Modeling and analysis of N-port DC-DC converters using the cyclic average current

Multi-port DC-DC converters are very attractive because they have the potential to combine different energy sources and management strategies. Their utilization is not only reducing the cost and size of the conventional energy sources but also facilitating the entrance of alternative energy sources on the market. In this paper, the modeling and analysis of such power electronic devices with N ports are discussed. A new representation of the average current flowing in and out of the terminals of an N-port converter is presented. This new average current, named as the cyclic average current (CAC), has shown advantages for the modeling, optimization, and control of the N-port converter. The large-signal model (LSM) and small-signal state-space model (SSM) of an N-port converter are derived using CAC and compared to the LSM and SSM derived using the average current (OAC) in the literature. The modeling procedure is demonstrated for a 5-port DC-DC converter. Simulation is then used to compare the LSM and SSM models and observe their performance with respect to a detailed model (DM).