A. Shekhar
76 records found
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High-power flexible dc links employ modular multilevel converters (MMC) for compact active power redirection in medium and high voltage grids. During contingencies, such converters may need to provide an enhanced active power capacity to avoid overload in vulnerable grid location
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Targeting a climate-neutral maritime sector drives the adoption of the all-electric ship (AES). While AESs can utilize both ac and dc shipboard power systems (SPS), a dc system offers advantages in efficiency, power density, and source synchronization. However, the enhanced netwo
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To tackle the potential grid overloading issue induced by excessive Electric Vehicles (EV) charging demand, a Low Voltage (LV) grid congestion management algorithm with three centralised EV charging management schemes is proposed in this study. The developed algorithm integrates
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Modular Multilevel Converters (MMCs) offer significant advantages in the medium to high-voltage settings. The modular architecture of MMCs allows for redundant submodules (SMs) to improve overall reliability. These redundant SMs can be deployed using various redundancy strategies
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The role of power electronics in advancing electrification and sustainability is pivotal. The Modular Multilevel Converter (MMC) is a leading candidate for connecting offshore wind farms to the power grid. However, one of the primary concerns with MMC is its reliability, primaril
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Modular multilevel converters are favorable for efficiently operating high-power usages. The required number of components significantly increases when higher modularity is introduced for the given voltage level, thus reducing the system's reliability. This article suggests a mix
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Identifying faulty lines and their accurate location is key for rapidly restoring distribution systems. This will become a greater challenge as the penetration of power electronics increases, and contingencies are seen across larger areas. This paper proposes a single terminal me
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Reliability Assessment of Modular Multilevel Converters
A Comparative Study of MIL and Mission Profile Methods
Power electronics converters are essential for power generation, transmission, and distribution. The modular multilevel converter (MMC) is highly valued for its versatility, high efficiency, and robust control capabilities. Since MMC is composed of many components, its reliabilit
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Due to the deficient passivation of the interface between silicon carbide and silicon dioxide, the defect-induced capture and release of trapped charges triggered by external Bias Temperature Stress (BTS) leads to parameter shifts and degraded device performance. This study model
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The rising demand for electric vehicles (EVs) in the face of limited grid capacity encourages the development and implementation of smart charging (SC) algorithms. Experimental validation plays a pivotal role in advancing this field. This article formulates a hierarchical mixed i
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This article discusses the various ways in which the stresses experienced by the IGBTs and diodes in a Dual Active Bridge (DAB) are asymmetric. This asymmetry can be between the two bridges or between IGBTs and diodes on both bridges. The terminal voltage, transformer ratio and t
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In DC shipboard power systems (DC-SPS), the enhanced network complexity and high penetration of power electronic devices make the system level reliability a critical design aspect. This paper proposes a stochastic framework for the reliability assessment of DC-SPSs based on a thr
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In the realm of electric mobility, fast chargers for electric vehicles (EVs) play a critical role in mitigating range anxiety while driving. The converter in these chargers usually has a load profile consisting of a high-current pulse to swiftly recharge the EV battery, followed
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In this article, we provide a comprehensive review of defect formation at the atomic level in interfaces and gate oxides, focusing on two primary defect types: interface traps and oxide traps. We summarize the current theoretical models and experimental observations related to th
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Low-Voltage dc System Building Blocks
Integrated Power Flow Control and Short Circuit Protection
Low-voltage direct current (LVdc) systems are a promising technology for systems with a high penetration of renewable sources and storage that operate with bidirectional power flow. In this article, a fundamental building block for LVdc is presented for different applications, su
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EV Fast chargers are crucial to alleviate the driving range anxiety for E-mobility applications. A typical converter load profile consists of a short high-current pulse to rapidly refill the EV battery followed by a cooling-off period once the charging is completed. Power electro
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The reliability of semiconductor power devices can be studied by performing a thermal and power cycling test. In order to create the desired temperature cycles, there are four free variables to select during the power cycling test, namely the heating current, heating time, coolin
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The load profile of the power converter in EV Fast charging applications involves a short high-current pulse for rapid charging of the EV battery leading to thermal cycles on the power electronic devices. These thermal cycles can cause thermo-mechanical fatigues, which consume th
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The small, light-weight and modular Lunar rover must survive several earth days in harsh environment after its moon landing. Its power electronic system with integrated solar generation needs power for its mission and also to stay warm in very cold temperatures of the moon. This
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When operating a modular multilevel converter (MMC), a margin appears between the arm voltage and sum capacitor voltage corresponding to the power dependent ripple. This margin can be used to enhance the DC link voltage and increase the transfer capacity of an MMC-based distribut
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