PI control system for input current of active rectifier in SST

Abstract

Recently, Solid State Transformer (SST) is proposed to switch the conventional distribution transformers since it has potential to reduce the volume and weight. Three stages SST is the combination of a rectifier, a DC-DC converter and an inverter. Since these three power electronics are connected together, the power output of rectifier will become the input power of DC-DC converter and the output power of DC-DC converter will become the input power for inverter. However, since the active rectifier is a part of SST and also a non-linear load, it causes the input current to become distorted and it will affect the power factor of the active rectifier. That is why, a new control system consists of phase locked loop, voltage loop control and current loop control needs to be designed. However, this study only focus on the designing of current loop control and voltage loop control by using PI control system in order to control the input current of the active rectifier that will produce the output voltage near the reference value. By providing better input current also, the power factor of the active rectifier also can be improved. Hence, unity power factor can be achieved and the efficiency of the active rectifier becomes better.