Lightweight traction transformer

Abstract

The lightweight traction transformer comprises a transformer body, a traction air cooling assembly and an active cooling system, the transformer body is fixed to the two sides of the traction air cooling assembly, and the interior of the transformer body is communicated with the traction air cooling assembly through a liquid inlet flow channel and a liquid outlet flow channel to form a closed oil liquid circulation path; a heat exchange tank set and a flow guide rod structure are arranged in the traction air cooling assembly, a plurality of oil duct pipes are arranged in the heat exchange tank set and used for conducting heat exchange with transformer oil flowing through the heat exchange tank set, a flow guide rod is matched with a rotational flow paddle body to guide external air to form a C-shaped air flow path, rotational air gaps are formed between the oil duct pipes, and the heat dissipation efficiency is improved. A refrigerating coil and a compression refrigerating unit are arranged in the active cooling system, and the active cooling system is used for conducting deep cooling on oil liquid and enhancing the heat dissipation capacity under the high-load or extreme environment. The device is compact in structure and optimized in cooling path, has oil-gas coupling heat exchange capacity and active temperature control capacity, and is suitable for a rail transit traction system with high power density and high reliability.

Description

Technical Field

[0001] The present invention relates to the technical field of traction transformers, and particularly to a lightweight traction transformer. Background Art

[0002] With the rapid development of rail transit technology, higher requirements are put forward for transformer equipment in the electric traction system, especially in terms of complex operating environments, increased power density, and structural lightweighting. As a core component in systems such as EMUs and urban rail vehicles, the working stability and cooling efficiency of the traction transformer directly affect the running performance and safety of the entire vehicle.

[0003] In the prior art, the cooling methods of traction transformers mainly include air-cooled and oil-immersed cooling. Traditional oil-cooled transformers cool the oil through natural convection of internal hot oil or by setting up an external circulation pump, while some systems use an external heat exchanger combined with an axial flow fan for forced air cooling to improve the heat transfer efficiency.

[0004] However, the current common structures mainly have the following technical problems: In the existing systems, the transformer body, heat exchange components, and auxiliary cooling systems are often designed separately. Not only are the layouts complex, the volume large, and the weight high, but also there are many connection interfaces between systems and the reliability is low. Especially in rail vehicles with limited space in the car body, the installation is difficult and the maintenance cost is high.

[0005] Most of the existing heat exchangers are of plate-fin or shell-and-tube structures, and the utilization rate of external air flow is not high during actual operation. Especially when the train is running at high speed, the air flow cannot be effectively introduced into the heat exchange area, resulting in a significant reduction in the heat dissipation efficiency. At the same time, most systems do not design an active flow guiding structure, causing air flow disorder and further reducing the cooling performance.

[0006] Currently, most traction transformer cooling systems rely on natural heat dissipation or simple air-cooling methods, and it is difficult to meet the operating requirements under long-term high load or high temperature environments. Especially in extreme climate or tunnel scenarios, the oil temperature is likely to be too high, affecting the life of the transformer and even causing overheating failures. And most active cooling systems with refrigeration capabilities are independent additional devices and do not form a compact integrated cooling unit, with slow response and high energy consumption.

[0007] Therefore, there is an urgent need in the prior art for a lightweight traction transformer with a compact structure, high heat dissipation efficiency, and the ability to adapt to complex working conditions, which can realize the coupled heat exchange of oil and air flow in a limited space and has the active refrigeration ability at high temperatures, so as to comprehensively improve the operating safety and environmental adaptability of the rail transit traction system. Summary of the Invention

[0008] The present invention aims to solve one of the technical problems existing in the prior art or related technologies.

