A novel PWM method of three-level rectifiers for controlling input-current harmonics at lower switching frequencies

Abstract

This paper propose a novel "inverse-problems" approach to control a three-level rectifier so that the harmonic standards such as IEC 1000-3-2 class A can be met at lower switching frequencies. A conventional programmed switching method eliminates some designated harmonics of converter voltages. This results in a considerable increase in the amplitude of the residual lower harmonics and requires large input filter inductors to meet the standard. The proposed method does not eliminate the lower harmonics, but controls those amplitudes to meet the standard. As a result, the inductance required for the input filter can decrease to 45-33 % of the conventional method.