph.D.<br>School of Electrical Engineering and Computer Science<br>Engineering and Computer Science<br>Electrical Engineering PhD
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Leung, Hong Man. "SPICE simulation and modeling of DC-DC flyback converter." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/36643.
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Zhang, Zhemin. "High-frequency Quasi-square-wave Flyback Regulator." Diss., Virginia Tech, 2016. http://hdl.handle.net/10919/77434.
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Motivated by the recent commercialization of gallium-nitride (GaN) switches, an effort was initiated to determine whether it was feasible to switch the flyback converter at 5 MHz in order to improve the power density of this versatile isolated topology. Soft switching techniques have to be utilized to eliminate the switching loss to maintain high efficiency at multi-megahertz. Compared to the traditional modeling of zero-voltage-switching quasi-square-wave converters, a numerical methodology of parameters design is proposed based on the steady-state model of zero-voltage switching quasi-square-wave flyback converter. The magnetizing inductance is selected to guarantee zero-voltage switching for the entire input and load range with the trade-off design for conduction loss and turn-off loss.
A design methodology is introduced to select a minimum core volume for an inductor or coupled inductors experiencing appreciable core loss. The geometric constant Kgac = MLT/(Ac2WA) is shown to be a power function of the core volume Ve, where Ac is the effective core area, WA is the area of the winding window, and MLT is the mean length per turn for commercial toroidal, ER, and PQ cores, permitting the total loss to be expressed as a direct function of the core volume. The inductor is designed to meet specific loss or thermal constraints. An iterative procedure is described in which two- or three-dimensional proximity effects are first neglected and then subsequently incorporated via finite-element simulation. Interleaved and non-interleaved planar PCB winding structures were also evaluated to minimize leakage inductance, self-capacitance and winding loss. The analysis on the trade-off between magnetic size, frequency, loss and temperature indicated the potential for a higher density flyback converter.
A small-signal equivalent circuit of QSW converter was proposed to design the control loop and to understand the small-signal behavior. By adding a simple damping resistor on the traditional small-signal CCM model, it can predict the pole splitting phenomenon observed in QSW converter. With the analytical expressions of the transfer functions of QSW converters, the impact of key parameters including magnetizing inductance, dead time, input voltage and output power on the small-signal behavior can be analyzed. The closed-loop bandwidth can be pushed much higher with this modified model, and the transient performance is significantly improved.
With the traditional fix dead-time control, a large amount of loss during dead time occurred, especially for the eGaN FETs with high reverse voltage drop. An adaptive dead time control scheme was implemented with simple combinational logic circuitries to adjust the turn on time of the power switches. A variable deadtime control was proposed to further improve the performance of adaptive dead-time control with simplified sensing circuit, and the extra conduction loss caused by propagation delay in adaptive dead-time control can be minimized at multi-megahertz frequency.<br>Ph. D.
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Chiang, Cheng-Chung, and 江成忠. "Flyback Converter with Synchronous Rectification." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/23263717278325510167.
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碩士<br>中原大學<br>電機工程研究所<br>94<br>Abstract
The Flyback converter topology is widely used for commercial low power applications. Its great attraction is that it has no secondary output inductors. The consequent savings in cost and volume is a significant advantage. However, a lot of the power losses are concentrated in secondary diode rectifiers, and primary switches. Research efforts should therefore be focused on the development of relatively simple topologies that can reduce these losses. In this thesis, a Flyback converter with synchronous rectification output is presented for low output voltage and high output current applications. The power losses in the secondary rectification stage and the primary switches can be significantly reduced. The presented architecture exhibits extreme simplicity and lower cost while providing high power density. The detailed operating principles and design criteria for the presented converter are described. Experimental results for a laboratory prototype are shown to verify the feasibility.
Keywords：Active Clamp, Flyback Converter, Synchronous Rectification, Power Density
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Yeh, Yung-Sheng, and 葉永盛. "Analysis and Implementation of Single Stage Parallel Boost-Flyback-Flyback Converter." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/15638364135657152615.
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碩士<br>國立交通大學<br>電機學院碩士在職專班電機與控制組<br>98<br>This paper proposes a single-stage boost-flyback-flyback parallel AC/DC converter with single-switch-two-output boost-flyback converter theory. One is the boost-flyback semi-stage that improves power factor and other one is flyback semi-stage that improves the regulation performance and increase efficiency. The proposed converter includes three operation modes- continuous current mode, boundary mode and discontinuous current mode. Various modes would result in various effect on efficiency and power factor under various input voltages and various output loads. The calculation result from MATHCAD and the experimental results demonstrate that the proposed boost-flyback-flyback converter yields higher efficiency and higher power factor than traditional flyback converter.
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Lin, Shu Shi, and 林學世. "A Primary Side Control Flyback Converter." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/83018840086236415065.
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碩士<br>國立臺灣大學<br>電子工程學研究所<br>85<br>Flyback converter has been widely used for low power aplications due to its simple structure and low cost. In conventional flyback converter, opto-coupler and TL431 are used in feedback circuit to achieve electrical isolation. However, it not only increases cost but also adds board size and power consumption. The primary side control flyback converter senses the voltage of auxiliary winding to accomplish output voltage regulation. Because the auxiliary winding and PWM control IC are both in the primary side, the use of expensive components is avoided. Therefore primary side control can improve cost reduction, efficiency improvement and size shrinkage of the flyback converter.
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Shih, Li-Wei, and 施立緯. "Flyback Converter with Current Ripple Reduction." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/47er9a.
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碩士<br>國立臺灣科技大學<br>電機工程系<br>103<br>Employing Power over Ethernet (PoE) technology, power devices (PDs), such as VoIP, security cameras and wireless LAN system node are thus powered over the cable without connecting to an AC source. Therefore, system reliability is increased and a DC-DC converter is built in the power device. Currently, flyback converter with RCD clamped topology is the most commonly used in power device due to it’s simple and low cost for PoE applications. To investigate the pros and cons, a thorough discussion will be provided in the chapter 2.
