Featured properties of PV array – dual active bridge system for efficient MPPT implementation

This paper investigates the potential of using the Isolated Dual Active Bridge (IDAB) converter for Maximum Power extraction from PV arrays integrable with multilevel grid-tied inverters. The investigation is based on analytical derivations using multifrequency averaging approach and piecewise linearization. The developed new six order model is simplified to the third order model via steady state and stability analyses. It gives explicit steady state solution revealing necessary features for the efficient Maximum Power Point Tracking (MPPT) algorithm design and implementation, including relationship between PV voltage and IDAB phase shift ratio (PSR), and the influence of the IDAB switching frequency on this relationship. It is shown that the imposed control restrictions provide the unique mapping between the PV voltage and IDAB PSR. The dynamical model is used for the estimation of the MPPT sampling time and assessing the influence of the systems parameters on dynamical properties. The stability analysis of the initial model shows that the system is always stable for realistic parameters values and the number of oscillations can be reduced via increasing the PV output capacitance. The derived model can be used as sufficient tool for optimization of MPPT time sampling and PSR step.