A power electronic transformer with winding embedded liquid cooling channels

Abstract

This application relates to the field of transformer technology, specifically to a power electronic transformer with an embedded liquid-cooling channel in the windings. The transformer includes a power conversion module, a high-frequency isolation transformer, and a control module. The input terminal of the power conversion module is used to connect to an input power supply. The high-frequency isolation transformer includes a magnetic core, a primary winding, and a secondary winding. The control module controls the power conversion process of the power conversion module. Specifically, the primary winding and / or the secondary winding includes multiple conductive winding plates. The high-frequency isolation transformer also includes a liquid-cooling plate and an embedded liquid-cooling channel disposed within the liquid-cooling plate. The liquid-cooling plate and the multiple conductive winding plates are stacked, and the embedded liquid-cooling channel contains coolant. This invention enhances the internal heat dissipation capacity of the high-frequency isolation transformer through embedded liquid cooling, better meeting the engineering requirements of high power density, miniaturization, and continuous operation.

Description

Technical Field

[0001] This application relates to the field of transformer technology, and specifically to a power electronic transformer with a winding-embedded liquid cooling channel. Background Technology

[0002] A power electronic transformer is a power conversion device that combines power electronic conversion technology with high-frequency isolation transformer technology. Compared with traditional power frequency transformers, power electronic transformers are characterized by their small size, light weight, strong controllability, ease of implementing AC / DC interfaces, multi-port access, and bidirectional energy flow. In recent years, power electronic transformers have been increasingly applied in scenarios such as new energy grid connection, DC power distribution, energy storage systems, electric vehicle charging, rail transit traction power supply, ship power systems, and smart microgrids.

[0003] In power electronic transformers, high-frequency isolation transformers are key components for achieving high-frequency isolation and voltage transformation. To adapt to high-frequency operation, the windings in high-frequency isolation transformers often employ structures such as planar windings, copper foil windings, or laminated conductive winding plates. Under high-frequency, high-current operating conditions, the primary and secondary windings generate significant heat due to conductor resistance, skin effect, and proximity effect. Especially in laminated winding structures, where conductive winding plates are stacked on top of each other, internal heat does not easily dissipate quickly. If this heat cannot be dissipated in time, it may lead to aging of insulation materials, increased winding resistance, deterioration of magnetic material performance, derating of power devices, and even reduced overall efficiency and operational failure of the power electronic transformer.

[0004] To address the heat dissipation problem of power electronic transformers and their high-frequency isolation transformers, existing technologies typically employ external cooling methods. A common approach involves installing fans, air ducts, and ventilation holes outside the high-frequency isolation transformer or power electronic transformer cabinet, using airflow to remove heat from the equipment surface. This method is relatively simple in structure, low in cost, and easy to maintain, making it suitable for low-to-medium power applications or scenarios with low heat flux density. However, air cooling relies primarily on convective heat transfer between the air and the outer surface. Air has limited thermal conductivity and heat capacity. When heat from the windings is concentrated within the laminated structure, the heat must first be transferred from the conductive winding plate through the insulation layer, frame, potting layer, or outer shell to the outer surface before being carried away by airflow. This results in a long heat transfer path, making it difficult to eliminate internal hotspots promptly. Another existing technology involves installing heat sinks, heat dissipation base plates, thermal pads, or external cold plates outside the high-frequency isolation transformer. This method enhances the heat dissipation capacity of the outer surface compared to simple air cooling, and is particularly suitable for scenarios where the transformer is fixed to a metal base plate or liquid-cooled substrate. However, these external heat dissipation methods are usually still indirect heat dissipation from the inside out, with a long thermal resistance path between the cooling location and the actual heat-generating location of the winding. Some existing technologies incorporate liquid cooling plates, cooling pipes, or cooling chambers within the transformer's overall casing or cabinet, allowing the coolant to circulate outside the transformer or within the mounting base. This method offers higher heat capacity and heat exchange capability compared to air cooling, improving the overall heat dissipation of the equipment. However, most existing liquid cooling structures are located outside the transformer, on the outer casing, outside the magnetic core, or on the mounting base, primarily cooling the outer surface of the transformer or the entire casing, without directly contacting the stacked heat-generating areas of the primary and secondary windings. For high-frequency isolation transformers formed by stacked conductive winding plates, multiple layers of insulation and structural materials are still required between the internal hot spots of the windings and the external liquid cooling plate, resulting in problems such as delayed heat transfer, difficulty in suppressing localized temperature rises, and a mismatch between cooling efficiency and the location of the hot spots.

[0005] In summary, while existing technologies can improve the heat dissipation of power electronic transformers through methods such as air cooling, external heat sinks, external cold plates, or liquid cooling of the casing, these solutions generally suffer from problems such as the cooling structure being far from the heat source inside the windings, long heat transfer paths, insufficient suppression of hot spots in the middle of the lapped windings, and difficulty in distributing heat dissipation capacity according to different heat-generating areas. As power electronic transformers develop towards higher frequencies, higher power densities, and smaller compact designs, heat is more easily concentrated inside the primary and secondary windings, making it difficult to meet the near-field cooling requirements of the windings by relying solely on external heat dissipation. Summary of the Invention

[0006] To address the above problems, this invention provides a power electronic transformer with an embedded liquid-cooled channel in the winding, comprising a power conversion module, a high-frequency isolation transformer, and a control module. The input terminal of the power conversion module is connected to an input power supply, and the output terminal of the power conversion module is electrically connected to the primary side of the high-frequency isolation transformer. The power conversion module converts the input electrical energy into electrical energy suitable for high-frequency transmission by the high-frequency isolation transformer. The high-frequency isolation transformer includes a magnetic core, a primary winding, and a secondary winding. The primary winding is electrically connected to the power conversion module, and the secondary winding is connected to the output terminal or a load. The control module controls the power conversion process of the power conversion module. Specifically, the primary winding and / or the secondary winding includes multiple conductive winding plates, and the high-frequency isolation transformer also includes a liquid-cooled plate and an embedded liquid-cooled channel disposed within the liquid-cooled plate. The liquid-cooled plate and the multiple conductive winding plates are stacked, and the embedded liquid-cooled channel contains coolant.

[0007] This invention designs the primary and / or secondary windings as a structure formed by stacking multiple conductive winding plates. Liquid cooling plates with embedded liquid cooling channels are stacked adjacent to the conductive winding plates, allowing the coolant to transfer heat from the surface of the high-frequency isolation transformer directly to the heat source near the windings for near-field heat exchange. During operation, the conductive winding plates experience resistive losses, skin effect losses, and proximity effect losses due to high-frequency, high-current flow. Heat is first transferred from the conductive winding plates to the adjacent liquid cooling plates, then through the channel walls of the liquid cooling plates to the coolant within the embedded liquid cooling channels, where it is continuously carried away by the flowing coolant. This creates a short-path heat transfer channel between the conductive winding plates, the liquid cooling plates, and the coolant. Unlike traditional air cooling or external heat sinks that rely primarily on surface heat transfer and have long heat transfer paths, this invention features a liquid cooling structure embedded near the winding stacked structure. This brings the cooling point closer to the hot spots inside the winding, enabling more timely reduction of temperature rise in the middle of the conductive winding board, the interlayer stacked area, and the high current density region. Furthermore, the liquid cooling plate and winding board are combined in a stacked manner, facilitating modular manufacturing and assembly, and achieving near-field liquid cooling of the winding without directly damaging the conductive winding structure. Therefore, it features a short heat dissipation path, high heat exchange efficiency, more uniform temperature distribution, and suitability for high-frequency, high-power-density power electronic transformers.

