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Title: SiC-Based 5-kV Universal Modular Soft-Switching Solid-State Transformer (M-S4T) for Medium-Voltage DC Microgrids and Distribution Grids

Journal Article · · IEEE Transactions on Power Electronics

Medium-voltage DC (MVDC) grids are attractive for electric aircraft and ship power systems, battery energy storage system (BESS), fast charging electric vehicle (EV), etc. Such EV or BESS applications need isolated bidirectional MVDC to LVDC or LVAC converters. However, the existing Si-based solutions cannot fulfill the requirements of a high-efficiency and robust converter for MVDC grids. This paper presents a 5 kV SiC-based universal modular solid-state transformer (SST). This universal current-source SST can interface either a LVAC or LVDC grid with a MVDC grid in single-stage power conversion, while the conventional dual active bridge (DAB) converter needs an additional inverter. The proposed SST module using 3.3 kV SiC MOSFETs and diodes is bidirectional and can serve as a building block in series or parallel for higher-voltage higher-power systems. The topology of each module is based on the soft-switching solid-state transformer (S4T) with reduced conduction loss, which features reduced EMI through controlled dv/dt, and high efficiency with full-range ZVS for main devices and ZCS for auxiliary devices. Operation principle of the modular S4T (M-S4T), capacitor voltage balancing control between the cascaded modules, design of components including a medium-voltage (MV) medium-frequency transformer (MFT) to realize a 50 kVA 5 kV DC to 600 V DC or 480 V AC M-S4T are presented. Importantly, the MV MFT prototype achieves very low leakage inductance (0.13%) and 15 kV insulation with coaxial cables and nanocrystalline cores. Here, the proposed universal modular SST is compared against the DAB solution and verified with DC-DC and DC-AC simulation and 4 kV experimental results. Significantly, the MV experimental results of a modular DC transformer with each module at MVDC are rarely covered in the literature and reported for the first time.

Research Organization:
Georgia Institute of Technology, Atlanta, GA (United States)
Sponsoring Organization:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
Grant/Contract Number:
EE0006521
OSTI ID:
1894263
Journal Information:
IEEE Transactions on Power Electronics, Vol. 36, Issue 10; ISSN 0885-8993
Publisher:
IEEECopyright Statement
Country of Publication:
United States
Language:
English

References (53)

