Abstract: The DC/DC converter in the new energy medium voltage DC collection system needs to have a large capacity, while it is difficult to make the capacity of high-frequency DC/DC converter larger, hence it needs multiple modules to be connected in parallel, which consequently leads to higher costs. In addition, the port voltage of photovoltaic power generation has high volatility, which usually requires two levels of converters to be cascaded, resulting in lower system efficiency. For the above reasons, the paper investigates a large-capacity wide-range input DC/DC converter suitable for new energy medium-voltage DC collection. The proposed high and medium-frequency mixing modulation method makes the current waveform approximate to an intermittent trapezoidal waveform, which can significantly reduce the current stress of the switching device, and also enables the transformer work at a medium frequency of 500 Hz, which makes it easier to design and fabricate a larger capacity. In addition, the input voltage range of the converter can be nearly doubled. Therefore, large PV plants can be directly connected to the PV array, using only one converter to realize the MPPT and step-up functions, resulting in a lower system loss. The paper analyzes the working principle of the converter, discusses the parameter design, carries out simulation verification by PLECS simulation software, and builds a 300~500 V/±3 000 V, rated power 7.2 kW principle prototype for experimental verification.