[0008] Furthermore, the coolant is one or more of fluorinated liquid, silicone oil, synthetic ester insulating coolant, and mineral insulating oil. These coolants have low conductivity, good electrical insulation performance, and low magnetic loss characteristics, making them less likely to form obvious conductive paths or generate significant additional losses in the alternating electromagnetic field environment of high-frequency isolation transformers. Since the embedded liquid cooling channel of this invention is located within the liquid cooling plate, and the liquid cooling plate is stacked with multiple conductive winding plates, the coolant is positioned relatively close to the primary winding and / or secondary winding. Therefore, the coolant not only needs to remove heat from the windings but also needs to prevent insulation risks caused by leakage, penetration, or local electric field coupling. Fluorinated liquids typically have good chemical stability, low conductivity, and good insulation safety, making them suitable for use near high-frequency electrical components; silicone oil has good thermal stability, insulation performance, and material compatibility, making it suitable for long-term cyclic cooling; synthetic ester insulating coolants combine insulation, thermal conductivity, and good heat aging resistance, improving reliability under high-temperature operation; mineral insulating oil is technologically mature and has stable insulation performance, making it suitable for cooling and insulation applications in power equipment. Therefore, the aforementioned coolant can carry away the heat transferred from the conductive winding plate through flow convection within the embedded liquid cooling channel, while reducing the risk of the cooling medium participating in conductivity, dielectric loss, or electromagnetic loss. This allows the present invention to achieve near-field liquid cooling of the winding while also ensuring heat dissipation efficiency, electrical insulation safety, and high-frequency operation stability.

[0009] Furthermore, it also includes a cooling circulation module, which is connected to the inlet and outlet of the embedded liquid cooling channel.

[0010] Furthermore, the control module is electrically connected to the cooling circulation module to control the coolant circulation status of the cooling circulation module. The cooling circulation module includes a storage unit, a pumping unit, a heat exchange unit, a filtration unit, a flow regulation unit, and supply and return pipelines. The storage unit stores coolant, the pumping unit provides power for coolant circulation, and the supply pipeline delivers coolant to the inlet end of the embedded liquid cooling channel. After entering the embedded liquid cooling channel within the liquid cooling plate, the coolant flows along the channel through the adjacent area of ​​the conductive winding plate, absorbing heat transferred from the conductive winding plate, and then flows back to the cooling circulation module from the outlet end via the return pipeline. The heat exchange unit releases the heat carried by the returning coolant to the external environment or the secondary cooling circuit, the filtration unit removes particulate impurities that may be generated during coolant circulation, and the flow regulation unit regulates the flow rate of coolant entering the embedded liquid cooling channel. Through the above-described cycle, the cooling cycle module can continuously supply the liquid cooling plate with coolant at a low temperature and with a controllable flow rate, and bring the coolant back after absorbing heat for heat exchange and cooling, thereby forming a stable closed-loop cooling cycle and improving the continuity and reliability of near-field heat dissipation of the winding.

[0011] Furthermore, the liquid cooling plate is equipped with an inlet and an outlet. The embedded liquid cooling channel includes an inlet manifold connected to the inlet, an outlet manifold connected to the outlet, and multiple parallel liquid cooling branches. One end of each of the parallel liquid cooling branches is connected to the inlet manifold, and the other end is connected to the outlet manifold. Compared with a single-path serpentine channel, multiple parallel liquid cooling branches can simultaneously cover a larger area of ​​the adjacent region of the conductive winding plate, enabling the liquid cooling plate to achieve a planar heat dissipation effect and preventing cooling from being concentrated on only a local path. At the same time, the parallel structure can shorten the flow length of a single liquid cooling branch, reduce the overall flow resistance and pressure drop, and make the coolant more likely to circulate stably. Since each parallel liquid cooling branch can be arranged to correspond to the middle, edge, lead end, or other heat-generating areas of the winding, it is beneficial to improve the liquid cooling plate's coverage of different heat-generating areas, reduce local hot spots in the winding, improve the temperature uniformity of the laminated winding structure, and improve the heat dissipation reliability of the high-frequency isolation transformer under high power density operating conditions.

[0012] Furthermore, along the width direction of the liquid-cooled plate, the width of the parallel liquid-cooled branches in the central region is greater than the width of the parallel liquid-cooled branches in the edge region. Typically, the central region of the conductive winding plate is more prone to higher temperature rises due to factors such as interlayer stacking, longer heat diffusion paths, and localized heat accumulation. With a wider central parallel liquid-cooled branch, its flow cross-sectional area increases, flow resistance decreases, and coolant is more easily distributed to the central region, thereby enhancing its heat-carrying capacity for the hot spots in the central winding. The relatively smaller width of the liquid-cooled branches in the edge region can moderately constrain the flow rate of the edge branches, preventing excessive coolant flow to the edge regions with relatively lower heat dissipation requirements. Thus, without significantly increasing the overall structural complexity, the flow distribution of each parallel branch can be improved, the maximum temperature rise in the central region can be reduced, the temperature gradient along the winding width direction can be decreased, and the temperature uniformity and long-term operational reliability of the laminated winding structure can be improved.

[0013] Furthermore, a transverse branch is provided between two adjacent parallel liquid-cooling branches, and the transverse branch is connected to each of the two adjacent parallel liquid-cooling branches. When the flow rate of a certain parallel liquid-cooling branch decreases due to processing errors, local bubble retention, impurity deposition, or changes in channel resistance, the coolant can be redistributed among the adjacent liquid-cooling branches through the transverse branch, avoiding insufficient cooling in the winding area corresponding to that branch. At the same time, the transverse branch can also alleviate the pressure difference between different parallel liquid-cooling branches, making the coolant flow distribution more balanced and reducing the problem of excessively high or low local flow velocities. As a result, the liquid-cooled plate can form a more stable flow field among multiple branches, improve the continuous heat dissipation capacity of different areas of the conductive winding plate, reduce the risk of local hot spots, and improve the temperature uniformity and operational reliability of the laminated winding structure.

