Academic literature on the topic 'Portable power supply'

Emergency Portable Solar Power Supply is a product which uses renewable energy sources as the main sources of electricity which is sunlight. According to World Energy Outlook (WEO) 2018, the percentage of renewable energy used as a source to generate electricity grew by 17% higher than the 10-year average and solar energy contributed more than a third despite accounting for just 21% of the total. The main objective of this product is to create clean energy emergency portable solar power supply by using non-conventional energy source and green technology which can be used during any contingency happens and also for the usage for rural area with non-electric power source. This project was started by calculation of the system design for determining the characteristic that need to be used for all components that related to this solar system such as battery, charge controller, solar panel and etc. The overall system of this portable solar power supply is 12V system. This design can last for 2 days without charging and the minimum hour for the battery to be charged is around 6 hours. This product can supply maximum up to 100W of DC and AC power supply. In a conclusion, this product is very portable and greener product the usage of solar energy as the main sources to generate electricity.

With the increase of electrical equipment, people's lives become increasingly dependent on electricity. In case of power interruption, people need to use emergency power supply.A portable solar photovoltaic mobile emergency power supply is designed in this paper,which uses embedded solar panels to provide power energy, and fitted with other complementary power input.The designed portable solar photovoltaic mobile emergency power supply provides optional DC12V/5V and AC220V output to meet the application requirements on different occasions.Through experimental tests on designed power supply prototype, the results indicated the power supply has good performance in all aspects.The designed and developed portable solar photovoltaic mobile emergency power supply has characteristics of energy saving, full-featured, high practicability and wide application [1-5].

Renewable energy from solar cells is a type of alternative energy for consumers, especially those far from electricity, and saves electrical energy. This research developed an innovative tool for portable solar power generators as a source of energy, which stores electrical energy in two ways, namely solar cells and transformers. Furthermore, this research is expected to improve innovation tools for more efficient electricity supply and energy use, especially for rural communities. It also uses a variety of battery capacities to test portable power supplies. The results showed that the power supply using 100 Wp solar cells produced a capacity of 20 Ah, 60 Ah, and 100 Ah on the battery. Charging with a solar energy source on a 20 Ah battery takes a duration of 5 hours to be fully charged, while 60 Ah and 100 Ah batteries cannot be fully charged in one day. Charging a battery that has been run at a full level takes a duration of 15 hours at a temperature of 30oC to 34oC. Finally, this tool is expected to add variety to locally manufactured products.

Portable devices are mostly powered by battery. With the products tending to the direction of light, thin, short and multi-functional integration, the power requirements of portable devices are increasing all the time, but the energy density of battery is far behind the speed, the improvement of performance relies heavily on the power management technology. Therefore, it’s needed that manage the power of whole system with the integrated viewpoint to reduce power consumption and extend the system work time. After the analysis and research for power management technologies, one kind of a combination of hardware and software power management solution is proposed. The power management IC with embedded Linux operating system's Dynamic Power Management technology, better to reduce system power consumption, meets the requirements of the power system supplied by portable equipment.

Abstract In order to facilitate the testing needs of electronic engineers, a multi-channel isolation adjustable switching regulated power supply controlled by an STM32 single-chip microcomputer is designed [1]. The power supply is programmable and adjustable by a single-chip microcomputer, and the humanized display operation interface is combined with the high efficiency of switching the power supply. It can realize three channels of 30v2a isolated output, and realize one channel of 90v2a or 30v6a output through a relay automatic switching series-parallel combination, to maximize power density. The power supply has the characteristics of high integration, small volume, large power, large adjustable range, high precision, and high efficiency. It can be applied to the debugging and operation of most electronic equipment.

In this article, it takes the small power mechanical exoskeleton with fuel cells as the main application target. Based on different two hydrogen supply methods, high-pressure hydrogen cylinders and portable metal hydride hydrogen cylinders, the box structure and shape design of small power PEMFC is made. It cannot only provide power as a independent component using high-pressure hydrogen cylinders supply gas equipment, but also as transportation power or portable equipment by installing rapidly metal hydride hydrogen storage cylinders, which realized the use of reliability, flexibility and convenience for mechanical exoskeleton.

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2008.
Includes bibliographical references (p. 86-87).
A multistage bandgap circuit with very high power supply rejection ratio was designed and simulated. The key features of this bandgap include multiple power modes, low power consumption and a novel resistor trimming strategy. This design was completed in deep submicron CMOS technology, and is especially suited for portable applications. The bandgap designed achieves over 90 dB of power supply rejection and less than 17 microvolts of noise without any external filtering. With an external filtering capacitor, this performance is significantly enhanced. In addition, the design includes an efficient voltage-to-current converter and a fast-charge circuit for charging the external capacitor.
by Siddharth Sundar.
M.Eng.