Single-stage soft-switching solid-state transformer for bidirectional motor drives conference October 2017
Impact of Transformer Leakage Inductance on the Soft-Switching Solid-State Transformer conference September 2018
A Medium-Voltage Medium-Frequency Isolated DC–DC Converter Based on 15-kV SiC MOSFETs journal March 2017
Design and Experimental Testing of a Resonant DC–DC Converter for Solid-State Transformers journal October 2017
Power Electronic Traction Transformer—Medium Voltage Prototype journal July 2014
Modular Universal Converter for MVDC Applications conference September 2018
Design of a 10-kV·A Soft-Switching Solid-State Transformer (S4T) journal July 2018
Soft-Switching Solid-State Transformer With Reduced Conduction Loss journal May 2021
Resonant Power Conversion: Insights From a Lifetime of Experience journal December 2021
A Modular SiC High-Frequency Solid-State Transformer for Medium-Voltage Applications: Design, Implementation, and Testing journal June 2019
High Frequency Resonant Converters: An Overview on the Magnetic Design and Control Methods journal February 2021
Reduction of power converter EMI emission using soft-switching technique journal January 1998
Soft-Switching Power Electronics Technology for Electric Vehicles: A Technology Review journal July 2020
Protection Strategies for Medium-Voltage Direct-Current Microgrid at a Remote Area Mine Site journal July 2015
Advanced LVDC Electrical Power Architectures and Microgrids: A step toward a new generation of power distribution networks. journal March 2014
Dual-active bridge dc-dc converter systems for medium-voltage DC distribution grids conference November 2015
An ISOP Hybrid DC Transformer Combining Multiple SRCs and DAB Converters to Interconnect MVDC and LVDC Distribution Networks journal November 2020
A Multiple Modular Isolated DC/DC Converter With Bidirectional Fault Handling and Efficient Energy Conversion for DC Distribution Network journal November 2020
Control and Experiment of a TLC-MMC Hybrid DC–DC Converter for the Interconnection of MVDC and HVDC Grids journal March 2020
Multiple-Modular High-Frequency DC Transformer With Parallel Clamping Switched Capacitor for Flexible MVDC and HVDC System Applications journal December 2020
Trapezoidal Current Modulation for Bidirectional High-Step-Ratio Modular DC–DC Converters journal April 2020
Modular Hybrid-Full-Bridge DC Transformer With Full-Process Matching Switching Strategy for MVdc Power Distribution Application journal May 2020
A Method for Optimally Designing Snubber Circuits for Buck Converter Circuits to Damp LC Resonance journal August 2019
A Systematic Topology Evaluation Methodology for High-Density Three-Phase PWM AC-AC Converters journal November 2008
Current-Source Converter and Cycloconverter Topologies for Industrial Medium-Voltage Drives journal July 2008
The Past, Present, and Future of Power Electronics Integration Technology in Motor Drives journal September 2017
Effects of eddy currents in transformer windings journal January 1966
Simplified design method for litz wire conference March 2014
Characterization of 6.5 kV IGBTs for High-Power Medium-Frequency Soft-Switched Applications journal February 2014
Soft-Switching Solid-State Transformer (S4T) journal April 2018
99% Efficient 10 kV SiC-Based 7 kV/400 V DC Transformer for Future Data Centers journal June 2019
7.2 kV Three-Port Single-Phase Single-Stage Modular Soft-Switching Solid-State Transformer with Active Power Decoupling and Reduced DC-Link conference March 2020
Power Semiconductor Devices for Smart Grid and Renewable Energy Systems journal November 2017
Silicon Carbide Power Transistors: A New Era in Power Electronics Is Initiated journal June 2012
Efficiency Impact of Silicon Carbide Power Electronics for Modern Wind Turbine Full Scale Frequency Converter journal January 2011
Design Considerations and Development of an Innovative Gate Driver for Medium-Voltage Power Devices With High $dv/dt$ journal June 2019
Design Considerations of a 15-kV SiC IGBT-Based Medium-Voltage High-Frequency Isolated DC–DC Converter journal July 2015
A three-phase soft-switched high-power-density DC/DC converter for high-power applications journal January 1991
Performance characterization of a high-power dual active bridge DC-to-DC converter journal January 1992
Low-Voltage Bipolar-Type DC Microgrid for Super High Quality Distribution journal December 2010
Development and demonstration of a medium-voltage high-power DC-DC converter for DC distribution systems conference June 2014
Port Controlled Hamiltonian Modeling and IDA-PBC Control of Dual Active Bridge Converters for DC Microgrids journal November 2019
A High Power Medium Voltage Resonant Dual Active Bridge for MVDC Ship Power Networks journal March 2017
Medium-voltage DC distribution grids in urban areas conference June 2016
Parameter Design of a Three-Level Converter Based on Series-Connected HV-IGBTs journal November 2014
Comparison of the Modular Multilevel DC Converter and the Dual-Active Bridge Converter for Power Conversion in HVDC and MVDC Grids journal January 2015
Analytical Technique for Designing an RC Snubber Circuit for Ringing Suppression in a Phase-Leg Configuration journal June 2018
Adapted Auxiliary-Resonant Commutated Pole in the Dual-Active Bridge journal December 2019
Optimum Snubbers for Power Semiconductors journal September 1972
Single-Stage Control System of I-MMC-Based Island MVDC Link Receiver With Multiple Modulation Freedoms journal January 2020
The Smart Transformer: Impact on the Electric Grid and Technology Challenges journal June 2016
Characterization of 3.3-kV Reverse-Blocking SiC Modules for Use in Current-Source Zero-Voltage-Switching Converters journal January 2021
Stacked Low-Inertia Converter or Solid-State Transformer: Modeling and Model Predictive Priority-Shifting Control for Voltage Balance journal August 2021