Liquid / fluid cooling system for high power density (HPD) transformers

Abstract

We provide liquid-cooled thermal management solutions to improve volumetric power density for pulse load power converters and other applications where space is constrained. [Solution] A power converter using a liquid cooling system to cool a liquid-cooled transformer 100, wherein the coils 135 of the transformer 120 are in physical / thermal contact with a cold plate 160 embedded in a thermally conductive solid (epoxy or resin) and sandwiched between the coils and / or in contact with the outer surface of the coils. In addition / or, the cold plate may also be in physical / thermal contact with the transformer core. A cooling fluid is supplied so as to flow through the cold plate. In another embodiment, the transformer is immersed in a cooling fluid such as oil in a thermally controlled housing that houses the coils. The cold plate is in physical / thermal contact with the housing. The cooling fluid supplied into the cold plate conducts heat from the oil-surrounded transformer.

Description

Technical Field

[0001] This application relates generally to cooling systems and high-power electronic power systems, and more particularly to high-power density (HPD) transformers in high-power electronic power systems. This application further relates to a liquid cooling system for HPD transformers.

Background Art

[0002] Transformer Overview A transformer is a passive electrical device that transfers electrical energy from a power source to a load without transferring current between one electrical circuit (the "power source") and one or more other electrical circuits (the "loads"). Energy is transmitted solely by electric field transfer. A transformer has two or more independent wire coils, each typically wound around one or more iron (magnetic) metal cores. When the current flowing through any one of the power coils of the transformer changes, a changing magnetic field (magnetic flux) is generated, inducing a changing electromotive force in any other load coil wound around the same core. If the load coil is connected to an electrical load, current flows through the load coil. Electrical energy can be transferred (presumably between a number of) coils without a conductive metal connection between the power circuit and the load circuit. Thus, the power source current and the load current can be physically completely separated.

[0003] Transformers are used in power applications to increase the alternating voltage at low current (step-up transformer) or decrease the alternating voltage at high current (step-down transformer).

[0004] Overview of High-Power Systems Medium to high-power systems can supply power to large industrial plants, factories, large transportation vehicles (such as large ships and aircraft), office buildings, apartment buildings or entire cities. A power conversion system or power converter converts power in medium to high-power electronic distributed power buses and grids, for example, converting from high voltage to low voltage, from low voltage to high voltage, converting the current from one alternating frequency to another, or converting from direct current to alternating current or from alternating current to direct current.

[0005] A power system generally consists of generation, transmission, distribution, and end-use. Electricity is supplied by one or more generators or by renewable energy systems such as solar power. Along the path to the final load (the device that uses the electricity), the electricity is typically received and transmitted by one or more power converters. For example, a converter on the generator side can receive alternating current (AC) power from the generator via a stator bus and convert the AC power to an appropriate output frequency, such as the grid frequency. The AC power is then supplied to the power grid via a line bus.

[0006] Low voltage, medium voltage, and high voltage are not defined in a single, unambiguous way. For example, "low voltage" may refer to voltages of 1.5kV or less, "medium voltage" may refer to voltages between 1.5kV and 100kV, and "high voltage" may refer to voltages of 100kV or more.

[0007] High Power Density (HPD) Power Systems - Power Converters for Ships and Other Environments Where Compact Space Design is Required In certain environments, such as military and commercial vessels and aircraft, efficient use of space is crucial. Therefore, ships require smaller power converters than those used in land-based environments. Furthermore, weight reduction is desirable for power conversion systems used in marine applications. Reducing the volume and weight of power converters leads to improved power density and reduced ship drag.

[0008] This system and method are, but are not limited to, particularly well suited to microgrids such as those found in ships and aircraft. (Grids and microgrids are generally referred to as “power systems” in this specification). Power systems for ships and aircraft, as well as other power systems suitable for compact physical spaces, have the advantage of being as small and compact as possible physically. At a given power level, the smaller the physical size, the higher the power density of the entire power system. However, high power density generates a large amount of heat, which needs to be dissipated.

[0009] An example of a high power density (HPD) system is a power electronics building block (PEBB) minimum compatible unit (LRU), which is a power converter structure and functional element, and may also be a power processor that converts any input power into an output of a desired voltage, current, and frequency. PEBBs are typically intended for use as part of a modular and scalable power converter architecture using multiple interconnected PEBBs.

[0010] PEBBs typically consist of power devices, gate drives, transformers, and other components integrated into a building block with configurable and clearly defined functions.

[0011] From the perspective of energy efficiency and effective use of onboard space, there is a need for a PEBB LRU that is equipped with small elements, has high power density, and generates a large amount of heat. Such PEBB LRUs and other small, high-power systems are physically compact and may require the use of transformers to step up low voltage to high voltage. Such high-power transformers may require the use of a 1:1 winding ratio or a K:N winding ratio (where N is the same as or greater than K). Smaller volumes are particularly prone to heat dissipation, and higher winding ratios generate even more heat, requiring corresponding heat dissipation.

[0012] Overview of heat dissipation The power handling limits of power converters and power electronics building blocks (PEBBs) for power converters are largely determined by the thermal management of the high-frequency transformers used in such systems. "Thermal management" is another way of saying the heat dissipation capacity of the transformer, which greatly affects the transformer's volume and weight, and consequently, the power density and specific power of the power converter.

[0013] Conventional power converters and power electronics building blocks (PEBBs) relied on air-cooled transformers. The heat generated from the transformer during the operation of the power converter was absorbed by the I of the primary and secondary coils. 2It consists of t-loss (coil loss) and thermal / power loss in the magnetic core (core loss).

[0014] The thermal loss distribution of coil losses and core losses varies depending on the specific design and materials used. Typical transformer cooling systems are air-cooled and include, for example, fans that circulate air around and inside the transformer. This requires sufficient space and high air velocity for airflow, but these can both be counterproductive to the goal of keeping the overall volume of the power converter low.

[0015] In light of the aforementioned shortcomings, such as the challenges of volumetric power density, there is a need for compact cooling systems for medium to high voltage HPD transformers. Furthermore, there is a need for cooling systems that utilize liquid cooling for efficient heat transfer. In addition, there is a need for cooling systems that allow for structural integration with the power transformer, or cooling systems that provide a large contact area between one or more liquid coolants and the electrically active heat-generating elements of the power transformer. [Prior art documents] [Patent Documents]

[0016] [Patent Document 1] U.S. Patent Application Publication No. 2012 / 0092108 [Overview of the project]

[0017] This system and method advances air-cooled converters with a liquid-cooled thermal management solution to provide improved volumetric power density, particularly for applications such as pulse-load power converters in space-constrained environments, including, but not limited to, military or commercial vessels or aircraft cabins.

[0018] Liquids and fluids In general / ordinary usage, the terms "liquid" and "fluid" are generally or approximately synonymous. In chemistry and physics, a "fluid" is something that flows (including both liquids and gases), while a "liquid" is a substantially incompressible fluid that conforms to the shape of its container but maintains (approximately) a constant volume regardless of pressure. In this specification, both the terms "liquid" and "fluid" refer" refer to a substantially incompressible substance that is fluid and has a substantially constant volume. (That is, both terms broadly mean "a fluid that is liquid but not gas"). However, in this specification, the terms "liquid" and "fluid" are given further distinct meanings. (A) "Liquid" refers to the coolant material 240 (see FIG. 2) (which is water in some embodiments) that is flowed through the cold plate 160 (see FIG. 1). (B) "Fluid" refers to the heat-conducting liquid material 740 (see FIG. 7) (which is oil in some embodiments) for use in direct contact with the transformer 120 within the thermal management housing 710.

[0019] The semantics of "liquid" 240 (e.g., water) and "fluid" 740 (e.g., oil) are merely for convenience of understanding in order to distinguish different types / usages of various liquids that provide cooling and / or transfer and remove heat.

[0020] In this specification, the consistent use of "coolant" and "heat transfer" according to the context is also for convenience of understanding. In other documents in the relevant technical field, terms such as "coolant" or "heat transfer substance" may be used synonymously or may be used with different meanings.

[0021] The advantageous designs of the embodiments of the present invention are obtained from the independent claims, the dependent claims, the specification, and the drawings. Hereinafter, preferred examples of the embodiments of the present invention will be described in detail with reference to the accompanying drawings. The drawings are incorporated herein and form a part of the content of this specification, illustrate the present invention, and also serve to explain the principles of the present invention in conjunction with the detailed description of the invention so that those skilled in the art can implement the present invention.

Brief Description of the Drawings

[0022] [Figure 1] FIG. is a diagram showing an exemplary transformer with an integrated cold plate according to an embodiment of the present system and method. [Figure 2] FIG. is a diagram showing an exemplary liquid cooling system according to an embodiment of the present system and method. [Figure 3A] FIG. is a diagram showing an exemplary transformer with an integrated cold plate according to an embodiment of the present system and method. [Figure 3B] FIG. is a diagram showing an exemplary transformer with an integrated cold plate according to an embodiment of the present system and method. [Figure 4] FIG. is a diagram showing an exemplary transformer with an integrated cold plate according to an embodiment of the present system and method. [Figure 5] FIG. is a diagram showing an exemplary power converter including a plurality of power electronics building blocks, each power electronics building block having an exemplary liquid cooling system. [Figure 6A] FIG. is a diagram showing an exemplary transformer coil according to the present system and method. [Figure 6B] FIG. is a diagram showing an exemplary transformer coil according to the present system and method. [Figure 7] FIG. is a diagram showing some components of an exemplary fluid-immersed transformer according to an embodiment of the present system and method. [Figure 8] FIG. is a diagram showing some components of an exemplary fluid-immersed transformer according to an embodiment of the present system and method. [Figure 9] FIG. is a diagram showing an exemplary use of a liquid or fluid-cooled transformer integrated into a hybrid power electronics building block that can be used in a power converter.

