Equivalent impedance characteristic analysis for the three-phase diode-bridge rectifier with dc capacitance

A new harmonic matrix model for three-phase diode-bridge rectifier is proposed in the paper. The relationships between rectifier supply harmonic voltages and its generated harmonic currents can be directly illustrated through the matrix model. Therefore, the model is very suitable to analyze the equivalent harmonic impedance characteristic of the rectifier. Based on the derived equivalent circuits, the mechanism for impedance characteristic of the rectifier is analyzed under two different voltage conditions. Calculation and simulation studies for the circuit are performed and the results show that under different voltage or load parameter conditions, the circuit could appear to be capacitive or inductive. Furthermore, the range of load parameter R corresponding to a capacitive equivalent circuit under certain voltage conditions is obtained through mathematical calculation and analysis. The results of the paper can be used to evaluate the potential resonance condition for systems containing three-phase diode-bridge rectifiers with dc filtering circuit.