Battery disconnection unit and drive system
By using a combination of dielectric fluid and ceramic substrate in the cooling device of the battery disconnect unit, the problems of high heat flux density and uneven temperature distribution in the existing technology are solved, and an efficient and low-cost cooling effect is achieved.
Patent Information
- Application Number
- CN202410988216.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2023-07-24
- Filing Date
- 2024-07-23
- Publication Date
- 2025-01-24
AI Technical Summary
Existing battery disconnect units require efficient cooling when using relays and SiC semiconductor circuits to cope with high heat flow density and uneven temperature distribution, resulting in high energy consumption, cost and weight increase in cooling systems.
A cooling device filled with dielectric fluid, which generates high turbulence when boiling, achieves efficient evaporative cooling, and conducts heat transfer through a combination of ceramic substrate and copper layer, reducing reliance on high-efficiency cooling plates.
The efficient cooling of power electronic devices is achieved, the energy consumption and cost of the cooling system are reduced, and the uniformity of temperature distribution is improved.
Smart Images
Figure CN119361554A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a battery disconnect unit having the features of independent claim 1 and to a drive system having the features of independent claim 11 . Background Art
[0002] According to the prior art, a battery disconnect unit (Battery Disconnect Unit-BDU) is used to connect and disconnect the battery of an electric vehicle according to the operating state. Here, three BDU configuration schemes are usually used:
[0003] 1. Fuse devices and relays
[0004] 2. Thermoelectric fuses and relays
[0005] 3. Fuse devices, thermoelectric fuses and relays.
[0006] When a combination of relays and circuits implemented with SiC-based semiconductors is used on AMB components for BDUs, active cooling of these components is required, since these semiconductors reach a higher heat flux and at the same time a higher temperature due to their compact design. The AMB stands for Active Metal Brazing, and the component is a ceramic substrate that is directly connected to the base plate via a welded connection. For example, cooling is achieved using a cooling plate through which a coolant flows. Here, according to the prior art, cooling plates made of aluminum sheets in a brazing process can be used. Depending on the requirements related to the current to be switched and the power loss in the form of heat, these cooling plates can be equipped with additional water sheets (internal inserts) to increase the cooling performance. In this case, the AMB components are welded to the cooling plates to achieve optimal heat transfer from the AMB components to the cooling plates via the water sheets entering the cooling fluid.
[0007] Here, high demands are placed not only on the selection of the internal inserts, but also on the volume flow of the cooling fluid and its maximum permissible temperature. The goal is to cool the semiconductors effectively and to ensure that the temperature distribution of the individual chips relative to one another is as uniform as possible.
[0008] These requirements lead to the use of cooling plates with relatively high pressure losses in such cooling concepts. This, combined with the required high volume flows, leads to additional cooling systems with high pumping power. This not only consumes a lot of energy but also leads to high costs and weight for the vehicle due to its size.
[0009] Chips are usually cast to prevent leakage currents and short circuits in conductor paths that run close to each other and in parallel. Additional components, such as a limiting frame and a casting compound, are required, which results in additional costs. Summary of the invention
[0010] The above-mentioned disadvantages are eliminated by a battery disconnect unit having the features of independent claim 1 and a drive system having the features of independent claim 11. Further features and details of the invention are derived from the dependent claims, the description and the drawings. The features and details described here with respect to the battery disconnect unit according to the invention naturally also apply to the drive system according to the invention and vice versa, so that the disclosure with respect to the various aspects of the invention always refers to each other or can refer to each other.
[0011] A first aspect of the present invention is a battery disconnect unit for disconnecting a battery device from at least one load of a drive system, the battery disconnect unit having a cooling device, the cooling device having a dielectric-tight housing, wherein the housing has a substrate and a cooling plate arranged opposite to the substrate, and wherein the housing forms an internal volume, wherein a portion of the internal volume is filled with a dielectric fluid. In addition, the battery disconnect unit has at least one component of a power electronic device, in particular a plurality of components, wherein at least one component of the power electronic device is arranged on the substrate of the cooling device via at least one ceramic substrate. In this case, at least one component of the power electronic device is covered by the dielectric fluid in the internal volume of the housing of the cooling device.
[0012] At least one component of the power electronic device, such as a SiC chip, is arranged on at least one ceramic substrate. Here, multiple components can also be arranged on the ceramic substrate. It is also conceivable that multiple ceramic substrates are respectively provided with at least one component or multiple components.
[0013] At least one component or a plurality of components of the power electronic device generates a high heat flux or heat in a very small space during operation. This heat is partially distributed by conduction through the ceramic substrate and the baseplate.
