Robust digital controller for fourth order converter

In this paper a digital voltage-mode controller is proposed for the fourth order split inductor converter (FOSIC) that gives robust performance. Firstly, the salient features of the proposed topology are compared with the conventional SEPIC converter. Discrete-time mathematical models are formulated and then compensator is designed using direct digital design approach. A compensator with complex-conjugate poles is designed to minimize the effect of right half plane (RHP) zeros of the converter. This feature allows increasing the crossover frequency as well as the dynamic response time. Compensator design is validated through simulations and then experimental measurements. Load voltage regulation, disturbance rejection capabilities of the closed-loop converter system are also simulated and then verified through experimental measurements.