A method to reduce leakage inductance problem of toroidal transformer

The leakage inductance of the toroidal transformer = magnetic leakage. The greater the magnetic leakage, the worse the efficiency of the transformer. For example, the larger the magnetic leakage of the audio transformer, the sound quality will be affected. So the leakage inductance problem is also our concern. So how to reduce the leakage inductance problem of the transformer? The main reason for the magnetic leakage is that the magnetic flux of the iron core does not fully participate in the coupling between the primary and the secondary, and a small part forms a loop outside the iron core, so a large part of the magnetic leakage is The reason is because of the iron core. Therefore, in order to reduce the magnetic flux leakage problem, we must first start from the iron core.

We can know that the better the iron core material and the better the craftsmanship, the smaller the magnetic flux leakage and the higher the efficiency. Therefore, choosing high-quality iron core materials can reduce the magnetic flux leakage. Such as silicon steel sheet iron core material: silicon steel sheet is divided into b1 super material, b1 material, B1 material, B4 material, B4 material, A material, H material, the thinner the thickness of the silicon steel sheet, the better the core quality.

When the iron core is fixed, other parameters are also fixed. The size and cross-sectional area of ​​the iron core are no problem, and its magnetic permeability will not be too high. At this time, it is necessary to increase the number of turns of the primary coil to meet the requirements of the transformer for the inductance, but the number of turns of the coil is proportional to the leakage inductance, and the leakage inductance of the coil will increase accordingly. So we need to reduce the frequency to reduce the leakage inductance, which can be reduced to 35~40Hz.

The relative position and interval between the primary and the secondary will also produce magnetic flux leakage, so to reduce the magnetic flux leakage, the primary and secondary coils should be wound evenly and evenly on the core.

Therefore, if you want to reduce the leakage inductance, you can first start with the iron core material, and then you can start with the number of coil turns.