Dissertations / Theses on the topic 'Step it Up'

DC-DC converters are electronic devices used to change DC electrical power efficiently from one voltage level to another. Complex systems like an industrial printer require accurate high voltage levels to let the print head nozzles spit out the ink in the proper way, according to the pattern to be printed. Creadigit, product of System S.p.a, is a high precision printing system used in decorations for ceramic products. It is actually powered by a couple of rack mounted AC-DC converters, which offer simple powering solution at low cost. Nevertheless, the total system efficiency can be sensibly increased with the introduction of a DC-DC Step UP converter in place of the AC-DC supply. This thesis is focused on the analysis, modeling, design and implementation of a Boost converter for such application. One project goal is to provide the converter the ability to digitally adjust the output voltage according to the requirements of each printing head, thus leading to a consistent power saving of the entire system. The work structure is so arranged: first of all, it is explained the architecture of the printing system and the inkjet printing mechanism so as to understand why high voltage supplies are required. Secondly, the power amplifier system is analyzed through simulation in LTSpice environment. During these simulations, there will be an analysis of potential power savings introduced by the adoption of the adjustable DC-DC converter. It follows the Boost converter theory, necessary to understand the operation of the key element of this project. Moreover, a detailed study of the complex world of capacitors is developed. In fact, the output capacitor selection is one of the trickiest part in the design of a switching DC-DC converter. In this thesis, a short theoretical study about EMC in SMPS converters is accompanied by simulations that could anticipate the results of in-field studies. In the end, some results of a first DC-DC converter prototype will be presented.

Among the many renewable energy sources, solar power is becoming one of the quickest to be adopted due to continuous technological progress and reductions in cost. Today's typical photovoltaic modules that are connected together in series and parallel to form strings and sub-arrays. Various distributed photovoltaic architectures are introduced in this thesis and DC-DC converters with maximum power point tracking are also introduced. Partial power processing is a technique to allow only a fraction of the power to be processed by the DC-DC converter, thereby reducing losses and improving efficiency. A new partial power isolated DC-DC converter is proposed in this thesis. The converter features maximum power point tracking and its controller selectively engages the buck portion or the boost portion or both in response to the maximum power point tracking input signal to achieve the desired output voltage and maximum power. With series connected DC-DC converters, each DC-DC converter carries an equal string current and adjusts its output voltage proportional to the available power of the connected photovoltaic module. The proposed topology allows each photovoltaic module to operate at its own maximum power point under varying or mismatched solar irradiance conditions, yet keep the total DC string voltage constant. The proposed circuit is verified using PLECS simulation software. In comparison to the existing circuit with partial power processing method, the proposed circuit overcomes the disadvantage that the output voltage can only be greater than the input voltage. With the two metal oxide semi-conductor field effect transistors added in series with the diodes in the secondary side of the transformer, the new circuit operates at a 100kHZ switching frequency and is able to perform both step up and step down modes with a properly designed control block. As a result, the circuit can convert a voltage from a PV panel that is higher or lower than the output to a regulated DC output voltage.
Applied Science, Faculty of
Engineering, School of (Okanagan)
Graduate

Energy harvesting systems are becoming an increasingly popular area for research as they present themselves as a clean, renewable source of energy. There are currently some key design issues facing the development of these energy harvesting systems. In particular, these harvesters often produce relatively low voltages compared to the requirements of the intended application. For example, scientific apparatus aboard orbital satellites require relatively high voltage levels for operation (kV) but are powered from solar panels providing substantially lower output voltages (24 V). In contrast, for low power energy harvesting, such as micro scale vibration energy harvesters, a harvested voltage level of ≈0.5V is often required to power a low power sensor circuit which requires 2-5V. Voltage multiplication is commonly achieved using charge pump multiplier circuits. However, these circuits are quite limited in both the range of multiplication (per unit area) and the maximum voltage level. This work aims to take advantage of a noticeable gap in the research field and is specifically targeted towards energy harvesting application areas. This thesis presents a comprehensive analysis of novel bi-stable and resonant MEMS voltage step-up converters. The operation is based on isolating the charge of a mechanically variable capacitor and varying the gap between the electrodes by an appropriate method of actuation force. As the electrode gap varies, so does the voltage level across the electrodes. In the case of the bi-stable devices, electrostatic actuation is employed while the resonant devices rely on ambient vibration force. These have been specifically designed for integration with static and vibration energy harvesters respectively. Prototype devices were fabricated using a dicing-free Silicon-on-Insulator (SOI) process developed at the Southampton Nanofabrication Centre. For the bi-stable device, a maximum output voltage of 35.7V was measured, using a 100MΩ load resistance, from a 24V input voltage. Further improvements in the design of the MEMS variable capacitor can be made in order to increase the capacitance level of the devices while reducing the parasitic fringing capacitance. Optimisation of the MEMS device would enable the output to reach a level near the theoretical maximum limit set at 120V.

The energy produced by the flow of water is known as hydropower. It is an easily accessible and available source of energy in large quantity in the form of, rivers, lakes, streams and runoffs around the world. Hydropower is dependent upon hydrological cycle hence; this beneficial characteristic of hydropower makes it a renewable source of energy. Hydropower is free from poisonous emission; therefore, it is considered as a safer and pollution free source of energy. It is usually used to develop electricity from generators. These generators are connected to the hydro turbines by means of shaft. The electricity produced from hydropower is stable and steady because of its higher capacity, thus it can be a suitable source to work as base-load and used to balance the power fluctuations caused by varying loads. The hydropower can also be accommodated with different sources such as solar and wind system. This way of power sharing needs quick regulation as the deviation in the power grid changes rapidly. To fulfil this power demand with higher stability prompted to the development of modern turbines with more efficient, reliable and robust design.   To achieve the above target, it is of prime importance to improve efficiency of hydro turbine. Nevertheless, many methods are in practice for improvement for efficiency of the turbine; though one of the prime elements which influence the turbine efficiency is surface roughness. The effect of surface roughness differs for different turbine components like stay vanes, guide vanes, runner, draft tube and spiral casing.   The main purpose of this thesis is to examine the effect of surface roughness for hydro turbine step-up efficiency. It is based on reduced scale model to prototype conversion method. For this purpose, IEC_62097 has provided an excel sheet as an attachment for calculation. There has been always a need to perform model test, since performing test on the prototype itself is very accurate, and calculations too, do not yield reliable results. Therefore, the model to prototype conversion method is considered a better solution.   A sensitivity analysis is conducted on a Kaplan turbine situated at the Granfors power station located along the Skellefteå river about 30 km from the city of Skellefteå. The results obtained after applying the latest step-up expressions are described and presented. These outcomes have shown significant positive impact on the hydro turbine efficiency improvement, which are presented in graphs.   The most significant variations of step-up efficiency against surface roughness were observed in the runner part of the turbine. This specific characteristic makes it evident that more focus and test should be conducted on this part to improve efficiency.

