Power electronics cooler, power electronics device and inverter

Abstract

Power electronics cooler (KL) for cooling a power electronics device (LV), comprising: - a base plate (BP) and a top plate (DP) which together enclose a cooling channel (KN) for conveying a coolant, which extends in a longitudinal direction (LR) of the cooler (KL); - a coolant inlet (EL) and a coolant outlet (AL) which are arranged in the longitudinal direction (LR) at a first longitudinal end (E1) of the cooling channel (KN); - an insert plate (EP) which is arranged in the cooling channel (KN) between the base plate (BP) and the top plate (DP) and which divides the cooling channel (KN) into a supply flow channel section (ZF) extending from the coolant inlet (EL) to a second longitudinal end (E2) of the cooling channel (KN) opposite the first longitudinal end (E1) and a return flow channel section (RF) extending from the second longitudinal end (E2) to the coolant outlet (AL);- wherein the insert plate (EP) encloses the supply flow channel section (ZF) with the base plate (BP) and the return flow channel section (RF) with the top plate (DP); - wherein the insert plate (EP) has a through-opening (DO) at its second longitudinal end (E2) for allowing the coolant to pass from the supply flow channel section (ZF) to the return flow channel section (RF); - wherein the insert plate (EP) further has at least one through-opening (BO, TO) for allowing a portion of the coolant to pass directly from the supply flow channel section (ZF) to the return flow channel section (RF);- wherein the insert plate (EP) has a temperature-controlled valve (VT) at the at least one through-hole (BO, TO) which is configured to block or release the coolant flow through the at least one through-hole (BO, TO) depending on coolant temperatures in the supply flow channel section (ZF) and / or in the return flow channel section (RF), - wherein the at least one through-hole (BO, TO) includes a dead water opening (TO) for allowing a portion of the coolant to pass from the supply flow channel section (ZF) directly to a dead water area (TG) of the return flow channel section (RF).

Description

Technical field: The present invention relates to a power electronics cooler or a cooler for cooling a power electronics device, e.g., a DC-DC converter or an inverter, in particular an electric drive of a motor vehicle. The invention further relates to a power electronics device with said cooler and an inverter with said power electronics device. State of the art and object of the invention: Power electronics coolers for cooling a power electronics device are known and are used, among other things, in (power) DC-DC converters or (power) inverters, e.g., of electrically powered vehicles, for cooling the power electronics devices or power modules (with several power semiconductor switches or comparable circuit components with high power losses) of the DC-DC converters or inverters. For example, in so-called EPF2.3 inverters (a product of Vitesco Technologies GmbH), coolers are used to cool a power electronics device of the inverter or its power modules (with several power semiconductor switches). The German patent application DE 11 2018 007 544 T5 describes a cooler for cooling a semiconductor device with a base plate and a jacket as well as a separating element arranged between these two parts with several inlet openings through which a coolant can flow from a cooling channel inlet-side cooling channel section to a cooling channel outlet-side cooling channel section. German patent application DE 11 2015 005 715 T5 describes a cooler for cooling a power electronics module, comprising a cooling channel with several inlet connecting tubes for distributing the coolant into multiple subchannels of the cooling channel. The cooler also features several valves located at the inlet points of the connecting tubes, which regulate the coolant flow into the respective inlet connecting tubes. Due to the circuit design of the power device and its power modules, such coolers require homogeneous cooling of the power device and its modules (and all power semiconductor switches or comparable circuit components with high power losses). This is intended to prevent local high temperature spikes on the power device and its modules, which could otherwise lead to a drop in performance, malfunctions, or even failure of the power device or inverter, or at least a reduction in service life. The purpose of the present application is therefore to provide a means by which a power electronics device, e.g. an inverter or a DC-DC converter, or its power modules (with several power semiconductor switches or comparable circuit components with high power losses) can be cooled homogeneously. Description of the invention: This problem is solved by the subject matter of the independent claims. Advantageous embodiments are the subject matter of the dependent claims. According to a first aspect of the invention, a power electronics cooler or a cooler for cooling a power electronics device, e.g. a DCDC converter or an inverter, in particular of an electrically powered vehicle, is provided. The radiator has a base plate and a top plate which together (at least partially) enclose a cooling channel that extends in a longitudinal direction of the radiator and serves to allow the flow of a coolant, such as cooling water. The cooler also has a coolant inlet and a coolant outlet, which are arranged at a first longitudinal end of the cooling channel when viewed in the longitudinal direction (in particular next to each other and thus one behind the other when viewed in