Multi-variable Control-based Conduction Loss Optimization in Dual Active Bridge Converter Considering Generalized Harmonic Approximation Oriented Steady-State Model

This paper demonstrates a novel frequency domain general harmonic approximation (GHA) based steady state modeling technique of the dual active bridge (DAB) converter. This proposed model is employed to simplify the mathematical formulation of the instantaneous as well as RMS currents of the converter, critically accountable for the system switching and conduction losses. Also, all the possible phase shift control methods, including single, dual, and triple phase shift modulations are rigorously studied and investigated in order to provide a generic and detailed insight on the applicability and benefits of using them on a wide range of gain and load demand while ensuring minimized conduction losses. A 400W proof-of-concept of DAB DC-DC converter has been developed to validate and establish the proposed frequency domain model-based theoretical analysis and claims. While the converter has a fixed input DC bus voltage of 160V, the output load power is varied within a range of 50W to 400W with a large swing in output voltage level, i.e., from 90V to 150V. With the implementation of the proposed optimal triple phase shift (TPS) control at extreme gain conditions, the experimental results show a system efficiency increment of 3.5% and 2.2 % compared to the conventional single-phase shift (SPS) modulation technique at 90V, 50W and 150V, 200W outputs, respectively.