Optimisation of ZVS-controlled Inverter Range for Light Load Section of N-phase Interleaved Parallel Three-level Bidirectional Buck/Boost Converter

When the N-phase interleaved parallel three-level bidirectional buck/boost converter is controlled by triangular current mode (TCM) to achieve zero-voltage switching (ZVS) in the full power section, there are problems that the switching frequency range is too wide and the frequency of the light load section is too high. In this paper, the working principle of the converter is first analyzed, the ripple characteristics of the inductor current are obtained, and the general expressions for the peak value of the inductor current are derived for various conduction modes and the number of bridge arms. A combined frequency conversion control strategy with variable conduction mode and the number of bridge arms is proposed to realize the TCM control of inductor current reversal, and the ZVS switching frequency of the converter under light load condition is limited to the allowable range by changing the conduction mode of the switch tube and the number of bridge arms working on the converter. According to the data sheet of each component, the loss model of the converter is established, and the efficiency of the combined frequency conversion control strategy proposed in this paper is verified by using the model. Finally, the pro-posed control strategy is effectively verified by simscape electrical simulation experiments.