Power Inductor power loss
During the exchange cycle, energy loss due to changes in the magnetic energy of the core power inductance is the difference between the on-time magnetic energy stored in the core and the magnetic energy extracted by the core at shutdown. Therefore, the total energy stored in the core is the shadow area of the B-H loop in Figure 2 multiplied by the volume of the core. When the power inductance current drops, the magnetic field strength decreases, and the magnetic flux density changes along the different paths in Figure 2 (according to the direction of the arrow), most of which will enter the load, and the difference between the stored energy and the emitted energy is the energy loss. The energy loss of the core is the area drawn by the B-H loop multiplied by the volume of the core, and this energy multiplied by the switching frequency is the power loss. Hysteresis loss depends on the function, for most ferrite materials, n is about 2.5 to 3, but this is only effective if the core does not become saturated, and the exchange frequency falls within the specified operating range. The shaded area in Figure 2 shows that the first quadrant of the B-H loop is the operating region of the flux density, because most boost and buck converters operate at positive inductance currents.
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