Dynamic Temperature Distribution Modeling Method of Dry-Type On-Board Traction Transformer in EMU

The calculation of the dynamic temperature distribution of on-board traction transformers in high-speed electric multiple unit (EMU) is a key step in the verification of the rationality of the design, the assessment of insulation status, and other thermal related work. However, for dry-type on-board traction transformers (D-OBTTs) that are rapidly developing in the context of on-board equipment lightweight, due to their special cooling mode, existing dynamic thermal modeling methods cannot be directly applied. In this article, a dynamic temperature distribution calculation method applicable to D-OBTT is proposed. First, a dynamic thermal network modeling method for the winding area is presented. Then, a convection heat transfer intensity model applicable to the air duct area was obtained based on the dimensional analysis theory. Furthermore, a lumped parameter thermal-circuit model was constructed to obtain the necessary reference temperature in the dynamic thermal network model. Finally, a thermal test under dynamic traction load was conducted on the experimental setup to validate the proposed model. The experimental results indicate that the model proposed in this article has sufficient accuracy and computational efficiency, thus providing an efficient and reliable dynamic temperature distribution calculation method for the optimal design and lifespan evaluation of D-OBTT.