The 3-level circuit of GRIDCON® ACF is based on twelve IGBTs, whereas conventional 2-level active filters only comprise of six. The special circuitry halves the voltage load of the power semiconductors. On the one hand this results in lower losses and on the other hand enables use in grids with a higher rated voltage. The DC link voltage is also higher which allows higher peak currents to be generated, which
is essential for filtering harmonics with a high bandwidth. Another benefit of the 3-level technology is the lower ripple of the output current compared with the 2-level architecture. The split DC link and the larger number of IGBTs result in an additional third inverter state at the output. This can be used to make the line filter and EMC filter more compact with the same switching frequency and thereby reduce losses.