Cooler

Abstract

A cooler (23) is provided with a cooling plate (241) and a plurality of cooling fins (232). Disposed on one surface of the cooling plate (241) are: a plurality of power semiconductor elements; and an electronic component that generates a different amount of heat than the power semiconductor elements. A refrigerant flow path (231) is formed on the other surface of the cooling plate (241). The direction of extension of the cooling fins (232) is a direction orthogonal to the cooling plate (241). The cooling fins extend from the cooling plate (241) in the direction of extension, and are disposed in the refrigerant flow path (231). The plurality of power semiconductor elements are arranged side-by-side in a prescribed direction. With a direction orthogonal to the prescribed direction serving as the orthogonal direction, the power semiconductor elements and the electronic component are arranged side-by-side in the orthogonal direction. The cooling fins (232) have a shape such that the longitudinal direction is the refrigerant flow direction when viewed from the extension direction. The plurality of cooling fins (232) include inclined fins (233) such that the longitudinal direction thereof is inclined with respect to a prescribed direction.

Description

Cooler CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on Japanese Patent Application No. 2025-053958 filed in Japan on March 27, 2025, and the entire content of the base application is incorporated herein by reference.

[0002] The disclosure in the present specification relates to a cooler.

[0003] Patent Document 1 discloses a heat dissipation structure that cools a plurality of power semiconductor modules with a cooling liquid. Specifically, cooling fins are provided on a cooling plate in contact with the power semiconductor modules, and the power semiconductor modules are cooled by heat exchange between the cooling fins and the cooling liquid.

[0004] Japanese National Publication of International Patent Application No. 2023-510568

[0005] In Patent Document 1, straight ribs and pin ribs are provided on the cooling plate. Thereby, the heat dissipation area is increased while changing the flow of the cooling liquid from laminar flow to turbulent flow. However, there is a limit to the improvement of heat dissipation performance achieved by the above structure.

[0006] One object of the present disclosure is to provide a cooler capable of improving heat dissipation performance.

[0007] A cooler according to one aspect of the present disclosure comprises: a cooling plate, wherein a plurality of power semiconductor elements that generate heat upon energization and an electronic component having a different heat generation amount from the power semiconductor elements are arranged on one surface of the cooling plate, and a coolant flow path for cooling the plurality of power semiconductor elements and the electronic component is formed on the other surface of the cooling plate; and a plurality of cooling fins, wherein a direction orthogonal to the cooling plate is defined as an extension direction, and the cooling fins extend from the cooling plate in the extension direction and are arranged in the coolant flow path, the plurality of power semiconductor elements are arranged side by side in a predetermined direction, a direction orthogonal to the predetermined direction is defined as an orthogonal direction, the power semiconductor elements and the electronic component are arranged side by side in the orthogonal direction, the cooling fins each have a shape in which a coolant flow direction as viewed from the extension direction is a longitudinal direction, and the plurality of cooling fins include inclined fins whose longitudinal direction is inclined with respect to the predetermined direction.

[0008] According to the disclosed cooler, assuming there are no inclined fins, if the direction of refrigerant flow is defined as the main flow direction, the proportion of the area occupied by the portion of the cooling fins through which the refrigerant passes, as viewed from the main flow direction, changes depending on the inclination of the cooling fins with respect to a given direction. In other words, the flow rate of refrigerant flowing between cooling fins that are inclined with respect to a given direction is less than the flow rate of refrigerant flowing between cooling fins that are not inclined with respect to a given direction. This makes it possible to adjust the refrigerant flow rate to be higher in locations that overlap with components that generate a lot of heat, for example, thereby improving the heat dissipation performance of the cooler.

[0009] Another aspect of the disclosure is a cooler comprising: a cooling plate on which a plurality of power semiconductor elements that generate heat when energized and electronic components with different heat generation amounts from the power semiconductor elements are arranged on one side, and a coolant flow path for cooling the plurality of power semiconductor elements and electronic components is formed on the other side; an upper wall facing the cooling plate and forming the coolant flow path; and a plurality of cooling fins whose extension direction is perpendicular to the cooling plate and which extend from the cooling plate in the extension direction and are arranged in the coolant flow path, wherein the plurality of power semiconductor elements are arranged in a line in a predetermined direction, with the direction perpendicular to the predetermined direction being the orthogonal direction, and the power semiconductor elements and electronic components are arranged in a line in the orthogonal direction, and the coolant flow path includes a non-extended region where cooling fins with an extension length of less than a predetermined length are arranged or where no cooling fins are arranged, and an extended region where cooling fins with an extension length of a predetermined length or more are arranged, and the upper wall is provided with a protrusion projecting in the extension direction at a position that overlaps with the non-extended region when viewed from the extension direction.

[0010] According to the disclosed cooler, in the refrigerant flow path, the area through which the refrigerant can pass is small at the location where it overlaps with a protrusion in the extension direction, resulting in a lower flow rate. Therefore, by designing the protrusion to increase the refrigerant flow rate at locations that overlap with components that generate a lot of heat, for example, the optimization of the flow rate distribution can be promoted. Thus, the heat dissipation performance of the cooler is improved.

[0011] Another embodiment of the disclosure is a cooler comprising: a cooling plate on which a plurality of power semiconductor elements that generate heat when energized are arranged on one side, and a coolant flow path for cooling the plurality of power semiconductor elements formed on the other side; a side wall extending in a direction intersecting the cooling plate and surrounding the coolant flow path; an upper wall facing the cooling plate and forming the coolant flow path; and a plurality of cooling fins whose extension direction is perpendicular to the cooling plate and which extend from the cooling plate in the extension direction and are arranged in the coolant flow path, wherein the plurality of power semiconductor elements are arranged in a predetermined direction, and the coolant flow path includes an extension region where cooling fins with an extension direction length of a predetermined length or more are arranged, and a side wall gap region extending in a predetermined direction along the side wall and where cooling fins are not arranged, and the side wall or upper wall is provided with a guide member located in the side wall gap region and guiding the coolant flowing through the side wall gap region to the extension region.

[0012] In the disclosed cooler, cooling fins are not placed in the sidewall gap region, so the coolant, which is at a lower temperature and does not contribute to heat dissipation, tends to flow at a high velocity. In contrast, in the structure of this disclosure, by providing a guide member at a position overlapping with the sidewall gap region, the amount of coolant flowing in the sidewall gap region can be reduced. In other words, the coolant flowing in the sidewall gap region can be directed to a position overlapping with the placement of power semiconductor elements, thereby increasing the coolant flow rate in the extended region. Therefore, optimization of the flow rate distribution can be promoted, and the heat dissipation performance of the cooler is improved.

[0013] The reference numbers in parentheses above are merely examples of correspondences with specific configurations in the embodiments described later, and do not limit the technical scope in any way.

[0014] This figure shows the circuit configuration of a power converter to which the semiconductor device according to the first embodiment is applied. This is a plan view of the cooler as seen from the bottom. This is a plan view of the cooler according to the first embodiment as seen from the top. This is a plan view of the cooler according to the first embodiment as seen from the top. This is an enlarged plan view of the inclined region. This is a cross-sectional view along the line VI-VI in Figure 4. This figure shows the temperature distribution of the refrigerant flowing through the cooler according to the first embodiment. This figure shows the temperature distribution of the refrigerant flowing through the cooler according to a comparative example. This is a plan view of the cooler according to the second embodiment as seen from the top. This is a cross-sectional view along the line X-X in Figure 9. This is a plan view of the cooler according to the third embodiment as seen from the top. This is a cross-sectional view along the line XII-XII in Figure 11. This is a plan view of the cooler according to the fourth embodiment as seen from the top. This is a cross-sectional view along the line XIV-XIV in Figure 13.

[0015] Several embodiments will be described below with reference to the drawings. In each embodiment, the same reference numerals are used for corresponding components, and redundant explanations may be omitted. If only a part of the configuration is described in each embodiment, the configuration of other embodiments described earlier can be applied to the other parts of that configuration. Furthermore, in addition to the combinations of configurations explicitly stated in the description of each embodiment, configurations from multiple embodiments can be partially combined even if not explicitly stated, as long as there are no particular problems with the combination.