2013/2014
Lo sviluppo sostenibile è una sfida prioritaria per la nostra società. La possibilità di costruire un futuro sostenibile, mantenendo al contempo alti standard nella qualità della vita e preservando risorse e ambiente, dipende dalla disponibilità di metodi per la produzione verde di energía e prodotti chimici. La produzione simultanea di prodotti chimici ed energía può essere ottenuta nelle celle a combustibile che impiegano combustibili liquidi (Direct Liquid Fuel Cells – DLFC), dispositivi in cui l’energia chimica contenuta nelle molecole di combustibile è convertita direttamente in energía elettrica. Le DLFC impiegano solitamente combustibili a base di piccole molecole organiche quali ad esempio alcoli ed acido formico. Questi combustibili sono di particolare interesse, dal momento che possono essere ottenuti a partire da biomassa, con un impatto minore sulle emissioni di gas serra rispetto ai combustibili fossili. Allo stato attuale le DLFC impiegano platino in quantità elevate. Questo per due ragioni: i) il platino è un buon catalizzatore sia per l’ossidazione di composti organici che per la riduzione dell’ossigeno e ii) il platino è stabile in ambiente acido. E’ importante sottolineare che le attuali DLFC impiegano membrane a scambio protonico come elettroliti e dunque richiedono ambienti fortemente acidi per avere un’adeguata conducibilità. Le DLFC impiegano carichi di platino maggiori di 1 mg cm-2, un fatto che ne limita molto la possibilità di diffusione commerciale. In questo lavoro, grazie alla disponibilità di membrane a scambio anionico ad elevata conducibilità (Tokuyama A-201), abbiamo sviluppato delle DLFC alcaline (Anion Exchange Membrane Direct Liquid Fuel Cells – AEM-DLFC). Ciò e’ stato fatto con l’obiettivo di eliminare il platino dai dispositivi. E’ infatti noto che il palladio è un catalizzatore molto attivo per l’ossidazione delle piccole molecole organiche in ambiente alcalino e che la reazione di riduzione dell’ossigeno puo’ essere catalizzata da composti di ferro e cobalto (es. ftalocianine). La tecnología qui riportatata si basa sull’impiego di anodi di palladio supportati da carbon black (Vulcan XC-72), membrane a scambio anionico e ftalocianine di ferro e cobalto subbortate da carbon black con maggiore area superficiale rispetto a quello impiegato all’anodo (Ketjen Black 600). Un fatto importante è che le ftalocianine di ferro e cobalto non sono attive per l’ossidazione di molecole organiche. Ciò è particolarmente rilevante per le fuel cells perché il cross-over del combustibile attraverso la membrana non produce significative cadute di potenziale e quindi dell’efficienza energetica. La parte sperimentale della tesi inizia con un capitolo in cui si decrivono le prestazioni di AEM-DLFC esenti da platino ed alimentate ad etanolo. Questa parte del lavoro è particolarmente rilevante dal momento che è la prima e completa caratterizzazione della performance energetica di questi dispositivi. In particolare si sono determinati i seguenti parametri: i) massima densità di potenza, ii) efficienza energetica e iii) l’energia prodotta per singolo batch di combustibile. Tutti questi parametri sono stati determinati in funzione della composizione del combustibile. Abbiamo scoperto che la composizione del combustibile che massimizza uno dei parametri sopra riportati generalmente ha effetti negativi sugli altri. E’ dunque necesario definire la composizione del combustibile in funzione della particolare applicazione cui il dispositivo è destinato. Abbiamo inoltre studiato l’effetto dell’aggiunta di un ossido promotore, la ceria, al catalizatore anódico, mostrando che le prestazioni migliorano significativamente. In alcuni casi l’efficienza energetica può essere migliorata anche di più del 100% grazie alla semplice aggiunta di dell’ossido promotore. Il capitolo successivo e’ dedicato alle celle a combustile che impiegano combustibili a base di formiato (Direct Formate Fuel Cells – DFFC). In questo caso si sono impiegati catalizzatori nanostrutturati di Pd supportato da Vulcan XC-72 e ftalocianine di ferro e cobalto, rispettivamente all’anodo ed al catodo, ottenendo un potenziale di circuito aperto superiore ad 1 V. Le celle alcaline al formiato hanno prodotto una densità massima di potenza superiore alle celle alcaline che impiegano metanolo ed etanolo, ed anche alle celle acide che impiegano acido formico. In particolare l’efficienza energetica delle celle al formiato è stata superiore di un fattore 4 a quella delle migliori celle alcaline ad etanolo. Questo e’ un punto cruciale per l’applicazione pratica della tecnología proposta. Infatti l’efficienza energetica e’ uno dei cardini per il raggiungimento della sostenibilità e, senza dubbio, il vincolo principale per i sistemi che devono produrre grandi quantita’ di energía, come la generazione stazionaria di energía elettrica. Anche nel caso delle celle al formiato, abbiamo osservato che la composizione del combustibile è essenziale nel definire la performance energetica. Abbiamo mostrato che la massima densità di potenza si ottiene con un combustibile che contiene formiato 2 M e KOH 2 M, mentre l’energia per singolo batch di combustibile, la migliore conversione del combustibile e l’efficienza energetica sono migliori per il formiato 4 M e KOH 4 M. Al fine di migliorare la capacità del palladio di catalizzare l’ossidazione elettrochimica di composti organici rinnovabili, abbiamo sviluppato un metodo elettrochimico originale per il trattamento delle superfici degli elettrodi. Il trattamento consiste nell’applicazione di un potenziale ad onda quadra (Square Wave Potential – SWP) che produce un aumento della rugosità superficiale e una modifica della distribuzione delle terminazioni cristalline della superficie, incrementando la densità degli atomi di Pd superficiali a basso numero di coordinazione (< 8). Il trattamento si è rivelato efficace nel migliorare la cinetica di ossidaizione dell’etanolo, dell’etilen glicole e del glicerolo. I trattementi sviluppati hanno prodotto incrementi dell’attività fino ad un fattore 5.6. L’analisi FTIR dei processi di ossidazione ha dimostrato che anche la distribuzione dei prodotti di ossidazione e’ affetta dal trattamento. In particolate abbiamo riscontrato un incremento nella capacità dei catalizzatori ottenuti per SWP di rompere il legame C-C. Il trattamento elettrochimico con potenziale ad onda quadra è stato sviluppato anche per le superfici di platino, con l’obbiettivo di fornire uno strumento per ridurne il contenuto nelle fuel cells quando non sia possibile eliminarlo completamente. Nel caso del platino si è riscontrato che il parámetro piu’ importante per l’efficienza del trattamento è il periodo dell’onda quadra. Le superfici più attive si sono ottenute con un periodo di trattamento di 120 minuti, mentra la stabilità massima si e’ avuta per campioni trattati con onde quadre con periodo di 360 minuti. Tramite esperimenti FTIR si è inoltre concluso che nel caso del platino il trattamento inibisce la rottura del legame C-C. Questo fatto è importante perchè limita la formazione di frammenti CO che sono le principali specie che avvelenano gli elettrocatalizzatori a base di platino. Il capitolo 7 è dedicato allo studio dei meccanismi di deattivazione dei catalizzatori di palladio per l’ossidazione elettrochimica in ambente alcalino di alcoli. L’argomento è rilevante poichè la deattivazione è una delle principali cause che limita la diffusione di questi dispositivi. Abbiamo dimostrato che la formazione di ossidi è la causa che determina maggiormente la degradazione della performance catalítica. Siamo giunti a questa conclusione combinando le informazioni proveniente da indagini elettrochimiche ed esperimenti che impiegano la radiazione di sincrotrone. L’analisi degli spettri XANES (Near Edge X-ray Absorption Spectroscopy) ha mostrato che il palladio è presente nella sua forma metallica nei catalizzatori freschi, mentre è completamente ossidato dopo l’impiego in fuel cells. Nello studio si conclude che per allungare la vita degli anodi a base di palladio è necesario che il catalizzatore anodico non sia esposto a potenziali superiori a 0.7 V. Ciò è possibile in pratica con una semplice elettronica di controllo da abbinare alla cella. Al fine di aumentare la cinetica di ossidazione abbiamo provveduto ad effettuare esperimenti di ossidazione dell’etanolo a temperatura intermedie (> 100 °C) in autoclave. Abbiamo osservato che l’incremento della temperatura aumenta in misura significativa la capacità dei catalizzatori di ossidare l’etanolo in ambiente alcalino. Questo fatto è stato ascritto prevalentemente al miglioramento della capacità di adsorbire specie idrossido alla superficie del palladio. Lo stesso miglioramento non è stato osservato per esperimenti condotti in ambiente acido. Si sono inoltre realizzati esperimenti di ossidazione dell’etanolo su superfici di carburo di tungsteno in matrice di cobalto. Si è provato che questo materiale non mostra un’attività significativa per l’ossidazione di etanolo in ambiente alcalino. In ogni caso si è osservato che il materiale è stabile in ambienti alcalini, in un range di temperatura compreso tra 100 e 200 °C. Questo fatto unitamente all’elevata conducibilità suggerisce che il carburo di tungsteno in matrice di cobalto possa essere impiegato come supporto per la fase attiva dei catalizzatori, quali appunto il palladio. Lo stesso materiale ha mostrato una debole attività nell’ossidazione dell’etanolo ad una temperatura di 50 °C in ambiente acido. La stabilità non era però suficiente per permettere la caratterizzatione delle proprietà catalitiche in soluzioni acide a temperatura superiori.
