Electronic power module

Abstract

Electronic power module, comprising a housing (2) with a carrier circuit board (4) which is arranged therein and on which a plurality of electronic power components (20) are arranged in a first group and a plurality of capacitors (21) are arranged in a second group and at least two connections (22) are provided adjacent to each other, and comprising a cooling plate (8) which, by way of a first side (9), is arranged in thermal contact with the carrier circuit board (4), wherein the cooling plate (8) has, on a second side (10) situated opposite the first side (9), channel projections (11) which bear against the housing (2) and via which a cooling channel (12) is defined between the cooling plate (8) and the housing (2), a coolant (26) supplied via a channel inlet (18) and discharged via a channel outlet (19) being guidable through the cooling channel, wherein the channel (12) has a first channel section (23) which extends adjacent to the first group comprising the power components (20) and which has a first channel cross-sectional area, this first channel section (23) having an adjoining meanderingly guided second channel section (24) which extends adjacent to the second group comprising the capacitors (21) and adjacent to the connections (22) and has a second channel cross-sectional area which is smaller than the first channel cross-sectional area.

Description

[0001] Electronic power module

[0002] The invention relates to an electronic power module.

[0003] Such an electronic power module is used, for example, in a motor vehicle in conjunction with an electric drive system and includes an appropriately dimensioned energy storage device. It comprises various electronic components, at least some of which are arranged on a carrier board. These components are power components, usually in the form of MOSFETs, i.e. high-performance transistors, capacitors and at least two connections, preferably an alternating voltage connection and a direct voltage connection, i.e. an AC and a DC connection. During operation, heat is generated primarily by the power components, which is dissipated to the outside as waste heat. The power components are components with a relatively low heat capacity, i.e. they are heat-sensitive components within the module.Overheating of these power components should therefore be avoided wherever possible, as overheating can lead to a loss of power and even malfunctions. Efficient heat dissipation and thus cooling of these power components is therefore necessary. The capacitors also heat up during operation and therefore also contribute to the total heat loss. However, capacitors are less heat-sensitive than power components, i.e. they have a greater heat capacity. Their heat management is less critical than that of the power components. Cooling of the capacitors is necessary, but the cooling requirements are not as great as for cooling power components. Finally, heat losses can also occur at the connections, where the heat loss generated is comparable to that at the capacitors, which is why the cooling requirements are also comparable to that of the capacitors.

[0004] The invention is based on the problem of providing an electronic power module with improved cooling of the relevant components. To solve this problem, the invention provides an electronic power module comprising a housing with a carrier board arranged therein, on which a plurality of electronic power components are arranged in a first group and a plurality of capacitors in a second group, as well as at least two terminals adjacent to one another, and a cooling plate arranged with a first side in thermal contact with the carrier board. The cooling plate has channel projections abutting the housing on a second side opposite the first side, via which channel projections a cooling channel is defined between the cooling plate and the housing, through which a coolant can be guided, supplied via a channel inlet and discharged via a channel outlet. The channel has a first channel section.which extends adjacent to the first group comprising the power components and which has a first channel cross-sectional area, to which first channel section is connected a meandering second channel section which extends adjacent to the second group comprising the capacitors and adjacent to the terminals, and which has a second channel cross-sectional area which is smaller than the first channel cross-sectional area.

[0005] The power module according to the invention is characterized firstly in that the electronic power components, for example the MOSFETs, as well as the capacitors, are each arranged in groups. The power components are arranged in a first circuit board area as a first group, and the capacitors are arranged in a second circuit board area in a second group. This means that corresponding regions are defined in which components are concentrated, each exhibiting identical thermal behavior and therefore requiring equal cooling, although the two regions require different cooling. Likewise, the connections are arranged adjacent to one another, i.e., they are also provided locally concentrated on the carrier board. The carrier board is arranged in a housing that encloses the module to the outside.