This thesis deals with the design and realization of a DC/DC converter, which allows power conversion from 10-52 V input voltage to 10-52 V output voltage at a maximum output current of 3 A. The converter can communicate with the superior system via the CAN. In the first chapter I deal with the available integrated circuits of DC/DC converters, from which I choose one for my application. In the second chapter, I propose a block scheme of the converter, which includes the requirements from the assignment as well as my additional ones. In the third chapter I deal with the design of an electronic circuit and with the calculation of control loops. In the fourth chapter I propose firmware for the STM32 MCU, which controls the device and communicates with the superior system. In the last chapter the DC/DC converter is tested.

En aquesta tesis, es proposarà, com a solució per al disseny d’etapes d’elevat guany en aplicacions fotovoltaiques, la connexió en cascada d’elements canònics per al processat de potència basats en el convertidor elevador boost treballant sota un control en mode lliscant. Els tres elements canònics per al processat de potència són el transformador de corrent continu (CC), el girador de CC i el Loss-Free Resistor (LFR) o resistor lliure de pèrdues. La connexió en cascada de dos convertidors elevadors s’ha realitzat mitjançant diferents enfocs: dos elements canònics idèntics, dos elements canònics diferents i també mitjançant una única superfície de lliscament per controlar els dos convertidors. Les diferents connexions s’han comparat en termes de prestacions dinàmiques, estabilitat y temps d’establiment. Es podrà veure que la connexió en cascada de dos LFR és la millor opció per les aplicacions citades en termes de prestacions dinàmiques i estabilitat. La connexió en cascada de dos LFR s’aplicarà per la implementació d’una etapa d’adaptació d’impedàncies entre un generador fotovoltaic i un bus de tensió continua de 380 V. Per fer-ho s’utilitzarà un sistema MPPT basat en un algoritme de control extremal. Es modelarà la dinàmica ideal en mode lliscant d’ordre reduït a partir del model complet commutat tenint en compte les restriccions del mode lliscant, la característica no lineal del generador fotovoltaic i la dinàmica del control MPPT. A més a més, la connexió en cascada de dos LFR s’utilitzarà per inyectar la potència provinent d’un generador PV a una xarxa de corrent altern . A continuació, es durà a terme una comparació entre la connexió en cascada de dos LFR i dos convertidors amb guany elevat: el convertidor Z-source i un convertidor basat amb inductors acoblats. Aquests convertidors s’analitzaran per tal d’identificar els avantatges i els desavantatges de cada topologia en front a la connexió en cascada de dos LFR. La comparació es farà en termes de volum, nombre de components, prestacions dinàmiques, estabilitat i rendiment. Finalment, els dos LFR connectats en cascada s’utilitzaran per dissenyar una nanoxarxa formada per n LFR connectats en paral•lel que actuaran com etapa adaptadora entre n generadors fotovoltaics i un bus de CC de 380 V. Cada generador fotovoltaic es connectarà al bus de CC utilitzant dos LFR en cascada de forma que els n sistemes tindran els seus ports de sortida connectats en paral•lel. A més a més, es connectarà una bateria al sistema a través d’un convertidor bidireccional que serà l’encarregat de regular la tensió del bus de CC de la nanoxarxa. En el marc d’aquesta tesis s’han implementat diferents prototipus experimentals per tal de validar els anàlisis teòrics i les simulacions numèriques efectuades.
En esta tesis, se propondrá, como solución para el diseño de etapas de elevada ganancia en aplicaciones fotovoltaicas, la conexión en cascada de elementos canónicos para el procesado de potencia basados en el convertidor elevador boost trabajando bajo un control en modo deslizante. Los tres elementos canónicos para el procesado de potencia son el transformador de corriente continua (CC), el girador de CC y el Loss-Free Resistor (LFR) o resistor libre de pérdidas. La conexión en cascada de dos convertidores elevadores se ha realizado mediante diferentes enfoques: dos elementos canónicos idénticos, dos elementos canónicos diferentes y también mediante una única superficie de deslizamiento para controlar los dos convertidores. Las diferentes conexiones se han comparado en términos de prestaciones dinámicas, estabilidad y tiempo de establecimiento. Se podrá ver que la conexión en cascada de dos LFR es la mejor opción para las aplicaciones citadas en términos de prestaciones dinámicas y estabilidad. La conexión en cascada de dos LFR se utilizará en la implementación de una etapa de adaptación de impedancias entre un generador fotovoltaico y un bus de CC de 380 V. Para ello se utilizará un sistema MPPT basado en un algoritmo de control extremal. Se modelará la dinámica ideal deslizante de orden reducido a partir del modelo completo conmutado teniendo en cuenta les restricciones del modo deslizante, la característica no lineal del generador fotovoltaico y la dinámica del control MPPT. Además, la conexión en cascada de dos LFR se utilizará para inyectar la potencia proporcionada por un generador PV a una red de corriente alterna. A continuación, se llevará a cabo una comparación entre la conexión en cascada de dos LFR y dos convertidores con ganancia elevada: el convertidor Z-source y un convertidor basado en inductores acoplados. Estos convertidores se analizarán para identificar las ventajas y desventajas de cada topología frente a la conexión en cascada de dos LFR. La comparación se hará en términos de volumen, número de componentes, prestaciones dinámicas, estabilidad y rendimiento. Finalmente, los dos LFR conectados en cascada se utilizarán para diseñar una nano-red formada por n LFR conectados en paralelo que actuarán como etapa adaptadora entre n generadores fotovoltaicos y un bus de CC de 380 V. Cada generador fotovoltaico se conectará al bus de CC utilizando dos LFR conectados en cascada de forma que los n sistemas tendrán sus puertos de salida conectados en paralelo. Además, se conectará una batería al sistema a través de un convertidor bidireccional que será el encargado de regular la tensión del bus de CC de la nano-red. En el marco de esta tesis se han implementado diferentes prototipos experimentales para validar los análisis teóricos y las simulaciones numéricas efectuadas.
In this thesis, cascaded boost converters based on canonical elements under Sliding Mode Control (SMC) will be used as a solution for the high gain conversion ratio in PV applications. The three basic canonical elements for power processing are the DC-transformer, the DC-gyrator and the Loss Free resistor (LFR). Two cascaded boost converters will be synthesized based on one or two canonical elements using single or double sliding surfaces respectively. Different connections will be compared in terms of dynamic performance, stability, and settling time. It will be shown that the two cascaded LFRs is the best candidate for these kinds of applications in terms of dynamic performance and stability. The two cascaded LFRs will be applied to make an impedance matching between a PV generator and a DC voltage bus of 380 V. Maximum Power Point Tracker (MPPT) that employs an extremum-seeking control algorithm will be used. The ideal reduced-order sliding-mode dynamics model will be derived from the full-order switched model taking into account the sliding constraints, the nonlinear characteristic of the PV module and the dynamics of the MPPT controller. Moreover, the two cascaded LFRs will be used to connect a PV panel and AC distribution system. A comparison with other alternative converters for high gain conversion ratio will be carried out. The Z-source converter and the high step-up converter based on coupled-inductor are selected in order to make this comparison. These converters will be analyzed in order to address the advantages and disadvantages of each topology to be compared with the two cascaded LFRs in terms of volume, number of components, dynamic performance, stability and efficiency. Then, the two cascaded LFRs system will be used to synthesize a nanogrid consisting of n output paralleled two-stage boost converters which are used to connect n PV panels to a DC voltage bus of 380 V. Each PV panel is connected to the DC bus using two-stage cascaded LFRs and the n systems are connected in parallel at the output side which is then used as an interface between the panels and the DC grid. Moreover, a storage battery will be connected to the grid as a backup for the DC bus through a bidirectional converter and also for regulating the voltage of the DC bus. The thesis includes experimental implementations for validating the theoretical analysis and the numerical simulations.