[0023] Regarding the explanations in the drawings The descriptions in the drawings are for convenience to help understand and to remind us of the properties of certain components. These descriptions should not be interpreted restrictively, as various components may be known or understood by additional or alternative notations, names, or embodiments, as described herein. For further details regarding the components shown in the drawings, please refer to the reference numerals in the drawings, the explanations of those reference numerals in the detailed description of the invention, and the explanations of where reference numerals are omitted in the detailed description of the invention.

[0024] Specific functions or operating values ​​(e.g., voltage values, power values, structural dimensions, and other numerical values) shown in the drawings are illustrative only and should not be interpreted restrictively unless otherwise stated herein. [Modes for carrying out the invention]

[0025] This specification describes the present invention with exemplary embodiments for specific applications, but the invention is not limited thereto.

[0026] The following detailed description is illustrative and does not limit the taught systems, configurations, and methods, nor the components or steps of the taught systems, configurations, and methods, nor the uses of the systems, methods, and configurations disclosed herein. Furthermore, it is not bound by, nor is the technical scope limited by, the theories presented in the background art and summary sections above, or in the following detailed description. To those skilled in the art who have read the teachings herein, additional modifications, uses, and embodiments within the technical scope, as well as additional fields in which the invention has significant utility, will be apparent.

[0027] Throughout this application, the expression “includes” is used in descriptions of various embodiments, meaning that the system and method includes the specific components or steps described, which may include other components or steps not described, described in relation to other embodiments, shown only in the drawings, or known in the art as necessary for the function of a power system. However, it will be apparent to those skilled in the art that in some specific examples, embodiments may be described using the expression “basically consists of” or “consistes of.”

[0028] This instruction is not intended to limit its scope, but rather to deepen understanding of it. It will be clear to those skilled in the art that even singular nouns, unless otherwise specified, include plural nouns. Therefore, singular articles and "at least one" are interchangeable in this application.

[0029] The headings used in the detailed description of the invention are for readability purposes only and should not be construed as definitions or limitations.

[0030] The System and Method are not limited to the embodiments described below, which are merely illustrative. The entire scope of the System and Method is described in the following claims. The attached claims constitute a disclosure in themselves, and the entire scope of the System and Method may include only the components described in the claims.

[0031] Exemplary liquid cooling elements and liquid cooling systems for transformers It will be obvious to those skilled in the art that the effective operation of electrical systems requires heat dissipation, including the heat dissipation of transformers. Conventional power converters use air cooling, such as cooling fans or the general airflow of the surrounding environment, sometimes supplemented by vents and heat sinks.

[0032] As described above, new power converters for compact environments may have significantly increased high power density (HPD) and specific power (compared to the power density / specific power of conventional power converters). This increase in power density and specific power generates more volumetric heat or gravimetric heat (i.e., heat per unit volume or unit weight) and higher temperatures than conventional power converters. Furthermore, such systems may utilize HPD transformers 120 to convert current to high frequency (HF), which further increases heat generation.

[0033] To dissipate the heat generated in the HPD-HF transformer in the HPD converter, a liquid cooling system can be used on the HPD transformer 120 in combination with air cooling, or to substantially replace the air cooling of the transformer 120.

[0034] In particular, the combination of the high voltage of the HPD power converter, multiple transformer windings, and compressed size can lead to significant heat generation from the HPD-HF transformer 120 as a whole. The heat generated from the HPD-HF transformer 120 during operation can cause I2 in the primary and secondary coils. 2 t loss (current squared (I 2 This consists of time loss (coil loss) and heat / power loss in the magnetic core of the transformer 120 (core loss).

[0035] In some embodiments, the system and method introduce dedicated liquid cooling for the HPD-HF transformer 120.

[0036] For example, in some embodiments, the system advances air cooling with a liquid-cooled thermal management solution to further improve volumetric power density, particularly for space-constrained pulse load converter applications (e.g., on board military or commercial vessels or in aircraft). The thermal loss distribution of coil losses and core losses varies depending on the specific design and materials used. To reduce volume and increase power density, embodiments of the system and method utilize a liquid-cooled HPD-HF transformer 100, which includes a liquid cooling solution for thermal management of transformer coil components 135.2, 135.1 and transformer core 145.

[0037] Exemplary HPD-HF transformer with integrated cold plate Figure 1 is a schematic diagram of an exemplary HPD-HF transformer 120 equipped with an integrated cold plate 160 of a liquid cooling system 200 (see Figure 2) according to one embodiment of the system and method (in Figure 1, the composite transformer 120 itself (coil + magnetic core) (hereinafter referred to as "TICP") equipped with the integrated cold plate 160 is denoted by reference numeral 100.1). In one embodiment, the TICP forms a structurally integrated unit, in other words, several components 160, 165 of the liquid cooling system 200 are embedded within the structure of the HPD-HF transformer 120.

[0038] Coil components (coils) and cores In one embodiment, the HPD-HF transformer 120 includes one or more primary (high voltage / HV) coil components 135.1, one or more secondary (low voltage / LV) coil components 135.2, one or more magnetic (iron) cores 145 (three shown in the figure) and electrical connections 185 (only one shown in the figure). One or more of the cores 145 may have one or more internal core elements 147 that pass through the gaps or spaces of the coils 135 and / or the gaps of the cold plate 160. One or more internal core elements 147 may be solely for structural support or may be made of iron material to provide additional magnetic coupling / inductance between the coils 135.

[0039] The metallic conductive elements 610 of the primary coil 135.1 and secondary coil 135.2 are not shown in Figure 1 (see Figures 6A and 6B instead), but are shown as the outer surfaces of solid coil components 135.1, 135.2, which can be made from, for example, silicon, resin, epoxy, ceramic, glass or other non-conductive substances or materials 620.1, 620.2 (see Figures 6A and 6B for a cross-sectional view of coil 135), in which the conductive (typically metallic) coil 610 is embedded. For the sake of brevity, in this specification, “coil component” 135 is typically abbreviated to simply “coil” 135. In one exemplary embodiment, the coil wire 610 may be Litz wire.

[0040] Adhesive / enclosure materials such as epoxy, resin, glass, and ceramic materials are generally called "coil support materials" 620.1, 620.2 and are effective heat transfer materials. Heat generated in the conductive elements (wire, filament, or foil, etc.) 610 of the coil 135 is easily transferred to the epoxy, resin, or ceramic material 620.1, 620.2 surrounding the coil components 135.1, 135.2.

[0041] In the exemplary embodiment shown in the figure, three cold plates 160 (also called “heat exchange plates” 160) are physically inserted or sandwiched between all of the coil components 135.1, 135.2 and the core 145, and are in substantial contact with them. In one embodiment, the cold plates are made of a non-ferrous (non-magnetic) metal. In another embodiment, the cold plates 160 may be manufactured from other non-ferrous, non-metallic materials suitable for heat transfer.

[0042] Penetrating each cold plate 160 are one or more internal liquid transport channels 260 (or "coolant channels" 260) (not shown in Figure 1, see Figure 2) suitable for guiding a coolant 240 (see Figure 2), such as deionized water, chilled water, treated water with or without petrochemical additives, or other coolants 240.

[0043] Two or more coolant tubes 165 (or "coolant conduits" 165) are connected to the cold plate 160 at coolant ports 175, which are fluid input / output ports along the outer surface of the cold plate 160. The coolant ports 175 may have valves or other fluid control mechanisms not shown in the figure. The coolant tubes 165 allow coolant 240 to flow into and out of the internal coolant passages 260 of the cold plate 160. The transport of coolant 240 through the internal coolant passages 260 of the cold plate 160 helps to remove heat from the transformer 120 by heat transfer, thereby maintaining the transformer 120 at a safe operating temperature during power conversion.

[0044] In another embodiment, the external coolant tube 165 or coolant conduit 165 may be integrated with the cold plate 160, joined to the coolant port 175 in other ways, and / or serve as an integrated extension of the internal coolant flow path 260.

[0045] As will be apparent to those skilled in the art, thin layers of various additional thermal conductive materials (not shown in Figure 1), such as thermal bonding materials or adhesives, may be used to facilitate bonding or adhesion between the surfaces of the coils 135.2, 135.1 and the core 145 and the surface of the cold plate 160. Such thermal conductive materials may also help maintain efficient and uniform heat conduction. In some embodiments, such thermal conductive materials may be applied in thin layers of the order of 1 mm or less, in other embodiments, thicker layers may be used, and in other embodiments, no additional thermal conductive materials or adhesives for bonding are used. Instead, the coils 135.2, 135.1 and the cold plate 160 may be joined together and thermal contact maintained via mechanical means such as screws (not shown), clamps (not shown), bolts (not shown), or via sealing and pressure from the surrounding core 145.

[0046] In another embodiment, the manufacturing process may involve (i) melting, partially melting, or chemically softening the thin surface layer and / or edges of the coils 135.2, 135.1 and / or the cold plate by means of heat, compression, or application of a surface solvent; (ii) mechanically pressing the coils 135.2, 135.1 and / or the cold plate together; and (iii) physically hardening the thus treated surfaces / edges to bond them together at a molecular level, thereby bonding some or all of the coils 135.2, 135.1 and the cold plate 160 together to maintain a permanent thermal contact state.

[0047] In another embodiment, two or more combinations of screws, clamps, bolts, cores 145, thermal conductive materials and adhesives, and chemical / thermal bonding may be used to maintain contact, pressure and the required thermal conductivity between the coils 135.2, 135.1 and the cold plate 160.

[0048] In the following description herein, "cold plate" may be abbreviated as "C", secondary / low-voltage coil as "S", and primary / high-voltage coil as "P". Various embodiments of this system and method may be shown in a simplified manner according to the stacking order of these components. For example, the stacking order in exemplary embodiment 100.1 shown in Figure 1 is "CSPCPSC".