[0016] The semiconductor device and semiconductor module comprising the semiconductor device of this embodiment are applied, for example, to a power conversion device for a mobile body that uses a rotating electric machine as a drive source. Examples of mobile bodies include electric vehicles (BEVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), flying vehicles such as electric vertical take-off and landing aircraft and drones, ships, construction machinery, and agricultural machinery. Examples of applications to vehicles will be described below.

[0017] (First Embodiment) First, the general configuration of the vehicle's drive system will be described based on Figure 1.

[0018] <Vehicle Drive System> As shown in Figure 1, the vehicle drive system 1 includes a DC power supply 2, a motor generator 3, and a power converter 4.

[0019] The DC power supply 2 is a DC voltage source composed of rechargeable secondary batteries. The secondary batteries are, for example, lithium-ion batteries or nickel-metal hydride batteries. The motor generator 3 is a three-phase AC rotating electric machine. The motor generator 3 functions as the vehicle's driving source, i.e., an electric motor. The motor generator 3 also functions as a generator during regeneration. The power converter 4 performs power conversion between the DC power supply 2 and the motor generator 3.

[0020] <Power Conversion Device> Next, the circuit configuration of the power conversion device 4 will be described based on Figure 1. The power conversion device 4 is equipped with a power conversion circuit. The power conversion device 4 in this embodiment is equipped with a smoothing capacitor 5 and an inverter 6 which is a power conversion circuit.

[0021] The smoothing capacitor 5 primarily smooths the DC voltage supplied from the DC power supply 2. The smoothing capacitor 5 is connected to the P line 7, which is the high-potential power line, and the N line 8, which is the low-potential power line. The P line 7 is connected to the positive terminal of the DC power supply 2, and the N line 8 is connected to the negative terminal of the DC power supply 2. The positive terminal of the smoothing capacitor 5 is connected to the P line 7 between the DC power supply 2 and the inverter 6. The negative terminal of the smoothing capacitor 5 is connected to the N line 8 between the DC power supply 2 and the inverter 6. The smoothing capacitor 5 is connected in parallel to the DC power supply 2.

[0022] The inverter 6 is a DC-AC conversion circuit. The inverter 6 converts a DC voltage to a three-phase AC voltage according to switching control by a control circuit (not shown) and outputs it to the motor generator 3. This drives the motor generator 3 to generate a predetermined torque. During regenerative braking of the vehicle, the inverter 6 converts the three-phase AC voltage generated by the motor generator 3 in response to the rotational force from the wheels to a DC voltage according to switching control by the control circuit and outputs it to the P line 7. In this way, the inverter 6 performs bidirectional power conversion between the DC power supply 2 and the motor generator 3.

[0023] The inverter 6 is configured with three phase upper and lower arm circuits 9. The upper and lower arm circuits 9 are sometimes referred to as legs. The upper and lower arm circuits 9 each have an upper arm 9H and a lower arm 9L. The upper arm 9H and lower arm 9L are connected in series between the P line 7 and the N line 8, with the upper arm 9H on the P line 7 side.

[0024] The connection point between the upper arm 9H and the lower arm 9L is connected to the corresponding phase winding 3a in the motor generator 3 via the output line 10. Of the upper and lower arm circuits 9, the U-phase upper and lower arm circuit 9U is connected to the U-phase winding 3a via the corresponding output line 10. The V-phase upper and lower arm circuit 9V is connected to the V-phase winding 3a via the corresponding output line 10. The W-phase upper and lower arm circuit 9W is connected to the W-phase winding 3a via the corresponding output line 10. At least a portion of each of the P line 7, N line 8, and output line 10 is made up of conductive material such as a busbar.

[0025] The inverter 6 has six arms. Each arm is equipped with a switching element. The number of switching elements constituting each arm is not particularly limited; there may be one or more. In the case of multiple switching elements, the multiple switching elements connected in parallel to each other are driven on and off at the same timing by a common gate drive signal (drive voltage).

[0026] In this embodiment, an n-channel type MOSFET 11 is used as the switching element constituting each arm. MOSFET is an abbreviation for Metal Oxide Semiconductor Field Effect Transistor. In the upper arm 9H, the drain of the MOSFET 11 is connected to the P line 7. In the lower arm 9L, the source of the MOSFET 11 is connected to the N line 8. The source of the MOSFET 11 in the upper arm 9H and the drain of the MOSFET 11 in the lower arm 9L are interconnected.

[0027] Each MOSFET 11 has a freewheeling diode 12 connected in antiparallel. The diode 12 may be a parasitic diode (body diode) of the MOSFET 11, or it may be a separate diode. The anode of the diode 12 is connected to the source of the corresponding MOSFET 11, and the cathode is connected to the drain.

[0028] Note that the switching element is not limited to MOSFET 11. For example, an IGBT may be used. IGBT is an abbreviation for Insulated Gate Bipolar Transistor. In the case of an IGBT, a freewheeling diode is also connected in antiparallel.

[0029] In addition to the upper and lower arm circuits 9 described above, the inverter 6 is equipped with a snubber circuit 13. The snubber circuit 13 absorbs transient high voltages, so-called switching surges, that occur during switching. This enables high-speed switching. The snubber circuit 13 may be provided individually for each upper and lower arm circuit 9 and connected in parallel to the corresponding upper and lower arm circuits 9. The snubber circuit 13 may be provided individually for each arm 9H, 9L and connected in parallel to the corresponding arms 9H, 9L. As an example, the snubber circuit 13 in this embodiment is connected in parallel to the upper and lower arm circuits 9.

[0030] The snubber circuit 13 has at least a capacitor 131. The snubber circuit 13 may be a C snubber circuit having a capacitor 131, or an RC snubber circuit having a capacitor 131 and a resistor 132 as shown in Figure 1. It may also be an RCD snubber circuit having a capacitor 131, a resistor 132, and a diode.

[0031] The power converter 4 may further include a converter as a power conversion circuit. The converter is a DC-DC converter circuit that converts a DC voltage to, for example, a DC voltage of a different value. The converter is provided between the DC power supply 2 and the smoothing capacitor 5. The converter is configured, for example, with a reactor and the above-described up-and-down arm circuit 9. With this configuration, step-up and step-down voltage conversion is possible. The power converter 4 may also include a filter capacitor to remove power supply noise from the DC power supply 2. The filter capacitor is provided between the DC power supply 2 and the converter.

[0032] The power converter 4 may include a drive circuit for the switching elements that make up the inverter 6, etc. The drive circuit supplies a drive voltage to the gate of the corresponding arm's MOSFET 11 based on a drive command from the control circuit. The drive circuit drives the corresponding MOSFET 11, i.e., turns it on or off, by applying the drive voltage. The drive circuit is sometimes referred to as a driver.

[0033] The power converter 4 may include a control circuit for the switching element. The control circuit generates a drive command for operating the MOSFET 11 and outputs it to the drive circuit. The control circuit generates the drive command based on, for example, a torque request input from a higher-level ECU (not shown) and signals detected by various sensors. ECU is an abbreviation for Electronic Control Unit.

[0034] Various types of sensors include, for example, current sensors, rotation angle sensors, and voltage sensors. The current sensor detects the phase current flowing through the windings 3a of each phase. The rotation angle sensor detects the rotation angle of the rotor of the motor generator 3. The voltage sensor detects the voltage across the smoothing capacitor 5. The control circuit outputs, for example, a PWM signal as a drive command. The control circuit is configured to include, for example, a processor and memory. PWM is an abbreviation for Pulse Width Modulation.