Aim: The first customer is important because that it’s in many cases the only objective evidence that your product or service works in real life and that someone is willing to pay for it. The first customer is your first reference.   The aim of this study is to: Investigate how 7 start-up companies in the ICT-business developed reference. Establishing recommendations on what to focus on when creating reference customers. Present complementary recommendations for start-up companies regarding important factors, besides those investigated against the theory, which have been discovered to be important when building a successful company.   Method: The method in this study is a combination of a case study and cross-sectional study with qualitative data. The questions in the interviews were predefined and complemented with open ended questions according to the answers on the pre-defined questions. The data collected, the answers, were written down, summarized and analyzed regarding whether they did or did not support the theoretical statements investigated. A theoretical statement could be supported or not supported, partially or strongly   Result & Conclusions: The access to a professional network and good social skills are most important when establishing the first reference. Business skills can be developed during the process but the recommendation is to acquire or secure them as soon as possible. How to achieve the desired states has also been concluded.   Suggestions for future research: The largest limitation is the sample size of the data. Less than 10 companies were interviewed and some of the suggested statements can’t be significantly either confirmed or deferred. The study was also limited to one round of interviews. A study, with two rounds of interviews and a larger set of companies interviewed is suggested for further research. An extended study could also cover companies that didn’t survive the IT crash of 2000 and investigate if the suggested parameters and strategies were present and deployed or implemented.       Contribution of the thesis: The investigation has verified the importance of networks, customer type (brand name) and social capital when establishing a reference. It has also showed that the skills needed to develop a business doesn’t need to be present when company is established since it can be acquired and secured during the development of the first reference. It has also contributed with a set of recommendation for entrepreneurs in general not only regarding the establishment of reference customers where the most important recommendation is to build and maintain the personal and professional networks.

碩士
淡江大學
統計學系
92
In clinical trials, multiple testing procedures can be conducted to classify the new treatment with respect to each of the k standard treatments. The regular assumptions of the multiple testing procedures are normality and homogeneous variance. The main purpose of this thesis is to release the assumptions and employ nonparametric test statistic in multiple testing procedures. The numerical example based on normality and homogeneous variance shows that the proposed nonparametric testing procedures and the multiple testing procedures using T test statistic reach the same conclusions. The simulation studies indicate that the proposed nonparametric testing procedures coincide the required condition FWE≦α , and also they have higher power than the multiple T testing procedures under heterogeneous variance.

碩士
淡江大學
統計學系碩士班
97
Controlling false discovery rate (FDR) has been increasingly utilized in high dimensional screening studies where the multiplicity is a problem. It becomes an important issue to control the inflating type I error rate when tons of tested hypotheses are simultaneously conducted. Traditionally, familywise error rate (FWER) is used to control the overall type I error in the area of multiple comparison. However, when many null hypotheses are false, FWER tends to be more conservative and has less power. To improve the drawbacks of FWER, a simple approach based on FDR can be used. Two types of FDR procedures for multiple comparison are step-up and step-down procedures. The objective of this article is to compare the performance of current step-up and step-down procedures, and detect the pros and cons of these procedures. The simulated results indicate that Benjamini-Liu (1999a,1999b) procedures are more powerful if the number of tested hypotheses is small and many of the hypotheses are far from true, whereas Benjamini- Hochberg (1995) procedure has large power if the number of tested hypotheses is large.

碩士
國立臺北科技大學
電機工程系碩士班
101
In this thesis, a novel step-up converter is firstly proposed, i.e., the proposed type-1 non-isolated step-up converter, which combines one charge pump and one coupled inductor with the turns ratio. The corresponding voltage gain is greater than that of the existing step-up converter combing KY and buck-boost converters. Since the proposed converter possesses an output inductor, the output current is non-pulsating. However, the voltage gain of the firstly presented step-up converter is not high enough, so another step-up converter is delivered. This converter is modified from the firstly proposed converter, which has the same components, but a higher voltage gain. Considering the previous converters are all non-isolated, one isolated converter is engineered. This isolated converter possesses the same components as the proposed non-isolated converters. The benefit of these three proposed converters is that there is an output inductor in each proposed converter, so the output voltage ripple of each converter is smaller than that of the traditional boost converter. In addition, the proposed converters are simple and easily implemented. Finally, the detailed mathematical deductions, the design of the converter components and controllers, and some experimental results are provided to verify the feasibility and effectiveness.

碩士
遠東科技大學
電機工程研究所
107
This thesis proposes an architecture with both boost and buck converters,since the commercially available converters are only a single boost or buck converter, consider the need to meet both the need for boost and buck converters, Therefore, the Pulse Width Modulation (PWM) control technique is applied to boost and buck on the same circuit. This circuit simulates two different load conditions at the input DC 12V, 16V output to V_out119V and V_out212V pairs, Separate simulation experiments. At 12V half load, the efficiency is 87%, and when it is fully loaded, its efficiency reaches 88%. At 16V half load, the efficiency is 87%, and when it is fully loaded, its efficiency reaches 91%.

