Power electronic systems usually produce high amounts of electromagnetic interferences (EMI)due to PWM operation. To comply with international standards on electromagnetic compatibility(EMC), e. g. EN 61800-3 in industrial applications [1], the EMI shall not exceed given limits. Toreach these limits often filters need to be integrated into the system. The common solution is toadd passive EMI filters consisting of capacitors and inductors [2]. Passive filters are often bulkyand heavy, therefore active cancellation techniques for power electronic systems were introduced[3]. Active EMI filter (AEF) consists of an analog (and rarely also digital) circuit to actively suppressthe disturbances by injecting an anti-noise signal.As discussed in [4], well-known closed loop feedforward or feedback structures for AEF have theirlimitation specially because of the limited amplifiers open-loop gain, delays due to the finite signalpropagation speed in the circuit and the measurement accuracy. For this reason, active EMIcancellation by injecting synthesized signals was introduced.This paper introduces a method for generating a synthesized signal for a three-phase gridconverter.