Main Characteristic Parameters Of Inductor

1. Nominal inductance: The size of the inductance indicated on the label. Representing the inherent characteristics of the coil itself, it mainly depends on the number of coils, structure, and winding method of the coil, and is independent of the current size. It reflects the ability of the inductance coil to store magnetic field energy and also reflects the ability of the inductor to generate induced electromotive force when changing the current. The unit is Heng (H).

2. Allowable error: The maximum allowable deviation range of the actual inductance of the inductor relative to the nominal value is called the allowable error.

3. Inductive reactance XL: The magnitude of the resistance of an inductive coil to AC current is called inductive reactance XL, measured in ohms. Its relationship with inductance L and AC frequency f is XL=2 π fL.

4. Quality factor Q: A physical quantity representing the quality of a coil, where Q is the ratio of inductance XL to its equivalent resistance, i.e. Q=XL/R The higher the Q value of the coil, the smaller the loss of the circuit. The Q value of the coil is related to factors such as the DC resistance of the wire, the dielectric loss of the skeleton, the loss caused by the shielding cover or iron core, and the influence of high-frequency skin effect. The Q value of the coil is usually in the tens to hundreds.

5. Rated current: Rated current refers to the working current that can ensure the normal operation of the circuit.

6. Nominal voltage

7. Distributed capacitance (parasitic capacitance): The capacitance between the turns of a coil, between the coil and the shield, and between the coil and the substrate is called distributed capacitance. The existence of distributed capacitance reduces the Q value of the coil and deteriorates its stability. Therefore, the smaller the distributed capacitance of the coil, the better. The use of segmented winding method can reduce distributed capacitance.

8. Self resonant frequency (the frequency at which Q is the maximum): When the frequency is very high, the inductance is no longer treated as a lumped parameter, and the influence of parasitic parameters cannot be ignored. Parasitic parameters include Rac equivalent series resistance (ESR) and Cs equivalent parallel inductance (ESL).