a transverse direction of the cooler). The cooler also features an insert plate located in the cooling channel between the base plate and the top plate. This insert plate divides the cooling channel into (at least) a supply flow channel section extending from the coolant inlet to a second longitudinal end of the cooling channel opposite the first, and (at least) a return flow channel section extending from the second longitudinal end of the cooling channel to the coolant outlet. The insert plate, together with the base plate, encloses the supply flow channel section (at least partially, or up to openings to be described later), and the top plate encloses the return flow channel section (at least partially, or up to openings to be described later). The insert plate has at least one through-opening (or through-recess, i.e., a lateral cutout in the insert plate) at its second longitudinal end, which is designed to allow the coolant to flow from the supply flow channel section to the return flow channel section. The supply flow channel section and the return flow channel section are fluidically connected in series via this through-opening. Furthermore, the insert plate has (at least) one passage opening between the coolant inlet and the through-hole, and thus between the first and second longitudinal ends of the cooling channel, to allow a portion of the coolant to pass directly from the supply flow channel section – i.e., without flowing through the through-hole – to the return flow channel section. Furthermore, the insert plate has a temperature-controlled valve at the at least one through-hole, which is designed to control and / or regulate the coolant flow through the at least one through-hole depending on coolant temperatures in the supply flow channel section and / or in the return flow channel section, i.e., to (completely) block or (partially or completely) release the flow through the at least one through-hole. The at least one passage opening has a dead water opening, which is designed to allow part of the coolant to pass from the supply flow channel section directly to a possible dead water area of ​​the return flow channel section. The top plate, insert plate, and base plate can each be a largely plate-shaped cooling component with correspondingly shaped side sections, which together form a fluid-tight enclosure of the cooling channel (except for the coolant inlet and outlet). The insert plate can be separated from the base plate and top plate without damage, or removed from the cooling channel, and can also be mechanically connected to them. Viewed perpendicular to the insert plate or the cooler (and thus in a direction perpendicular to the plane in which the longitudinal and transverse directions of the cooler run), the top plate, the return flow channel section, the insert plate, the supply flow channel section, and the bottom plate are stacked one above the other in that order. The supply flow channel section and the return flow channel section are fluidically connected in series and together form a U-shaped cooling channel (i.e., in the form of ⊃ or ⊂) that is tilted laterally in the transverse direction of the cooler. During operation, the coolant flows in each of the two channel sections in one of two opposing directions (a supply flow and a return flow). The cover plate can serve, in particular, for the (direct) thermal contacting of the power electronics device. In other words, circuit components of the power electronics device with high power dissipation or high heat generation, such as power semiconductor switches, can be (directly) mounted on the cover plate or thermally contacted with it. The cover plate can thus act as a heat exchanger from the aforementioned circuit components of the power electronics device to the coolant flowing through the cooling channel. Specifically, the cover plate can be designed as a circuit carrier, such as a ceramic substrate, for the power electronics device or its power modules, on which the aforementioned circuit components are mounted and electrically connected. The actual heat absorption from the cover plate, and thus the cooling of the circuit components of the power electronics device arranged on the cover plate and thermally connected to it (with high power loss or high waste heat, such as power semiconductor switches), is primarily carried out by the feedback flow channel section or the coolant flowing through the feedback flow channel section.The primary purpose of the supply flow channel section is to guide the coolant from the coolant inlet to the second longitudinal end of the cooling channel, which is furthest from the coolant inlet. This allows the coolant to flow through the through-opening at the second longitudinal end from the supply flow channel section to the return flow channel section. From the second longitudinal end, it can flow (back) along the entire length of the cooler, and thus along the entire length of the cover plate, to the coolant outlet at the first longitudinal end of the cooler, thereby absorbing the waste heat from the cover plate and cooling the circuit components of the power electronics device. The cover plate can be made of a known (especially thermally conductive) cooling material, such as aluminum or an aluminum alloy, in order to better absorb the waste heat from the circuit components of the power electronics device arranged on the cover plate and transfer it to the coolant flowing around the cover plate. The insert plate and the base plate can be made of the same material as the top plate or of another known, lightweight and inexpensive (especially