Three-Level NPC Inverter Control System of Hybrid Active Power Filter by Modulation Ratios of Switching Functions

For harmonic compensation, a control system of a four-wire three-level NPC inverter employedin a hybrid active power filter (HAPF) based on modulation ratios of switching functions is proposed in thispaper. The inverter and two parallel passive filters (PPFs) tuned in 5th and 7th orders of harmonic currentsform the HAPF. The PPFs are used for compensating of average reactive power of loads and filtering of 5thand 7th orders of harmonic currents to decrease rated power of the inverter. The switching functions of theinverter control system are extracted based on compensation of variable load reactive power and the ordersof harmonic currents with exception of 5th and 7th orders. The averaged model of the inverter is extracted bypossible switching states of the inverter’s IGBTs. The proposed control method is applicable underasymmetrical non-sinusoidal source and non-linear loads conditions .The principles of the presented controlmethod are analyzed in this paper too. The proposed control method was simulated and the simulationresults are provided to validate effectiveness of the proposed control method.

کلیدواژه ها:

Hybrid active power filter ، Multi-level inverter ، active power filter ، averaged model ، parallel passive filter ، switching function