[0009] To this end, the technical solution adopted by the present invention is as follows: a lightweight traction transformer, comprising: a transformer main body, a traction air-cooling assembly, and an active cooling system. The transformer main body is fixed on both sides of the traction air-cooling assembly, and floating ears are fixedly installed on the surface of the transformer main body. An elastic member is provided on the bottom surface of the floating ear, and the other end of the elastic member is connected to a vehicle frame. The active cooling system is fixed on the top surface of the traction air-cooling assembly; The traction air-cooling assembly includes a cooling cylinder body, a heat exchange tank group and a flow guiding rod fixed inside the cooling cylinder body. Air inlet guiding ports and exhaust ports are respectively opened at both ends of the cooling cylinder body. A swirl paddle is fixedly installed inside the air inlet guiding port. One end of the flow guiding rod is rotatably installed with an exhaust shaft located inside the exhaust port. Liquid inlet channels and liquid outlet channels are provided on both sides of the cooling cylinder body and are respectively located at both ends. The liquid inlet channels and the liquid outlet channels are used to communicate with the inside of the transformer main body for oil liquid circulation. The heat exchange tank group includes heat exchange tanks and a plurality of oil duct pipes arranged inside the heat exchange tanks. Both ends of the oil duct pipes penetrate through the heat exchange tanks and are used to communicate with the liquid inlet channels and the liquid outlet channels to form an oil circuit. The active cooling system is used to actively cool the transformer oil liquid inside the cooling cylinder body.

[0010] Through this structure, the combined and efficient heat dissipation of oil liquid circulation and air heat exchange is realized in a compact space, improving the operation reliability of the transformer.

[0011] In a possible implementation manner, the transformer main body and the cooling cylinder body are of a sealed housing structure, and transformer oil liquid is filled inside the transformer main body and is communicated with the inside of the cooling cylinder body. The port of the liquid inlet channel is connected with a circulating pump group located inside the transformer main body.

[0012] This structure ensures the establishment of an oil liquid closed loop, improving the heat circulation efficiency and reducing the environmental impact.

[0013] In a possible implementation manner, the heat exchange tank is of a metal cylinder structure, and the outer periphery of the heat exchange tank is hermetically joined with the inside of the cooling cylinder body. The ports of the oil duct pipes penetrate through the end faces of the heat exchange tanks and are used to communicate with the liquid inlet channels and the liquid outlet channels.

[0014] Through the design of the metal cylinder and the sealing structure, the heat conduction efficiency is improved and oil liquid leakage is prevented.

[0015] In a possible implementation manner, a plurality of the oil duct pipes are arranged in parallel with each other, and a plurality of heat exchange tanks are evenly divided into several groups. Each group of heat exchange tanks is arranged in a spiral shape and is radially arranged from the axis of the heat exchange tank group to the outside of the heat exchange tank group. And each group of heat exchange tank groups is arranged in a circumferential array.

[0016] Specifically, by adopting the spiral arrangement, a swirling air gap is formed between adjacent oil duct pipes, facilitating the flow of external air between adjacent oil duct pipes.

[0017] This arrangement enhances air disturbance and heat transfer effect, and improves the natural heat dissipation efficiency.

[0018] In a possible implementation, the air inlet guide is in a horn shape. The outer periphery of the swirl paddle body is provided with swirl blades, and the outer periphery of the swirl blades is fixedly connected to the inner wall of the air inlet guide. The swirl paddle body is in a water droplet shape, and a diversion head is fixedly connected to the end of the swirl paddle body for diffusing and guiding the air flow.

[0019] This structural design effectively induces the intake air to form a stable swirl, expands the air flow coverage range, and improves the utilization rate of the cooling air.

[0020] In a possible implementation, an air flow gap communicating with the inside of the heat exchange tank is provided on the outer periphery of the diversion rod. The diversion inclined surfaces at both ends of the diversion rod are in an arc-shaped inclined surface shape for guiding the air flow to form a C-shaped air path. The diversion structure optimizes the air path and improves the air flow penetration force and speed during the heat dissipation process.

[0021] In a possible implementation, bearing brackets are provided at one end of the diversion rod and the inner side of the exhaust port for rotatably installing the exhaust shaft.

[0022] The operation stability and structural strength of the diversion device are improved through the bearing installation structure.

[0023] In a possible implementation, the active cooling system is internally provided with a refrigeration coil, and the refrigeration coil is connected to a compression refrigeration unit for cooling the transformer oil inside the traction air-cooling assembly to reduce the oil temperature and improve the overall heat dissipation efficiency.

