Liquid cooling power conversion system and liquid cooling power conversion method

Abstract

The invention provides a liquid-cooled power conversion system and a liquid-cooled power conversion method, and the system comprises a first non-stabilized power supply converter which is connected between an input voltage bus and an output voltage bus and comprises a plurality of first power switches; the second non-regulated power supply converter is connected between the input voltage bus and the output voltage bus, and the second non-regulated power supply converter comprises a plurality of second power switches; and the liquid cooling system is used for cooling the plurality of first power switches and the plurality of second power switches so as to realize current balanced distribution between the first non-stabilized power supply converter and the second non-stabilized power supply converter.

Description

Technical Field

[0001] This invention relates to a liquid-cooled power conversion system and a liquid-cooled power conversion method, and more particularly to a system and liquid-cooled power conversion method for achieving current sharing in a power conversion system comprising multiple parallel-connected unregulated power converters. Background Technology

[0002] With the continuous advancement of technology, modern data centers are equipped with a large number of high-performance processors, such as graphics processing units (GPUs). These processors are designed to handle high-intensity computing tasks such as artificial intelligence training, machine learning, and complex simulations. These GPUs, typically deployed in high-density racks, are able to quickly analyze and process massive amounts of data thanks to their superior parallel processing capabilities.

[0003] In data centers, processors are powered by power conversion systems. These systems connect the power grid to the processor, and their core function is to convert the AC voltage from the grid into the voltage required to drive the processor. Some power conversion systems use multiple power converters connected in parallel. The key objective of these systems is to ensure that each converter shares the load current evenly, or according to its design capacity, thus preventing any single unit from overloading. Current sharing is crucial for system reliability, operating efficiency, and lifespan. Various current sharing control methods have been developed, including voltage droop control, master-slave control, active current sharing control, average current mode control, and centralized control. In some applications, the processor is powered by multiple unregulated power converters connected in parallel. These unregulated converters lack a feedback loop to adjust the output according to load conditions. When multiple unregulated converters operate in parallel, slight differences in their output voltages can lead to uneven current distribution—for example, a converter with a higher output voltage may deliver more current, while a converter with a slightly lower voltage may not receive enough current or may not contribute any at all. This imbalance can cause the converter with the higher output voltage to overload, potentially leading to overheating or failure.

[0004] In practical operation, due to the temperature-dependent characteristics of the internal electronic components of power conversion systems, heat can cause current distribution imbalances in parallel-connected unregulated converters. Many internal components of converters (such as power switches) have temperature coefficients, and their electrical characteristics change with increasing temperature. For example, as temperature rises, the on-resistance of power switches increases. This leads to an increase in voltage drop at the same current, causing the converter to output less current when it heats up. In power conversion systems containing multiple unregulated converters, when one converter is more prone to overheating than others, its output voltage may drop, resulting in insufficient current supply and thus current distribution imbalances. Therefore, there is an urgent need for a solution that can achieve balanced current distribution in power systems with parallel-connected unregulated converters. This disclosure presents an innovative solution to address this need. Summary of the Invention

[0005] Through preferred embodiments, this disclosure generally solves or circumvents the current equalization distribution problem in the aforementioned unregulated converter power system, and achieves technical advantages. These embodiments provide a liquid-cooled power conversion system for achieving current sharing in a power conversion system comprising multiple parallel unregulated power converters.

[0006] According to one embodiment, a liquid-cooled power conversion system includes: a first unregulated power converter connected between an input voltage bus and an output voltage bus, wherein the first unregulated power converter includes a plurality of first power switches; a second unregulated power converter connected between the input voltage bus and the output voltage bus, wherein the second unregulated power converter includes a plurality of second power switches; and a liquid cooling system configured to cool the plurality of first power switches and the plurality of second power switches to achieve balanced current sharing between the first unregulated power converter and the second unregulated power converter.

[0007] According to another embodiment, a liquid-cooled power conversion method includes: providing a first unregulated power converter connected between an input voltage bus and an output voltage bus, wherein the first unregulated power converter includes a plurality of first power switches; providing a second unregulated power converter connected between the input voltage bus and the output voltage bus, wherein the second unregulated power converter includes a plurality of second power switches; and circulating liquid to cool the plurality of first power switches and the plurality of second power switches to achieve balanced current sharing between the first unregulated power converter and the second unregulated power converter.

[0008] According to yet another embodiment, a liquid-cooled power conversion method includes: providing a first unregulated power converter connected between an input voltage bus and an output voltage bus, wherein the first unregulated power converter includes a plurality of first power switches; providing a second unregulated power converter connected between the input voltage bus and the output voltage bus, wherein the second unregulated power converter includes a plurality of second power switches; circulating liquid through a plurality of first liquid pipes to cool the plurality of first power switches; circulating liquid through a plurality of second liquid pipes to cool the plurality of second power switches; and dynamically adjusting the first liquid flow rate in the plurality of first liquid pipes and the second liquid flow rate in the plurality of second liquid pipes to achieve balanced current sharing between the first unregulated power converter and the second unregulated power converter.

[0009] The features and technical advantages of this disclosure have been broadly summarized above to better understand the detailed description of the invention below. Additional features and advantages of this disclosure will be set forth below, forming the subject matter of the claims. Those skilled in the art will understand that the concepts and specific embodiments disclosed herein can be readily used as a basis for modifying or designing other structures or processes to achieve the same purpose as this disclosure. Those skilled in the art will also recognize that such equivalent constructions do not depart from the spirit and scope of this disclosure as defined by the appended claims. Attached Figure Description

[0010] By reading the detailed description of the exemplary embodiments below, those skilled in the art will understand the advantages and benefits described herein, as well as other advantages and benefits. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. In the drawings: Figure 1 A block diagram of a power conversion system according to various embodiments of the present disclosure is shown, the system including a plurality of unregulated power converters connected between an input voltage bus and an output voltage bus; Figure 2 Various embodiments according to this disclosure are illustrated. Figure 1 A schematic diagram of the unregulated power converter shown; Figure 3 A first implementation of a cooling arrangement for an unregulated power converter according to various embodiments of the present disclosure is shown; Figure 4 A second implementation of the cooling arrangement for an unregulated power converter according to various embodiments of the present disclosure is shown; Figure 5 A third implementation of the cooling arrangement for an unregulated power converter according to various embodiments of the present disclosure is shown; Figure 6 A fourth implementation of the cooling arrangement for an unregulated power converter according to various embodiments of the present disclosure is shown; Figure 7 A fifth implementation of the cooling arrangement for an unregulated power converter according to various embodiments of the present disclosure is shown; Figure 8 A sixth implementation of the cooling arrangement for an unregulated power converter according to various embodiments of the present disclosure is shown; Figure 9 A first implementation of cooling multiple unregulated LLC power converters according to various embodiments of the present disclosure is shown; Figure 10 A second implementation of cooling multiple unregulated LLC power converters according to various embodiments of the present disclosure is shown; Figure 11 A third implementation of cooling multiple unregulated LLC power converters according to various embodiments of the present disclosure is shown; Figure 12 A fourth implementation of cooling multiple unregulated LLC power converters according to various embodiments of the present disclosure is shown; Figure 13 A fifth implementation of cooling multiple unregulated LLC power converters according to various embodiments of the present disclosure is shown; Figure 14 A sixth implementation of cooling multiple unregulated LLC power converters according to various embodiments of the present disclosure is shown; Figure 15 Cooling according to various embodiments of the present disclosure is demonstrated. Figure 1 The flowchart of the power conversion system shown is as follows; Figure 16 This invention illustrates one implementation of cooling two unregulated LLC power converters according to various embodiments of the present disclosure; Figure 17 This invention illustrates one implementation of cooling multiple unregulated LLC power converters according to various embodiments of the present disclosure; and Figure 18 Cooling according to various embodiments of the present disclosure is demonstrated. Figure 16 The flowchart of the power conversion system shown is a method flowchart.