[0014] Furthermore, the outer side of the liquid cooling plate is equipped with spaced magnetic heat-conducting sheets. This gives the structure both leakage magnetic confinement and auxiliary heat conduction. On the one hand, the magnetic permeability of the magnetic heat-conducting sheets is higher than that of the liquid cooling plate substrate material and the surrounding air, which can form a local low magnetic resistance region on the outer side of the liquid cooling plate. This allows some of the leakage magnetic field around the liquid cooling plate or on the outer side of the winding to preferentially distribute along the magnetic heat-conducting sheets, thereby reducing the diffusion of the leakage magnetic field into the external space and reducing the induced losses and additional temperature rise that may occur when the leakage magnetic field passes through the surrounding conductive structure. On the other hand, by adhering to the outer side of the liquid cooling plate, the magnetic heat-conducting sheets can play a planar diffusion and auxiliary conduction role for the local heat of the liquid cooling plate, making the heat absorbed by the winding absorbed by the liquid cooling plate more evenly distributed and released outward. Since the multiple magnetic heat-conducting sheets are spaced apart, rather than being a continuous whole structure, the shunting effect of continuous magnetic or conductive structures on the main magnetic flux path can be reduced, and the risk of large-area eddy currents or local thermal stress concentration under high-frequency alternating fields can be reduced. This enhances the heat dissipation effect while improving the electromagnetic compatibility and operational stability of the power electronic transformer.

[0015] Furthermore, the magnetic heat-conducting sheet is made of one or more of ferrite sheets, nanocrystalline magnetic sheets, or amorphous magnetic sheets. Ferrite sheets possess high permeability and resistivity, providing a localized low-resistivity path for the leakage magnetic field around the liquid cooling plate, while avoiding significant eddy current losses as with continuous metal plates. Nanocrystalline and amorphous magnetic sheets have high permeability and good soft magnetic properties, guiding and confining the leakage magnetic field outside the winding or around the liquid cooling plate, thereby reducing external leakage magnetic radiation and its induced heating on surrounding conductive structures. The magnetic heat-conducting sheet made of the aforementioned magnetic materials can also form an auxiliary heat-conducting path with the liquid cooling plate, allowing some of the heat absorbed by the liquid cooling plate to diffuse outwards, alleviating localized heat concentration. Therefore, this material selection achieves a balance between leakage magnetic constraint, reduced additional losses, and auxiliary heat dissipation from the liquid cooling plate without significantly interfering with the main magnetic flux path of the core, which is beneficial for improving the efficiency, electromagnetic compatibility, and long-term operational stability of power electronic transformers.

[0016] Furthermore, the cooling circulation module includes a pumping unit, and a control module controls the pumping unit to supply coolant to the embedded liquid cooling channel in a pulsed manner. This creates periodic flow rate variations in the coolant within the liquid cooling channel, thereby enhancing the scouring and disturbance effect of the coolant on the channel wall, reducing the formation of a stable thermal boundary layer near the channel wall, and improving the convective heat transfer efficiency between the coolant and the channel wall of the liquid cooling plate. Compared to constant flow rate supply, pulsed supply can improve instantaneous heat transfer capacity without a significant increase in average flow rate, allowing the liquid cooling plate to more effectively remove heat transferred from the conductive winding plate. Simultaneously, the periodic pressure and flow rate fluctuations also help reduce local bubble retention and microparticle deposition within the channel, reducing the risk of uneven flow or local blockage in parallel liquid cooling branches. Therefore, while considering pumping energy consumption, the heat dissipation efficiency and flow stability of the embedded liquid cooling channel can be improved, further reducing the temperature rise of winding hot spots and enhancing the long-term operational reliability of the power electronic transformer.

[0017] The beneficial effects of this invention are: (1) Compared with traditional external air cooling or external heat sink, the present invention has a shorter heat transfer path and can more directly remove the heat generated when the winding is working.

[0018] (2) By setting liquid cooling plates at adjacent positions of the conductive winding plate, the present invention allows the coolant to be close to the interlayer heat source, which is beneficial to reduce the hot spot temperature in the middle of the winding and the interlayer region.

[0019] (3) The present invention reduces the temperature difference between the local high temperature zone and the low temperature zone, thereby improving the thermal stability of the high frequency isolation transformer.

[0020] (4) When the power electronic transformer is operating at high frequency, the winding loss and local temperature rise will increase with the frequency, current and load. The present invention arranges the liquid cooling structure near the winding stacked structure, which can respond to the changes in winding heat more quickly, reduce the resistance changes, parameter drift and efficiency reduction caused by temperature rise, thereby improving the stability of high frequency operation.

[0021] (5) The present invention does not require the direct processing of complex liquid cooling channels inside the conductive winding board. Instead, the embedded liquid cooling channel is set in a separate liquid cooling plate and then stacked with multiple conductive winding boards. This structure facilitates the separate manufacturing of winding boards and liquid cooling plates, reduces processing difficulty, and is conducive to adjusting the number of stacks and cooling configuration according to different power levels.

[0022] (6) In applications such as new energy grid connection, energy storage, electric vehicle charging, and DC power distribution, power electronic transformers often need to withstand high power and have a compact installation space. This invention enhances the internal heat dissipation capacity of the high-frequency isolation transformer through winding embedded liquid cooling, which can better meet the engineering requirements of high power density, miniaturization, and continuous operation.

[0023] Based on the above beneficial effects, this invention has good application prospects in the field of transformer technology. Attached Figure Description

[0024] Figure 1 This is a structural block diagram of a power electronic transformer.

[0025] Figure 2 This is a schematic diagram showing the positional relationship between a liquid cooling plate and a conductive winding plate.

[0026] Figure 3 This is a schematic diagram of a liquid cooling pipe in a liquid cooling plate.

[0027] Figure 4 This is a schematic diagram of liquid cooling pipes and magnetic heat-conducting sheets in another type of liquid cooling plate.

[0028] In the diagram: 1. Liquid cooling plate; 2. Conductive winding plate; 11. Liquid inlet; 12. Liquid outlet; 13. Liquid inlet main pipe; 14. Liquid outlet main pipe; 15. Parallel liquid cooling branch; 16. Magnetic heat-conducting sheet. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided with reference to the accompanying drawings and embodiments. Example 1

[0030] This embodiment provides a power electronic transformer with a winding-embedded liquid-cooling channel, such as... Figures 1 to 3 As shown, the power electronic transformer includes a power conversion module, a high-frequency isolation transformer, a cooling circulation module, and a control module. The input terminal of the power conversion module is connected to an input power supply, which can be an AC or DC input power supply with an input voltage of 380V to 10kV. The output terminal of the power conversion module is electrically connected to the primary side of the high-frequency isolation transformer to convert the input electrical energy into electrical energy suitable for high-frequency transmission by the high-frequency isolation transformer, with a high-frequency transmission frequency of 10kHz to 500kHz. The control module is electrically connected to the power conversion module and is used to control the on / off state, duty cycle, phase shift angle, or modulation mode of the switching devices in the power conversion module.

[0031] A high-frequency isolation transformer consists of a magnetic core, a primary winding, and a secondary winding. The magnetic core can be a ferrite core, a nanocrystalline core, or an amorphous core. The primary winding is electrically connected to the power conversion module, while the secondary winding is used to connect to the output terminal or load to achieve electrical isolation, voltage conversion, and power transfer of high-frequency electrical energy. The rated power of a high-frequency isolation transformer ranges from 5kW to 500kW.