[0035] <Cooler> In the following, the thickness direction of the cooling plate 241 is defined as the Z direction, and the direction perpendicular to the Z direction is defined as the Y direction. The direction perpendicular to both the Z and Y directions is defined as the X direction. The Z direction is perpendicular to the cooling plate 241 and corresponds to the extension direction of the cooling fins 232. The X direction corresponds to a predetermined direction in which the power semiconductor elements 30 are arranged. The Y direction is the direction in which the power semiconductor elements 30 and the snubber circuit 70 are arranged side by side and corresponds to a direction perpendicular to the predetermined direction. Unless otherwise specified, the shape viewed from the Z direction, in other words, the shape along the XY plane defined by the X and Y directions, is referred to as the planar shape. Also, the planar view from the Z direction may simply be referred to as the planar view.

[0036] As shown in Figures 2 to 6, the cooler 23 comprises a cooling plate 241, side walls 242, an upper wall 243, and cooling fins 232. The cooling plate 241 has a lower surface 241b on which a plurality of power semiconductor elements 30 and electronic components with different heat generation amounts from the power semiconductor elements are arranged. The cooling plate 241 has an upper surface 241a on the side opposite to the lower surface 241b, on which a refrigerant flow path is formed.

[0037] Figure 2 is a plan view of the cooler 23 as seen from the lower surface 241b side of the cooling plate 241. As shown in Figure 2, a power semiconductor device 21 and a housing 22 are arranged on the lower surface 241b. The power semiconductor device 21 provides at least one arm of the inverter 6, which is a power conversion circuit. Each of the power semiconductor devices 21 shown in Figure 2 provides an upper and lower arm circuit 9 for one phase. In this embodiment, the inverter 6 is provided by three power semiconductor devices 21. The three power semiconductor devices 21 are arranged side by side in the X direction on the lower surface 241b. Each of the power semiconductor devices 21 is fixed to the cooling plate 241.

[0038] One of the power semiconductor devices 21, power semiconductor device 21U, provides a U-phase up and down arm circuit 9U. Another of the power semiconductor devices 21, power semiconductor device 21V, provides a V-phase up and down arm circuit 9V. Another of the power semiconductor devices 21, power semiconductor device 21W, provides a W-phase up and down arm circuit 9W.

[0039] The power semiconductor device 21 includes, for example, a power semiconductor element 30 and a snubber circuit 70. The power semiconductor element 30 is formed by creating a vertical element on a semiconductor substrate made of materials such as silicon (Si) or a wide-bandgap semiconductor with a wider bandgap than silicon. Examples of wide-bandgap semiconductors include silicon carbide (SiC), gallium nitride (GaN), gallium oxide (Ga2O3), and diamond. The power semiconductor element 30 is sometimes referred to as a power element, semiconductor chip, or semiconductor device.

[0040] The vertical element is configured to carry the main current in the thickness direction of the power semiconductor element 30 (semiconductor substrate). The power semiconductor element 30 is arranged such that its thickness direction is substantially parallel to the Z direction. The power semiconductor element 30 has main electrodes on both sides in the thickness direction. In this embodiment, the power semiconductor element 30 is formed by creating an n-channel type MOSFET 11 as a vertical element on a semiconductor substrate made of SiC.

[0041] When the MOSFET 11 is turned on, a current (main current) flows between the main electrodes, that is, between the drain electrode and the source electrode. The power semiconductor element 30 generates heat as current flows. If the diode 12 is a parasitic diode, the source electrode also serves as the anode electrode, and the drain electrode also serves as the cathode electrode. The diode 12 may be configured on a separate chip from the MOSFET 11. The drain electrode is the main electrode on the high-potential side, and the source electrode is the main electrode on the low-potential side.

[0042] The power semiconductor element 30 has a planar, approximately rectangular shape. The multiple power semiconductor elements 30 include power semiconductor elements 30H that constitute the upper arm 9H and power semiconductor elements 30L that constitute the lower arm. The power semiconductor element 30H is sometimes referred to as the upper arm element. The power semiconductor element 30L is sometimes referred to as the lower arm element. For example, the configurations of the power semiconductor elements 30H and 30L may be common to each other. The multiple power semiconductor elements 30 form a multi-phase upper and lower arm circuit 9.

[0043] The power semiconductor elements 30H and 30L are arranged, for example, in the Y direction. The number of each of the power semiconductor elements 30H and 30L is not particularly limited. There may be one each, or a plurality of each. In the example shown in FIG. 2, the power semiconductor elements 30 include four power semiconductor elements 30H and four power semiconductor elements 30L respectively. The four power semiconductor elements 30H are connected in parallel to provide the MOSFET 11 of the upper arm 9H of one phase. The four power semiconductor elements 30L are connected in parallel to provide the MOSFET 11 of the lower arm 9L of one phase. The four power semiconductor elements 30H are arranged in the X direction. The four power semiconductor elements 30L are arranged in the X direction. Here, "arranged in the X direction" only requires that at least a part of the power semiconductor elements 30H and 30L are arranged in the X direction.

[0044] The snubber circuit 70 includes at least a capacitor 71 as an electronic component. The snubber circuit 70 illustrated in FIG. 2 is an RC snubber circuit. The snubber circuit 70 includes a plurality of resistors 72 in addition to the capacitor 71. The snubber circuit 70 provides the snubber circuit 13 illustrated in FIG. 1. The capacitor 71 provides the capacitor 131, and the resistor 72 provides the resistor 132. The snubber circuit 70 is connected in parallel to the upper and lower arm circuit 9 as described above.

[0045] The snubber circuit 70 is arranged side by side with the power semiconductor element 30 in the Y direction. Here, "arranged in the Y direction" only requires that at least a part of the snubber circuit 70 and at least a part of the power semiconductor element 30 are arranged in the Y direction. In the present embodiment, the snubber circuit 70 corresponds to an electronic component having a different calorific value from that of the power semiconductor element 30. The calorific value of the snubber circuit 70 is smaller than that of the power semiconductor element 30. Note that the snubber circuit 70 may be an RCD snubber circuit. That is, the snubber circuit 70 may include a diode in addition to the capacitor 71 and the resistor 72. Further, the snubber circuit 70 may include a wiring member connected to at least one of the capacitor 71 and the resistor 72. In the example shown in FIG. 2, at least a part of the capacitor 71 or the resistor 72 is arranged side by side with the power semiconductor element 30 in the Y direction. In contrast, the above-described wiring member may be arranged side by side with the power semiconductor element 30 in the Y direction.

[0046] The housing 22 is formed using an electrically insulating material such as resin. The housing 22 may be, for example, a resin molded product. The housing 22 may hold part of the components of the power semiconductor device 21. Part of the components of the power semiconductor device 21 may be integrally molded with the housing 22 as an insert component. The housing 22 may be fixed to the cooling plate 241. The housing 22, while disposed on the lower surface 241b of the cooling plate 241, may together with the cooling plate 241 provide an accommodation space for the power semiconductor device 21. A sealing body that seals the power semiconductor element 30 and the like may be disposed in the accommodation space defined by the housing 22 and the cooling plate 241. The sealing body is, for example, gel or potting resin.

[0047] As illustrated in FIG. 2, the housing 22 may include a frame body 221 and a partition wall 222. The frame body 221 has a height in the Z direction and forms an annular shape so as to surround the power semiconductor device 21 in a plan view in the Z direction. The frame body 221 is sometimes referred to as an annular wall portion. The frame body 221 may have a substantially rectangular annular shape. The rectangular annular frame body 221 has four wall portions 221a, 221b, 221c, 221d.

[0048] The wall portions 221a and 221b extend in the X direction. The wall portion 221a and the wall portion 221b are disposed opposite each other with a predetermined spacing in the Y direction. The wall portion 221a is disposed on one end side of the power semiconductor device 21 in the Y direction, and the wall portion 221b is disposed on the other end side of the power semiconductor device 21. The wall portions 221a and 221b include a wall that defines a region, and an extended portion that extends outward from the wall in the Y direction. The wall portions 221c and 221d extend in the Y direction. The wall portion 221c is connected to the wall portions 221a and 221b at one end side in the X direction. The wall portion 221d is connected to the wall portions 221a and 221b at the other end side in the X direction.