with good thermal conductivity) material, such as a plastic. The coolant inlet and coolant outlet can be formed as parts of the base plate on the base plate. During cooling operation of the cooler, at least one through-hole directs a portion of the coolant from the supply flow channel section directly to the return flow channel section, allowing this portion of the coolant to bypass or not flow through sections of the supply flow channel section and the return flow channel section. This allows the portion of the coolant that is still cool to bypass sections of the supply and return flow channels and mix with the remaining coolant, which flows from the supply channel through the through-holes to the return channel and is relatively warm, in the middle of the return channel section. This results in a largely uniform temperature in the coolant within the return channel section and reduces the overall pressure drop in the cooling channel. Furthermore, the portion of the coolant that flows directly into the return flow channel section through the at least one through-hole can generate additional (laminar) flows in the channel area of ​​the return flow channel section around the at least one through-hole, thereby preventing the coolant from accumulating or circulating in this channel area and thus forming a so-called dead water area. In particular, the at least one through-hole interrupts an asymmetrical flow of the coolant in the return flow channel section, thus ensuring largely homogeneous cooling of the cover plate without a temperature hotspot in the return flow channel section or on the cover plate. The temperature-controlled valve allows the entire coolant flow through the return flow channel section to be influenced and controlled during the entire cooling operation of the cooler with regard to pressure drop, flow velocity, and flow direction within the return flow channel section. The temperature-controlled valve continuously and automatically changes the coolant flow through the at least one orifice during the entire cooling operation of the cooler, without any active external intervention, depending on the coolant temperatures in the supply flow channel section and / or the return flow channel section. This ensures that, through targeted dynamic mixing of the coolant, an average coolant temperature is achieved and maintained across the entire return flow channel section during the entire cooling operation. A dead zone is a section of the return flow channel where the coolant would accumulate or not flow from the through-hole to the coolant outlet in the main flow direction within a predetermined time if the insert plate did not have at least one through-hole as described above. Accordingly, the description always refers to a "potential" dead zone. The dead zone is also, in particular, a turbulent flow area in the return flow channel section, similar to a separation bubble, which would be separated from, or have a weak flow through, or be reached by the (usually laminar) main coolant flow if the insert plate did not have at least one through-hole as described above.During the development of the invention and through multiple tests under various and as realistic as possible environmental and operating conditions with a comparable cooler without the aforementioned at least one through-hole in the insert plate, it was found that the dead water zone forms particularly around a corner or on a side section of the return flow channel. A dead water zone can also be defined as an area in the return flow channel section where the coolant recirculates or stagnates and thus cannot flow through or out. The dead water zone in the return flow channel section is determined, for example, in a flow simulation with a cooler with an insert plate without the aforementioned at least one through-hole. In particular,An area in the return flow channel section is designated as a dead water area if the coolant in the return flow channel section does not flow from the through-opening to the coolant outlet in its main flow direction within a predetermined time period, but instead circulates in the said area or is stationary or stalled in its flow movement. The at least one through-hole, allowing a portion of the coolant to pass from the supply flow channel section directly to the potential dead water area of ​​the return flow channel section, enables the coolant flowing into or through the supply flow channel section (and thus still cold) to directly bypass this area. Because this area is cooled by the freshly flowing, and therefore comparatively cold, coolant entering the cooling channel, it is cooled earlier than the rest of the cover plate. The at least one through-hole can be positioned and dimensioned in the insert plate depending on the identified potential dead water area, ensuring that the potential dead water area in the return flow channel section is surrounded as completely as possible by a sufficient quantity of coolant. This coolant flows directly from the supply flow channel section through the at least one through-hole into the potential dead water area. This results in a comparatively homogeneous flow around the entire return flow channel section, which in turn allows for comparatively homogeneous cooling of the cover plate without a temperature hotspot on the cover plate caused by a dead water area. The dead water area in the recirculation channel section can be determined in a flow simulation, such as a CFD simulation (CFD: in English "Computational Fluid Dynamics", in German "Numerische Strömungsmechanik"), with a comparable cooler with an insert