Clean Sky is the most ambitious aeronautical research program ever launched in Europe. Its mission is to develop breakthrough technologies to significantly increase the environmental performances of airplanes and air transport, resulting in less noisy and more fuel efficient aircraft, hence bringing a key contribution in achieving the Single European Sky environmental objectives.

Since the number of variable speed electrical motors in aircrafts increases and therefor the total installed electrical power continuously rises the power density of a power core becomes more and more of big importance since the weight is directly coupled with the energy consumption. A low weight-to-power-ratio therefore leads to savings of fossil fuels or respectively to an increased range or payload.

One reason for the heavy weight is the passive filter to suppress the electromagnetic interference (EMI). The common-mode voltage (CMV) can be called as one of the main reasons for EMI. With increased switching frequency the CMV filter can be designed smaller but this approach leads to higher switching losses and requires therefore a larger heatsink.