[0049] The partition wall 222 has a predetermined height in the Z direction and is connected to the frame 221. The partition wall 222 divides the area defined by the frame 221 into multiple areas. The partition wall 222 may divide the area into areas corresponding to, for example, the number of power semiconductor devices 21. The partition wall 222 is sometimes referred to as a partition wall. The partition wall 222 may extend in the Y direction, for example, and both ends may be connected to the frame 221. As illustrated in Figures 2 and 3, the housing 22 may have two partition walls 222a and 222b as partition walls 222. The partition walls 222a and 222b extend in the Y direction, similar to the wall portions 221c and 221d. One end of each partition wall 222a and 222b is connected to the wall portion 221a, and the other end is connected to the wall portion 221b. The partition walls 222a, 222b and wall sections 221c, 221d are arranged in the X direction with a predetermined interval between them. The partition wall 222 divides the opposing area of ​​the frame 221 into three regions. A power semiconductor device 21 is housed in each of the three divided regions.

[0050] Figures 3 and 4 are plan views of the cooler 23 as seen from the upper surface 241a side of the cooling plate 241. In Figures 3 and 4, the side walls 242 and the top wall 243 are omitted. Also, in Figure 3, the cooling fins 232 are omitted. Figure 5 is an enlarged plan view of a part of the inclined region 233a. Figure 6 is a cross-sectional view along the line VI-VI in Figure 4.

[0051] A refrigerant channel 231 is formed on the upper surface 241a of the cooling plate 241. The cooling plate 241 has a substantially rectangular shape with the X direction as the longitudinal direction and the Y direction as the short direction. The refrigerant channel 231 has a substantially rectangular shape with the X direction as the longitudinal direction and the Y direction as the short direction in a plan view. As shown in Figure 3, the refrigerant channel 231 is provided so as to overlap with at least a part of the power semiconductor device 21 in a plan view. In this specification, when the refrigerant channel 231 is said to be in a position that overlaps with the power semiconductor device 30 when viewed from the Z direction, it means that at least a part of the refrigerant channel 231 is located in the projection range obtained by projecting the power semiconductor device 30 in the Z direction. The same applies in the following description, where overlapping when viewed from a predetermined direction means that a part is located in the projection range in a predetermined direction.

[0052] As shown in Figure 6, a side wall 242 is formed so as to extend in a direction intersecting the cooling plate 241. In this embodiment, the side wall 242 is formed so as to extend in the Z direction from the top surface 241a. An upper wall 243 is provided at a position opposite to the top surface 241a. One end of the side wall 242 is connected to the cooling plate 241, and the other end of the side wall 242 is connected to the upper wall 243. The side wall 242 is connected, for example, to the Y-direction end and the X-direction end of the top surface 241a. The side wall 242 is perpendicular to the cooling plate 241 and the upper wall 243 and surrounds the refrigerant flow path 231. Here, perpendicular means perpendicular within a range that includes manufacturing variations. The side wall 242 and the upper wall 243 may be a single unit. The space enclosed by the cooling plate 241, the side wall 242, and the upper wall 243 becomes the refrigerant flow path 231.

[0053] Refrigerant is supplied to the refrigerant flow path 231 from the direction of arrow F1 in Figure 3 via an introduction pipe (not shown). The refrigerant is distributed in the Y direction in a chamber (not shown), for example. Then, with no variation in flow rate in the Y direction, the refrigerant flows into the refrigerant flow path 231 on the cooling plate 241. The refrigerant that has flowed through the refrigerant flow path 231 is discharged from the cooler 23 in the direction of arrow F2 via an exhaust pipe (not shown). As the refrigerant, a phase-changing refrigerant such as water or ammonia, or a non-phase-changing refrigerant such as ethylene glycol can be used. In this embodiment, a power semiconductor device 21W is positioned in a location that overlaps with the upstream side of the refrigerant flow path 231 in a plan view. A power semiconductor device 21U is positioned in a location that overlaps with the downstream side of the refrigerant flow path 231 in a plan view. A power semiconductor device 21V is positioned between the power semiconductor device 21W and the power semiconductor device 21U.

[0054] As shown in Figure 4, a plurality of cooling fins 232 are arranged on the upper surface 241a of the cooling plate 241. The cooling fins 232 extend from the cooling plate 241 in the Z direction and are arranged in the refrigerant flow path 231. Here, the direction in which the cooling fins 232 extend is not limited to a strictly orthogonal direction (Z direction) with respect to the cooling plate 241, but means an orthogonal direction within a range that includes manufacturing variations. In a plan view from the Z direction, the cooling fins 232 have a shape in which the refrigerant flow direction is the longitudinal direction. For example, in a plan view from the Z direction, the cooling fins 232 have a flattened shape that extends in the direction of refrigerant flow. If the cooling fins 232 have a flattened shape, the direction in which they flatten and extend corresponds to the longitudinal direction. In a plan view from the Z direction, the cooling fins 232 may be elliptical or polygonal.

[0055] The cooling fins 232 include parallel fins 234 whose longitudinal direction is parallel to the X direction and inclined fins 233 whose longitudinal direction is inclined with respect to the X direction. Here, "parallel to the X direction" means parallel within a range that includes manufacturing variations. The density at which the parallel fins 234 are arranged and the density at which the inclined fins 233 are arranged are, for example, the same. That is, the number of parallel fins 234 arranged per unit area is the same as the number of inclined fins 233 arranged per unit area. However, the density at which the parallel fins 234 are arranged and the density at which the inclined fins 233 are arranged may be different.

[0056] In the refrigerant flow path 231, refrigerant flows in the direction of arrow F3 through the parallel region 234a where the parallel fins 234 are located. In the refrigerant flow path 231, refrigerant flows in the direction of arrow F4 through the inclined region 233a where the inclined fins 233 are located. Arrow F3 is parallel to the longitudinal direction of the parallel fins 234. In other words, arrow F3 is parallel to the X direction. Arrow F4 is parallel to the longitudinal direction of the inclined fins 233.

[0057] As shown in Figures 3 and 4, in this embodiment, in plan view, the inclined region 233a and the parallel region 234a have portions aligned with each other in the Y direction. Furthermore, in plan view, the inclined region 233a and the parallel region 234a have portions aligned with each other in the X direction. In this embodiment, in plan view, the parallel region 234a is provided at a position overlapping with the power semiconductor device 21W, but the inclined region 233a is not provided. In plan view, the parallel region 234a and the inclined region 233a are provided aligned with each other in the Y direction at a position overlapping with the power semiconductor device 21V. In plan view, the parallel region 234a and the inclined region 233a are provided aligned with each other in the Y direction at a position overlapping with the power semiconductor device 21U.

[0058] As described above, the power semiconductor element 30 and the snubber circuit 70 are arranged side by side in the Y direction. The inclined region 233a and the parallel region 234a are arranged as follows in the region where they are arranged side by side in the Y direction. The inclined region 233a is provided on the side where the snubber circuit 70 is arranged in the Y direction. The parallel region 234a is provided on the side where the power semiconductor element 30 is arranged in the Y direction. At least a part of the inclined region 233a overlaps with at least a part of the snubber circuit 70 in a plan view. At least a part of the parallel region 234a overlaps with at least a part of the power semiconductor element 30 in a plan view. As shown in Figures 3 and 4, the inclined region 233a is substantially rectangular in a plan view. The parallel region 234a is substantially L-shaped in a plan view.

[0059] The refrigerant flow path 231 includes boundary regions 235a and 235b, which are the regions between the parallel region 234a and the inclined region 233a. To prevent interference between the parallel fins 234 and the inclined fins 233, cooling fins 232 are not present in the boundary regions 235a and 235b.

[0060] Of the boundary regions, the boundary region 235a in the X direction extends in the Y direction. The boundary region 235a in the X direction corresponds to the region between the inclined region 233a and the parallel region 234a, which are aligned in a predetermined direction. At least a portion of the boundary region 235a in the X direction is provided at a position not facing the power semiconductor element 30. Here, a position not facing the power semiconductor element 30 means a position that does not overlap with the power semiconductor element 30 in a plan view.