However, it suffers from the power dissipations in the RCD network. It occupies precious space and degrades the power efficiency. To improve the efficiency, a lossless passive snubber circuit is used instead and a flyback converter with current ripple reduction (FYRR) topology for the PoE applications is proposed in this thesis. In addition to saving the RCD loss, it also has an input current ripple reduction function by utilizing the clamp capacitor and the leakage inductance of the transformer as an embedded notch filter. Consequently, the EMI noise level can be attenuated with smaller EMI filter components to meet the EMI regulation.
In addition to the descriptions of the operation principle, theoretical analysis, and design considerations, two hardware circuits, the flyback with RCD snubber and the FYRR, with 250 kHz, 44-57V input and 12V/24W output specifications are built and tested.
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Li, Heng-Yi, and 李恆毅. "Single-Stage Parallel Boost-Flyback Converter." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/16540659760349787865.
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博士<br>國立交通大學<br>電控工程研究所<br>98<br>It is known that part of the power is repeatedly processed or recycled in the conventional single-stage (S2) and two-stage AC/DC converters. Therefore, a novel S2 scheme is presented based on the parallel power factor correction (PPFC). In the scheme, the boost-flyback semi-stage containing boost cell and flyback cell is used to generate two energy processing path. The main input power flow stream is processed only by flyback cell and output to load directly. And the remaining input power stream is stored in bulk capacitor by boost cell and then transferred by DC/DC semi-stage to output for regulating output power. Theoretical analysis shows that as the boost cell and flyback cell operate in DCM and duty ratio and switching frequency are kept constant, using smaller boost inductor can result in higher power factor. Since most power is processed only once, the power conversion efficiency is improved and the current stress of control switch is reduced. The scheme can also be applied to other conversion circuits by replacing flyback cell and DC/DC semi-stage with other topology.
Taking the parallel boost-flyback-flyback converter as an example, the operation modes and average switching period signals are analyzed, the key parameters of power distribution and bulk capacitor voltage, design equations, and design procedure are also presented. By follow-ing the procedure, an 80 W universal prototype has been built and tested. The experimental results show that at the worst condition of operation range the measured line harmonic current complies with the IEC61000-3-2 class D limits, the maximum bulk capacitor voltage is about 415.4 V, and the maximum efficiency is about 85.8%.
It can be seen from the converter analysis, there are two operation modes in half line cycle and the duty ratio varied with line phase to keep output constant in one mode. The small sig-nal transfer function of the converter with variable duty ratio cannot be validated with con-ventional frequency response measurement. Hence, the small-signal models of operation modes are built and the compensator design at the boundary of modes is presented, the dy-namic response has small steady state error, fast rise time, and heavily damping within opera-tion range. Finally, the dynamic model and designed compensator of parallel converter are verified in time domain by simulation and experiment.
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JING-JYUAN, CHIANG, and 江靜娟. "Study and Implementation of Flyback Converter." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/09262341035472929157.
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碩士<br>東南科技大學<br>電機工程研究所<br>97<br>本論文針對返馳式轉換器做分析研討，深入針對不連續的傳導模式
(DCM)及連續倒通模式(CCM)於返馳式轉換器裡運作方式進行探討。文中分
別針對不連續的傳導模式和連續倒通模式的電路分析和性能評價。又針對
選擇零件和變壓器設計的選用及設計詳細描述。
最後，提出一輸出100 W 返馳式轉換器運作於不連續導通模式和連續導
通模式的設計實例，實驗結果是符合設計。
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Lin, Shu-Shi, and 林學世. "A Primary Side Control Flyback Converter." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/71325325200093371692.
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碩士<br>國立臺灣大學<br>電子工程學研究所<br>92<br>For low power supply applications, flyback converter has been adopted widely because of its simple structure and low cost. In traditional flyback converter, feedback circuit is typically done with the assistance of expensive opto-coupler and TL431, to preserve electrical isolation. However it is not only increases cost but also adds size and power consumption. The primary side control flyback converter senses the voltage of auxiliary winding to regulate output voltage. It can void using expensive element of opto-coupler and TL431. Therefore primary side control flyback converter reduces the device cost and the size, and improve the efficiency of the power supply.
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Chuang, Fu-Yuan, and 莊富元. "Developments and Applications of Flyback Converter." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/35055178583576192902.
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碩士<br>國立高雄第一科技大學<br>電子工程所IC設計及綠色能源產業研發碩士專班<br>99<br>The purpose of this thesis is to study flyback converter and then, applying this type of converter to design dc/dc converter, dc power supply, power factor corrector (PFC), and engine electronic igniter. In dc/dc converter application, a 100W flyback-type converter is implemented with closed-loop control to regulate output voltage. To serve as a dc power supply, flyback-type converter is adopted and designed to provide four different voltages for low power applications. Based on one-cycle control, the flyback-type converter is also developed for power factor correcting. In this thesis an 80W one-cycle-controlled PFC prototype is built to drive LED arrays. For vehicle application, the structure of flyback-type converter is modified and applied to engine electronic igniter, which can promote combustion efficiency, save oil consumption, fuel efficiency and CO2 reduction. The control core of the electronic igniter is implemented on a single chip to lower discrete component count, reduce volume, and increase control flexibility. Hardware waveforms and practical measurements have verified the feasibilities and functionalities of the all designed converters in this thesis.
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LIOU, GUAN-TING, and 劉冠廷. "Development of Multi-Output Flyback Converter." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/7j6rjy.
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碩士<br>崑山科技大學<br>電子工程研究所<br>107<br>Each consumer electronics may require different power voltage level.Hence, the main purpose of this thesis is to complete the development of a sinle-input multi-output flyback DC-to-DC converter. The design of a voltage input range is DC power supply 9V~36V, total power 30W, switching frequency 60kHz~65kHz, output 5V, 12V and 15V. The power converter, and a detailed design description of the transformer, as well as a series of output experiments, it can be widely used in different power voltage level supply of consumer electronics.
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Yu, Fu-Kung, and 余富恭. "Implementation of an Active Clamp Flyback Converter." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/18992585177428643031.