[0049] Main (large) surface As is evident from the drawings, in some embodiments and configurations, some flat or substantially flat surfaces 190 of the cold plate 160, coil 135 and / or core 145 may be the largest surfaces of their components or one of two opposing largest surfaces. Such largest surfaces 190 are referred to herein as “primary surfaces” 190, and it will be apparent that such primary surfaces 190 are particularly well-suited for heat transfer to the cold plate 160. Smaller secondary surfaces 195 can similarly facilitate heat transfer. In another embodiment, some transformer components 135, 145 are substantially or substantially cubic, in which case the distinction between primary surfaces 190 and secondary surfaces 195 by area becomes meaningless.

[0050] Exemplary liquid cooling system (LCS) As will be apparent to those skilled in the art, a complete or functionally complete liquid cooling system 200 for transformer 120 includes not only the liquid cooling elements (LCS) 160, 165 and the coolant 240 of cooling system 100.1, but also a variety of additional components, some or all of which may be external and, in some cases, remote from transformer 120.

[0051] Figure 2 shows an exemplary liquid cooling system (LCS) 200 for an HPD-HF transformer 120 according to the present system and method. Among the exemplary LCS 200 and other LCS systems that fall within the technical scope described in the claims, the following may be used: (i) A transformer (TICP) 100 with the above-described example integrated cold plate in relation to Figure 1 (see also Figures 3, 4, 5 and 6); (ii) Exemplary fluid-immersion transformer (FIT) 700 (see also Figures 7, 8 and 6 for details); (iii) Any transformer that falls within the technical scope described in the claims.

[0052] As described above, the LCS200 includes one or more cold plates 160, which are bonded to, embedded in, or otherwise structurally attached / thermally bonded to the components of the HPD-HF transformer 120.

[0053] Cold Plate In the drawings, the cold plate 160 is shown as a substantially cubic shape having six substantially flat and mutually orthogonal surfaces, but other shapes are also possible. In some embodiments of the system and method, it may be advantageous to shape the cold plate into a non-cubic shape or into a modified cube with various extensions in order to improve compatibility with other components 135.2, 135.1, 145 of the transformer 100, to increase surface contact, or to increase current or magnetic interaction. In some embodiments of the system and method, it may be advantageous for the cold plate 160 to have a textured surface or non-linear (curved) portions, including, but not limited to, ridges, bumps, grooves, other textures, or variations in surface height, in order to reduce the weight of the cold plate 160, to provide additional thermal conductivity, or to provide auxiliary air cooling to the cold plate 160.

[0054] In some embodiments, the cold plate 160 may be made from one type of metal, one type of metal alloy, one type of ceramic material, one type of polymer material, a carbon-based material, or one type of non-ferrous, non-conductive, thermally conductive material. In other embodiments, the cold plate 160 may be made from two or more types of materials, for example, different types of materials may be used for the first side and the second side of the cold plate, and optionally a third material may be used for lining the internal flow channel 260 (described later). In one embodiment, the surface of the cold plate exposed to the air may have an insulating material attached to its exposed surface to prevent heat leakage, to prevent fire or burns, and / or to maintain maximum heat transfer through the coolant flow channel 260.

[0055] coolant flow path Inside the cold plate 160 are one or more coolant channels 260 that guide the coolant 240 through the cold plate 160. The number, geometric configuration, relative width and / or diameter (with respect to the dimensions of the cold plate), and arrangement of the coolant channels 260 shown in Figure 2 are illustrative only, and numerous alternative configurations of the coolant channels 260 may be used within the technical scope of this system and method. The coolant channels 260 may be bulk / macrochannels with a diameter similar to the minimum width 310 of the cold plate 160 (see Figure 3A), or they may be microchannels with a diameter substantially smaller than the minimum width 310 of the cold plate 160.

[0056] With respect to the coolant flow path 260, this specification refers to it as "inside" the cold plate 160, but "internal flow path" is understood to include a cooling flow path in which the metal surface of the cold plate 160 can partially extend or protrude above the flat, smooth, or raised surface of the cold plate 160, and / or a cooling tube (e.g., a metal tube) that carries the coolant 240 coupled to the flat, smooth, or raised surface of the cold plate 160.

[0057] Coolant tube One or more inlet coolant tubes 165.1 and one or more outlet coolant tubes 165.2 are used to move the liquid coolant 240 into and out of the coolant flow path 260 within the cold plate 160. Here again, the one inlet coolant tube 165.1 and one outlet coolant tube 165.2 shown in Figure 2 are merely illustrative, and many more coolant tubes 165 may be used (as in Figure 1). Both Figures 1 and 2 show the coolant tubes 165 moving in and out of the cold plate 160 along a narrow side surface 185, but this is merely illustrative. In another embodiment, one or more coolant tubes 165 may be mounted along a large flat surface 190 of the cold plate 160 to move the coolant in and out.

[0058] An exemplary cooling system 200 may include, for example, variations in the number of cold plates 160, one or more alternative or additional cold plates 160 bonded to the outer surface of the magnetic core 145 (see Figure 4), other alternative geometries, and other modifications that fall within the technical scope of the appended claims.

[0059] An exemplary cooling system 200 may include a pump / heat exchange subsystem 210, which in the appended claims is simply referred to as a "pump system (210)," which may also be referred to as a "regulating system" 210, a "filtration system" 210, a "coolant pretreatment system" 210, etc. Examples of the pump / heat exchange subsystem 210 include, but are not limited to, the following: (i) Liquid pump 215. In one embodiment, a first coolant pump 215 applies pressure to draw cryogenic coolant 240 into the cold plate 160 via the input coolant tube 165.1, and a second coolant pump 215 pressurizes either or both of the used coolant and / or fresh coolant (from the bypass / mixing valve 220) into the coolant pretreatment unit 225. The two pumps shown are illustrative only. Other pumps may be used, for example, a fresh coolant input pump (not shown) for drawing fresh cryogenic coolant 240 directly into the coolant tube 165 or into the heat exchanger 235. (ii) A heat exchanger 235 for removing heat from the high-temperature coolant 240 and transferring it to the environmental heat sink 295 and / or for cooling the liquid coolant 240 via the environmental cooling source 201. (iii) A bypass / mixing valve 220 that can recycle a portion of the heated coolant 240 by mixing a portion of the heated coolant 240 with fresh coolant 240, or by using low-temperature coolant 240 and recycled high-temperature coolant 240 alternately. (iv) A coolant pretreatment unit 225 capable of purifying or filtering the coolant 240 to remove metallic or nonmetallic particles, contaminants and foreign chemical substances, or supplying chemical additives (such as antifreeze) to the coolant 240. (v) A coolant storage tank 230 that provides short-term storage or coolant buffering for the coolant 240.

[0060] As will be apparent to those skilled in the art, the exemplary cooling system 200, in particular the pump / heat exchange system 210, may include other components not shown in Figure 2, such as valves; temperature sensors; pressure sensors; additional chemical or coolant storage tanks; an internal processor and memory that controls the cooling system 220 via software and firmware; an internal electrical system that powers the pump 215, valves, processor and memory, and input and output control / data ports for external monitoring of the cooling system 200. In some embodiments, such additional components form part of the structure of a power converter including one or more transformers equipped with PEBB LRUs and / or liquid cooling elements 100,700.

[0061] In embodiments of the present system and method, multiple components of the pump / heat exchange subsystem 210 may be housed in a common subsystem housing 280 and structurally integrated, resulting in convenient mounting and modularization. In embodiments of the present system and method, the components of the pump system 210 within the housing 280 may provide pressure, pre-treatment coolant, and heating coolant removal to multiple transformers 100 (the single transformer 100 shown in Figure 2 is illustrative and not limiting).

[0062] No air cooling or limited air cooling As is evident from the above description and drawings, and from the following description and drawings, the liquid transformer cooling of this system and method removes all or substantially most of the heat generated in the transformer 120 through heat transfer between the solid material components of the transformer and the cold plate 160 and the liquid coolant 240. In some embodiments, heat transfer through the ambient air immediately surrounding the transformer 120 may be essentially negligible.

[0063] In another embodiment, heat transfer from the transformer 120 through the surrounding air may result in some substantial or beneficial additional cooling, but the dominant mode of heat removal is still primarily by (i) the flow of heat from the transformer coils 135 and core 145 to the cold plate 160, and then (ii) the flow of heat from the cold plate 160 to the external environment heat sink 295 through the liquid coolant 240 flowing within the cold plate 160.

[0064] Cooling source and environmental heat sink The exemplary environmental cooling source 201 and exemplary environmental heat sink 295 shown in Figure 2 are understood to be significant environmental factors separate from the exemplary cooling system 200. For example, in the case of a power converter application for a ship, both the environmental cooling source 201 and the environmental heat sink 295 could be the general ship's treated water or chilled water supply system, or the water of the sea, ocean, or river in which the ship navigates. As another example, in the case of a power converter application for an aircraft, both the environmental cooling source 201 and the environmental heat sink 295 could be the air outside the aircraft.

[0065] Figure 3A shows an exemplary HPD-HF transformer 120 with an integrated cold plate (TICP) of the liquid cooling system 200 (see Figure 2). (In Figure 3A, the coupled transformer 120 with the integrated cold plate (TICP) is denoted by reference numeral 100.2). Some components of the exemplary TICP 100.2 are identical or substantially similar to the components of the exemplary TICP 100.1 in Figure 1 and / or the components of the cooling system 200 in Figure 2, and to avoid redundancy, we will refrain from repeating details of those components that have already been described in Figures 1 and / or 2.

[0066] Figure 3A shows a cross-sectional view of a transformer (TIPC) 100.2 with an integrated cold plate, and several components are omitted compared to the embodiment 100.1 in Figure 1. In the cross-sectional view of Figure 3A, the internal core element 147 is absent.