plate without the aforementioned at least one through-hole. The minimum one through-hole can then be positioned and dimensioned (shape and dimensions, such as diameter) in the insert plate depending on the identified potential dead water area. Furthermore, multiple through-holes can be installed, with their number, position, and dimensions (shape and dimensions or diameter) being determined, among other things, by the location and size of the potential dead water area (expected without the through-hole). This provides a way to homogeneously cool a power electronics device, e.g. an inverter or a DC-DC converter, or its power modules (with several power semiconductor switches or comparable circuit components with high power losses). Several passage openings can be provided, distributed in the longitudinal and transverse direction of the cooling channel and thus located at different positions on the insert plate. The at least one passage opening can have a bypass opening, which is designed to allow a portion of the coolant to pass directly from the supply flow channel section to the return flow channel section without passing through the passage opening. The bypass opening serves to divert a portion of the coolant directly from the supply channel section to the return channel section, bypassing the entire flow path from the supply channel section through the through-holes to the return channel section. This allows the cooler portion of the coolant to bypass sections of both the supply and return channels and mix with the remaining, relatively warm coolant flowing through the entire path from the supply channel section through the through-holes to the return channel section. This results in a largely uniform coolant temperature within the return channel section and reduces the overall pressure drop in the cooling channel.For this purpose, several bypass openings can be provided, which are evenly distributed over the entire surface of the insert plate in order to achieve the most homogeneous mixing of the coolant in the return flow channel section. In the case of multiple passage openings, some of them can act as bypass openings and the rest as dead water openings. The valve can be designed as a diaphragm valve. The valve can also be designed as a bimetallic valve. In addition, the valve can be configured to block or release the coolant flow through at least one passage opening, depending on the temperature difference between the temperatures of the coolant in the supply flow channel section and in the return flow channel section. The valve can also be configured, depending on local coolant temperatures in the supply flow channel section and / or in the return flow channel section, to block or release the coolant flow through the at least one passage opening and / or the temperature difference between these local coolant temperatures. Here, the local coolant temperatures are the coolant temperatures in channel areas of the supply flow channel section or the return flow channel section around the at least one through-hole. The valve can further be configured, depending on the (local) coolant temperatures in the supply flow channel section and in the return flow channel section, to not allow, partially allow, or completely allow the coolant flow through the at least one passage opening and / or the temperature difference between these (local) coolant temperatures, and thus to control or regulate the coolant flow through the at least one passage opening or the flow rate of the part of the coolant flowing through the at least one passage opening. The insert plate can have a return opening (or a return recess, i.e., another lateral cutout in the insert plate) at or near the first longitudinal end of the cooling channel and (immediately) upstream of the coolant outlet. This opening serves to guide the coolant from the return flow channel section to the coolant outlet and is fluidically separated, and in particular sealed, from the supply flow channel section by a sealing wall that (at least partially) surrounds the return opening. The return opening provides a direct fluid connection between the return flow channel section and the coolant outlet. The sealing wall fluidly separates the return flow channel section and the coolant outlet from the supply flow channel section and the coolant inlet, creating a fluid-tight seal, thus preventing direct flow of coolant from the coolant inlet or outlet.is effectively prevented from flowing directly from the feed flow channel section into the return flow channel section or the coolant outlet. The term "fluidically connected" means that a direct flow of coolant from a first cooling channel section to another cooling channel section that is "fluidically connected" to this first channel section is continuously possible. Similarly, the term "fluidically separated" means that a direct flow of coolant from the first cooling channel section to a third cooling channel section that is "fluidically separated" from this first channel section is permanently prevented. The sealing wall can be formed on the insert plate and / or the base plate and extend from the insert plate towards the base plate or from the base plate towards the insert plate. The sealing wall can extend from the insert plate towards the base plate as a further projection (or as an additional fixed component of the insert plate). Alternatively or additionally, the sealing wall can also extend from the base plate towards the insert plate as a projection (or as a fixed component of the base plate). The top plate and / or the insert plate may have a