[0024] This active cooling system provides an effective supplementary cooling means for high-load scenarios and ensures the stable operation of the system under extreme conditions. The beneficial effects obtained by the present invention are as follows: 1. In the present invention, by integrally arranging the transformer main body and the traction air-cooling assembly structure and adopting a closed oil circulation system, the efficient cooling of the traction transformer is realized, the thermal stability and continuous operation ability of the equipment are effectively improved, the high-speed air flow during the vehicle movement is fully utilized, and the working energy consumption is reduced.

[0025] 2. In the present invention, the heat exchange tank group arranged inside the traction air-cooling assembly adopts a spiral arrangement to arrange the oil duct pipes, and in combination with the diversion structures such as the swirl paddle body and the diversion rod, the driving air flow during the operation of the rail vehicle is fully utilized to realize natural heat dissipation. While improving the heat dissipation efficiency, the equipment weight is effectively reduced, and it has the advantage of light weight.

[0026] 3. In the present invention, the active cooling system adopts a deep cooling structure composed of a refrigeration coil and a compression refrigeration unit, which can actively cool the oil quickly under high load or high temperature environments, construct a dual heat dissipation path, and significantly enhance the operating safety and adaptability of the transformer system in complex environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a schematic diagram of the overall structure of an embodiment of the present invention; Figure 2 is a schematic diagram of the installation structure of the transformer main body and the traction air-cooling assembly of an embodiment of the present invention; Figure 3 is a schematic diagram of the installation structure of the traction air-cooling assembly and the active cooling system of an embodiment of the present invention; Figure 4 is a schematic diagram of the internal structure of the traction air-cooling assembly of an embodiment of the present invention; Figure 5 is a schematic diagram of the cross-sectional structure of the heat exchange tank group and the flow guiding rod of an embodiment of the present invention; Figure 6 is a schematic diagram of the structure of the heat exchange tank group of an embodiment of the present invention; Figure 7 is a schematic diagram of the structure of the swirl paddle of an embodiment of the present invention; Figure 8 is a schematic diagram of the array arrangement structure of the oil duct tubes of an embodiment of the present invention.

[0028] Reference Numerals: 100, transformer main body; 110, floating ear; 120, vehicle frame; 111, elastic member; 200, traction air-cooling assembly; 210, cooling cylinder; 220, heat exchange tank group; 230, flow guiding rod; 240, swirl paddle; 250, exhaust shaft; 211, liquid inlet channel; 212, liquid outlet channel; 213, air gap; 214, air inlet guide port; 215, exhaust port; 221, heat exchange tank; 222, oil duct tube; 231, flow guiding inclined surface; 241, swirl blade; 242, sub-guide head; 300, active cooling system. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] To make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings. It should be noted that, without conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

[0030] It should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present invention.

[0031] A lightweight traction transformer provided by some embodiments of the present invention will be described below in conjunction with the accompanying drawings. Embodiment 1:

[0032] Combined with Figures 1-8 As shown, a lightweight traction transformer provided by the present invention includes a transformer main body 100, a traction air-cooling assembly 200, and an active cooling system 300. The transformer main body 100 is fixed on both sides of the traction air-cooling assembly 200 and is used to provide the main voltage transformation function. A floating ear 110 is fixedly installed on the outer surface of the transformer main body 100. An elastic member 111 is provided on the bottom surface of the floating ear 110, and the other end of the elastic member 111 is connected to a vehicle frame 120, which is used to connect with the vehicle body and absorb vibrations. The active cooling system 300 is fixedly installed on the top surface of the traction air-cooling assembly 200 and is used to enhance heat dissipation.

[0033] The traction air-cooling assembly 200 includes a cooling cylinder 210, and a heat exchange tank group 220 and a guide rod 230 are fixedly installed inside the cooling cylinder 210. Air inlet ducts 214 and an exhaust port 215 are respectively opened at both ends of the cooling cylinder 210 to realize an air flow channel. A swirl paddle 240 is fixedly installed inside the air inlet duct 214. Swirl blades 241 are provided on the outer periphery of the swirl paddle 240, and a split guide head 242 is fixedly connected to the front end of the swirl paddle 240, which is used to generate swirl during air intake and enhance air disturbance, thereby improving the heat exchange efficiency.

