This thesis presents a microbattery recharging circuit suitable for autonomous microsystems. The battery charger chosen for this design is a constant current battery charger. Two methods of regulating the constant-current are discussed. A published shunt regulator design is analyzed and is presented with enhancements to the design. A series regulator that controls the current to the battery with a switch is designed and fabricated in a 1.5µm CMOS process. The fabricated prototype occupies less than 2.20x2.20mm and is expected to dissipate less than 25µW of power. A discrete model of the integrated circuit is constructed and tested to demonstrate that the series regulator will work using a solar cell as the energy source. The design of the charger is a major step toward the construction of a completely integrated autonomous system.

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No description available.

Recently, as a promising lighting source, light-emitting diodes (LEDs) have become more and more attractive and have great opportunity to replace traditional lighting sources - incandescent, fluorescent and HID because of the advantages such as high luminous efficacy, long lifetime, quick on/off time, wide color gamut, eco-friendly etc. Based on the research from U.S. Department of Energy, over 30% of total electric consumption in U.S. each year is for lighting, 75% of which are for indoor lighting (including both residential and commercial buildings). In the indoor LED lighting application, to provide multiple current source outputs for multiple LED strings, traditional solutions usually adopt a two-stage structure, which is complicated and cost-ineffective. How to design a simple, low-cost and efficient LED driver with multiple current source outputs is in great demand and really challenging. In this thesis, a single-stage multi-channel constant current (MC3) LED driver structure has been proposed. Multiple transformer structure is utilized to provide multiple current source outputs. The current control scheme is also simple - only one LED string current is sensed and controlled; other strings' currents are cross regulated. Firstly, a PWM half bridge topology is chosen to implement the proposed single-stage MC3 LED driver concept. In order to analyze the current cross regulation, a general model is derived. The circuit has been simulated under various LED load conditions to verify its good current sharing capability. In order to further improve efficiency, simplify the driver's complexity and reduce cost, a LLC resonant topology is also investigated. LLC current gain characteristic has been derived by considering LED's i-v character and a design procedure is developed. A 100 kHz, 200 W, 4-string MC3 LLC LED driver is designed and tested. The experimental results show that the driver can maintain constant current output within the whole input and output variations, achieve good efficiency and realize current sharing under both balanced and unbalanced LED conditions. The dimming function can also be realized through frequency modulation method and burst mode control method. As a conclusion, a single-stage MC3 LED driver concept is proposed and implemented with two topologies. The proposed idea provides a simple, low-cost and efficient solution for indoor LED lighting application with multiple LED string configuration. It also has good current sharing capability and robustness to LED forward voltage variations or short failures. / Master of Science

É apresentado neste trabalho um novo método de carga de filmes dielétricos com descarga corona, no qual a corrente de carga da amostra é mantida constante durante a deposição dos íons, enquanto o potencial de superfície é medido pela técnica do capacitor vibrante. O método foi aplicado no estudo de transporte e armazenamento de portadores em polímeros, principalmente no Teflon FEP e PVDF. No Teflon FEP carregado com corona positiva e negativa, a superfície do material exerce um papel predominante. O transporte de elétrons é dominado pelos traps de volume. Para a corona positiva a injeção é controlada pelo trapping e detrapping das armadilhas superficiais. No PVDF os resultados obtidos são razoavelmente independentes da polaridade da descarga corona. Para baixos campos elétricos o potencial de superfície parece ser determinado pela condutividade do material, perturbado pela existência de uma polarização de volume. / A new method of charging dielectric films with corona current is presented here, the sample charging current being keept constant during the deposition, while the surface potential is measured by vibrating capacitor technique. The method was applied to study the carrier transport and storage in polymers, mainly in Teflon FEP and PVDF. For positive and negative corona in Teflon FEP, the surface plays an important role. The electron transport is dominated by bulk traps. For positive corona injection into the volume is controlled by surface trapping and detrapping. For PVDF the results are almost independent of the current polarity. For low electrical fields, the results indicate that the surface potential is determined by the material conductivity, perturbed by the build up of a bulk polarization.

