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An Artificial Intelligence Approach for Real-Time Tuning of Weighting Factors in FCS-MPC for Power Converters

Authors: Sergio Vazquez; Daniel L. Marino; Eduardo Zafra; Maria Dolores Valdes Pena; Juan J. Rodriguez-Andina; Leopoldo Garcia Franquelo; Milos Manic Extended Abstract: In this paper a finite control set model predictive control is used to track a current reference in a power converter connected to an RL load. An artificial intelligence (AI) approach is presented for real-time determination of the weighting factor that regulates the average switching frequency, independently of the operating point. The paper focuses on the design, training, and digital implementation of an artificial neural network (ANN) that can be developed in a low-cost control platform. It is presented a sampling and offline ANN training procedure, together with a low-cost hardware implementation based on integer quantization of the ANN. The above approach provides a standalone application, serving as a framework for development of ANN applications for power-converters. The main advantage of the presented approach is that the ANN inference is executed in real-time. In this way, the weighting factor is automatically updated in real-time, allowing the system to quickly adapt to any reference step changes, and consequently provide the desired behavior. Executing the setup in laboratory prototype confirmed the theoretical analysis and successful tracking of the reference frequency. Published in IEEE Transactions on Industrial ...
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A Resonant Frequency Tracking Technique For LLC Converters Based DC Transformers

Authors: Yuqi Wei, Quanming Luo, Alan Mantooth Extended Abstract: Large circulating current and reactive power exist for the LLC / CLLC converter in the case that f s < f r , where f s is the switching frequency and f r is the resonant frequency; on the other hand, in the scenario of f s > f r , the switching losses for both primary and secondary semiconductor devices are increased due to the large turn-off current and high di / dt related reverse recovery issue, respectively. When operating at the natural resonant frequency of inductor and capacitor or f s = f r , the regulation capability for LLC / CLLC converter is lost since the voltage conversion ratio is constant. This application of the LLC is known as a DC transformer (DCX), which has been widely adopted in energy storage systems as an interconnection between different units. However, due to the variation of circuit parameters, the switching frequency is different from the resonant frequency, which results in converter efficiency degradation and loss of output voltage regulation capability for two-stage applications. In this article, by sensing both the output and input voltage, the converter voltage conversion ratio is computed on-line. Based on the comparison result between the calculated gain and unity, the switching ...
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Towards Grid of Microgrids: Seamless Transition between Grid-Connected and Islanded Modes of Operation

Authors: Silvanus D'silva, Mohammad Shadmand, Sertac Bayhan, Haitham Abu-Rub Extended Abstract: With the ever-increasing number of blackouts in distribution systems arising from a variety of natural and manmade disasters, the frequent and necessary isolation/reconnection of loads without power deviations/fluctuations has become an important issue. Grid of microgrids (MGs) is a promising solution towards a highly resilient and efficient power grid operation. To facilitate this implementation, seamless transition with the utility grid is a key feature today’s MG control scheme need to possess. This transition is of great prominence, especially after the accelerated adaptation of distributed renewable energy sources (RES) in MGs. This ability of the MGs should ensure uninterrupted energy services to critical loads and infrastructures. Thus, the implementation of MG control strategies to enable smooth transition between grid-connected (GC) and islanded (IS) operation modes is mandatory. The control scheme implemented should therefore be capable of mitigating the stirring voltage/current deviations due to frequency/phase misalignment during the transition process. This paper provides an overview of the various MG control schemes that enable seamless transition between GC and IS modes of operation. The main purpose of this paper is to provide a generic overview of the challenges and existing techniques available in literature ...
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A Survey on Event-Triggered Sliding Mode Control

