The role of inductive coil in switching power supply, let alone not know
Time:2022-12-13
Views:199
Inductive coil is a common component in switching power supply. Because its current and voltage phases are different, its loss is zero theoretically. Inductance coil is often used as energy storage element, and it is also used in input filter and output filter circuit together with capacitor to smooth current.
Inductive coil is also called choke coil, which is characterized by "great inertia" of the current flowing through it In other words, due to the continuous magnetic flux, the current on the inductance coil must be continuous, or a large voltage spike will occur.
Inductance coil is a magnetic element, which naturally has the problem of magnetic saturation. Some applications allow inductance saturation, some applications allow inductance coil to enter saturation from a certain current value, and some applications do not allow inductance saturation, which requires differentiation in specific lines.
In most cases, the inductance coil operates in the "linear zone", where the inductance value is a constant and does not change with the terminal voltage and current. However, switching power supply has a problem that can not be ignored, that is, the winding of inductance will lead to two distributed parameters (or parasitic parameters), one is the inevitable winding resistance, the other is the distributed stray capacitance related to the winding process and materials. Stray capacitance has little effect at low frequency, but it gradually shows up with the increase of frequency. When the frequency is higher than a certain value, the inductance coil may become capacitive. If the stray capacitance is "concentrated" into a capacitor, the capacitance characteristic after a certain frequency can be seen from the equivalent circuit of the inductance coil.
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