Magneto-thermal coupling simulation and experimental verification for a three-winding high-frequency transformer

2021 ◽  
pp. 1-17
Author(s):  
Yadi Xu ◽  
Lin Li ◽  
Xuan Yuan
Keyword(s):  
Heat Transfer ◽  
High Frequency ◽  
Hot Spot ◽  
Convective Heat Transfer Coefficient ◽  
Core Material ◽  
Fe Model ◽  
Insulation Material ◽  
Thermal Coupling ◽  
High Frequency Transformer ◽  
Spot Temperature

As a core component of the power electronic transformer (PET) in DC network, the multi-level high-frequency power transformer has received great attention due to the insulation material fatigue problems resulting from the hot-spot temperature rises. To solve this problem, a three-winding high-frequency transformer for 10 kVA PET application is designed and made in the laboratory, and the loss and temperature rise distribution is calculated by means of the finite element (FE) electromagnetic-thermal coupling simulation. The influence of temperature on the hysteresis and loss properties of core material has been carefully considered and measured. The influence of skin effect and end effect on the winding loss is taken into account through the establishing three-dimensional FE model. Besides, the convective heat transfer coefficient is solved based on the principle of heat transfer instead of the empirical coefficient method. By compared with the experimental results, the calculated results are validated to be effective in predicting the loss and hot-spot temperature rises of the transformer.

Constructal Placement of Discrete Heat Sources With Different Lengths in Vertical Ducts Under Natural and Mixed Convection

2018 ◽  
Vol 140 (12) ◽  
Author(s):  
Bugra Sarper ◽  
Mehmet Saglam ◽  
Orhan Aydin
Keyword(s):  
Heat Transfer ◽  
Mixed Convection ◽  
Hot Spot ◽  
Experimental Studies ◽  
Vertical Channel ◽  
Working Fluid ◽  
Heat Sources ◽  
Ansys Fluent ◽  
Cooling Performance ◽  
Spot Temperature

In this study, convective heat transfer in a discretely heated parallel-plate vertical channel which simulates an IC package is investigated experimentally and numerically. Both natural and mixed convection cases are considered. The primary focus of the study is on determining optimum relative lengths of the heat sources in order to reduce the hot spot temperature and to maximize heat transfer from the sources to air. Various values of the length ratio and the modified Grashof number (for the natural convection case)/the Richardson number (for the mixed convection case) are examined. Conductive and radiative heat transfer is included in the analysis while air is used as the working fluid. Surface temperatures of the heat sources and the channel walls are measured in the experimental study. The numerical studies are performed using a commercial CFD code, ANSYS fluent. The variations of surface temperature, hot spot temperature, Nusselt number, and global conductance of the system are obtained for varying values of the working parameters. From the experimental studies, it is showed that the use of identical heat sources reduces the overall cooling performance both in natural and mixed convection. However, relatively decreasing heat sources lengths provides better cooling performance.

Heat Transfer Enhancement From a Blade Tip-Cap Using Metal Foams

2012 ◽  
Vol 134 (11) ◽  
Author(s):  
Owen Sengstock ◽  
Kamel Hooman
Keyword(s):  
Heat Transfer ◽  
Hot Spot ◽  
Metal Foams ◽  
Plate Temperature ◽  
Pin Fin ◽  
Heat Transfer Augmentation ◽  
Smooth Channel ◽  
Pin Fins ◽  
Blade Tip ◽  
Spot Temperature

3D numerical results are presented to compare the heat transfer augmentation from a plate by using pin fins and metal foams. It is observed that maximizing the inlet velocity and pores per inch maximizes the overall heat transfer rate. The thickness of the foam layer has minimal effect on overall rates of heat transfer, but great effect on the maximum plate temperature. It has been shown that an optimum thickness exists which minimizes the hot spot temperature. Hot spots are generally located in the corners where velocities are the lowest. While the pressure drop remains almost unaltered, the heat transfer increases by 146% and 12% compared with a smooth channel and the optimal pin-fin data available in the literature, respectively. Interestingly, the additional mass of the foams, to achieve this performance, is approximately one-quarter of the best pin-fin sink quoted above.

Thermal Analyzing of Disc Type Winding With Directed Oil Flow

2004 ◽  
Author(s):  
Seyyed Mehdi Peste ◽  
Mehdi Abloo
Keyword(s):  
Heat Transfer ◽  
Hot Spot ◽  
Iterative Solution ◽  
Oil Viscosity ◽  
Temperature Dependent ◽  
Local Circulation ◽  
Flow Paths ◽  
Oil Flow ◽  
Oil Density ◽  
Spot Temperature

In this paper, a model of a disc type winding for a transformer with directed oil flow is presented which utilizes a network of oil flow paths. Along each path segment, oil velocities and temperature rises are computed. The model includes temperature dependent oil density, resistivity, and oil viscosity and temperature and velocity dependent heat transfer and friction coefficients. Because of the non-linearity, an iterative solution is necessary. Temperature and oil velocities are computed and compared with experiment values. From this, the average winding temperature rise and the hot spot temperature can be determined. The model assumes the oil flows in definite paths and ignores local circulation, since we assume the oil flow is guided by means of oil flow washers, this assumption should be fairly accurate. The disc type winding is assumed to be subdivided into directed oil flow cooling paths.