Authors: Abhisek K. Behera; Bijnan Bandyopadhyay; Michele Cucuzzella; Antonella Ferrara and Xinghuo Yu Extended Abstract: Event-triggered control (ETC) is a novel strategy for designing controllers for sampled-data systems. Here, by incorporating an event condition in the feedback loop, the data transmission is regulated over the network subject to the satisfactory response of the closed-loop system. Under this feedback constraint, the ETCs have shown promising results, even in the presence of uncertainties/disturbances. Sliding mode control (SMC) is an effective tool for uncertain systems guaranteeing robust performance. In the past decade, many results were reported on the design of event-triggered SMC, which can handle both feedback constraint and disturbance effect. Indeed, a new sliding motion is obtained, known as the practical sliding mode, in which any arbitrary bound for the sliding function can be achieved by appropriately designing the event condition. This paper catalogues almost all developments in event-triggered SMC, from its initial proposal to various applications till the appearance of this paper. We give an overview of the design of classical SMC for both linear and nonlinear systems in the event-triggering framework. The different event-triggering conditions are covered with emphasis on their respective advantages. Some discussion is also presented on the higher-order SMC. The wide application of ...
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ZPUC

ZPUC: A New Configuration of Single DC Source for Modular Multilevel Converter Applications

Saeed Arazm, Kamal Al-Haddad ABSTRACT: Z packed U-cell (ZPUC) converter topology is presented in this paper as a new type of multilevel converter topology that can be operated in a single phase as well as in three-phase configurations while using a single DC source. Since each U-cell includes two switches which operates complimentarily and one capacitor, in this topology, three U-cells are needed to generate 5 or 7 voltage levels. Moreover, the proposed configuration for the ZPUC is more appropriate for high-power application modular multilevel converters (MMCs) to increase the voltage levels compared to other topologies. ZPUC generates unipolar waveform which is highly functional on MMC application to generate higher voltage levels compared to bipolar topologies such as (packed U-cells) PUC and full-bridge (FB). However, it requires DC fault circuit breaker for disconnecting of DC fault current. Moreover, the components count of ZPUC are less than half of the half-bridge (HB) unipolar topology. The remarkable note is that the DC voltage source on ZPUC is divided among the submodules of leg (one phase), while it is divided among the submodules of the arm on the other topologies. This solution reduces the cost, weight, and volume of the ZPUC converter compared ...
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DCM-Based Bridgeless PFC Converter for EV Charging Application

Authors: Abhinandan Dixit; Karan Pande; Sivanagaraju Gangavarapu; Akshay Kumar Rathore Abstract:  On-board battery chargers (OBC) are a crucial part of electric vehicle (EV) industry. OBC comprises of a two-stage structure where front-end converter is a power factor correction (PFC) unit and a back-end DC-DC converter which controls the battery charging process. The front-end converter is the most complex part of the battery charger in terms of control and design. This paper proposes a single-phase switched-mode bridgeless ac-dc buck-boost derived converter that can serve as a front-end converter for the on-board EV charging application. The bridgeless scheme rules out the orthodox bridge rectifier and the affiliated losses. The proposed converter operates in discontinuous current conduction mode (DCM), thus achieving natural power factor correction for variable ac input. In addition to this, sensing of input voltage and input current is fended off because of DCM operation making the converter reliable, cost-effective, and robust compared with conventional continuous current conduction mode converters. Furthermore, the control becomes simple with the employment of a single sensor and the elimination of the phase-locked loop. The proposed front-end converter is well suited for low-voltage battery chargers ranging between 1.0 and 3.3 kW installed in golf-carts and E-rickshaws. A ...
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Isolation barrier design

Gate Drivers for Medium-Voltage SiC Devices

Authors: Anup Anurag, Sayan Acharya, Nithin Kolli and Subhashish Bhattacharya Extended Abstract: Extensive research in wide-bandgap material technology such as silicon carbide (SiC) has led to the development of medium voltage (MV) power semiconductor devices with blocking voltages of 3.3 kV to 15 kV. When these devices are used in various applications, they are exposed to a high peak voltage stress and a very high dv/dt (50 V/ns to 100 V/ns). These impose stringent requirements on the gate driver requiring a high isolation voltage capability along with a high dv/dt ruggedness, which makes it necessary to have an ultra-low coupling capacitance between primary and secondary sides of the isolated gate driver power supply. One of the key issues in achieving this MV isolation pertains to the necessary clearance and creepage requirements, as defined in IEC 61800-5-1 standards. For the successful operation of these gate drivers to be demonstrated in MV converter applications such as Solid-State Transformers [SST], MV grid-connected converters, and MV motor drives, substantial research to improve the gate drivers' performance and provide a plug-and-play solution is needed. This work aims to comprehensively review and develop these gate drivers and consolidate various required design features concerning their galvanic isolation ...
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A Comprehensive Review of the Integration of Battery Energy Storage Systems Into Distribution Networks

