Reasons for excessive losses in manufacturing processes

As the main magnetic material of motors, the performance compliance of silicon steel sheets has a great impact on the performance of motors. The main purpose is to ensure that the grade of silicon steel sheets meets the design requirements. In addition, there are certain differences in material performance among different manufacturers of silicon steel sheets of the same grade. When selecting materials, efforts should be made to choose materials from good silicon steel manufacturers. Below are some key factors that have actually affected iron consumption encountered before.

Silicon steel sheets have not undergone insulation treatment or have not been properly treated. This type of problem can be detected during the testing process of silicon steel sheets, but not all motor manufacturers have this testing item, and this problem is often not well identified by motor manufacturers.

Damage to inter chip insulation or short circuit between chips. This type of problem occurs during the manufacturing process of the iron core. If the pressure during the stacking of iron cores is too high, it will cause insulation damage between the pieces; Or if the burrs are too large after punching, they can be removed by grinding, resulting in severe damage to the insulation on the surface of the punched sheet; After the completion of the iron core stacking, the groove is not smooth, and the filing method is used; Or due to factors such as uneven stator bore or non concentricity between stator bore and machine base stop, turning method may be used for correction. The common usage in the production and processing of these motors actually has a great impact on their performance, especially iron loss.

When dismantling the winding using methods such as fire or electric heating, the iron core overheats, causing a decrease in magnetic conductivity and damage to the insulation between the pieces. This problem mainly occurs during the repair of windings and motors in the production and processing process.

Stacking welding and other processes can also cause insulation damage between stacked pieces, increasing eddy current losses.

Insufficient iron weight and lack of compaction between sections. The ultimate result is that the weight of the iron core is insufficient, which can directly lead to current deviation and iron loss exceeding the standard.

The excessive coating of silicon steel sheets can cause the magnetic circuit to become too saturated, resulting in a more severe bending of the relationship curve between no-load current and voltage. This is also a key element in the production and processing process of silicon steel sheets.

During the production and processing of iron cores, it can cause damage to the grain orientation of the punching and shearing surface attachments of silicon steel sheets, resulting in an increase in iron loss under the same magnetic induction; For variable frequency motors, additional iron loss caused by harmonics should also be considered; This is a factor that should be comprehensively considered in the design process.

There are many ways to reduce iron consumption in engineering, and the most important one is to prescribe the right medicine. Of course, it's not just a matter of iron consumption, other losses are the same. The most fundamental way is to know the reasons for the high iron loss, such as high magnetic density, high frequency, or severe local saturation. Of course, in the normal way, on the one hand, it is necessary to approach reality as closely as possible from the simulation side, and on the other hand, process coordination technology should be used to reduce additional iron consumption. The most common way is to increase the use of high-quality silicon steel sheets, and if cost is not considered, imported super silicon steel can be chosen. Of course, with the development of domestic new energy drive technology, it has also driven better development in the upstream and downstream. Domestic steel mills are also launching specialized silicon steel products. Genealogy has a good product classification for different application scenarios. Here are a few straightforward methods to encounter:

Optimize magnetic circuit

Optimize the magnetic circuit, more precisely, optimize the sinuosity of the magnetic field. This is crucial, not only for fixed frequency induction motors. Variable frequency induction motors and synchronous motors are crucial. When I was working in the textile machinery industry, I made two motors with different performance to reduce costs. Of course, the most important one was the presence or absence of skewed poles, which resulted in inconsistent sinusoidality of the air gap magnetic field. Due to working at high speeds, iron consumption accounts for a large proportion, resulting in a significant difference in losses between the two motors. After a series of backward calculations, the iron consumption of the motors increased by more than twice due to the control algorithm. Here is also a reminder that when making a variable frequency speed regulating motor, it is necessary to couple the control algorithm.

Reduce magnetic density

Increasing the length of the iron core or increasing the magnetic flux area of the magnetic circuit to reduce the magnetic flux density, but the amount of iron used in the motor increases accordingly;

Reduce the thickness of the iron chip to minimize the loss of induced current

If cold-rolled silicon steel sheets are used instead of hot-rolled silicon steel sheets, the thickness of the silicon steel sheets can be reduced, but thin iron sheets will increase the number of iron sheets and the manufacturing cost of the motor;

Using cold-rolled silicon steel sheets with good magnetic conductivity to reduce hysteresis loss;

Adopting high-performance iron chip insulation coating;

Heat treatment and manufacturing technology

The residual stress after iron chip processing will seriously affect the loss of the motor. When processing silicon steel sheets, the cutting direction and punching shear stress have a significant impact on the loss of the iron core. Cutting along the rolling direction of silicon steel sheets and performing heat treatment on silicon steel stamping sheets can reduce losses by 10% to 20%.