In the process of applying nanocrystalline materials to power inverters, several issues—such as noise problems, brittleness, and consistency issues—have emerged, which to some extent have hindered their wider adoption and drawn attention. Now, these issues have been gradually resolved.

(1) Noise Issues
Noise is caused by a variety of factors:
1. The reason lies in the magnetostriction coefficient of the material itself. Ferrite materials have a relatively high magnetostriction coefficient. Although ferrite cores are solid, they can still generate noise under certain operating conditions. The magnetostriction coefficient varies depending on the composition of nanocrystalline materials. In previous years, the commonly used composition was a general-purpose alloy, which led to particularly prominent noise issues in transformers. As applications and development have deepened, different alloy compositions have been tailored for specific uses to meet the unique magnetic requirements of various devices. For instance, specialized compositions have been developed for power output transformers, current transformers, common-mode inductors, and other such components. By adjusting the alloy composition according to the requirements of power transformers, the magnetostriction coefficient has been reduced. User feedback has confirmed that the noise issue has significantly improved.
2. The cause of loose winding in the iron core is closely related to the quality of the strip material used. Deviations in strip dimensions and uneven thickness can lead to loose winding of the iron core, making it prone to noise generation. After adjusting the composition, the molten steel exhibits good fluidity, which helps improve the forming quality of the strip and, to a certain extent, provides a favorable guarantee for reducing iron-core noise.
3. Regarding issues with the inverter circuit of power inverters, a large DC component in the circuit leads to an increased working magnetic flux density in the core, which in turn causes noise. Our experiments have demonstrated that the noise level increases as the working magnetic flux density rises. Some manufacturers have adopted DC-blocking measures in their circuits, and by using nanocrystalline cores for many years, they have not encountered any noise problems.
Thanks to the improvements mentioned above, the noise issue has been basically resolved.

(2) Brittleness Issues
The brittleness of nanocrystalline iron cores primarily manifests itself in the chipping and flaking of core material, which has become a major concern reported by users. This not only poses significant challenges during installation and handling but also creates a potential risk of short circuits in the circuitry. After years of practical experience and research, the issue of brittleness has been greatly alleviated through adjustments to both composition and manufacturing processes. Following compositional adjustments, the flexibility of the strip material has improved. Additionally, reducing the thickness of the strip material has further decreased brittleness. Moreover, in the core manufacturing process, immersing the core in a stress-free adhesive ensures that the core is less likely to break, thereby effectively addressing the brittleness-related problem of core material flaking. At the same time, since the stress-free adhesive fixes the interlayer gaps within the core strip material, it prevents resonance from easily occurring, thus reducing noise generation.

(3) Consistency Issues
Consistency is related to production scale and the capacity of production equipment. From the perspective of strip quality, compared to a 50-kg-capacity device, a 500-kg-capacity device—when both produce 500 kg of strip—will clearly yield products with superior consistency in terms of composition and magnetic properties. The same holds true for heat treatment during the production process. Therefore, larger production scales and higher-capacity production equipment are conducive to better consistency.
In terms of user application, the consistency of nanocrystalline materials is mainly reflected in significant variations in saturation voltage and inductance—sometimes differing by more than a factor of two. The primary reasons for this are the poor effectiveness of magnetic field heat treatment and the lack of categorized screening during production inspection. With adjustments made to the composition used in power transformers, not only has brittleness been improved, but also the residual magnetic induction of the material has been reduced. Consequently, the effectiveness of magnetic field heat treatment has led to an increase in the core’s saturation voltage, playing a crucial role in enhancing product consistency.
There has been a gradual process of gaining a better understanding of the magnetic performance requirements for power inverter supplies. In previous years, due to relatively small volumes of use, only meeting the specified loss requirements was considered sufficient. Consequently, performance testing focused solely on measuring loss as the primary parameter. For specific users, the inspection criteria were later expanded to include measurement of induced voltage levels. As the scale of application has grown steadily, increasingly diverse requirements have emerged—among which the demand for consistent performance has become particularly prominent. Because there has been a learning curve regarding these requirements, progress has lagged somewhat in areas such as compositional improvements, production organization, and testing standards. As a result, this has had some impact on the wider adoption and application of these products. Today, however, this issue has received adequate attention, and a variety of effective measures have been implemented, leading to a significant improvement in performance consistency.

(4) Price Issues
Price is a key concern for users, especially those who are about to start using or have just begun using these products. The price is directly related to production volume. In recent years, as the applications of nanocrystalline iron cores have expanded rapidly—no longer limited to power inverter welders but also widely adopted in electroplating equipment, induction heating devices, charging systems, communication power supplies, UPS systems, X-ray machine power supplies, laser power supplies, variable-frequency drive power supplies, and other fields—production volumes have steadily increased, leading to significant price reductions. Currently, prices have fallen by approximately 40% compared to their initial levels. As application volumes continue to grow, prices will keep dropping further, and the price of nanocrystalline materials will gradually approach that of ferrites.
Currently, for power supplies with outputs exceeding 15 kilowatts, the price of nanocrystalline cores has actually fallen below that of ferrite cores. This is because ferrite cores have size limitations, making it difficult to obtain the magnetic cores required for high-power transformers—often necessitating the use of several ferrite cores to meet power demands. In contrast, a single nanocrystalline core suffices. Although ferrite cores are significantly cheaper on a per-unit basis, the total cost of several ferrite cores ends up being higher than the price of a single nanocrystalline core.