In power transmission and conversion systems, transformers are essential core equipment. The core, the "heart" of the transformer, directly determines its energy efficiency. Traditional transformer cores have long relied on silicon steel. However, with the growing demand for energy conservation, amorphous ribbon, with its unique performance advantages, has gradually become the preferred material for next-generation transformer cores. This article will analyze the underlying reasons why amorphous ribbon is an ideal material for transformer cores, from multiple perspectives including material properties, manufacturing processes, and application scenarios.
The core of a transformer is to create a magnetic circuit, enabling efficient conversion of electromagnetic energy. During this energy transfer process, energy loss in the core itself (i.e., iron loss) is a key factor affecting transformer efficiency. Data shows that transformer losses account for over 30% of total power system losses, of which core losses can reach 50%. Therefore, reducing core losses is crucial for improving energy efficiency.
Traditional transformer cores are mostly made of cold-rolled grain-oriented silicon steel (CRGO). While this has driven the development of the power industry over the past few decades, its energy-saving performance has gradually become limited. Amorphous ribbon, a new metal material with a disordered atomic arrangement and a non-crystalline structure, breaks through the performance limitations of traditional crystalline materials and provides a new solution for upgrading transformer energy efficiency. Compared with silicon steel, cores made from amorphous ribbon can significantly reduce iron loss, improve operating efficiency, and reduce energy waste and carbon emissions, offering significant advantages in addressing the dual demands of environmental protection and energy conservation.
Currently, there are two main types of mainstream materials for transformer cores: traditional cold-rolled grain-oriented silicon steel and the new generation of amorphous metal strip. Cold-rolled grain-oriented silicon steel, through precise control of crystal orientation, exhibits excellent magnetic permeability and low iron loss. Its mature production process and stable performance have long dominated the transformer core market.
Amorphous metal strip is a new material produced through ultra-rapid solidification technology. Its irregular amorphous structure with its atomic arrangement results in extremely low hysteresis losses. Microstructurally, amorphous ribbon lacks the grain boundaries and dislocations of crystalline materials, allowing for smoother magnetic domain rotation in response to magnetic field changes, significantly reducing energy loss.
Amorphous ribbon offers particularly significant advantages in core performance indicators. Data shows that the core loss of amorphous ribbon is only 1/3 to 1/5 that of cold-rolled grain-oriented silicon steel. This means that under the same operating conditions, amorphous core transformers significantly reduce energy waste.
From an application perspective, amorphous ribbon cores perform particularly well in distribution transformers, effectively reducing grid line losses; improving energy conversion efficiency in renewable energy generation systems; and supporting efficient power dispatch in smart grid construction. Choosing amorphous ribbon is essentially a long-term energy conservation and sustainable development strategy. While the initial cost may be slightly higher, the lifecycle energy savings far outweigh the investment.
Traditional transformer cores are made by stacking cold-rolled grain-oriented silicon steel sheets. During the manufacturing process, the silicon steel sheets are cut into specific shapes and staggered to reduce air gaps in the magnetic circuit, thereby lowering magnetic resistance. However, the inherent thickness of the silicon steel sheets and their crystal structure limit further improvements in magnetic performance. The air gaps that inevitably form during the lamination process also increase losses.
The manufacturing of amorphous ribbon cores begins with breakthroughs in material preparation. Utilizing ultra-rapid solidification technology, the molten alloy is cooled at a rate of one million degrees Celsius per second. This prevents the atoms from aligning themselves, forming an amorphous structure. This results in a thin ribbon just 20-30 microns thick. This ultra-thinness fundamentally reduces eddy current losses, which are proportional to the square of the material thickness.
During the core forming stage, the amorphous ribbon is precision-cut and then stacked through a specialized process to create a closed magnetic circuit. The manufacturing process requires strict control over lamination accuracy to minimize air gaps and maintain optimal magnetic properties. Advanced manufacturing techniques ensure the consistency and reliability of amorphous cores, enabling them to meet the demanding requirements of large-scale power equipment applications.