Amongst current societal challenges sustainability is certainly a priority. The possibility of building a sustainable future, while maintaining high standards in the quality of life and preserving environment and resources, strongly relies on the availability of methods for the green production of energy and chemicals. The production of chemicals together with the on-demand power generation can be achieved in Direct Liquid Fuel Cells (DLFCs), devices in which the chemical energy of a liquid fuel is converted into electrical energy. DLFCs usually employ Small Organic Molecules (SOMs), such as alcohols or formic acid, as fuels. These fuels can be obtained from biomass feedstock. Consequently their use generates a significantly lower atmospheric CO2 with respect to the use of fossil fuels, resulting in a potential mitigation of the “greenhouse effect”. At the present stage, DLFCs rely on the use of the rare and costly platinum. This is for two reasons: i) platinum is a good catalyst for both SOMs oxidation and Oxygen Reduction Reaction (ORR); ii) platinum is stable in acidic environment. It is worth mentioning that most of DLFCs employ proton exchange membranes as electrolytes and need strongly acidic conditions for achieving low resistivity. In these systems also the water management can be a problem, as it is attracted to the cathode side for polarization and water is frequently introduced in the feed stream to the fuel cell. At present acidic DLFCs operate with a platinum content largely exceeding 1 mg cm-2, a fact that severely hampers the diffusion of such devices. In this investigation, thanks to a low resistivity Anion Exchange Membranes (AEM), the Tokuyama A-201, we have developed efficient alkaline direct liquid fuel cells (AEM-DLFCs). This has been done with the purpose of eliminating platinum from the devices. Indeed it is known that palladium effectively catalyzes SOMs oxidation in alkali; besides, oxygen reduction reaction can also be effectively achieved by using iron and cobalt phtalocyanines (Pc). Consequently the membrane electrode assembly (MEA) of a AEM-DLFC can be assembled using: i) a palladium based anode, ii) a Tokuyama A-201 membrane and iii) a cathode containing FePc-CoPc/C as electrocatalyst obtained from the high temperature pyrolysis of FePc-CoPc. An important fact is that FePc-CoPc/C is not active at all for the oxidation of SOMs. This has the major implication that fuel crossover through the membrane does not result in significant potential (and so energy efficiency) drop in fuel cells. The experimental part of this thesis starts with a chapter devoted to the analysis of the energy performance of platinum-free AEM-DLFCs fueled with ethanol (Chapter 3). This work is the first exhaustive analysis of the energy performance of such devices. Particularly we have determined the major parameters that characterize the fuel cell operations: i) maximum power density, ii) energy efficiency and iii) energy delivered per single fuel batch. All these parameters have been determined as a function of the fuel composition. We have discovered that the fuel concentration that maximizes one of the parameters can be detrimental to the others with the fundamental consequence that fuel composition must be selected according to the selected application. The effect of adding a promoting oxide, CeO2, to the anode catalyst has also been investigated. In some cases efficiency can be improved up to the 100% by simply adding cerium oxide to the anode catalyst. We have also proved that DEFCs are suitable candidates for the µ-fuel cells technology as we have shown their ability to operate with no or little performance degradation for 3 months at low power density (< 1 mW cm-2). Chapter 4 is dedicated to the Direct Formate Fuel Cells (DFFCs). Nanostructured Pd/C and FePc-CoPc/C have been employed at the anode and cathode side respectively. A large open circuit voltage (≥1.0 V) was obtained. This has been attributed to the larger (as compared with DEFCs) Nernst potential of the DFFCs and the use of FePc-CoPc/C as cathode electrocatalyst to restrain the reduction of cell voltage by fuel crossover. Our DFFCs have shown maximum power density larger than state of the art AEM-DLFCs and also Direct Formic Acid Fuel Cells (DFAFCs). AEM-DFFCs are also very effective in exploiting the energy content of the fuel. Indeed we have shown that DFFCs energy efficiency is four times the energy efficiency of analogous DEFCs. This point is very important to exploit the technology as the energy efficiency is the key issue for achieving sustainability and the major constraints for systems devoted to massive energy production. Again we have found that fuel composition is essential for the performance. The best power density was obtained by the cell fuelled with 2 M formate plus 2 M KOH, while best delivered energy, fuel utilization and energy efficiency were delivered by cell equipped with 4 M formate plus 4 M KOH. To enhance the ability of palladium to catalyze SOMs oxidation in alkaline environment, we have developed an original electrochemical treatment (Chapter 5). The treatment consisted of the application of a Square-Wave Potential (SWP) to the electrode and resulted in surface roughening and change in the distribution of the crystal surface terminations. Particularly we have found that after SWP an increase of the density of low coordination (Coordination Number < 8) Pd surface atoms occurs. We have found significant activity enhancement (from 4 to 5.6 times as compared to untreated surface) for the oxidation of all the investigated alcohols. Furthermore, FTIR spectra have shown that the reaction products distribution was also affected. Particularly we determined an increased tendency of the SWP treated Pd surface to cleave the C-C bond as compared to the untreated ones. A tailored SWP treatment for enhancing the catalytic activity of platinum was also developed (Chapter 6). The essential reason behind the study is to provide a tool for reducing Pt content in fuel cells when it cannot be completely eliminated. For platinum, it has turned out that the period of the square wave is the most important parameter. The most active platinum surface for Ethanol Oxidation Reaction (EOR) in alkali has been produced with a square wave period of 120 min, while the maximum stability of the catalytic performance has been obtained with the sample produced with a period of 360 min. Via in situ FTIR we have also found that the treated samples limit C-C cleavage as compared to the untreated ones. This suggests that SWP on Pt could provide an effective strategy to minimize the formation of CO, a major poisoning agent for platinum based catalysts. Chapter 7 is devoted to the investigation of the degradation mechanism of palladium electrocatalysts in platinum-free AEM-DLFCs. This is among the main issues still preventing the full exploitation of palladium in DLFCs. We have demonstrated that palladium oxide formation is the major cause for the catalytic performance degradation. We came to this conclusion by combining the information derived from electrochemical measurements and synchrotron light experiments (X-ray Absorption Spectroscopy). X-ray Absorption Near Edge Structure (XANES) spectra of the Pd Kα edge before and after DEFC run have shown that Pd is present in its metallic form in the pristine catalyst, while it is almost completely oxidized after work in an ethanol fed fuel cell. This has enabled us to conclude that to extend the service life of palladium electro-catalysts in alkali, the anode potential has not to exceed 0.7 V. In practice this can be achieved with a simple electronic control of the device. Increasing the operating temperature of fuel cells is an alternative strategy to improve the performance of fuel cells fed with SOMs containing fuels. In chapter 8, palladium has been investigated as a catalyst for ethanol oxidation at intermediate temperatures (> 100 °C) in a pressurized vessel. We have found that the increase of the temperature dramatically enhances the ability of catalyzing EOR in alkali. This fact has been ascribed to the improved adsorption of the hydroxyl species on the palladium surface. The same enhancement has not been observed in acidic environment. A few experiments on the use of tungsten carbide in a cobalt matrix (WC-Co) have also been performed. We have proved that WC-Co does not catalyze significantly the ethanol oxidation reaction in alkaline media, while it does in acidic electrolyte at medium temperature (~50 °C). At larger temperature the stability in acidic environment is not enough to allow a reliable assessment of the catalytic performance. Larger stability has been achieved in alkali where tungsten carbide is a potential candidate for supporting other active phases such as noble metals.
XXVII Ciclo
1987