[0067] In TICP100.2, only one primary coil 135.1 is used, sandwiched between two secondary coils 135.2. Two cold plates 160 are used on the outer surface of the secondary coils 135.2. The cold plates 160 are also in thermal contact with the magnetic core 145. Coolant conduits 160 having internal flow channels 260 that penetrate the cold plates 160 (or heat exchange plates 160) are also shown. The stacking order of TLCS100.2 is "CSPSC".

[0068] Figure 3B shows another exemplary HPD-HF transformer 120 equipped with an integrated cold plate (TICP) 100.3 of the liquid cooling system 200. (In Figure 3B, the composite transformer 120 itself (TICP) equipped with the integrated cold plate (160) is denoted by reference numeral 100.3).

[0069] Figure 3B shows a cross-sectional view of a transformer (TIPC) 100.3 with an integrated cold plate, and several components are omitted compared to embodiment 100.1 in Figure 1. In the cross-sectional view of Figure 3B, the internal core element 147 is absent.

[0070] Some components of the exemplary TICP100.3 are identical or substantially similar to the components of the exemplary TICP100.1 in Figure 1 and / or the cooling system 200 in Figure 2, and we will avoid repeating details of those components that have already been described in Figures 1 and / or 2.

[0071] Figure 3B shows a cross-sectional view of TICP100.3, and several components are omitted compared to embodiment 100.1 in Figure 1. In TICP100.3, only one primary coil 135.1 and one secondary coil 135.2 are used, with one cold plate / heat exchange plate thermally coupled between them. The cold plate 160 is also in limited thermal contact with the magnetic core 145. The stacking order of TICP100.3 is "SCP".

[0072] Figure 4 shows another exemplary HPD-HF transformer 120 with an integrated cold plate (TICP) 100.4 of the liquid cooling system 200. Several components of the exemplary TICP 100.4 are identical or substantially similar to those of the exemplary TICP 100.1 in Figure 1 and / or the components of the cooling system 200 in Figure 2, and we will refrain from repeating details of those components that have already been described in Figures 1 and / or 2. In the cross-sectional view of Figure 4, an internal core element 147 is present (thus making it appear as though each of the two cold plates 160' and 160'' and each coil 135 are divided into two parts).

[0073] The TICP100.4 shown in Figure 4 omits several components compared to the embodiment 100.1 in Figure 1. In the TICP100.4, only one primary coil 135.1 and two secondary coils 135.2 are used. Four cold plates / heat exchangers 160 are used, (i) two cold plates 160' and 160'' are physically and thermally coupled to the respective surfaces of the two secondary coils 135.2 and are also in physical / thermal internal contact with the magnetic core 145, and (ii) two cold plates 160 are attached to the external surface of the iron core 145 and are thermally coupled. The stacking order of the TICP100.4 is "CFCSPSCFC".

[0074] The arrangement and sequence of the components of the primary coil 135.1, secondary coil 135.2, cold plate 160, and iron core members 145, 147 as illustrated and described in the above embodiments are illustrative and not limiting. Other arrangements can easily be envisioned within the technical scope of the appended claims, as will be further described below.

[0075] Generalized transformer component arrangement As will be apparent to those skilled in the art, and based on the above description and the associated drawings, various embodiments of the liquid-cooled transformer (100) may include, for example, (i) to (ix) below, individually or in combination: (i) The first main surface 190 (the largest surface or one of the two largest surfaces) of the cold plate 160 is in contact with and thermally coupled to the second main surface 190 of (i) the core 145 and (ii) at least one of the coil components 135.1, 135.2. The first and second main surfaces 190 are molded toward each other to promote enlarged surface contact, thereby facilitating effective heat transfer between the first and second main surfaces 190. (See, for example, Figures 1, 3A / 3B, 4, and 5). (Note that in Figure 1, the main contact surfaces of the core 145 and coil component 135 are not directly visible and are therefore not labeled.) (ii) A liquid-cooled transformer 160 as described in (i) above, wherein the first main surface 190 and the second main surface 190 are flat surfaces. (See, for example, Figures 1, 3A / 3B, 4, and 5). (iii) A single cold plate 160 having a first main surface 190 and a second main surface 190 facing it, wherein each of the two opposing main surfaces 190 is in contact with the main surface 190 of a different transformer component selected from the core 145 and two coil components (135.1, 135.2). (See, for example, Figures 1, 3A / 3B, 4, and 5). (iv) A single cold plate 160 is physically located between (a) the core 145 and one of the coil components 135.1, 135.2 (see Figures 1 and 3) or (b) at least one of the two coil components 135.1 (see Figures 1, 4 and 5), and is in physical contact with and thermally bonded along its main surface 190. (v) Two or more separate cold plates 160, which are configured and arranged to be in physical and thermal contact with two or more different non-adjacent transformer components selected from the core 145, the first coil component 135.1, and the second coil component 135.2 (see Figure 3A). (vi) Two or more separate cold plates 160, which are configured and arranged to be in physical and thermal contact with three or more different transformer components selected from the core 145, the first coil component 135.1, and the second coil component 135.2. (See Figures 1, 3, and 5). (vii) Two or more primary coils 135.1 and / or two or more secondary coils 135.2 (see Figures 1, 3 and 5) may be used. In such embodiments, two or more separate cold plates 160 are typically used, although they are not essential, and are sandwiched between various coils 135. (viii) The primary coil 135.1 and the secondary coil 135.2 are arranged in direct physical and thermal contact, and one or two cold plates 160 may be attached to the physically directly coupled coil 135 to remove heat from both. (ix) A single cold plate 160 may be configured to be in direct physical and thermal contact with two different coils 135 (135.1 / 135.1, 135.1 / 135.2, or 135.2 / 135.2) and also in direct physical and thermal contact with one or more cores 145 for heat removal from both the coils 135 and the cores. In some embodiments, this is achieved by bringing at least one of the subsurfaces 195 of the cold plate 160 into contact with the cores 145 and bringing the opposing main surfaces 190 of the cold plate 160 into contact with the two different coils 135.

[0076] In general, other geometric arrangements, shapes, and relative dimensions of the coils 135, cores 145, and cold plates 160 are also conceivable and may fall within the technical scope of the appended claims. For example, in embodiments not shown, the core 145 may be fixed as a layer between two coils 135.1 and 135.2 to form a block structure, and multiple cold plates 160 may be arranged on two, three, or up to six sides of the resulting block. Also, although the maximum number of primary and secondary coils 135 shown in the figure is two each, two or more coils 135 of a certain type (low voltage and / or high voltage) may be used if they are properly electrically coupled. Additional cold plates 160 may be used as needed.

[0077] Exemplary applications: power converters Figure 5 shows an exemplary power converter 500 using a liquid cooling system 200 or a liquid immersion transformer 700 (see Figure 7 and related descriptions below) according to the system and method. The exemplary power converter 500 may include, for example, (i) to (iv) below. (i) Two or more power electronics building block minimum compatible units (PEBBs) 510. Each PEBB 510.1, 510.2 has its own TICP 100, and other power elements 515 (not shown in detail in Figure 5), such as a bridge converter with a power switch. For a more detailed description of exemplary PEBBs 510, in particular a hybrid PEBB (HPEBB), see Figure 9 below. The two PEBBs 510.1, 510.2 are electrically / currently linked by one or more power couplings 530. The power converter 500 has at least a power supply (or input) power connection and one or more load (or output) power connections, but is not shown. (ii) One or more pump / heat exchange subsystems 210. In the illustrated embodiment, one pump / heat exchange subsystem 210 may supply coolant to all cold plates of the power converter 500. In another embodiment not shown, two or more pump / heat exchange subsystems 210 may be used. (iii) Other converter elements 520. Examples include, but are not limited to, additional or supplementary cooling systems (such as fan-type air cooling systems), control systems and circuits, monitoring systems, and input and output power ports. (iv) In addition to the cold plate 160.1 integrated with the transformer 100, an additional cold plate 160.2 may be provided for additional system cooling. Figure 5 shows four exemplary additional cold plates 160.2 that can be mounted externally to, for example, the PEBB 510, but other cold plates 160 may also be envisioned. Figure 5 also shows one exemplary cold plate 160.3 mounted externally to the power converter 500, but an additional external cold plate 160.3 may be used.

[0078] Although the two PEBB510.1 and 510.2 transformers 100 shown in Figure 5 utilize a "CSPSC" stacking arrangement, this is merely an example, and other stacking arrangements also fall within the technical scope of this system and the attached claims.

[0079] Some components of the exemplary TICP100', 100'' are identical or substantially similar to the components of the exemplary TICP100.1 in Figure 1 and / or the cooling system 200 in Figure 2, and we will avoid repeating details of those components that have already been described in Figures 1 and / or 2.

[0080] Coil components (coils) Figure 6A is a cross-sectional view of an embodiment of an exemplary solid coil component 135 (also simply referred to as "coil 135") of an exemplary transformer 100, the solid coil component 135 may be either a low-voltage / secondary coil 135.2 or a high-voltage primary coil 135.1. The conductive wire / metal film 610 may be arranged in any of several rows of flattened helical surface arrangements on the flat inner surface of the coil support material 620 such that the wire / metal film 610 is completely embedded in the coil support material 620 except for the external electrical connection portion 640. In accordance with this system and method, other coil windings or wound surface patterns (not shown) may be similarly applied to the conductive wire / metal film 610, which remains completely embedded in the coil support material 620 except for the external electrical connection portion 640. Figure 6B shows two cross-sectional views (I, II) of another exemplary embodiment of a solid coil component 135 (also simply referred to as "coil 135") of an exemplary transformer 100, the solid coil component 135 may be either a low-voltage / secondary coil 135.2 or a high-voltage primary coil 135.1. In the illustrated cross-sectional embodiments, the conductive wire 610 or metal film 610 of the coil 135 may be wound around a flattened section 620.1 of the coil support material 620, and the wire 610 and the flattened section are further embedded within the encapsulation block 620.2 of the coil support material 620.