Influence of insulation paper on the hot spot temperature of oil-immersed transformer winding

2021 ◽  
pp. 2140021
Author(s):  
Chuan Luo ◽  
Zhen-Gang Zhao ◽  
Yu-Yuan Wang ◽  
Ke Liang ◽  
Jia-Hong Zhang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Hot Spot ◽  
Transformer Oil ◽  
Heat Diffusion ◽  
Normal Operation ◽  
Measured Temperature ◽  
Conduction Model ◽  
Transfer Resistance ◽  
Actual Environment ◽  
Spot Temperature

The oil-immersed transformer is a crucial piece of equipment in the power system. Operating at the specified temperature is necessary to ensure the normal operation of the transformer. The insulation paper on the winding surface has a significant impact on the actual temperature of the transformers, which is often overlooked by researchers. The one-dimensional steady-state heat conduction model of the transformer is established by analyzing the heat diffusion process of winding to transformer oil. Atomic force microscope was used to observe the microsurface structure of insulation paper and copper. According to the experiment, the heat transfer resistance in the series process of heat transfer at [Formula: see text]C is 0.0138 m2 K/W. Space thermal circuit model of transformer is established by thermoelectricity analogy method, and the simulation circuit is optimized according to the boundary conditions set up in the actual environment. The results show that the error of the hot spot temperature is closer to the measured temperature and decreases by 2.5% when considering the thermal resistance of insulation paper.

Research of Temperature Field in Oil-Immersed Transformer Considering the Oil Speed

2014 ◽  
Vol 912-914 ◽  
pp. 1041-1045
Author(s):  
Guo Liang Yue ◽  
Yong Qiang Wang ◽  
Jie He ◽  
Hong Liang Liu
Keyword(s):  
Temperature Field ◽  
Hot Spot ◽  
Element Model ◽  
Thermal Coupling ◽  
Normal Range ◽  
Steady State Temperature ◽  
Oil Flow ◽  
Transformer Winding ◽  
The Mathematical Model ◽  
Spot Temperature

In this paper, we have Elaborated the mathematical model of temperature field and flow field of the oil-immersed transformer, and analysis its structure of thermal .We established a temperature finite element model of an oil-immersed transformer using the method of flow-solid-thermal coupling. Using the software of ANSYS, simulating on a 250MVA oil-immersed transformer, we obtain the steady-state temperature distribution and the winding hottest locations. Analyze the effect of oil-speed to the temperature field and location of the hot spot temperature of oil-immersed transformer. The results show that when oil flow rate is increases in the normal range, Transformer temperature rise corresponding slowly, and its location hottest temperature slightly pulled accordingly. The fiber measure different speeds Oil immersed transformer winding hot spot temperature to provide a basis for positioning.

Error Analysis of Transformer Hot Spot Temperature Measurement

2021 ◽  
Author(s):  
Zhengang Zhao ◽  
Zhengyu Yang ◽  
Yuyuan Wang ◽  
Ke Liang ◽  
Nengsi Jin ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Temperature Difference ◽  
Hot Spot ◽  
Heat Transfer Model ◽  
National Standard ◽  
Experimental Temperature ◽  
Transfer Model ◽  
Measuring Point ◽  
Temperature Measuring ◽  
Spot Temperature

According to the national standard GB/T 1094.7-2008, the method of hot spot measurement of oil-immersed transformer is used to place several temperature sensors inside the gasket within the predicted hot spot position to measure the temperature of winding transformer. The highest temperature measured is regarded as the hot spot temperature of transformer. Since the winding and gasket are bad conductors of heat, there exists certain temperature difference between the gasket and the hot spot temperature of the winding. In order to ensure safe operation of transformer, the thermal environment of temperature measuring point is analyzed and the discrete equation of boundary node is established. The parameters are set according to the heat transfer mode of the oil-immersed transformer and the temperature characteristics of each heat transfer node is analyzed. Gauss-Seidel Iteration method is used to calculate the theoretical value of the measuring point of the oil-immersed transformer and the heat transfer model of the measuring point is established for further analysis. The experimental platform of the oil-immersed transformer simulator is established according to the method described in the national standard and used to measure the hot spot temperature and winding surface temperature. The results show that when the winding temperature is 77 ℃, the heat transfer model of the temperature measuring point is 74.7 ℃ and the experimental temperature of the temperature measuring point is 74.9 ℃. The error between theoretical calculation temperature and experimental temperature is 0.2. As the temperature of the experiment increases, the temperature difference between the temperature point and the winding temperature gradually increases, and the maximum absolute error is 2.1 ℃.

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