Let us introduce you chokes, in fact it’s a transformer with one winding.
Chokes are usually used as differential filters for EMI interference and as energy accumulators in high-frequency converters. Accumulation occurs according to the scheme of transformers (electromagnetic communication). They are different in size – it depends on the amount of energy that is needed for storage or conversion. Can be made both on ring and rod cores. By material, there are composite, powder, ferrite, nanocrystalline and amorphous types.