@article{sharma_iyer_bhattacharya_zou_2024, title={New Mesh Configurations With Decentralized Droop Control Method for DC Microgrids}, volume={71}, ISSN={["1557-9948"]}, url={https://doi.org/10.1109/TIE.2023.3245220}, DOI={10.1109/TIE.2023.3245220}, abstractNote={This article proposes new, practical, and scalable mesh configurations for dc microgrids. The new mesh configurations are inspired by the concepts in graph theory. A decentralized secondary droop control method without involving communication complexity is also presented in this article. The proposed control method eliminates the limitations of the conventional droop control method in the scenarios where the cable resistances in a dc microgrid system cannot be neglected. The new mesh configurations with the proposed control method achieve accurate current sharing among all the converters. The effectiveness and performance of the proposed control method are validated using circuit simulations and hardware-based experiments on existing and proposed configurations of multi-converter dc microgrid systems.}, number={1}, journal={IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS}, author={Sharma, Shrivatsal and Iyer, Vishnu Mahadeva and Bhattacharya, Subhashish and Zou, Ke}, year={2024}, month={Jan}, pages={560–571} }
 @article{sharma_iyer_bhattacharya_2023, title={A Distributed Control Method With Seamless Hot Swap Capability for Generic DC Microgrids}, volume={9}, ISSN={["1557-9948"]}, url={https://doi.org/10.1109/TIE.2023.3317835}, DOI={10.1109/TIE.2023.3317835}, abstractNote={This article proposes a distributed secondary control method for droop-controlled dc microgrid (MG) systems with ring or mesh configurations. The control method achieves accurate current sharing and improved load voltage regulation than the conventional droop method by using the bus voltage information of any bus of the dc MG system. The secondary controllers are implemented locally at each converter, thus ensuring a distributed control. The proposed method requires communication of only one signal per communication link and it needs less number of communication links than the state-of-the-art distributed secondary control methods. The method also offers a seamless hot swap capability of a converter as there is no interdependence between the secondary controllers of the converters. The effectiveness of the proposed method is validated using switching simulations and hardware-based experiments on different configurations of dc MG systems.}, journal={IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS}, author={Sharma, Shrivatsal and Iyer, Vishnu Mahadeva and Bhattacharya, Subhashish}, year={2023}, month={Sep} }
 @article{sharma_prabowo_bhattacharya_2023, title={Control of a Dual-Active-Bridge DC-DC Converter in a MV Grid-Compliant Solid-State Transformer Based DC Fast Charger}, ISSN={["1048-2334"]}, DOI={10.1109/APEC43580.2023.10131314}, abstractNote={A solid-state transformer (SST) system comprising cascaded H-bridge (CHB) and dual-active bridge (DAB) converters is a promising solution for a DC fast charger. This paper primarily focuses on the control design of the DAB converters for this system and utilizes a dual-loop based control scheme. The dual-loop consists of central voltage and inner current control loops. The inner current loops are needed to achieve current sharing between the paralleled DABs. In this paper, the inner current loop uses the DC output current of each DAB as the feedback signal. Thus, the control structure implemented in this paper is more cost-effective and computationally less intensive than the traditional approach of using a high-frequency current as the feedback signal. To provide a well-regulated output DC bus voltage, the control design considers the input disturbance due to the double-line frequency component in the DC-link voltage and the output disturbance due to load throw-off scenarios. An analytical model is derived for the complete dual-loop control structure of the DAB converter. The model evaluates the impact of disturbances due to the double-line frequency component and load throw-off scenarios on output DC bus voltage for different bandwidth combinations of the central voltage and inner current loops. Experimental results validating the analytical model are shown and discussed using a prototype of an SST system.}, journal={2023 IEEE APPLIED POWER ELECTRONICS CONFERENCE AND EXPOSITION, APEC}, author={Sharma, Shrivatsal and Prabowo, Yos and Bhattacharya, Subhashish}, year={2023}, pages={3147–3153} }
 @article{prabowo_sharma_bhattacharya_tripathi_bhavaraju_2023, title={ZVS Boundary Analysis and Design Guideline of MV Grid-Compliant Solid-State Transformer for DC Fast Charger Applications}, volume={9}, ISSN={["2332-7782"]}, url={https://doi.org/10.1109/TTE.2022.3229223}, DOI={10.1109/TTE.2022.3229223}, abstractNote={A solid-state transformer (SST) comprising a cascaded H-bridge and a dual active bridge (DAB) converter is a promising solution for a megawatt medium-voltage dc fast charger application. The new IEEE Std 1547.9-2022 comprehensively discusses extending the minimum reactive power capability to electric vehicle chargers. This article analyzes the impact of operating the grid compliant single-phase SST on the overall system. The impact of the dc-link voltage due to the single-phase implementation of the H-bridges on the DAB converter zero-voltage switching (ZVS) mode at light-load operation is highlighted. The system’s operational boundary is analyzed, which defines the reactive power capability limit while ensuring the DAB converter ZVS mode operation for the defined operating points. This ZVS mode boundary analysis is then used to develop a design guideline as part of the SST design process. The proposed guideline allows a simultaneous design of a dc-link capacitor and DAB inductance to ensure the ZVS mode for the defined operating points. It leads to dc-link capacitance reduction that offers cost- and footprint-savings. The proposed concept is validated through simulations and experimental results. Furthermore, a potential benefit analysis is provided to emphasize the effectiveness of the proposed concept. A supplementary video is included to showcase the system’s dynamic active and reactive power operation.}, number={4}, journal={IEEE TRANSACTIONS ON TRANSPORTATION ELECTRIFICATION}, author={Prabowo, Yos and Sharma, Shrivatsal and Bhattacharya, Subhashish and Tripathi, Awneesh Kumar and Bhavaraju, Vijay}, year={2023}, month={Dec}, pages={4964–4980} }
