Analysis of the Causes of Large Iron Core Loss
The core loss is mainly determined by the basic iron loss, the core loss is too large, or the material is deviated from the design or the magnetic flux density is high due to many undesirable factors in the production, and the silicon steel sheet is short-circuited to increase the thickness of the silicon steel sheet.
Silicon steel sheet quality does not meet the requirements
As the main magnetic conductive material of the motor, the silicon steel sheet has great influence on the performance of the motor. The scam is to ensure that the grade of the silicon steel sheet meets the design requirements. In addition, the material properties of different manufacturers of the same grade of silicon steel sheet have certain differences. When selecting materials, you should try your best to select the materials of good silicon steel manufacturers.
Insulation between stator iron chips is not good
There are many factors that cause poor insulation between the sheets, the quality of the silicon steel sheet itself, and the human factors caused by the iron core manufacturing process.
●The silicon steel sheet is not insulated or untreated. This is the material problem of silicon steel sheet. This kind of problem can be found in the inspection process of silicon steel sheet, but not all motor manufacturers have this test item. This problem is often not well recognized by motor manufacturers.
● Damage between sheets is damaged or short between sheets and sheets. This type of problem occurs in the manufacturing process of the core. If the pressure of the iron core is too large, the insulation between the sheets is broken; or the burrs are too large after the punching, and the burrs are removed by grinding, which causes the surface insulation of the punch to be seriously damaged; The rear groove is not only in the repair mode; or it is corrected by the turning method due to the fact that the stator is not smashed, the stator inner cymbal and the base seat are not concentric. The usual usage of these motor production processes has a great impact on the performance of the motor, especially the iron loss.
●When the winding is removed by fire or electric heating, the iron core is overheated, and the magnetic permeability is deteriorated and the insulation between the sheets is damaged. This problem mainly occurs during the repair of the windings in the production process and the repair of the motor.
● Stacking and other processes will also cause insulation damage between the laminations and increase eddy current loss.
●The iron weight is not compacted between the sheets. The end result is that the weight of the core is insufficient, and the most direct result is that the current is out of tolerance and the iron loss is exceeded.
● The silicon steel sheet is too thick and the magnetic circuit is too saturated. At this time, the relationship between the no-load current and the voltage is curved more severely. This is also a key element in the production and processing of silicon steel sheets.
● During the production and processing of iron core, the grain orientation of the silicon steel sheet punching and shearing surface attachment will be destroyed, resulting in the increase of iron loss under the same magnetic induction. For the variable frequency motor, the additional iron loss caused by harmonics is also considered; this is the design link. Factors that should be considered together.
● Other. In addition to the above factors, the design value of the motor iron loss should be integrated with the actual production and processing of the iron core, and try to achieve the fit between the theoretical value and the actual value. The characteristic curves provided by the general material supplier are measured according to the Epstein square circle method, and the magnetization directions of different parts of the motor are different. This special rotating iron loss is currently unconsidered. This will result in inconsistencies between the calculated and measured values to varying degrees.
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