[0061] The boundary region 235a in the X direction is located in a position that overlaps, for example, with the space between phases of the power semiconductor elements 30 in a plan view. The space between phases of the power semiconductor elements 30 is the region indicated by the symbol A1 in Figure 3. In other words, the space between phases refers to the space between the power semiconductor elements 30 that are closest to adjacent power semiconductor elements 21U, 21V, and 21W, among the power semiconductor elements 30 that form each power semiconductor device 21U, 21V, and 21W. Here, the space between power semiconductor elements 30 does not have to overlap with the power semiconductor elements 30 in the Y direction. In other words, the Y-direction positions of the boundary region 235a and the power semiconductor elements 30 do not have to overlap.

[0062] In this embodiment, a portion of the boundary region 235a in the X direction overlaps with the position of the power semiconductor element 30 in the Y direction. Overlapping with the position of the power semiconductor element 30 in the Y direction means that at least a portion of the power semiconductor element 30 is at the same position in the Y direction as the boundary region. The term "phase interval" may refer, for example, to the space between power semiconductor device 21U and power semiconductor device 21V, or between power semiconductor device 21V and power semiconductor device 21W.

[0063] In this embodiment, the boundary region 235a in the X direction is located in a position that overlaps with the region between the power semiconductor device 21W and the power semiconductor device 21V in a plan view. The upper and lower arm circuit formed by the power semiconductor element 30 closest to the power semiconductor device 21V among the power semiconductor elements 30 forming the power semiconductor device 21W corresponds to the upper and lower arm circuit of the first phase. The upper and lower arm circuit formed by the power semiconductor element 30 closest to the power semiconductor device 21W among the power semiconductor elements 30 forming the power semiconductor device 21V corresponds to the upper and lower arm circuit of the second phase. The boundary region 235a in the X direction is located, for example, in a position that overlaps with the partition wall 222b in a plan view.

[0064] Of the boundary regions, the boundary region 235b in the Y direction extends in the X direction. The boundary region 235b in the Y direction corresponds to the region between the inclined region 233a and the parallel region 234a, which are aligned in orthogonal directions. At least a portion of the boundary region 235b in the Y direction is located in a position that overlaps with the power semiconductor element 30 in a plan view. The boundary region 235b in the Y direction overlaps with, for example, the power semiconductor element 30H which is an upper arm element in a plan view. In this embodiment, the boundary region 235b in the Y direction overlaps with the power semiconductor element 30H that forms the power semiconductor device 21V and the power semiconductor element 30H that forms the power semiconductor device 21U in a plan view.

[0065] The inclined fins 233 are tilted in a direction that promotes the flow of refrigerant from the side where the snubber circuit 70 is located to the side where the power semiconductor element 30 is located. Here, for each inclined fin 233, one end in the longitudinal direction is the upstream end, and the other end in the longitudinal direction is the downstream end. The refrigerant flows from the upstream end to the downstream end. Each inclined fin 233 is tilted at an angle of 0° to 90° with respect to the X direction such that its downstream end faces the side where the power semiconductor element 30 is located.

[0066] As shown in Figure 5, the inclination of the inclined fin 233 with respect to the X direction is defined as the inclination angle θ. The inclination angle θ is 0° in the direction parallel to the X direction. The inclination angle θ is 90° in the direction extending in the Y direction from the side where the snubber circuit 70 is located toward the side where the power semiconductor element 30 is located. In this embodiment, the inclination angle θ is preferably between 10° and 50°. By setting the angle to the above, the effect of promoting the flow of coolant from the side where the snubber circuit 70 is located toward the side where the power semiconductor element 30 is located is promoted. In this embodiment, for example, the inclination angle θ is the same for all inclined fins. However, each inclined fin 233 may have a different inclination angle. Also, the inclination angle θ is not limited to the range of 10° to 50°.

[0067] As shown in Figure 6, when the refrigerant flow path 231 is viewed from the X direction, the area between the cooling fins 232 varies in the Y direction. That is, the area between the cooling fins 232 differs between the parallel region 234a and the inclined region 233a. When the parallel region 234a is viewed from the X direction, the space through which the refrigerant passes between the cooling fins 232 can be seen. On the other hand, when the inclined region 233a is viewed from the X direction, the space through which the refrigerant passes between the cooling fins 232 cannot be seen. Or, when the inclined region 233a is viewed from the X direction, the space through which the refrigerant passes between the cooling fins 232 is smaller than that of the parallel region 234a. That is, in the inclined region 233a, the flow rate of refrigerant flowing in the X direction is less than that of the parallel region 234a.

[0068] Figure 7 shows the temperature distribution of the refrigerant flowing through the refrigerant channel 231 of this embodiment using contour lines. Figure 8 shows the temperature distribution of the refrigerant flowing through the refrigerant channel 231 of the comparative example using contour lines. The density of the dots shown in the figures indicates the temperature, with denser dots indicating higher temperatures and sparser dots indicating lower temperatures. The refrigerant channel 231 of the comparative example does not have a sloped region 233a. In other words, all the cooling fins 232 arranged in the refrigerant channel 231 of the comparative example are parallel fins 234.

[0069] The refrigerant flows from upstream to downstream while cooling the power semiconductor element 30 and the snubber circuit 70. Therefore, as shown in Figures 7 and 8, the refrigerant temperature tends to increase as you move downstream. Because the power semiconductor element 30 generates a large amount of heat, the temperature of the refrigerant flowing over the power semiconductor element 30 tends to rise. As a result, the temperature of the power semiconductor element 30 does not decrease easily as you move downstream. On the other hand, because the snubber circuit 70 generates little heat, the temperature of the refrigerant flowing over the snubber circuit 70 does not rise easily even downstream.

[0070] In this embodiment shown in Figure 7, as described above, a sloped region 233a is provided in a position that overlaps with the snubber circuit 70, which generates less heat. In the sloped region 233a, the refrigerant flows easily in the direction of arrow F4 shown in Figure 4. As a result, a portion of the refrigerant that has flowed through the position overlapping with the snubber circuit 70 is used to cool the power semiconductor element 30 located downstream. Therefore, as shown in Figures 7 and 8, in this embodiment, the refrigerant temperature downstream is lower than in the comparative example.

[0071] In Figures 7 and 8, four power semiconductor elements 30H are connected in parallel to form one upper arm 9H, and four power semiconductor elements 30L are connected in parallel to form one lower arm 9L. However, the number of power semiconductor elements 30H and 30L connected in parallel may be, for example, three of each.

[0072] The inventors conducted diligent studies and obtained the following findings regarding a cooler with three parallel-connected power semiconductor elements 30H and 30L each. It was found that the temperature of the power semiconductor element 30H located at the downstream end was 5°C lower in this embodiment than in the comparative example. Furthermore, it was found that the temperature of the refrigerant flowing at a position overlapping with the power semiconductor element 30H located at the downstream end in a plan view was 3°C lower in this embodiment than in the comparative example. In other words, the cooler 23 of this embodiment can keep the refrigerant temperature low, and consequently further reduce the temperature of the power semiconductor element 30 located downstream.

[0073] <Effects of the First Embodiment> The cooler 23 according to this embodiment comprises a cooling plate 241 and cooling fins 232. On one surface of the cooling plate 241, i.e., the lower surface 241b, a plurality of power semiconductor elements 30 and a snubber circuit 70 with a different heat generation amount than the power semiconductor elements 30 are arranged. The power semiconductor elements 30 are arranged in the X direction, and the power semiconductor elements 30 and the snubber circuit 70 are arranged in the Y direction. On the other surface of the cooling plate 241, i.e., the upper surface 241a, a plurality of cooling fins 232 are arranged extending from the cooling plate 241 in the extension direction (Z direction). The cooling fins 232 have a shape in which the coolant flow direction is the longitudinal direction when viewed from the extension direction. The plurality of cooling fins 232 include inclined fins 233 whose longitudinal direction is inclined with respect to the X direction.

