Skip to main content
U.S. Department of Energy
Office of Scientific and Technical Information

New Modulation and Impact of Transformer Leakage Inductance on Current-Source Solid-State Transformer

Journal Article · · IEEE Transactions on Power Electronics

This article presents a novel modulation scheme for device voltage stress mitigation and comprehensive analysis of the impact of transformer leakage inductance in a current-source solid-state transformer (SST). Different from dual active bridge (DAB) SST, the operation of the current-source SST is similar to that of a flyback converter. The device bridge on only one side of the transformer is active to store energy into or release energy from the magnetizing inductance which acts as a current-source dc link. Such flyback operation with reverse-blocking switches can lead to additional device voltage stress and incomplete zero-voltage switching (ZVS) on the current-source soft-switching solid-state transformer (S4T) under conventional modulation. A new modulation scheme is proposed to address this issue. Moreover, different from the DAB, the leakage inductance of the medium-frequency transformer (MFT) in the S4T is a parasitic element similar to that in a matrix SST and can cause additional device voltage stress. Though the resonant capacitors, originally added to achieve ZVS, can absorb and recycle the leakage energy in the S4T, these capacitors need to be increased with larger leakage inductances to limit the voltage stress. However, large resonant capacitors can result in more lost duty cycles and reduced efficiency. The impact of such leakage inductance on device voltage stress is analyzed comprehensively, which is critical to guide future research and design of the S4T. Experimental results from S4T prototypes for DC-DC, multiport AC-DC, and AC-AC conversion with 1:1 and 4:1 MFT comprehensively verify the proposed concepts. Lastly, a case study of a three-phase AC-AC S4T over a power range from 1 kVA to 100 kVA each module reveals that the MFT leakage inductance should be less than 1% of the magnetizing inductance for safe operation.

Research Organization:
Georgia Inst. of Technology, Atlanta, GA (United States)
Sponsoring Organization:
USDOE Advanced Research Projects Agency - Energy (ARPA-E)
Grant/Contract Number:
AR0000899
OSTI ID:
1892477
Journal Information:
IEEE Transactions on Power Electronics, Journal Name: IEEE Transactions on Power Electronics Journal Issue: 1 Vol. 37; ISSN 0885-8993
Publisher:
IEEECopyright Statement
Country of Publication:
United States
Language:
English

References (41)

Performance characterization of a high-power dual active bridge DC-to-DC converter journal January 1992
A three-phase soft-switched high-power-density DC/DC converter for high-power applications journal January 1991
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
New Single-Stage Soft-Switching Solid-State Transformer with Reduced Conduction Loss and Minimal Auxiliary Switch conference March 2020
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
Lightning Impulse Protection for Grid-connected Solid-state Transformers conference October 2020
Novel Modulation Strategy to Eliminate Device Overvoltage Stress and Enable True ZVS Operation in the Soft-Switching Solid-State Transformer conference October 2020
Review of Solid-State Transformer Technologies and Their Application in Power Distribution Systems journal September 2013
Topology and Control Method of a Single-Cell Matrix-Type Solid-State Transformer journal September 2020
The Smart Transformer: Impact on the Electric Grid and Technology Challenges journal June 2016
Solid-State Transformer and MV Grid Tie Applications Enabled by 15 kV SiC IGBTs and 10 kV SiC MOSFETs Based Multilevel Converters journal July 2015
Solid-State Transformer for Grid Interface of High-Power Multipulse Rectifiers journal September 2018
A Rotational Control in Medium-Voltage Modular Solid-State Transformer-Based Converter System journal November 2019
Accurate Small-Signal Model for the Digital Control of an Automotive Bidirectional Dual Active Bridge journal December 2009
Extended-Phase-Shift Control of Isolated Bidirectional DC–DC Converter for Power Distribution in Microgrid journal November 2012
Power Electronic Traction Transformer-Low Voltage Prototype journal December 2013
Isolated ZVS High-Frequency-Link AC-AC Converter With a Reduced Switch Count journal August 2014
A Single-Stage Solid-State Transformer for PWM AC Drive With Source-Based Commutation of Leakage Energy journal March 2015
Research on Unbalanced-Load Correction Capability of Two Power Electronic Transformer Topologies journal June 2015
Power and Voltage Balance Control of a Novel Three-Phase Solid-State Transformer Using Multilevel Cascaded H-Bridge Inverters for Microgrid Applications journal April 2016
Full-Process Operation, Control, and Experiments of Modular High-Frequency-Link DC Transformer Based on Dual Active Bridge for Flexible MVDC Distribution: A Practical Tutorial journal September 2017
Isolated Modular Multilevel DC–DC Converter With DC Fault Current Control Capability Based on Current-Fed Dual Active Bridge for MVDC Application journal March 2018
A Reduced Switch Count Single-Stage Three-Phase Bidirectional Rectifier With High-Frequency Isolation journal November 2018
Multirate Digital Signal Processing and Noise Suppression for Dual Active Bridge DC–DC Converters in a Power Electronic Traction Transformer journal December 2018
Design and Implementation of High Efficiency Control Scheme of Dual Active Bridge Based 10 kV/1 MW Solid State Transformer for PV Application journal May 2019
A Comprehensive Harmonic Analysis and Control Strategy for Improved Input Power Quality in a Cascaded Modular Solid State Transformer journal July 2019
A Three-Phase Modular Isolated Matrix Converter journal December 2019
Active Magnetizing Current Splitting ZVS Modulation of a 7 kV/400 V DC Transformer journal February 2020
An Isolated Modular Multilevel Converter (I-M2C) Topology Based on High-Frequency Link (HFL) Concept journal February 2020
Research on Single-Stage High-Frequency-Link SST Topology and Its Optimization Control journal August 2020
Soft-Start Procedure for a Three-Stage Smart Transformer Based on Dual-Active Bridge and Cascaded H-Bridge Converters journal October 2020
FEM-Based Statistical Data-Driven Modeling Approach for MFT Design Optimization journal October 2020
Characterization of 3.3-kV Reverse-Blocking SiC Modules for Use in Current-Source Zero-Voltage-Switching Converters journal January 2021
Analysis of Capacitor Charging Characteristics and Low-Frequency Ripple Mitigation by Two New Voltage-Balancing Strategies for MMC-Based Solid-State Transformers journal January 2021
Comparison of Analytical Models of Transformer Leakage Inductance: Accuracy Versus Computational Effort journal January 2021
DC Solid State Transformer Based on Three-Level Power Module for Interconnecting MV and LV DC Distribution Systems journal February 2021
Soft-Switching Solid-State Transformer With Reduced Conduction Loss journal May 2021
Stacked Low-Inertia Converter or Solid-State Transformer: Modeling and Model Predictive Priority-Shifting Control for Voltage Balance journal August 2021
SiC-Based 5-kV Universal Modular Soft-Switching Solid-State Transformer (M-S4T) for Medium-Voltage DC Microgrids and Distribution Grids journal October 2021
15 kV SiC MOSFET: An Enabling Technology for Medium Voltage Solid State Transformers journal June 2017