[0034] The guide rod 230 is arranged at the center of the cooling cylinder 210. One end of the guide rod 230 is installed inside the exhaust port 215 through a bearing bracket, and the bearing bracket supports the rotational installation of an exhaust shaft 250 to realize the rotational function of the guide rod 230. Guide inclined surfaces 231 are provided at both ends of the guide rod 230, which are in an arc-shaped inclined surface shape and are used to change the air flow direction and guide it to flow along a C-shaped path.

[0035] Liquid inlet channels 211 and liquid outlet channels 212 are respectively provided on both sides of the cooling cylinder 210. The liquid inlet channels 211 and the liquid outlet channels 212 are respectively communicated with the oil cavities of the transformer main body 100. Both the transformer main body 100 and the cooling cylinder 210 are of a sealed housing structure, and transformer oil is filled inside. The port of the liquid inlet channel 211 is connected to a circulating pump group inside the transformer main body 100. When the traction transformer works, the circulating pump group is started to push the high-temperature transformer oil to flow into the cooling cylinder 210 of the traction air-cooling assembly 200 through the liquid inlet channel 211.

[0036] Inside the temperature-lowering cylinder body 210, the arranged heat exchange tank group 220 includes several heat exchange tanks 221. The heat exchange tanks 221 are of metal cylinder structures, and their outer peripheries are hermetically joined to the inner wall of the temperature-lowering cylinder body 210. Inside each heat exchange tank 221, several oil channel pipes 222 are arranged. The oil channel pipes 222 penetrate through the end faces of the heat exchange tanks 221 and are respectively communicated with the liquid inlet flow channel 211 and the liquid outlet flow channel 212 to form an oil liquid loop. The several oil channel pipes 222 are arranged in parallel with each other. The multiple heat exchange tanks 221 form several groups, which are arranged in a spiral shape and radially arranged from the axis of the heat exchange tank group 220 to the outside. Each group of heat exchange tank groups 220 is arranged in an array along the circumferential direction. Under this arrangement structure, a spiral air gap is formed between the oil channel pipes 222, enabling the air flow to flow efficiently between the adjacent oil channel pipes 222 and conduct heat exchange.

[0037] Air enters from the air inlet guide 214, forms a spiral air flow after being disturbed by the swirl paddle 240 and its swirl blades 241, and then turns via the guide inclined plane 231 to form a C-shaped air path and flow around the outside of the heat exchange tank group 220. The external air takes away the heat when flowing through the outer wall of the oil channel pipe 222, thereby realizing the cooling of the high-temperature oil liquid. The cooled oil liquid flows back to the transformer main body 100 through the liquid outlet flow channel 212 to form a closed-loop oil liquid circulation system, supporting the overall heat dissipation function of the transformer.

[0038] During operation, when natural air cooling heat dissipation is insufficient to meet the heat dissipation requirements, the active temperature-lowering system 300 is started. A refrigeration coil is provided inside it, and the refrigeration coil is communicated with a compression refrigeration unit for deeply cooling the oil liquid in the temperature-lowering cylinder body 210. This refrigeration mechanism can effectively improve the temperature-lowering ability and ensure the normal operation of the system under high load or high-temperature environments.

[0039] In summary, the present invention combines the oil liquid cooling circulation system, the air flow guiding structure and the active temperature-lowering device to construct a lightweight traction transformer cooling system that is efficient, compact and applicable to rail transit vehicles, effectively improving the stability and reliability of the transformer operation. Embodiment 2:

[0040] On the basis of Embodiment 1, in order to further improve the cooling capacity of the traction transformer under high load or extreme environments, the structure of the active temperature-lowering system 300 in this embodiment is optimized and designed, adopting an integrated refrigeration module structure to improve the temperature-lowering efficiency and operation reliability.