[0032] like Figure 2As shown, the primary winding and / or secondary winding includes multiple conductive winding boards 2, which are PCB winding boards, copper foil winding boards, or laminated copper busbar winding boards. The thickness of the conductive winding board 2 is 0.1mm to 3mm; the width of the conductive path on the conductive winding board 2 is 2mm to 30mm; and the spacing between adjacent conductive paths is 0.5mm to 10mm. Multiple conductive winding boards 2 are stacked along the thickness direction, with 2 to 20 layers. An insulating layer with a thickness of 0.05mm to 2mm is provided between adjacent conductive winding boards 2 to ensure electrical insulation between them. A liquid cooling plate 1 is stacked with multiple conductive winding boards 2. The liquid cooling plate 1 is positioned between two adjacent conductive winding boards 2. The thickness of the liquid cooling plate 1 is 0.5mm to 8mm; the length of the liquid cooling plate 1 is 50mm to 500mm; and the width of the liquid cooling plate 1 is 30mm to 300mm. An insulating and thermally conductive layer is provided between the liquid cooling plate 1 and the conductive winding plate 2. The insulating and thermally conductive layer is a thermally conductive silicone sheet, a thermally conductive insulating adhesive layer, a thermally conductive epoxy layer, a ceramic insulating sheet, or a boron nitride-filled insulating composite layer. The thickness of the insulating and thermally conductive layer is 0.05 mm to 1 mm; the thermal conductivity of the insulating and thermally conductive layer is 1 W / (m·K) to 10 W / (m·K).

[0033] like Figure 3 As shown, the liquid cooling plate 1 has an embedded liquid cooling channel, and the liquid cooling plate 1 has a liquid inlet 11 and a liquid outlet 12. The liquid inlet 11 and the liquid outlet 12 are respectively located on opposite sides of the liquid cooling plate 1 to allow the coolant to flow along the plane of the liquid cooling plate 1. The inner diameter of the liquid inlet 11 and the liquid outlet 12 is 2mm to 20mm. Sealing joints, threaded joints, quick-connect joints, or welded joints are provided at the liquid inlet 11 and the liquid outlet 12 for connection with external liquid supply pipelines and return pipelines.

[0034] like Figure 3 As shown, the embedded liquid cooling channel includes an inlet manifold 13, an outlet manifold 14, and multiple parallel liquid cooling branches 15. The inlet port 11 is connected to the inlet manifold 13, and the outlet port 12 is connected to the outlet manifold 14. One end of each of the multiple parallel liquid cooling branches 15 is connected to the inlet manifold 13, and the other end is connected to the outlet manifold 14. The width of the inlet manifold 13 is 2mm to 20mm; the width of the outlet manifold 14 is 2mm to 20mm. The multiple parallel liquid cooling branches 15 are arranged at intervals along the width direction of the liquid cooling plate 1 and extend along the length direction of the liquid cooling plate 1. The number of parallel liquid cooling branches 15 is 4 to 20; the width of each parallel liquid cooling branch 15 is 0.5mm to 10mm; the depth of each parallel liquid cooling branch 15 is 0.2mm to 5mm; and the spacing between adjacent parallel liquid cooling branches 15 is 0.5mm to 8mm. A circular arc transition section can be provided at the connection between the parallel liquid cooling branch 15 and the inlet main pipe 13 and the outlet main pipe 14. The radius of the circular arc transition is 0.5mm to 10mm, so as to reduce local flow resistance and reduce bubble retention.

[0035] The liquid cooling plate 1 is made of an insulating and thermally conductive material, such as thermally conductive resin, boron nitride-filled resin, alumina ceramic, aluminum nitride ceramic, PEEK composite material, or PPS composite material. The liquid cooling plate 1 can also adopt a multi-layer composite structure, for example, including an upper cover plate and a lower base plate, with an inlet manifold 13, an outlet manifold 14, and multiple parallel liquid cooling branches 15 formed between the upper cover plate and the lower base plate. The upper cover plate and the lower base plate can be connected by bonding, hot pressing, welding, lamination, or sealing ring pressing to form a closed, embedded liquid cooling channel. A sealing edge with a width of 2mm to 15mm is provided on the outer periphery of the liquid cooling plate 1 to improve the pressure resistance and sealing reliability of the liquid cooling plate 1.

[0036] The embedded liquid cooling channel contains a coolant. The coolant can be one or more of the following: fluorinated liquid, silicone oil, synthetic ester insulating coolant, and mineral insulating oil. Preferably, the coolant is a low-conductivity insulating coolant with a conductivity less than 10 μS / cm, a breakdown voltage greater than 10 kV / mm, and a kinematic viscosity of 0.5 mm². 2 / s~100mm 2 / s. When the coolant flows in the parallel liquid cooling branch 15, it absorbs the heat transferred from the conductive winding plate 2 through the channel wall of the liquid cooling plate 1, and is discharged from the liquid cooling plate 1 through the outlet 12.

[0037] The cooling circulation module is connected to the liquid inlet 11 and outlet 12 of the liquid cooling plate 1. The cooling circulation module includes a liquid storage unit, a pumping unit, a heat exchange unit, a filtration unit, a flow regulation unit, a supply pipeline, and a return pipeline. The supply pipeline is connected to the liquid inlet 11, and the return pipeline is connected to the outlet 12. The coolant flow rate is 0.05 L / min to 10 L / min; the cooling circulation pressure is 0.02 MPa to 1 MPa; and the filtration accuracy of the filtration unit is 5 μm to 100 μm. Under the action of the pumping unit, the coolant enters the liquid cooling plate 1 through the liquid inlet 11, and is branched into multiple parallel liquid cooling branches 15 through the main inlet pipe 13. When flowing through the adjacent area of ​​the conductive winding plate 2, it absorbs heat, and then flows out from the outlet 12 after being merged through the main outlet pipe 14. After being cooled by the heat exchange unit, it is circulated again.

[0038] Furthermore, the control module is electrically connected to the cooling circulation module to control the coolant circulation status of the cooling circulation module. The control module can control the start / stop of the pumping unit, the speed adjustment unit, or the opening degree of the flow rate regulation unit based on temperature signals near the conductive winding plate 2, the liquid cooling plate 1, the inlet 11, or the outlet 12. For example, when the temperature of the conductive winding plate 2 or the liquid cooling plate 1 is higher than a preset threshold within the range of 60℃ to 90℃, the control module increases the coolant flow rate; when the temperature drops to a recovery threshold within the range of 40℃ to 70℃, the control module reduces the coolant flow rate to achieve on-demand cooling.