[0011] The numbers and symbols in the figures generally refer to the corresponding parts unless otherwise stated. The figures are drawn to clearly illustrate relevant aspects of the various embodiments and are not necessarily drawn to scale. Detailed Implementation

[0012] The manufacture and use of embodiments of this disclosure are discussed in detail below. However, it should be understood that the concepts disclosed herein can be implemented in various specific environments, and the specific embodiments described herein are merely illustrative and not intended to limit the scope of the claims. Furthermore, it should be understood that various changes, substitutions, and modifications can be made without departing from the spirit and scope of this disclosure as defined by the appended claims.

[0013] Furthermore, one or more features from one or more of the embodiments described below may be combined to create alternative embodiments not explicitly described herein, such combinations being considered within the scope of this disclosure. Therefore, the appended claims are intended to cover any such modifications or embodiments.

[0014] This disclosure will be described in the context of a preferred embodiment, namely a system and method for achieving current sharing in a power conversion system comprising multiple parallel unregulated power converters. However, this disclosure is also applicable to various power conversion systems. The embodiments will be described in detail below with reference to the accompanying drawings.

[0015] Figure 1 A block diagram of a power conversion system according to various embodiments of the present disclosure is shown, the system including a plurality of unregulated power converters connected between an input voltage bus and an output voltage bus. Figure 1 As shown, a first unregulated power converter 101 is connected between the input voltage bus VIN and the output voltage bus Vo. The first unregulated power converter 101 includes a plurality of first power switches. A second unregulated power converter 102 is connected between the input voltage bus VIN and the output voltage bus Vo. The second unregulated power converter 102 includes a plurality of second power switches. A third unregulated power converter 103 is connected between the input voltage bus VIN and the output voltage bus Vo. The third unregulated power converter 103 includes a plurality of third power switches. Figure 1 As indicated by the ellipsis, multiple unregulated power converters are disposed between the second unregulated power converter 102 and the third unregulated power converter 103.

[0016] A load (not shown) is connected to the output voltage bus Vo. In some embodiments, this load includes multiple machines in a cryptocurrency mining farm. Each machine may include multiple graphics processing units (GPUs), multiple application-specific integrated circuit (ASIC) chips, or any combination thereof.

[0017] In some embodiments, Figure 1 Each unregulated power converter shown is an inductor-inductor-capacitor (LLC) resonant converter configured to operate at a fixed duty cycle (e.g., 50%). In alternative embodiments, depending on different application and design requirements, Figure 1Each unregulated power converter shown can be implemented as an isolated power converter, such as a forward converter, a flying capacitor converter, a flyback converter, a full-bridge converter, a half-bridge converter, or any combination thereof.

[0018] During operation, the power switches of multiple unregulated power converters generate heat. A liquid cooling system is configured to cool the power switches to achieve balanced current sharing among the multiple unregulated power converters. Specifically, the power switch of each unregulated power converter is mounted on a corresponding heat sink. Heat is conducted from the power switch to the corresponding heat sink. The large surface area of ​​the heat sink facilitates efficient heat transfer. Multiple liquid pipes are connected to the heat sink. The heat sink and pipes constitute a cooling system. A pump pushes coolant (e.g., a suitable liquid like water) through this system, flowing through the heat sink. Heat from the power switches is absorbed by the coolant. The heated coolant then flows through the pipes to the heat sink, where it is cooled. Once the liquid has cooled in the heat sink, it is pumped back to the heat sink to absorb more heat, and so on. Liquids have a higher heat capacity than air, making them more efficient at absorbing and transferring heat.

[0019] During operation, the cooling system maintains a uniform temperature across the power switches of multiple unregulated power converters. This stable temperature ensures that the power switches have identical on-resistance, resulting in the same voltage drop for the same current. These matched voltage drops facilitate current sharing among the multiple unregulated power converters.

[0020] Figure 2 Various embodiments of the present disclosure are shown Figure 1 The diagram shows a schematic of an unregulated power converter. In some embodiments, the unregulated power converter (e.g., 101) is implemented as an LLC resonant converter. Figure 2 As shown, the LLC resonant converter includes a switching network 202, a resonant tank circuit 204, a transformer 212, a rectifier 214, and an output filter 216. Figure 2 As shown, the switching network 202, resonant tank circuit 204, transformer 212, rectifier 214 and output filter 216 are coupled to each other and cascaded between the input voltage bus VIN and the output voltage bus Vo.

[0021] Switching network 202 includes four switching elements, namely Q11, Q12, Q13, and Q14. Throughout the description, switching network 202 may also be referred to as the primary switching network.

[0022] like Figure 2As shown, the first pair of switching elements Q11 and Q12 are connected in series between the input voltage bus VIN and the primary ground. The second pair of switching elements Q13 and Q14 are connected in series between the input voltage bus VIN and the primary ground. The common node of switching elements Q11 and Q12 is connected to the first input terminal T1 of the resonant tank circuit 204. Similarly, the common node of switching elements Q13 and Q14 is connected to the second input terminal T2 of the resonant tank circuit 204.

[0023] Figure 2 The resonant tank circuit 204 is further illustrated, connecting the switching network 202 and the transformer 212. The resonant tank circuit 204 consists of a series resonant inductor Lr, a series resonant capacitor Cr, and a parallel inductor Lm. (As shown...) Figure 2 As shown, the series resonant inductor Lr and the series resonant capacitor Cr are connected in series and further connected to the primary side of transformer 212.

[0024] It should be noted that, although Figure 2 The series resonant inductor Lr is shown as a separate component, but it can be replaced by the leakage inductance of transformer 212. In other words, the leakage inductance (not shown) can function as the series resonant inductor Lr.

[0025] It should also be noted that, although Figure 2 The illustration shows the resonant tank circuit located on the primary side of the LLC resonant converter, but this is merely an example. Those skilled in the art will recognize many variations, alternatives, and modifications. For example, the resonant tank circuit can be located on the secondary side. Furthermore, the resonant tank circuit can be located on both sides of transformer 212.

[0026] Transformer 212 has a primary winding NP and a secondary winding NS. For example... Figure 2 As shown, the primary winding is connected to terminals T3 and T4 of the resonant slot circuit 204. The secondary winding is connected to the output of the LLC resonant converter via rectifier 214, which is a full-bridge rectifier comprising switches Q21, Q22, Q23, and Q24. Throughout the description, rectifier 214 is also referred to as the secondary switching network.

[0027] like Figure 2 As shown, switches Q21 and Q22 are connected in series and further coupled between the two ends of the output capacitor Co. Switches Q23 and Q24 are connected in series and further coupled between the two ends of the output capacitor Co. The common node T5 of switches Q21 and Q22 is coupled to the first end of the secondary winding of transformer 212. Similarly, the common node T6 of switches Q23 and Q24 is coupled to the second end of the secondary winding of transformer 212.

