Active emi filtering using magnetic coupling cancellation

A power converter producing harmonics impressed on a power signal, the power converter comprising an active differential mode filter, the filter comprising:

• a first and second coil wound on a common core, wherein the first coil acts as a passive differential mode filter;
• and
• a current sensor block sensing harmonics as an interference current on the power signal;
• wherein
• the second coil adds a cancellation signal, based on the interference current, back into the power signal to cancel the harmonics from the power supply.

A method for reducing interference harmonics from a power converter, the method comprising:

• passing the power signal through an active differential mode filter, wherein the filter has a first and second coil;
• sensing the interference harmonics with a sensing device;
• and
• canceling the interference harmonics in the power signal by delivering a phase-shifted interference signal to the power signal.