Authors: Marco Stecca; Laura Ramirez Elizondo; Thiago Batista Soeiro; Pavol Bauer; Peter Palensky Abstract: Recent developments in the electricity sector encourage a high penetration of Renewable Energy Sources (RES). In addition, European policies are pushing for mass deployment of Electric Vehicles (EVs). Due to their non-controllable characteristics, these loads have brought new challenges in distribution networks, resulting in increased difficulty for Distribution System Operators (DSOs) to guarantee a safe and reliable operation of the grid.  Battery Energy Storage Systems (BESSs) are promising solutions for mitigating the impact of the new loads and RES. In this paper, different aspects of the BESS's integration in distribution grids are reviewed. At first, the physical layer will be considered, focusing on the main battery technologies commercially available and on the power electronics converter. Secondly, the different functionalities that a grid-connected BESS can provide will be investigated, and then its sizing, location and control in distribution network will be discussed. In addition, an overview of actual BESSs installations is given. All in all, this paper aims at providing a comprehensive view of BESSs integration in distribution grids, highlighting the main focus, challenges, and research gaps for each one of these aspects. Published in IEEE ...
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voltage gain graph

A Simple Technique for Fundamental Harmonic Approximation Analysis in Parallel and Series-Parallel Resonant Converters

Authors: Akshay Kumar Rathore, Senior member IEEE, and Venkata R Vakacharla, student member IEEE Abstract The Fundamental Harmonic Approximation (FHA) analysis favored engineers by alleviating obstacles in analysis, loss computation, and optimization by reducing complex resonant converter into a mere Resistance-Inductance-Capacitance (RLC) circuit. However, to improve the power density of an X-ray machine power supply, elimination of filter inductor leaves parallel and series-parallel resonant converters with capacitive filter in output, which forces the Rear End Rectifier (RER) to draw discontinuous currents. These unprecedented discontinuous currents through resonant tanks complicate the FHA analysis, a simple and elegant approach, by forcing it to adopt computer-aided techniques and numerical methods similar to the time domain, state-space, and state-plane approaches. Therefore, all available tools, including traditional FHA, fail to model these converters with reduced complexity and labor. Addressing this issue, this paper presents a technique to restore the simplicity of FHA analysis in the case of parallel and series-parallel resonant converters terminated with capacitive filters. The authenticity, simplicity, and accuracy of the proposed technique are demonstrated through results. Further, a detailed comparison with existing modeling techniques is also provided. This paper is published in IEEE Transactions on Industrial Electronics Check full paper at: ...
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Small-Signal Modeling and Closed-Loop Control of a Parallel–Series/Series Resonant Converter for Wireless Inductive Power Transfer

Authors: Suvendu Samanta ; Akshay Kumar Rathore Abstract: Usually, the parallel-compensated inductive power transfer (IPT) topology fed by a current-source inverter is controlled through variable switching frequency and fixed 50% duty cycle method. This enables the system to operate at resonance frequency, which drifts due to load and other parameter variations. Owing to this control constraint, the load requirements are fulfilled by adding extra dc-dc chopper at the output. This paper presents a new control technique for a parallel-series/series IPT network, fed from a full-bridge current-source inverter to meet the load demand directly by an inverter. Therefore, the extra chopper stage at the output side of the converter is eliminated. The control goals are achieved through a two-loop control method, where the inner input current loop controls the source current and the outer output current loop meets the load requirements. The detailed steady-state operation, converter design, small-signal modeling, and control are reported, and experimental results obtained from a 1.6-kW lab prototype are included to verify the mathematical analysis. This paper is published in IEEE Transactions on Industrial Electronics Check full paper at: https://ieeexplore.ieee.org/document/8331928 ...
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