[0006] According to the invention, the power module further comprises a cooling plate, which is also arranged in the housing. This cooling plate is preferably flat on one side and rests with this side in thermal contact with the carrier board, with contact over the largest possible area being preferred, since the size of the contact surface ultimately determines the heat transfer rate from the heating components via the carrier board to the cooling plate. On the second side, opposite this first side resting against the carrier board, the cooling plate has channel projections which, in the assembled position, rest against the inside or inner surface of the housing, so that a cooling channel is defined between the cooling plate and the housing via the structuring of the cooling plate with the channel projections and the cooling plate surface. A channel inlet and a channel outlet are also provided.A fluid coolant, e.g. water or oil, to be carried through the channel can be introduced into the channel via the channel inlet, and after flowing through the entire channel it is discharged via the channel outlet. According to the invention, the channel is structured in a specific way along its length. It has two communicating channel sections, a first channel section and an adjoining second channel section. The first channel section extends adjacent to the first group comprising the power components. This means that, with reference to the arrangement of the power components on the side of the carrier board facing away from the channel, it runs congruently or overlaps the arrangement area of ​​the power components. This first channel section has a first channel cross-sectional area that is relatively large.The aim is to ensure that the flow velocity in this channel section is not too high, so that the fluid coolant flows sufficiently slowly through the first channel section and a correspondingly longer residence time in this area is provided in order to achieve a high heat transfer rate in this first channel section. This means that the flow velocity and the pressure drop in the first channel section are low, resulting in a longer residence time and a high heat transfer rate. In contrast, the second channel section adjoining the first channel section has a meandering shape and extends adjacent to the second group comprising the condensers and adjacent to the connections. This means that this second channel section, with its meandering shape, is positioned congruent with the arrangement area of ​​the condensers and the two connections.The second channel section has a second channel cross-sectional area that is smaller than the first channel cross-sectional area. This change in cross-section results in a higher flow velocity and a greater pressure drop in this second channel cross-section. This means that the coolant flows faster through the second channel section, meaning the residence time is shorter. However, this is sufficient, as only the heat from the less temperature-sensitive condensers and connections needs to be dissipated via this second channel section. Although the heat transfer rate is ultimately lower than the heat transfer rate in the first channel section, the lower heat transfer rate in the second channel section is still sufficient to absorb and dissipate the heat loss at the condensers and connections and to adequately cool these components.

[0007] The power module according to the invention is characterized, on the one hand, by the grouped arrangement of the power components and capacitors and the closely spaced arrangement of the terminals, as well as by a specific channel design, divided into a first, large-diameter channel section and a second, smaller-diameter, meander-shaped channel section. This design allows for efficient, specific cooling in specific areas within a compact structure.

[0008] In a further development of the invention, the cooling plate can have a plurality of projections projecting from the side on the second side, wherein the projections project into the first channel section and / or the second channel section. These projections serve to enlarge the heat transfer surface within the channel, as they project from the second side of the cooling plate, for example a metal plate, and into the channel. The coolant flowing through them flows around them. Depending on the number of projections projecting into the first and / or second channel section, the heat transfer surface in the respective channel section can be considerably increased.

[0009] A first group of projections can protrude into the first channel section and be distributed substantially over the entire channel section. The projections consequently enlarge the heat transfer surface in the first channel section, wherein, as stated, a large amount of heat must be dissipated in this region since, as stated, the power components which heat up more quickly are cooled via this channel section. By having as many projections as possible and packing them as densely as possible, a significant increase in the heat transfer surface is ensured, so that a high heat transfer rate can be achieved. The projections also contribute to evening out the flow of the coolant in the first channel section, wherein their integration means there is no significant pressure drop within the first channel section since the entire channel cross-section is designed accordingly.

[0010] Furthermore, a second group of projections can extend into the second channel section only in the area of ​​the connections. As described, the two connections are arranged in close proximity to each other. Accordingly, the projections of the second group are concentrated in this area. Slightly more heat will be lost at the connections during operation than at the condensers, so increasing the heat transfer surface in the area of ​​the connections is advantageous.

