A hybrid resonant three-level converter based on dual transformers is proposed

which is suitable for the access of distributed photovoltaic power to the medium voltage DC distribution network. The proposed converter can be obtained by adding an auxiliary circuit into the traditional neutral point clamped three-level circuit

achieving the basic three-level circuit operation with fixed duty cycle. The converter operates in a discontinuous current mode. The basic three-level circuit transits most of the power

and zero-current switching for the basic three-level circuit is realized in the full load range by pulse width modulation of the auxiliary circuit. As a result

the switching loss of the converter can be significantly reduced. This paper also discusses the effects of the ratio of auxiliary transformer and the resonant capacitance on the switch current

the peak value of resonant voltage and the value of resonant inductance. Then the parameter design principles are put forward. Finally

a prototype of 300~1 500 V/2 kW is built to verify the performance of the proposed converter.