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碩士<br>國立雲林科技大學<br>電機工程系碩士班<br>92<br>The high voltage stress of power semiconductors caused by the parasitic element of the transformer and the power switch in high frequency switching mode power supply when power switch is turn off . RCD clamped circuit is used to limit the switch voltage surge. However, the energy stored in the transformer leakage inductance will be dissipated in the clamp resister. It will reduce the efficiency of converter. In this paper an active clamp circuit technology is used to reduce the peak voltage stress across the power switch. The transformer leakage inductance and the equivalent capacitor including the clamp capacitor and the parasitic element across power switch are used to achieve the Zero Voltage Switching for power switch. The active clamp scheme can reduce switching loss at power switch, reduce EMI, and increase power converter efficiency.
The operation principle of active clamped flyback converter is presented. The experimental results are discussed is this paper.
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Que, Bai-song, and 闕百淞. "Active-Clamp Flyback Converter with Synchronous Rectification." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/79054355945786810516.
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碩士<br>國立臺灣科技大學<br>電子工程系<br>101<br>This thesis focuses on the study and implementation of an active-clamp flyback converter, and compare it to a conventional flyback converter. The active-clamp flyback converter uses a capacitor to absorb the leakage inductor energy of the transformer and eliminate the voltage spike when the switch is turned off. Also the zero-voltage switching is achieved by the resonant tank to raise the conversion efficiency. The discussed active-clamp flyback converter is operated under CCM at light load. Therefore, the synchronous rectification is easier to fulfill. The operating principles are discussed. A prototype converter with an input AC voltage range from 90 Vac to 264 Vac and an output of 19 V/45 W is implemented and tested. The efficiency at rated load is 89.5%.
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Yeh, Soung-Poul, and 葉松柏. "Flyback Converter with Current Ripple Reduction (FYRR)." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/30280155530000096555.
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碩士<br>國立臺灣科技大學<br>電機工程系<br>98<br>Flyback converter with current ripple reduction (FYRR) is proposed and investigated in this thesis. The input current ripple reduction is achieved by utilizing the clamp capacitor and the leakage inductances of the transformer. Therefore, the EMI noise caused by the pulsating input current waveform can be reduced.
Moreover, the EMI noise level can be further reduced by utilizing the clamp capacitor and the leakage inductance of the transformer as an embedded notch filter.
To further improve the efficiency of the FYRR by utilizing a high-voltage switch cell, two-switch flyback converter with current ripple reduction (2SFYRR) is also proposed and investigated in this thesis.
To demonstrate their feasibility, the operation principles as well as the experimental results with 150 kHz, 40-60V input and 5V/20A output are described in this thesis.
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Chao, Kuang-Yuen, and 趙光遠. "Study of flyback converter with Uninterruptible Feature." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/45833999362176697419.
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碩士<br>國立臺灣海洋大學<br>電機工程學系<br>96<br>The purpose of this thesis cites a dc to dc converter with uninterruptible which consists of flyback converter and a buck battery charger. Battery charger and main power uses a transformer to isolate, and it can uses different agist winding to adjust the voltage.It uses IsSpice simulation to verify this result.
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Chen, Ming-Ren, and 陳明仁. "Interleaved Flyback Converter with Zero-Voltage-Transition." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/62814697601088122192.
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碩士<br>國立東華大學<br>電機工程學系<br>97<br>This paper proposes a novel interleaved flyback converter which is composed of two parallel-operated basic flyback converters in addition to an auxiliary inductor and two snubber circuits.
This circuit is able to transfer higher power at a much higher efficiency than conventional flyback converters. There are two efficiency boosting features in this proposed circuit. First, both the active power switches are zero- voltage-switched and therefore the switching losses are reduced. Second, the reverse recovery losss on the rectifying diodes are reduced. This is because of the auxiliary inductor which makes the diode currents smoothly ramp down to zero instead of abruptly turn off.
The two basic flyback converters are identical, which makes operation analysis and circuit design simpler. A test circuit is built and the experimental result shows satisfactory agreement to the theoretical analysis. The experimental results show that this proposed converter promotes its conversion efficiency up to 91%.
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Ku, Chia-Lun, and 古家綸. "Two-Transformer Active-Clamping Forward-Flyback Converter." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/72789421884909062453.
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碩士<br>國立臺灣科技大學<br>電子工程系<br>103<br>This thesis presents a two-transformer active-clamping forward-flyback converter. The proposed topology is mainly composed of two active-clamping counterparts, but only two switches are required, the cost of the converter are thus reduced. In addition, two switches work on zero-voltage-switching(ZVS) operation such that the converter efficiency is improved. The merits of the proposed topology is that it can separate the volume of the transformer by utilizing two transformers. It is easy to achieve high power density. The operating principles and design considerations of the proposed converter are analyzed and discussed in details.
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Wooding, Gareth. "Mitigation of EMI in a flyback converter." Thesis, 2013. http://hdl.handle.net/10210/8690.
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M.Ing. (Electrical & Electronic Engineering Science)<br>This study investigates the mitigation of conducted electromagnetic interference (EMI) in a flyback DC-DC converter. Without the use of filters, the maximum mitigation of EMI possible without significantly decreasing converter operating efficiency is investigated. The following parameters are found to influence EMI: · Switching speed: Decreasing switching speed (increasing rise and fall times of the MOSFET) effectively reduces both common mode (CM) and differential mode (DM) EMI above a certain frequency. Series gate resistors up to a certain value were found to not increase power dissipated in the MOSFET. Series gate resistors greater than this value, further reduce CM and DM EMI at the cost of larger amounts of power being dissipated in the MOSFET. · Leakage inductance and inter-winding capacitance: The dominant component of the flyback coupled inductor in terms of EMI generation is the inter-winding capacitance. Increasing inter-winding capacitance increases both CM and DM EMI. Reducing inter-winding capacitance increases leakage inductance. Increasing leakage inductance however, results in reduced converter efficiency. Coupled inductor design is therefore a compromise between leakage inductance and inter-winding capacitance. · Layout inductance: Reducing layout inductance in certain parts of the circuit is an effective method for reducing DM EMI. This is shown to also decrease CM EMI but not to the same extent as DM EMI. · Snubbing: Snubbing is shown to effectively reduce both CM and DM EMI by reducing the magnitude of the voltage overshoot and ringing on the drain of the MOSFET. Snubbing however reduces converter efficiency. This study gives important guidelines to the engineering trade-offs in reducing EMI versus efficiency in a flyback converter.