[0039] With the above structure, this embodiment stacks a liquid cooling plate 1 with multiple conductive winding plates 2, and forms an embedded liquid cooling channel within the liquid cooling plate 1, consisting of an inlet 11, a main inlet pipe 13, multiple parallel liquid cooling branches 15, a main outlet pipe 14, and an outlet 12, allowing the coolant to flow close to the heat-generating area of ​​the conductive winding plates 2. Compared with the traditional structure of air cooling or external heat dissipation from outside the high-frequency isolation transformer, this embodiment can shorten the heat transfer path between the conductive winding plates 2 and the coolant, improve the near-field heat dissipation efficiency of the windings, reduce the temperature rise of hot spots inside the stacked windings, and improve the temperature uniformity and operational reliability of the high-frequency isolation transformer under high power density operating conditions.

[0040] During assembly, the liquid cooling plate 1 is first tested for sealing to ensure that the inlet 11, outlet 12, inlet main pipe 13, outlet main pipe 14, and multiple parallel liquid cooling branches 15 are connected and leak-free. Then, multiple conductive winding plates 2 are stacked sequentially according to the predetermined electrical connection order of the primary winding and / or secondary winding, and an insulating and heat-conducting layer is laid between adjacent conductive winding plates 2 or between conductive winding plates 2 and liquid cooling plate 1, so that the liquid cooling plate 1 is located near the heating area of ​​the corresponding conductive winding plate 2. Subsequently, the liquid cooling plate 1 and multiple conductive winding plates 2 are aligned and pressed together along the thickness direction, so that the liquid cooling plate 1, conductive winding plates 2, and insulating and heat-conducting layer form a stacked winding assembly, and the lead-out ends of the conductive winding plates 2 face the power conversion module. The liquid cooling plate 1 extends out from one side of the block or output end, while the liquid inlet 11 and liquid outlet 12 of the liquid cooling plate 1 extend out towards the side that facilitates connection to the cooling circulation module; then the laminated winding assembly is installed into the core window or the outer periphery of the core column of the high-frequency isolation transformer, and the primary winding is electrically connected to the power conversion module, and the secondary winding is electrically connected to the output end or load; finally, the liquid inlet 11 is connected to the liquid supply pipeline of the cooling circulation module, the liquid outlet 12 is connected to the liquid return pipeline of the cooling circulation module, and the assembled liquid cooling plate 1 is tested for circulation again to confirm that the coolant can enter from the liquid inlet 11, be distributed to multiple parallel liquid cooling branches 15 through the liquid inlet main pipe 13, and then be collected by the liquid outlet main pipe 14 and discharged from the liquid outlet 12.

[0041] Furthermore, a pre-compressed thermally conductive pad layer is provided between the liquid cooling plate 1 and the conductive winding plate 2. The pre-compressed thermally conductive pad layer is one of the following: a thermally conductive silicone pad with insulating and elastic resilience, a ceramic-filled thermally conductive pad, a boron nitride-filled elastic thermally conductive sheet, or a thermally conductive insulating gel layer. During assembly, the pre-compressed thermally conductive pad layer is sandwiched between the liquid cooling plate 1 and the conductive winding plate 2, and is kept in a pre-compressed state by means of a pressure frame, screws, elastic clamping parts, or a laminated pressing structure. Since the surfaces of the conductive winding plate 2 and the liquid cooling plate 1 inevitably have micro-roughness, copper layer steps, or local flatness errors, the pre-compressed thermal conductive pad can undergo moderate elastic deformation after being compressed, filling the tiny gaps between them and reducing the interfacial air layer, thereby reducing the interfacial thermal resistance between the conductive winding plate 2 and the liquid cooling plate 1. At the same time, during the long-term operation of the high-frequency isolation transformer, even if the conductive winding plate 2, the liquid cooling plate 1, and the insulating material experience slight expansion differences due to thermal cycling or relaxation of assembly stress, the pre-compressed thermal conductive pad can maintain the bonding pressure through elastic rebound, avoiding the problem of local separation or increased contact thermal resistance between the liquid cooling plate 1 and the conductive winding plate 2, thereby improving the heat dissipation stability and long-term reliability of the near-field liquid cooling structure of the winding.

[0042] Furthermore, the liquid cooling plate 1 has a micro-arc-shaped pressing surface on the side facing the conductive winding plate 2. The micro-arc-shaped pressing surface is an arc-shaped or gently convex surface that slightly protrudes towards the conductive winding plate 2 along the thickness direction of the liquid cooling plate 1. During assembly, the liquid cooling plate 1 is laminated to the conductive winding plate layer 2 through an insulating and heat-conducting layer. The micro-arc-shaped pressing surface can preferentially contact the central area of ​​the conductive winding plate 2 during the pressing process, and gradually expand to both sides as the pressing force increases. This promotes the outward discharge of air between the liquid cooling plate 1 and the conductive winding plate 2, reducing interface bubbles, voids, and unbonded areas. Since heat usually accumulates more easily in the central area of ​​the laminated conductive winding plate 2, the micro-arc-shaped pressing surface can also provide a more stable contact pressure and a shorter heat transfer path in the central area, reducing the interfacial thermal resistance between the conductive winding plate 2 and the liquid cooling plate, and improving the heat absorption capacity of the liquid cooling plate for the hot spots in the central part of the winding. This further improves the temperature uniformity and long-term operational reliability of the high-frequency isolation transformer.

[0043] Furthermore, the liquid cooling plate 1 has a micro-pit, micro-groove, or micro-hole array on the side facing the conductive winding plate 2. These micro-pits, micro-grooves, or micro-hole arrays are distributed on the surface of the liquid cooling plate 1 in contact with the insulating and thermally conductive layer. During assembly, a thermally conductive insulating adhesive layer is coated or laid on the surface of the liquid cooling plate 1. Some of the thermally conductive insulating adhesive can enter the micro-pits, micro-grooves, or micro-hole arrays and form an embedded adhesive structure after curing or pressing. Thus, the microstructure on the surface of the liquid cooling plate 1 can exert a reverse locking and micro-adsorption effect on the thermally conductive insulating adhesive layer, improving the bonding strength between the thermally conductive insulating adhesive layer and the liquid cooling plate, and reducing interface slippage, debonding, and local voids caused by thermal cycling, vibration, or interlayer stress. Simultaneously, after being constrained by the microstructure, the thickness distribution of the thermally conductive insulating adhesive layer is more stable, which is beneficial for maintaining continuous adhesion between the liquid cooling plate 1 and the conductive winding plate 2, reducing interface thermal resistance, and thereby improving the heat dissipation reliability and long-term service stability of the near-field liquid cooling structure of the winding. Example 2

[0044] Based on Embodiment 1, the width of the parallel liquid cooling branch 15 located in the central region of the liquid cooling plate 1 is greater than the width of the parallel liquid cooling branch 15 located in the edge region of the liquid cooling plate 1. Specifically, the liquid cooling plate 1 can be divided into a central region and edge regions located on both sides of the central region along its width direction. The width of the central region can account for 30% to 70% of the total width of the liquid cooling plate 1. The width of the parallel liquid cooling branch 15 located in the central region is 2 mm to 8 mm, and the width of the parallel liquid cooling branch 15 located in the edge region is 0.8 mm to 5 mm. The width of the parallel liquid cooling branch 15 in the central region is 1.2 to 3 times the width of the parallel liquid cooling branch 15 in the edge region. The depth of the multiple parallel liquid cooling branches 15 is the same, for example, all are 0.5 mm to 2 mm; the spacing between adjacent parallel liquid cooling branches 15 is 1 mm to 5 mm. With the aforementioned width difference setting, after the coolant enters the main inlet pipe 13 from the inlet 11, it can be more easily distributed to the central parallel liquid cooling branch 15 with a larger flow cross-sectional area, and after flowing through the central region of the liquid cooling plate 1, it is collected by the outlet pipe 14 and discharged to the outlet 12, thereby enhancing the cooling capacity of the high-heat area in the central part of the conductive winding plate 2.

