DC/DC switching power supply input active differential mode filtering device and filtering method

The invention relates to a DC/DC switching power supply input active differential mode filtering device and a filtering method, belongs to the technical field of filters, and solves the problems that an existing filter has limitation on differential mode interference with a large interference current value and is large in size and weight. The filtering device comprises an input power supply and a power loop used for filtering and controlling differential mode interference current, and the power loop comprises a DC/DC switching power supply and a filter circuit; the DC/DC switching power supply forms the differential mode interference current in the power loop when a switching tube of the DC/DC switching power supply is switched off; and the filter circuit is connected in series with the DC/DC switching power supply and is used for filtering the differential mode interference current, and the power supply input current keeps an approximate constant value by controlling the conduction impedance of a power trans