Multi-Level Active Filter for Medium Voltage Applications

This paper investigates the application of a multi-level active filter based on cascaded H-bridge inverters for use in medium voltage systems. Low switching frequency of the devices and a small magnetic content are proposed to meet the requirements for harmonic compensation. Device loss calculations are presented to show that IGBTs can be utilized without any derating with the proposed switching frequency. Steady state, transient and start-up operation are shown using simulations. The combination of high device utilization and low inductive filter rating results in a medium voltage solution that can be cost competitive with conventional low voltage active filters at high power levels.