Harmonic suppression method and apparatus for three-phase three-wire cascaded power conversion apparatus

Abstract

A harmonic suppression method and apparatus for a three-phase three-wire cascaded power conversion apparatus is disclosed. The method can include: calculating a first current output from a full-bridge rectifier module to a floating direct current side, the first current being composed of a first current direct current component and a first current double frequency component; and generating a first injection voltage with a triple frequency, so as to inject the first injection voltage into the floating direct current side and transfer at least a portion of the first current double frequency component to a low-voltage direct current side, where total current on the floating direct current side is composed of the first current and a second current after the first injection voltage is injected, the second current is composed of a second current double frequency component and a second current quadruple frequency component, and the amplitude and the phase angle of the first injection voltage are configured so that the first and second current double frequency components are at least partially canceled. The method reduces the demand for capacitance on the floating direct current side of the power conversion apparatus, resulting in a significant increase in power density and high power conversion efficiency.