Development of Power Electronic Distribution Transformer Based on Adaptive PI Controller.

In recent years, power electronic distribution transformers (PEDTs) have become an attractive replacement for conventional transformers. This is due to their smaller size, improved dynamic performance, and better power quality. However, their operation with a conventional controller such as a proportional integral (PI) does not give satisfactory performance. Thus, improved dynamic performance and high power quality of the PEDT can be achieved with an intelligent control. In this paper, a novel design topology and an improved controller for a PEDT are proposed. The proposed controller is based on the adaptive PI-fuzzy logic controller (API-FLC). The FLC is applied to adapt the PI controller gains when there is a sudden change in the system parameters. The PEDT with the novel controller is designed to achieve constant dc link voltages, sinusoidal voltage, and current with unity power factor under different operating conditions. The model is simulated and validated using MATLAB/Simulink software. Different operating conditions, including voltage sag, voltage harmonics, sudden load change, and short circuit, have been investigated. The results obtained with the API-FLC controller give a better dynamic performance and improved power quality when compared to the conventional PI controller. Therefore, the PEDT based on API-FLC has the advantages of eliminating transient power quality problems and improving system efficiency.