[0074] Here, assuming there are no inclined fins 233, the direction in which the refrigerant flows is defined as the main flow direction. In this case, the main flow direction is parallel to the X direction. According to the above structure, the proportion of the area occupied by the portion through which the refrigerant passes between the cooling fins 232, as viewed from the main flow direction, changes depending on the inclination of the cooling fins 232 with respect to the X direction. In other words, the flow rate of the refrigerant flowing between cooling fins 232 that are inclined with respect to the X direction is less than the flow rate of the refrigerant flowing between cooling fins 232 that are not inclined with respect to the X direction. This makes it possible to adjust the refrigerant flow rate to be higher in positions that overlap with components that generate a large amount of heat, for example, and improves the heat dissipation performance of the cooler 23.

[0075] Furthermore, in this embodiment, the cooling fins 232 of the cooler 23 are tilted to promote the flow of refrigerant from the side where components with low heat generation are located to the side where components with high heat generation are located. In other words, the cooling fins 232 are tilted to promote the flow of refrigerant from the side where the snubber circuit 70 is located to the side where the power semiconductor element 30 is located. As a result, the refrigerant flows along the tilt of the cooling fins 232, which increases the refrigerant flow rate at the location where it overlaps with components with high heat generation. Therefore, the heat dissipation performance of the cooler 23 is improved.

[0076] Furthermore, in this embodiment, the cooling fins 232 include parallel fins 234 whose longitudinal direction is parallel to the X direction. Of the refrigerant flow path 231, the region where the multiple inclined fins 233 are arranged is the inclined region 233a, and the region where the multiple parallel fins 234 are arranged is the parallel region 234a. The refrigerant flow path 231 includes boundary regions 235a and 235b, which are the regions between the inclined region 233a and the parallel region. At least a portion of the boundary region 235a in the X direction is provided at a position not facing the power semiconductor element 30.

[0077] Here, in order to avoid interference between the adjacent inclined fins 233 and parallel fins 234, cooling fins 232 are absent in the boundary regions 235a and 235b. According to the structure of this disclosure, the boundary region 235a in the X direction is provided at a position that does not overlap with the power semiconductor element 30, which generates a large amount of heat. This minimizes the reduction in heat dissipation performance due to the absence of cooling fins in the boundary region 235a, while increasing the coolant flow rate at the position that overlaps with the heat-generating component, as described above.

[0078] Furthermore, in this embodiment, the power semiconductor element 30 forms a multi-phase upper and lower arm circuit 9, and each phase of the multiple power semiconductor elements 30 is arranged in the X direction. Here, in the portion of the refrigerant flow path 231 corresponding to the space between each phase of the power semiconductor element 30, the required refrigerant flow rate is less than in the portion corresponding to the power semiconductor element 30. In view of this, in the structure of this disclosure, at least a portion of the boundary region 235a in the X direction is provided between the phases. Therefore, the aforementioned effect can be obtained, which is to increase the refrigerant flow rate at positions overlapping with components that generate a large amount of heat, while minimizing the reduction in heat dissipation performance due to the absence of cooling fins 232 in the boundary region 235a.

[0079] Furthermore, in this embodiment, at least a portion of the boundary region 235b in the Y direction is located in a position that overlaps with the power semiconductor element 30. Here, a portion of the refrigerant flowing between the inclined fins 233 and a portion of the refrigerant flowing between the parallel fins 234 merge in the boundary region 235b in the Y direction. The flow velocity in the boundary region 235b increases due to the merging of the refrigerants. In other words, the heat exchange efficiency of the boundary region 235b in the Y direction is improved. According to the structure of this disclosure, since the power semiconductor element 30, which generates a large amount of heat, is located in a position that overlaps with the boundary region 235b in the Y direction, the heat dissipation performance of the cooler 23 can be improved.

[0080] (Second Embodiment) This embodiment is a modification based on the preceding embodiment, and the description of the preceding embodiment can be referenced. Figure 9 is a plan view of the cooler 23 according to this embodiment, viewed from the upper surface 241a side of the cooling plate 241. Figure 10 is a cross-sectional view taken along the line X-X in Figure 9.

[0081] In this embodiment, the cooling fins 232 include an extended fin 237 whose length in the Z direction is greater than or equal to a predetermined length, and a shortened fin 236 whose length in the Z direction is less than the predetermined length. In other words, the refrigerant flow path 231 includes an extended region 237a where the extended fins 237 are located, and a shortened region 236b where the shortened fins 236 are located. Note that the shortened fins 236 are not required. In other words, instead of the shortened region 236b, there may be a region where the cooling fins 232 are not located. In the following description, the region where the cooling fins 232 are not located and the shortened region 236b will be collectively referred to as the non-extended region 236a.

[0082] As shown in Figure 9, the non-extended region 236a and the extended region 237a are aligned in the Y direction in a plan view. The non-extended region 236a is located in a position that overlaps with the snubber circuit 70 in the Z direction. The extended region 237a is located in a position that overlaps with the power semiconductor element 30 in the Z direction.

[0083] As shown in Figure 10, the upper wall 243 in this embodiment is provided with a protrusion 243a that projects in the Z direction at a position that overlaps with the non-extended region 236a in the Z direction. The protrusion 243a projects toward the side where the cooling plate 241 is arranged in the Z direction. In other words, the protrusion 243a projects toward the non-extended region 236a in the Z direction. Due to the protrusion 243a, the distance in the Z direction between the tip of the shortened fin 236 and the upper wall 243 is approximately the same as the distance in the Z direction between the tip of the extended fin 237 and the upper wall 243. Note that the shape of the protrusion 243a is not limited by Figure 10. As shown in Figure 10, the protrusion 243a may be rectangular in X direction view. Alternatively, it may be arc-shaped or triangular.

[0084] In the cooler 23 according to this embodiment, the refrigerant flow rate is reduced in the refrigerant flow path 231 at the location where it overlaps with the protrusion 243a in the Z direction because the area through which the refrigerant can pass is small. Also, the refrigerant flow rate in the non-extended region 236a where the shortened fin 236 is provided is less than the refrigerant flow rate in the extended region 237a. As a result, by providing the protrusion 243a in such a way that the refrigerant flow rate is increased at the location where it overlaps with a component that generates a large amount of heat, the optimization of the flow rate distribution can be promoted. Specifically, as shown by arrow F6 in Figure 9, in this embodiment, the refrigerant flow rate is reduced at the location where it overlaps with the snubber circuit which generates a small amount of heat. Conversely, as shown by arrow F5, the refrigerant flow rate can be increased at the location where it overlaps with the power semiconductor element 30 which generates a large amount of heat. Therefore, the heat dissipation performance of the cooler 23 is improved.

[0085] (Third Embodiment) This embodiment is a modification based on the preceding embodiment, and the description of the preceding embodiment can be referenced. Figure 11 is a plan view of the cooler 23 according to this embodiment, viewed from the upper surface 241a side of the cooling plate 241. Figure 12 is a cross-sectional view along the line XII-XII in Figure 11. In this embodiment, the cooling fins 232 include extended fins 237 whose length in the Z direction is greater than or equal to a predetermined length, and shortened fins 236 whose length in the Z direction is less than a predetermined length. That is, the refrigerant flow path 231 includes an extended region 237a where the extended fins 237 are arranged, and a shortened region 236b where the shortened fins 236 are arranged. Note that the shortened fins 236 are not required. That is, the non-extended region 236a may be a region where no cooling fins 232 are arranged, instead of the shortened region 236b.

[0086] As shown in Figure 11, the non-extended region 236a is located in a position that does not overlap with the power semiconductor element 30 and the snubber circuit 70 in a plan view. At least a portion of the extended region 237a overlaps with the power semiconductor element 30 and the snubber circuit 70 in a plan view. The non-extended region 236a is aligned with at least a portion of the extended region 237a in the X direction. The non-extended region 236a is aligned with at least a portion of the extended region 237a in the Y direction. Furthermore, in a plan view, the non-extended region 236a is aligned with the snubber circuit 70 in the X direction. In other words, at least a portion of the non-extended region 236a overlaps with at least a portion of the snubber circuit 70 in the Y direction.

