Bidirectional non-isolated dc-dc converter for low-voltage DC-grid

Abstract

In this paper, a fourth-order non-isolated bidirectional converter is proposed for load power management in low-voltage DC grid. With state-space and discrete-time modeling technique, the proposed bidirectional converter is modeled, and small-signal transfer functions are obtained. A digital compensator is designed using these transfer functions both for the charger and discharging cases. The converter is designed to ensure battery current regulation. To test the robustness relevant control theory, for discrete transfer functions, is applied and also formulated important robustness quantifying sensitivity functions. The robust controller is designed and then evaluated its effectiveness against disturbances. A 30 W 12 to 48 V bidirectional converter system is fabricated to confirm the design and simulations. For system robustness validation the measurement results are included for the range of parameter variation considered during design stage.