In this paper, the four leg inverter controlled by the three dimensional
space vector modulation (3D SVM) is used as the shunt active power filter
(SAPF) for compensating the three phase four wire electrical network, by
using the four leg inverter with 3D SVM advantages to eliminated zero
sequence current, fixed switching frequency of inverter switches, and reduced
switching losses. This four leg inverter is employed as shunt active power
filter to minimizing harmonic currents, reducing magnitude of neutral wire
current, eliminating zero sequence current caused by nonlinear single phase
loads and compensating reactive power, and a nonlinear sliding mode control
technique (SMC) is proposed for harmonic currents and DC bus voltage control
to improve the performances of the three phase four wire four leg shunt
active power filter based on Synchronous Reference Frame (SRF) theory in the
dq0 axes, and to decoupling the four leg SAPF mathematical model.