Graph Theory-Based Sneak Circuit Analysis and Trigger of Semi-DAB With Parasitic Parameters

Parasitic parameters and dynamic sneak paths would lead to unexpected phenomena, exerting negative impacts on the reliability and safety of semi-dual active bridge (S-DAB) dc–dc converter. Therefore, a graph theory-based sneak circuit characteristics analysis, trigger mechanism, and suppression method of S-DAB are proposed in this article. The complete current-based sneak path modeling is obtained, combining both bridges via high-frequency-link inductor current. Then, the accurate sneak modalities are proposed and detailed, including high-order and first-order sneak operating modalities. Thus, the possible sneak circuit phenomena are detailed to explain the negative impact on operating characteristics, depicting the chaotic phenomenon caused by the dynamic characteristics of bus capacitance. Then, the trigger mechanism and timing are proposed and indicated in time series. Moreover, the suppression conditions are derived by optimizing modulation parameters and parasitic parameters. Compared with the previous research articles, the modeling, analysis, and suppression of sneak operation are more detailed and general in this article to improve the stability and reliability of S-DAB. Finally, the experimental results verify the theoretical analysis. The variation range of converter output with proposed suppression method is reduced by 65.4%, and the bifurcation chaos can be suppressed effectively.