Power conversion assembly and vehicle

Abstract

The embodiment of the invention provides a power conversion assembly and a vehicle. The power conversion assembly includes: a circuit board; at least one power switching device arranged on the circuit board; a heat sink disposed near the circuit board and configured to dissipate heat of the at least one power switching device; and at least one coupling portion located between the at least one power switching device and the heat sink and thermally coupled to the at least one power switching device and the heat sink, the at least one coupling portion being made of a thermally conductive and electrically insulating material comprising hexagonal boron nitride nanosheets. According to the scheme, heat dissipation and insulation of the power conversion assembly can be effectively improved, and cost and process complexity related to heat dissipation are reduced.

Description

Technical Field

[0001] The present disclosure relates to the technical field of heat dissipation and insulation of electrical equipment, and more particularly, to a power conversion assembly, an on-board charger, an on-board DC-DC converter, and a vehicle. Background Art

[0002] To reduce greenhouse gases and mitigate climate change, new energy vehicles, such as electric vehicles, are rapidly developing and becoming increasingly popular. In these vehicles, both charging energy storage devices and powering consumer devices requires onboard power converters. These converters utilize a large number of medium-voltage and high-voltage power devices to achieve power conversions such as AC to DC, DC to AC, and DC to DC. The high voltages, high currents, and high-frequency switching during the power conversion process cause these power devices to generate significant heat.

[0003] As power electronics devices and products in vehicles become increasingly miniaturized and feature more functionality, heating issues with power devices and their associated integrated circuits are severely hindering technological development. Consequently, there is a need to improve and enhance the heat dissipation capabilities of power devices. Furthermore, since power devices in vehicles operate in high-voltage, live environments, improving heat dissipation also requires ensuring insulation isolation of the live components within the system. Summary of the Invention

[0004] To at least partially address the above-mentioned and other possible problems, embodiments of the present disclosure provide a power conversion assembly, an on-board charger, an on-board DC-DC converter, and a vehicle.

[0005] According to a first aspect of the present disclosure, a power conversion assembly is provided, comprising: a circuit board; at least one power switching device arranged on the circuit board; a heat sink arranged near the circuit board and configured to dissipate heat for the at least one power switching device; and at least one coupling portion located between the at least one power switching device and the heat sink and thermally coupled to the at least one power switching device and the heat sink, the at least one coupling portion being made of a thermally conductive and electrically insulating material, the material comprising hexagonal boron nitride nanosheets.

[0006] According to a second aspect of the present disclosure, there is provided an on-vehicle charger comprising the power conversion assembly according to the first aspect.

[0007] According to a third aspect of the present disclosure, a vehicle-mounted DC-DC conversion device is provided, comprising the power conversion assembly according to the first aspect.

[0008] According to a fourth aspect of the present disclosure, a vehicle is provided, comprising at least one of the following: the on-board charger according to the second aspect; and the on-board DC-DC converter according to the third aspect.

[0009] This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the disclosure, nor is it intended to limit the scope of the disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The above and other objects, features and advantages of the present disclosure will become more apparent through a more detailed description of exemplary embodiments of the present disclosure with reference to the accompanying drawings, wherein like reference numerals generally represent like components throughout the exemplary embodiments of the present disclosure.

[0011] Figure 1 A schematic diagram of the power components is shown.

[0012] Figure 2 A schematic diagram of a power conversion assembly according to an embodiment of the present disclosure is shown.

[0013] Figure 3 A schematic diagram of a vehicle according to an embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0014] Embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to make the present disclosure more thorough and complete, and to fully convey the scope of the present disclosure to those skilled in the art. Those skilled in the art can derive alternative technical solutions from the following description without departing from the spirit and scope of protection of the present disclosure.

[0015] As used herein, the term "including" and its variations mean open inclusion, i.e., "including but not limited to." Unless otherwise stated, the term "or" means "and / or." The term "based on" means "based, at least in part, on." The term "one embodiment" means "at least one example embodiment." Other explicit and implicit definitions may be included below.

[0016] Embodiments of the present disclosure provide an improved heat dissipation solution for power conversion. This improved solution utilizes a novel coupling portion, made of a material including hexagonal boron nitride nanosheets, to thermally couple the power switching device and the heat sink. This coupling portion significantly improves thermal conductivity between the power switching device and the heat sink, while also further enhancing insulation between the two. Furthermore, this improved solution can reduce the overall cost and manufacturing process of the power conversion assembly.