碩士
國立臺灣科技大學
電機工程系
99
By stacking a non-isolated current-fed push-pull converter with a novel voltage doubler rectifier technique, a non-isolated step-up converter is proposed in this thesis. In addition to inheriting the advantages of the current-fed push-pull converter, the proposed converter has several features, for instance, low voltage stress on the semiconductor and the recovery of the leakage energy. Consequently, low voltage rating MOSFET can be used resulting in achieving high conversion efficiency. Moreover, high power density is also achieved because the capacitance as well as the number of the output filter capacitor is significantly reduced. To demonstrate the feasibility of the proposed converter, the operation principles as well as the experimental results with 150 kHz, 36-75V input and 380V/500W output are described in this thesis.

博士
國立臺北科技大學
電機工程系博士班
101
In this dissertation, novel high step-up converters are presented. By using different pulse-width-modulation (PWM) control strategies and by changing the connection position of the anode of the diode, three different voltage conversion ratios can be obtained. These converters are constructed mainly based on bootstrap capacitors and boost inductors. Above all, two boost inductors with different values, connected in series, can still make the proposed converters work appropriately. Furthermore, although there are three switches in each converter, only one half-bridge gate driver and one low-side gate driver are needed, but no isolated gate driver would be needed. After the basic operating principles and mathematical deductions of the proposed converters are described, some experimental results are provided to verify the effectiveness of these converters.

碩士
國立清華大學
電機工程研究所
82
Higher switching frequencies of DC-DC converter, is made possible by power MOSFET transistor, and integrated- circuit pulse-width- modulating chip, which pack more control and supervisory features in a smaller volume. This work used conventional CMOS process technology to design three DC-DC step-up converters with different control methods, boost from adjustable input voltage to higher voltage (5V). layout example is also included in this work .

碩士
國立高雄第一科技大學
電子工程研究所
101
This thesis presents three novel high step-up DC-DC converters, which contain single-switch high step-up converter for general requirements, interleaved high step-up converter for high-power requirements and isolated high step-up converter for isolated requirements. All of the proposed high step-up converters utilize voltage multiplier techniques of coupled inductor and switched capacitor to implement high step-up conversion ratio. In addition, the passive lossless clamped function without extra switch and control circuit makes the leakage energy to be recycled to output terminal, which lifts the conversion efficiency and alleviates the voltage spike across switch. Finally, the specifications of proposed converters for performance verification are shown as below: Single-switch high step-up converter is tested with input voltage 12 V, output voltage 400 V and maximum power 200 W. Interleaved high step-up converter is tested with input voltage 40 V, output voltage 380 V and maximum power 1000 W. Isolated high step-up converter is tested with input voltage 40 V, output voltage 380 V and maximum power 500 W.

碩士
國立成功大學
電機工程學系碩博士班
96
Since portable electrical product is rising and flourishing, power management circuits which supply different voltage to different sub blocks are needed. The issues of this kind of power management circuits contain high efficiency, high accuracy, low noise and low cost. Compared with switching regulator, inductor-free charge-pump regulator has the advantage of lower cost. However, the structures of past charge-pump regulator are not regulated or regulated by PWM method. The structures which are not regulated have poor performance of accuracy, and structures regulated by PWM method are under high current stress for its short duration and the noise can’t be filtered easily for its frequency spectrum is not well defined. Our lab proposed current-controlled charge pump regulator several months ago. This kind of structure improves load-regulation magnificently, but it can’t supply voltage higher than input. When the voltage of battery gets lower than input voltage, the battery can’t supply stable output voltage. For this reason, a step-up/step down regulator is proposed. The frequency response of loop gain and the method of compensation and influence of clock have been researched. The design, implementation, testing and verification will also be presented in this report. The chip is implemented by the process of TSMC 0.35um 2P4M with a die area of 1.462x1.059 mm2. The input voltage of this circuit is set on 2.5V / 5V, and the output voltage is set on 3.3V. The measured results are listed as below. The maximum of load current is 9.2 mA. Measured load regulation is 2.06 mV/ mA, and measured line regulation is 0.15 mV / mA. If the power of active circuits isn’t considered, the efficiency is about 66%. If it is, the efficiency is about 57%.

碩士
國立成功大學
電機工程學系碩博士班
97
More and more battery-powered portable electronic products are introduced to the market in recent years. However, since the battery voltage typically decreases with time, a DC-DC converter is required to convert the time-varying battery voltage to a stable output voltage for the electronic circuits. This work implemented a versatile step-up/step-down dc-dc converter, which can convert a varied input voltage to a fixed 3.3V output voltage. The converter actually consists of a charge-pump-based converter and a low dropout regulator (LDO). Because a clean supply voltage is required for analog circuits, the LDO is included to effectively suppress the output voltage ripple of the charge-pump-based converter. The die area of the testchip is 1.4×1.4mm2. The chip was implemented by Taiwan Semiconductor Manufacturing Company (TSMC) 0.35μm 2P4M 5V mixed-signal polycide process, patronized by National Chip Implementation Center (CIC). According to the measured result, its input voltage range is 2.5-5 V, and its output voltage ripple is ultra low. The power efficiency is theoretical value approximately. The line regulation of charge-pump converter stage is 12.9mV/V (step-up mode) and 0.23V/V (step-down mode). The load regulation of charge-pump converter stage is about 1mV/mA. The line regulation of LDO stage is 0.8mV/V, and its load regulation is 0.294mV/mA.

碩士
國立臺北科技大學
電機工程系研究所
101
A high step-up converter, derived from the traditional forward converter, is presented herein, which uses an active clamping circuit to recycle the energy stored in the leakage inductance so as to reduce the voltage stress on the power switch. As compared with the traditional forward converter, the proposed converter, without the active clamping circuit considered, actually uses only one additional component so as to make the voltage conversion ratio improved greatly. In the thesis, the basis operating principles and mathematical deductions of the proposed converter are described in detail, and sequentially some simulated and experimental results are provided to verify the feasibility and effectiveness of such a converter. In addition, the filed-programmable gate array (FPGA), named EP1C3T100C8N made by Altera Co., is used as a system control kernel.

碩士
國立成功大學
系統及船舶機電工程學系
102
This thesis proposed a novel high step-up three port converter. The key concepts of the proposed converter are combined coupled-inductor technique, voltage lift technique and multi-winding technique of coupled-inductor. However, the using of the coupled-inductor induce serious voltage spike on power switches during the turned-off period. Therefore, for suppressing and recycling the energy that suffer from leakage energy, the passive snubber technique is applied. By adjusting the turns ratio and sufficient duty ratio of power switches. Also, each port of low voltage can achieve high voltage conversion ratio simultaneously. Operational principals, Boundary conduction mode analysis, steady state analysis, design process and control strategies of the proposed converter are presented and discussed. Finally, the prototype of the proposed converter with 250 W full-load, a low voltage input port(36 V~24 V) for Fuel Cell (FC) source, a bidirectional port for storage portions (48 V), and a high voltage port(400 V) for output is implemented to verify the theoretical analysis. The control strategies of the proposed converter is realized by a digital signal processor (DSP) controller.

