Comprehensive PowerLoss Analysis and Optimizing of FB PFC DAB DC/DC Battery Charger in Sinusoidal Charging

One of the most important restrictions of the double stage battery chargers is the capacity and size of the DC-link capacitors. In single-phase battery chargers, the input power is oscillating with double line frequency while the battery charged/discharged with DC power. The difference between these powers mostly stored in the DC-link. As a result, although the size of the passive component can be reduced by increasing switching frequency, the DC-link capacity is independent of the switching frequency. Sinusoidal charging is an innovative charging algorithm that leads to lower DC-link capacity and hence the charger requires less space. However, the effect of this charging method on the performance of the charger has not been investigated before. In this paper, a comprehensive power analysis of a FB PFC DAB DC/DC battery charger is performed. The results obtained from powerloss analysis show that sinusoidal charging reduces the efficiency of the system and also limits the range of the output power which further leads to lower efficiency. As the most of the powerloss related to the second stage, an optimizing TPS switching algorithm is selected to control the DAB DC/DC converter. Results show that the selected switching method well reduces the powerloss of the second stage and thereby the efficiency is increased.