[0087] In this embodiment, two non-extended regions 236a are provided. One non-extended region 236a is located in a position that overlaps with the region between the power semiconductor device 21W and the power semiconductor device 21V in a plan view. The other non-extended region 236a is located in a position that overlaps with, for example, the partition wall 222b in a plan view. The other non-extended region 236a is located in a position that overlaps with the region between the power semiconductor device 21V and the power semiconductor device 21U in a plan view. The other non-extended region 236a is located in a position that overlaps with, for example, the partition wall 222a in a plan view.

[0088] As shown in Figure 12, the upper wall 243 in this embodiment is provided with a projection 243b that protrudes in the Z direction at a position that overlaps with the non-extended region 236a in the Z direction. The projection 243b corresponds to a convex portion that protrudes in the extension direction. The projection 243b protrudes toward the side where the cooling plate 241 is arranged in the Z direction. In other words, the projection 243b protrudes toward the non-extended region 236a in the Z direction. In this embodiment, the projection 243b protrudes toward the shortened fin 236 in the Z direction.

[0089] The projection 243b is, for example, triangular in view in the Y direction. As shown in Figure 12, the projection 243b may be a right triangle with the upstream side being the hypotenuse in view in the Y direction. By making it triangular, for example, pressure loss of the refrigerant can be suppressed. The tip of the projection 243b may be, for example, arc-shaped. Note that the shape of the projection 243b is not limited to a triangular shape. The projection 243b may be, for example, rectangular in view in the Y direction. As shown in Figure 12, a part of the projection 243b may overlap with a part of each extension fin 237 in the Z direction.

[0090] According to the above structure, the area through which the refrigerant can pass is reduced by the projection 243b at the position that overlaps with the non-extended region 236a in a plan view. As a result, the refrigerant flow rate can be reduced at the position that overlaps with the snubber circuit 70, which generates little heat in the Z direction, and increased at the position that overlaps with the power semiconductor element 30, which generates a lot of heat. In other words, the refrigerant flowing in the direction of arrow F7 is divided by the projection 243b into refrigerant flowing in the direction of arrow F8 and refrigerant flowing in the direction of arrow F9. Thus, the heat dissipation performance is improved.

[0091] (Fourth Embodiment) This embodiment is a modification based on the preceding embodiment, and the description of the preceding embodiment can be referenced. Figure 13 is a plan view of the cooler 23 according to this embodiment, viewed from the upper surface 241a side of the cooling plate 241. Figure 14 is a cross-sectional view along the line XIV-XIV in Figure 13. In this embodiment, the refrigerant flow path 231 includes an extended region 237a, a non-extended region 236a, and a side wall gap region 238a.

[0092] The extended region 237a is the region where extended fins 237, which are cooling fins 232 with a length in the Z direction equal to or greater than a predetermined length, are arranged. The side wall gap region 238a is the region that extends along the side wall 242 in the X direction. No cooling fins 232 are arranged in the side wall gap region 238a. The non-extended region 236a is the region connected to the side wall gap region 238a. No cooling fins 232 are arranged in the non-extended region 236a. Note that shortened fins 236, which are cooling fins 232 with a length in the Z direction less than a predetermined length, may be arranged in the non-extended region 236a.

[0093] At least a portion of the extended region 237a overlaps with the power semiconductor element 30 and the snubber circuit 70 in a plan view. The sidewall gap region 238a does not overlap with the power semiconductor element 30 and the snubber circuit 70 in a plan view. The non-extended region 236a overlaps with at least a portion of the extended region 237a in the Y direction. In other words, the non-extended region 236a is aligned with at least a portion of the extended region 237a in the X direction. At least a portion of the non-extended region 236a is located in a position that overlaps with, for example, the region between adjacent power semiconductor devices 21U, 21V, and 21W in a plan view.

[0094] In this embodiment, there is a non-extended region 236a in a position that overlaps in a plan view between the power semiconductor device 21W and the power semiconductor device 21V, and between the power semiconductor device 21V and the power semiconductor device 21U. As shown in Figure 13, in the Y direction, there may be a non-extended region 236a on both the side where the snubber circuit 70 is located and the side where the power semiconductor element 30 is located. In this embodiment, there are two non-extended regions 236a in each position that overlaps with the power semiconductor devices 21U, 21V, and 21W. In other words, there are four non-extended regions 236a in total.

[0095] As shown in Figure 13, a guide member 242a is provided on the side wall 242. The guide member 242a is located in the side wall gap region 238a and guides the refrigerant flowing through the side wall gap region 238a to the extension region 237a. The guide member 242a may also be located in the non-extension region 236a. In this embodiment, four guide members 242a are provided, located in the side wall gap region 238a and the non-extension region 236a. The extension region 237a is located on both sides of each guide member in the X direction. That is, as shown in Figure 14, at least a portion of each guide member 242a overlaps in the Y direction with at least a portion of the extension region 237a. That is, at least a portion of each guide member 242a is aligned in the X direction with at least a portion of the extension region 237a.

[0096] The guide member 242a has a triangular shape in plan view, for example. As shown in Figure 13, in this embodiment, it has a right-angled triangular shape such that the upstream side is the hypotenuse in plan view. By making it triangular, for example, pressure loss of the refrigerant can be suppressed. The tip of the guide member 242a may be, for example, arc-shaped. Note that the shape of the guide member 242a is not limited to a triangular shape. The guide member 242a may be, for example, rectangular in plan view.

[0097] In this configuration, since no cooling fins 232 are located in the sidewall gap region 238a, the coolant, which is at a lower temperature and does not contribute to heat dissipation, tends to flow at a high velocity. In contrast, in this embodiment, by providing a guide member 242a at a position overlapping with the sidewall gap region 238a, the flow rate of the coolant flowing through the sidewall gap region 238a can be reduced. In other words, the coolant flowing through the sidewall gap region 238a can be directed to a position overlapping with the locations of the power semiconductor elements 30 and the snubber circuit 70, thereby increasing the coolant flow rate in the extension region 237a. Furthermore, in this embodiment, the guide member 242a is positioned between the extension regions 237a. This further increases the coolant flow rate guided from the sidewall gap region 238a to the extension region 237a. Thus, optimization of the flow rate distribution can be promoted, and the heat dissipation performance of the cooler is improved.

[0098] In this embodiment, the guide member 242a is provided on the side wall 242. However, the guide member 242a may also be provided on the upper wall 243. In this case as well, the guide member 242a is located in the side wall gap region 238a in a plan view. Furthermore, the number and position of the guide members 242a are not limited by Figures 13 and 14.

[0099] (Other Embodiments) The disclosures of this specification are not limited to the exemplary embodiments. The disclosures encompass the exemplary embodiments and variations thereof by those skilled in the art. For example, the disclosures are not limited to the combinations of parts and elements shown in the embodiments, but can be implemented in various variations. The disclosures can be implemented in a variety of combinations. The disclosures may have additional parts that can be added to the embodiments. The disclosures encompass embodiments in which parts and elements have been omitted. The disclosures encompass substitutions or combinations of parts and elements between one embodiment and another. The scope of the disclosed technical field is not limited to the descriptions of the embodiments. The scope of the disclosed technical field is indicated by the claims and should be understood to include all modifications within the meaning and scope equivalent to the claims.

[0100] The disclosures in the specification and drawings are not limited by the claims. The disclosures in the specification and drawings encompass the technical ideas described in the claims and extend to a wider and more diverse range of technical ideas than those described in the claims. Therefore, a variety of technical ideas can be extracted from the disclosures in the specification and drawings without being bound by the claims.

