Overview of Power Electronic Converter Topologies Enabling Large-Scale Hydrogen Production via Water Electrolysis

Renewable power-to-hydrogen (P2H) technology is one of the most promising solutions for fulfilling the increasing global demand for hydrogen and to buffer large-scale, fluctuating renewable energies. The high-power, high-current ac/dc converter plays a crucial role in P2H facilities, transforming medium-voltage (MV) ac power to a large dc current to supply hydrogen electrolyzers. This work introduces the general requirements, and overviews several power converter topologies for P2H systems. The performances of different topologies are evaluated and compared from multiple perspectives. Moreover, the future trend of eliminating the line frequency transformer (LFT) is discussed. This work can provide guidance for future designing and implementing of power-electronics-based P2H systems

High-Efficiency Three-Phase Current Source Rectifier Using SiC Devices and Delta-Type Topology

In this dissertation, the benefits of the three-phase current source rectifier (CSR) in high power rectifier, data center power supply and dc fast charger for electric vehicles (EV) will be evaluated, and new techniques will be proposed to increase the power efficiency of CSRs. A new topology, referred as Delta-type Current Source Rectifier (DCSR), is proposed and implemented to reduce the conduction loss by up to 20%. By connecting the three legs in a delta type on ac input side, the dc-link current in DCSR can be shared by two legs at the same time. To increase the switching speed and power density, all-SiC power modules are built and implemented for CSRs. The switching waveforms in the commutation are measured and studied based on double pulse test. Four different modulation schemes are compared for high efficiency CSR considering the switching characteristics of different device combinations. The most advantageous modulation scheme is then identified for each of the device combinations investigated. A compensation method is proposed to reduce the input current distortion caused by overlap time and slow transition in CSRs. The proposed method first minimizes the overlap time and then compensates the charge gain/loss according to the sampled voltage and current. It is verified that the proposed method can reduce the input current distortion especially when the line-to-line voltage is close to zero. The dc-link current will become discontinuous under light load in CSRs, when the traditional control algorithm may not work consistently well. To operate CSR in discontinuous current mode (DCM), the CSR is modeled in DCM and a new control algorithm with feedforward compensation is proposed and verified through experiments. A protection scheme with fast response time is proposed, analyzed and verified to protect SiC devices from overvoltage caused by current interruption in CSRs. To deal with the harmonics and voltage sag in the input ac voltage, a new control algorithm is proposed. By adding ac current feedback control and proportional-resonant (PR) control, the proposed control algorithm can reduce the input current distortion and dc output voltage ripple under input voltage disturbance

Bi-directional Current-fed Medium Frequency Transformer Isolated AC-DC Converter

The use of high power converters has increased tremendously. Increased demand for transportation, housing and industrial needs means that more number of power converters interact with the utility power grid. These converters are non-linear and they draw harmonic currents, significantly affecting power quality. To reduce harmonics, filters, power factor correction circuits and capacitor banks are required. And the development of hybrid technologies and renewable energy power stations trigger a demand for power converters with bi-directional capabilities. The objective of this thesis is to develop a high power quality, bi-directional AC-DC power converter that is a solution to the aforementioned problems. This thesis studies an existing topology for a high power AC-DC power conversion with transformer isolation. The topology consists of an uncontrolled rectifier followed by a DC-DC converter to produce a set voltage output. A design example of the topology is simulated using the PSIM software package (version 6). Critical performance characteristics such as power factor and total harmonic distortion are analyzed. Following that study a new topology is proposed, which is an improvement over the older design, with reduced power conversion stages. The new topology has a fully controlled current source Pulse Width Modulation (PWM) rectifier at the front end to replace the uncontrolled rectifier and DC-DC combination. This topology has multiquadrant operational capabilities and the controller employs Selective Harmonic Elimination techniques to produce the programmed PWM switching functions for the rectifier. A design example of the converter and the digital controller are simulated in PSIM environment. The converter input current THD (Total Harmonic Distortion) and input power factor are within IEEE 519 and DoE standards. The converter is simulated in both first and fourth quadrant operations. A side-by-side comparison of the two topologies is done with respect to design and performance features such as power factor, THD, filter size, etc. The new topology converter provides performance superior to that of the older topology. Finally the thesis explores possible applications for the converter in power supplies, renewable energy and hybrid technologies

Analysis of DC and AC Choke Effects on Common-Mode Noise Emissions in ASD at the Frequency Range of 9–150 kHz

Magnetic chokes are conventionally utilized at the DC or AC side of the Adjustable Speed Drives (ASDs) to suppress low order harmonics of 0-2 kHz. Recently, the frequency range of 9-150 kHz has been noticed as a new disturbing frequency range, interfering with the distribution networks. Due to the novelty of this topic, so far, there has not been a thorough investigation for the effect of DC and AC choke configurations on 9-150 kHz emissions, especially for the three-phase ASDs. In this paper, the effect of DC and AC choke configurations on Common-Mode (CM) current emissions at the frequency range of 9-150 kHz is broadly surveyed in the three-phase ASDs. Subsequently, the comprehensive equivalent models of the system are presented for each configuration of DC and AC chokes. This investigation is based on the comparative analysis of the system's transfer functions according to the presented single-phase equivalent model, mathematical calculations, and the three-phase system circuit. Consequently, the presented approach is highly useful to minimize the drive system volume, as the designer can predict the choke configuration of the smallest size for suppressing 9-150 kHz emissions.</p

