A Novel Method of Suppressing the Inrush Current of Transformers Using a Series-Connected Voltage-Source PWM Converter

This paper proposes a novel method of suppressing the inrush current of transformers. A small-rated voltage-source PWM converter is connected in series to a transformer through a matching transformer. Since the connected PWM converter serves as a resistor for the source current, no inrush phenomenon occurs. The basic principle of the proposed method is discussed. Digital computer simulation is implemented to confirm the validity and excellent practicability of the proposed method using PSCAD/EMTDC. A prototype experimental model is constructed and tested. The experimental results demonstrate that the proposed method can perfectly suppress the inrush phenomena. The required-rating of the PWM converter, which acts as a damping resistor for the inrush phenomena, is about 0.25% of that of the main transformer in single-phase circuits, in the experimental results. In three-phase circuits, it is less than 0.1%.