Nanocrystalline Alloys Becoming a Key Driver in Solid-State Transformer Industry Upgrades

Source: China Steel News
Reporter: Zhao Ping

Recently, global technology giant NVIDIA announced that its next-generation AI data centers will widely adopt 800 V high-voltage DC technology by 2027. This groundbreaking shift is expected to redefine traditional data center power architectures and has significantly increased industry attention on one of its core components—solid-state transformers (SSTs).

On October 24, leading experts, research institutions, and major enterprises from China and abroad gathered in Shenzhen, Guangdong for the First Solid-State Transformer Industry Development and Technology Seminar (Autumn Session). The event focused on the challenges and opportunities that solid-state transformer advancement brings to the nanocrystalline alloy industry, sparking high-level discussions and cutting-edge technical exchanges.

AI-Driven Power Demands Accelerate Data Center Transformation

With the rapid surge of AI applications, demand for computing power has escalated sharply. Data center cabinet power density is rising from kilowatt to megawatt levels, and the overall power consumption of server systems is experiencing a predictable upward trend. This shift continues to drive urgent upgrades in data center power supply systems.

As a key enabler of this transformation, the full-chain efficiency of solid-state transformer systems can exceed 98.5%. Compared with traditional UPS solutions, SSTs can improve energy efficiency by more than 3 percentage points. In a 100 MW-scale data center, this translates to annual energy savings in the tens of millions of kWh, delivering both environmental and economic benefits.

Moreover, thanks to high-frequency power electronics technology, SSTs are 50%–90% smaller than traditional low-frequency transformers, significantly reducing footprint requirements and supporting high-density rack deployment. At a 1 MW power level, 800 V high-voltage DC reduces copper usage by 45% compared with 54 V low-voltage DC—saving nearly 200 kg of copper per rack and lowering both material costs and wiring complexity.

Nanocrystalline Alloys: A Breakthrough Core Material for SSTs

“Nanocrystalline alloys showcase unique advantages as the core material for solid-state transformers. Their low-loss, high-frequency characteristics are essential to pushing the efficiency limits of next-generation power equipment,” experts at the conference noted.

SST core components must operate efficiently under high-frequency conditions, requiring soft magnetic materials with low loss and high magnetic flux density. Nanocrystalline alloys, featuring atomic-level disordered structures, provide revolutionary high-frequency performance. Their electrical resistivity is three times higher than silicon steel, effectively suppressing eddy-current losses.

Published experimental results show:

• At 100 Hz, nanocrystalline alloy losses are 80% lower than silicon steel
  
• Eddy-current losses remain well controlled through optimized core thickness
  
• Cutoff frequency can extend beyond 1 MHz
  (Ferrites experience significant performance degradation above 500 kHz)
  

These attributes make nanocrystalline alloys a key enabler for SST high-frequency development.

New Breakthroughs: Tuning Magnetic Properties Through Structural Ordering

One longstanding challenge is the inherent trade-off between saturation magnetic flux density (Bs) and coercivity (Hc) in nanocrystalline alloys, which constrains device efficiency.

Encouragingly, domestic research institutions have now overcome limitations in traditional alloy compositions that were once considered untunable. A new paradigm based on structural ordering has emerged.

According to experts, the Songshan Lake Materials Laboratory has applied multi-field coupling—including rotational magnetic fields, mechanical stress fields, and temperature fields—to introduce ordered phases such as crystal-like order, Fe₄N, and α-Fe(Co) into amorphous-based soft magnetic materials. By establishing multi-scale ordering strategies— including interfacial ordering and nanocrystal–amorphous dual-phase structures—researchers have significantly improved saturation flux density, coercivity, permeability, and high-frequency losses. This work also overturns the traditional inverse relationship between magnetic strength and plasticity.

Future research aims to further expand multi-field coupling to achieve the on-demand design of next-generation amorphous materials with exceptional mechanical, magnetic, and chemical properties.

Challenges in Practical Applications: Consistency and Noise Issues Persist

Experts also highlighted real-world challenges during nanocrystalline core application testing. Two cores from the same batch and specification were wound with identical coils and subjected to high-frequency current. Thermal imaging showed significant temperature differences, even within the same batch. Cut gaps exhibited noticeably higher temperatures due to magnetic-field concentration and increased eddy-current losses, becoming the hottest spots in the core and affecting thermal stability and reliability. Other areas of the magnetic circuit also displayed uneven loss distribution.

Manufacturers urgently need to address consistency issues in nanocrystalline magnetic cores.

Additionally, as a rapidly quenched metallic glass, nanocrystalline alloys possess some inherent limitations:

• Not suitable for low-permeability cores used in resonant circuits
  
• Higher noise levels below 16 kHz
  
• High sensitivity to mechanical stress
  

These challenges provide new directions for future research and material optimization.

Conclusion: A New Era for Nanocrystalline Alloy Innovation

The seeds of a nanocrystalline alloy materials revolution have clearly begun to sprout. The deep integration of nanocrystalline alloys and solid-state transformers is not only driving a leap forward in power equipment efficiency but also reshaping the foundation of the future energy internet.

As a new generation of high-frequency, low-loss soft magnetic materials, nanocrystalline alloys are poised to accelerate the upgrading of the solid-state transformer industry.