surface-enhancing structure, such as cooler pin fins, that protrudes into the return flow channel section. The cooler may have a flow guide structure and / or a flow guide wall in the supply flow channel section, designed to direct the coolant from the coolant inlet or the flow channel area to the through-opening. The flow guide structure or the flow guide wall may extend in the longitudinal direction of the cooling channel. The flow-guiding structure or flow-guiding wall can project from the insert plate (or as an additional fixed component of the insert plate) into the feed flow channel section. Alternatively or additionally, the flow-guiding structure or flow-guiding wall can also project from the base plate (or as an additional fixed component of the base plate) into the feed flow channel section. The cooler or base plate can have a ramp-like, inclined, moving elevation at the coolant inlet, designed to direct the coolant from the coolant inlet towards the flow opening. According to a second aspect of the invention, a power electronics device is provided which, for example, forms part of a DCDC converter or an inverter. The device comprises at least one power module and a previously described cooler, wherein the power module is arranged on a surface of the cover plate facing away from the return flow channel section and is thermally contacted or connected to the cover plate. The top plate can be a circuit carrier, such as a DCB substrate or an AMB substrate, or a part thereof. The power module can include power semiconductors, which may be configured as SiC semiconductor switches or IGBT semiconductor switches. According to a third aspect of the invention, an inverter is provided which includes a power electronics device as described above and a control circuit (or a driver circuit) for controlling (or operating) the power electronics device or the power module. The control circuit is electrically (or via signal connections) connected to the power module of the power electronics device or to the power semiconductors of the power module via control signal connections. Brief description of the drawings: An exemplary embodiment of the invention is explained in more detail below with reference to the accompanying drawings. Figure 1 shows a schematic cross-sectional view of parts of an inverter with a cooler according to an exemplary embodiment of the invention; and Figure 2 shows a schematic top view of parts of the cooler from Figure 1. Detailed description of the drawings: Fig. 1 and Fig. 2 each show, in a schematic cross-sectional and top view respectively, parts of an inverter with a cooler according to an exemplary embodiment of the invention, which serves, for example, as a power inverter of an electric drive system of a motor vehicle for providing phase currents for a drive electric motor of the drive system. The inverter has a power device LV with a cooler KL for cooling the power device LV, on which the power device LV is arranged and is also mechanically and thermally connected to it. The power device LV has a circuit carrier, for example made of an aluminum alloy or a thermally conductive ceramic, which also forms a cover plate DP of the cooler KL. On a surface OF of the circuit carrier or cover plate DP facing away from the cooler KL, the power device LV has three (in particular, identically shaped) power modules LM, which are arranged one behind the other in a longitudinal direction of the cover plate DP, which is also the longitudinal direction LR of the cooler KL. The three power modules LM are evenly distributed on the surface OF of the cover plate DP at equal intervals, so that each is located on one of three approximately equal-sized areas (in Fig. 1 a left, a middle, and a right area) of the surface OF, each of which occupies approximately one-third of the total area of ​​the surface OF. Each of the three power modules LM in turn has four power semiconductor switches LH1 and LH2, respectively, arranged in pairs in two rows next to each other, so that each of the two pairs of power semiconductor switches LH1 and LH2 of each power module LM, viewed in the longitudinal direction LR around the longitudinal axis LA of the cover plate DP, is arranged on the right and left sides of the longitudinal axis LA of the cover plate DP, respectively, as is more clearly shown in Fig. 2. The four power semiconductor switches LH1 and LH2 of the respective power modules LM each form two positive-voltage-side and two negative-voltage-side power semiconductor switches of two parallel-connected half-bridges of a bridge circuit of the inverter. In this embodiment, all power semiconductor switches LH1 and LH2 are, for example, SiC semiconductor switches. Furthermore, the four power semiconductor switches LH1 and LH2 of the respective power modules LM are arranged in pairs, distributed across two sub-areas located to the left and right of the longitudinal axis LA of the cover plate DP and situated on one of the three aforementioned surface areas (in Fig. 1, the left, middle, and right surface areas) of the surface OF. For the sake of simplicity, a sub-area of ​​the right surface area of ​​the surface OF, located to the right in Fig. 1 and thus directly to the left of an inlet EL of the cooler (see also Fig. 2), will be designated as the first area B1, and the remaining five sub-areas of the left, middle, and right surface areas will be collectively designated as the second area B2. This will allow for a clearer and more straightforward illustration of the characteristics of the first area B1 compared to the second area B2 and the technical function of the