[0081] In another embodiment (not shown), the conductive wire / metal film 610 may be arranged in any of the following configurations: a variety of flattened helical surface arrangements on the narrow inner surface or microchannel inner surface of the coil support material 620, or other flattened winding surface patterns (suitable for magnetic induction by current), and it remains completely embedded within the coil support material 620 except for the external electrical connections 640. In accordance with this system and method, other geometric coiled or winding arrangements (not shown) may be similarly applied to the conductive wire / metal film 610, in which the filament remains completely embedded within the coil support material 620 except for the external electrical connections 640.

[0082] In another embodiment (not shown), the coil 135 may be configured such that a portion of the wire / filament 610 is embedded inside the coil support material 620, wound around and / or coiled, and the portion of the wire / filament 610 may be in close proximity to one or more outer surfaces of the solid coil 135, or partially or entirely exposed, with appropriate electrical insulation as an option.

[0083] As will be apparent to those skilled in the art, the wire / filament 610 may be arranged or configured in relation to the coil support material 610 such that (i) the coil support material 620 absorbs substantially all of the heat generated in the wire / filament 610, and (ii) the solid coil component 135 has one or more exposed outer surfaces suitable for dissipating heat to a thermally bonded adjacent material (which may be either the cold plate 160 or another solid coil 135, or an ambient heat-conductive fluid 740 such as oil 740).

[0084] Coil material In embodiments of this system and method, the coil support material 620 may be silicon. In other embodiments, one or more coil support materials 620 may include, for example, resins, epoxy, ceramics, glass, or other nonconductive but thermally conductive substances or materials, but are not limited to these. The coil 135 may also include, for example, (i) polymers or polymer composites (for insulation), such as epoxy or bisphenol A type epoxy with 60 wt% quartz filler added, and / or (ii) ceramics (e.g., alumina) used for insulation as an alternative to polymers or polymer composites.

[0085] In one embodiment, the coil support material 620 is selected so as to be easily maintained (without melting, breaking, burning, or otherwise collapsing) even at temperatures of up to 200°C that may occur in the conductive (typically metallic) coil 610 embedded inside it.

[0086] conductive materials In exemplary embodiments, the coil 135 may be made from a metal or metal alloy such as Litz wire, or from another metal or metal alloy.

[0087] Exemplary HPD-HF type fluid immersion transformer In one embodiment of the system and method, as an alternative or addition to the embodiments described herein, the entire HF transformer 120 may be structurally fixed and / or suspended within a substantially sealed container 710. The entire container may be filled with a non-conductive but thermally conductive fluid 740, such as mineral oil ("oil"), so that the transformer 120 is immersed in the oil 740 or other thermally conductive fluid 740.

[0088] In one embodiment, the selected oil 740 is the heat transfer medium from the transformer 120. The oil 740 is both an excellent heat transfer medium and an excellent electrical insulator. Furthermore, using the fluid 740 as the heat transfer medium ensures that the heat transfer medium, whether oil or another heat transfer fluid, is in complete contact with all exposed surfaces of the transformer 120 for optimal heat removal.

[0089] Compared to air as a potential cooling medium, oil 740 has a high heat capacity and good thermal conductivity. Table 1 shows the approximate relative heat capacity and thermal conductivity of water, air, and oil (selected for the operating temperature and pressure range applicable to this system and method). For simplicity, a normalized heat capacity of 1 is assigned to air. Note that (1) relative heat capacity and thermal conductivity vary depending on the type of oil used, and (2) water has significantly better heat capacity / thermal conductivity than oil, but due to its electrical conductivity, it cannot be used as the liquid 740 for direct immersion of the transformer 120. However, water is suitable for use in the cooling channel 260 of the cold plate 160.

[0090] [Table 1]

[0091] Figure 7 shows an exemplary HPD-HF transformer 120 immersed in a heat transfer fluid (HTF) 740 (which may be oil 740) according to one embodiment of the system and method, all of which are housed in a thermal management enclosure (HME) 710 with a cold plate 160 attached to or integrated on its surface.

[0092] In Figure 7, the composite transformer 120 itself (hereinafter referred to as the "fluid-immersion transformer" (FIT)) comprising the HTF740, HME710, and cold plate 160 is denoted by the reference numeral 700.1. FIT700.1 may include, for example, a high power density / high frequency (HPD-HF) transformer 120 that can be used for pulse load power conversion applications.

[0093] In one embodiment, the exemplary FIT700.1 forms a structurally integrated unit, in other words, is physically and / or thermally coupled with the structure of the HPD-HF transformer 120 together with several components 160, 165, 710, 740 of the liquid cooling system 200. The FIT700.1 is configured / assembled in an SPPS configuration with two primary (high voltage / HV) coils 135.1 and two secondary (low voltage / LV) coils 135.2.

[0094] Spatial gap for cooling fluid In the embodiment shown in the figure, a spatial gap 730 exists between the large planes of the two high-voltage coils 135.1. This spatial gap 730 allows the heat transfer fluid (HTF) 740 to fill the gap 730, thereby increasing the rate of heat transfer between the high-voltage coils 135.1 and the HTF 740. In another embodiment, the gap 730 is absent or filled with a non-conductive material.

[0095] Thermal management enclosure The transformer 120 may be mounted on one or more inner surfaces 755 of the housing 710, or it may be mechanically coupled to the housing 710 via mounting fixtures 805 such as struts and brackets and suspended within the housing (see Figure 8). As shown in Figure 7, the transformer 120 may be positioned within the housing 710 such that it is substantially surrounded by the HTF 740 on multiple sides and / or multiple surfaces of the transformer.

[0096] The thermal management enclosure (HME) 710 is sealed to prevent fluid leakage and has a suitable fluid-sealing port (not shown) for electrical connection to the transformer 120. One or more cold plates 160 are provided on one or more outer walls / surfaces 755 of the HME 710 and are preferably bonded to the HME 710 for effective heat transfer between the HME 710 and the cold plates 160. Two cold plates 160 are shown in Figure 7, but additional cold plates 160 may be placed on another outer surface 755 of the HME 710. In one embodiment, the cold plates 160 are substantially the same shape as the walls / surfaces of the enclosure (e.g., rectangular).

[0097] In another embodiment, a different shape (e.g., circular or elliptical) may be used for the cold plate 160. In another embodiment, the HME 710 may have a shape other than a cube (e.g., spherical, oval, or having six or more flat outer surfaces 755) and have a shape suitable for mounting the cold plate 160 in order to ensure effective thermal contact between the cold plate 160 and the HME 710.

[0098] The HME710 can be made of a material suitable for containing the high-temperature fluid 740 and for transferring heat from the fluid 740 to the cold plate 160. Such materials include, but are not limited to, metals or metal alloys (preferably non-ferrous metals), ceramic materials, polymer materials, glass materials, or carbon composite materials, which are properly electrically insulated from the transformer 120.

[0099] In another embodiment, the HME710 and the cold plate may be molded, cast, or metal-joined to form a single integrated structural unit. In such an embodiment, the cold plate 160 can be seen as one or more thickened walls 755 of the thermal management housing 710 through which the coolant flow path 260 penetrates the thickened walls of the HME710.

[0100] During the operation of the transformer, the heat generated in the winding coils 135.2, 135.1 and the magnetic core body 145 is transferred / transported to the HME enclosure / wall 755 via the HTF740.

[0101] coolant / liquid Two different cooling fluids / liquids may be used with respect to the exemplary fluid-immersion transformer 700.1. For example, the thermal conductive fluid (HTF) 740 may be an oil or other complex hydrocarbon liquid that is effective for heat transfer but also an effective electrical insulator, and the liquid coolant 240 flowing through the cooling channel 260 of the cold plate 160 may be, for example, but not limited to, tap water, industrial water, chilled water, deionized water, seawater, or water treated with a suitable conditioning fluid such as antifreeze, and optionally an oily coolant, organic liquid coolant, or silicone-based coolant. Other coolants may also be used in accordance with the appended claims.

[0102] In embodiments configured to use a potentially corrosive coolant 240 (for example, saline seawater or ocean water used in shipboard power converters), an appropriate anticorrosive material or lining may be used on the inner surface of the coolant channel 260. In another embodiment, a filter element (not shown) may be used to filter out potentially corrosive substances.

[0103] Further details of the exemplary cold plate 160 and coolant flow path 260 have already been described herein and will not be repeated here.

[0104] Pump system The pump / heat exchange subsystem 210 (referred to as the "pump system 210" in the appended claims) may be required to provide the required flow rate, pressure, and liquid quality (e.g., filtration), remove most of the waste heat generated by the transformer 120, and minimize the heat released into the surrounding environment. Such a pump system may include, for example, but not limited to, a pump, valves, a heat exchanger, coolant pretreatment components (e.g., filtration, degassing, iron removal, etc.), and a coolant 240 storage tank. A pump system 210 identical or substantially similar to the exemplary pump / heat exchange subsystem 210 in Figure 2 can be used here, so a repetition of the details will be avoided.

[0105] Circulation of thermally conductive fluids In another embodiment not shown, circulating the HTF740 within the HME710 may be advantageous for heat conduction. For this purpose, an internal fan or pump system (not shown in Figure 7) may be built into the HME710. In another embodiment, a separate HTF pump system may be located outside the housing 710, and appropriate tubing may be provided to circulate the HTF740 within the internal space of the HTF740.

[0106] Additional Embodiments of Fluid Immersion Transformers Figure 8 shows cross-sectional views of several other embodiments of an exemplary fluid-immersed current transformer (FIT) 700 according to another embodiment of the System and Method, in which the transformer 120 can be immersed in a heat transfer fluid (HTF) 740, and the whole is housed in a thermal management enclosure (HME) 710 to which a cold plate 160 is attached.

[0107] In Figure 8, FIT740 is numbered 740.2 to 740.5. FIT740.2 to 740.5 are generally configured and arranged in the same manner, arrangement, and configuration as the exemplary FIT740.1 in Figure 7. Some details that have already been explained in Figure 7 and other drawings will not be repeated.

