Abstract：In this paper, a zero voltage switching (ZVS) N-type interleaved three-level bidirectional DC-DC converter is proposed in order to overcome several critical issues, such as high voltage stress on the switches, large current ripples in the input current, output current and inductor current, which are associated with two-level DC-DC converters. The proposed converter adopts a paralleled two-phase interleaving three-level structure and its switches are turned on with a phase-shifting angle 90°, which reduces the input and output current ripples as well as the voltage stresses on the switches. A soft-switching control algorithm based on frequency adjustment is employed which enables the converter to achieve ZVS of all switches within a wide load range. Consequently, the efficiency of the converter can be improved. The operation principles and mathematical model of the converter have been analyzed in detail and the relations among the inductor current ripple, the input current and the duty cycle have been deduced. Meanwhile, the relations among the minimum negative inductor current, the average inductor current and the switching frequency have also been derived under the ZVS condition. Finally, a 50V/200V 650W prototype has been built and the theoretical analysis results are verified by the experiments. The ZVS operation is realized for all the power devices, the input current ripple of the converter is almost zero and an efficiency of 96.85% is achieved.
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2020, Vol. 35 