碩士
國立成功大學
電機工程學系專班
97
In this thesis, a novel cascoded converter is proposed. Talking about the conventional Flyback converter, the energy of leakage inductor can not be used efficiently. Both the Buck-Boost converter and the Flyback converter are combined to make the energy of leakage inductor transfer to output load. Additionally, the stress of the power elements is reduced to enhance the whole efficiency. The transfer voltage ratio is increased by casecoding the input power supply with bulky output capacitors. First, the development procedure from traditional topology to casecoded topology is discussed. Second, the operation principles and design considerations of the proposed cascoded converter are discussed. Finally, a cascoded converter with input voltage 24V, output voltage 48V, and output power 144W is implemented. The results of this experiment are used to verify the analysis of theories.

碩士
中原大學
電子工程研究所
96
Portable electronic products need white LED which advantage is small volume size and saving power. Because battery has limited power, products can have longer lifetime by using LED. LED’s forward voltage is almost from 3.2V to 3.7V, series connection of the LEDs provides identical LED currents resulting in uniform brightness. Sum of the LED’s forward voltage is several times the battery voltage, so driving the LEDs need a boost converter. This paper presents a current-mode pulse width modulation boost converter circuit. Using system specifications to chose realizable system architecture, and detailed analysis the theorem, DC mode and AC mode to ensure the stability and reliability. Finial design the subcircuits and building a boost converter system. This paper is designed with TSMC 0.35 2P4M Mixed-Signal Polycide 3.3/5V Process. When load is one white LED and input voltage very from 3.3V to 3.6V, the transform efficiency is about 80%, average inductor current is 28mA, load current is flowed expected 20mA and its ripple (peak to peak) is smallerthan 33uA, and system power dissipation is less than 56.6mW.

博士
國立臺灣科技大學
電機工程系
100
This dissertation proposes three high step-up converters for high voltage dc applications. The three novel transformerless single-stage topologies are high step-up dc-dc converter, high step-up single-switch ac-dc converter and high step-up four-switch matrix ac-dc converter, respectively. Based on a conventional Cockcroft- Walton voltage multiplier (CW-VM), each proposed converter can provide high-voltage gain by increasing the stages of CW-VM without modifying the structure and control strategy of the main switch circuit. Moreover, this dissertation derives a new method of circuit representation for CW-VM, which simplifies the equivalent circuit. By using this method, the mathematical models corresponding to the three proposed converters are derived and used for simulations. The circuit operation principle, derivation of static gain, design considerations, and control strategy of each proposed converter are all detailed in this dissertation. Moreover, the current-fed analysis approach is used to derive a general expression of the output voltage ripple, which is a function of the output current and is able to facilitate the design of the system. In addition, a commercial average-current-mode control power factor correction (PFC) integrated circuit is used to achieve the control strategy for each proposed converter in continuous conduction mode. Three laboratory prototypes corresponding to the three proposed converters are built for test and evaluation. Both simulation and experimental results demonstrate the validity of each proposed converter for high voltage dc applications. The major features of the three proposed converters are summarized as follows: First, providing continuous input current with low ripple, high voltage gain and low voltage stress on the switches, diodes and capacitors, the proposed high step-up dc-dc converter is quite suitable for applying to low-level dc generation systems. Moreover, based on the n-stage CW-VM, this converter, without extra split capacitors, offers suitable dc sources for an (n+1)-level multilevel inverter. In this dissertation, the control strategy of the proposed high step-up dc-dc converter employs two independent frequencies, one of which operates at a high frequency such that the size of the boost inductor can be minimized, while the other one operates at relatively lower frequency and can be used to provide suitable output voltage ripple. Only one bidirectional switch and one boost inductor are added to a conventional CW-VM circuit, and this forms the second proposed high step-up single-switch ac-dc converter. Compared with the conventional CW-VM circuit, the proposed converter provides half-wave symmetry and low-distorted line current, high power factor at the ac source side and a regulated dc output voltage for a wide load range. In this dissertation, the power factor control strategy of this single-switch ac-dc converter is implemented by one-cycle control, in which the multiplier and sensing of the input ac voltage are unnecessary. Thus, this leads to simplifying the design of the controller. Finally, the third proposed converter is the high step-up four-switch matrix ac-dc converter, which is formed by arranging a four-bidirectional-switch matrix converter between the ac source and the CW-VM. The proposed matrix converter provides high quality of line conditions, adjustable output voltage, and especially low output ripple. Two independent frequencies are used to operate these four bidirectional switches, one of which is associated with PFC control and the other is used to set the output frequency of the matrix converter. The former operates at a high frequency such that the line current can be nearly sinusoidal, while the latter operates at relatively lower frequency and can be used to provide suitable output voltage ripple.

碩士
崑山科技大學
電機工程研究所
104
In this thesis, a novel interleaved ipsilateral coupling high step-up converter (IICHSUC) and a novel interleaved contralateral coupling high step-up converter (ICCHSUC) are proposed by applying the coupled inductor multiplier voltage module, coupled inductor voltage adder module and boost capacitor voltage adder module to an interleaved boost converter, in which a phase shift of 180 degree between the switching pulses are provided to the main switches of two parallel connected boost converter units. The operating principle, component design, driving circuit design and voltage controller design are all presented in detail herein. The proposed interleaved high step-up converters can provide high output voltage without using the extreme duty ratio. A serious reverse-recovery problem can also be solved, because the energy can be feedback to input from the secondary winding. In addition, because the interleaving technique is also applied to the proposed converter, the proposed converter thus exhibits the capabilities of current sharing, low current stress, low input current ripple and low output voltage ripple in high power applications. Finally, input voltage 40 V, output voltage 400 V, switching frequency 40 kHz and output power 200 W~1000 W prototypes of IICHSUC and ICCHSUC are implemented. The IsSpice simulations and experimental results are thus presented to verify the theoretical analysis of the proposed converters. Furthermore, according to the measurements of power efficiency, it reveals that the IICHSUC has the highest efficiency of 97.9 %, and ICCHSUC has the highest efficiency of 97.3 %. On the other hand, the small-signal model is derived from the curve fitting of the frequency response plot. A voltage controller is then designed to regulate the output voltage despite of the variations of input voltage and load.