cooler KL. The two power semiconductor switches of the power module LM on the left in Fig. 1, which are located in the first area B1, are hereinafter referred to as reference numeral LH1, while the two remaining power semiconductor switches of the same power module LM and the power semiconductor switches of the two remaining power modules LM are hereinafter referred to as reference numeral LH2. The inverter further comprises a control circuit including driver circuits (not shown in the figure) for controlling the power electronics device LV or operating the aforementioned power semiconductor switches LH1, LH2, which is / are electrically connected via control signal connections (not shown in the figure) to the power semiconductor switches LH1, LH2 of the power electronics device LV or to their control terminals. In addition to the aforementioned top plate DP, the cooler KL also has a bottom plate BP, which, together with the top plate DP, encloses a cooling channel KN for conveying a liquid coolant, such as cooling water, which extends in the longitudinal direction LR of the cooler KL. The cooler KL further has a coolant inlet EL and a coolant outlet AL (see Fig. 2 ) which are formed on the base plate BP and are arranged next to each other in the longitudinal direction LR and thus one behind the other in a transverse direction QR of the cooler KL at a first longitudinal end E1 of the base plate BP or of the cooling channel KN (see Fig. 2 ). The cooler KL also features an insert plate EP, which is arranged in the cooling channel KN between the base plate BP and the cover plate DP. This insert plate divides the cooling channel KN into a supply flow channel section ZF, extending from the coolant inlet EL (i.e., from the first longitudinal end E1 of the cooling channel KN) in the longitudinal direction LR to a second longitudinal end E2 (opposite the first longitudinal end E1), and a return flow channel section RF, extending from the second longitudinal end E2 in the longitudinal direction LR to the coolant outlet AL (i.e., to the first longitudinal end E1). The insert plate EP, together with the base plate BP, encloses the supply flow channel section ZF (at least partially or largely completely, except for openings to be described below), and the cover plate DP encloses the return flow channel section RF (at least partially or largely completely, except for openings to be described below). The insert plate EP has two through-openings DO at its second longitudinal end E2, arranged side by side in the longitudinal direction LR and together extending in the transverse direction QR over almost the entire width of the cooling channel KN, as illustrated in Fig. 2. The through-openings DO serve to convey the coolant from the supply flow channel section ZF to the return flow channel section RF. As can be seen in Fig. 2, the insert plate EP at the first longitudinal end E1 of the cooling channel KN also has a return opening RO, which is designed to direct the coolant from the return flow channel section RF to the coolant outlet AL. The return opening RO extends in the transverse direction QR of the cooling channel KN to the longitudinal axis LA of the cooler KL or the cooling channel KN. In the longitudinal direction LR, the return opening RO has a length L2. The insert plate EP has a sealing wall (not visible in Fig. 2, as it is located below the insert plate EP or between the insert plate EP and the base plate BP) that surrounds the return opening RO at the edges facing away from the coolant outlet AL and extends into the return flow channel section RF to the base plate BP, thus separating the return opening RO from the supply flow channel section ZF in terms of flow technology or sealing it fluid-tight. The geometry of the cooling channel KL, in particular the return flow channel section RF, and the positions and shapes of the two through-holes DO located at the second longitudinal end E2 of the cooling channel KL in the transverse direction QR, and the position and shape of the return opening RO located at the first longitudinal end E1 of the cooling channel KL in the transverse direction QR, result in an asymmetrical flow of the coolant in the return flow channel section RF (illustrated with straight arrows in Fig. 2). This, in turn, leads to a region BR of the return flow channel section RF being poorly or hardly at all exposed to the coolant flow. This region BR extends in the transverse direction QR between the return opening RO and thus the coolant outlet AL, and a channel side wall SW of the cooling channel KN facing away from the coolant outlet AL in the transverse direction QR.In the longitudinal direction LR, the area BR extends from the first longitudinal end E1 to one third of the total length of the return flow channel section RF and has a length or longitudinal extent L1 that is at most three times the length or longitudinal extent L2 of the return opening RO. In this area BR, a turbulent flow region (illustrated in Fig. 2 with a circular segment-shaped arrow) can form, similar to a separation bubble. This region would be separated from, or heavily traversed by, the (usually laminar) main coolant flow in the return flow channel section RF if the insert plate EP did not have a dead-water opening TO (one of several through-holes), which will be described below. This turbulent flow region is located predominantly in the aforementioned area BR and is called the "dead-water region TG." The dead-water region TG leads to poor cooling of the semiconductor switches LH1 located above it, which are shown in Fig.2, which are illustrated with dashed