A fourth-order bidirectional DC-DC converter for interfacing battery in a solar -photovoltaic-fed low-voltage residential DC nano-grid: Design and analysis

摘要

In this paper, a non-isolated fourth-order bidirectional DC-DC converter (FoBiDC) which exhibits continuous input and output current together with minimum-phase response, both during buck and boost modes, is proposed and analyzed. It is then used to interface a battery in a solar photovoltaic (SPV) fed low-voltage low-power residential DC nano-grid (LVRDNG). The design equations for the converter are derived by performing steady-state and time-domain analysis. The small-signal models are developed and used for designing voltage-mode controller to regulate the DC bus voltage of LVRDNG and perform stability analysis. The small-signal analysis reveals the possibility of right-half plane (RHP) zero and formation of an up-down glitch in the frequency response of converter transfer functions which results in slower dynamic response and increased sub-system interactions. Therefore, an optimized power stage design methodology, using particle swarm optimization (PSO), is adopted for optimal parameter selection with the aim to shift RHP zero to left-half plane (LHP) and to mitigate the effect of up-down glitch. The effect of sub-system interactions, arising due to interfacing of FoBiDC, on other coherently operating converter in the LVRDNG is also analyzed by formulating an integrated small-signal model of LVRDNG. The scaled down laboratory prototype of FoBiDC and LVRDNG is developed to experimentally validate the steady-state and dynamic performance. The theoretical and experimental results are found to be in close correlation with each other.