Digital implementation of harmonics reduction of three-phase boost rectifier

Abstract

The line currents of three-phase diode bridge rectifier suffer from high THD. This THD is higher than IEEE standards. Injection of six harmonic components to the control signal of the boost converter connected to the three-phase diode bridge rectifier reduces the THD of the utility line current. In this paper a digital implementation of injecting six harmonic to the control signal of three-phase boost rectifier is shown. The digital implementation is carried out by using FPGA. In this study a sin-wave and a triangle-wave with six times the fundamental frequency and variable amplitude are digitally generated in the FPGA. Each signal is added to the dc control signal component of boost converter to be compared with digitally generated saw-tooth. The simulation and experimental results show that the THD of the utility line currents depends on the amplitude and phase-shift of the six-order component injected to the control signal of the boost converter and the angle of input three-phase voltage.