lines for a better description of the solution according to the invention and are located on the area B1 of the surface OF of the cover plate DP, in comparison to the remaining semiconductor switches LH2, which are located above the remaining area of ​​the feedback flow channel section RF or on the area B2 of the surface OF of the cover plate DP, which are also illustrated with dashed lines in Fig. 2. To prevent the formation of this dead water area TG, the insert plate EP has the aforementioned dead water opening TO, which is located above the area BR or the dead water area TG that would be expected without the dead water opening TO and extends through the insert plate EP, thus directly connecting the feed flow channel section ZF with the dead water area TG that would be expected without the dead water opening TO in terms of flow technology. During cooling operation of the cooler KL, a portion of the coolant from the supply flow channel section ZF can flow directly through the dead water opening TO to the dead water area TG that would be expected without the dead water opening TO, thus flowing through the dead water area TG and effectively preventing a turbulent flow similar to a separation bubble and thus a dead water area from forming or persisting in the aforementioned area BR. The insert plate EP also has several bypass openings BO (as additional passage openings) which are designed to allow further parts of the coolant to pass directly from the supply flow channel section ZF without flowing through the passage opening DO directly to the return flow channel section RF. During cooling operation of the cooler KL, additional coolant from the supply flow channel section ZF can flow directly into the return flow channel section RF through the bypass openings BO. There, it mixes with the remaining coolant, which flows from the supply flow channel section ZF through the through-openings DO to the return flow channel section RF and is relatively warm. This results in a largely uniform temperature in the coolant within the return flow channel section RF and reduces the overall pressure drop in the cooling channel. To achieve the most homogeneous mixing of the coolant possible throughout the entire return flow channel section RF, several bypass openings BO are provided, evenly distributed across the entire surface of the insert plate EP. The insert plate EP has a temperature-controlled valve VT at each of the respective bypass openings BO and the dead water opening TO, which are configured to control and / or regulate the coolant flow through the bypass openings BO and the dead water opening TO, depending on coolant temperatures in the supply flow channel section and in the return flow channel section (or depending on local coolant temperatures in their respective channel areas around the respective openings BO, TO) or depending on the temperature difference between these temperatures, i.e., to completely block or partially or completely open the flow through the corresponding openings BO, TO. In this case, the valves VT are designed as temperature-sensitive bimetallic diaphragm valves. These temperature-controlled valves VT allow the entire coolant flow through the return flow channel section RF during the entire cooling operation of the cooler KL to be influenced and controlled with respect to pressure drop, flow velocity, and flow direction within the return flow channel section. The valves VT continuously and automatically change the coolant flow rates through the respective openings BO and TO during the entire cooling operation of the cooler KL, without any active external intervention, and solely based on the coolant temperatures in the respective channel areas around these openings BO and TO. This ensures targeted dynamic mixing of the cooling water, resulting in and maintaining an average cooling water temperature across the entire return flow channel section RF during the entire cooling operation, and effectively prevents the formation of a dead zone.This ensures largely homogeneous cooling of the cover plate DP and thus of the power modules LM or power semiconductor switches LH1 or LH2 arranged on it, despite their placement one behind the other in the direction of coolant flow in the return flow channel section RF. The cover plate DP has a surface-enhancing surface structure with cooler pin fins PF on the underside facing the return flow channel section RF, which are distributed across a surface area of ​​the underside adjacent to the return flow channel section RF and project away from the cover plate DP into the return flow channel section RF and thus extend in the direction of the insert plate EP. The insert plate EP has a flow guide structure on its underside facing the feed flow channel section ZF. This structure comprises two flow guide vanes extending longitudinally LR from the insert plate EP into the feed flow channel section ZF. These flow guide vanes are designed to direct the coolant flowing from the coolant inlet EL or from the bypass channel area UB into the feed flow channel section ZF to the two through-openings DO. The base plate BP has a groove-shaped channel structure RN that runs around the entire perimeter of the plate. Correspondingly, the insert plate EP has a wall structure (not shown in the figures) that runs at least partially around the plate and corresponds to the channel structure RN. This wall structure projects into the channel structure RN, thus creating a fluid-tight connection between the insert plate EP and the base plate BP, and thereby sealing the feed flow channel section ZF in a fluid-tight manner.