[0045] Preferably, the parallel liquid cooling branch 15 located in the middle region of the liquid cooling plate 1 has a wavy boundary. The wavy boundary is continuously or intermittently arranged along the extension direction of the parallel liquid cooling branch 15, so that the sidewall of the parallel liquid cooling branch 15 forms a periodic undulating structure. Since the width of the parallel liquid cooling branch 15 in the middle region is relatively large, the coolant is more likely to form a relatively stable boundary layer when flowing in the wide channel. By setting the wavy boundary, the heat transfer area of ​​the channel wall of the parallel liquid cooling branch 15 is increased, and the coolant generates lateral disturbance and local mixing during the flow process, thereby weakening the thermal boundary layer near the channel wall and improving the convective heat transfer efficiency between the coolant and the liquid cooling plate 1. As a result, the heat dissipation capacity of the middle region of the liquid cooling plate 1 to the high-heat area in the middle of the conductive winding plate 2 can be further enhanced, the temperature rise of the hot spot in the middle can be reduced, and the temperature uniformity of the laminated winding structure can be improved. Example 3

[0046] Based on Embodiment 2, a transverse branch is provided between two adjacent parallel liquid cooling branches 15, and the transverse branch is connected to each of the two adjacent parallel liquid cooling branches 15. Specifically, multiple parallel liquid cooling branches 15 are spaced apart along the width direction of the liquid cooling plate 1, and the transverse branch extends along the width direction of the liquid cooling plate 1 and forms a communication relationship with the two adjacent parallel liquid cooling branches 15, so that the coolant can perform local flow compensation between the adjacent parallel liquid cooling branches 15. Multiple transverse branches are spaced apart along the length direction of the parallel liquid cooling branches 15, and the distance between two adjacent transverse branches is 10mm to 80mm; the width of the transverse branch is 0.3mm to 5mm; the depth of the transverse branch is 0.2mm to 3mm; the width of the transverse branch is less than the width of the parallel liquid cooling branch 15, for example, 20% to 80% of the width of the parallel liquid cooling branch 15. A circular arc transition section with a radius of 0.3 mm to 5 mm is provided at the connection between the transverse branch and the parallel liquid cooling branch 15 to reduce local flow resistance and reduce bubble retention. By setting the transverse branch, when the flow rate of a certain parallel liquid cooling branch 15 decreases due to increased local flow resistance, bubble retention, or impurity deposition, the coolant can be replenished from the adjacent parallel liquid cooling branch 15 through the transverse branch, thereby improving the flow balance among the parallel liquid cooling branches 15 within the liquid cooling plate 1. Example 4

[0047] Based on Example 3, such as Figure 4As shown, a plurality of spaced magnetic heat-conducting sheets 16 are provided on the outer side of the liquid cooling plate 1. The magnetic heat-conducting sheets 16 are located on the side of the liquid cooling plate 1 away from the conductive winding plate 2, or in the outer peripheral side area of ​​the liquid cooling plate 1. The plurality of magnetic heat-conducting sheets 16 are arranged at intervals along the length and / or width direction of the liquid cooling plate 1, and a non-magnetic space 17 is formed between two adjacent magnetic heat-conducting sheets 16 to avoid the magnetic heat-conducting sheets 16 forming a continuous whole structure. The magnetic heat-conducting sheets 16 are connected to the liquid cooling plate 1 through a thermally conductive insulating adhesive layer 18. The thermally conductive insulating adhesive layer 18 is used both to achieve the bonding and fixation between the magnetic heat-conducting sheets 16 and the liquid cooling plate 1, and to form an insulating thermally conductive path between the two.

[0048] The magnetic heat-conducting sheet 16 is a rectangular, strip-shaped, or arc-shaped sheet structure with a length of 10mm to 100mm, a width of 3mm to 40mm, and a thickness of 0.2mm to 5mm. The spacing between two adjacent magnetic heat-conducting sheets 16 is 1mm to 20mm; the distance between the magnetic heat-conducting sheet 16 and the edge of the liquid cooling plate 1 is 1mm to 15mm. The thickness of the thermally conductive insulating adhesive layer is 0.02mm to 1mm; the thermal conductivity of the thermally conductive insulating adhesive layer is 1W / (m·K) to 8W / (m·K); and its breakdown strength is not less than 5kV / mm.

[0049] The magnetic heat-conducting sheet 16 is made of one or more of ferrite sheets, nanocrystalline magnetic sheets, or amorphous magnetic sheets. Preferably, the magnetic heat-conducting sheet 16 is made of ferrite sheets, which have high resistivity and low high-frequency eddy current losses, making them suitable for placement on the outside of the windings of a high-frequency isolation transformer or on the outside of the liquid cooling plate 1. In another embodiment, the magnetic heat-conducting sheet 16 may also be made of segmented nanocrystalline magnetic sheets or segmented amorphous magnetic sheets, with adjacent sheets separated by non-magnetic spacing. The magnetic heat-conducting sheet 16 is preferably disposed outside the main magnetic flux path of the magnetic core, used for local guidance and constraint of the leakage magnetic field around the liquid cooling plate 1, rather than serving as a closed path for the main magnetic flux of the magnetic core.

[0050] Through the above structure, the magnetic heat-conducting sheet 16 can form a local low magnetic resistance region on the outside of the liquid cooling plate 1, so that part of the leakage magnetic field around the liquid cooling plate 1 or on the outside of the conductive winding plate 2 is preferentially distributed along the magnetic heat-conducting sheet 16, reducing the risk of leakage magnetic field spreading to the external space and causing additional losses through the surrounding conductive structure. On the other hand, the magnetic heat-conducting sheet 16 is attached to the liquid cooling plate 1 through the thermally conductive insulating adhesive layer, which can diffuse and assist in the conduction of local heat in the liquid cooling plate 1. Since multiple magnetic heat-conducting sheets 16 are arranged at intervals, the shunting effect of continuous magnetic sheets on the main magnetic flux path can be reduced, and the additional losses and local thermal stress concentration under high-frequency alternating fields can be reduced.