Power and Energy Student Summit 2019: 9 – 11 July 2019 Otto von Guericke University Magdeburg ; Conference Program

The book includes a short description of the conference program of the "Power and Energy Student Summit 2019". The conference, which is orgaized for students in the area of electric power systems, covers topics such as renewable energy, high voltage technology, grid control and network planning, power quality, HVDC and FACTS as well as protection technology. Besides the overview of the conference venue, activites and the time schedule, the book includes all papers presented at the conference

Enhanced electrodeposition for the filling of micro-vias

This thesis investigated the introduction of megasound (MS) (1MHz) acoustic technology as an enhanced agitation method of an electrolyte solution for the electrochemical deposition of copper (Cu), used in electroplating processes. The thesis, carried out at Merlin Circuit Technology Ltd, studied the possibility of improving processing capabilities for use in Printed Circuit Board (PCB) industrial manufacture. Prior laboratory experiments demonstrated increased metallisation of vertical interconnect access (via) features in a Printed Circuit Board (PCB), which, if applied within manufacturing, would enable increased connectivity throughout a PCB and result in cost savings. PCB manufacturing quality after MS-assisted Cu electroplating was assessed by measurements of the topography of the electrodeposits, using scanning electron microscopy and white-light interferometry. Cu plating rate changes were also measured on the surface of the PCB and inside the vias. After plating Cu with MS-assistance, the macro and microscale surface composition was demonstrated to alter due to the direct influence of the acoustic waves. Systematic characteristic of the surface was conducted by varying the settings of the acoustic transducer device as well as the process parameters including electrical current distribution, bath additive chemistry and solution temperature. MS processing was shown to produce unique Cu artefacts. Their deleterious formation was demonstrated to be influenced by acoustic standing waves and microbubble formations at the electrolyte solution/PCB interface. Causes of these artefacts, microfluidic streaming and cavitation, were also observed and controlled to reduce the creation of these artefacts. MS plating Cu down through-hole via (THV) and blind-via (BV) interconnects was shown to produce measureable benefits. These include, for THVs, a 700 % increase of Cu plating deposit thickness within a 175 μm diameter, depth-to-width aspect ratio (ar) of 5.7:1, compared with processing under no-agitation conditions. For BVs, a 60 % average increase in Cu deposition in 150 μm and 200 μm, ar 1:1, was demonstrated against plating under standard manufacturing conditions - bubble agitation and panel movement.Engineering and Physical Research Council (EPSRC) grant number EP/G037523/

Characterisation of 3.3kV IGCTs for Medium Power Applications

Le développement des IGCT Basse Tension (3,3kV) vise un composant capable de travailler à fréquence élevée (>1 kHz) tout en gardant sa capacité « fort courant » (4kA). L'objectif final est d'augmenter les performances dynamiques des convertisseurs moyenne/forte puissance et d'étendre ainsi leur champ d'application. Pour la caractérisation des échantillons expérimentaux des IGCT 3,3kV, un banc d'essais basé sur une méthode d'opposition a été développé. Cette méthode permet l'évaluation des composants sous différentes conditions d'essai en mode de fonctionnement réel sans nécessité de sources d'alimentation de plusieurs MW. Une fois les échantillons caractérisés, l'analyse de l'applicabilité de ces composants dans des applications spécifiques aux réseaux ferroviaires SNCF est abordée. Finalement, une application de compensation de puissance réactive pour des réseaux monophasés a été étudiée en détail et une maquette de 100kVAR à base de IGCTs a été réalisée. ABSTRACT : The Low Voltage IGCT (3.3kV) is developed to provide a semiconductor able to work at high switching frequencies (>1kHz), preserving its « high current » capacity (4kA). The ultimate goal is to increase the dynamic performances of medium/high power converters, thus extending their application field. To characterise the experimental samples of 3.3kV IGCTs, an opposition method based test bench was developed. This method allows the components to be evaluated at different test conditions in real operation without the need of several megawatt power supplies. Once the samples were characterised, the applicability analysis of these components on specific applications related to the French railway network (SNCF) is performed. Finally, a reactive power compensation application for single-phase systems is studied in detail and a 100kVAR IGCT based set up is built

Renewable Energy

Renewable Energy is energy generated from natural resources - such as sunlight, wind, rain, tides and geothermal heat - which are naturally replenished. In 2008, about 18% of global final energy consumption came from renewables, with 13% coming from traditional biomass, such as wood burning. Hydroelectricity was the next largest renewable source, providing 3% (15% of global electricity generation), followed by solar hot water/heating, which contributed with 1.3%. Modern technologies, such as geothermal energy, wind power, solar power, and ocean energy together provided some 0.8% of final energy consumption. The book provides a forum for dissemination and exchange of up - to - date scientific information on theoretical, generic and applied areas of knowledge. The topics deal with new devices and circuits for energy systems, photovoltaic and solar thermal, wind energy systems, tidal and wave energy, fuel cell systems, bio energy and geo-energy, sustainable energy resources and systems, energy storage systems, energy market management and economics, off-grid isolated energy systems, energy in transportation systems, energy resources for portable electronics, intelligent energy power transmission, distribution and inter - connectors, energy efficient utilization, environmental issues, energy harvesting, nanotechnology in energy, policy issues on renewable energy, building design, power electronics in energy conversion, new materials for energy resources, and RF and magnetic field energy devices