Why is an air gap used in an inductor?
In the case of a transformer or inductor, the air gap only reduces the slope of the B/H loop, reducing permeability and inductance, and hence increasing the magnetizing current in the primary. Thus, in the transformer example, the gap is used to reduce the inductance (perhaps for resonant applications).
How will the core material affect the inductor design?
The core material, as well as the core geometry, affect the core’s “effective permeability”. For a given core shape, size and material, and a given winding, higher permeability magnetic materials result in higher inductance values as opposed to lower permeability materials.
Why are discrete gaps used in magnetic inductors?
Discrete gaps also result in inductors that are vulnerable to eddy current losses in the coil due to fringing, and to generating EMI. Discrete gaps are also used in amorphous and nanocrystalline tape wound cut cores, which have improved AC loss performance compared with powder cores, but often at a cost disadvantage.
How are power inductor cores separated from each other?
The power inductor gap may be realized in one of two fashions, discrete or distributed. Distributed gap materials are powder cores. At a microscopic level, magnetic alloy powder grains are separated from one another by binder insulation or by high temperature insulation coating each grain.
Why are iron powder cores used in inductors?
Iron powder cores have found wide use when core loss is a consideration. When compared to other magnetic materials, such as ferrites, the distributed air gap allows powder cores to store higher levels of magnetic flux. The distributed air gap also allows higher dc current levels before saturation occurs.
Why is core density important in an inductor?
The combination of winding turns and volume of magnetic material sets an upper limit on the maximum allowable magnetic flux a core can sustain. Flux density is important because it’s related to energy. Higher flux densities imply greater amounts of stored energy.