Small-Signal Analysis of Naturally Commutated Current-Fed Dual Active Bridge Converter and Control Implementation Using Cypress PSoC

A detailed small-signal analysis and a closed-loop control design of a naturally commutated bidirectional current-fed dual active bridge (CFDAB) dc/dc converter are presented. The proposed converter is suitable for a fuel cell vehicle (FCV) between a traction inverter and batteries. State-space averaging technique is used to derive the small-signal model. Based on the derived small-signal model, a closed two-loop controller is designed and implemented on mixed signal (analog and digital) processor Cypress programmable system-on-chip (PSoC) 5. A complete design procedure is presented. Simulation results using PSIM 9.0.4 and experimental waveforms from a 250-W prototype with the designed controller are shown to verify the stability of the control system. Experimental results for step changes in load clearly show satisfactory transient performance of the converter and validate the closed two-loop design. It is suitable for energy storage, interfacing two dc buses of different voltages in a microgrid and a solar photovoltaic power system to boost a low-voltage panel up to the peak of the utility voltage.