Insulated gate bipolar transistor（IGBT） is the core component of AC/DC conversion in VSC-HVDC

and its reliability directly determines the stable operation of VSC-HVDC. During the operation of the converter valve

various faults cause the IGBT module current to rise sharply

and the rising current can arouse temperature rise of IGBT module and cause certain damage to the solder layer

and long-term damage eventually leads to fatigue failure of the solder layer. Therefore

the IGBT module for VSC-HVDC converter valve is taken as the research object to conduct the electromagnetic-thermal-mechanical stress coupling analysis under the power cycle condition. Subsequently

by using Coffin-Manson formula of strain-based fatigue life model

the life expectancy of the solder layer is predicted under the condition of the inelastic strain increment generated by a single power cycle of the solder layer. Finally

a 10 kW/1 000 A power cycle test platform was designed to verify the electrical characteristics

thermal characteristics and fatigue life of the solder layer obtained by simulation analysis. The results show that the temperature distribution of the upper solder layer is related to the bonding points and the bonding wires distribution

and the temperature distribution of the lower solder layer is related to the chip position distribution. The thermal stress caused by uneven temperature distribution of the solder layer and large temperature difference are the main causes of the solder layer fatigue failure

and the fatigue life of the upper solder layer is less than that of the lower solder layer.