Study of power conditioning system of superconducting magnetic energy storage system

A Superconducting Magnetic Energy Storage System (SMES) can be utilized for the compensation of nonlinear and pulsating loads. In this paper a power conditioning system (PCS) is designed to achieve SMES to work as a shunt active power filter and power conditioner at the same time. Two Hysteresis band controllers have been implemented to obtain (i) a sinusoidal input source current in phase with fundamental component of line to neutral source voltage irrespective of the load conditions (ii) Charging and discharging of SMES under constant voltage control mode. DC link voltage is kept constant by DC/DC Bidirectional Converter and source current is controlled by Voltage Source Converter (VSC). The magnitude of reference source current is obtained by controlling the energy of SMES by using Fuzzy Logic Controller (FLC). As it is a nonlinear controller it gives better performance than previously used PI controller in parameter variations and load disturbances. Analysis of the circuit operation under Fuzzy controller is presented in detail. Simulation has been done in MATLAB/Simulink and results are presented demonstrating the feasibility of the proposed power conditioning system

Isolated and Bidirectional DC-DC Converter for Electric Vehicles

O estado da arte iniciou com a análise na literatura de topologias de conversores DC-DC. Técnicas de modulação são estudadas com vista a melhorar a eficiência de conversão, realçando as vantagens e limitações inerentes das mesmas. Após a análise da literatura, o foco projeto passou a ser a topologias de dupla ponte com dispositivos ativos e com isolamento galvânico intermédio entre as duas pontes (conhecido em inglês por dual active bridge). Algumas técnicas de modulação que permitem o funcionamento do conversor são analisadas no documento e suportadas com resultados obtidos em ambiente de simulação. O dimensionamento do transformador de potência é realizado assim como a descrição dos passos. É relizado uma análise de mercado de dispositivos de comutação com a tecnologia "Silicon Carbide" e são apresentados estimativas de perdas e eficiência de operação na utilização de transistores com a techonoloa SiC no conversor analisado. Os resultados são obtidos com recurso a simulações computacionais que através de modelos de aproximação permitem aproximar o conversor a uma situação mais proxima da real. Em termos de implementação, é esperado a implementação um circuito de comando para dois MOSFETS com tecnologia SiC com a configuração em meia ponte ligada a uma carga

A DUAL INPUT BIDIRECTIONAL POWER CONVERTER FOR CHARGING AND DISCHARGING A PHEV BATTERY

This thesis looks at a new design for a dual input bidirectional power converter (DIBPC) for charging and discharging a PHEV battery. The design incorporates a power factor correcting rectifier aimed at optimizing the battery charging efficiency from either a 120 VAC or 240 VAC source or discharging the battery to a usable AC voltage at 120 VAC. For simplicity and cost-effectiveness, the DIBPC is constructed using a standard IGBT 6-pack intended for motor control. The DIBPC is designed specifically to provide efficient operation with 120 VAC and 240 VAC inputs while achieving a very low THDI. The DIBPC also needs to be able to provide AC output power at 120 VAC with the flexibility to output at 240 VAC in the future. The DIBPC was tested first in simulation, and then in experimentation. The DIBPC consists of two portions, an AC/DC converter and a DC/DC converter. Although both were simulated, only the AC/DC converter was constructed. Testing under various load values and in each mode of operation provided ample data to show the DIBPC can meet all design goals. When operating as a rectifier, the DIBPC produces between 7.4% and 13.35% THDI and a DC voltage ripple of 8 VP-P or less at 400 VDC. At 120 VAC and 240 VAC an efficiency of 84.5% and 94.6% was achieved, respectively. When operating as an inverter, the DIBPC produces less than 6% THDV and 7% THDI, while outputting a voltage between 114 and 128 VRMS. Overall, the THDI in the charging mode easily meets and exceeds all standards and design constraints set forth, including IEC 61000-3-4. The efficiency with a 120 VAC input, however, is less than expected - about 84%

High Power, Medium Frequency, and Medium Voltage Transformer Design and Implementation