[0108] In Figure 8, in one embodiment of the system and method, FIT700.2 includes one primary (high voltage / HV) coil 135.1 and one secondary (low voltage / LV) coil 135.2 in an SGP configuration with a fluid gap 730 between them. The cooling channel 260 of the cold plate 160 is perpendicular to the plane of the cross-sectional view.

[0109] In another embodiment, as shown in FIT700.3, the transformer 120 has one primary (high voltage / HV) coil 135.1 and one secondary (low voltage / LV) coil 135.2 (PS configuration) in direct physical and thermal contact with each other. Struts 805 or other mechanical connections may be used to secure the transformer 120 to the inner wall of the HME710. Heat is dissipated through the HTF740 on the sides, top, and bottom of the transformer 120. The cold plate 160 has numerous microchannel coolant flow paths 260 perpendicular to the plane of the cross-sectional view. FIT700.3 shows exemplary transformer electrical connections 185, which are always present in the transformer 120 even if not shown.

[0110] In another embodiment, as shown in FIT700.4, the transformer 120 has two primary (high voltage / HV) coils 135.1 and one secondary (low voltage / LV) coil 135.2, with two gaps 780 filled with HTF740 between the three coils 135, forming a PGSGP configuration. Cooling fluid is also present in the internal space of the housing 710 on the input and output sides of the transformer 120. Heat is carried away through the HTF740 on the sides, top and bottom surfaces of the transformer 120. The cold plate 160 has numerous microchannel coolant flow paths 260 parallel to the plane of the cross-sectional view.

[0111] In another embodiment, as shown in FIT700.5, the transformer 120 comprises two primary (high voltage / HV) coils 135.1 and one secondary (low voltage / LV) coil 135.2, all in physical and thermal contact with each other, forming a PSP configuration. The transformer 120 is suspended within a thermal management enclosure (HME) 710 via struts 805 and other mechanical connections. Heat is dissipated through HTF 740 on the sides, top and bottom of the transformer 120.

[0112] Cooling fluid is also present in the internal space of the housing 710 on the input and output sides of the transformer 120. Heat is carried away through the HTF 740 on the sides, top, and bottom of the transformer 120. The cold plate 160 has numerous microchannel coolant flow paths 260 parallel to the plane of the cross-sectional view.

[0113] As will be apparent to those skilled in the art, the embodiments of FITS700 shown in Figures 7 and 8 are illustrative only, and various combinations of components from different exemplary embodiments are possible. Other configurations / embodiments are possible within the technical scope of this system and method, for example, but are not limited to, the coil 135 may be arranged in configurations such as SPS, SGPS, SPGS, SGPGS, SPPS, SGPS, SGPS, or other configurations.

[0114] Heat transfer In the FIT700, the transformer body 120 is immersed in an oil-like HTF 740. The heat generated in the transformer 120 is transported through the oil 740 to the outer casing / enclosure wall 755 of the HME 710. This heat is then removed by the coolant 240 flowing through the coolant channels of the cold plate 160, which is in physical and thermal contact with the enclosure casing / wall 755.

[0115] Additional FIT implementations In some exemplary embodiments of the present system and method relating to FIT700, the cold plate 160 (also referred to as the “heat exchanger plate” 160) is configured parallel to the plane of the coil 135, as shown in the drawings. In an alternative embodiment, the cold plate 160 may be mounted on the outer surface of the housing wall 755 along a plane perpendicular to the plane of the coil 135. In an alternative embodiment, two or more cold plates 160 may be mounted along different outer surfaces of 755 of the HME 710, so that some cold plates 160 are mounted parallel to the plane of the coil 135 and others are mounted perpendicular to the plane of the coil 135. In another embodiment, mounting one cold plate 160 on one wall 755 of the housing 710 may be sufficient to cool the transformer 120.

[0116] In another embodiment, one or more cold plates 160 may be placed inside the HME 710, and suitable coolant pipes 165 may be installed to allow the coolant 240 to flow through the cold plates.

[0117] In another embodiment, an oil pump system may be used to circulate the oil 740 inside the HME 710.

[0118] In another embodiment, two or more transformers 120 may be housed in a single thermal management enclosure 710, and a cold plate 160 may be attached to one HME 710 to remove the heat generated by all the transformers.

[0119] As will be apparent to those skilled in the art, many details of a final design may vary depending on the application specifications, including the power to be generated by the transformer and the spatial constraints for the intended power converter application. Therefore, details such as the number of coils 135, the number and dimensions of cores 145, the dimensions / weight / material / placement of the cold plate 160, the number and cross-sectional shape of the coolant flow channels 260, the type of coolant fluid 240,740 to be used, and many other specific design factors are determined and optimized according to the specific application. For a particular TICP100 or FIT700, laboratory and real-world testing of proposed design selections may be required to identify the optimal or near-optimal selection of specific structures, materials, and configurations.

[0120] In addition to the transformer components 135 and 145 described in detail above, the transformer 120 may include various additional components, such as current / electrical connectors 185 and various screws, nuts, bolts, clamps, braces and other physical components, which generate heat (e.g., current / electrical connectors (185)) or receive heat from coils 135 and / or cores 145. The heat-transferring fluid 740 may also physically contact and transfer heat to the exposed portions of these additional transformer components, thereby removing heat from the exposed surfaces of the additional physical components.

[0121] coolant / fluid In various embodiments, the system and method transfer heat from transformer components / parts 135, 145 to any of the following (i) to (ii) using several stages of heat transfer and thermal convection facilitated by direct physical contact. (i) By conduction, and further by thermal convection caused by the coolant 240 flowing within the cold plate 160, to the cold plate 160, (ii) By convection in the thermally conductive fluid 740, the heat is transferred to the wall 755 of the thermal management enclosure 710 that houses the transformer 120 and the thermally conductive fluid 740, and then by conduction, and further by thermal convection caused by the coolant 240 flowing inside the cold plate 160, to the cold plate 160 attached to the wall 755.

[0122] In the embodiments described above, the coolant 240 and thermally conductive fluid 740 used are generally characterized as liquids / fluids (such as water or aqueous liquids, or most oils) that are normally liquid at room temperature, and more generally, are liquid in the temperature range above the freezing point of water. Such fluids can be easily stored and transported via pipes and conduits. Hereinafter, for convenience, these coolants will be referred to as "room temperature coolants."

[0123] Such room-temperature coolants may have advantages such as (i) being readily available in large quantities (for example, large quantities can be drawn from seawater, river water, or seawater in ship-mounted power converters, and from rivers in compact land-based power converters), and / or (ii) being commercially available (various oils, etc.), and / or (iii) being easily and conveniently stored in relatively lightweight storage tanks. Such coolants may not require special compressors.

[0124] In another embodiment, a liquid / fluid 240,740 that is normally a gas at room temperature can be used (either as a whole or supplementing to a "room temperature" fluid), and therefore must be compressor-cooled or supercooled to be used as a liquid. Examples of such supercooled fluids include, but are not limited to, liquid nitrogen, liquid helium, liquid oxygen, liquid carbon dioxide, and various commercially available coolants. As will be apparent to those skilled in the art, users of these liquids may require a compressor, special storage tanks, and other components not described herein. Therefore, embodiments of the system and method having such a compressor / supercooled fluid are heavier and require more power for cooling than embodiments using a room temperature fluid. However, such embodiments may be useful in ultra-dense / compact power converters and future power converters designed for higher levels of power generation (e.g., higher voltage power switches and higher transformer winding ratios) in very compact spaces.

[0125] Comparison with air-cooled transformers Compared to air-cooled transformers, this system and method (typically using a room-temperature coolant / fluid, though not essential) offers several advantages. These advantages include, but are not limited to, the following: (i) Compared to air-cooled HF solid-state transformers, volume reduction (approximately 35%) (ii) Compared to air-cooled HF solid-state transformers, improved power density (~1.5 times), (iii) Reduced heat release to the surrounding environment (i.e., reduced heating of the air for human activity and breathing in the room or facility housing the power converter), further contributing to a reduction in the demand for air conditioning / cooling for the human environment, and (iv) Both the TICP 100 and the FIT 700 transformers with integrated cold plates offer superior suitability for the confined / constrained spaces of military and commercial vessels (compared to air-cooled transformers), and the reduced space allows for beneficial use of "space-saving" for other purposes.

[0126] Example use: HPEBB Figure 9 shows an exemplary power electronics building block (PEBB) 510 using the liquid / fluid cooling system 200,700 (see Figures 2, 5, and 7 and the relevant descriptions above) relating to this system and method. Specifically, Figure 9 shows an exemplary hybrid power electronics building block (HPEBB) 510. Note that PEBB may also be referred to as a "[Hybrid] Power Electronics Building Block Minimum Compatible Unit" (PEBB LRU or HPEBB LRU) 510 / 510.1.

[0127] Conventional PEBB510s typically use power switches 915 with equal voltage ratings throughout the PEBB510 (e.g., 1700V for nominal operation at 1000V). Conventional PEBBs typically use high-power transformers 120 with a 1:1 winding ratio.

[0128] The exemplary HPEBB LRU510.1 uses both a low-voltage switch and a high-voltage switch 915 (hence the term "hybrid"), which in some embodiments may be silicon carbide (SiC) switches. For example, in the exemplary embodiment, the low-voltage switch 915.1 may be a 1700V rated switch for nominal operation at 1000V, and the high-voltage switch 915.2 may be a 10000V rated switch for nominal operation at 6000V. Generally, if the operating voltages are represented by A and B (where B > A), A can be, for example, 1000V or 2000V or other voltages, and B can be, for example, 2000V, 3000V, 6000V or other voltages, and so on. The system and method for liquid cooling are designed for cooling the HPEBB LRU510 and power converter 500, which in part utilize the high-power switch 115.2 that was under development (and just emerging) at the time of filing this application.