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Chen, Yu-Fang, and 陳郁方. "Cascode Flyback Converter used on Photovoltaic Module." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/73929944795621855452.
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碩士<br>國立成功大學<br>電機工程學系專班<br>95<br>The purpose of this study to design the cascode flyback DC/DC converter is to increase efficiency in power conversion. It is also applied on Maximum Power Point Tracking (MPPT) of photovoltaic to get stable DC power. This study focuses on the least capacity of hardware circuit to produce DC/DC converter, as well as the use of Renesas's M16C series MCU (M30262F4) to control, detect voltage and output current of photovoltaic. The perturbation and observeation method is applied for MPPT, producing 80 kHz PWM signal to control power transistor of cascode flyback DC/DC converter, and enabling photovoltaic to get the max conversion.
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Chiang, Cheng-Han, and 江承翰. "Implementation of Flyback Converter for LED Lighting." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/47239750490493598068.
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碩士<br>國立雲林科技大學<br>電機工程系碩士班<br>101<br>ABSTRACT
Light-Emitting Diodes (LEDs) are no longer confined to use in commercial signage and now moved firmly, and with unquestioned advantages, into the field of commercial and domestic lightning. However, about 20~22% of electric energy in the world is used for lighting. At present, flyback converter has been widely used because of its relative simplicity and excellent performance in power converters.
In this thesis, flyback converter operated in discontinuous conduction mode (DCM) is adopted as an off- line LED driver for applications. This LED driver is suitable for cost sensitive applications due to the minimal component parts and a very simple control circuit. The features consisting of a high performance fixed frequency current mode PWM controller, it offers a cost effective solution with minimal external components, including an oscillator, a temperature compensated reference, high gain error amplifier, current sensing comparator for driving a power MOSFET.
Besides, one voltage and current controller IC which is used in the secondary side for controlling the output DC voltage and output current of LED lightning. It also provides a feedback through an optocoupler to the PWM controller IC in the primary side. The main function of the LED drive circuit is to limit the current regardless if input and output conditions across a range of operating conditions.
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CHOU, KUAN-CHIN, and 周冠志. "Design of Flyback Converter Using Taguchi Method." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/84z74q.
Full textAbstract:
碩士<br>建國科技大學<br>電機工程系暨研究所<br>107<br>This thesis proposes a Taguchi’s orthogonal arrays concept of which the efficiency of the flyback converter can be effectively improved by using a simple orthogonal array experimental design as well as a simplified factor response analysis and referring to small quantity of experimental statistics for further analysis. We expect to use the optimal parameter combination obtained by Taguchi Method for enhancing the efficiency of the flyback converter. That is, the Taguchi Method can be used to help us to understand the effects of the design factors including the switching frequency(fs), duty cycle(Duty) and boundary current(Iob) of a flyback converter. In this thesis, we fabricate one flyback converter with input of DC 155V and output of DC 12V/84W based on the best parameter combinations. Using orthogonal arrays L9, the optimal parameter combination is fs:50kHz, Duty:0.3 and Iob:4A. Then, the efficiency test of the flyback converter has been done. The result predicted with Taguchi Method is identical to what we test.
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Shih, An-Ti, and 石安迪. "Mixed-Equalization Circuit Using Bi-Directional Flyback Converter." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/49212776296773655614.
Full textAbstract:
碩士<br>國立臺灣科技大學<br>電子工程系<br>104<br>In this thesis a mixed-equalization circuit for series-connected battery packs is proposed, which applies a bi-directional flyback converter to balance six battery packs. The four cells inside each battery pack are balanced by passive balance method. Each side of the flyback converter is connected with three battery packs. The energy is transferred directly from the highest battery pack to the lowest one through the converter. This proposed scheme aims to reduce the power dissipation during the multiple transfer processes and the time required for balancing.
In this thesis, a 16-bit digital signal controller, dsPIC30F4011 from Microchip, is applied to act as the control kernel which communicates with the BMS IC using sequential peripheral interface (SPI), monitors all the batteries voltage and decides which two battery packs to be connected to each side of the flyback converter for proceeding balancing process. A battery pack consists of 24 series-connected Li-ion battery cells is used for the experiments to verify this proposed circuit topology and control scheme.
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Chen, Jia-ming, and 陳加明. "Magnetic Amplifier Voltage Regulation Technique for Flyback Converter." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/d6hq74.
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碩士<br>國立臺灣科技大學<br>電子工程系<br>94<br>In the power supply system, multi-output is always one of the basic requirement for the user. In earlier times, it did not request all the outputs of a power supply system with an excellent voltage regulation in the application. Basically one of the outputs is chosen as feedback control for stabilizing the system. As for the other outputs, their output voltages were obtained by varying the transformer turns ratio. This kind of power system design is only used for the application which doesn’t request highly accurate voltage regulation.
For improving the voltage regulation, the MagAmp used as post regulation has become the best solution. The MagAmp was popularly used in the forward multi-output system in the past. Since each output must have a bleed resistor to ensure the instability in the light load condition, it then causes dissipation on the resistor. In order to achieve a low cost and an excellent voltage regulation, it is the best choice to add a MagAmp used as post regulation for the flyback converter. The ”time share” technique uses MagAmp in flyback converter can provide tightly regulated outputs, and a multi-output power system of 100W flyback circuits is examined. This proposed converter can totally replace the traditional forward converter, and it also can archive of low cost and the stable output voltage for each output.
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Hu, Chia-Chien, and 胡家傑. "Flyback Converter For Light Emitting Diode Driver Circuit." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/734np8.