碩士
國立彰化師範大學
電機工程學系
98
The common rechargeable batteries are lead-acid batteries, Ni-MH batteries and Lithium batteries. Because we need to consider several factors including cost, stability, and preservation, therefore, the most common usage of rechargeable batteries still are lead-acid batteries. In order to improve charging efficiency and life, the charger and charging method are very important. To adapt the conditions of many input sources, the buck-boost converter still is a good choice. A buck-boost converter has high practicability and convenience. Although there are many PWM IC, but few of them can control the buck-boost converter simultaneously at low cost. In this thesis, we propose a new buck-boost configuration which uses a microprocessor controller to control the buck-boost charging circuit. It provides 10-20V for the 12V lead-acid storage battery, and observe the battery status and the voltage values. The feedback signals delivered to the microprocessor are used to control the switch. In this design, we use three-stage charging method (constant current charging, constant voltage charging, and float charging) to enhance the charging performance.

碩士
國立成功大學
電機工程學系碩博士班
96
A bidirectional DC-DC converter with high step-up/step-down voltage ratio is proposed. It is used to bidirectional transform energy between low-voltage battery and high-voltage DC bus. When the proposed converter is operated in the discharging mode, input is battery and output is DC bus. Circuit characteristic is composed with forward converter and flyback converter. Because the output side is cascade connected, the high step-up voltage ratio is obtained. When it is operated in the charging mode, input is DC bus and output is battery. It is integrated with flyback converter and buck converter by coupled inductor. Several bidirectional converters are briefly reviewed in thesis at first. And then, operational principles and steady-state characteristics are discussed. Finally, a bidirectional DC-DC converter with low voltage 24 V, high voltage 200 V and output power 200 W is implemented to validate theoretical analysis.

碩士
雲林科技大學
電機工程系碩士班
96
This thesis presents a double-flyback converter with active clamp technigue and a double boost-flyback converter. In the proposed converter, the active-clamp circuit is used to eliminate voltage spike, achieve zero voltage switching (ZVS), and to improve the conversion efficiency. The integrated double boost-flyback converter uses coupled-inductor technigue to achieve high step-up voltage. The voltage gain and efficiency at steady state are derived using the principles of inductor volt-second balance. Finally, the operating principles, theoretical analysis and design methodology of the proposed converters are presented and the experimental results are provided to verify the system performance.

碩士
國立成功大學
電機工程學系
104
In this thesis, a novel high step-up DC-DC converter with ZVZCS is proposed based on several existing coupled-inductor and switching-capacitor topologies. According to the characteristics of renewable energy sources, these kinds of converters are usually required to have a high conversion ratio, high efficiency and large power capacity. Therefore, the interleaving and active-clamp techniques are introduced. During steady-state operating modes of the proposed converter, the leakage inductor of the coupled inductors resonates with two switching capacitors. Under different resonant frequencies, ZVS turn-on and ZCS turn-off can be realized for certain power switches and rectifying diodes, respectively. Therefore, the switching loss and reverse recovery problems are alleviated, which improves the efficiency of the converter. Thanks to the interleaving mechanism and more switches, the turn ratio of each coupled inductor can be reduced dramatically, along with less current stress in the primary-side winding. Therefore, the power capacity can be improved significantly. Before experiment, steady-state performance including the voltage conversion ratio is derived and compared with existing ones. In addition, the mode boundary map for distinguishing soft-switching modes is depicted and verified by the software simulation. Finally, a prototype with 24 V input voltage, 400 V output voltage and 800 W output power using controller TMDSDOCK28035 is implemented in the laboratory to verify the feasibility of the proposed converter.

碩士
元智大學
工業工程與管理學系
105
Comparing multiple linear profiles can be used to select manufacturing processes. Quality characteristics of products can be expressed by linear profiles. If multiple processes can satisfy the existing product specifications, reduce production time, reduce cost or have other advantages, comparing multiple linear profiles can be applied to select the alternative process. In this research, the multiple comparisons of many-to-one linear profiles is established for simple and multiple linear profiles. The comparison process considers allowing subtle differences between profiles for practical usage. To enhance the power of multiple comparisons between profiles, this research investigates two test statistics, the maximum of difference statistic studied in literature and the sum of difference statistic proposed in this research, and proposes the step-up procedure to distinguish profiles from the control group. This research simulates the power of the step-up procedure when having different shift level in the regression coefficients. The results show that the step-up procedure of two test statistics are more efficient in distinguishing linear profiles than the literature method.

碩士
遠東科技大學
電機工程研究所
105
This thesis presents a high step-up DC-DC converter. Two semi-stage, which integrating a DC-DC boost converter with a transformerless DC-DC converters to achieve high step-up voltage gain, are adopted for the proposed converter. The two semi-stage are operated in continuous conduction mode. The voltage gain of this converter is multiplied by the voltage gain of the front and the rear semi-stage. During the switch on-period, the inductors of the front and rear semi-stage. During the switch off-period, the energies stored in the inductors of the front and rear semi-stage are transferred to the intermediate capacitor and load respectively. Thus, the proposed converter can achieve high voltage conversion ratio. The operating principles and steady-state analysis are discussed in detail. Finally, a laboratory prototype with an input voltage of 12V, an output voltage of 100V, an output power of 40W is implemented to verify the performance of the proposed converter.

碩士
國立清華大學
材料科學工程學系
89
The study of rising the voltage of AAA batteries from 1.5V to 3.3V was investigated to supply the power of the Walkman designed for MP3. Five step-up converters, MAX1674、RT9262、XC6832、AIC1639、and RN5RK, were selected to improve the circuits of the walkman. Among the converters, the most suitable one need to be chosen according to conversion efficiency、start-up voltage、loading current、and price。 In power management, operating voltage was modulated under 3.3V、3.0V、2.7V for the effect of the system. According to the power management of MP3, several different circuits were designed to make the system more efficient。 According to the result of the experiment tested under one battery, MAX1674 step-up circuit was the best choice under synchronous rectifier technique. Except high conversion efficiency，MAX1674 step-up circuit also showed excellent performance in the aspect of start-up voltage and loading current. Decreasing of the operating voltage came along with the longer lifetime of batteries. At 2.7V， the lifetime of batteries was the longest. If the operating voltage was under 2.7V， there would be some errors in the system。

碩士
雲林科技大學
電機工程系碩士班
97
An active-clamp dual series-resonant step up converter is proposed in this thesis. By using the same topology, both a ZVZCS (zero-voltage zero-current switching) converter and another ZVS (zero-voltage switching) converter can be implemented. Two small transformers are used at the proposed topology to instead of a large transformer, which are much cost effective. An active-clamp circuit is used to absorb the energy stored in the leakage inductor of transformer, clamp voltage stresses across switches, and realize the ZVS turn-on of switches to alleviate the switching losses. The ZVZCS converter not only achieves the ZVS turn-on, but also carries out the ZCS (zero-current switching) turn-off to remove the reverse-recovery problem on output diodes due to choosing the angle frequency on the secondary side properly. The output power of the ZVS converter is much larger than the ZVZCS converter. Analysis of mode operation, design considerations and experimental results of each converter are described in detail. Also, the restriction of the ZVZCS converter is discussed in the section Ⅴ of this thesis. Finally, a 200W ZVZCS prototype and a 600W ZVS prototype are implemented to verify the practicability of the proposed converter.