[0014] Because at least one component of the power electronic device is covered by a dielectric fluid, heat is therefore output to the dielectric fluid, that is to say, the dielectric fluid can first directly absorb the heat of at least one component. Because the dielectric fluid absorbs heat, its temperature rises until it reaches the boiling point under its corresponding boiling temperature and boiling pressure. Under these conditions, a phase change occurs in the dielectric fluid. Due to the boiling of the dielectric fluid, high turbulence in the boiling bubble region is caused, which can cause a very high heat transfer coefficient. This is also referred to as evaporative cooling and is a very efficient form of heat transfer.
[0015] In addition to the high turbulence during boiling and the high energy transfer due to the phase change, there is another factor for efficient cooling. This is the ability to utilize a significant increase in area from the heat source, i.e. at least one component of the power electronics, to the cooling plate. This increase in area results in a significantly lower heat flux at the cooling plate. Therefore, it is not necessary to use an efficient cooling plate. The cooling plate can be dimensioned with a larger flow cross-sectional area or a lower volume flow can be set, which leads to a reduction in pressure losses. Alternatively, an existing cooling plate can be used by thermally connecting the BDU on the corresponding surface to the existing cooling plate.
[0016] It can be advantageous within the scope of the invention if 1% to 100%, preferably 5% to 70%, more preferably 10% to 50% of the interior volume is filled with the dielectric fluid.
[0017] The inner volume can be completely filled with the dielectric fluid, thereby ensuring that at least one component of the power electronics is covered by the dielectric fluid even when the entire drive system is moving.
[0018] However, it is sufficient to cover at least one component for cooling. Thus, depending on the size of the volume or the size of the substrate, at least 1% of the inner volume can be filled. However, preferably 5% to 70% or 10% to 50% is filled.
[0019] As a result, cooling can be carried out in an optimal manner by evaporative cooling and possible boiling losses can be compensated.
[0020] It is conceivable within the scope of the invention to provide a copper layer, in particular a cold-sprayed copper layer, between the base plate and the ceramic substrate.
[0021] The use of a copper layer to connect the ceramic substrate to the base plate is particularly advantageous, since not only a thermal connection but also a mechanical connection can be achieved quickly and efficiently. In this case, the ceramic substrate together with at least one component is connected to the copper layer on the base plate in a material-locking manner by means of a soldering process. This allows very good heat transfer from the ceramic substrate to the base plate.
[0022] The partial heat dissipation via the copper layer and the base plate can be further increased by producing the base plate from a material that conducts heat well, such as aluminum.
[0023] It can be provided within the scope of the invention that a pressure compensation device is provided in the housing of the cooling device for compensating the pressure in the interior volume.
[0024] This allows the pressure in the inner volume to be balanced when the pressure increases due to the volume increase of the dielectric fluid caused by heating. It can already make sense to use a pressure compensation device, such as a film pressure compensation container, when at least 70% of the inner volume, but at any rate 100% is filled with dielectric fluid.
[0025] It is also conceivable that, if up to a maximum of 99.9% of the interior volume is filled with the dielectric liquid, the remainder of the interior volume is filled with an auxiliary medium, in particular a compressible medium.
[0026] By using an auxiliary medium, pressure compensation can be achieved in the event of a volume change of the dielectric fluid.
[0027] In particular, compressible media such as air, nitrogen and inert gases have proven to be particularly advantageous as auxiliary media.
[0028] It is also conceivable that the cooling plate of the cooling device has at least two, preferably a plurality of cooling fins on an inner surface facing the inner volume and / or on an outer surface facing away from the inner volume.
[0029] By means of cooling fins on the inner surface facing the inner volume or on the outer surface facing away from the inner volume, an additional surface area increase can be achieved, by which heat can be dissipated. At the same time, it is conceivable to additionally cool the cooling plate by means of an outer surface having at least two cooling fins in order to cool the dielectric, so that as much heat as possible can be dissipated from the components of the power electronics.
[0030] Within the scope of the invention, the outer side of the cooling plate of the cooling device can optionally be connected to a cooling unit of the load or of the battery device, or a liquid cooling device or an air cooling device can be provided.
[0031] By connecting to an external cooling unit or a liquid cooler, the cooling plate can be additionally cooled efficiently, so that rising, boiling dielectric fluid can be cooled quickly in order to be used again as condensate for cooling the at least one component.
[0032] Furthermore, it can be provided within the scope of the invention that the dielectric fluid has a viscosity of 0.5 mPas to 1000 mPas, preferably 0.5 mPas to 500 mPas, more preferably 0.5 mPas to 100 mPas.
[0033] Dielectric fluid is a non-conductive fluid. Dielectric fluid can also have the viscosity of the increase in the scope between 1mPas to 1000mPas. In this case, viscosity can change temporarily due to the dielectric fluid heating. Simultaneously, it should be ensured that there is a certain viscosity, so that uniform flow can be produced. At this, dielectric fluid preferably has a viscosity of 50-700mPas, because they can ensure to flow evenly and absorb heat flux well.
