Transient thermal network model for train‐induced wind cooling dry‐type on‐board traction transformer in electric multiple units

Abstract Thermal characteristic is one of the key performances of dry‐type on‐board traction transformer (D‐OBTT), which directly affects the operation safety of the new generation electric multiple units. However, due to the particularity of train‐induced wind cooling mode of D‐OBTT, the existing efficient thermal modelling methods cannot be used under fluctuating air velocity and load. A time‐saving transient thermal model for D‐OBTT is proposed. First, the framework of the transient thermal network model (TTNM) is proposed considering the coexistence of non‐fully and fully developed state of the train‐induced wind and the addition heat flow in the solid domain. Then, a novel formula for calculating the length of non‐fully developed section considering the geometric dimensions and heat flux density is proposed based on computational fluid dynamics (CFD) parametric sweeps for the first time. The accuracy of TTNM is validated by a D‐OBTT experimental setup, and the time consumption is significantly reduced compared with CFD.