 @article{prabowo_sharma_bhattacharya_tripathi_bhavaraju_2022, title={ZVS Boundary Analysis and Design Guideline of MV Grid-Compliant Solid-State Transformer for DC Fast Charger Applications}, ISSN={["2329-3721"]}, DOI={10.1109/ECCE50734.2022.9947559}, abstractNote={A solid-state transformer comprising a cascaded H-bridge followed by a dual-active bridge converter is a promising solution for a megawatt medium voltage DC fast charger application. Previously, IEEE Std 1547– 2018 mandates a system with the capability of exporting an active power to have a minimum continuous reactive power capability to comply with IEEE Std 1547–2018. An approved revision of IEEE Std 1547–2018 comprehensively discusses to extend the minimum reactive power capability of electric vehicle chargers. This paper analyzes the impact of operating the grid compliant single-phase solid-state transformer on the overall system. The impact of the double-line frequency component of DC-link voltage on the DAB converter zero-voltage switching mode is emphasized. The zero-voltage switching mode boundary analysis is used to propose the design guidelines as part of the single-phase solid-state transformer design process. The proposed design guidelines are validated using switching simulations and experimental results.}, journal={2022 IEEE ENERGY CONVERSION CONGRESS AND EXPOSITION (ECCE)}, author={Prabowo, Yos and Sharma, Shrivatsal and Bhattacharya, Subhashish and Tripathi, Awneesh K. and Bhavaraju, Vijay}, year={2022} }
 @article{sharma_iyer_bhattacharya_2021, title={A Load Profile Based Optimized Piecewise Droop Control for DC Microgrids}, DOI={10.1109/ICDCM50975.2021.9504628}, abstractNote={Droop control is a commonly used method to parallel converters in a DC microgrid. However, the presence of non-idealities such as cable resistances can degrade the current sharing accuracy among the paralleled converters with the droop control approach. In this paper, an optimized piecewise droop-based control scheme is proposed to improve the current sharing accuracy. In the proposed method, the droop characteristics are optimized using the load current distribution. The proposed optimized piecewise droop control method is compared with both the linear and nonlinear droop based approaches over a wide range of load conditions. It is shown that the proposed piecewise droop control can achieve improved current sharing in a desired operating region based on the load distribution. The proposed control approach is verified using extensive switching circuit simulations. Further, a hardware-based experimental setup is used to validate the effectiveness of the proposed optimized piecewise droop control strategy.}, journal={2021 IEEE FOURTH INTERNATIONAL CONFERENCE ON DC MICROGRIDS (ICDCM)}, author={Sharma, Shrivatsal and Iyer, Vishnu Mahadeva and Bhattacharya, Subhashish}, year={2021} }
 @article{sharma_iyer_das_bhattacharya_2021, title={A Modified Droop Control Algorithm for DC Microgrids to Achieve Accurate Current Sharing and Improved Voltage Regulation}, ISSN={["1048-2334"]}, DOI={10.1109/APEC42165.2021.9487092}, abstractNote={Droop control is a commonly used method for load current sharing among the converters in DC microgrid applications. However, in this method, the current sharing and load voltage regulation are affected by cable resistances and other non-idealities. The conventional droop control method’s performance can be improved using secondary control algorithms that involve low-bandwidth communication channels. In this paper, an improved secondary control algorithm is proposed for a multi-source, single load bus DC microgrid system. In the proposed algorithm, the load voltage information is communicated to the individual converters, and there are no communication channels between individual converters. Thus the proposed algorithm achieves accurate current sharing and improved load voltage regulation with reduced communication channels compared to several state-of-the-art approaches. All the controllers in the proposed algorithm are implemented locally, and hence a decentralized control is achieved. The proposed algorithm’s effectiveness is validated using circuit simulations and hardware-based experiments on a two converter single load bus DC microgrid system.}, journal={2021 THIRTY-SIXTH ANNUAL IEEE APPLIED POWER ELECTRONICS CONFERENCE AND EXPOSITION (APEC 2021)}, author={Sharma, Shrivatsal and Iyer, Vishnu Mahadeva and Das, Partha Pratim and Bhattacharya, Subhashish}, year={2021}, pages={119–125} }
 @article{sharma_iyer_bhattacharya_kikuchi_zou_2021, title={Tertiary Control Method for Droop Controlled DC-DC converters in DC Microgrids}, ISSN={["2329-3721"]}, DOI={10.1109/ECCE47101.2021.9595384}, abstractNote={Droop control is a commonly used method for load current sharing between the converters in DC microgrid applications. In droop control, the current sharing performance gets degraded due to the resistance of the cables and other non-idealities. Secondary control approaches are typically used along with droop control to achieve accurate current sharing among the converters. However, secondary control methods can result in the converter steady-state output voltages exceeding the design or permissible voltage limits. In this paper, a tertiary control method is proposed to ensure that the converter steady-state output voltages remain within the safe bounds under all operating conditions. The proposed tertiary control loop gets activated when any of the converter output voltages exceed the permissible limit, and modifies the current sharing ratio to ensure that the converter steady-state output voltages are bounded. The proposed tertiary control approach is verified using extensive switching circuit simulations. Further, a hardware-based experimental DC microgrid test-bench is used to validate the effectiveness of the proposed tertiary droop control.}, journal={2021 IEEE ENERGY CONVERSION CONGRESS AND EXPOSITION (ECCE)}, author={Sharma, Shrivatsal and Iyer, Vishnu Mahadeva and Bhattacharya, Subhashish and Kikuchi, Jun and Zou, Ke}, year={2021}, pages={694–699} }