[0034] It is conceivable in connection with the present invention that the dielectric fluid has a heat capacity of 0.8 to 4 kJ / kgK, preferably 1.0 to 2.5 kJ / kgK, more preferably 2 to 3 kJ / kgK.
[0035] Dielectric fluids with increased heat capacity are able to absorb and dissipate more heat. Thus, dielectric fluids with a heat capacity of 0.8 to 4 kJ / kgK ensure that the generated heat is dissipated quickly and efficiently.
[0036] Furthermore, it is conceivable to provide a battery interface for electrical connection to a battery device and a load interface for electrical connection to a load.
[0037] The battery interface and the load interface are particularly advantageous for a simple connection to a battery unit or a load of the drive system. In this case, these load interfaces or battery interfaces can be provided for controlling and regulating the battery disconnect unit or the battery unit and the load via the battery disconnect unit. However, data-communicating load interfaces or battery interfaces are also conceivable, which transmit specific data, such as the temperature or pressure in the internal volume, to the control unit.
[0038] A second aspect of the present invention is a drive system according to the present invention, which has a battery device, a load and a battery disconnect unit according to the first aspect, wherein the battery device and the battery disconnect unit are electrically connected to each other via a battery interface, and wherein the load and the battery disconnect unit are connected to each other via a load interface.
[0039] The drive system includes the battery disconnect unit described above and its advantages.
[0040] The advantages which have been described in detail with respect to the battery disconnect unit according to the first aspect of the invention also apply to the drive system according to the second aspect of the invention. BRIEF DESCRIPTION OF THE DRAWINGS
[0041] Further advantages, features and details of the invention are apparent from the following description, in which a number of exemplary embodiments of the invention are described in detail with reference to the accompanying drawings. The features mentioned in the claims and the description can form the subject matter of the invention individually or in any combination. The invention is illustrated in the following figures:
[0042] Figure 1 is a schematic diagram of a battery disconnect unit according to the present invention,
[0043] Figure 2 is a schematic diagram of a drive system according to the present invention. DETAILED DESCRIPTION
[0044] Figure 11 shows a battery disconnect unit 10 for disconnecting a battery device 12 from at least one load 14 of a drive system 16. The battery disconnect unit 10 has a cooling device 18, which has a medium-tight housing 20 and at least one component 28, in particular a plurality of components 28, of a power electronic device 30. Here, the housing 20 of the cooling device 18 has a base plate 22 and a cooling plate 24 arranged opposite to the base plate 22, and forms an inner volume 26, wherein a part of the inner volume is filled with a dielectric fluid 52. At least one component 28 of the power electronic device 30 is arranged on the base plate 22 of the cooling device 18 through or by means of at least one ceramic substrate 32. At this time, in order to increase the surface area for heat dissipation, at least one component 28 of the power electronic device 30 is covered by the dielectric fluid 52 in the inner volume 26 of the housing 20 of the cooling device 18.
[0045] In the illustrated embodiment, approximately 70% of the interior volume 26 is filled with the dielectric fluid 52. However, it is contemplated that between 1% and 100% of the interior volume 26 may be filled with the dielectric fluid 52.
[0046] In the operation of the battery disconnect unit 10, the components 28 of the power electronic device 30 will heat up and generate higher heat flux or heat. This heat is exported to the dielectric fluid 52, and the dielectric fluid begins to boil and undergoes phase change. Thus, the boiling bubbles 56 formed here rise and are cooled when arriving at the cooling plate 24 and fall into the dielectric fluid 52 as condensate 58 again. This has produced the turbulence required for optimal heat transfer. At the same time, the condensate 58, i.e. the condensed dielectric fluid 52 has exported heat energy to the cooling plate 24, thereby cooling at least one component 28 again.
[0047] In order to connect the ceramic substrate 32 to at least one component 28 of the power electronic device 30 , a copper layer 34 , in particular a cold-sprayed copper layer 34 , is provided between the base plate 22 and the ceramic substrate 32 . This enables a reliable thermal and mechanical connection to the base plate 22 .
[0048] In order to increase the reliability in the event of a pressure increase due to the volume increase of the dielectric fluid, a pressure compensation device 36 in the form of a film pressure compensation vessel is provided in the inner volume 26 of the housing 20 of the cooling device 18 .
[0049] Since the inner volume 26 is not completely filled, but only about 70%, the rest of the inner volume 26 is filled with an auxiliary medium 54. For this purpose, a compressible medium is preferably used. In this case, the auxiliary medium 54 is air.
