Core material, air gap and the magnetic flux density on the influence of the core reactor
Core material, air gap and the magnetic flux density on the influence of core reactor is 2019 -
An iron core reactor winding circle number unchanged, and core materials by hot rolled electrical steel pieces instead of cold rolled electrical steel sheet, reactance value change, but the situation is different.
Because of the core under the same magnetic flux density, cold rolled electrical steel piece of high permeability than hot rolled.
For core reactor with no air gap reactance value and magnetic conductivity is proportional to the, so hot rolled steel instead of cold rolled steel slices reactance value will rise;
For core reactor with air gap, the winding parameter of a given case, the size of its reactance value is mainly determined by the air gap size.
, because of the large air gap magnetic resistance under the condition of the same magnetic flux need more magnetomotive force, so the core material from hot to cold rolling, the reactance value increase, but the saturation magnetic flux density have change, magnetic flux density in the iron core is low.
In the core with the air gap, the main magnetic flux through core column of air gap, the edge effect and spread out (
As shown in figure 1 a)
, resulting in additional loss.
A large proportion of the edge of the magnetic flux perpendicular to the side of the core section into the core column, therefore in the core which produce large eddy current loss.
In order to reduce the loss, will minimize the height of each air gap, to keep it in the following 10 mm, to reduce the height of each core section, it is advisable to make it less than 50 mm.
Figure 1 core air-gap structure (
And radiation shape core section of the larger core reactor should be adopted as shown in figure 1 b radiation shape core section, making the edges of the diffusion flux in the core section, along the entire core circle around is to make sure that the end verticality and iron chips, so as to reduce the eddy current loss.
Select core reactor should be considered when the magnetic flux density of running time, vibration, noise, temperature rise and loss, etc.
Start the reactor or arc suppression coil, for example, because of its running time is short, although core loss bigger, core temperature rise is not too high, so the magnetic flux density can be obtained.
But at this point the vibration and noise of iron chip increases with a square relationship with magnetic flux density.
Thus, selecting magnetic flux density of the above factors must be taken into account.
In order to reduce vibration and noise of core reactor, it is necessary to adopt proper compaction structure, core and winding to make pressure.
So, between the winding and iron core column to adopt tide plate tight, to ensure the winding wheel to not move, and make every core section vertical concentric with each other.
As for winding and iron core axial fastening should use stick and nail structure, as shown in figure 2.
Figure 2 core reactor pressure structure at this point, through the rod core section of fastening, can be make the core as a whole.
And then through the nail winding tighten.
But should pay attention to the influence of magnetic flux leakage of tie rod.