# High – power common – mode inductance – Notes for core selection | GETWELL

However, when the two coils flow through the differential mode current, the magnetic flux in the magnetic ring cancels with each other, and there is almost no inductance.

## What should I pay attention to when choosing high power common mode inductor core?

According to the rated current, DC resistance and impedance at rated frequency of common-mode inductors, the inductor manufacturer can design according to the following steps:

1. Calculate the minimum inductance value according to the impedance

2. Select wires

3. Select common mode inductance core material and core size

4. Determine the number of turns of the coil

## The calculation formula of the minimum inductance value of the high-power common-mode inductance core is as follows:

Xl is the impedance at frequency f

The value of the choke coil inductance is divided by the load (Ohms) divided by the angular frequency or above at which the signal begins to decay.In 50 Ω load, for example, when the frequency of 4000 Hz or more signal begins to decay, then you need to use 1.99 mH (50/2 PI (4000)) of the inductor.

## Points to note during the manufacture of high-power common mode inductance core:

1. The wires made on the wireless coil core shall be insulated from each other to ensure that no breakdown short circuit will occur between the turns of the coils under the action of instantaneous overvoltage.

2. When the common mode inductance coil flows through the transient large current, the core should not be saturated.

3. The magnetic core in the high-power inductance coil shall be insulated from the coil to prevent the breakdown between them under the action of instantaneous overvoltage.

4. The common mode inductor core should be wound in a single layer as far as possible. In this way, the parasitic capacitance of the coil can be reduced and the ability of the inductor coil to impart transient overvoltage can be increased.

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Post time: Sep-01-2020