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碩士<br>崑山科技大學<br>電機工程研究所<br>97<br>High power white light emitting diode (LED) has attracted a lot of attention from both industry and academia for its high efficacy, simple to drive, environmentally friendly, and long lifespan. It becomes possible applications to replace the incandescent bulbs and fluorescent lamps in residential, industry and commercial lighting. The realization of this new lighting source requires both tight LED voltage regulation and high power factor as well. This thesis proposed a flyback converter for the LED lighting applications and input power factor correction. A PI controller has been inserted in the voltage loop providing sufficient bandwidth and stability margin. The converter is controlled with voltage mode PWM and run in discontinuous conduction mode (DCM) so that the inductor current follows the rectified input voltage, resulting in high power factor. A prototype topology of flyback converter for LED driver circuit is designed for an 18W LED lighting source is constructed and tested to verify the theoretical predictions. The measured performance of the LED lighting fixture can achieve a high power factor greater than 0.998 and a low total harmonic distortion less than 5.0%. Experimental results show the functionality of the overall system and prove it to be an effective solution for the new lighting applications.
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Chung, Ching-Hsian, and 張景軒. "100W Flyback/Forward Converter Realization and Experiment Analysis." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/32664940073891611224.
Full textAbstract:
碩士<br>國立交通大學<br>機械工程學系<br>98<br>This article proposes how to realize 100W flyback and forward converter from mathematical theory, design components to accomplish the products. And then we are going to analysis some experimental results, likes power efficiency, dynamic load characteristics, etc. Chapter 1, we would introduce the basic operation principle of the isolated switched-mode power supplies (flyback and forward converter), and its corresponding circuit’s state and mathematical models. Chapter 2, we are going to introduce how to design the converter’s passive components and to chose a proper active component. After that, we can start to design the feedback network components to make system stable and response rapidly. Chapter 3 will analysis some experimental results. And Chapter 4 is our conclusions.
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CHU, HUA-HUANG, and 朱華煌. "The Strategy of Electromagnetic Interference for Flyback Converter." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/11502212319053753573.
Full textAbstract:
碩士<br>逢甲大學<br>資訊電機工程碩士在職專班<br>98<br>The main purpose of this thesis is to design a Flyback power converter by using a new type of PWM IC. Since the way to solve the issue of EMI is complicated and tedious, it is a great challenge to design the electronic instruments and electronic communication device. Due to the highly developed technology of semiconductor, the new type PWM IC possesses a jitter frequency technique. Comparing with the traditional methods such as the insertion of noise-filter, the jitter frequency technique solves problem directly from the noise source. In other words, by dispensing the spectrum energy, the EMI can be dramatically reduced so that the size of converter can be more compact compared with that of the traditional one.
The principle of Flyback converter will be firstly discussed in this thesis. Later, the circuit designs for EMI filter with the jitter frequency technique of converter and the traditional converter will be addressed and implemented. Finally, the experiential results of a 60 watts converter with the jitter frequency technique and the traditional method will be presented and demonstrated.
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Huang, Shun-Liang, and 黃順良. "High Power Factor Flyback Converter for LED Lighting." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/60035782630559120896.
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碩士<br>國立雲林科技大學<br>電機工程系碩士班<br>97<br>This thesis presents the Flyback converter with power factor correction (PFC) for light emitter diode (LED). The stricter requirements for harmonic regulations are necessary around the world in the recent years. More and more academics determined themselves on the study of PFC which is well connected with technology and all electronic appliances. The circuit structure in the thesis is suitable to low power applications by using Flyback converter due to its simple structure and low cost. LED is very important for the oncoming lighting system and LCD screen. The circuit control including constant voltage and constant current loop is able to prevent the damage which is caused due LED is too sensitive to change of voltage and current. Besides, the circuit control also can make LED with the equal brightness. The aforesaid mentions will be verified by the conclusion of the experimental results.
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Tsui, Cheng-Wen, and 崔正文. "Valley-Detection Technique for Quasi-Resonance Flyback Converter." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/00623798584041392852.
Full textAbstract:
碩士<br>大同大學<br>電機工程學系(所)<br>103<br>In this thesis, a valley detection technique applied for quasi-resonant flyback converter is proposed, which not only can set a reasonable switching timing according to various loading conditions, but also improve the switching losses resulted from the increased switching frequency at light load. Comparing with the traditional hard-switching under current mode control has better conversion efficiency. In addition, a quasi-resonant flyback converter is implemented by using the proposed valley detection technique, whose specifications including output power of 20W, input voltage ranges from 90-265Vac, and output voltage of 12Vdc. Finally, the measured four-point average conversion efficiency can achieve 80% under 25%, 50%, 75% and 100% load in full region of the input voltage, as well as meet the specification requirement of the DoE level V.
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Tsai, Hsing-Wei, and 蔡幸葦. "A Quasi-Resonant Flyback Converter with Synchronous Rectification." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/72851151292138833184.
Full textAbstract:
碩士<br>國立臺灣科技大學<br>電子工程系<br>103<br>The purpose of this thesis is to study and realize an auxiliary power which is based on quasi-resonant flyback topology for industrial usage. In order to promote the overall efficiency, synchronous rectification method is applied at the secondary side. Different from conventional flyback converters, the switching-on timing is controlled at when valley voltage occurs on the switching device. Not only the efficiency can be obviously improved, but also the temperature inside the machine can be lower. The leakage inductance of the transformer and the parasitic capacitance on the MOSFET are used for resonance, and therefore no extra circuit element is added. Synchronous rectifier is used to replace the secondary diode to reduce the conduction loss. The achievement of the thesis not only can be successfully applied on industrial products but also promotes the efficiency and increase the practicability.
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Chang, Shih-Ying, and 張仕穎. "Dual-output Flyback Converter for Photovoltaic Generation Application." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/44328126836215184099.
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碩士<br>國立彰化師範大學<br>電機工程學系<br>104<br>In this thesis, dual-output flyback converter for photovoltaic generation application is proposed to overcome the failure in complete use of solar energy issues of building-block photovoltaic system. This system including two modules, those are the double-output photovoltaic generation module and multilevel inverter module.
The double-output photovoltaic generation modules can work in parallel-connected to provide a stable DC power source. In addition, the photovoltaic generation modules can also work in series-connected with a multilevel inverter module to provide a stable AC power source. By using the multilevel inverter module, the partial shading effect can be resolved.