[0011] The projections are preferably pin-shaped, meaning they are not particularly large in cross-section, but can be distributed in large numbers. The projections preferably have a cylindrical cross-section, which is advantageous for good flow around the element with low flow resistance.

[0012] As explained, the projections provided on the cooling plate extend into the cooling channel. To avoid a type of bypass occurring in this area due to an excessive distance between the ends of the projections and the housing wall, in which the coolant flows preferentially due to less resistance, it is expedient according to an advantageous development of the invention if housing projections are provided on the side facing the cooling plate, which extend to the projections provided on the cooling plate. This means that, almost mirror-inverted to the arrangement of the projections on the cooling plate, corresponding housing projections are provided on the housing inner wall, which extend to the projections on the cooling plate side, so that any existing distance is reduced and any bypass in this area can be avoided.It is particularly useful if the projections provided on the cooling plate and the housing projections touch each other, creating a virtually continuous projection. The number of housing projections preferably corresponds to the number of projections on the cooling plate.

[0013] Alternatively, it is also conceivable for the projections provided on the cooling plate to be in direct contact with the housing. In this case, any bypass is also avoided, while the inner surface of the housing remains flat.

[0014] The invention is explained below using exemplary embodiments with reference to the drawings. The drawings are schematic representations and show:

[0015] Figure 1 is a perspective schematic diagram of an electronic power module according to the invention,

[0016] Figure 2 is a sectional view through the power module of Figure 1 along the line ll-ll in Figure 1,

[0017] Figure 3 shows a further schematic diagram to explain the arrangement of the two channel sections and the projections relative to the first group comprising the power components, the second group comprising the capacitors and the terminals,

[0018] Figure 4 is a schematic diagram, based on the diagram in Figure 3, to explain the fluid flow, and

[0019] Figure 5 is a schematic diagram of the liquid volume present in the cooling channel in its position relative to the first group comprising the power components, the second group comprising the capacitors and the arrangement of the connections.

[0020] Figure 1 shows an electronic power module 1 according to the invention, the interior of which can be seen in the sectional view according to Figure 2. The power module 1 comprises a housing 2, for example made of plastic. Arranged inside the housing 2 is a power board 3 comprising a carrier board 4 and a plurality of electronic components 5 arranged thereon, wherein the components 5 are arranged on a first side 6 of the carrier board 4. A metal cooling plate 8 sits on the second, flat side 7 of the carrier board 4. The metal cooling plate 8 has a flat first side 9 which sits flat on the second side 7 of the carrier board 4 via a thermal paste (not shown in detail). Very good heat transfer from the carrier board 4 to the cooling plate 8 is achieved via the thermal paste and the large-area contact zone.

[0021] The cooling plate 8 has channel projections 11 on a second side 10, which define a cooling channel 12, which, as will be discussed below, consists of two adjacent channel sections with different flow cross-sections and channel cross-sections, respectively. In the example shown, the outer, circumferential channel projections 11 are provided with grooves 13, which serve to accommodate a sealing agent such as a paste or a sealing element such as a rubber seal, in order to achieve a seal with the inner surface of the housing 2.

[0022] Furthermore, a plurality of individual projections 14 are provided, which protrude from the second side 10 of the cooling plate 8 into the channel 12. The distribution of the projections 14 within the channel 12 varies, which will be discussed below. A plurality of housing projections 16 are also provided on the inner side 15 of the housing 2, which project in the direction of the projections 14 of the cooling plate 8 and preferably abut against them, resulting in virtually continuous overall projections. The number of housing projections 16 preferably corresponds to the number of projections 14. The projections 14 and the housing projections 16 are preferably pin-like and cylindrical in cross-section.

[0023] Furthermore, Figure 2 also shows that housing channel projections 17 are provided on the inner side 15, which project toward the channel projections 11 of the cooling plate 8 and preferably also abut against them to delimit the respective channel sections. If corresponding housing projections 16 and channel projections 17 are provided, their arrangement and their course are congruent with the arrangement and course of the projections 16 and the channel projections 11.

