What are the functions of power inductors?

The role of power inductors

(1) Choke action: the self-induced electromotive force in the coil is always opposed to the current change in the coil. It can be divided into high frequency choke coil and low frequency choke coil.

(2) Tuning and frequency selection: inductor and capacitor in parallel can form LC tuning circuit. That is, the natural oscillation frequency of the circuit f0 is equal to the frequency f of the non-AC signal, and the inductive reactance and capacitive reactance of the circuit are equal, so the electromagnetic energy oscillates back and forth between the inductor and the capacitor, which is the resonance phenomenon of the LC circuit. When resonant, because the inductive reactance and capacitive reactance of the circuit are equivalent and reverse, the inductive reactance of the total circuit current is minimum and the current flow is maximum (refers to the AC signal of f=f0), so the LC resonant circuit has the effect of selecting the frequency, and can select the AC signal of a certain frequency.

Power inductance 6 main performance parameters

1, the main performance parameters of the power inductor are inductance L, DC resistance DCR, DC overlapping current Isat, temperature rise capacitance current Irms and self-harmonic frequency SRF.

2, inductance is the nominal inductance value of inductance, due to the existence of permeability and distributed capacitance, the inductance will change with the frequency; The precision of the inductor is generally M (±20%) file or N (±30%) file.

3, DC resistance DCR refers to the total DC resistance of the enamelled wire used between the product electrodes.

4, DC overlapping current Isat refers to the inductance in the case of continuous DC current, the inductance of the inductor will decrease, generally in accordance with the current value of 30% to set specifications.

5, temperature rise allowable current Irms refers to the inductor in the case of continuous DC current, the temperature of the inductor surface will rise, generally in accordance with the current value of 40°C to set specifications.

6, self-harmonic frequency SRF refers to the interaction between the inductor and the inductor itself, so that the inductor achieves resonance at a certain frequency, the resonant frequency is the self-harmonic frequency of the inductor, and the power inductor is required to be used below the self-harmonic frequency.

Application of power inductors

Power inductors are widely used in communication, healthcare, industry, home appliances and automotive electronics, especially automotive infotainment equipment, power transmission/safety equipment in automotive electronics. In recent years, new energy vehicles have been continuously developed, including hybrid electric vehicles (HEV), extended range hybrid electric vehicles (PHEV), pure electric vehicles (EV) and fuel cell vehicles (FCV), etc., in these new energy vehicles, the need to use different voltage levels of power systems.

The DC/DC converter has become an indispensable key component in the design and development of new energy vehicles, and the power inductor is an indispensable device for the DC/DC converter, which can provide high current and high inductance, which maintains continuous current by accumulating and releasing energy.

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