common mode choke
Common-mode choke: In the common filter, usually only one common-mode choke is installed, and the leakage inductance of the common mode choke is used to generate an appropriate amount of differential mode inductance, which can inhibit the differential mode current. Sometimes, artificially increasing the leakage inductance of a common-mode choke increases the differential mode inductance (think about how you can increase the leakage inductance). The inductance of common-mode chokes ranges from 1mH to tens of mH, depending on the frequency of interference to be filtered. The lower the frequency, the greater the inductance required.
In the general filter, the function of common-mode choke is mainly to filter out low-frequency common-mode interference. At high frequency, due to the existence of parasitic capacitance, the suppression effect on interference has been small, and the common mode filter capacitor is mainly relied on. Due to the limitation of leakage current, sometimes common mode filter capacitor is not used in medical equipment. In this case, high frequency characteristics of choke coil should be improved.
