Abstract: The application of DC transmission and distribution network faces a variety of complex design

scenarios，among which there are DC/DC conversion requirements with unipolar input and really bipolar output. The bipolar output of this application scenario can easily lead to unbalanced output voltage when the load is unbalanced，which can affect the stable operation of the system. In response to the above problems，a DC transformer and power balance topology for unipolar to really bipolar conversion were proposed，which could solve the problem of DC/DC voltage conversion in the case of unbalanced load. A power balance system（PBS）was designed between the output positive and negative poles，so that unbalanced powerwas transmitted through the systemto balance the voltage between the two poles.Finally，simulation results and experimental results verify the feasibility of the proposed topology.

      Key words: DC transformer；unipolar；really bipolar；power balance system（PBS）