A Lightweight Optimization Study for Large Capacity Dry-Type On-board Traction Transformer of EMU Based on CFD and RSM

Abstract

Using the dry-type on-board traction transformer cooled by train-induced wind is an effective way to realize the lightweight of on-board equipment. However, the existing small capacity fan cooled dry-type on-board traction transformer cannot meet the power requirements of the high-speed electric multiple unit. For the large capacity dry-type on-board traction transformer, the lack of mathematical models that can reflect the relationship between hotspot temperature and design parameters limits its development. This paper aims to propose an optimization method for large capacity dry-type on-board traction transformer. First, the user-defined function based computational fluid dynamics modelling method for dry-type on-board traction transformer is proposed and validated to accurately obtain the winding hotspot temperature. Then, the response surface models of winding hotspot temperature are firstly proposed based on the response surface methodology. Finally, the lightweight optimization of a 6.3 MVA dry-type on-board traction transformer is completed, and the influence of design parameters on the weight reduction is studied. Under the conservative optimization strategy, the total weight of dry-type on-board traction transformer is reduced to 3650.40 kg, which is reduced by 38.55% compared with the oil cooled on-board traction transformer with the same rated capacity. This paper provides an efficient and feasible method and regular guidance for the lightweight optimal design of dry-type on-board traction transformer, and the obtained response surface models can be used for the optimization of similar dry-type on-board traction transformer under different specific needs.