Claims

Power electronics cooler (KL) for cooling a power electronics device (LV), comprising: - a base plate (BP) and a top plate (DP) which together enclose a cooling channel (KN) for conveying a coolant, which extends in a longitudinal direction (LR) of the cooler (KL); - a coolant inlet (EL) and a coolant outlet (AL) which are arranged in the longitudinal direction (LR) at a first longitudinal end (E1) of the cooling channel (KN); - an insert plate (EP) which is arranged in the cooling channel (KN) between the base plate (BP) and the top plate (DP) and which divides the cooling channel (KN) into a supply flow channel section (ZF) extending from the coolant inlet (EL) to a second longitudinal end (E2) of the cooling channel (KN) opposite the first longitudinal end (E1) and a return flow channel section (RF) extending from the second longitudinal end (E2) to the coolant outlet (AL);- wherein the insert plate (EP) encloses the supply flow channel section (ZF) with the base plate (BP) and the return flow channel section (RF) with the top plate (DP); - wherein the insert plate (EP) has a through-opening (DO) at its second longitudinal end (E2) for allowing the coolant to pass from the supply flow channel section (ZF) to the return flow channel section (RF); - wherein the insert plate (EP) further has at least one through-opening (BO, TO) for allowing a portion of the coolant to pass directly from the supply flow channel section (ZF) to the return flow channel section (RF);- wherein the insert plate (EP) has a temperature-controlled valve (VT) at the at least one through-hole (BO, TO) which is configured to block or release the coolant flow through the at least one through-hole (BO, TO) depending on coolant temperatures in the supply flow channel section (ZF) and / or in the return flow channel section (RF), - wherein the at least one through-hole (BO, TO) includes a dead water opening (TO) for allowing a portion of the coolant to pass from the supply flow channel section (ZF) directly to a dead water area (TG) of the return flow channel section (RF). Cooler (KL) according to claim 1, wherein the at least one through-hole (BO, TO) further comprises a bypass opening (BO) for allowing a portion of the coolant to pass from the supply flow channel section (ZF) without flowing through the through-hole (DO) directly to the return flow channel section (RF). Cooler (KL) according to one of the preceding claims, wherein the valve (VT) is a diaphragm valve. Cooler (KL) according to one of the preceding claims, wherein the valve (VT) is a bimetallic valve. Cooler (KL) according to one of the preceding claims, wherein the valve (VT) is further configured to block or release the coolant flow through the at least one passage opening (BO, TO) depending on the temperature difference between the coolant temperatures in the supply flow channel section (ZF) and in the return flow channel section (RF). Cooler (KL) according to one of the preceding claims, wherein the valve (VT) is further configured to block or release the coolant flow through the at least one through-hole (BO, TO) depending on local coolant temperatures in the supply flow channel section (ZF) and / or in the return flow channel section (RF) and the temperature difference between these local coolant temperatures. Cooler (KL) according to one of the preceding claims, wherein the valve (VT) is further configured to not release, partially release, or completely release the coolant flow through the at least one through-hole (BO, TO) depending on the coolant temperatures in the supply flow channel section (ZF) and in the return flow channel section (RF) and / or on the temperature difference between these coolant temperatures, and thus to control or regulate the coolant flow through the at least one through-hole (BO, TO). Power electronics device (LV) comprising: - a power module (LM); - a cooler (KL) according to one of the preceding claims; - wherein the power module (LM) is arranged on a surface (OF) of the cover plate (DP) facing away from the return flow channel section (RF) and is thermally contacted with the cover plate (DP). Inverter comprising: - a power electronics device (LV) according to claim 8; - a driver circuit for operating the power electronics device (LV), which is electrically connected to the power module (LM) via signal connections.

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