When the double-output photovoltaic generation module does not provide power to the multilevel inverter module, the switch can be used, thereby providing energy to the battery, improve the utilization of photovoltaic generation modules. Finally, a 360W prototype has validated and useful, experimental results show that the system has availability.
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Lin, Wei-Shiang, and 林煒翔. "Flyback Converter for Low Power LED Lighting Applications." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/68674151606894577308.
Full textAbstract:
碩士<br>國立雲林科技大學<br>電機工程系碩士班<br>101<br>ABSTRACT
This thesis presents a Flyback converter for lighting emitter diode (LED) applications. Instead of traditional light up circuit and Cold Cathode Fluorescent Lamp (CCFL), the LED is popular in lighting industry applications. Flyback converter with the low cost and simple structure is adopted to drive the LED lamp. The LED constant voltage and constant current loop are used to prevent the LED damage clue to the voltage and current variation. Finally, according to the analysis and design consideration in this paper, a convertor with P_o=12W, v_ac=85~265V, v_o=31V was implemented to verify the performance of the proposed converter.
Keywords：Flyback converter, Constant voltage control, Constant current control.
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Wang, Wei-Ming, and 王暐鳴. "Design and Implementation of Active-Clamped Flyback Converter." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/83u3x6.
Full textAbstract:
碩士<br>國立臺灣科技大學<br>電子工程系<br>107<br>The purpose of this thesis is to present the operation principle of Active Clamp-Flyback converter. By the design rule in the content, we can make a circuit, and check the availability by simulation and experimental result. For the expectation of high frequency operation in the future, we use GaN device rather than using traditional Silicon device for all the switches in the circuit. Auxiliary switch and clamp capacitor in the circuit can recycle the energy in the leakage inductor of transformer. In this way, we can eliminate the voltage spike appear in the primary side of transformer and achieve Zero-Voltage-Switching for the main switch so as to reduce the voltage stress on the main switch.
After the introduction of operating principle and design rule, we made an active clamp flyback circuit whose switching frequency is 300kHz, input voltage is 127V to 380V, and output specification is 19V/65W. By the experimental result, we can prove the performance of the circuit.
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Yan, Yeong-Chang, and 顏永昌. "Systematic Analysis and Design of Dual-Switch Flyback Converter." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/52495757111396327206.
Full textAbstract:
博士<br>國立臺灣科技大學<br>電子工程系<br>104<br>Like single-switch architecture, the dual-switch flyback converter also has the same characteristics, including simple circuit topology, low cost, electrical isolation and multiple outputs. Moreover, due to the dual-switch flyback converter providing an additional current return path, it will reduce the ring effect and enhance the circuit conversion efficiency, and it is suited to use for the low-voltage and low-cost power switches. Therefore, the dual-switch topology is also widely used.
This dissertation presents the circuit analysis and design considerations for the dual-switch flyback converter. The operation modes are individually analyzed and the corresponding dynamic equations are presented accordingly. Also, the design criteria for key components are derived. Good agreement can be obtained among the Pspice simulation, the experimental results and the theoretical analysis. The analytic equations are valid not only for continuous-conduction-mode condition, but also for critical mode operation, which meet the design specifications.
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Lin, Po-Han, and 林柏翰. "Matrix Style DPWM LED Driver with Flyback Buck Converter." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/84684305402986584586.
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碩士<br>國立臺灣科技大學<br>電子工程系<br>105<br>In recent years, light-emitting diode (LED) has been widely applied to various circuits, such as liquid-crystal display, lighting, backlight source of large scanning boards display, etc. As LED application becomes more popular, it needs to be further adapted in order to better fit the market needs. For circuit simplification, chip area reduction and cost down, both the AC/DC controller and the LED driver will be designed. The supply voltages for LED strings and the corresponding driver are generated from the AC/DC converter with flyback control. Furthermore, the operation of Digital Pulse Width Modulation (DPWM) for LED dimming will be modified and enhanced to reduce flicker and lower the load current variation from the power supply. A temperature-compensated bandgap circuit is utilized to offer constant driving currents for LED strings to diminish color cast. Also, a high precision common centroid layout pattern is adopted to reduce the current mismatch among LED strings.
The flyback converter with auto reset dropout voltage is designed in a TSMC 0.5μm 2P3M COMS 800V ultra-high voltage process. The chip area is 2.0433.057 mm2. The LED driver with enhanced digital pulse width modulation is fabricated in a TSMC 0.25μm 1P3M COMS 60V high voltage process. The chip area is 1.76*1.37mm2. With simulation and measured results, both chips are turned out to function as expected.
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Cheng, Yu-nan, and 鄭玉南. "Study on the Snubber Circuits for a Flyback Converter." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/qtkztw.
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碩士<br>國立臺灣科技大學<br>電子工程系<br>94<br>This thesis aims at the analysis of an active-clamping flyback converter. The comparisons between the active-clamping flyback converter and the conventional flyback converters adopting passive snubbers are made. The resonant tank of the active-clamping flyback converter consists of the leakage inductance of the transformer and the parasitic capacitance of the switch. The zero-voltage swtiching can be achieved by adequately design the circuit parameters. The conversion efficiency can thus be raised and the voltage spike on the switch can be reduced. Also the loss distribution is derived. An active-clamping flyback converter with an output rating of 24V/8A/200W is implemented in the lab. The experimental results are closely conformed to the theoretical analysis and the simulations.
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Liau, Ching-bin, and 廖慶斌. "An Active-Clamping ZVS Flyback Converter with Integrated Transformer." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/97x3cc.
