Modeling and Analysis of a DC-DC Bidirectional Converter for Vehicular Applications

The bidirectional DC-DC three level converter (TLC) has been proposed as a viable choice for vehicular applications due to its high efficiency, low ripple harmonics and compact size. In this study we investigate the performance of the TLC when operated in a combination of duty cycles that are not the same (d(1) not equal d(4)). Using the model equations of the converter derived using the switching function approach, the inductor current ripple and output voltage ripple are investigated using the harmonic balance technique. Furthermore, the ripple parameters are derived in terms of relevant voltages and transition between buck and boost mode operation is analyzed. The paper also shows why it is better to control the switches of the three level converter with equal duty cycles.