Small-signal Analysis of Novel Bidirectional Naturally Clamped Zero Current Switching Current-fed Half-bridge DC/DC Converter for Hybrid Energy System

Abstract

This article presents the small-signal analysis and controller design of a novel current-fed bidirectional DC/DC converter for a hybrid energy system. The converter achieves soft switching of all active switches at both sides. The switching sequence of the secondary side active switches naturally clamps the voltage across the primary switches. Thus, no additional clamping circuit is needed. Hence, this converter has high power density, high efficiency, and low device requirements. The dynamic analysis and small-signal modeling is carried out using a state-space averaging technique. The model takes into account the currents through inductances in each transition interval to accurately predict the dynamic behavior of the converter. The design of controller using two-loop average current control is illustrated. Bode plots using MATLAB (The MathWorks, Natick, Massachusetts, USA) are plotted to verify the stability of the complete system and the simulation results obtained using PSIM 9.0 (Powersim Inc., Rockville, Maryland, USA) are presented to verify the controller design and converter's transient performance with a step change in load. The simulation and experimental results show that the small-signal model has good controllability and anti-disturbance resistance.