Abstract: High voltage converter is often used in high voltage direct current（HVDC）transmission system to

control power supply nearby at high potential. However，the high bus voltage and its wide range fluctuation in the

module pose a challenge to the high reliability design of power supply. To solve this problem，a high voltage module power supply system was proposed based on the series dual-tube flyback topology. The multi-input and single-output DC transformer was used as the transformer carrier of the system. Using the self balancing characteristics of all levels of connected units under the synchronous control signal，the dynamic self balancing control of each series circuit was realized，and the voltage stress of semiconductor switches in each module was actively reduced. In addition，this method has the advantages of high leakage inductance energy feedback efficiency and clamping the maximum voltage stress of the switch to the input voltage. Finally，with the help of system simulation and hardware in the loop simulation platform，the feasibility of the proposed self powered circuit system and the correctness of theoretical analysis were verified.

      Key words: high voltage power supply circuit；dual-tube flyback topology；active voltage balance