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A Lightweight Optimization Study for Large Capacity Dry-Type On-board Traction Transformer of EMU Based on CFD and RSM | IEEE Journals & Magazine | IEEE Xplore

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 (OBTT) cooled by train-induced wind is an effective way to realize the lightweight of on-board equipment. However, the ex...Show More

Abstract:

Using the dry-type on-board traction transformer (OBTT) 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 OBTT (D-OBTT) cannot meet the power requirements of the high-speed electric multiple units. For the large capacity D-OBTT, the lack of mathematical models that can reflect the relationship between hotspot temperature and design parameters limits its development. This article aims to propose an optimization method for large capacity D-OBTT. First, the user-defined function-based computational fluid dynamics modeling method for D-OBTT is proposed and validated to accurately obtain the winding hotspot temperature. Then, the response surface models of winding hotspot temperature are first proposed based on the response surface methodology. Finally, the lightweight optimization of a 6.3-MVA D-OBTT is completed, and the influence of design parameters on weight reduction is studied. Under the conservative optimization strategy, the total weight of D-OBTT is reduced to 3650.40 kg, which is reduced by 38.55% compared with the oil-cooled OBTT with the same rated capacity. This article provides an efficient and feasible method, and regular guidance for the lightweight optimal design of D-OBTT, and the obtained response surface models can be used for the optimization of similar D-OBTT under different specific needs.
Published in: IEEE Transactions on Transportation Electrification ( Volume: 9, Issue: 2, June 2023)
Page(s): 2941 - 2954
Date of Publication: 24 November 2022

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I. Introduction

Reducing the weight of on-board equipment is the development trend of higher performance electric multiple units (EMUs) because the weight directly affects the energy consumption and the wear between wheel and rail, and this effect is more significant at the higher running speed [1]. The on-board traction transformer (OBTT) is the key equipment of the traction system of EMUs, which is used to provide traction power and provide power supply for auxiliary equipment. The weight of the existing oil-cooled OBTT accounts for about 15% of the weight of a single carriage [2], [3], [4], which is the heaviest electrical equipment in the EMU. This inherent disadvantage limits the development of EMUs toward higher speed, higher efficiency, and better performance. Dry-type OBTT (D-OBTT) is considered as a lightweight substitute for oil-immersed OBTT because it does not contain heavy components, such as cooling oil, tanks, conservators, and oil coolers, and is directly cooled by the airflow (train-induced wind) generated during train operation. At present, Hitachi Energy Ltd. has launched an 800-kVA small capacity fan-cooled D-OBTT that can be used for low-speed level intercity EMUs [5], [6]. However, the large capacity D-OBTT for high-speed EMUs using train-induced wind cooling is still blank.

References

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