[0017] Figure 1 Schematic diagram of power component 100' is shown. Figure 1As shown, the power assembly 100' includes a power component 101' and a heat sink 102'. The power component 101' can be a power switching device, or a combination of a power switching device and other components (such as a printed circuit board PCB and related components), and the heat sink 102' is used to dissipate heat from the power component 101'.

[0018] Power component 100' also includes a heat sink paste (HSP) layer 103'. HSP layer 103' serves as a dielectric layer to provide electrical insulation between power component 101' and heat sink 102'. HSP layer 103' primarily comprises epoxy resin or other polymer materials with excellent electrical insulation properties and high mechanical strength. However, because polymer materials themselves have a low thermal conductivity (approximately 0.1 to 0.5 W / (m·K)), to improve the thermal conductivity of HSP layer 103' and maintain or enhance its electrical insulation properties, high thermal conductivity fillers, such as aluminum oxide (Al2O3), aluminum nitride (AlN), and hexagonal boron nitride (h-BN), are further added to the polymer matrix of epoxy resin or other polymer materials to improve its thermal conductivity and maintain or enhance its electrical insulation properties. HSP with high thermal conductivity fillers has a thermal conductivity of approximately 1.3 W / (m·K), and its breakdown voltage, which represents its insulation properties, can reach over 27 kV / mm. In addition, the power component 100' further includes a thermal interface material (TIM) layer 104'. The TIM layer 104' is made of a material with good thermal conductivity and can effectively bond the HSP layer 103' to the heat sink 102' to improve thermal contact and heat conduction between the HSP layer 103' and the heat sink 102'.

[0019] exist Figure 1In the illustrated power assembly 100', the dual-layer structure consisting of an HSP layer 103' and a TIM layer 104' achieves electrical insulation and thermal conductivity between the high-voltage power components and the heat sink, thereby providing a thermal management design for the power components. However, this design has serious drawbacks. Specifically, with technological advancements, product functionality has increased and size has continued to decrease. To ensure the performance of power electronic devices, it is necessary to more effectively transfer and dissipate the heat generated by high-power components to avoid the adverse effects of high temperatures on system performance. However, the thermal conductivity of HSP is only approximately 1.3 W / (m·K), making the HSP layer a bottleneck and limitation in the thermal path for transferring heat from the high-power components to the heat sink. Furthermore, the use of HSP increases the cost and process complexity of the power assembly's printed circuit board (PCB). Because HSP needs to be applied to the PCB, the PCB's through-holes must be pre-filled with a filler such as epoxy resin to prevent the HSP from flowing into the PCB's through-holes and onto the back of the PCB. In some automotive power conversion devices, the bare PCB cost accounts for approximately 55% of the total PCB cost, while the HSP and filler cost accounts for approximately 20%. Clearly, the use of HSP increases the overall system cost.

[0020] The embodiments of the present disclosure can eliminate the limitation of HSP on the heat dissipation of power components and significantly improve the thermal conductivity and electrical insulation performance. In addition, the embodiments of the present disclosure can also effectively reduce the manufacturing cost of the system and simplify the manufacturing process. Figure 2 and Figure 3 to describe the embodiments of the present disclosure.

[0021] Figure 2 FIG1 shows a schematic diagram of a power conversion component 100 according to an embodiment of the present disclosure. As an example, the power conversion component 100 may be a component capable of implementing power conversion operations, such as a rectifier component, a DC-DC conversion component, an inverter component for charging and power supply in a vehicle, or other components and circuits that require the use of power switches. Figure 2As shown, the power conversion assembly 100 includes a circuit board 110 and power switching devices 120-1 and 120-2, and the power switching devices 120-1 and 120-2 are arranged on the circuit board 110. Specifically, by controlling the connection and disconnection of the power switching devices 120-1 and 120-2, the power conversion assembly 100 can effectively implement power conversion operations to obtain power with a desired voltage and / or current. As an example, the circuit board 110 can be a printed circuit board PCB, and the power switching devices and other components can be arranged and connected thereon. In one embodiment, the power switching devices 120-1 and 120-2 include metal oxide semiconductor field effect transistors MOSFET. MOSFET has many advantages such as fast switching speed, high reliability, and easy integration, and is suitable for power conversion operations at higher voltage levels. However, it is understandable that the power switching device can also be other types of semiconductor switching devices.