[0024] As Figure 1 shows, a channel inlet 18 and a channel outlet 19 are provided on the housing side, via which a fluid coolant can be introduced into the channel 12, which flows completely through it and is then discharged again.

[0025] Figure 3 shows a schematic diagram of the arrangement of the components 5 arranged on the carrier board 4 and of the course of the cooling channel 12 relative to the components 5. The components 5 comprise first components in the form of electronic power components 20, which are arranged in a first group in relatively dense packaging on the carrier board 4. The components 5 also comprise second components in the form of capacitors 21, which are arranged in a second group, likewise in relatively dense packaging on the carrier board 4. Furthermore, two connections 22 are provided, which can be, for example, AC and DC connections. These are also formed closely adjacent to one another on the carrier board 4.

[0026] Also shown is the cooling channel 12, with the channel sections 11 bordering the cooling channel 12 and defining it towards the housing 2 being shown by way of example. The channel 12 comprises a first channel section 23 into which the coolant supplied via the channel inlet 18 initially flows. This first channel section 23 has a relatively large cross-section, i.e. the first channel cross-sectional area of ​​this first channel section 23 is relatively large. The first channel section 23 merges into a meandering second channel section 24 at the transition 25. The meandering second channel section 24 has a significantly smaller channel cross-sectional area than the first channel section, as shown in Figure 3. The coolant flowing through the second channel section 24 is then discharged to the outside via the channel outlet 19.

[0027] The first channel section 23 is clearly assigned to the first group comprising the power components 20, i.e., it extends directly adjacent to them. The channel section 23 thus runs virtually congruently with the arrangement area of ​​the power components 20. The second channel section 24, on the other hand, runs adjacent to the arrangement of the second group comprising the capacitors 21 and the terminals 22, as clearly shown in Figure 3. The second channel section 24 thus also runs virtually congruently with the arrangement area of ​​the capacitors 21 and the terminals 22.

[0028] As a result of the different channel cross-sectional area, the coolant flows through the first channel section 23 at a relatively low flow velocity and a correspondingly longer residence time, with a low pressure drop across the length of the first channel section 23. In contrast, the significant reduction in cross-section in the second channel section 24 results in a higher flow velocity, combined with a higher pressure drop across the channel length. As a result of the longer residence time, a large amount of heat can be absorbed in the first channel section 23, which is necessary because the power components 20 heat up considerably during operation and are considerably temperature-sensitive compared to the capacitors 21, which also need to be cooled, but not as large an amount of heat needs to be dissipated as in the area of ​​the power components 20.These different cooling requirements are taken into account by the channel geometry according to the invention.

[0029] Figure 3 further shows the arrangement of the projections 14 in their distribution in the channel sections 23, 24. It can be seen that a large number of individual, pin-like, and cylindrical projections 14 are provided in the first channel section 23. This means that almost the entire channel surface is covered with corresponding projections 14, resulting in a correspondingly high density of projections 14. Figure 3 further shows that only a few projections 14 are provided in the second channel section 24, specifically in the area of ​​the contacts 22, which require somewhat greater cooling than the capacitors 21. As described, the respective projections 14 achieve a considerable local enlargement of the heat transfer surface in the respective area, so that the heat transfer rate can be significantly increased locally.

[0030] Figure 4 shows the flow path of the coolant, for which corresponding flow arrows are shown. The coolant 26 clearly flows in at the channel inlet 18 and is then distributed over the entire channel cross-section of the first channel section 23. The flow velocity decreases as it flows into the channel section 23; it is relatively low, resulting in a correspondingly long residence time of the coolant in the cooling section 23. The coolant 46 then flows into the second channel section 24 and, in Figure 4, initially to the left, where it then flows 180° to the right and then flows to the channel outlet 19. The flow velocity in the second channel section 24 is significantly higher, resulting from the significantly smaller channel cross-section. The flow velocity is therefore adapted to the cooling requirements of the components 5 assigned to the respective channel sections 23, 24.