[0028] It should be noted that, Figure 2The transformer structure shown is merely an example. Those skilled in the art will recognize many alternatives, variations, and modifications. For example, the secondary side of transformer 212 can be a transformer winding with a center tap. Therefore, the secondary side can employ a synchronous rectifier consisting of two switching elements. The operating principle of a synchronous rectifier coupled to a transformer winding with a center tap is well known, and therefore will not be discussed further in detail here to avoid repetition.

[0029] It should also be noted that the power topology of LLC resonant converters can be applied not only to... Figure 2 The rectifier shown can also be applied to other secondary configurations, such as voltage doubler rectifiers, current doubler rectifiers, and any combination thereof.

[0030] During operation, the LLC resonant converter may exhibit unity system gain when its switching frequency equals the resonant frequency of the resonant tank circuit. Conversely, when the switching frequency is higher than the resonant frequency, the system gain is lower.

[0031] Back Figure 1 The power conversion system comprises multiple unregulated power converters with similar operating principles and cooling mechanisms. For simplicity, Figure 3-8 Only two unregulated power converters are depicted to demonstrate how the cooling system is designed to maintain a uniform temperature across all unregulated power converters.

[0032] Figure 3 A first implementation of a cooling arrangement for an unregulated power converter according to various embodiments of the present disclosure is shown. For example... Figure 3 As shown, a plurality of first power switches 331 of the first unregulated power converter 101 are mounted on the first heat sink 341. A plurality of second power switches 332 of the second unregulated power converter 102 are mounted on the second heat sink 342. A plurality of liquid conduits connect the first heat sink 341 and the second heat sink 342. The plurality of liquid conduits include a first liquid conduit 321 and a second liquid conduit 322, through which liquid flows from the second heat sink 342 to the first heat sink 341 via the first liquid conduit 321, and from the first heat sink 341 to the second heat sink 342 via the second liquid conduit 322.

[0033] In some embodiments, cooling efficiency is further improved by arranging the liquid conduits in alignment with the positions of specific power switches within the radiator. A portion of a first liquid conduit 321 is located within the first radiator 341 and below the left-hand power switch on the first radiator 341. As shown by the dashed line above the left-hand power switch on the first radiator 341, the centerline of this portion of the first liquid conduit 321 within the first radiator 341 is aligned with the centerline of the left-hand power switch on the first radiator 341. Similarly, a portion of a second liquid conduit 322 is located within the first radiator 341 and below the right-hand power switch on the first radiator 341. As shown by the dashed line above the right-hand power switch on the first radiator 341, the centerline of this portion of the second liquid conduit 322 within the first radiator 341 is aligned with the centerline of the right-hand power switch on the first radiator 341.

[0034] A portion of the second liquid conduit 322 is located within the second radiator 342, below the left-hand power switch on the second radiator 342. As shown by the dashed line above the left-hand power switch on the second radiator 342, the center line of this portion of the second liquid conduit 322 within the second radiator 342 is aligned with the center line of the left-hand power switch on the second radiator 342. A portion of the first liquid conduit 321 is located within the second radiator 342, below the right-hand power switch on the second radiator 342. As shown by the dashed line above the right-hand power switch on the second radiator 342, the center line of this portion of the first liquid conduit 321 within the second radiator 342 is aligned with the center line of the right-hand power switch on the second radiator 342.

[0035] One advantage of aligning the piping with the power switch is that this arrangement ensures better thermal coupling between the coolant and the power switch, thereby improving heat transfer and overall cooling performance.

[0036] During operation, coolant circulates between the first radiator 341 and the second radiator 342 through liquid pipes 321 and 322. This circulation establishes thermal coupling between the two unregulated power converters, resulting in substantially uniform temperature between the power switches of the two unregulated power converters. By maintaining similar operating temperatures, the on-resistance of the power switches is balanced, which in turn helps to achieve balanced current distribution between the first unregulated power converter 101 and the second unregulated power converter 102.

[0037] It should be noted that, Figure 3 Only two unregulated power converters are shown in a single power conversion system, which may contain hundreds of such unregulated power converters. The number of unregulated power converters shown herein is merely for the purpose of clearly illustrating the innovative aspects of the various embodiments. The invention is not limited to any particular number of unregulated power converters.

[0038] Figure 4 A second implementation of the cooling arrangement for an unregulated power converter according to various embodiments of the present disclosure is shown. For example... Figure 4 As shown, a first unregulated power converter 101 is encapsulated within a first power module 351. The first power module 351 is mounted on a first heat sink 341. In some embodiments, a good thermal interface is provided between the first power module 351 and the first heat sink 341, such that the temperature of the first power module 351 is substantially similar to the temperature of the first heat sink 341. Furthermore, the power switch of the first unregulated power converter 101 is directly mounted at the bottom of the first power module 351. The power switch achieves good thermal coupling with the first heat sink 341 through the bottom of the first power module 351. In other words, the temperature of the power switch in the first power module 351 is substantially similar to the temperature of the first heat sink 341.

[0039] The second unregulated power converter 102 is encapsulated within the second power module 352. The second power module 352 is mounted on the second heat sink 342. In some embodiments, a good thermal interface is provided between the second power module 352 and the second heat sink 342, such that the temperature of the second power module 352 is substantially similar to the temperature of the second heat sink 342. Furthermore, the power switch of the second unregulated power converter 102 is directly mounted at the bottom of the second power module 352. The power switch achieves good thermal coupling with the second heat sink 342 through the bottom of the second power module 352. In other words, the temperature of the power switch in the second power module 352 is substantially similar to the temperature of the second heat sink 342.

[0040] Multiple liquid conduits are connected between the first radiator 341 and the second radiator 342. The multiple liquid conduits include a first liquid conduit 321 through which liquid flows from the second radiator 342 to the first radiator 341; and a second liquid conduit 322 through which liquid flows from the first radiator 341 to the second radiator 342.

[0041] During operation, coolant circulates between the first radiator 341 and the second radiator 342 through liquid pipes 321 and 322. This circulation establishes thermal coupling between the two unregulated power converters, causing the temperature between the power switches of the two unregulated power converters to remain substantially consistent. By maintaining similar operating temperatures, the on-resistance of the power switches is balanced, which in turn helps to achieve a balanced current distribution between the first unregulated power converter 101 and the second unregulated power converter 102.

[0042] It should be noted that, Figure 4Only two unregulated power converters are shown in a single power conversion system, while such a system may contain hundreds of such unregulated power converters. The number of unregulated power converters shown herein is merely for the purpose of clearly illustrating the innovative aspects of the various embodiments. The invention is not limited to any particular number of unregulated power converters.

[0043] A finger-shaped heatsink is a heat dissipation device designed with multiple elongated fins resembling fingers. It provides a large surface area for heat dissipation from electronic components, effectively dissipating the heat generated. Compared to flat heatsinks, this finger-shaped design significantly increases the heat dissipation surface area, making heat dissipation more efficient. Finger-shaped heatsinks are typically made of suitable materials such as aluminum or copper. Figure 5-8 This demonstrates a configuration where the heating element is mounted on a finger-shaped heatsink, with liquid channels connected to it. During operation, the finger-shaped heatsink-based cooling system is designed to maintain a uniform temperature across all unregulated power converters.