Many industrial applications that require high-power and high-voltage DC-DC conversion are emerging. Space-borne and off-shore wind farms, fleet fast electric vehicle charging stations, large data centers, and smart distribution systems are among the applications. Solid State Transformer (SST) is a promising concept for addressing these emerging applications. It replaces the traditional Low Frequency Transformer (LFT) while offering many advanced features such as VAR compensation, voltage regulation, fault isolation, and DC connectivity. Many technical challenges related to high voltage stress, efficiency, reliability, protection, and insulation must be addressed before the technology is ready for commercial deployment. Among the major challenges in the construction of SSTs are the strategies for connecting to Medium Voltage (MV) level. This issue has primarily been addressed by synthesizing multicellular SST concepts based on modules rated for a fraction of the total MV side voltage and connecting these modules in series at the input side. Silicon Carbide (SiC) semiconductor development enables the fabrication of power semiconductor devices with high blocking voltage capabilities while achieving superior switching and conduction performances. When compared to modular lower voltage converters, these higher voltage semiconductors enable the construction of single-cell SSTs by avoiding the series connection of several modules, resulting in simple, reliable, lighter mass, more power dense, higher efficiency, and cost effective converter structures. This dissertation proposes a solution to this major issue. The proposed work focuses on the development of a dual active bridge with high power, medium voltage, and medium frequency control. This architecture addresses the shortcomings of existing modular systems by providing a more power dense, cost-effective, and efficient solution. For the first time, this topology is investigated on a 700kW system connected to a 13kVdc input to generate 7.2kVdc at the output. The use of 10kV SiC modules and gate drivers in an active neutral point clamped to two level dual active bridge converter is investigated. A special emphasis will be placed on a comprehensive transformer design that employs a multi-physics approach that addresses all magnetic, electrical, insulation, and thermal aspects. The transformer is designed and tested to ensure the system’s viability

A High Gain AC-DC Rectifier Based on Current-Fed Cockcroft-Walton Voltage Multiplier for Motor Drive Applications

This paper proposes a novel high-gain AC-DC converter based on the Cockcroft-Walton (CW) voltage multiplier which can be utilized in motor drive systems with low input voltage. In this topology, use of the voltage multiplier and boost circuit results in the increment of converter gain which has a significant impact on the cost and efficiency of the system. Moreover, in this converter, the AC voltage is directly changed to DC voltage using the switching method in high frequency and, as well, the power factor is corrected. Besides, this high-frequency converter contributes to the reduction of output ripple. On the other hand, cost efficiency, the low voltage stress on capacitors and diodes, compactness, and the high voltage ratio, are achieved from the Cockcroft-Walton circuit. Furthermore, the hysteresis method is presented for converter switching to correct the power factor. The converter is simulated in MATLAB software to demonstrate the effectiveness of the suggested method. Lastly, a laboratory prototype of the suggested converter is built, several tests are done in order to verify the theoretical analysis, and comprehensive comparison with the state-of-the-art converter is done.© 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).fi=vertaisarvioitu|en=peerReviewed

High-Performance Isolated Bidirectional DC-DC Converter

Conversores DC-DC bidireccionais têm vindo a ganhar atenção na área da eletrónica de potência devido ao aumento da necessidade de um fluxo de potência controlado entre dois barramentos DC. Aplicações típicas podem ser facilmente listadas, indo desde unidades de produção de energia renovável até veículos elétricos e híbridos. Estes conversores podem apresentar funcionalidades como elevada densidade energética e performance, assim como isolamento galvânico entre cada porto. Desta forma, a AddVolt requisitou que tal conversor fosse incluído na sua solução de travagem regenerativa. Com esta dissertação, um conversor DC-DC bidireccional e isolado é proposto, sendo que todos os aspetos desde revisão bibliográfica, modelação, design, simulação, implementação, teste e validação são abrangidos. Um conversor Dual-Active Bridge (DAB) de média potência e alta frequência é a topologia escolhida. Após validação de quer a topologia como a malha de controlo desenhada num ambiente computacional, um protótipo experimental é assemblado e testado com sucesso. O isolamento galvânico é garantido e atingido através de um transformador de alta frequência desenhado e enrolado pelo autor.Bidirectional DC-DC converters have been gaining attention in the field of power electronics due to the increasing need of a controlled power flow between two DC buses. Typical applications can be easily listed, ranging from renewable energy production units to electric and hybrid vehicles. Such converters can feature characteristics as high power density and performance as well as isolation between each port. As a result, AddVolt has commissioned that such a converter should be included in its regenerative breaking solution. Within this dissertation, a bidirectional isolated DC-DC converter is proposed, and all aspects from literature review, modelling, design, simulation, implementation, testing and validation are deeply covered. A medium-power high frequency Dual-Active Bridge (DAB) converter is the chosen topology. After validation of both the topology and control structure in a computational environment, an experimental prototype is assembled and successfully tested. Galvanic isolation is granted and achieved by a self-designed and in-house wound high frequency transformer