[0050] In order to cool the cooling plate 24, that is, to be able to provide the dew point of the dielectric fluid as quickly as possible, cooling fins 42 can be provided. Figure 1In the embodiment of the embodiment of the present invention, a plurality of cooling fins 42 are arranged at the outer surface 40 facing away from the inner volume 26. In addition or alternatively, at least two cooling fins 42 can also be arranged on the inner surface 38 facing the inner volume 26.
[0051] To cool the cooling plate 24 from the outside, it is provided with a liquid cooling device 46. In a further embodiment not shown here, the cooling plate 24 of the battery disconnect unit 10 can be connected to an external cooling unit 44, so that an already provided cooling unit 44 of the load 14 or the battery device 12 can be used.
[0052] The dielectric fluid 52 used here has a viscosity of 0.5 mPas 20° C. to 1000 mPas 20° C. and a heat capacity of 0.8 to 4 kJ / kgK.
[0053] In addition, according to Figure 1 In the embodiment of FIG. 1 , a battery interface 48 for electrically connecting to the battery device 12 and a load interface 50 for electrically connecting to the load 14 are provided.
[0054] Figure 2 It is shown in Figure 1 The drive system 16 with a battery device 12, a load 14 and a battery disconnect unit 10. Here, the battery device 12 and the battery disconnect unit 10 are electrically connected to each other via a battery interface 48. At the same time, the load 14 and the battery disconnect unit 10 are connected to each other via a load interface 50.
Claims
1. A battery disconnect unit (10) for disconnecting a battery device (12) from at least one load (14) of a drive system (16), the battery disconnect unit comprising: A cooling device (18) comprising a dielectric-tight housing (20), wherein the housing (20) comprises a base plate (22) and a cooling plate (24) arranged opposite the base plate (22), and wherein the housing (20) forms an inner volume (26), wherein a portion of the inner volume (26) is filled with a dielectric fluid (52); at least one component (28), in particular a plurality of components (28), of a power electronic device (30), At least one component (28) of the power electronic device (30) is arranged on a base plate (22) of the cooling device (18) via at least one ceramic substrate (32), wherein at least one component (28) of the power electronic device (30) is covered by a dielectric fluid (52) in an inner volume (26) of a housing (20) of the cooling device (18).
2. The battery disconnect unit (10) according to claim 1, It is characterized in that 1% to 100%, preferably 5% to 70%, more preferably 10% to 50% of the inner volume (26) is filled with a dielectric fluid (52).
3. The battery disconnect unit (10) according to claim 1 or 2, It is characterized in that A copper layer (34), in particular a cold-sprayed copper layer (34), is arranged between the base plate (22) and the ceramic substrate (32).
4. A battery disconnect unit (10) according to any one of the preceding claims, It is characterized in that A pressure compensation device (36) is arranged in the housing (20) of the cooling device (18), and is used to balance the pressure in the inner volume (26).
5. A battery disconnect unit (10) according to any one of the preceding claims, It is characterized in that When the inner volume (26) is filled to a maximum of 99.9% with the dielectric fluid, the remainder of the inner volume (26) is filled with an auxiliary medium (54), in particular a compressible medium.
6. A battery disconnect unit (10) according to any one of the preceding claims, It is characterized in that The cooling plate (24) of the cooling device (18) has at least two, preferably a plurality of cooling fins (42) on an inner surface (38) facing the inner volume (26) and / or an outer surface (40) facing away from the inner volume (26).
7. A battery disconnect unit (10) according to any one of the preceding claims, It is characterized in that The outer side of the cooling plate (24) of the cooling device (18) can be connected to a cooling unit (44) of a load (14) or a cooling unit (44) of a battery device (12), or provided with a liquid cooling device (46) or an air cooling device (46).
8. A battery disconnect unit (10) according to any one of the preceding claims, It is characterized in that The viscosity of the dielectric fluid (52) is 0.5 mPas (20°C) to 1000 mPas (20°C), preferably 0.5 mPas (20°C) to 500 mPas (20°C), more preferably 0.5 mPas (20°C) to 100 mPas (20°C).
9. A battery disconnect unit (10) according to any one of the preceding claims, It is characterized in that The heat capacity of the dielectric fluid (52) is 0.8 to 4 kJ / kgK, preferably 1.0 to 2.5 kJ / kgK, more preferably 2 to 3 kJ / kgK.
10. The battery disconnect unit (10) according to any one of the preceding claims, It is characterized in that The battery interface (48) is provided for electrical connection to the battery device (12), and the load interface (50) is provided for electrical connection to the load (14).
11. A drive system (16), comprising a battery device (12), a load (14) and a battery disconnect unit (10) according to any of the preceding claims, wherein the battery device (12) and the battery disconnect unit (10) are electrically connected to each other via a battery interface (48), and wherein the load (14) and the battery disconnect unit (10) are connected to each other via a load interface (50).