Full textAbstract:
碩士<br>國立臺灣科技大學<br>電子工程系<br>102<br>Abstract
This thesis studies an active-clamping flyback converter using a integrated transformer. The proposed converter is composed of two active-clamping flyback converter. load current between two secondaries can be equally shared so that the rectifier diode conduction loss can be reduced. Otherwise, the main switch of any converter serves as auxiliary switch for the other one, so that only two switches are required and both can achieve zero-voltage-switching (ZVS) operation. The transformers of converter are integrated into one magnetic core, therefore, the volume and copper loss of transformer can be reduced. Detailed analysis and design of the integrated magnetic active-clamping flyback converter are described. POWERSIM simulation are shown for verification. Experimental results are discussed for a prototype converter with AC input voltage from 380 V, an output voltage of 19 V and an output current of 10 A, operating at a switching frequency of 100 kHz.
Keywords: Active clamping, flyback converter, integrated magnetic, zero-voltage-switching
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LIANG, CHI HO, and 梁期合. "Flyback PFC Converter with Low-Frequency Voltage Ripple Reduction." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/xgh9vy.
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碩士<br>國立臺灣科技大學<br>電子工程系<br>102<br>This thesis studied two circuit topologies to reduce low-frequency output ripple voltage based on flyback power factor corrector (PFC). In the first topology, a reverse ripple voltage is produced by an Inverse-Buck convertor cascode at the output side to cancel the ripple. In the other topology, a bidirectional buck-boost converter is parallel-connected at the output to absorb/ supply power and thus reduce the ripple.
Due to ripple reduction, small output capacitance can be used. Therefore, electrolytic capacitor is replaced by solid-state capacitor in the prototype converter to prolong the lifetime. In this thesis, the operating principles and design considerations for the two circuit topologies are analyzed and discussed. 36 V/ 60 W laboratory prototypes are built and tested to verify the theoretical analysis.
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Liu, Tsung-Yen, and 劉宗延. "Burst Mode Circuit Design for Quasi Resonant Flyback Converter." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/67858595527396548804.
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碩士<br>國立臺灣大學<br>電子工程學研究所<br>95<br>Reducing standby power of the power supply or converter is more and more important, because of emphasizing power management and energy conservation today. The burst mode circuit in this thesis is applied to the quasi-resonant mode flyback converter to reduce switching loss and conduction loss under very light load and no load.
The burst mode circuit in this thesis is actually applied to green mode operation of the quasi-resonant mode flyback converter. The basic circuit architecture is from the relaxation oscillator. The manufacturing technology of the burst mode circuit is 0.5μm、2P3M CMOS process. The designed functions of the burst mode circuit are verified by the experimental result.
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Huang, Guan-Rong, and 黃冠榮. "An Improved Over-load Protection Method in Flyback Converter." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/27128808903668998323.
Full textAbstract:
碩士<br>國立彰化師範大學<br>電機工程學系<br>102<br>The traditional Flyback converter nature is a constant power output, If the output load reaches a limit point, the output voltage would descend and output current would ascend until the output voltage drop to zero, then the output current will be infinite that will cause burning problem.
The proposed technology is using variable level for the reference by means of the over-load trigger point. If the circuit is normal operating the trigger point would be fixed, but on the contrary the circuit is abnormal operating the trigger point would be descended by reducing duty cycle to limit the output current on secondary.
In this thesis, the operating principle and mathematical model aim at the novel methods. Then, the value of each component is well designed to satisfy the electrical specification. After determining the value component, the theoretical analysis is verified by Pspice simulations and the experimental results.
The experimental results reveal that when the input voltage Vin = 17 V~34 V, the output voltage VO = 5 V, the output power PO = 5 W, the switching frequency fsw 550 kHz, operating in DCM, and over load setting point at 1.28 A. the proposed novel over-load control methods can validate in a wide input voltage range and output short conditions, which also has good current accuracy about 2% and reduction power dissipation about 68%.
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TWU, JHANG-YI, and 涂正誼. "Low Input Current Ripple Asymmetrical Half Bridge Flyback Converter." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/24607791252339196510.
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碩士<br>國立臺灣科技大學<br>電機工程系<br>102<br>Asymmetrical half-bridge flyback converter (AHB-flyback) is attractive because of its simplicity of secondary side configuration, and low voltage stress. It can achieve high efficiency by using soft switching techniques, such as the zero-voltage switching (ZVS) of primary power switches and the zero-current switching (ZCS) of output rectifiers. These characteristics make it suitable for high frequency and high input voltage power conversion applications. However, this converter has pulsating input current resulting in generating high di/dt noise. To reduce the pulsating input current ripple, an Input Current Ripple Reduction Asymmetrical Half Bridge flyback converter (RR-AHB-flyback) is proposed in this thesis.
In addition to inheriting the advantages of AHB-flyback converter, RR-AHB-flyback has significantly reduces input current ripple due to its built-in current ripple cancellation mechanism. Furthermore, the coupled inductor is used to achieve high power density and wide ZVS range.
Operation principles and circuit design are shown in this thesis. Both of AHB-flyback and RR-AHB-flyback are experimented under 100 kHz, 300-400 V input and 24V/10A output to demonstrate its feasibility.
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Wei, Sian-You, and 魏先佑. "Multiple Winding Bidirectional Flyback Converter Used in Solar System." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/46719411036852548035.
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碩士<br>國立雲林科技大學<br>電機工程系碩士班<br>99<br>This thesis presented a multiple-winding bidirectional flyback converter which is used in the solar power system. In the preceding stage of the system, it was a bidirectional flyback charge/discharge circuit combined with the maximum-power-point tracking circuit of the solar energy. In the succeeding stage, it was the multilevel inverter system. The two stages were integrated to complete the overall system frame.
The multiple-winding bidirectional flyback charge/discharge circuit is combined with the maximum-power-point tracking circuit of the solar energy. In the normal operation of solar panels, the energy can be charged to the battery module. When one or more solar panels are out of order, the battery module supplies the energy to the inverter through the bidirectional flyback converter without affecting the operation of the inverter.
Generally, one solar energy maximum-power-point tracking circuit is with one battery module. So more tracking circuits need more battery modules. However, for the multiple-winding bidirectional flyback converter presented in this thesis, it uses only one battery module and can be applied to the multiple solar energy maximum-power-point tracking circuits. As for the number of battery in one module, it can be set according to different load requirement. Furthermore, for the charge way of battery, the interleaved energy charge method used by the bidirectional flyback converter is proposed in this thesis.