[0022] Although Figure 2 Two power switching devices 120-1 and 120-2 are shown in the figure, but more or fewer power switching devices may be provided as needed, for example, one, four, or six power switching devices. The embodiments of the present disclosure do not impose any restrictions on the number of power switching devices. In addition, it is understood that the power conversion assembly 100 also includes other circuits, elements, or components (such as inductors, capacitors, etc.) for implementing power conversion operations, and for the purpose of simplicity, they are not shown in the figure.

[0023] According to an embodiment of the present disclosure, the power conversion assembly 100 includes a heat sink 130, which is arranged near the circuit board 110 and is configured to dissipate heat for the power switching devices 120-1 and 120-2. Specifically, due to high-frequency switching and high voltage levels, the power switching devices 120-1 and 120-2 will generate severe heat, resulting in an increase in temperature. High temperature will degrade the performance of the power conversion assembly 100 and its components, and even cause damage to the components. The heat sink 130 can receive heat from the power switching devices 120-1 and 120-2 and conduct and dissipate it to the external environment. As an example, the heat sink 130 can be made of a material with high thermal conductivity (such as copper, aluminum, or other metals), and in one example, the heat sink 130 can also include a cooling pipe and a refrigerant flowing therein to conduct heat to the external environment more quickly. However, the embodiments of the present disclosure do not impose any restrictions on the material of the heat sink 130 or whether it includes cooling pipes and refrigerant, as long as the heat sink is suitable for being arranged near the circuit board and can cool or dissipate heat from the heat-generating power switching device.

[0024] According to an embodiment of the present disclosure, power conversion assembly 100 further includes coupling portions 140-1 and 140-2, which are located between power switching devices 120-1 and 120-2 and heat sink 130 and are thermally coupled to power switching devices 120-1 and 120-2 and heat sink 130. Coupling portions 140-1 and 140-2 are made of a thermally conductive and electrically insulating material, which includes hexagonal boron nitride nanosheets.

[0025] Specifically, power switching devices 120-1 and 120-2 are electrically charged and carry a relatively high voltage, and heat sink 130 is typically not an insulator. Therefore, coupling portions 140-1 and 140-2 can provide insulation isolation between power switching devices 120-1 and 120-2 and heat sink 130. Furthermore, coupling portions 140-1 and 140-2 should not inhibit heat transfer between power switching devices 120-1 and 120-2 and heat sink 130. As discussed above, the dual-layer construction of HSP and TIM can provide insulation and thermal conductivity to a certain extent. However, the thermal conductivity of HSP with thermally conductive fillers is still relatively low, at only 1.3 W / (m·K). Some studies have found that graphene has better performance than bulk graphite and is an ideal thermally conductive filler. Unfortunately, however, graphene does not meet the required insulation properties. Therefore, the mediocre thermal conductivity and high cost of HSP limit further improvements in heat dissipation capabilities. Research has shown that hexagonal boron nitride nanosheets (BNNS), also known as "white graphene," are a material with excellent insulating and thermal conductivity properties. Its theoretical thermal conductivity is as high as 1700-2000 W / (m·K), and its breakdown voltage is approximately 35 kV / mm, both far exceeding the thermal conductivity and breakdown voltage of HSP. The use of BNNS in coupling portions 140-1, 140-2 can effectively improve heat transfer between power switching devices 120-1, 120-2 and heat sink 130 and enhance the insulation between them, making the power conversion assembly suitable for applications with higher power consumption and smaller space requirements. Due to the extremely high thermal conductivity and breakdown voltage of BNNS, coupling portions 140-1, 140-2 can be made thinner and eliminate the need for additional components such as TIM layers, reducing overall costs and simplifying the manufacturing process. In one embodiment, BNNS can be obtained by peeling from an h-BN bulk. Thus, a BNNS for the coupling portions 140 - 1 , 140 - 2 can be obtained in a simple and low-cost manner.

[0026] It is understood that although the figure shows two coupling portions, more or fewer coupling portions may be provided depending on the number of power switching devices and other high-power consumption components that require heat dissipation. Furthermore, in the case of multiple coupling portions, some or all of the multiple coupling portions may be connected together to form an integral body, rather than being separated from each other.

