With the development of high-speed motors, how to reduce the iron loss of the motor has become the focus of attention in academia and industry. Amorphous alloys have been gradually applied to high-speed motors due to their high frequency and low iron loss characteristics. However, due to their low saturation flux density, As a result, the motor torque is greatly limited.
When the amorphous alloy is formed, a large internal stress is generated in the material due to the rapid temperature change1. Usually, annealing treatment is required to eliminate the influence of internal stress on magnetic properties. During the annealing treatment of amorphous transformer cores, a magnetic field is usually applied in the direction of the magnetic circuit to improve the state of the magnetic domain, increase the saturation magnetic flux density in this direction and reduce the iron loss2. However, the magnetic field annealing technology has not been applied to the field of motors. In this paper, the amorphous material processed by this process is made into the shape of stator teeth, and the stator yoke is spliced with non-magnetic field annealing to form a complete stator core, as shown in Figure 1. Show. Since the magnetic field of the tooth is a pulsed magnetic field, this technology can effectively reduce the iron loss of this part and increase the motor torque to a certain extent.
In order to reduce the difficulty of motor processing and the loss caused by many splicing positions, the motor structure is further optimized. As shown in Figure 2, the motor stator is composed of four parts with the same structure, and the teeth of each part are approximately parallel to the magnetization direction. However, due to the fact that the magnetic field of the yoke part is not always consistent with the direction of the magnetic field treatment in the actual motor operation, the iron loss of the stator yoke part of this structure is slightly larger than that of the stator structure without magnetic field treatment. The structure of the ratio realizes the optimal distribution of iron loss and performance improvement.
References:
1Sato, T., & Todaka, T. (2018). Effect of magnetic annealing on magnetic characteristic of amorphous wound core. IEEE Transactions on Magnetics, 54(11), 1-4.
2Gao Jie, He Chengxu, Song Wenle, Yang Fuyao, Liu Yang. Effects of Longitudinal Magnetic Annealing Treatment and Tensile Stress on Magnetization Characteristics and Loss of 1K101 Amorphous Alloy Ribbon J. Metal Heat Treatment, 2022,47(03):39-43 .

Fig.1 Four splicing schemes and stator punching

Fig.2 Magnetic properties test samples of amorphous alloys