How to reduce hysteresis loss of transformer

　　irst, understand the mechanism of hysteresis loss.

Hysteresis loss comes from the energy consumed by repeated arrangement of magnetic domains in the process of periodic magnetization of ferromagnetic materials. Its magnitude is related to the variation amplitude and frequency of magnetic induction intensity and the hysteresis loop area of iron core material. According to Steinmetz empirical formula, hysteresis loss can be expressed as:

$$

P_h = k_h cdot f cdot B_m^n

$$

Where $P_h$ is the hysteresis loss, $k_h$ is the material constant, $f$ is the frequency, $B_m$ is the maximum magnetic induction intensity, and $n$ is the Steinmetz index (generally between 1.5 and 2.5). Therefore, it can be seen from the formula that the reduction of hysteresis loss can be started from many aspects such as material selection, working frequency and design structure.

Second, methods to reduce hysteresis loss
　　. Select high-performance iron core materials.

The choice of materials is the key to reduce hysteresis loss. Traditional silicon steel sheets are widely used in transformer cores because of their good magnetic conductivity. In recent years, with the development of new materials, new soft magnetic materials such as amorphous alloys and nanocrystalline alloys are gradually applied to high-efficiency transformers. These materials have lower coercivity and narrower hysteresis loop, thus significantly reducing hysteresis loss.

2. Optimize the design of magnetic induction intensity

Magnetic induction intensity $B_m$ has great influence on hysteresis loss. The operating point of $B_m$ should be selected reasonably in the design, so that it can operate in the region with low hysteresis loss. Generally speaking, the magnetic induction intensity should not be too high to avoid entering the saturation region, and it should not be too low to avoid increasing the volume and cost of the core.

3. Control the working frequency

Hysteresis loss is proportional to frequency. Therefore, in high-frequency situations, core materials or design structures that are more suitable for high-frequency work should be adopted. For example, ferrite material is often used in switching power supply transformers because of its low hysteresis loss at high frequency.

4. Laminated structure is adopted to reduce eddy current loss and indirectly affect hysteresis loss.

Although laminated structure is mainly used to reduce eddy current loss, reasonable laminated design is also helpful to improve magnetic flux distribution, thus indirectly reducing hysteresis loss. For example, the use of thinner and better insulated silicon steel sheet stacked cores can effectively reduce eddy current and local hysteresis.

5. Improve the level of manufacturing technology

The machining process of iron core (such as punching, shearing and welding) may cause mechanical stress of materials, leading to the decline of magnetic properties. By optimizing the manufacturing process, such as laser treatment and heat treatment, the internal stress can be reduced, the magnetism of the material can be restored, and the hysteresis loss can be reduced.
　　Third, the conclusion

With the improvement of energy conservation and environmental protection awareness, reducing hysteresis loss in transformers has become an important topic to improve the energy efficiency of power equipment. By means of material selection optimization, design improvement and process improvement, the hysteresis loss can be significantly reduced, and the overall operation efficiency of the transformer can be improved. In the future, with the development of new magnetic materials and advanced manufacturing technology, the energy efficiency level of transformers is expected to be further improved, providing strong support for building a green and efficient power system.