碩士
國立中央大學
電機工程研究所
100
With the improvement of manufacturing process, more and more transistors can be placed in a chip. It drives the demand to integrate the whole system into a single chip. However, different blocks may require different voltage supplies, which require power converters to generate those voltages. In order to accelerate the design of power converters, an automatic design flow for the voltage-controlled step-up switching converters is proposed. This flow includes the design of the converter circuit and control circuit. It also considers the parasitic resistance of each component to ensure that the design can confirm the results with real devices. To accomplish the flow, an automatic synthesis tool is implemented. Users can assign the specifications of the converter circuit on a simple graphical user interface (GUI). The steady state and small signal analysis are then auomatically executed to generate the parameter of each component by a C program. The result will be measured through HSpice simulation to confirm the circuit performance. All steps have been integrated with Tcl/Tk shell scripts and successfully tested on Linux platform. All the generated results meet the required specifications in the demonstrated cases.

碩士
國立高雄第一科技大學
電子工程系碩士班
106
This thesis presents a novel three-port high step-up/step-down bidirectional DC/DC converter for photovoltaic systems. The proposed converter combines a high step-up converter which is used to step-up PV module to DC bus 200V and a battery charge/discharge bidirectional converter to form an improved three-port bidirectional converter. When the energy supplied from the PV modules is sufficient, it can step-up the output of PV modules and provide energy to the DC bus while charging the battery at the same time. However, the DC bus voltage is provided by the battery while lack of energy supply from the PV modules. When the proposed converter is operated at the step-down mode, the DC-blocking capacitor in the high-voltage side is used to reduce the voltage on the transformer and achieve a high step-down performance. Moreover, the energy stored in the leakage inductance is recycled to the DC-blocking capacitor and synchronous rectification in switch during the step-up mode to reduce switch loss to increase the system’s overall efficiency. At last, a 500W three-port bidirectional converter was implemented to verify the feasibility and practicability. The maximum efficiency of the proposed converter operated under high step-up mode for the PV modules is 95.4%, while battery step-up mode is 94.3% and step-down mode is 94.7%

碩士
國立中山大學
電機工程學系研究所
104
This thesis proposes a novel bi-directional full-wave rectifier with higher step-up and step-down voltage ratio which can be used in renewable energy generation systems. The low-voltage side of this circuit is full-bridge topology, combined with transformer, and the high-voltage side is composed of two full-wave rectifier circuits to construct a four times voltage multiplier rectifier. In the boost mode, the power switches of low-voltage side are driving by phase-shift control to reduce the stresses on the power switches. Meanwhile, the Time Division Multiplex (TDM) control strategy is used to transfer energy from the output rectifier diodes to the output capacitors at different time intervals. TDM control strategy can reduce voltage stress of the output capacitors and rectifier diodes. The voltages of output capacitors can almost achieve equalizing voltage. The four times output voltage can then be realized due to the superposition of the output capacitor voltages. In buck mode, the different capacitors based on TDM control strategy can release energy to load in different time intervals. All capacitor voltages in the buck mode are also almost same. A novel bi-directional full-bridge full-wave rectifier with higher step-up and step-down voltage ratio is implemented in this thesis. The specifications for the boost and buck modes are 24V DC input, 200V DC output, and rated power 100W and 200V DC input, 24V DC output, and rated power 100W, respectively. Experimental results show that the bi-directional functionality of the proposed circuit can be achieved. Besides, the conversion efficiency for both boost and buck modes is above 86%. Experimental and simulated results also indicate that the voltage stresses of output capacitors and rectifier diodes in the proposed four times voltage multiplier rectifier is less than the conventional half-wave or full-wave rectifiers. Therefore, the proposed bi-directional circuit has great potential to be used in the converters of renewable energy generation systems requiring higher step-up and step-down voltage ratio.

碩士
國立高雄科技大學
電子工程系
107
This thesis proposes a novel high efficiency three-port bidirectional DC/DC converter for photovoltaic (PV) systems. A PV system output is stepped up to supply to a DC bus or DC load while charging the battery. When the PV output is insufficient, battery voltage will be stepped up to the DC bus, and when the DC bus has excess energy, it will be stepped down to charge the battery. Thus, a three-port bidirectional high step-up / step-down converter is achieved. In this thesis, a common core coupled inductor is designed and adopted in the proposed converter. Power switches and diodes in the circuit are shared to achieve the bidirectional operation. In the step-up mode, the clamp capacitor is used to reduce the voltage spike on the main switches; in addition to the voltage-doubling capacitor is recovered energy from the secondary side leakage inductance. Also, the input capacitors recover the primary side leakage inductance energy in the step-down mode, so that the converter can improve the conversion efficiency. Finally, this thesis implements a 500W three-port bidirectional converter to verify the feasibility and practicability of the proposed topology. According to the measurement results, the highest efficiency of the PV step-up mode is 94.3%, and the highest efficiency of the battery step-up mode is 94.1%, while the highest efficiency of the step-down mode is 95.2%.

碩士
國立清華大學
電機工程學系
90
Inverters are widely used in various applications. However, traditional inverter configuration basically belongs to a step/down topology. In other words, the maximum peak voltage of the output AC voltage is limited to the input DC voltage. Hence, in case a higher output voltage is needed, it is necessary to either cascade one more stage of step/up CD converter or add an step/up transformer. This will, of course, result in larger size, lower efficiency and higher cost. In view of there, it is the main objection of this thesis to develop a single stage step up/down inverter without using an extra transformer. Basically, the contributions of this thesis may be summarized as follows. First, a novel single stage step up/down inverter without using a transformer is proposed to extend operation range of the output AC voltage. In fact, due to the four-quadrant operation capability of the proposed inverter, the new inverter can also be operated as an AC to DC converter. Second, mathematical model of the proposed inverter is also derived for feedback controller design and implementation. Third, in order to achieve a better performance, a closed loop controller is also presented to satisfy the desired specification. Finally, a hardware prototype of the proposed inverter is constructed to verify the feasibility of the proposed inverter.

