Analysis of a Five-Port Differential Power Processing Triple Active Bridge Converter for Active Cell Balancing in Lithium-ion Battery Packs

This paper proposes a novel five-port differential power processing triple active bridge (DTAB) converter that provides active and hybrid cell balancing for lithium-ion battery packs. The proposed DTAB converter significantly reduces the modular active battery balancing system cost by reducing component count per active balancing output. Five ports are supported from one triple active bridge using center-tapped transformers with interleaving inductors. Active balancing is achieved by controlling the differential current injected into the mid-point of the cell sub-modules using pulse-width modulation. Traditional phase-shift modulation is used to regulate the power of the load bus. Converter operation, a decoupled steady-state analysis approach, and details of the proposed modulation scheme are provided. Simulation results for one five-port DTAB converter operated at 200 kHz that provides up to 350 W to a shared 15 V load bus using 4 series-connected 25 Ah NMC battery cells with mismatched cell voltages validate the converter operation.