Common-mode chokes are for filtering high-frequency interferences. Because of their function, they are an indispensable part of any system that converts electricity.
Used at the inputs and outputs of electronic circuits, they act as a barrier to interferences (disturbances), both external and those emitted by the electronic circuit. Common-mode chokes are an indispensable part of any electricity conversion system. Together with additional components, common-mode chokes form filter stages.
Filter systems at the interfaces of converters are used in renewable energy conversion systems, car chargers, battery power systems, railway converters, grid power supplies, electric drives, etc.