[0027] In some embodiments of the present disclosure, power switching devices 120-1 and 120-2 are arranged on a first side of circuit board 110, and heat sink 130 and coupling portions 140-1 and 140-2 are arranged on a second side of circuit board 110, opposite the first side. Power conversion assembly 100 also includes metal members 150-1 and 150-2, which are arranged to pass through circuit board 110 and are thermally coupled to power switching devices 120-1 and 120-2 on the first side of circuit board 110, and are thermally coupled to heat sink 130 via coupling portions 140-1 and 140-2 on the second side of circuit board 110. By way of example, the metal members may be made of copper or other metals with good thermal conductivity. Metal members 150-1 and 150-2 may be embedded within circuit board 110 and are capable of transferring heat from power switching devices 120-1 and 120-2 located on one side of circuit board 110 to coupling portions 140-1 and 140-2 and heat sink 130 located on the other side of circuit board 110. For example, metal member 150-1 may be thermally coupled to power switching device 120-1 at one end and to coupling portion 140-1 at the other end, and thermally coupled to heat sink 130 via coupling portion 140-1; and metal member 150-2 may be thermally coupled to power switching device 120-2 at one end and to coupling portion 140-2 at the other end, and thermally coupled to heat sink 130 via coupling portion 140-2. In other words, each metal member may couple a corresponding power switching device to the coupling portion and the heat sink. However, one metal piece may also thermally couple two or more power switching devices to the coupling portion and the heat sink, or one power switching device may be thermally coupled to the coupling portion and the heat sink via two or more metal pieces, and the embodiments of the present disclosure do not impose any limitation on this.

[0028] In an alternative embodiment, the power switches 120-1 and 120-2 can be thermally coupled directly to the heat sink 130 via the coupling portions 140-1 and 140-2, without the need for the metal members 150-1 and 150-2. For example, the heat sink 130 and the power switches 120-2 and 120-2 can be arranged on the same side of the circuit board 110. However, placing the heat sink 130 and the power switches 120-2 and 120-2 on different sides of the circuit board 110 and providing the metal members 150-1 and 150-2 is more preferred because this allows for more flexible arrangement of the heat sink 130 and components on the circuit board 110, resulting in a more rational overall layout and better facilitating heat dissipation from the heat sink 130 to the external environment.

[0029] In some embodiments of the present disclosure, each coupling portion 140-1, 140-2 includes a single-layer film formed of BNNS, which contacts the corresponding metal part 150-1, 150-2 on one side and contacts the heat sink 130 on the other side. Specifically, because BNNS has a very high breakdown voltage and thermal conductivity, only a single-layer film made of BNNS is required to achieve the required insulation and thermal conductivity without the need for an interface layer such as a TIM layer, which reduces the manufacturing cost of the power conversion component and simplifies the manufacturing process. In one embodiment, the thickness of the single-layer film formed of BNNS is between 0.02 mm and 0.2 mm. Thus, only a BNNS film with a very small thickness and low cost is required to provide enhanced insulation and thermal conductivity. In one embodiment, the coupling portions 140-1, 140-2 can be formed by adhering a single-layer film of BNNS to the surface of the circuit board 110. Specifically, in a dual-layer HSP and TIM construction, HSP coating is required, and a filler must be placed in the through-holes of circuit board 110 before coating. Furthermore, an interface layer must be placed after HSP coating and curing. In contrast, the BNNS film requires only a simple process to attach to circuit board 110, significantly simplifying the manufacturing process of power conversion assembly 100.

