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The advantages and disadvantages of using toroidal cores for common mode inductors
- 2020-07-02-

Xiaoao will share with you todayCommon mode inductanceThe advantages and disadvantages of using toroidal cores may not be well understood by these two power products, so the knowledge will be increased next.

As we all know, in computer switching power supplies, common mode inductors are commonly used to filter out common mode EMI signals. First, the unit fundamental frequency of the switching power supply plus high-frequency harmonics generates noise. In other words, noise will exist in the range of 10kHz to 50MHz. Therefore, the inductor must have a wider frequency range and high impedance characteristics. The total impedance of a common mode inductor consists of two parts: series inductance (XS) and series resistance (RS). At low frequencies, impedance is inductive reactance. The effective permeability and inductance decrease with increasing frequency. (See Figure 3.) The interaction of series inductance (XS) and series resistance (RS) produces acceptable impedance (ZS) across the entire bandwidth. So how to choose its core? Today, let’s talk about it from the editor of Shenzhen Chenfei Electronics

For most products, ferrites (nickel-zinc series and manganese-zinc series) are used as the core of common mode inductors. The nickel-zinc core is characterized by low initial permeability, but it can still maintain the initial permeability at very high frequencies (greater than 100MHz). On the contrary, the Mn-Zn system has a higher initial permeability, but when the frequency is very low (20kHz), the permeability may decrease. Due to the low initial permeability of Ni-Zn magnetic cores, high impedance cannot be generated at low frequencies. However, MnZn cores can provide very high impedance characteristics at low frequencies and are very suitable for electromagnetic interference from 10 kHz to 50 MHz. Based on this, this article studies the manganese-zinc magnetic core.

The above is Xiaoao rightCommon mode inductanceHave you learned the summary of the advantages and disadvantages of using toroidal cores? Aolite Technology Co., Ltd. integrates independent research and development, production and sales. Professionally provide electronic components and passive components such as protection devices, common mode inductors, resistance capacitors, diodes, flat inductors, sensors, power sockets, chip fuses, hardware, etc.

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