[0051] In one embodiment, the outer peripheral edge of the liquid cooling plate 1 is provided with an embedding groove, and the magnetic heat-conducting sheet 16 is at least partially embedded in the embedding groove and connected to the liquid cooling plate 1 through a thermally conductive insulating adhesive layer. The embedding groove can be spaced apart along the length or width direction of the liquid cooling plate 1, and multiple magnetic heat-conducting sheets 16 are respectively embedded in the corresponding embedding groove, forming a non-magnetic gap between two adjacent magnetic heat-conducting sheets 16. By embedding the magnetic heat-conducting sheet 16 into the edge region of the liquid cooling plate 1, the positioning accuracy and fixing reliability of the magnetic heat-conducting sheet 16 are improved, making it stably located in the edge region of the outer side of the liquid cooling plate 1 where leakage magnetic field is more easily diffused; at the same time, the embedded arrangement can also increase the contact area between the magnetic heat-conducting sheet 16 and the liquid cooling plate 1, reduce the interface thermal resistance, and enable the magnetic heat-conducting sheet 16 to more effectively diffuse the heat in the edge region of the liquid cooling plate 1 while confining the leakage magnetic field.

[0052] Preferably, segmented ferromagnetic strips are provided between two adjacent parallel liquid cooling branches 15 of the liquid cooling plate 1. The segmented ferromagnetic strips are arranged at intervals along the extension direction of the parallel liquid cooling branches 15 and embedded in the solid area of ​​the liquid cooling plate 1, forming a non-magnetic space between two adjacent segmented ferromagnetic strips. The segmented ferromagnetic strips can be one or more of ferrite strips, insulating coated soft magnetic strips, nanocrystalline magnetic strips, or amorphous magnetic strips. By setting segmented ferromagnetic strips, a local low magnetic resistance region is formed in the liquid cooling plate 1, which guides and confines the leakage magnetic field near the liquid cooling plate 1, reducing the outward diffusion of the leakage magnetic field. At the same time, the segmented ferromagnetic strips can also serve as an auxiliary heat conduction and local reinforcement structure for the liquid cooling plate 1, promoting heat dissipation between adjacent parallel liquid cooling branches 15 and improving the structural stability of the liquid cooling plate 1. Since the segmented ferromagnetic strips are arranged at intervals, the risk of additional losses generated by the continuous ferromagnetic structure under high-frequency alternating magnetic field can be reduced, and its influence on the main magnetic flux path of the magnetic core can be reduced. Example 5

[0053] Based on the above embodiments, the pumping unit is a miniature diaphragm pump, gear pump, centrifugal pump, plunger pump, or brushless DC water pump, preferably an adjustable-speed miniature pump. The control module is electrically connected to the pumping unit and outputs pulse control signals to it, causing the pumping unit to intermittently increase or decrease its output flow rate according to a preset pulse cycle, thereby creating a periodically changing coolant flow rate within the embedded liquid cooling channel. The pulse supply method can be start-stop pulse supply, speed-modulated pulse supply, or valve-controlled pulse supply; where start-stop pulse supply refers to the control module controlling the pumping unit to periodically start and stop according to a preset frequency; speed-modulated pulse supply refers to the control module controlling the pumping unit to periodically switch between high and low speeds; and valve-controlled pulse supply refers to the pumping unit maintaining a basic output state and periodically changing the flow cross-sectional area through a flow regulation unit to create flow pulsations.

[0054] In one specific embodiment, the control module controls the pumping unit to operate in a speed-modulated pulsed cooling mode. The pumping unit periodically switches between a low-flow state and a high-flow state. The coolant flow rate in the low-flow state is 0.05 L / min to 1 L / min; the coolant flow rate in the high-flow state is 0.2 L / min to 5 L / min. The pulsed cooling frequency is 0.05 Hz to 20 Hz; the duty cycle of the high-flow state within a single pulse cycle is 10% to 90%. By periodically changing the coolant flow rate between the low-flow and high-flow states, the scouring effect of the coolant on the inner walls of the inlet manifold 13, the parallel liquid-cooled branch 15, and the outlet manifold 14 is enhanced.

[0055] In another specific embodiment, the control module adjusts the pulse liquid supply parameters based on the temperature signal of the conductive winding plate 2 or the liquid cooling plate 1. Specifically, temperature sensors are installed at the conductive winding plate 2, the liquid cooling plate 1, the liquid inlet 11, the liquid outlet 12, and the liquid supply or return pipeline, and the control module receives the detection signals from the temperature sensors. When the temperature of the conductive winding plate 2 or the liquid cooling plate 1 is lower than a first temperature threshold, the pumping unit operates in a continuous low-flow mode; when the temperature of the conductive winding plate 2 or the liquid cooling plate 1 reaches or exceeds the first temperature threshold, the control module controls the pumping unit to enter a pulse liquid supply mode; when the temperature reaches or exceeds a second temperature threshold, the control module increases the pulse liquid supply frequency, increases the flow rate in the high-flow state, or increases the duty cycle in the high-flow state. The first temperature threshold is 50℃~80℃; the second temperature threshold is 70℃~110℃.

[0056] Furthermore, the control module can also adjust the pulse supply mode based on the temperature difference between the inlet 11 and the outlet 12. For example, when the temperature difference between the coolant at the outlet 12 and the coolant at the inlet 11 is greater than 5°C to 25°C, the control module increases the duration of the high-flow state of the pumping unit or increases the pulse frequency to enhance the heat exchange and renewal capacity of the coolant in the embedded liquid cooling channel; when the temperature difference is lower than the preset recovery value, the control module reduces the pulse frequency or reduces the duty cycle of the high-flow state to reduce pumping energy consumption.

[0057] Furthermore, to prevent excessive pressure inside the liquid cooling plate 1 caused by pulsed liquid supply, the cooling circulation module can also be equipped with a pressure sensor or a pressure relief unit. The pressure sensor is located near the liquid supply line, inlet 11, or main inlet pipe 13 to detect the liquid supply pressure of the embedded liquid cooling channel. When the liquid supply pressure exceeds a preset pressure threshold, the control module reduces the pulse amplitude of the pumping unit, reduces the flow rate during high flow conditions, or suspends pulsed liquid supply. The preset pressure threshold is 0.1 MPa to 1 MPa. Through the above pressure limitation, the sealing safety of the main inlet pipe 13, the parallel liquid cooling branch 15, the main outlet pipe 14, and the liquid cooling plate 1 can be guaranteed.

[0058] Furthermore, the pulsed liquid supply method is used in conjunction with multiple parallel liquid cooling branches 15. Due to the difference in flow resistance among the multiple parallel liquid cooling branches 15, the periodic pressure wave generated by the pulsed liquid supply can promote the redistribution of coolant within the main inlet pipe 13 and enhance the flow disturbance within each parallel liquid cooling branch 15. When a transverse branch is provided between adjacent parallel liquid cooling branches 15, the instantaneous pressure difference generated by the pulsed liquid supply can also cause the coolant to undergo local flow compensation between adjacent parallel liquid cooling branches 15 via the transverse branch, thereby improving the uniformity of flow distribution within the liquid cooling plate 1.