[0041] The active temperature-lowering system 300 includes a housing, a refrigeration coil, a compression refrigeration unit, a condensation fan and a guide cover assembly. Among them, the refrigeration coil is installed inside the housing and arranged around the main oil liquid circulation channel to form a casing heat exchange structure. Specifically: The housing is of a cylindrical structure, made of aluminum alloy or stainless steel, and has good heat conductivity and structural strength; Inside the housing is an inner cavity, in which a coiled refrigeration coil is arranged. The refrigeration coil adopts a copper fin structure to increase the heat exchange area and efficiency with the oil fluid. Outside the housing is a compression refrigeration unit, which is connected to the refrigeration coil through a connecting pipeline to form a closed refrigerant circulation loop. The refrigeration system uses an environmentally friendly R134a or R1234yf refrigerant. To enhance condensation heat transfer, a condenser and a condensation fan are arranged on one side outside the housing. The condensation fan is used to quickly condense the high-temperature gaseous refrigerant discharged from the compressor into a liquid state. The deflector assembly is arranged outside the refrigeration coil and is used to guide the oil fluid to fully contact the refrigeration coil in the inner cavity of the housing, improving the heat transfer efficiency.

[0042] During operation, when it is detected that the temperature of the transformer oil fluid exceeds the set threshold, the control system automatically starts the compression refrigeration unit. The refrigerant circulates inside the refrigeration system, and the surface temperature of the refrigeration coil rapidly decreases, thereby quickly cooling the transformer oil fluid in contact with it. The cooled oil fluid continues to participate in the heat exchange process in the traction air-cooling assembly 200 and combines with the natural air flow to achieve secondary cooling, forming a "dual-cooling path" heat dissipation mode.

[0043] In addition, temperature sensor interfaces and control circuit interfaces are reserved inside the active cooling system 300, which can be dynamically adjusted according to the actual operating environment to achieve closed-loop control of the oil temperature.

[0044] Through the above structural optimization design, the active cooling system 300 in this embodiment has the following advantages: Fast refrigeration response speed; compact installation structure, easy to integrate; high heat exchange efficiency, meeting the usage requirements under various working conditions; Improve the system safety redundancy and heat dissipation capacity, suitable for various traction working conditions such as urban rail and main line trains.

[0045] This embodiment can be combined with other parts of Embodiment 1 and can also be adjusted according to different operating conditions to achieve function expansion without changing its core structure and principle.

[0046] The working principle and usage process of the present invention: A lightweight traction transformer provided by the present invention combines three core modules: a transformer body, a traction air-cooling assembly, and an active cooling system, and realizes efficient cooling of the traction transformer through the dual cooperative mechanism of internal transformer oil circulation and air-cooled heat exchange. Its working principle is mainly as follows: Principle of oil heat exchange cycle: When the traction transformer is in operation, the transformer oil inside the transformer main body 100 is heated and its temperature rises. After the circulation pump group starts, the hot oil is transported through the liquid inlet channel 211 to the cooling cylinder 210 inside the traction air-cooling assembly 200 and passes through the inside of the oil duct pipe 222.

[0047] Cooling process of the internal heat exchange mechanism: After the hot oil enters the cooling cylinder 210, it flows through the heat exchange tank group 220. Some of the oil duct pipes 222 arranged inside the heat exchange tank 221 exchange heat with the external air, thereby discharging the heat. The oil returns to the transformer main body 100 through the liquid outlet channel 212 to complete the closed-loop cycle.

[0048] Function of the air flow path and the guiding structure: External air enters from the air inlet guide 214 and forms a spiral-enhanced air flow under the action of the rotating blades 241 and the split guide head 242 of the swirl paddle 240. The air flow forms a C-shaped channel through the guiding inclined plane 231 and enters the heat exchange tank group 220, flowing internally in the spiral air gap formed between adjacent oil duct pipes 222, facilitating the flow of external air between adjacent oil duct pipes 222, forming a heat exchange with the oil duct pipes 222, making full use of the air flow movement during the running of the rail vehicle, and enabling the air flow to flow through the inside of the heat exchange tank 221.

[0049] Enhanced heat dissipation of the active cooling system: When natural air cooling cannot meet the cooling requirements, the active cooling system 300 starts, and deeply cools the transformer oil in the cooling cylinder 210 through the refrigeration coil and the compression refrigeration unit inside it, improving the heat dissipation efficiency and ensuring the safe operation of the system.

[0050] In the description of this specification, the descriptions of terms such as "one embodiment", "some embodiments", "specific embodiments", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0051] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and purposes of the present invention. The scope of the present invention is defined by the claims and their equivalents.