[0044] Figure 5 A third embodiment of the cooling arrangement for an unregulated power converter according to various embodiments of this disclosure is shown. For example... Figure 5 As shown, a plurality of first power switches 331 of the first unregulated power converter 101 are mounted on the first finger-shaped heat sink 361. A plurality of second power switches 332 of the second unregulated power converter 102 are mounted on the second finger-shaped heat sink 362. A plurality of liquid conduits connect the first finger-shaped heat sink 361 and the second finger-shaped heat sink 362. These liquid conduits include a first liquid conduit 321 through which coolant flows from the second finger-shaped heat sink 362 to the first finger-shaped heat sink 361; and a second liquid conduit 322 through which coolant flows from the first finger-shaped heat sink 361 to the second finger-shaped heat sink 362.

[0045] In some embodiments, such as Figure 5 As shown by the dotted lines, the arrangement of the liquid pipes within the radiator is similar to that described above. Figure 3 Similar to the above. Specifically, portions of the liquid conduit are located below the respective power switches and are arranged roughly along the centerline of these switches, thereby providing better thermal coupling and superior cooling performance.

[0046] During operation, coolant circulates between the first finger-shaped heat sink 361 and the second finger-shaped heat sink 362 through liquid pipes 321 and 322. This circulation establishes thermal coupling between the two unregulated power converters, causing the temperature between the power switches of the two unregulated power converters to remain substantially consistent. By maintaining similar operating temperatures, the on-resistance of the power switches is balanced, which in turn helps to achieve a balanced current distribution between the first unregulated power converter 101 and the second unregulated power converter 102.

[0047] It should be understood that, in conjunction with the preceding appendix Figure 1 Sample, Figure 5 The number of converters shown is for illustrative purposes only and is not intended to limit the scope of this disclosure.

[0048] Figure 6 A fourth embodiment of the cooling arrangement for an unregulated power converter according to various embodiments of the present disclosure is shown. For example... Figure 6 As shown, a first unregulated power converter 101 is packaged within a first power module 351. The first power module 351 is mounted on a first finger-shaped heatsink 361. A second unregulated power converter 102 is packaged within a second power module 352. The second power module 352 is mounted on a second finger-shaped heatsink 362. The thermal configuration of the first power module 351 and the second power module 352 is as described above. Figure 4 The discussion is similar, so it will not be described in detail here.

[0049] Multiple liquid conduits are connected between the first finger radiator 361 and the second finger radiator 362. These liquid conduits include a first liquid conduit 321 through which coolant flows from the second finger radiator 362 to the first finger radiator 361; and a second liquid conduit 322 through which coolant flows from the first finger radiator 361 to the second finger radiator 362.

[0050] During operation, coolant circulates between the first finger-shaped heat sink 361 and the second finger-shaped heat sink 362 through liquid pipes 321 and 322. This circulation establishes thermal coupling between the two unregulated power converters, causing the temperature between the power switches of the two unregulated power converters to remain substantially consistent. By maintaining similar operating temperatures, the on-resistance of the power switches is balanced, which in turn helps to achieve a balanced current distribution between the first unregulated power converter 101 and the second unregulated power converter 102.

[0051] It should be understood that, in conjunction with the preceding appendix Figure 1 Sample, Figure 6 The number of converters shown is for illustrative purposes only and is not intended to limit the scope of this disclosure.

[0052] Figure 7 A fifth embodiment of the cooling arrangement for an unregulated power converter according to various embodiments of this disclosure is shown. For example... Figure 7As shown, a plurality of first power switches 331 of the first unregulated power converter 101 and a plurality of second power switches 332 of the second unregulated power converter 102 are mounted on a finger-shaped heat sink 371. A plurality of liquid conduits are connected to the finger-shaped heat sink 371. These liquid conduits include a first liquid conduit 321 through which liquid flows from the right side to the left side of the finger-shaped heat sink 371; and a second liquid conduit 322 through which liquid flows from the left side to the right side of the finger-shaped heat sink 371.

[0053] In some embodiments, such as Figure 7 As shown by the dotted lines, the arrangement of the liquid pipes within the radiator is similar to that described above. Figure 3 Similar to the above. Specifically, portions of the liquid conduit are located below the respective power switches and are arranged roughly along the centerline of these switches, thereby providing better thermal coupling and superior cooling performance.

[0054] During operation, coolant circulates between the right and left sides of the finger-shaped radiator 371 via liquid pipes 321 and 322. This circulation establishes thermal coupling between the two unregulated power converters, causing the temperature between the power switches of the two unregulated power converters to remain substantially consistent. By maintaining similar operating temperatures, the on-resistance of the power switches is balanced, which in turn helps to achieve a balanced current distribution between the first unregulated power converter 101 and the second unregulated power converter 102.

[0055] It should be understood that, in conjunction with the preceding appendix Figure 1 Sample, Figure 7 The number of converters shown is for illustrative purposes only and is not intended to limit the scope of this disclosure.

[0056] Figure 8 A sixth embodiment of the cooling arrangement for an unregulated power converter according to various embodiments of the present disclosure is shown. For example... Figure 8 As shown, a first unregulated power converter 101 is packaged in a first power module 351. A second unregulated power converter 102 is packaged in a second power module 352. The first power module 351 and the second power module 352 are mounted on a finger-shaped heatsink 371. The thermal configuration of the first power module 351 and the second power module 352 is as described above. Figure 4 The discussion is similar, so it will not be described in detail here.

[0057] Multiple liquid conduits are connected to the finger-shaped radiator 371. These liquid conduits include a first liquid conduit 321 through which liquid flows from the right side to the left side of the finger-shaped radiator 371; and a second liquid conduit 322 through which liquid flows from the left side to the right side of the finger-shaped radiator 371.

[0058] During operation, coolant circulates between the right and left sides of the finger-shaped radiator 371 via liquid pipes 321 and 322. This circulation establishes thermal coupling between the two unregulated power converters, causing the temperature between the power switches of the two unregulated power converters to remain substantially consistent. By maintaining similar operating temperatures, the on-resistance of the power switches is balanced, which in turn helps to achieve a balanced current distribution between the first unregulated power converter 101 and the second unregulated power converter 102.

[0059] It should be understood that, in conjunction with the preceding appendix Figure 1 Sample, Figure 8 The number of converters shown is given for illustrative purposes only and is not intended to limit the scope of this disclosure.

[0060] Back Figure 2 The first unregulated power converter is implemented as a first LLC resonant converter, which includes multiple first primary switches Q11, Q12, Q13 and Q14, a first resonant tank composed of Cr and Lr, a first transformer, and multiple first primary switches Q21, Q22, Q23 and Q24. The second unregulated power converter is implemented as a second LLC resonant converter, which includes multiple second primary switches Q11, Q12, Q13 and Q14, a second resonant tank composed of Cr and Lr, a second transformer, and multiple second secondary switches Q21, Q22, Q23 and Q24. Figure 9-14 It demonstrates how the cooling system is designed to ensure that the temperature of all unregulated LLC resonant converters remains uniform.