[0129] The example HPEBB LRU510 also uses a high-power high-frequency transformer 120 with a winding ratio K:N (N>K, K=1, 2…, N=2, 3…).

[0130] In various embodiments, the HPEBB type converter 500 according to this system and method requires fewer HPEBB LRUs 510 than the number of conventional PEBB LRUs (conventional PEBBs are called "PEBB1000LRUs" and typically only rated power switches for nominal 1000V operation are used) required in conventional systems. Therefore, the power converter 500 according to this system and method can reduce the total volume and weight of the power converter 500 and increase the power density and specific power output of the power converter 500. In one embodiment of this system and method, the power switch 915 is implemented as a MOSFET (metal-oxide-semiconductor field-effect transistor) in parallel with the diode, as shown in Figure 9. In another embodiment, the power switch 915 is implemented as an IGBT (insulated gate bipolar transistor) in parallel with the diode, as shown in Figure 9. As will be apparent to those skilled in the art, the power switch 915 may be implemented within the technical scope of this system and method as one or more power transistors and other components such as GaN (gallium nitride) wide-bandgap devices, JFETs, IGCTs (integrated gate commutation thyristors), and diodes.

[0131] In the exemplary HPEBB LRU 510 of Figure 9, a total of four bridge transducers 910 are used. In other embodiments, a total of two or more bridge transducers 910 may be used. In the art, bridge transducers 910 may also be referred to by other terms, including, but are not limited to, power stages, power bridges, H-bridge transducers, and full-bridge transducers.

[0132] The exemplary HPEBB LRU510 also illustrates a K:N (N=2, 3…) high-frequency (HF) transformer 120 configured to couple a low-voltage element 905.1 and a high-voltage element 905.2. That is, the exemplary HPEBB510 couples the low-voltage element 905.1 and the high-voltage element 905.2 via a high-frequency (HF) transformer 120 with a winding ratio higher than 1 (1:1), such as a K:N ratio of 1:3 or 1:6, for example, but not limited to.

[0133] In some embodiments of this system, the exemplary high-power switching device 915.2 may consist of or include a 10kV SiC MOSFET under development by Cree Corporation (Durham, North Carolina, USA, Silicon Drive 4600) at the time of filing of this application. In exemplary embodiments, the bridge converter 910.1 on the low-voltage side 905.1 may use a 1.7kV SiCMOSFET / IGBT device, and the bridge converter 910.2 on the high-voltage side 905.2 may use a 10kV SiC MOSFET / IGBT device. In exemplary embodiments comprising an HF solid-state transformer 120 with a winding / turns ratio of 1:3 (1 on the low-voltage side and 3 on the high-voltage side), multiple such HPEBB510s may be configured as a single power converter for 1kVdc-13.8kVAC power conversion with good space and power density efficiency.

[0134] In another embodiment, the high-power switch 115.2 may be implemented via other known or under-development high-power switches, including, but not limited to, high-power MOSFETs and / or high-power IGBTs. The high turns ratio (e.g., 1:3) of the HF transformer 120 provides a voltage boost, ensuring that the hybrid PEBB (1000 / 6000) is not voltage-limited even in high medium-voltage (MV) (>12kV) applications.

[0135] HPEBB thermal management The K:N high power density / high frequency transformer 120, which provides galvanic isolation between the low-voltage side component 905.1 and the high-voltage side component 905.2, may generate a level of heat (and rate of heat generation) sufficient to benefit from the exemplary cooling systems 100, 200, 700 described throughout this specification. As a result, the HPEBB LRU510 may include cooling elements, including, for example, the cooling fluids / liquids 240, 740 described throughout this specification, but not limited to these.

[0136] electric Volume and weight of the force transducer The volume and weight of the hybrid PEBB LRU converter 510 increase slightly with the use of PEBB6000 components 910.2 and 915.2 on the primary side, i.e., the high-voltage side 905.2, and may increase further depending on additional cooling requirements. However, because the total number of HPEBB LRU510 required is reduced (compared to conventional power converters), in various embodiments, the total volume and weight of the exemplary 1kVdc-13.8kV 1MW hybrid PEBB power converter 510 are significantly reduced (compared to the weight / volume of a conventional PEBB1000LRU power converter of the same voltage / power capacity).

[0137] In response to this, in various embodiments, the system provides an HPEBB power converter 500.1 in which the power density and specific power output are significantly increased (compared to the power density / specific power output of a conventional PEBB1000LRU type power converter having the same total power capacity) by using the HPEBB LRU510 with the cooling system and method of the present invention.

[0138] An exemplary HPEBB power converter 500 is typically housed in a cabinet or housing 525 (see Figure 5), which houses all of the components described above and other components known in the art but not shown. The cabinet 525 may house or mount, for example, various internal structural support elements (not shown), a system bus, a power bus, ports for connection to external elements and external systems, vents for airflow, piping or ducts for coolants associated with the cooling system 525, an external status display, electronics for feedback and control systems (including processors and memory), and other components not shown in Figure 2.

[0139] The cabinet or housing 525 may house one or more components of the cooling system 210, as described in detail herein.

[0140] control system In various exemplary embodiments, the system and method may require the use or integration of a control system for regulating switches, capacitors, cooling systems, valves, pumps, filters, and other factors requiring real-time control. Such a control system may require the use of a microprocessor known or to be developed in the art, digital input / output elements, memory (such as random access memory (RAM) and various forms of non-volatile memory), a display system, an audio input and / or audio signaling system, and / or analog control elements. Such a control system may use appropriate coded software stored in memory to control various aspects of system operation.

[0141] When computer code is required for the system and method, such as a control system operating on a microprocessor, the computer-readable code can be provided as computer data signals embodied on known computer-readable media, including semiconductors, magnetic disks, optical disks (CD-ROMs, DVD-ROMs, etc.), and computer-readable (e.g., computer-readable) transmission media (including carrier waves and other digital, optical, and analog media). In this way, the code can be transmitted over communication networks, including the Internet and intranets.

[0142] Furthermore, the control or monitoring functions to be achieved in relation to the above-mentioned systems and technologies can be represented by cores (such as CPU cores) embodied in program code, and can be converted to hardware via appropriate circuits, wireless communication, and / or optical messaging.

[0143] conclusion For marine applications, including naval applications such as the U.S. Navy Power and Energy Systems (NPES) technology, the HPEBB Bridge Converter 910, HPEBB LRU510, and Power Converter 500 are being developed as part of the Multifunctional Energy Storage Module (MFESM) initiative. In particular, the emerging hybrid PEBB LRU510 utilizes high-power transformers that can generate significant heat in a compact space. The HPD-HF transformer liquid / fluid cooling system 200 of this system and method offers considerable advantages in managing the heat generated in such systems.

[0144] Those skilled in the art will be able to make alternative embodiments, examples, and modifications that are still included in this disclosure, particularly in light of the teachings described above. Furthermore, the terms used in this disclosure are descriptive and not limiting.

[0145] It will be apparent to those skilled in the art that various adaptations and modifications of the preferred and alternative embodiments described above can be made without departing from the technical scope of this disclosure. Accordingly, this disclosure can be implemented in forms other than those specifically described herein, within the technical scope of the appended claims.

[0146] The present invention has been described above using functional configuration blocks that illustrate specific examples of particular functions and their relationships. For the sake of explanation, the boundaries of these functional configuration blocks are defined arbitrarily in this specification. Alternative boundaries can be defined as long as the predetermined functions and their relationships are properly implemented.

[0147] The simulation, synthesis, and / or manufacture of various embodiments of the present invention can be achieved in part by the use of a variety of materials, including metals, nonmetals, resins, epoxy, semiconductors, glass, polymers, ferrous materials, nonferrous materials, conductors, insulators, and cooling water or aqueous liquids, cooling oils, and other hydrocarbon liquids, whether known or undeveloped in the art.

[0148] The section describing embodiments for carrying out the invention (not the section describing the summary of the invention or the abstract) is primarily intended for use in interpreting the claims. The section describing the summary of the invention and the abstract describe one or more embodiments conceived by the inventor, but do not necessarily describe all of them, and do not limit the scope of the present invention or the attached claims.

[0149] In the attached claims, the reference numerals are for the purpose of understanding the claims and do not limit the scope of protection of the claims; their sole function is to provide clear references to each component in the specification and drawings. [Explanation of symbols]

[0150] 100 Liquid-cooled transformers 120 transformer 135 Coil components 145 Transformer core 160 Cold Plate 165 Coolant tube 175 Coolant Port 185 Electrical connection 190 Main surface 195 Subsurface 200 Liquid Cooling System 201 Environmental cold source 220 Bypass / Mixing Valve 225 Coolant pretreatment unit 230 Coolant storage tank 235 Heat exchanger 240 Coolant 260 Coolant flow path 280 cabinets 295 Environmental Heatsink 525 Cabinet or Housing 610 Conductive materials 700 Fluid Immersion Transformer 710 Thermal Management Enclosure

Claims

1. A liquid-cooled transformer (100), wherein the liquid-cooled transformer (100) is Each of the coil components (135) is for conducting current, A core (145) configured to transmit magnetic flux between the plurality of coil components (135), A cold plate (160) that is in surface contact and thermally bonded to at least one of the core (145) and the plurality of coil components (135) A liquid-cooled transformer (100) comprising a cold plate (160) including a coolant channel (260) configured to carry a liquid coolant (240) within the cold plate (160).

2. The liquid-cooled transformer (100) according to claim 1, wherein the cold plate (160) contains a non-ferrous metal.

3. The liquid-cooled transformer (100) according to claim 1, wherein the cold plate (160) is provided with two or more coolant ports (175) for the inflow and outflow of the liquid coolant (240).