<p>Vid idrifttagning av banljussystemet på Bana 3, Arlanda flygplats, uppstod vissa driftsproblem. Problemen yttrade sig så att de regulatorer, så kallad CCR (Constant Current Regulator), som försörjer informations- och anvisningsskyltar, löste ur för framförallt överström. Det berodde på att kretsen var ovanligt oscillativ. Problemen uppstod enbart på de kretsar som hade skyltar som last. Som belysning i skyltarna används lysrör. </p><p>Kretsen skiljer sig från vanliga belysningssystem på det viset att det är en seriekrets. Seriesystemet har flera fördelar jämfört med ett traditionellt parallellsystem, bland annat att det är billigare och enklare att bygga. Det gör då att istället för en konstant spänning finns en konstant ström att tillgå i kretsen. Detta gör att man måste omvandla strömmen till en konstant spänning, för att kunna driva lysrören. Vanliga lampor är inte beroende av en konstant spänning för att lysa. </p><p>Rapporten presenterar hur en seriekrets är uppbyggd och vad det finns för komponenter i just denna anläggning på Arlanda. Vidare presenteras funktionen för de olika komponenterna, och hur de påverkar omgivningen. </p><p>Utförda mätningar på Arlanda används, tillsammans med information från tillverkare, som grund för en analys av systemet. Utgående från resultatet av denna analys presenteras förslag på åtgärder.</p>

In recent years, smart gird has received much attention, and many researchers have devoted to home area network (HAN) to improve the efficiency of grid. This thesis proposes a bidirectional isolated DC-DC converter (Dual Active Bridge, DAB) with phase shift control to implement the concept of HAN. Li+Fe battery is used as storage device of the converter, and a bidirectional communication between Laboratory Virtual Instrumentation Engineering Workbench (LabVIEW) and Digital Signal Processor (DSP) is realized by CAN-bus. By setting the current command given by LabVIEW system, the converter is able to charge the Li+Fe battery with constant current and constant voltage method as well as discharge the Li+Fe battery with constant current. Operation principle of the converter and the associated loss are presented.

É apresentado neste trabalho um novo método de carga de filmes dielétricos com descarga corona, no qual a corrente de carga da amostra é mantida constante durante a deposição dos íons, enquanto o potencial de superfície é medido pela técnica do capacitor vibrante. O método foi aplicado no estudo de transporte e armazenamento de portadores em polímeros, principalmente no Teflon FEP e PVDF. No Teflon FEP carregado com corona positiva e negativa, a superfície do material exerce um papel predominante. O transporte de elétrons é dominado pelos traps de volume. Para a corona positiva a injeção é controlada pelo trapping e detrapping das armadilhas superficiais. No PVDF os resultados obtidos são razoavelmente independentes da polaridade da descarga corona. Para baixos campos elétricos o potencial de superfície parece ser determinado pela condutividade do material, perturbado pela existência de uma polarização de volume. / A new method of charging dielectric films with corona current is presented here, the sample charging current being keept constant during the deposition, while the surface potential is measured by vibrating capacitor technique. The method was applied to study the carrier transport and storage in polymers, mainly in Teflon FEP and PVDF. For positive and negative corona in Teflon FEP, the surface plays an important role. The electron transport is dominated by bulk traps. For positive corona injection into the volume is controlled by surface trapping and detrapping. For PVDF the results are almost independent of the current polarity. For low electrical fields, the results indicate that the surface potential is determined by the material conductivity, perturbed by the build up of a bulk polarization.

Vid idrifttagning av banljussystemet på Bana 3, Arlanda flygplats, uppstod vissa driftsproblem. Problemen yttrade sig så att de regulatorer, så kallad CCR (Constant Current Regulator), som försörjer informations- och anvisningsskyltar, löste ur för framförallt överström. Det berodde på att kretsen var ovanligt oscillativ. Problemen uppstod enbart på de kretsar som hade skyltar som last. Som belysning i skyltarna används lysrör. Kretsen skiljer sig från vanliga belysningssystem på det viset att det är en seriekrets. Seriesystemet har flera fördelar jämfört med ett traditionellt parallellsystem, bland annat att det är billigare och enklare att bygga. Det gör då att istället för en konstant spänning finns en konstant ström att tillgå i kretsen. Detta gör att man måste omvandla strömmen till en konstant spänning, för att kunna driva lysrören. Vanliga lampor är inte beroende av en konstant spänning för att lysa. Rapporten presenterar hur en seriekrets är uppbyggd och vad det finns för komponenter i just denna anläggning på Arlanda. Vidare presenteras funktionen för de olika komponenterna, och hur de påverkar omgivningen. Utförda mätningar på Arlanda används, tillsammans med information från tillverkare, som grund för en analys av systemet. Utgående från resultatet av denna analys presenteras förslag på åtgärder.

This diplom thesis theoretically deals about principle of pulse welding current source. Work explains operation principle of the single acting transmit converter used in realized construction and mention the others examples of converters types. Goal of the work is design individual parts of source : input filter, pulse transformer, output inductor and power semiconductors components. Thesis also contains description of the regulation circuitry of the converter, auxiliary power supply and pre-driver for power transistors. If everything will be all right prototype of the source will be assembled and measured. Results will be compared with theoretical assumptions.