碩士
國立臺灣科技大學
電機工程系
99
A buck-derived topology is presented to realize the step-up and step-down function for green energy power applications. In addition to having required voltage conversion gain, it has recovery of the transformer leakage energy and reduced input current ripple resulting in decreasing both EMI intensity and RMS value of input current. Consequently, the size of the input filter can be reduced significantly. Moreover, the input current ripple reduction mechanism can be further improved by generating an opposite current to cancel the input current ripple. Consequently, the input current becomes a continuous waveform instead of the pulsating shape. These properties make it desirable for high frequency high efficiency step-up and step-down voltage gain power conversion applications, such as green energy powered telecommunication system. To demonstrate its feasibility, the operational principle and the experiments of the presented converters with 36~75V input and 48V/10A output are described in this thesis.

碩士
國立政治大學
國際經營管理英語碩士學位學程(IMBA)
104
Each year, only around 10% of the produced films will go to theatrical release, and 90% of the produced films might be the missing jewels lost in time. In Taiwan, movie distributors will act as this filter role to find out those 10% films. In this case, we will introduce the basic knowledge of the industry and discuss the evaluation process of the distributors and at the end reaching our conclusions and suggestions.

碩士
國立成功大學
電機工程學系碩博士班
98
In this thesis, a high step-up forward/flyback converter with active-clamp circuit is proposed. The circuit topology of the proposed converter consists of a transformer, switch, resonant capacitor, an active-clamp circuit, and the output voltage doubler circuit. By utilizing the transformer and output voltage doubler, the proposed converter can achieve high voltage gain. The proposed converter functions as the forward and flyback integrated converter. In additional the active-clamp circuit is employed to recycle the leakage-inductance energy of the transformer and thus the stresses on the switches are reduced and zero-voltage-switching (ZVS) are achieved. Thus, the system efficiency can be improved. Finally, a prototype circuit with 24-V input voltage, 200-V/ 400-W output power is implemented to verify the performance.

碩士
國立高雄第一科技大學
電子工程研究所
102
In this thesis, a non-isolated single-switch cascaded high step-up converter is proposed. Its configuration is constituted by coupled inductors, clamp circuit, cascaded capacitors to achieve high step-up output. Only one switch is used in the proposed converter, and it can reduce cost efficiently and simplify the control the proposed converter. Also, it possesses energy-recycle mechanism to recycle the spike energy of leakage inductor. In addition, a clamp circuit is used to reduce the voltage-stress across the switch, while cascaded design to reduce the voltage-stress across diodes and output capacitor, so the proposed converter can select low voltage-stress switch to reduce the circuit loss and improve the efficiency of the converter. Thus the proposed converter possesses the advantages of high efficiency, high modularity, ease maintenance and ease selected components. Finally, a 400W non-isolated cascaded high-step up converter is implemented in this thesis, and its input voltage is 48V and output voltage is 400V. A microcontroller dsPIC30F4011 is used to control the converter and verify the system effects and feasibility. The maximum efficiency of the proposed converter is 95% and the efficiency is 93% under full load.

碩士
國立高雄第一科技大學
電子工程研究所
103
This thesis proposes an isolated bidirectional DC/DC converter with high voltage conversion ratio, which mainly consists of two fundamental Boost-type converters and one transformer. While operating in step-up mode, by means of stacking up voltage to switched capacitors the converter can lower voltage stresses across semiconductors in low-voltage side. In addition, the proposed converter can inherently achieve soft-switching feature. That is, it is able to decrease power loss and reduce the component temperature. To further promote overall efficiency, the leakage energy can be recycled to switched capacitors no matter in which mode the converter operates. Operation principle, steady-state analysis, and mathematical derivation are described in this thesis. Finally, simulations and experimental results are illustrated to verify the feasibility and correctness of the proposed converter.

碩士
國立聯合大學
電子工程學系碩士班
96
In order to lengthen the employ time and saving power in the consumer electronic products, low operation voltage and low dissipate energy are the important developed issues. In this thesis, a low-voltage DC to DC step-up converter circuit will be investigated, which will enable a lower power voltage step-up to a target voltage by this converter circuit. The chief architectures are the Pulse Frequency Modulation ( PFM ) and the Pulse Width Modulation ( PWM ), they are operated in the light loading and heavy loading to decrease the power dissipation, respectively. Eventually, this PFM module will work under 0.77V, the PWM can work under 0.75V. Meanwhile, the whole chip were established by the UMC 0.5μm 1P3M CMOS model.

博士
國立成功大學
電機工程學系碩博士班
101
In this dissertation, the step-up converters are analyzed with voltage source and current source. When switch is turned on and off, the coupled-inductor changes the polarity on the secondary-side. Adjustable voltage source and current source are created. According to the characteristic, the switched-capacitor and voltage-lift techniques can be combined with it. Two step-up methods are proposed. Then, systematize high step-up converters with the step-up methods, five high step-up converters are proposed. Conventionally, the high step-up converters use more turns ratio to achieve high step-up gain. The leakage inductor is large and efficiency is low. Some high step-up converters use a lot of capacitors to add the step-up gain. The more stage transition is used and efficiency is low. High step-up converters used twp proposed methods to design can have high voltage gain than others. Thus, fewer turns ratio and fewer capacitors are used to achieve high step-up gain. In addition, all of four converters have lossless passive snubber circuit, the energy of leakage inductor is recycled. The low on-resister can be adopted and conduction loss is reduced. High efficiency is achieved. In hardware implementation, four converters are easy to realize because theses converters have only one switch and don’t need high-side driver. The control circuit is also easy to design. The mode analysis is described clearly in this dissertation. Also, the step-up gain and boundary condition of these converters are analyzed and calculated. Finally, the prototypes of five converters are built to demonstrate the performance which includes the voltage gain, voltage stress of semiconductors, efficiency and boundary condition. These high step-up converters are suitable for becoming front-end stage of solar system, full cell converter, uninterruptible power supply.

碩士
國立臺灣科技大學
電機工程系
101
This thesis proposes an interleaved high step-up multilevel converter for low-voltage dc generation systems such as photovoltaic modules. The converter consists of a two-stage power converter topology. The first stage converter can provide high step-up ratio without using the step-up transformers based on the high step-up ratio characteristic of Cockcroft-Walton (CW) voltage multiplier and reduce input current ripple due to interleaved operation. Because of the output side of CW multiplier consists of cascaded capacitors, the second stage utilizes five-level inverter to provide single phase 60Hz ac output and reduce output voltage harmonic distortion. In additional, the converter is applied to photovoltaic generation system. The perturbation and observation method is used for maximum power point tracking to achieve the maximum output power of solar energy and implemented by a digital signal processor (DSP, TMS320F28069). The validity of the proposed solar system is verified by a voltage recorder recording the variation of the power from system in whole day.