Extended Describing Function Method Based Modeling Technique for Three-Port Series Resonant Converters

Nowadays, with the development of the consciousness of environment protection and the renewable energy utilization technologies, existing power system is pushed towards containing renewable energy sources while supporting more varied power loads at the same time, for which multiport dc-dc resonant converters shows distinct advantages in interacting with multiport energy terminals with higher power density, higher efficiency and less device cost. Since the introduction of resonant tanks helps to improve the efficiency and symmetry of a multiport converter, it also raises the complexity of the whole system. This paper studies the method for estimating the steady-state operation points of a three-port converter with three series resonant tanks (3pSRC) which is based on the extended describing function method. Meanwhile the phase-shift characteristics of the studied converter are also analyzed. The proposed model is convenient to calculate in controlling and shows high accuracy in predicting dc-link voltages and power flows at each port.