[0061] Figure 9 This paper illustrates a first implementation of cooling multiple unregulated LLC power converters according to various embodiments of the present disclosure. Multiple first primary switches, a first resonant tank, a first transformer, and multiple first-stage switches are mounted on a first heat sink 301. Multiple second primary switches, a second resonant tank, a second transformer, and multiple second-stage switches are mounted on a second heat sink 302. The heat-generating components of other unregulated LLC power converters are arranged in a similar manner. For example, the heat-generating component of the Nth unregulated LLC power converter is mounted on heat sink 303.

[0062] In some embodiments, radiators 301, 302, and 303 are insulated metal substrate type radiators, on which a single thermally conductive bonding layer is formed. All heat-generating components mounted on a given radiator are thermally coupled to each other through this single bonding layer, thereby promoting uniform heat dissipation and improving cooling performance.

[0063] Multiple liquid pipes are connected to the radiator. For example... Figure 9As indicated by the arrows, the liquid circulates through multiple liquid pipes in the radiator to ensure that the temperature of the unregulated LLC power converter remains uniform.

[0064] like Figure 9 As shown, the first liquid pipe 901 of the plurality of liquid pipes is equidistant from two adjacent first primary switches (e.g., Q11 and Q13, or Q12 and Q14). The second liquid pipe 902 of the plurality of liquid pipes is equidistant from two adjacent first primary switches (e.g., Q21 and Q23, or Q22 and Q24). It should be noted that an interconnecting liquid pipe (not shown) is placed in the radiator 303. This interconnecting liquid pipe is used to connect the first liquid pipe 901 and the second liquid pipe 902.

[0065] During operation, the power switches are cooled via the aforementioned liquid pipes and insulated metal substrate heat sinks, ensuring that the operating temperature of the power switches in multiple unregulated LLC power converters remains at a substantially uniform level. This uniform temperature results in similar on-resistance of the power switches, which in turn facilitates balanced current distribution among the multiple unregulated LLC power converters. This improves the overall system reliability, reduces the risk of overloading individual converters, and enhances efficiency in high-power applications.

[0066] Figure 10 A second implementation of cooling multiple unregulated LLC power converters according to various embodiments of the present disclosure is shown. Multiple first primary switches, a first resonant slot, and multiple first secondary switches are mounted on a first heat sink 301. A first transformer is mounted on a first transformer heat sink 31. Multiple second primary switches, a second resonant slot, and multiple second secondary switches are mounted on a second heat sink 302. A second transformer is mounted on a second transformer heat sink 32. The heat-generating components of other unregulated LLC power converters are arranged in a similar manner. For example, the primary switches, resonant slots, and secondary switches of the Nth unregulated LLC power converter are mounted on a heat sink 303. The transformer of the Nth unregulated LLC power converter is mounted on a transformer heat sink 33.

[0067] Liquid pipes 901 and 902 are connected to radiators 301, 302, and 303. For example... Figure 10 As indicated by the arrows, liquid circulates within the radiator through liquid pipes 901 and 902 to ensure that the temperature of these heat-generating components remains uniform. Liquid pipes 903 and 904 are connected to transformer radiators 31, 32, and 33. Figure 10 As indicated by the arrows, liquid circulates in the transformer radiators through liquid pipes 903 and 904 to ensure that the temperature of these transformers is maintained at a second uniform temperature. In some embodiments, the first uniform temperature is equal to the second uniform temperature.

[0068] The positioning of liquid pipelines 901 and 902 is the same as above. Figure 9 Similar to what has been described. Specifically, the liquid conduit (e.g., liquid conduit 901) is equidistant from two adjacent switches (e.g., Q11 and Q13), thereby providing better heat dissipation. Furthermore, as... Figure 10 As shown by the dashed lines, the left edge of liquid pipe 903 is aligned with the left edge of the transformer. The right edge of liquid pipe 904 is aligned with the right edge of the transformer. This arrangement of liquid pipes can further improve cooling performance.

[0069] Figure 11 A third implementation of cooling multiple unregulated LLC power converters according to various embodiments of the present disclosure is shown. Figure 11 The cooling arrangement shown is similar to Figure 10 Similar to the example shown, the difference lies in that the liquid pipe 903 passes through the transformer body, allowing the coolant to circulate inside the transformer. During operation, this circulation maintains a substantially uniform temperature throughout the transformer, thereby enhancing thermal stability and overall performance.

[0070] Figure 12 A fourth implementation of cooling multiple unregulated LLC power converters according to various embodiments of the present disclosure is shown. Figure 12 The cooling arrangement shown is similar to Figure 10 Similar to the example shown, the difference is that the primary and secondary switches are mounted on two different heat sinks. (See example...) Figure 12 As shown, the primary switch of the first unregulated LLC power converter and the resonant tank circuit composed of Cr and Lr are mounted on heat sink 301. The secondary switch of the first unregulated LLC power converter is mounted on heat sink 311. Similarly, the primary switch of the second unregulated LLC power converter and the resonant tank circuit composed of Cr and Lr are mounted on heat sink 302. The secondary switch of the second unregulated LLC power converter is mounted on heat sink 312. The primary switch of the Nth unregulated LLC power converter and the resonant tank circuit composed of Cr and Lr are mounted on heat sink 303. The secondary switch of the Nth unregulated LLC power converter is mounted on heat sink 313.

[0071] During operation, liquid circulates through liquid pipes 901 and 902 in radiators 301, 302, and 303 to maintain a first uniform temperature throughout these heat-generating components. Liquid circulates through liquid pipes 905 and 906 in radiators 311, 312, and 313 to maintain a second uniform temperature throughout these heat-generating components. Liquid circulates through liquid pipes 903 and 904 in radiators 31, 32, and 33 to maintain a third uniform temperature throughout these heat-generating components. In some embodiments, the first uniform temperature is equal to both the second and third uniform temperatures.

[0072] Figure 13 A fifth implementation of cooling multiple unregulated LLC power converters according to various embodiments of the present disclosure is shown. Figure 13 The cooling arrangement shown is similar to Figure 12 Similar to the example shown, the difference lies in that the liquid pipe 903 passes through the transformer body, allowing the coolant to circulate inside the transformer. During operation, this circulation maintains a substantially uniform temperature throughout the transformer, thereby enhancing thermal stability and overall performance.

[0073] Figure 14 A sixth implementation of cooling multiple unregulated LLC power converters according to various embodiments of this disclosure is shown. The heat-generating component of the first unregulated power converter is mounted on a first heat sink 301. The heat-generating component of the second unregulated power converter is mounted on a second heat sink 302. The heat-generating component of the Nth unregulated power converter is mounted on a third heat sink 303. The multiple unregulated power converters and their associated heat sinks are immersed in liquid within a container 1100. The liquid within container 1100 is used to cool the power switches of the multiple unregulated power converters to achieve balanced current distribution.

[0074] Figure 15 Various embodiments of the present disclosure are illustrated. Figure 1 The flowchart shown illustrates the method for cooling the power conversion system. Figure 15 The flowchart shown is merely an example and should not unduly limit the scope of the claims. Those skilled in the art will recognize many variations, alternatives, and modifications. For example, Figure 15 The steps shown can be added, deleted, replaced, rearranged, and repeated.

[0075] In step 1502, a first unregulated power converter is provided. This first unregulated power converter is connected between the input voltage bus and the output voltage bus, and includes a plurality of first power switches.

[0076] In step 1504, a second unregulated power converter is provided. This second unregulated power converter is connected between the input voltage bus and the output voltage bus, and includes a plurality of second power switches.

