J. Wang’s scientific contributions

A GAPF(Generalized Active Power Filter) based on three-level inverter is proposed, which has higher equivalent switching frequency and voltage level, suitable for high power applications. Its topology, operating principle and control method are discussed. Because the selective harmonic elimination technique is poor in real-time performance and neutral-point voltage adjustment, the space vector modulation technique is adopted. In order to precisely balance the DC-side capacitor voltages of three-level inverter, a method is proposed to quantitatively calculate the duty cycle of small vector. Simulative results show that, three-level GAPF can effectively realize the functions of reactive power compensation, harmonics suppression and negative sequence filtering and greatly reduce the capacity of grid-side filtering reactor.