Three-phase infinite level inverter based active power filter

Abstract

Traditional 2-level voltage source inverter (VSI) based active power filters (APF) has a high DC voltage across the capacitor. A pure APF connected to a 3-ϕ 400V line voltage, will have a DC voltage of more than 600V for its effective working. Active switches in the inverter subjected to this voltage, results in a high voltage stress. Multi-level inverter topology in APF reduces the voltage stress and harmonic content to a greater extend but the tradeoff is more number of active & passive devices and complex control circuitry. A new type of VSI topology called 3-ϕ infinite level inverter based active power filter is proposed to mitigate the above problems to a larger extent. This topology has many number of voltage levels depending on the carrier frequency with same number of components. DC-link voltage is reduced due to low harmonic content and high utilization of DC voltage. Thus the voltage across the capacitor & active switches are low and thereby the voltage stress is considerably reduced. Instantaneous reactive power theory control technique (IRPT) or PQ Theory is used for fundamental reactive power compensation and harmonic filtering. Computer simulation using MATLAB/Simulink is presented to verify the above results. Experimental waveform obtained with the generation of voltage waveforms from the infinite level inverter is shown.