After enhancing Takagi-Sugeno (T-S) fuzzy methods, we propose an observer-based integral fuzzy controller to deal with the output regulation for
DC-isolated flyback converters without current sensors. The integral control has a great advantage for maintaining zero steady-state error in constant disturbances. This is especially suitable for the converter
systems, where the output voltage regulated at a desired value is emphasized. The controller is inferred from the constraint of the virtual-desired variables (VDVs), which includes a control law with parallel distributed compensation (PDC) style and a specific compensator. Based on the membership functions satisfying a Lipschitz-like property, the
controller gains and observer gains can be designed separately and obtained by solving linear matrix inequalities (LMIs). The overall closed-loop system with quadratic stability is very robust to uncertainty and has powerful ability for error convergence. The sensorless controller is realized by digital signal processors (DSPs). The simulations and experimental results verify the feasibility of the novel scheme and show the satisfactory performance.