[0059] Through the above structure and control method, the pumping unit supplies coolant to the embedded liquid cooling channel in a pulsed liquid supply manner, so that the coolant forms a periodic flow rate change in the inlet manifold 13, multiple parallel liquid cooling branches 15 and the outlet manifold 14. This can weaken the stable thermal boundary layer near the channel wall and improve the convective heat transfer efficiency between the coolant and the liquid cooling plate 1. At the same time, the pulsed liquid supply can also reduce the risk of bubble retention and microparticle deposition in the parallel liquid cooling branches 15, reduce the impact of local blockage or insufficient flow on the heat dissipation effect of the conductive winding plate 2, and thus further improve the heat dissipation efficiency and reliability of the power electronic transformer under high frequency and high power density operating conditions.

[0060] In summary, this invention addresses the challenge of heat dissipation within the windings of power electronic transformers operating at high frequencies and high power densities. It proposes a structural solution with an embedded liquid-cooling channel. This solution involves stacking a liquid-cooling plate 1 with multiple conductive winding plates 2, forming an embedded liquid-cooling channel within the liquid-cooling plate 1. This channel consists of an inlet 11, a main inlet pipe 13, parallel liquid-cooling branches 15, a main outlet pipe 14, and an outlet 12. This allows the coolant to flow directly close to the main heat-generating areas of the primary and / or secondary windings, shortening the heat transfer path between the conductive winding plates and the cooling medium, and improving near-field heat dissipation efficiency. This solution employs a separate, stacked structure for the insulating coolant and the liquid-cooling plate, achieving efficient heat dissipation without significantly altering the current path of the conductive winding plates, while also considering electrical insulation, structural assembly, and cooling reliability. Furthermore, the design incorporates parallel liquid-cooling branches, branches with varying widths, lateral branches, magnetic heat-conducting sheets, and pulsed liquid supply to improve flow distribution, reduce localized hot spots, constrain leakage flux, and enhance heat exchange capacity. Therefore, this invention can improve the temperature uniformity, operational stability and long-term reliability of high-frequency isolation transformers, and is suitable for engineering application scenarios with high requirements for compactness, high efficiency and high reliability, such as new energy grid connection, energy storage systems, electric vehicle charging, DC power distribution, rail transit and industrial power supply.

[0061] The winding-embedded liquid-cooled structure of this application is suitable for high-frequency isolation transformers employing planar windings, copper foil windings, PCB winding boards, or laminated conductive winding boards. For planar transformers with a magnetic core column, the stacked conductive winding plate and liquid cooling plate can be integrally set on the outer periphery of the magnetic core column, so that the magnetic core column forms magnetic coupling with the primary and secondary windings. For transformers where the magnetic core does not penetrate the winding assembly, the liquid cooling plate and conductive winding plate can be set as sheet-like stacked winding assemblies in the coupling area inside the magnetic core window, on the side of the magnetic core, or on the outer periphery of the magnetic core. For high-frequency transformers without a magnetic core or with weak magnetic core coupling, the liquid cooling plate can also be stacked with the planar windings of the primary and / or secondary sides for near-field cooling of winding losses generated by high-frequency and high-current. In addition, for side-coupled structures, such as transformers where the magnetic field direction is basically parallel to the plane where the planar winding is located, the stacked winding assembly can be arranged along the lateral magnetic field coupling area, so that the primary and secondary windings form a coupling relationship with the lateral magnetic field, while the liquid cooling plate is sandwiched or attached between the conductive winding plates to shorten the heat transfer path between the windings and the coolant. This application can arrange the laminated winding assembly consisting of the liquid cooling plate and the conductive winding plate on the outer periphery of the core column, inside the core window, on the side of the core, on the outer periphery of the core, in the core part of the extended area, or in the non-core coupling area, depending on the coupling method between the core and the winding, so as to adapt to the winding heat dissipation requirements of different types of high-frequency transformers.

[0062] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A power electronic transformer with an embedded liquid-cooled winding channel, comprising a power conversion module, a high-frequency isolation transformer, and a control module, wherein the input terminal of the power conversion module is connected to an input power supply, and the output terminal of the power conversion module is electrically connected to the primary side of the high-frequency isolation transformer, the power conversion module being used to convert input electrical energy into electrical energy suitable for high-frequency transmission by the high-frequency isolation transformer; the high-frequency isolation transformer comprising a magnetic core, a primary winding, and a secondary winding, the primary winding being electrically connected to the power conversion module, and the secondary winding being used to connect to the output terminal or a load; the control module being used to control the electrical energy conversion process of the power conversion module, characterized in that: The primary winding and / or the secondary winding includes multiple conductive winding plates. The high-frequency isolation transformer also includes a liquid cooling plate and an embedded liquid cooling channel disposed within the liquid cooling plate. The liquid cooling plate and the multiple conductive winding plates are stacked together, and the embedded liquid cooling channel is provided with coolant.

2. The power electronic transformer with winding embedded liquid cooling channel as described in claim 1, characterized in that: The coolant is one or more of the following: fluorinated liquid, silicone oil, synthetic ester insulating coolant, and mineral insulating oil.

3. The power electronic transformer with winding embedded liquid cooling channel as described in claim 1, characterized in that: It also includes a cooling circulation module, which is connected to the inlet and outlet of the embedded liquid cooling channel.

4. The power electronic transformer with winding embedded liquid cooling channel as described in claim 3, characterized in that: The control module is also electrically connected to the cooling circulation module and is used to control the coolant circulation state of the cooling circulation module.

5. The power electronic transformer with winding embedded liquid cooling channel as described in claim 1, characterized in that: The liquid cooling plate is provided with a liquid inlet and a liquid outlet. The embedded liquid cooling channel includes a liquid inlet main pipe connected to the liquid inlet, a liquid outlet main pipe connected to the liquid outlet, and multiple parallel liquid cooling branches. One end of each of the multiple parallel liquid cooling branches is connected to the liquid inlet main pipe, and the other end is connected to the liquid outlet main pipe.

6. The power electronic transformer with winding embedded liquid cooling channel as described in claim 5, characterized in that: Along the width direction of the liquid cooling plate, the width of the parallel liquid cooling branch located in the central region is greater than the width of the parallel liquid cooling branch located in the edge region.

7. The power electronic transformer with winding embedded liquid cooling channel as described in claim 5, characterized in that: A transverse branch is provided between two adjacent parallel liquid cooling branches, and the transverse branch is connected to the two adjacent parallel liquid cooling branches respectively.

8. The power electronic transformer with winding embedded liquid cooling channel as described in claim 1, characterized in that: The outer side of the liquid cooling plate is provided with spaced magnetic heat-conducting sheets.

9. The power electronic transformer with winding embedded liquid cooling channel as described in claim 8, characterized in that: The material of the magnetic heat-conducting sheet is one or more of ferrite sheets, nanocrystalline magnetic sheets, or amorphous magnetic sheets.

10. The power electronic transformer with winding-embedded liquid-cooled channels as described in any one of claims 1-9, characterized in that: The cooling circulation module includes a pumping unit, and the control module is used to control the pumping unit to supply coolant to the embedded liquid cooling channel in a pulsed liquid supply manner.

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