Online impedance measurement of the batteries and loads connected to a Modular Multi-Active Bridge Converter

Electrical distribution systems comprising different power sources and loads, such as electric vehicles, aircraft electrical distribution systems and residential microgrids, need for new power conversion architectures. Multiport converters are an alternative to conventional multi-converter systems to allow the connection of multiple power sources and loads that may change its power flow direction, allowing hot connection and disconnection. In these applications it may be of interest to measure the impedances connected to the ports, to monitor the system or the power sources, such as to control the state of lithium-ion batteries. This work is focused in the identification of the impedances connected to a multi-port Modular Multi-Active Bridge by using a broadband PRBS perturbation that allows for a quick test susceptible of being implemented online. The simulation results and the measurements on an actual 5-port converter show the feasibility of the proposal as well as the accuracy of the results.