This Thesis examines the operation and dynamic performance of a single-stage, single-switch power factor corrector, S4 PFC, with an integrated magnetic device, IM. Also detailed isthe development and analysis of a high power light emitting diode, HP LED, power factorcorrection converter and proposed voltage regulation band control approach.The S4 PFC consists of a cascaded discontinuous current mode, DCM, boost stage anda continuous current mode, CCM, forward converter. The S4 PFC achieves a high powerfactor, low input current harmonics and a regulated voltage output, utilising a singleMOSFET. A steady-state analysis of the S4 PFC with the IM is performed, identifying theoperating boundary conditions for the DCM power factor correction stage and the CCMoutput voltage regulation stage. Integrated magnetic analysis focuses on understanding theperformance, operation and generated flux paths within the IM core, ensuring the device doesnot affect the normal operation of the converter power stage. A design method for the S4 PFCwith IM component is developed along with a cost analysis of this approach. Analysis predictsthe performance of the S4 PFC and the IM, and the theoretical work is validated by MATLABand SABER simulations and measurements of a 180 W prototype converter.It is not only the development of new topological approaches that drives theadvancement of power electronic techniques. The recent emergence of HP LEDs has led to aflurry of new application areas for these devices. A DCM buck-boost converter performs thepower factor correction and energy storage, and a cascaded boundary conduction current modebuck converter regulates the current through the LED arrays. To match the useful operatinglifetime of the HP LEDs, electrolytic capacitors are not used in the PFC converter. Analysisexamines the operation and dynamic characteristics of a PFC converter with low capacitiveenergy storage capacity and its implications on the control method. A modified regulationband control approach is proposed to ensure a high power factor, low input current harmonicsand output voltage regulation of the PFC stage. Small signal analysis describes the dynamicperformance of the PFC converter, Circle Criterion is used to determine the loop stability.Theoretical work is validated by SABER and MATLAB simulations and measurements of a180 W prototype street luminaire.

