A repetitive learning boost converter control of neutral line active power filter based on FPGA and DSP

During the past decades, three-phase three-wire system plays a very important role in the power electronics research, especially in the PWM studies. However, in the distribution site, there are many three-phase four-wire equipments installed. In these systems, single-phase loads and non-linear three-phase loads can produce unbalanced line currents, generating a current into the neutral line as a consequence. In some cases, these neutral line currents, i.e. their RMS value, can be even higher than the nominal value of the three phase line currents. Related problems can be partially resolved by a three-phase shunt active power filter. But the control method of it is quite complicated. Accordingly, this paper introduces a new principle diagram of the active neutral line filter system. Based on the new diagram, a method of repetitive learning control is achieved by FPGA and DSP. The achievement has the features of robustness, zero steady-state error, fast dynamic response. The results of simulation and experiment provide the verification of these salient features.