4. The coil component (135) is A continuous conductive material (610) which is wound, coil-wound, or surface-patterned to generate magnetic flux when an electric current flows through the conductive material (610), A thermally conductive non-conductive non-ferrous coil support material (620) configured to substantially house or embed the conductive material (610) and to transfer heat from the conductive material (610), and A liquid-cooled transformer (100) according to claim 1, including the following:

5. The liquid-cooled transformer (100) according to claim 1, wherein the first surface of the cold plate (160) and at least one second surface of the core (145) and the coil components (135.1, 135.2) to which the cold plate is thermally bonded are molded to each other to promote enlarged surface contact, thereby promoting effective heat transfer between the second surface of at least one of the core (145) and the coil components (135.1, 135.2) and the first surface of the cold plate (160).

6. The liquid-cooled transformer (160) according to claim 5, wherein the first surface and the second surface are flat surfaces.

7. A liquid-cooled transformer (100) according to claim 1, wherein a single cold plate (160) has a first surface and an opposing second surface, and each surface is in contact with a different of a plurality of transformer components selected from the core (145) and the two coil components (135.1, 135.2).

8. The cold plate (160) The core (145) and one of the coil components (135.1, 135.2), and Both of the aforementioned coil components (135.1, 135.2) A liquid-cooled transformer (100) according to claim 1, which is physically located between, in physical contact with, and thermally coupled to at least one of the following.

9. The liquid-cooled transformer (100) according to claim 1, further comprising two or more separate cold plates (160), the two or more cold plates (160) being configured and arranged to be in physical and thermal contact with two or more different non-adjacent transformer components selected from the core (145), a first coil component (135.1), and a second coil component (135.2).

10. The liquid-cooled transformer (100) according to claim 1, further comprising two or more separate cold plates (160), the two or more cold plates (160) being configured and arranged to be in physical and thermal contact with three or more different transformer components selected from the core (145), a first coil component (135.1), and a second coil component (135.2).

11. A fluid immersion type transformer (FIT) (700), wherein the fluid immersion type transformer (700) is i) a plurality of coil components (135, 145) each having a plurality of coil components (135) for conducting electric current, and (ii) a core (145) configured to transmit magnetic flux between the plurality of coil components (135), A thermal management enclosure (710) that houses the transformer components (135, 145) and is configured to include a thermally conductive fluid (740), wherein the thermally conductive fluid (740) is suitable for transferring heat from the plurality of coil components (135) and the core (145) to the outer wall (755) of the thermal management enclosure (710), A cold plate (160) is in surface contact with the outer wall (755) of the heat management housing (710) and is thermally bonded to it, or is integrated with the outer wall (755) of the heat management housing (710). The cold plate (160) includes a coolant channel (260) configured to transport a liquid coolant (240) within and through the cold plate (160), A fluid-immersion type transformer (700) in which the heat transferred from the transformer components (135, 145) to the outer wall (755) is further removed by being transferred to a liquid coolant (240) flowing through the cold plate.

12. The fluid immersion transformer (700) according to claim 11, wherein the cold plate (160) contains a non-ferrous metal.

13. The fluid immersion transformer (700) according to claim 11, wherein the cold plate (160) is provided with two or more coolant ports (175) for the inflow and outflow of the liquid coolant (240).

14. The coil component (135) is A continuous conductive material (610) which is wound, coil-wound, or surface-patterned to generate magnetic flux when an electric current flows through the conductive material (610), A thermally conductive non-conductive non-ferrous coil support material (620) configured to substantially house or embed the conductive material (610) and to transfer heat from the conductive material (610), and A fluid-immersion type transformer (700) according to claim 11, including the following:

15. The fluid-immersion type transformer (700) according to claim 11, wherein the thermally conductive fluid (740) is a non-conductive oil.

16. The fluid-immersion type transformer (700) according to claim 11, wherein the liquid coolant (240) is an aqueous fluid.

17. The fluid-immersion transformer (700) according to claim 11, wherein the plurality of transformer components (135, 145) are configured to have a spatial gap (730) between two or more of the components (135, 145), and the thermally conductive fluid (740) fills the spatial gap (730) to increase thermal convection.

18. A fluid-immersion type transformer (700) according to claim 11, comprising three or more coils (135).

19. The fluid immersion transformer (700) according to claim 11, wherein one or more of the cores (145) and one of the coils (135) are in direct physical and thermal contact with the inner surface of the thermal management housing (710).

20. All of the coils (135) and cores (145) are suspended within the thermal management housing (710) via struts (805), and The fluid-immersion transformer (700) according to claim 11, wherein the coil (135) and the core (145) are all in direct physical and thermal contact and all sides are substantially surrounded by the thermally conductive fluid (740).

21. All of the coil (135) and the core (145) are suspended within the thermal management housing (710) via struts (805). A spatial gap (730) exists between two or more of the aforementioned parts (135, 145). The fluid-immersion transformer (700) according to claim 11, wherein the thermally conductive fluid (740) substantially surrounds all of the coil (135) and the core (145), and the thermally conductive fluid (740) further fills the spatial gap (730) to increase convection.

22. The fluid-immersion type transformer (700) according to claim 11, further comprising a pump configured to circulate the aforementioned heat-conductive fluid (740).

23. A cooling system (500) for a high-power transformer system (100, 700) including a transformer (120), wherein the cooling system (500) A pump system (210) configured to deliver coolant (240), A cold plate (160) that physically contacts and transfers heat to one or more components (135, 145, 710) of the high-power transformer system, the cold plate (160) having an internal coolant flow path (260) configured to allow the coolant (240) to flow through the inside of the cold plate (160) A cooling system (500) comprising a cold plate (160) configured to remove heat generated in the transformer (120) of the high-power transformer system (100) via the coolant (240) sent from the pump system (210) to the cold plate.

24. The cooling system (500) according to claim 23, wherein the cold plate (160) is in physical contact with at least one of the coil (135) of the transformer (120) and the iron core (145) of the transformer (120) to transfer heat.

25. The cooling device (500) according to claim 23, further comprising a plurality of cold plates, each of which is in physical contact with at least one of the primary coils (135.1), secondary coils (135.2), or iron cores (145) of the transformer (120) to transfer heat.

26. The cooling device (500) according to claim 23, wherein the cold plate (160) is positioned between two or more of the primary coil (135.1), secondary coil (135.2), and iron core (145) of the transformer (120), and is in physical contact with and heat-transferred between them.

27. The cooling system (500) according to claim 23, wherein the cooling liquid (240) includes one or more of the following: water, distilled water, tap water, industrial water, chilled water, deionized water, brine, seawater, and water treated with antifreeze.

28. The cooling system (500) according to claim 23, wherein the coolant (240) comprises one or more of the following: an oil coolant, a hydrocarbon coolant, an organic liquid coolant, and a silicone coolant.

29. The cooling system (500) further comprises a thermal management enclosure (710) that houses and surrounds the transformer (120), The thermal management enclosure (710) is further configured to include a thermally conductive fluid (740), The thermal management enclosure (710) is thermally conductive, The cold plate (160) is in physical contact with and thermally coupled to the heat management housing (710). The cooling system (500) according to claim 23, wherein the cooling system (500) is configured and arranged to sequentially transfer the heat generated in the transformer (120) to the thermally conductive fluid (740), the thermal management housing (710), the cold plate (160), and the coolant (240).

30. The cooling system (500) according to claim 23, wherein the thermally conductive fluid (740) is oil.

31. The transformer (120) is configured such that (i) a pair of coils (135) of the transformer (120) and (ii) there is a spatial gap (730) between the coils (135) of the transformer and the core (145) of the transformer (120), The cooling system (500) according to claim 23, wherein the cooling system (500) further comprises the spatial gap (730), and the thermally conductive fluid (740) is configured to fill the spatial gap (730) and provide heat transfer.

32. The cooling system (500) according to claim 23, wherein the transformer (120) is suspended inside a thermal management enclosure (710) such that the thermally conductive fluid (740) is in physical and thermal contact with substantially all exposed surfaces of the transformer (120).

33. A power electronics building block (PEBB) (510) for a power converter (500), wherein the power electronics building block (510) is A first bridge converter for low voltage (915.1), A second bridge transducer for high voltage (915.2), A transformer (120) electrically coupling the first bridge converter (915.1) and the second bridge converter (915.2), A pump system (210) configured to deliver coolant (240), A cold plate (160) thermally coupled to the transformer (120), the cold plate (160) includes a coolant channel (260) for transporting the coolant (240) through the cold plate (160) and It is equipped with, A power electronics building block (510) in which heat generated in the transformer (120) is transferred to the environmental heat sink (295) by heat transfer from the transformer (120) to the cold plate (160) and by heat convection to the environmental heat sink (295) by the coolant (240).

34. The power electronics building block (510) according to claim 33, wherein the coolant (240) is an aqueous liquid.

35. The power electronics building block (510) according to claim 33, wherein the cold plate (160) is in physical direct contact with one or more heating elements (135, 145) of the transformer (120).

36. The transformer (120) is further housed in and surrounded by a thermal management enclosure (710), The thermal management enclosure (710) is configured to further contain a thermally conductive fluid (740), The thermal management enclosure (710) is thermally conductive, The cold plate (160) is in physical contact with and thermally coupled to the heat management housing (710). The power electronics building block (510) according to claim 33, wherein the cooling system (500) is configured and arranged to sequentially transfer heat generated in the transformer (120) to the thermally conductive fluid (740), the thermal management housing (710), the cold plate (160), and the coolant (240).

37. The power electronics building block (510) according to claim 36, wherein the thermally conductive fluid (740) is oil.

38. The power electronics building block (510) according to claim 36, wherein the transformer (120) is a high power density / high frequency transformer.

39. The power electronics building block (510) according to claim 38, wherein the transformer (120) has a winding ratio of K:N, where N > K, and the amount of heat generated by the transformer (120) with a K:N winding ratio is higher than the amount of heat generated by the transformer with a 1:1 winding ratio.

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