There are presently worldwide targets for decreasing anthropogenic greenhouse gases (GHGs) emissions owing to global climate change concerns. Here in the United Kingdom, the government has committed to reduce its GHGs emissions by at least 80% by 2050 relative to 1990 levels. In order to achieve the ambitious 2050 targets and minimise cumulative emissions along the way, modern power systems are facing a series of great challenges. These challenges include extensive utilisation of renewable generation, diverse demand--side participation in power system operation and planning, as well as considerable application of emerging smart devices and appliances. All of these challenges will significantly increase the complexity of future power systems in terms of both operation and design. Regardless, the primary objective of power systems remains the same. That is the system must supply all the customers (responsive ones and non-responsive ones) with electricity as economically as possible and with an adequate level of continuity and quality. With the widespread utilisation of smart meters and appliances as well as the large-scale installation of different storage technologies, the services that demand response (DR) and electrical energy storage (EES) resources can provide will cover a wide range of ancillary services. More importantly, the grid-scale penetration of DR and EES resources is able to provide energy management and capacity support services, which can be considered as the alternative to generation resources. In this light, considerable amount of research has been done focusing on engaging particular types of electricity users with different kinds of incentives and/or tariff schemes, so that the economic benefits to both utilities and customers are optimised. However, no general framework for systematic assessment of the contribution to power system adequacy of supply from potential grid-scale penetration of DR and EES resources is available up till now, particularly taking specific consideration of DR's flexibility and payback characteristics as well as EES's operational parameters. The research work in this thesis therefore emphasises exclusively on the potential of grid-scale DR and EES resources to serve as alternative resources to electricity generation within the context of power system adequacy of supply. More specifically, based on literature survey of existing studies in similar topics, this thesis has made some substantial contributions and innovations, such as developing novel models of these emerging demand-side resources, implementing a systematic adequacy of supply assessment with new aspect to measure the level of adequacy of supply (new indices), proposing a novel and comprehensive framework for evaluation of the capacity credit of DR and EES, and analysing the economic value based on power system fundamental long--term costs of interruption and supply. Ultimately, this thesis has established a comprehensive framework for assessment of the contribution of DR and EES to power system adequacy of supply. Additionally, the numerical studies carried out in this thesis have enabled the inference of general adequacy of supply implications in terms of deploying DR and EES resources to provide capacity support to power systems.

