Fast Response Nonlinear Injection Control of Isolated DC-DC Converter for Cable-based Seabed Observatory Platform

The paper presents the design of a controller for a current-fed isolated step-down DC-DC converter, which serves as the power supply for cable-based seabed sensors. The controller includes nonlinear compensation of unknown load, as previously proposed, and additional proportional-integral feedback that enhances the fast response as 10 times the natural response while maintaining the system’s stability, even with several converters put in a series. The system’s output voltage is controllable, even when the output current is null. The analyses of zero and poles are shown, and the method to calculate the gain coefficients of the controller is also presented. The new coefficient $\zeta$ is easily conceivable and is introduced as a calculation parameter. Simulation using Matlab - Simulink - Simscape confirms the results obtained.