Analysis of Capacitor Charging Characteristics and Low-Frequency Ripple Mitigation by Two New Voltage-Balancing Strategies for MMC-Based Solid-State Transformers

Power grids are evolving with the aim to guarantee sustainability and higher levels of power quality for universal access to electricity. More specifically, over the last two decades, power grids have been targeted for significant changes, including migration from centralized to decentralized paradigms as a corollary of intensive integration of novel electrical technologies and the availability of derived equipment. This paper addresses a review of a disruptive vision of future power grids, mainly focusing on the use of hybrid AC/DC grids and solid-state transformers technologies. Regarding hybrid AC/DC grids in particular, they are analyzed in detail in the context of unipolar and bipolar DC grids (i.e., two-wire or three-wire DC grids), as well as the different structures concerning coupled and decoupled AC configurations with low-frequency or high-frequency isolation. The contextualization of the possible configurations of solid-state transformers and the different configurations of hybrid transformers (in the perspective of offering benefits for increasing power quality in terms of currents or voltages) is also analyzed within the perspective of the smart transformers. Additionally, the paper also presents unified multi-port systems used to interface various technologies with hybrid AC/DC grids, which are also foreseen to play an important role in future power grids (e.g., the unified interface of renewable energy sources and energy storage systems), including an analysis concerning unified multi-port systems for AC or DC grids. Throughout the paper, these topics are presented and discussed in the context of future power grids. An exhaustive description of these technologies is made, covering the most relevant and recent structures and features that can be developed, as well as the challenges for the future power grids. Several scenarios are presented, encompassing the mentioned technologies, and unveiling a progressive evolution that culminates in the cooperative scope of such technologies for a disruptive vision of future power grids.

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Component Sizing and Voltage Balancing of MMC-based Solid-State Transformers Under Various AC-Link Excitation Voltage Waveforms

2019 IEEE Applied Power Electronics Conference and Exposition (APEC) ◽

10.1109/apec.2019.8721891 ◽

2019 ◽

Author(s):

Lei Zhang ◽

Jiangchao Qin ◽

Qing Duan ◽

Wanxing Sheng

Keyword(s):

Solid State ◽

Excitation Voltage ◽

Voltage Balancing ◽

Solid State Transformers ◽

Component Sizing

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Solid-State Transformers: Fundamentals, Topologies, Applications, and Future Challenges

Sustainability ◽

10.3390/su14010319 ◽

2021 ◽

Vol 14 (1) ◽

pp. 319

Author(s):

Saniya Khan ◽

Khaliqur Rahman ◽

Mohd Tariq ◽

Salman Hameed ◽

Basem Alamri ◽

...

Keyword(s):

Solid State ◽

Power Flow ◽

Control Strategies ◽

Low Frequency ◽

Origin And Evolution ◽

Solid State Transformers ◽

The Future ◽

Future Challenges ◽

Converter Topologies ◽

And Control

Solid-state transformers (SSTs) have emerged as a superior alternative to conventional transformers and are regarded as the building block of the future smart grid. They incorporate power electronics circuitry and high-frequency operation, which allows high controllability and enables bi-directional power flow, overcoming the limitations of conventional transformers. This paper presents a detailed analysis of the solid-state transformer, expounding the fundamentals, converter topologies, applications, and future challenges of the SST in a systematic manner. The paper discusses the necessity of improved replacement of the low-frequency transformers (LFTs) and presents the configuration of SST. It presents SST fundamentals in individual stages and explores its origin and evolution. The basic topologies, their specifications, and control strategies are also described. The applications of SST as a replacement of LFTs are discussed along with recent applications. The future challenges for real-time implementation of SSTs are explored, and research directions are proposed.

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Voltage Balancing Methods for Inner and Outer Switches of Three-level Resonant DC-DC Converter for Solid State Transformers

2020 IEEE 9th International Power Electronics and Motion Control Conference (IPEMC2020-ECCE Asia) ◽

10.1109/ipemc-ecceasia48364.2020.9367950 ◽

2020 ◽

Author(s):

Qintian Fu ◽

Binbin Li ◽

Xiaodong Zhao ◽

Shukai Mao ◽

Dianguo Xu ◽

...

Keyword(s):

Solid State ◽

Voltage Balancing ◽

Solid State Transformers

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Flyback Converter for Solid-State Lighting Applications with Partial Energy Processing

Electronics ◽

10.3390/electronics10010060 ◽

2020 ◽

Vol 10 (1) ◽

pp. 60

Author(s):

Mario Ponce-Silva ◽

Daniel Salazar-Pérez ◽

Oscar Miguel Rodríguez-Benítez ◽

Luis Gerardo Vela-Valdés ◽

Abraham Claudio-Sánchez ◽

...

Keyword(s):

Solid State ◽

Power Supply ◽

Design Methodology ◽

Low Frequency ◽

Solid State Lighting ◽

Voltage Source ◽

Flyback Converter ◽

Partial Energy ◽

In Series ◽

Energy Processing

The main contribution of this paper is to show a new AC/DC converter based on the rearrangement of the flyback converter. The proposed circuit only manages part of the energy and the rest is delivered directly from the source to the load. Therefore, with the new topology, the efficiency is increased, and the stress of the components is reduced. The rearrangement consist of the secondary of the flyback is placed in parallel with the load, and this arrangement is connected in series with the primary side and the rectified voltage source. The re-arranged flyback is only a reductive topology and with no magnetic isolation. It was studied as a power supply for LEDs. A low frequency averaged analysis (LFAA) was used to determine the behavior of the proposed circuit and an equivalent circuit much easier to analyze was obtained. To validate the theoretical analysis, a design methodology was developed for the re-arranged flyback converter. The designed circuit was implemented in a 10 W prototype. Experimental results showed that the converter has a THDi = 21.7% and a PF = 0.9686.

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