All the above mentioned functions are realized with TI Company’s TMS320LF2407A digit signal processor to integrate the complete system.
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Lin, Chih-Hsien, and 林志賢. "The Analysis, Simulation and Implementation of a Flyback Converter." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/49598186404029474500.
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碩士<br>逢甲大學<br>資訊電機工程碩士在職專班<br>98<br>Nowadays, the switch power converters have been broadly applied to the areas of computer peripheral, communication equipments, network devices, medical instruments, industrial products and home appliance. Due to the highly developments of the power semiconductors and microcontrollers, the compact, light weight and high efficient electronic devices is the goal of most of the manufactares to persuit and it is no exception for the tendency of power converter development.
The fundamental of switching power converters will firstly be analyzed and designed in this thesis. Later, the power converter will be modellized for the IsSpice simulation software package to simulate. The open and close loop controls of the power converter will be compared each other. Based on the simulation results, a power converter will be realized and implemented in this thesis. The experimental results show the verification for the design and implementation of the power converter. Finally, this thesis will demonstrate a modellized power converter system and realized prototype of the flyback converter.
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Huang, Chien-Ming, and 黃建銘. "Valley-Fill Filter Flyback Converter with Variable Frequency Control." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/11874433101784943322.
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碩士<br>國立成功大學<br>電機工程學系碩博士班<br>91<br>The conventional diode-capacitor rectifier is used in front end of electronic equipment to provide the dc bus voltage source. The input current contains high current harmonics and causes several problems such as low power factor, voltage distortion, and electromagnetic interference. The valley-fill filter functions as a passive power factor corrector but large ripple voltage will be presented in the dc bus. Usually, a postregulator is used to supply a regulated dc source for the load, but large low-frequency voltage ripple still exist in the load. This thesis proposes a valley-fill filter variable frequency controlled flyback converter to reduce the low-frequency ripple. Theoretical analysis and experimental results show that the low-frequency ripple can be suppressed within ±0.3% and input current harmonics can meet with IEC 1000-3-2 Class A requirement.
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Lin, Zi-Sheng, and 林子勝. "The Study of Solar Energy Half-Bridge Flyback Converter." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/42448598511299391006.
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碩士<br>國立勤益科技大學<br>電子工程系<br>102<br>The thesis aims at design of solar converters, and it makes use of PWM to conduct control of output voltage and electric current. In chip, it adopts HT66F40 of Holtek and TL494 to control signal. With modulation of signal, it sets required frequency and duty cycle, and it integrates dual signal with half-bridge electric circuits to improve bearing load wattage of the output terminal. Dual signal carries on control of signal by one crystal conduction with one crystal cutoff to upgrade output bearing load wattage. It integrates half-bridge electric circuits with flyback electric circuits to improve efficiency of converters, and converters of flyback electric circuits are bipolar mode with winding both sides of the coil. Input and output electric currents have properties of continuous and discontinuous conduction, and functions of effectively improving signal isolation and anti-electromagnetic interference. Back-end collocating with rising electric circuits supplies output terminal stable electric circuit output. In this research, the solar panels got electric energy after half-bridge flyback converter adjustments to lead-acid batteries charge. The advantages of converters are as following, higher power, high efficiency, small volume of electric currents, easy-processing signal, and lower costs.
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Lin, Hui-Chang, and 林輝菖. "High Efficiency Quasi-Fixed-Frequency Quasi-Resonant Flyback Converter." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/62019999127108828186.
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碩士<br>國立臺灣科技大學<br>電子工程系<br>103<br>Conventionally, Quasi-Resonant (QR) flyback converter is required to turn on the active switch when the first voltage valley is detected. Therefore, the advantages of soft-switching can be achieved. However, for light-load output and high-voltage input, the duty cycle would be very small, and magnetizing current is also small. After the switch is turned off, the switch voltage could resonate to valley in very short time; therefore, the switch should be turned on again. The increased switching frequency results in higher switching loss and impairs the efficiency. The purpose of this thesis is to propose a high-efficiency QR-flyback converter. By the proposed “Quasi-Fixed-Frequency” algorithm to maintain the frequency within a small range, but still turns on the power switch at voltage-valley. Therefore, the characteristics of low switching-loss can be attained.
The prototype circuit in this thesis is a 65-W Quasi-Fixed-Frequency QR-flyback circuit, the control circuit is implemented by the IC UCC1803, which is the power-efficient version of the commonly used pulse-width-modulation (PWM) IC UC3843. In addition, a specific valley detection circuit is added on to fulfill the control task. The experimental results ascertain that this proposed circuit can improve efficiency during light-load and high-voltage input. Even at high-voltage input and heavy load, the efficiency is approaching 95%.
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Lin, Kuan-Yu, and 林冠宇. "Analog Compensator Design for aMulti-Mode Controlled Flyback Converter." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/32482836451879765434.
Full textAbstract:
碩士<br>國立臺灣大學<br>電機工程學研究所<br>103<br>Flyback converter configuration has been a popular choice for many power electronic applications for many years. Recently, a so-called multi-mode control (MMC) scheme has been reported to improve the overall performances for applications requiring wide line voltage and wide load range such as the computer power systems. The idea of MMC is to provide different control strategies according to the load level. When the load is heavy, quasi-resonant (QR) control mode is used. When the load is reduced, a discontinuous conduction mode (DCM) is used. When the load is very light such as in the computer sleeping mode, frequency-foldback mode (FFM) is used. This way, the converter overall efficiency can be improved.
In this thesis, the feedback behavior of the MMC flyback converter will be analyzed using the small-signal model. Since one compensator is used for the three different modes of control, an analysis is given for the control loop gain bandwidth and stability margin for each mode. Based on this analysis, a design procedure is developed for the feedback compensator design. Simulations are conducted to verify the theoretical results. The procedure is also extended to the so-called USB-PD (Universal Serial-Bus Power Delivery) power that is an up-and-coming household DC converter application for charging mobile devices. For the USB-PD applications, the converter output voltage contains three different voltage levels. The results obtained from this thesis provide useful information for such applications.