What is the difference between ESR and DCR?

leonzheng

已于 2023-07-20 18:05:40 修改

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于 2023-07-20 17:46:49 首次发布

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文章讨论了电感器中的两种电阻来源——直流电阻(DCR)和交流电阻(ESR)。ESR是DCR与AC电阻之和，AC电阻主要由铜的涡流损失、邻近效应和Skin效应引起。频率和线径对AC电阻有显著影响，线径增加时，AC电阻也会增加。当电感器接近磁饱和时，其电感量会下降。

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https://electronics.stackexchange.com/questions/594519/what-is-the-difference-between-esr-and-dcr

An inductor has two sources of resistance (real part), DC and AC.
The ESR your LCR meter is measuring is DC + AC resistances.

DC resistance is what you measure using a DC ohmmeter (most DMMs use DC).

AC resistance is due to copper eddy losses due proximity effect (due to magnetic field induced by adjacent conductors) and skin effect (due to magnetic field around the conductor). There is also loss due to the core, but that usually will be low when when measuring with low level signals. Below 1 MHz, skin effect losses are generally insignificant and proximity effect losses will dominate. Proximity effect losses are proportional to $frequency^2$ and $wire\_diameter^4$ . An odd thing comes out of the equations which says that the AC resistance increases as the wire diameter increases. Experiments I have done show this to be true. If operating at a single frequency, there is an optimal wire diameter which minimizes AC+DC resistance. The equations and references for proximity effect can be found in this post.

[Edit] DC current through the inductor affects the inductance. When you get close to saturation of the core, the inductance will trend downwards. The inductance versus DC current is sometimes shown as a graph in data sheets.