[0077] In step 1506, the liquid is circulated to cool the multiple first power switches and multiple second power switches, thereby achieving a balanced current distribution between the first unregulated power converter and the second unregulated power converter.

[0078] The method further includes: configuring a first unregulated power converter and a second unregulated power converter to operate with the same fixed duty cycle; mounting a plurality of first power switches on a first heat sink; mounting a plurality of second power switches on a second heat sink; and circulating liquid in the first heat sink and the second heat sink through a plurality of liquid pipes connected between the first heat sink and the second heat sink.

[0079] The method further includes: configuring a first unregulated power converter and a second unregulated power converter to operate at the same fixed duty cycle; encapsulating the first unregulated power converter in a first power module; mounting the first power module on a first heat sink; encapsulating the second unregulated power converter in a second power module; mounting the second power module on a second heat sink; and circulating liquid in the first heat sink and the second heat sink through a plurality of liquid pipes connected between the first heat sink and the second heat sink.

[0080] Figure 16 This invention illustrates an implementation of cooling two unregulated LLC power converters according to various embodiments of the present disclosure. The power conversion system includes a first unregulated power converter and a second unregulated power converter. Each of the two unregulated power converters can be implemented as an LLC resonant converter configured to operate at a fixed duty cycle (e.g., 50%). The two unregulated power converters are connected in parallel to provide a combined output current to the load.

[0081] The first unregulated power converter includes multiple heat-generating components, including a primary power switch, a resonant tank circuit, a transformer, and a secondary power switch. The heat-generating components of the first unregulated power converter are mounted on a first heat sink 301. The first heat sink 301 is thermally coupled to liquid cooling pipes 1601 and 1602, which are configured to circulate coolant at a first controllable flow rate. Similarly, the second unregulated power converter includes multiple heat-generating components, including a primary power switch, a resonant tank circuit, a transformer, and a secondary power switch. The heat-generating components of the second unregulated power converter are mounted on a second heat sink 302. The second heat sink 302 is thermally coupled to liquid cooling pipes 1603 and 1604, which are configured to circulate coolant at a second controllable flow rate.

[0082] During operation, the current sensing circuit detects a first current flowing through the first unregulated power converter and a second current flowing through the second unregulated power converter. The control circuit compares the magnitudes of the first and second currents and generates a flow control signal to adjust the liquid flow rate through liquid cooling pipes 1601 and 1602, as well as the liquid flow rate through liquid cooling pipes 1603 and 1604.

[0083] In one operating scenario, if the detected first current is greater than the second current, the control circuit reduces the flow rate in liquid cooling pipes 1601 and 1602, thereby reducing the cooling efficiency of the first heatsink 301 and increasing the operating temperature of the power switch in the first unregulated power converter. The increased temperature leads to an increase in the on-resistance of the power switch in the first unregulated power converter, thus reducing the current drawn by the first unregulated power converter. Simultaneously, the flow rate in liquid cooling pipes 1603 and 1604 increases, reducing the temperature and on-resistance of the power switch in the second unregulated power converter, thereby increasing the current drawn by the second unregulated power converter. This coordinated regulation balances the current between the two unregulated power converters.

[0084] Conversely, if the second current is greater than the first current, the control circuit will increase the flow rate in liquid cooling pipes 1601 and 1602 and decrease the flow rate in liquid cooling pipes 1603 and 1604, thereby shifting the current distribution in the opposite direction until a balanced current distribution is achieved.

[0085] Figure 16 An advantageous feature of the illustrated cooling configuration is that, through adaptive control of the liquid flow rate, the unregulated power converter can achieve substantially equal current distribution across a range of load conditions. More specifically, the disclosed method and system utilize the inherent thermal characteristics of the power switch and the dynamic characteristics of liquid cooling to achieve passive current distribution, eliminating the need for complex active current distribution circuitry. This system is particularly beneficial for high-power applications that already employ liquid cooling, such as data center power supplies, electric vehicle chargers, or renewable energy conversion systems.

[0086] Figure 17 This invention illustrates one implementation of cooling multiple unregulated LLC power converters according to various embodiments of the present disclosure. The power conversion system includes multiple unregulated power converters connected in parallel between an input voltage bus and an output voltage bus.

[0087] Each of the multiple converters is configured to operate with the same fixed duty cycle, such as 50% duty cycle in an LLC resonant topology. Each unregulated power converter includes a primary power switch, a resonant tank circuit, a transformer, and a secondary power switch, all mounted on a corresponding heatsink, each of which is connected to a liquid-cooled conduit with a controllable fluid flow rate.

[0088] A current sensing circuit is provided to measure the individual current flowing through each unregulated power converter. A control circuit receives these current measurements and determines the current imbalance between the converters. To resolve the imbalance, the control circuit identifies the converter with the highest current and the converter with the lowest current. It reduces the coolant flow rate in the converter with the highest current, thereby increasing its switching temperature and on-resistance; simultaneously, it increases the coolant flow rate in the converter with the lowest current, thereby reducing its switching temperature and on-resistance.

[0089] This adjustment process is repeated. After adjusting the coolant flow rate of the identified converters with the highest and lowest current, the system reassesses the current distribution among all converters. Then, new converters with the highest and lowest current are identified, and the same adjustment process is applied. This iterative process continues until the difference between the maximum and minimum current of the converters decreases below a predetermined threshold, thus achieving a basically balanced current distribution among all converters.

[0090] By employing this iterative balancing strategy, the power conversion system can dynamically adapt to load changes, device variations, or thermal drift without requiring centralized duty cycle control or droop compensation circuitry. Since liquid cooling is already commonly used in high-power conversion systems, such as large data center power supplies, electric vehicle charging stations, or renewable energy inverters, the disclosed method provides a low-cost and reliable mechanism for current balancing among multiple parallel unregulated converters.

[0091] Figure 18 Various embodiments of the present disclosure are illustrated. Figure 16 The flowchart shown illustrates the cooling method for the power conversion system. Figure 18 The flowchart shown is merely an example and should not unduly limit the scope of the claims. Those skilled in the art will recognize many variations, alternatives, and modifications. For example, Figure 18 The steps shown can be added, deleted, replaced, rearranged, and repeated.

[0092] In step 1802, a first unregulated power converter is provided. This first unregulated power converter is connected between the input voltage bus and the output voltage bus, and includes a plurality of first power switches.

[0093] In step 1804, a second unregulated power converter is provided. This second unregulated power converter is connected between the input voltage bus and the output voltage bus, and includes a plurality of second power switches.

[0094] In step 1806, liquid is circulated through multiple first liquid pipes to cool multiple first power switches.

[0095] In step 1808, liquid is circulated through multiple second liquid pipes to cool multiple second power switches.

[0096] In step 1810, the first liquid flow rate in the multiple first liquid pipes and the second liquid flow rate in the multiple second liquid pipes are dynamically adjusted to achieve a balanced current distribution between the first unregulated power converter and the second unregulated power converter.

