Benefits of saturated powder core inductors in LCL filters of three-phase voltage source inverters

Magnetic powder cores introduce a varying inductance to LCL filters of voltage source inverters due to their saturation characteristics. This has a great impact on the inverter output current ripple. We propose a filter and inductor design method which considers the saturation effects. The advantages of saturating filter inductors in terms of the required inductance, inductor volume, core losses and winding resistance are derived analytically. Allowing inductor saturation during fundamental current amplitude results in a drastic volume and winding resistance decrease. Experiments verify the expected current ripple and winding resistances depending on the desired inductor saturation. The topic is discussed by means of a 10 kW three-phase voltage-source inverter.