High Voltage Common Mode Choke

When the noise terminal voltage is measured under the initial conditions we can see that a noise spectrum occurs at multiples frequency is converted to n multiples of the 500 khz switching frequency.

High voltage common mode choke.

The common mode voltage noise terminal voltage was measured for one line with respect to ground using an artificial mains network amn. Inductance values up to 125 mh. In this video we explain how a common mode choke works and how the leakage inductance of a common mode choke can help us filter differential mode noise. Common mode choke is usually used in a power supply to filter out noise from the incoming line voltage.

1250 vrms one minute isolation between windings. There is no heating or power dissipation since its only current and the voltage across the winding is zero thus the power is zero. Figure 9 4b shows the physical form of an actual choke. The common mode currents i1 and i2 flowing in the same direction through each of the choke windings creates equal and in phase magnetic fields which add together.

A typical common mode choke configuration. Common mode choke inductor design the common mode choke is one of the many types of inductors. Common mode noise will be neutralized when it passes through a commom mode choke. This is done either by paralleling the wires or by twisting them together prior to winding.

Figure 9 4a shows the schematic symbol. In general common mode chokes may introduce signal integrity issues and other unexpected results in the can network. Impedance of an inductor is usually specified as a minimum in ohms at the desired frequency. Low profile and high voltage ratings can also be realized by the common mode chokes of the we cmb family.

Current ratings as high as 15 amps. The turns of the common mode choke are wound in the bifilar manner i e they are wound together. Only current electro magnetic flux through its coupling ferrite core are cancelled out in the common mode choke 1 1 current transformer. The we cmbnc is a vde certified series of common mode chokes with a highly permeable nanocrystalline core material.

Impedance is the most important aspect of a common mode choke. Our extensive inductance values as low as 0 075 uh to 142 mh and low leakage inductance common mode choke designs gives our customers a wide variety to choose from. One of the most severe unexpected consequences from common mode choke use is the extremely high transient voltages that may be generated by the inductive flyback during a short circuit of a can bus line to a dc voltage. Highest common mode impedance over the widest frequency range.

Figure 9 4 shows a common mode choke that is useful for emi up to about 30 mhz or so. Dielectric withstanding voltage as high as 4 750 volts to comply with international safety standards.