[0030] Figure 3 FIG1 shows a schematic diagram of a vehicle 1000 according to an embodiment of the present disclosure. As an example, the vehicle 1000 may be an electric vehicle or a hybrid vehicle, or may be any other type of vehicle that needs to be charged or powered and needs to perform power conversion during the charging or powering process. Figure 3As shown, vehicle 1000 includes at least one of an onboard charger 1001 and an onboard DC-DC converter 1002. The power conversion assembly 100 according to an embodiment of the present disclosure can be the onboard charger 1001 or a portion of the onboard charger 1001, or can be the onboard DC-DC converter 1002 or a portion of the onboard DC-DC converter 1002. The onboard charger 1001 is used to power the energy storage device 1003 of the vehicle 1000. For example, the onboard charger 1001 can convert the voltage and current of an external AC power source and DC power source into the voltage and current required by the energy storage device 1003. In addition, the onboard DC-DC converter 1002 is used to power the vehicle's electrical devices, providing the appropriate DC voltage and DC current to the vehicle's electrical devices. In one embodiment, the onboard charger 1001 and the onboard DC-DC converter 1002 can be combined to form an onboard charging and distribution unit CHARCON. In the CHARCON, the onboard charger 1001 and onboard DC-DC converter 1002 are housed in the same housing, significantly reducing its size. This significantly increases heat dissipation requirements. By utilizing the power conversion assembly 100 according to embodiments of the present disclosure, heat dissipation and insulation are addressed for the onboard charger 1001, the onboard DC-DC converter 1002, and the CHARCON. This effectively conducts and dissipates heat generated by the power switching devices, thereby improving the operation of high-power devices within the vehicle and, consequently, enhancing the overall vehicle performance.

[0031] Through the teachings given in the above description and the associated drawings, many modifications and other embodiments of the present disclosure given here will be recognized by those skilled in the art of the present disclosure. Therefore, it is to be understood that the embodiments of the present disclosure are not limited to the specific embodiments disclosed, and modifications and other embodiments are intended to be included within the scope of the present disclosure. In addition, although the above description and the associated drawings have described the example embodiments in the context of certain example combinations of parts and / or functions, it should be appreciated that different combinations of parts and / or functions can be provided by alternative embodiments without departing from the scope of the present disclosure. In this regard, for example, other combinations of parts and / or functions that are different from those explicitly described above are also expected to be within the scope of the present disclosure. Although specific terms are used here, they are used only in a general and descriptive sense and are not intended to be limiting.

Claims

1. A power conversion assembly (100), comprising: a circuit board (110); At least one power switching device (120-1, 120-2) is arranged on the circuit board (110); a heat sink (130) arranged near the circuit board (110) and configured to dissipate heat for the at least one power switching device (120-1, 120-2); as well as At least one coupling portion (140-1, 140-2) is located between the at least one power switching device (120-1, 120-2) and the heat sink (130), and is thermally coupled to the at least one power switching device (120-1, 120-2) and the heat sink (130). The at least one coupling portion (140-1, 140-2) is made of a thermally conductive and electrically insulating material, and the material includes hexagonal boron nitride nanosheets.

2. The power conversion assembly (100) according to claim 1, wherein the at least one power switching device (120-1, 120-2) is arranged on a first side of the circuit board (110), and the heat sink (130) and the at least one coupling portion (140-1, 140-2) are arranged on a second side of the circuit board (110) opposite to the first side, and The power conversion assembly (100) further includes: At least one metal piece (150-1, 150-2) is arranged to pass through the circuit board (110) and is thermally coupled to the at least one power switching device (120-1, 120-2) on the first side, and is thermally coupled to the heat sink (130) via the at least one coupling portion (140-1, 140-2) on the second side.

3. The power conversion assembly (100) according to claim 2, wherein each of the at least one coupling portion (140-1, 140-2) comprises a single-layer film formed of the hexagonal boron nitride nanosheets, the single-layer film contacting the corresponding metal member (150-1, 150-2) on one side thereof and contacting the heat sink (130) on the other side thereof.

4. The power conversion assembly (100) according to claim 3, wherein the thickness of the single-layer film is between 0.02 mm and 0.2 mm.

5. The power conversion assembly (100) according to claim 3, wherein the at least one coupling portion (140-1, 140-2) is formed by attaching the single-layer film to a surface of the circuit board (110).

6. The power conversion assembly (100) according to claim 1, wherein the hexagonal boron nitride nanosheets are obtained by performing exfoliation from a hexagonal boron nitride bulk.

7. The power conversion assembly (100) of claim 1, wherein the at least one power switching device (120-1, 120-2) comprises a metal oxide semiconductor field effect transistor.

8. An on-vehicle charger (1001), comprising a power conversion assembly (100) according to any one of claims 1 to 7.

9. An on-vehicle DC-DC conversion device (1002), comprising a power conversion assembly (100) according to any one of claims 1 to 7.

10. A vehicle (1000) comprising at least one of the following: The on-board charger (1001) according to claim 8; and The vehicle-mounted DC-DC converter (1002) according to claim 9.

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