Passive common mode filter and method for operating a passive common mode filter

摘要

An electromagnetic interference filter for filtering common mode current in an inverter device, the filter comprising: an inductor coupled in a least one power supply line to the inverter device; the inverter device having a ground return line, a capacitor coupled between the inductor and the ground return line; and a controlled switch coupled in series with the capacitor between the inductor and ground return line, and a control unit controlled in accordance with commutations in said inverter device whereby said switch is turned on when common mode current is drawn by said inverter device and turned off when common mode current ceases substantially to be drawn by said inverter device.