3,060 research outputs found

    Local control of multiple module converters with ratings-based load sharing

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    Multiple module dc-dc converters show promise in meeting the increasing demands on ef- ficiency and performance of energy conversion systems. In order to increase reliability, maintainability, and expandability, a modular approach in converter design is often desired. This thesis proposes local control of multiple module converters as an alternative to using a central controller or master controller. A power ratings-based load sharing scheme that allows for uniform and non-uniform sharing is introduced. Focus is given to an input series, output parallel (ISOP) configuration and modules with a push-pull topology. Sensorless current mode (SCM) control is digitally implemented on separate controllers for each of the modules. The benefits of interleaving the switching signals of the distributed modules is presented. Simulation and experimental results demonstrate stable, ratings-based sharing in an ISOP converter with a high conversion ratio for both uniform and non-uniform load sharing cases

    Requirements for Power Converters

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    This paper introduces the requirements for power converters needed for particle accelerators. It describes the role of power converters and the challenges and constraints when powering magnets. The different circuit layouts are presented as well as the operating cycles. The power converter control and high precision definition are also introduced. This paper lists the key circuit parameters to be taken into consideration to properly specify a power converter that can be compiled in a functional specification.Comment: 14 pages, contribution to the 2014 CAS - CERN Accelerator School: Power Converters, Baden, Switzerland, 7-14 May 201

    Distributed control of a fault tolerant modular multilevel inverter for direct-drive wind turbine grid interfacing

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    Modular generator and converter topologies are being pursued for large offshore wind turbines to achieve fault tolerance and high reliability. A centralized controller presents a single critical point of failure which has prevented a truly modular and fault tolerant system from being obtained. This study analyses the inverter circuit control requirements during normal operation and grid fault ride-through, and proposes a distributed controller design to allow inverter modules to operate independently of each other. All the modules independently estimate the grid voltage magnitude and position, and the modules are synchronised together over a CAN bus. The CAN bus is also used to interleave the PWM switching of the modules and synchronise the ADC sampling. The controller structure and algorithms are tested by laboratory experiments with respect to normal operation, initial synchronization to the grid, module fault tolerance and grid fault ride-through

    High Efficiency LED Drivers: A Review

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    Recently various soft switching techniques have been developed for various DC-DC based LED drivers. Typical driver circuits in the market have efficiency between 80% - 95% with majority having efficiency between 80% - 90%. Various topologies and strategies are available to obtain the best performance. A comparison and discussion of different buck and floating buck topologies used as driver in LED lighting application are presented in this paper

    Design and development of power processing units for applications in electrically-propelled satellite systems

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    Electrospray technology provides a way to ionize specialized liquids by applying high voltages across a sharp porous tip and a metallic mesh. This technology is widely used in the field of mass spectroscopy for generating ions for testing purposes. The dawn of nano-satellites posed new challenges in the miniaturization of many conventional satellite sub-systems. One significant challenge faced in such a process was the miniaturization of the propulsion system. Electrosprays have started to find their application in the field of Aerospace Engineering and now are formally known as Electrospray Thrusters. These thrusters provide high specific impulse and are attractive substitutes to conventional gas propelled thrusters as they can be scaled down in size and can also provide extended mission times. Some of the new challenges faced in such applications are the generation of high voltages from a low voltage onboard battery, grounding, spacecraft charging, clearance, and reliability issues for long term usage. In this work, a complete design process is developed for the realization of such high voltages suitable for interfacing with an electrospray thruster. Simulation models for a new type of converter are assessed, and its feasibility is discussed. A hardware prototype is implemented, and the practical results are assessed. An analysis of the converter is presented, and the semiconductor and passive components are selected. Magnetic components are designed based on the analysis. Parallels are drawn between the theoretical and prototype model of the concept converter. Finally, the firmware of the converter is explained, and the communication protocol of the PPU is delineated. As the boards designed for the converter have to sustain high voltages and reliably operate in unfavorable environments, special PCB layout considerations must be used, which also forces a designer to look for various other materials for the PCB fabrication --Abstract, page iv

    Development of a four phase floating interleaved boost converter for photovoltaic systems

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    This paper explores the advantages of the Floating Interleaved Boost Converter, particularly with regards to solar photovoltaic power systems. This converter offers improved efficiency and voltage gain, while having lower input current ripple than other DC-DC boost converters. An analog linear feedback controller was developed, and adapted for discrete control. Two Maximum Power Point Tracking methods were explored, and their performances were evaluated in simulation. An experimental prototype was developed and demonstrated. The results show that this is a promising converter topology with many potential benefits for solar power applications

    A Hardware-in-the-Loop Platform for DC Protection

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    With the proliferation of power electronics, dc-based power distribution systems can be realized; however, dc electrical protection remains a significant barrier to mass implementation dc power distribution. Controller Hardware-in-the-loop (CHiL) simulation enables moving up technology readiness levels (TRL) quickly. This work presents an end-to-end solution for dc protection CHiL for early design exploration and verification for dc protection, allowing for the rapid development of dc protection schemes for both Line-to-Line (LL) and Line-to-Ground (LG) faults. The approach combines using Latency Based Linear Multistep Compound (LB-LMC), a real-time simulation method for power electronic, and National Instruments (NI) FPGA hardware to enable dc protection design with CHiL. A case study is performed for a 1.5 MW Voltage Source Rectifier (VSR) under LL and LG faults in an ungrounded system. The deficiency in real-time simulation resolution of Commercial-off-the-Shelf (COTS) for dc fault transients is shown, and addressed by using LB-LMC RT solver inside NI FPGA hardware to achieve 50 ns resolution of dc fault transients
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