[0097] The method further includes: configuring a first unregulated power converter and a second unregulated power converter to operate with the same fixed duty cycle; mounting a plurality of first power switches on a first heat sink; mounting a plurality of second power switches on a second heat sink; detecting a first current flowing through the first unregulated power converter and a second current flowing through the second unregulated power converter; in response to a first current level being greater than a second current level, reducing a first liquid flow rate in a plurality of first liquid channels to increase the on-resistance of the plurality of first power switches and increasing a second liquid flow rate in a plurality of second liquid channels to decrease the on-resistance of the plurality of second power switches, thereby achieving current equalization between the first unregulated power converter and the second unregulated power converter; and in response to a second current level being greater than a first current level, increasing a first liquid flow rate in a plurality of first liquid channels to decrease the on-resistance of the plurality of first power switches and decreasing a second liquid flow rate in a plurality of second liquid channels to increase the on-resistance of the plurality of second power switches, thereby achieving current equalization between the first unregulated power converter and the second unregulated power converter.

[0098] The method further includes: providing a plurality of unregulated power converters connected between an input voltage bus and an output voltage bus, wherein the plurality of unregulated power converters includes a first unregulated power converter and a second unregulated power converter, and wherein each of the plurality of unregulated power converters includes a plurality of power switches; configuring the plurality of unregulated power converters to operate with the same fixed duty cycle; mounting the power switch of one of the plurality of unregulated power converters on a corresponding heat sink; detecting the current flowing through the plurality of unregulated power converters; identifying the unregulated power converter with the maximum current and the unregulated power converter with the minimum current; reducing the liquid flow rate in a plurality of liquid pipes connected to the unregulated power converter with the maximum current and increasing the liquid flow rate in a plurality of liquid pipes connected to the unregulated power converter with the minimum current, thereby achieving current equalization.

[0099] Although embodiments of the present disclosure and their advantages have been described in detail, it should be understood that various changes, substitutions and alterations may be made herein without departing from the spirit and scope of the present disclosure as defined by the appended claims.

[0100] Furthermore, the scope of this application is not intended to be limited to the specific embodiments of the processes, machines, manufactures, material compositions, means, methods, and steps described in the specification. Those skilled in the art will readily understand from the content of this disclosure that existing or later-developed processes, machines, manufactures, material compositions, means, methods, or steps that perform substantially the same function or achieve substantially the same results as the corresponding embodiments described herein can be utilized in accordance with this disclosure. Therefore, the appended claims are intended to include such processes, machines, manufactures, material compositions, means, methods, or steps within their scope.

Claims

1. A liquid-cooled power conversion system, comprising: A first unregulated power converter is connected between an input voltage bus and an output voltage bus. The first unregulated power converter includes a plurality of first power switches. The second unregulated power converter is connected between the input voltage bus and the output voltage bus, and the second unregulated power converter includes a plurality of second power switches; A liquid cooling system is used to cool multiple first power switches and multiple second power switches to achieve balanced current distribution between the first unregulated power converter and the second unregulated power converter.

2. The system according to claim 1, comprising: A first heat sink, on which multiple first power switches are mounted; A second heat sink, on which multiple second power switches are mounted; as well as Multiple liquid pipes are connected between the first radiator and the second radiator, and liquid flows through the first radiator and the second radiator through the multiple liquid pipes.

3. The liquid-cooled power conversion system according to claim 1, comprising: The first heat sink, wherein the first unregulated power converter is encapsulated in the first power module, and the first power module is mounted on the first heat sink; The second heat sink, wherein the second unregulated power converter is packaged in the second power module, and the second power module is mounted on the second heat sink; and Multiple liquid pipes are connected between the first radiator and the second radiator, wherein liquid circulates between the first radiator and the second radiator through the multiple liquid pipes.

4. The liquid-cooled power conversion system according to claim 1, comprising: A first finger-shaped heat sink, wherein the plurality of first power switches are mounted on the first finger-shaped heat sink; A second finger-shaped heat sink, wherein the plurality of second power switches are mounted on the second finger-shaped heat sink; and Multiple liquid pipes are connected between the first finger-shaped radiator and the second finger-shaped radiator, wherein liquid circulates in the first finger-shaped radiator and the second finger-shaped radiator through the multiple liquid pipes.

5. The liquid-cooled power conversion system according to claim 1, comprising: The first finger-shaped heat sink, wherein the first unregulated power converter is packaged in the first power module, and the first power module is mounted on the first finger-shaped heat sink; The second finger-shaped heat sink, wherein the second unregulated power converter is packaged in the second power module, and the second power module is mounted on the second finger-shaped heat sink; and Multiple liquid pipes are connected between the first finger-shaped radiator and the second finger-shaped radiator, wherein liquid circulates in the first finger-shaped radiator and the second finger-shaped radiator through the multiple liquid pipes.

6. The liquid-cooled power conversion system according to claim 1, comprising: A finger-shaped heat sink, wherein the plurality of first power switches and the plurality of second power switches are mounted on the finger-shaped heat sink; and Multiple liquid conduits are connected to the finger-shaped radiator, wherein liquid circulates within the finger-shaped radiator through the multiple liquid conduits.

7. The liquid-cooled power conversion system according to claim 1, comprising: Finger-shaped radiator, wherein: The first unregulated power converter is packaged in the first power module; The second unregulated power converter is packaged in the second power module; and The first power module and the second power module are mounted on the finger-shaped heat sink; and Multiple liquid conduits are connected to the finger-shaped radiator, wherein liquid circulates within the finger-shaped radiator through the multiple liquid conduits.

8. The liquid-cooled power conversion system according to claim 1, wherein the first unregulated power converter is a first inductor-inductor-capacitor (LLC) resonant converter configured to operate with a fixed duty cycle, wherein, The first LLC resonant converter includes multiple first primary switches, a first resonant tank circuit, a first transformer, and multiple first primary switches; and The second unregulated power converter is a second LLC resonant converter configured to operate with the fixed duty cycle, wherein the second LLC resonant converter includes a plurality of second primary switches, a second resonant tank circuit, a second transformer, and a plurality of secondary stage switches.

9. The liquid-cooled power conversion system according to claim 8, comprising: The first heat sink, wherein the plurality of first primary switches, the first resonant tank circuit, the first transformer and the plurality of first primary switches are mounted on the first heat sink; The second heat sink, wherein the plurality of second primary switches, the second resonant circuit, the second transformer, and the plurality of secondary secondary switches are mounted on the second heat sink; and Multiple liquid pipes are connected between the first radiator and the second radiator, wherein liquid circulates between the first radiator and the second radiator through the multiple liquid pipes, and wherein: The first liquid pipe of the plurality of liquid pipes is equidistant from two adjacent first primary switches; and The second liquid pipe in the plurality of liquid pipes is equidistant from two adjacent primary switches.

10. The liquid-cooled power conversion system according to claim 8, wherein: A first heat sink, wherein a plurality of first primary switches, a first resonant circuit and a plurality of first secondary switches are mounted on the first heat sink; The second heat sink, wherein a plurality of second primary switches, a second resonant circuit and a plurality of secondary secondary switches are mounted on the second heat sink; Multiple first liquid pipes are connected between a first radiator and a second radiator, wherein liquid circulates through the multiple first liquid pipes in the first radiator and the second radiator; A first transformer radiator, wherein the first transformer is mounted on the first transformer radiator; A second transformer radiator, wherein the second transformer is mounted on the second transformer radiator; and Multiple second liquid pipes are connected between the first transformer radiator and the second transformer radiator, wherein liquid circulates within the first and second transformer radiators through the multiple second liquid pipes, and wherein: The first liquid pipe in a plurality of first liquid pipes is equidistant from two adjacent first primary switches; The second liquid pipe in a plurality of first liquid pipes is equidistant from two adjacent first-stage switches; The left edge of the first liquid pipe in a plurality of second liquid pipes is aligned with the left edge of the first transformer; and The right edge of one of the multiple second liquid pipes is aligned with the right edge of the first transformer.

