Three-Leve l Inverter-Based Shunt Active Power Filter in Three-Phase Three-Wi re and Four-Wire Systems

Three-Leve l Inverter-Based Shunt Active Power Filter in Three-Phase Three-Wi re and Four-Wire Systems

presents a direct current-space-vector control of an active power filter (APF) based on a three-level neutral-point-clamped (NPC) voltage-source inverter. The pro- posed method indirectly generates the compensation current ref- erence by using an equivalent conductance of the fundamental component using APF’s dc-link voltage control. The proposed con- trol can selectively choose harmonic current components by real- time fast Fourier transform to generate the compensation current. The compensation current is represented in a rotating coordinate system with chosen switching states from a switching table imple- mented in a field-programmable gate array. In addition, a three- 1phase four-wire APF based on a three-level neutral-point-clamped inverter is also presented. The proposed APF eliminates harmon- ics in all three phases as well as the neutral current. A three-phase three-wire NPC inverter system can be used as a three-phase four- wire system since the split dc capacitors provide a neutral connec- tion. To regulate and balance the split dc-capacitor voltages, a new control method using a sign cubical hysteresis controller is pro- posed. The characteristics of the APF system with an LCL -ripplefilter are investigated and compared with traditional current con- trol strategies to evaluate the inherent advantages. The simulation and experimental results validated the feasibility of the proposed APF.