The Influence of the Output Current Deforming Regime on the Input Current Harmonics for a Three-Phase Rectifier Bridge


The present paper was created based on the desire of the author to realize a systemic approach of static converters in general and especially of rectifiers. Looked as system from energetic point of view, a rectifier could be represented “as a black box” without internal energetic sources. It is connected to external environment with an electric DC load and a power supply (mono-phase or three-phase). On the other side the electric current represents an ordered movement of electric charge carriers. In order to supply a certain current to the DC load, the electrons must be “transferred” by the static converter from power supply. Thus, a certain wave form of the current at the output can be obtained only based on some wave forms of the currents from the supply phases. The present paper answers to two questions: (1): does the modification of the spectrum of the load current produces the modification of the spectrum of the currents from the supply phases; (2):if yes, how it modifies the spectrum of the current from the supply phase, only in the magnitude of the basic harmonics, or it appears new harmonics? The paper proves the fact that the spectrum of the currents from the supply phases of the three-phased bridge rectifier depends on the harmonic spectrum of the output current. This dependence is materialized only on the change of the components of basic harmonic spectrum, without some visible new harmonics. images