The main purpose of traction converter is to convert DC voltage obtained from new energy into three-phase voltage with variable frequency and voltage transformation, which is used to control the traction motor to drive the vehicle to run in traction, inertia and braking conditions. The IGBT semiconductor devices of the traction converter are effectively cooled by circulating water cooling, and the structure of the inverter is very compact. Through internal and external cooling cycles, the heat of the inverter is effectively transferred out to prevent overheating. Small size, high energy.