What are the main performance indexes of inductance coil
Information from:internet Published on:2022-03-02
The performance index of inductance coil is mainly the inductance. In addition, the wire winding the inductance coil generally has a certain resistance, which is usually very small and can be ignored. However, when the current flowing through some circuits is large, the small resistance of the coil can not be ignored, because a large current will consume power on the coil, causing the coil to heat or even burn out. Therefore, sometimes the electric power that the coil can bear should be considered. Inductance The inductance L represents the inherent characteristics of the coil itself, which is independent of the current. Except for the special inductance coil (color coded inductance), the inductance is generally not specially marked on the coil, but marked with a specific name. Inductance, also known as self inductance coefficient, is a physical quantity indicating the self induction ability of the inductor. The inductance of inductor mainly depends on the number of turns (turns) of coil, winding mode, whether there is magnetic core and the material of magnetic core, etc. The larger the number of coils, the denser the number of coils. The inductance of a coil with a magnetic core is greater than that of a coil without a magnetic core; The greater the permeability of the core, the greater the inductance of the coil. The basic unit of inductance is Henry, which is represented by the letter "H". The commonly used units are milli Heng (MH) and micro Heng（ μ H) , the relationship between them is: 1H=1000mH 1mH=1000 μ H Inductive resistance The size of the blocking effect of the inductive coil on the AC current is called inductive reactance XL. The unit is Ohm and the symbol is Ω. Its relationship with inductance L and AC frequency f is XL = 2 π fl Quality factor The quality factor Q is a physical quantity indicating the coil quality. Q is the ratio of inductive reactance XL to its equivalent resistance, i.e. q = XL / R. It refers to the ratio of the inductive reactance and its equivalent loss resistance when the inductor works under the AC voltage of a certain frequency. The higher the Q value of the inductor, the smaller the loss and the higher the efficiency. The Q value of the coil is related to the DC resistance of the conductor, the dielectric loss of the skeleton, the loss caused by the shield or iron core, and the influence of high-frequency skin effect. The Q value of the coil is usually tens to hundreds. The quality factor of inductor is related to the DC resistance of coil conductor, the dielectric loss of coil skeleton and the loss caused by iron core and shield. distributed capacitance For any inductive coil, there are certain capacitances between turns, between layers, between coil and reference ground, between coil and magnetic shield, etc. These capacitances are called the distributed capacitance of inductive coil. If these distributed capacitors are combined, it becomes an equivalent capacitance C connected in parallel with the inductance coil. The existence of distributed capacitance reduces the Q value of the coil and worsens the stability. Therefore, the smaller the distributed capacitance of the coil, the better. Rated current Rated current refers to the maximum current allowed to pass through when the inductor works normally. If the working current exceeds the rated current, the performance parameters of the inductor will be changed due to heating, and even burned due to overcurrent. Allowable deviation Allowable deviation refers to the allowable error between the nominal inductance and the actual inductance on the inductor. Inductors commonly used in circuits such as oscillation or filtering require high precision, and the allowable deviation is ± 0.2 [%] ~ ± 0.5 [%]; However, the accuracy of coils used for coupling and high-frequency current blocking is not high; The allowable deviation is ± 10 [%] ~ 15 [%].