Claims

1. A lightweight traction transformer, characterized in that, Including: A transformer main body (100), a traction air-cooling assembly (200), and an active cooling system (300). The transformer main body (100) is fixed on both sides of the traction air-cooling assembly (200), and a floating ear (110) is fixedly installed on the surface of the transformer main body (100). An elastic member (111) is provided on the bottom surface of the floating ear (110), and the other end of the elastic member (111) is connected to a vehicle frame (120). The active cooling system (300) is fixed on the top surface of the traction air-cooling assembly (200); The traction air-cooling assembly (200) includes a cooling cylinder body (210), a heat exchange tank group (220) and a flow guiding rod (230) fixed inside the cooling cylinder body (210). Air inlet guides (214) and exhaust ports (215) are respectively formed at both ends of the cooling cylinder body (210). A swirl paddle body (240) is fixedly installed inside the air inlet guide (214). One end of the flow guiding rod (230) is rotatably installed with an exhaust shaft (250) inside the exhaust port (215). Liquid inlet channels (211) and liquid outlet channels (212) are provided on both sides of the cooling cylinder body (210) and are respectively located at both ends. The liquid inlet channels (211) and the liquid outlet channels (212) are used to communicate with the inside of the transformer main body (100) for oil liquid circulation. The heat exchange tank group (220) includes heat exchange tanks (221) and a plurality of oil channel pipes (222) arranged inside the heat exchange tanks (221). Both ends of the oil channel pipes (222) penetrate through the heat exchange tanks (221) for communicating with the liquid inlet channels (211) and the liquid outlet channels (212) to form an oil circuit. The active cooling system (300) is used to actively cool the transformer oil liquid inside the cooling cylinder body (210).

2. The lightweight traction transformer according to claim 1, characterized in that, The transformer main body (100) and the cooling cylinder body (210) are of a sealed housing structure. Transformer oil liquid is filled inside the transformer main body (100) and is communicated with the inside of the cooling cylinder body (210). The port of the liquid inlet channel (211) is connected with a circulation pump group located inside the transformer main body (100).

3. A lightweight traction transformer according to claim 1, characterized in that, The heat exchange tank (221) is of a metal cylinder structure, and the outer periphery of the heat exchange tank (221) is hermetically joined with the inside of the cooling cylinder body (210). The ports of the oil channel pipes (222) penetrate through the end faces of the heat exchange tanks (221) for communicating with the liquid inlet channels (211) and the liquid outlet channels (212).

4. A lightweight traction transformer according to claim 1, characterized in that A plurality of the oil channel pipes (222) are arranged in parallel with each other, and a plurality of heat exchange tanks (221) are evenly divided into several groups. Each group of heat exchange tanks (221) is arranged in a spiral shape and radiates outward from the axis of the heat exchange tank group (220), and each group of heat exchange tank groups (220) is arranged in a circumferential array.

5. A lightweight traction transformer according to claim 1, characterized in that, The air inlet guide (214) is in a horn shape. Swirl blades (241) are provided on the outer periphery of the swirl paddle body (240), and the outer periphery of the swirl blades (241) is fixedly connected to the inner wall of the air inlet guide (214). The swirl paddle body (240) is in a water droplet shape, and a split guide head (242) is fixedly connected to the end of the swirl paddle body (240) for guiding the diffusion of air flow.

6. A lightweight traction transformer according to claim 1, characterized in that, An air flow gap (213) communicating with the inside of the heat exchange tank (221) is provided on the outer periphery of the flow guide rod (230), and the flow guide inclined surfaces (231) at both ends of the flow guide rod (230) are arc-shaped inclined surfaces for guiding the air flow to form a C-shaped air path.

7. The lightweight traction transformer according to claim 1, characterized in that, Bearing brackets are provided at one end of the flow guide rod (230) and the inner side of the exhaust port (215) for rotatably mounting the exhaust shaft (250).

8. A lightweight traction transformer according to claim 1, wherein, The active cooling system (300) is internally provided with a refrigeration coil, and the refrigeration coil is communicated with a compression refrigeration unit for cooling the transformer oil inside the traction air-cooling assembly (200) to reduce the oil temperature and improve the overall heat dissipation efficiency.

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