Robust control of parallel buck fed buck converter using hybrid fuzzy PI controller

This paper presents development and control of buck fed buck converter topology for high current application. For high current application like DC welding, single converter structure may cause complete system failure if the semiconductor switch fails. Hence, to improve reliability, parallel DC-DC converter structure is proposed in this paper. This arrangement ensures load sharing between the converters when operated in closed-loop mode. Simulation results obtained from the closed-loop configuration with a conventional controller (PI) show good steady-state response. When an intelligent controller like fuzzy controller is used, the same system exhibits better dynamic response. In this paper, the advantages of both these controllers are utilized by judiciously choosing the appropriate controller action at required time intervals. The required time intervals are decided based on the error between the desired and actual value. In other words, fuzzy controller is initiated during the initial time intervals to get quick dynamic response while PI controller comes into action at a later stage to reduce the steady-state error. Simulation results show significant improvement when this hybrid combination of Fuzzy-PI controller is introduced.