[0031] Finally, Figure 5 shows a schematic diagram of the power board 3 comprising the carrier board 4 and the components 5 arranged thereon, as well as the associated liquid volume 27, i.e., the coolant 26, as it is accommodated in the channel 12 as well as in the inlet 18 and outlet 19. In this illustration, the liquid volume 27 is shown as a negative representation of the cavity or volume of the channel inlet 18, the channel 12, and the channel outlet 19.Also shown is Zone I, the area in which the power components 20 are arranged on the carrier board 4 and in which there is a high density of projections 14 (which appear as depressions in the negative liquid volume 27), and Zone II, the area in which the capacitors 21 and the connections 22 are arranged on the carrier board 4 and in which the projections 14 are only provided in the area of ​​the connections 22 (which also appear as depressions in the negative liquid volume 27). It is clear that the liquid volume 27 completely covers Zone I, so that there is large-area heat transfer and a high heat transfer rate, just as Zone II is completely covered by the liquid volume 27, and there too there is a correspondingly large-area heat transfer and a lower, but sufficient, heat transfer rate in this area. List of reference symbols.

[0032] Power module

[0033] Housing

[0034] Power board

[0035] Carrier board

[0036] Component first side second side

[0037] Cooling plate first side second side

[0038] Channel projection

[0039] cooling channel

[0040] Nut

[0041] projection

[0042] inside

[0043] Housing projection

[0044] Housing channel projection

[0045] Sewer inlet

[0046] Sewer outlet

[0047] Power component

[0048] capacitor

[0049] Connection first channel section second channel section

[0050] transition

[0051] coolant

[0052] Liquid volume

[0053] Zone

[0054] Zone

Claims

Patent claims 1. An electronic power module comprising a housing (2) with a carrier board (4) arranged therein, on which a plurality of electronic power components (20) are arranged in a first group and a plurality of capacitors (21) in a second group, and at least two terminals (22) are provided adjacent to one another, and a cooling plate (8) arranged with a first side (9) in thermal contact with the carrier board (4), wherein the cooling plate (8) has channel projections (11) resting against the housing (2) on a second side (10) opposite the first side (9), via which channel projections a cooling channel (12) is defined between the cooling plate (8) and the housing (2), through which a coolant (26) supplied via a channel inlet (18) and discharged via a channel outlet (19) can be guided, wherein the channel (12) has a first channel section (23),which extends adjacent to the first group comprising the power components (20) and which has a first channel cross-sectional area, to which first channel section (23) a meandering second channel section (24) adjoins, which extends adjacent to the second group comprising the capacitors (21) and adjacent to the terminals (22), and which has a second channel cross-sectional area which is smaller than the first channel cross-sectional area.

2. Electronic power module according to claim 1, characterized in that the cooling plate (8) has on the second side (10) a plurality of projections (14) projecting from the side, wherein the projections (17) project into the first channel section (23) and / or the second channel section (24).

3. Electronic power module according to claim 2, characterized in that a first group of projections (14) projects into the first channel section (23), distributed substantially over the channel (12).

4. Electronic power module according to claim 2 or 3, and in that a second group of projections (14) projects into the second channel section (24) only in the region of the terminals (22).

5. Electronic power module according to one of claims 2 to 4, characterized in that the projections (14) are pin-like.

6. Electronic power module according to claim 5, characterized in that the projections (14) have a cylindrical cross-section.

7. Electronic power module according to one of claims 2 to 6, characterized in that housing projections (17) are provided on the housing (2) on the side (15) facing the cooling plate (8), which projections extend to the projections (14) provided on the cooling plate (8).

8. Electronic power module according to claim 7, characterized in that the projections (14) of the cooling plate (8) and the housing projections (17) of the housing touch each other.

9. Electronic power module according to one of claims 2 to 6, characterized in that the projections (14) provided on the cooling plate (8) bear against the housing (2).

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