碩士
崑山科技大學
電子工程研究所
94
In this thesis, we propose two novel power integrated circuits (ICs): high-voltage and multiple-voltage, and fabricate them in TSMC 0.35-μm 2P4M CMOS process for portable device application. High-voltage power IC is mainly composed of new charge pump circuits. In order to achieve fewer output stages and larger output voltage, we employ the charge transfer switches and the complementary structure to design the positive high-voltage charge pump circuit. On the other hand, for negative high-voltage power IC, we use bulk driven technique. The measurement results show that the output voltages of positive and negative high-voltage charge pump circuits are 7.98 V and -8 V at the input frequency of 1 MHz. Multiple-voltage power IC contains a low dropout (LDO) linear regulator, a bandgap reference, and two improved charge pump circuits. To design the improved charge pump circuits, we use layout technique to ensure the reliability of MOS under high voltage and PMOS diode charge transfer devices. Under the condition of load capacitance of 500 pF, the positive high output voltage is 14 V and negative one is -10 V in post-layout simulation. Under the condition of the 3.3 V input voltage, the output of LDO regulator is 1.8 V and the maximum output load current is up to 150 mA.

碩士
國立成功大學
電機工程學系碩博士班
97
This thesis presents the design of contactless power supply pad for low power portable multimedia electric appliances, such as electronic papers, PDA, smart phone or MP4. First, the fundamental principle and application fields of contactless power transmission are discussed, and the circuit topology and the coupling structure which this system adopts are proposed. Since the contactless power transmit ability is restricted by leakage inductance, thus the design of the resonant circuit can improve the characteristic of impedance and the system performance. In order to employ pad effectively, microcontroller is utilized to implement selective excitation circuit and switching frequency circuit. Experimental results show that the power transmission efficiency of contactless inductive structure is 72% under 30mm gap.

