Method for controlling minimum starting current of internal high-frequency chain power electronic transformer

The invention discloses a minimum starting current control method for an internal high-frequency chain power electronic transformer. A topological structure of the EPT comprises an input-stage PWM rectifier, an intermediate-stage internal high-frequency DC-DC converter and an output-stage voltage source inverter. The input-stage PWM rectifier and the intermediate-stage DC-DC converter are combined, the DC-DC converter is started to work in the rising process of the output direct-current bus voltage of the input-stage PWM rectifier, the output-stage DC-AC inverter starts an inversion program under the condition that the minimum inversion direct-current bus starting voltage is met, multi-stage cooperative simultaneous control is formed, and the output direct-current bus starting voltage of the output-stage DC-AC inverter is increased. The purpose is to reduce the difference between the input side DC bus voltage and the output side DC bus voltage of the internal high-frequency DC-DC converter and achieve the pur