Solid-State Transformer Technologies and Applications

Solid-state transformers (SSTs) represent a paradigm shift in electrical power conversion, integrating high-frequency power electronics, control circuitry and galvanic isolation to replace or augment conventional magnetic transformers. By combining AC/DC conversion stages with medium-frequency isolation transformers and DC/AC inversion, SSTs offer compactness, modularity and dynamic controllability of voltage, frequency and power flow. They facilitate seamless integration of renewable energy sources, electric vehicle charging, smart-grid architectures and microgrids, enabling bidirectional power transfer between AC and DC networks. Key applications span distribution substations, data centres, rail traction systems, offshore wind farms and aerospace power supplies. Advanced wide-bandgap semiconductors enhance switching speeds and efficiency, while modular multi-port topologies allow flexible power routing, fault tolerance and scalable ratings. The technology underpins efforts to decarbonise grids, improve power quality and increase system resilience by supporting active power management, reactive compensation and islanding capability. Ongoing challenges include thermal management, electromagnetic compatibility, protection coordination and economic viability, but recent advances in materials, packaging and control algorithms are closing the gap to commercial deployment.

Research from Nature Portfolio

No recent Nature Portfolio content available.

Research from all publishers

Recent surveys have mapped the landscape of SST design by comparing alternative two- and three-stage topologies, assessing their trade-offs in efficiency, power density and complexity. One comprehensive review evaluated single-stage and cascaded dual-active-bridge configurations, highlighting control strategies for voltage balancing, fault ride-through and reactive power support. It identified emerging trends in multi-level converters and hybrid silicon/silicon-carbide devices to push switching frequencies beyond 50 kHz while containing losses.

Another study proposed a unified classification of SST architectures, introducing standard terminology to distinguish between modular multilevel converters, resonant-link designs and dual-active-bridge-based solutions. It examined material selection for medium-frequency transformers, including nanocrystalline and ferrite cores, and outlined design criteria for insulation, winding losses and thermal performance. Control schemes for power-flow regulation, unbalance compensation and grid-support functions were synthesised to reveal gaps in dynamic modelling and real-time implementation.

Practical demonstrations have underpinned the transition to pilot deployments, with a critical review of prototype and demonstrator projects across smart grids, data centres and rail applications. This analysis documented rated values, switching frequencies and efficiency metrics, emphasising the role of inter-institutional consortia and industrial stakeholders in advancing SST proof-of-concepts. Future trends include integration with vehicle-to-grid interfaces, modular DC distribution blocks and standardised communication protocols for grid-interactive power electronics.

Solid-State Transformer Technologies and Applications publication trend

The graph below shows the total number of articles in solid-state transformer technologies and applications across all publications each year (not limited to Nature Index journals).

Technical terms

Solid-state transformer (SST): A power conversion system combining high-frequency switching, medium-frequency isolation and control electronics to replace traditional magnetic transformers and enable active power management.

Galvanic isolation: Electrical separation between input and output circuits provided by a transformer or optocoupler to prevent direct current paths and enhance safety.

Dual active bridge (DAB) converter: A bidirectional DC-DC converter topology employing two full-bridge converters linked by a high-frequency transformer to regulate power flow.

Wide-bandgap semiconductors: Materials such as silicon carbide and gallium nitride that allow higher switching frequencies, efficiencies and thermal tolerance in power electronics.

Bidirectional power flow: The capability of a converter or transformer to transfer energy in both directions, enabling regeneration, storage integration and grid support.

References

1. State of the Art of Solid-State Transformers: Advanced Topologies, Implementation Issues, Recent Progress and Improvements. IEEE Access (2020).
2. Solid State Transformers: Concepts, Classification, and Control. Energies (2020).
3. Solid State Transformers Topologies, Controllers, and Applications: State-of-the-Art Literature Review. Electronics (2018).
4. Solid State Transformers: A Critical Review of Projects with Relevant Prototypes and Demonstrators. Electronics (2023).
5. Performance Comparison of Ferrite and Nanocrystalline Cores for Medium-Frequency Transformer of Dual Active Bridge DC-DC Converter. Energies (2021).