碩士
國立清華大學
電機工程學系
96
Ozone has strong sterilization capability and does not cause re-pollution to the environment. However, since it has a short half-life, meaning that it deoxidizes into oxygen in a short time span, makes it impossible to be put in mass production and store in containers. Hence, for small scale applications like in domestic use, a miniaturized ozone generator would be very convenient. The dielectric barrier ozone generator is one of the quietest types among all discharge ozone generators. Therefore, the main purpose of this thesis is focused to design and implement a high voltage power supply for miniaturized portable dielectric barrier discharge (also called the silent discharge) ozone generators for the use in indoor environments. Basically, the contributions of this thesis can be summarized as follows. First, propose a high voltage power supply for silent discharge ozone generators used for indoor applications and miniaturization demands. The high voltage power supply consists of two stages. The front stage is a boost-type power factor correction circuit to achieve low current harmonics and high power factor. The second stage is a half-bridge high frequency series-parallel resonant inverter with zero-voltage switching to achieve less voltage stress and higher efficiency. Second, some design criteria are given for designing the high voltage power supply by employing the high frequency equivalent circuit model of the ozone generator together with a burst mode control to achieve more robust output voltage under changing loads. Finally, a high voltage power supply with 80~270Vac 60Hz input, 2kVac 300kHz output, and 500W rated power is actually implemented. The power factor of the front stage PFC is 0.95~0.99, and the highest efficiency may reach 96%. The second stage high voltage inverter can achieve an efficiency of 87% approximately. It turns out that the overall efficiency can reach 83.5%. Also, it is seen that the constructed prototype can indeed achieve the expected performance.

This Master of Applied Science thesis proposes a new design of low power, power factor corrected (PFC), power supplies. By lifting the hold up time restriction for devices that have a battery built in, the energy storage elements of the converter can be reduced, permitting a small and inexpensive power converter to be built. In addition, a new control technique for controlling cascaded converters is presented, named duty mode control (DMC). Its advantages are shown through simulations. The system was proven using a prototype developed in the laboratory designed for a universal ac input voltage (85 - 265VRMS at 50 - 60Hz) and a 40W output at 12V. It consisted of two interleaved phases sensed and digitally controlled on the isolated side of the converter. The prototype was able to achieve a power factor of greater than 0.98 for all operating conditions, and input harmonic current distortion well below any set of standards.

AbstractCOVID-19 has brought to light the multiple cracks in the logistically integrated, financialized and commodity-based capitalist food system. As with other aspects of social life thrown into disruption amid the global health, economic and environmental downturn, the early weeks of the pandemic seemed to offer the hope of transformative possibility, a “portal” towards different food systems. The time seemed ripe for the kinds of radical transitions that social movements and peasants’ organizations have requested for decades: subverting the “conventional” food system without going back to “corporate normality”. However, when the multiple crises are characterized as exceptional rather than structural, a narrative of emergency and urgency is deployed to reinforce the power of the incumbents. The overlap between the pandemic and the climate crisis can be an opportunity, but hardly for peasants and indigenous people. As in Naomi Klein’s Shock Doctrine, corporate actors and billionaire philanthropists are using the rhetoric of urgency to push for changes that reinforce the status quo and do not address the root causes that have brought us here. In order to spark debate and reflections, my contribution engages with one example of ongoing co-optation of the state of climate and sanitary emergency: the 2021 United Nations Food Systems Summit as a new food policy arena where decisions are distanced from peasants, indigenous communities and citizens and put in the hands of corporations, financial investors and billionaire philanthropists.

Electronic portable devices present some technological challenges like battery life, providing services, and integration of renewable power supplies. These challenges can be improved using power management based solutions. Power management systems for electronic portable devices are ad-hoc solutions for each device, so solutions are not general enough to be applied to others. A model driven architecture approach is defined. It allows defining a general power management systems solution for portable devices. The general solution is based on agent modelling, which is parameterized, so it allows automatic retrieval of the power management multi-agent system for a particular device giving values to the model’s parameters. Distributed management strategies are based on giving priority to renewable power sources and reducing power spikes when there is not enough power. A laptop equipped with a photovoltaic charger is introduced for simulating power demand and supply in order to discuss power management strategies for reducing electrical consumption.

