Sumida and Infineon Advance High-Voltage Isolation Technology and Solid-State Transformers
Sumida Corporation, in collaboration with Infineon Technologies AG, has successfully developed a high-isolation medium-frequency transformer (MFT) for high-density DC power architectures. The 100 kVA transformer operates at a resonant frequency of 40 kHz and achieves an insulation test voltage greater than 20 kV and a partial discharge extinction voltage (PDEV) greater than 14 kV.
The achievement addresses one of the fundamental challenges in developing next-generation SSTs that achieve high-voltage isolation while operating at higher frequencies. This enables more compact and power-dense power-conversion systems.
A New Approach to Power Conversion
Conventional AC power distribution has relied for more than a century on transformers operating at the 50/60 Hz frequency of the electrical grid. These transformers provide reliable voltage conversion and electrical isolation, but they are passive devices and are not designed to actively control power flow or directly interface with the growing number of DC-based power systems.
Solid-State Transformers take a fundamentally different approach. An SST combines high-speed power semiconductors with a medium-frequency transformer to convert and control electrical power electronically. This architecture can significantly reduce the size and weight of the magnetic transformer while enabling capabilities such as bidirectional power flow, AC/DC and DC/DC power conversion, and active control of energy moving between the grid and connected loads or energy sources.
These capabilities are becoming increasingly important as electrical infrastructure evolves to accommodate renewable energy, battery storage, EV charging, microgrids, and high-density computing. AI and data centers, for example, increasingly rely on DC power architectures, creating opportunities for SSTs to provide a more direct and controllable interface between the AC grid and high-power DC loads.
The Medium-Frequency Transformer Challenge
The medium-frequency transformer is a critical component of the SST architecture. Increasing the operating frequency from 50 or 60 Hz to tens of kilohertz allows the magnetic transformer to become substantially smaller and lighter. However, operating at higher frequency and higher voltage creates demanding new requirements for insulation, thermal management, and partial-discharge performance.
Sumida's new MFT combines 100 kVA power, 40 kHz operation, and high-voltage isolation capability, demonstrating a technology platform designed to address these challenges.
Key Technical Specifications
· Rated Power:100 kVA
· Resonant Frequency:40 kHz
· Leakage Inductance:approximately 150 μH
· Insulation Test Voltage:>20 kV
· Partial Discharge Extinction Voltage (PDEV):>14 kV
"Solid-state transformers are an important technology for the future of power conversion because they can do much more than simply change voltage or provide isolation," said Carl G. LeJambre III, Vice President of Sales, Sumida Corporation. "Our collaboration with Infineon brings together high-voltage semiconductor and magnetic technologies to address one of the key challenges in SST development—achieving high-voltage isolation at the frequencies needed for smaller, more efficient, and more flexible power-conversion systems. This achievement is an important first milestone on our journey toward 35 kV-class applications."
Sumida and Infineon: Complementary Technologies
The collaboration combines Sumida's expertise in magnetic materials, winding technologies, thermal optimization, and medium-voltage AC isolation with Infineon's expertise in high-voltage power semiconductor technology.
Infineon's 3.3 kV CoolSiC™ devices provide high-voltage switching capabilities suited to advanced SST architectures. Sumida's medium-frequency transformer provides the high-voltage isolation and magnetic power-transfer function required between the power-conversion stages.
By developing these technologies together, Sumida and Infineon are addressing two essential elements of the SST architecture as an integrated power-conversion system.
Applications for Solid-State Transformer Technology
The combination of high-frequency switching, high-voltage isolation, and electronic control of power flow opens opportunities across a growing range of applications, including:
· AI and data centers, where high-density DC power architectures are increasingly important;
· Smart grids and microgrids, where active control and bidirectional power flow can provide greater flexibility in managing energy;
· EV fast-charging infrastructure, where high-power conversion can simplify integration with the electrical grid;
· Renewable energy and battery storage, where SSTs can provide controlled interfaces between AC grids and DC generation and storage systems;
· Railway, aircraft and marine power systems, where reductions in size and weight can be particularly valuable; and
· Other high-power electrification applicationsrequiring compact, isolated high-voltage power.
The First Milestone Toward 35 kV
The successful development of the 100 kVA, 40 kHz high-isolation transformer establishes an important technology milestone as Sumida advances toward power-conversion systems with isolation requirements in the 35 kV class. "The journey toward 35 kV continues," said LeJambre.
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