11. The liquid-cooled power conversion system according to claim 8, comprising: A first heat sink, wherein a plurality of first primary switches, a first resonant circuit and a plurality of first primary switches are mounted on the first heat sink; The second heat sink, wherein a plurality of second primary switches, a second resonant circuit and a plurality of secondary secondary switches are mounted on the second heat sink; Multiple first liquid pipes are connected between a first radiator and a second radiator, wherein liquid circulates through the multiple first liquid pipes in the first radiator and the second radiator; as well as Multiple second liquid pipes are connected to the first transformer and the second transformer, wherein the liquid circulates in the first transformer and the second transformer through the multiple second liquid pipes.

12. The liquid-cooled power conversion system according to claim 8, comprising: A first primary heat sink, wherein a plurality of first primary switches and a first resonant circuit are mounted on the first primary heat sink; A primary heat sink, wherein multiple primary switches are mounted on the primary heat sink; A second primary heat sink, wherein multiple second primary switches and a second resonant circuit are mounted on the second primary heat sink; A secondary heat sink, wherein multiple secondary switches are mounted on the secondary heat sink; Multiple primary liquid pipes are connected between a first primary radiator and a second primary radiator, wherein liquid circulates through the multiple primary liquid pipes in the first primary radiator and the second primary radiator. Multiple secondary liquid pipes are connected between the primary radiator and the secondary radiator, through which liquid circulates between the primary radiator and the secondary radiator. A first transformer radiator, wherein the first transformer is mounted on the first transformer radiator; A second transformer radiator, wherein the second transformer is mounted on the second transformer radiator; as well as Multiple transformer liquid pipes are connected between the first transformer radiator and the second transformer radiator, wherein the liquid circulates in the first transformer radiator and the second transformer radiator through the multiple transformer liquid pipes.

13. The liquid-cooled power conversion system according to claim 8, comprising: A first primary heat sink, wherein a plurality of first primary switches and a first resonant circuit are mounted on the first primary heat sink; A primary heat sink, wherein multiple primary switches are mounted on the primary heat sink; A second primary heat sink, wherein multiple second primary switches and a second resonant circuit are mounted on the second primary heat sink; A secondary heat sink, wherein multiple secondary switches are mounted on the secondary heat sink; Multiple primary liquid pipes are connected between a first primary radiator and a second primary radiator, wherein liquid circulates through the multiple primary liquid pipes in the first primary radiator and the second primary radiator. Multiple secondary liquid pipes are connected between the primary radiator and the secondary radiator, through which liquid circulates between the primary radiator and the secondary radiator. as well as Multiple transformer liquid pipes are connected to a first transformer and a second transformer, wherein the liquid circulates in the first transformer and the second transformer through the multiple transformer liquid pipes.

14. The liquid-cooled power conversion system according to claim 1, further comprising: Multiple unregulated power converters are connected between an input voltage bus and an output voltage bus, wherein each of the multiple unregulated power converters includes multiple power switches, and the power switches of the multiple unregulated power converters are immersed in a liquid in a container, the liquid being configured to cool the power switches of the multiple unregulated power converters to achieve balanced current distribution among the multiple unregulated power converters connected between the input voltage bus and the output voltage bus.

15. A liquid-cooled power conversion method, comprising: A first unregulated power converter is provided, connected between an input voltage bus and an output voltage bus, wherein the first unregulated power converter includes a plurality of first power switches; a second unregulated power converter is provided, connected between an input voltage bus and an output voltage bus, wherein the second unregulated power converter includes a plurality of second power switches; and a liquid is circulated to cool the plurality of first power switches and the plurality of second power switches, thereby achieving balanced current distribution between the first unregulated power converter and the second unregulated power converter.

16. The method of claim 15, further comprising: The first unregulated power converter and the second unregulated power converter are configured to operate with the same fixed duty cycle; Multiple first power switches are mounted on the first heat sink; Multiple second power switches are mounted on the second heat sink; as well as The liquid is circulated between the first and second radiators through multiple liquid pipes connected between the first and second radiators.

17. The method of claim 15, further comprising: The first unregulated power converter and the second unregulated power converter are configured to operate with the same fixed duty cycle; The first unregulated power converter is packaged in the first power module; The first power module is mounted on the first heat sink; The second unregulated power converter is packaged in the second power module; Install the second power module on the second heat sink; The liquid is circulated between the first and second radiators through multiple liquid pipes connected between the first and second radiators.

18. A liquid-cooled power conversion method, comprising: A first unregulated power converter is provided, which is connected between an input voltage bus and an output voltage bus, wherein the first unregulated power converter includes a plurality of first power switches; A second unregulated power converter is provided, which is connected between an input voltage bus and an output voltage bus, wherein the second unregulated power converter includes a plurality of second power switches; The liquid is circulated through multiple first liquid pipes to cool multiple first power switches; The liquid is circulated through multiple second liquid pipes to cool multiple second power switches; The flow rate of the first liquid in multiple first liquid pipes and the flow rate of the second liquid in multiple second liquid pipes are dynamically adjusted to achieve balanced current distribution between the first unregulated power converter and the second unregulated power converter.

19. The method of claim 18, further comprising: The first unregulated power converter and the second unregulated power converter are configured to operate with the same fixed duty cycle; Multiple first power switches are mounted on the first heat sink; Multiple second power switches are mounted on the second heat sink; Detect the first current flowing through the first unregulated power converter and the second current flowing through the second unregulated power converter; In response to the first current value being greater than the second current value, the first liquid flow rate in the multiple first liquid pipes is reduced to increase the on-resistance of the multiple first power switches, and the second liquid flow rate in the multiple second liquid pipes is increased to reduce the on-resistance of the multiple second power switches, thereby achieving a balanced current distribution between the first unregulated power converter and the second unregulated power converter. In response to the second current being greater than the first current, the flow rate of the first liquid in the multiple first liquid pipes is increased to reduce the on-resistance of the multiple first power switches, and the flow rate of the second liquid in the multiple second liquid pipes is decreased to increase the on-resistance of the multiple second power switches, thereby achieving a balanced current distribution between the first unregulated power converter and the second unregulated power converter.

20. The method of claim 18, further comprising: Provided a plurality of unregulated power converters connected between an input voltage bus and an output voltage bus, wherein the plurality of unregulated power converters includes a first unregulated power converter and a second unregulated power converter, and wherein each of the plurality of unregulated power converters includes a plurality of power switches; The plurality of unregulated power converters are configured to operate with the same fixed duty cycle; The power switch of one of the plurality of unregulated power converters is mounted on the corresponding heat sink; Detect the current flowing through the plurality of unregulated power converters; Find the unregulated power converter with the highest current and the unregulated power converter with the lowest current. Balanced current distribution is achieved by reducing the liquid flow rate in multiple liquid pipes connected to the unregulated power converter with the highest current and increasing the liquid flow rate in multiple liquid pipes connected to the unregulated power converter with the lowest current.

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