Ultra-low-power strategies have a huge importance in today's integrated circuits designed for internet of everything (IoE) applications, as all portable devices quest for the never-ending battery life. Dynamic voltage and frequency scaling techniques can be rewarding, and the drastic power savings obtained in subthreshold voltage operation makes this an important technique to be used in battery-operated devices. However, unpredictability in nanoscale chips is high, and working at reduced supply voltages makes circuits more vulnerable to operational-induced delay-faults and transient-faults. The goal is to implement an adaptive voltage scaling (AVS) strategy, which can work at subthreshold voltages to considerably reduce power consumption. The proposed strategy uses aging-aware local and global performance sensors to enhance reliability and fault-tolerance and allows circuits to be dynamically optimized during their lifetime while prevents error occurrence. Spice simulations in 65nm CMOS technology demonstrate the results.

The demand for portable device applications has grown immensely. For such applications, low voltage and low power operation is an essential prerequisite to prevent overheating and ensure reliable functioning. Low voltage operation curtails the total number, weight, and dimensions of batteries, and low power consumption extends battery life. The shrinking size of MOS transistors in CMOS processes necessitates the use of lower supply voltages. Since the threshold voltage of MOS transistor is not diminished at the same rate as the power supply voltage, analog designers face problems due to shrinking voltage headroom. One of the findings that can overcome the issues introduced by comparably high threshold voltages is based on the enactment of body bias approach. In such a solution, a relatively small potential is applied at body terminal of a MOS transistor to adjust its threshold voltage. This chapter discussed that body bias approach is an attractive opportunity for utilizing the body effect positively to improve the performance of low voltage-integrated circuits.

There has been a renewed interest in the development of surface acoustic wave (SAW) biosensors because they hold great promise for opening new frontiers in biology and medicine. The promise of SAW technology is grounded in the advantages SAW devices hold over traditional laboratory techniques used in biological and medical laboratories. These advantages include having smaller sizes to allow greater portability, using smaller sample volumes, requiring lower power requirements, the ability to integrate them into microfluidic platforms, and their compatibility with smart devices such as smartphones. The devices offer high sensitivity and can be designed to allow microfluidic interfacing. Other major advantages of SAW-based technologies include the fact that they can be operated remotely in harsh conditions without the need for an AC power supply. Their compatibility with lab-on-a-chip systems allows the creation of fully integrated devices with the ability to isolate the sample from the operator. In this mini-review, we will discuss SAW devices and their ability to enable a variety of applications in Biology and Medicine. The operating principles of the SAW biosensors will be discussed along with some technological trends and developments.

Abstract Thermophotovoltaic (TPV) energy conversion, which uses photovoltaic (PV) cells to directly convert radiant thermal energy into electric power, has a number of important advantages for portable power generation in military applications. Since TPV is a direct energy conversion technology with no moving parts in the energy conversion system, it has the potential to provide quiet, reliable, maintenance-free electric power for thousands of hours. These systems also have the potential to be as efficient as small portable engine generators, operate on military logistic fuels, and start and operate in sub-freezing environments. A 150 Watt thermophotovoltaic (TPV) power module has been designed, built, and tested. The technical approach taken in the design focused on optimizing the integrated performance of the primary subsystems in order to yield high energy conversion efficiency and cost effectiveness. An important aspect of the approach is the use of a narrow band fibrous emitter radiating to a bandgap matched photovoltaic array to minimize thermal and optical recuperation requirements, as well as the non-recoverable heat losses. For the prototype system, fibrous ytterbia emitters radiating in a narrow band centered at 980 nm are matched with high efficiency silicon photoconverters. The integrated system includes a dielectric stack filter for optical energy recovery and a ceramic recuperator for thermal energy recovery. The prototype TPV system uses a rapid mix distributed fuel delivery system with controlled feeding of the fuel and heated air into a flame at the surface of the emitter. This makes it possible to operate at air preheat temperatures well above the auto-ignition temperature of the fuel thereby substantially increasing the system efficiency. The system has been operated with air preheat temperatures up to 1367 K and has produced a uniform narrow band radiation over the surface of the emitter with this approach. The design of the system is described and test data for the system and some of the key components are presented. The results from a system model, which show the impact of various parameters on system performance, are also discussed.