Transformer cores can be categorized into three types based on their structural design. Amorphous ribbon, with its excellent magnetic properties, offers high efficiency advantages in all designs.
Core-type cores are characterized by windings wrapped around the outer core legs, resulting in a simple structure and easy manufacturing. They are widely used in power transformers. Core-type cores made of amorphous ribbon can effectively reduce magnetic circuit losses and improve transformer operating efficiency, making them particularly suitable for medium- and large-capacity distribution transformers.
Shell-type cores feature a structure where the windings are surrounded by the core, resulting in low leakage flux and high mechanical strength. They are commonly used in specialty transformers. The low loss characteristics of amorphous ribbon combined with the low leakage flux advantages of the shell structure can further reduce energy waste and improve equipment stability.
Toroidal cores are closed circular structures with a uniform and continuous magnetic circuit, offering extremely high efficiency and compact size. They are commonly used in precision instruments and small transformers. The flexibility of amorphous ribbon makes it easy to bend and form, resulting in toroidal cores with superior magnetic properties, making them particularly suitable for miniaturized, high-efficiency equipment.
Overall, amorphous ribbon cores are adaptable to a variety of structural designs. Their energy-saving advantages are particularly pronounced in distribution transformers, providing strong support for reducing grid losses.
The performance of a transformer depends not only on the core, but also on the choice of winding material. Currently, the mainstream winding materials are copper and aluminum. Copper has high conductivity and excellent mechanical properties, resulting in low losses and high reliability, making it commonly used in high-end transformers with stringent performance requirements. Aluminum, on the other hand, boasts lightweight and low cost, making it widely used in large-scale power grid transformers, reducing overall equipment costs.
However, it should be noted that the winding material primarily affects copper losses (load losses), while the core material determines iron losses (no-load losses). No-load losses are a perennial component of a transformer's total losses, occurring continuously regardless of load level. Amorphous ribbon cores significantly reduce no-load losses, fundamentally improving transformer energy efficiency. Therefore, compared to the winding material, the core material has a more critical impact on the long-term operating efficiency of a transformer, which is the core reason why amorphous ribbon cores stand out.
Transformer core heating is primarily due to hysteresis losses and eddy current losses. When an iron core is repeatedly magnetized in an alternating magnetic field, magnetic domains continually flip, generating hysteresis losses. Simultaneously, eddy currents are induced within the core, and the current flowing through resistors generates eddy current losses. Both losses are ultimately released as heat, causing the core temperature to rise.
Compared to traditional silicon steel cores, amorphous ribbon cores have significantly reduced hysteresis and eddy current losses, generating significantly less heat during normal operation. However, in practice, amorphous cores may still experience abnormal heating, primarily due to design flaws or improper use.
In design, excessive air gaps or loose stacking between core laminations can increase magnetic resistance and excess losses, leading to localized heating. Inadequate cutting precision or improper insulation during manufacturing can also cause concentrated eddy current heating. During operation, prolonged transformer overload or cooling system failures can cause heat accumulation in the core, leading to elevated temperatures.
Advanced manufacturing processes and strict quality control effectively prevent design flaws and manufacturing errors in amorphous cores. Precise lamination technology minimizes air gaps, high-quality insulation coatings reduce eddy currents, and comprehensive testing procedures ensure product performance. These measures not only minimize core heating but also extend the transformer's service life, ensuring long-term stable operation.
Choosing amorphous ribbon as a transformer core material is an inevitable choice for the energy sector's pursuit of high efficiency, energy conservation, and sustainable development. Its significant advantages include: significantly reduced core losses, improving transformer operating efficiency; reduced energy waste and carbon emissions, contributing to environmental protection goals; and significantly lower long-term operating costs, resulting in significant lifecycle economic advantages.
Although the initial investment in amorphous ribbon cores is slightly higher than that of traditional silicon steel cores, the long-term value of the energy savings and extended lifespan far outweighs the initial cost. As manufacturing technology matures and its application scale expands, amorphous ribbon will undoubtedly play a more important role in the transformer industry, driving the development of a more efficient and greener power system.