[0101] When an element or layer is referred to as “on top of,” “connected to,” “linked to,” or “joined,” it may be directly on top of, connected to, or joined to another element or layer, and there may also be an intervening element or layer. In contrast, when an element is referred to as “directly on top of,” “directly connected to,” “directly linked to,” or “directly joined to” another element or layer, there is no intervening element or layer. Other words used to describe relationships between elements should be interpreted in a similar manner (e.g., “between” vs. “directly between,” “adjacent” vs. “directly adjacent,” etc.). As used in this specification, the term “and / or” includes any combination and all combinations relating to one or more of the enumerated items in question. That is, the statement A and / or B means at least one of A and B.

[0102] Spatially relative terms such as "inside," "outside," "back," "below," "low," "above," and "high" are used here to facilitate descriptions of the relationship between one element or feature and other elements or features, as illustrated. Spatially relative terms may be intended to encompass different orientations of the device in use or operation, in addition to the orientation depicted in the drawings. For example, if the device in the drawing is turned upside down, an element described as "below" or "directly below" another element or feature will be oriented "above" the other element or feature. Thus, the term "below" can encompass both up and down orientations. The device may be oriented in other directions, or rotated 90 degrees or in other directions, and the spatially relative descriptors used in this specification will be interpreted accordingly.

[0103] In the first embodiment described above, the boundary region 235a in the X direction is located in a position that overlaps with the region between the power semiconductor device 21W and the power semiconductor device 21V in a plan view, but it may be located in other positions. For example, the boundary region 235a in the X direction may be located in a position that overlaps with the region between the power semiconductor device 21V and the power semiconductor device 21U in a plan view. In this case, the upper and lower arm circuit formed by the power semiconductor element 30 closest to the power semiconductor device 21U among the power semiconductor elements 30 forming the power semiconductor device 21V corresponds to the upper and lower arm circuit of the first phase. The upper and lower arm circuit formed by the power semiconductor element 30 closest to the power semiconductor device 21V among the power semiconductor elements 30 forming the power semiconductor device 21U corresponds to the upper and lower arm circuit of the second phase.

[0104] Alternatively, the boundary region 235a in the X direction may be omitted. In other words, the parallel region 234a and the inclined region 233a may be arranged side by side in the Y direction at positions overlapping with each power semiconductor device 21. The inclination angle θ may be changed depending on the position of the boundary region 235a in the X direction. For example, if there is no boundary region 235a in the X direction, the inclination angle θ may gradually increase from the upstream side to the downstream side.

[0105] In the first embodiment described above, the boundary region 235b in the Y direction is located in a position that overlaps with the power semiconductor element 30 in a plan view, but it may be located in other positions. For example, the boundary region 235b in the Y direction may be located in a position that overlaps with the region between power semiconductor element 30H and power semiconductor element 30L. Alternatively, it may be located in a position that overlaps with the region between power semiconductor element 30 and snubber circuit 70.

[0106] In this embodiment, a snubber circuit 70 is provided as a component with a different heat generation capacity than the power semiconductor element 30. However, other electronic components besides the snubber circuit 70 may be provided. For example, a filter circuit, a Y capacitor, a discharge resistor, etc., may be provided instead of the snubber circuit 70. In this case, the filter circuit, Y capacitor, and discharge resistor correspond to electronic components with a different heat generation capacity than the power semiconductor element 30.

[0107] (Disclosure of Technical Ideas) This specification discloses several technical ideas as described in the following paragraphs. Some paragraphs may be written in a multiple dependent form, where subsequent paragraphs optionally refer to preceding paragraphs. Furthermore, some paragraphs may be written in a multiple dependent form, where they refer to other multiple dependent forms. These paragraphs written in multiple dependent forms define several technical ideas.

[0108] (Technical Concept 1) A cooler comprising: a cooling plate (241) on which a plurality of power semiconductor elements (30) that generate heat when energized and electronic components (70) with different heat generation amounts from the power semiconductor elements are arranged on one side, and a refrigerant flow path (231) for cooling the plurality of power semiconductor elements and the electronic components is formed on the other side; and a plurality of cooling fins (232) which have an extension direction perpendicular to the cooling plate as their extension direction and extend from the cooling plate in the extension direction and are arranged in the refrigerant flow path, wherein the plurality of power semiconductor elements are arranged in a line in a predetermined direction, the direction perpendicular to the predetermined direction is considered an orthogonal direction, and the power semiconductor elements and the electronic components are arranged in a line in the orthogonal direction, the cooling fins have a shape in which the refrigerant flow direction is the longitudinal direction when viewed from the extension direction, and the plurality of cooling fins include inclined fins (233) whose longitudinal direction is inclined with respect to the predetermined direction.

[0109] (Technical Concept 2) The cooler according to Technical Concept 1, wherein the inclined fins are tilted in a direction that promotes the flow of coolant from the side where components with low heat generation are located to the side where components with high heat generation are located among the plurality of power semiconductor elements and electronic components.

[0110] (Technical Concept 3) The cooling device according to Technical Concept 1 or 2, wherein the heat generated by the plurality of power semiconductor elements is greater than that of the electronic components, the plurality of cooling fins include parallel fins (234) whose longitudinal direction is parallel to the predetermined direction, the refrigerant flow path includes an inclined region (233a) where the plurality of inclined fins are arranged, a parallel region (234a) where the plurality of parallel fins are arranged, and boundary regions (235a, 235b) which are the regions between the inclined region and the parallel region, and at least a portion of the boundary region between the inclined region and the parallel region, which are aligned in the predetermined direction, is provided at a position not facing the power semiconductor elements.

[0111] (Technical Concept 4) The cooler according to Technical Concept 3, wherein a plurality of power semiconductor elements form a plurality of phase upper and lower arm circuits (9), the plurality of phase upper and lower arm circuits are arranged in a predetermined direction, and at least a portion of the boundary region between the inclined region and the parallel region arranged in the predetermined direction is provided between the upper and lower arm circuits of the first phase and the upper and lower arm circuits of the second phase of the plurality of phases.

[0112] (Technical Idea 5) The cooling device according to Technical Idea 1 or 2, wherein the heat generated by the power semiconductor element is greater than that of the electronic component, the plurality of cooling fins include parallel fins (234) whose longitudinal direction is parallel to the predetermined direction, the refrigerant flow path includes an inclined region (233a) where a plurality of inclined fins are arranged, a parallel region (234a) where a plurality of parallel fins are arranged, and boundary regions (235a, 235b) which are the region between the inclined region and the parallel region, the inclined region and the parallel region are arranged side by side in the orthogonal direction, and at least a portion of the boundary region between the inclined region and the parallel region which are arranged side by side in the orthogonal direction is provided in a position that overlaps with the power semiconductor element when viewed from the extension direction.

[0113] (Technical Idea 6) A cooler according to any one of Technical Ideas 1 to 5, having an upper wall (243) facing the cooling plate and forming the refrigerant flow path, wherein the refrigerant flow path includes a non-extended region (236a) in which the cooling fins having a length in the extension direction less than a predetermined length are arranged, or in which the cooling fins are not arranged, and an extended region (237a) in which the cooling fins having a length in the extension direction of the predetermined length or longer are arranged, and the upper wall is provided with protrusions (243a, 243b) projecting in the extension direction at positions that overlap with the non-extended region when viewed from the extension direction.

[0114] (Technical Idea 7) A cooler according to any one of Technical Ideas 1 to 5, having a side wall (242) that extends in a direction intersecting the cooling plate and surrounds the refrigerant flow path, and an upper wall (243) that faces the cooling plate and forms the refrigerant flow path, wherein the refrigerant flow path includes an extension region (237a) in which the cooling fins having a length in the extension direction of a predetermined length or more are arranged, and a side wall gap region (238a) that extends along the side wall in the direction of refrigerant flow and in which the cooling fins are not arranged, and a guide member (242a) located in the side wall gap region and guiding the refrigerant flowing through the side wall gap region to the extension region.

[0115] (Technical Concept 8) A cooling plate (241) on which a plurality of power semiconductor elements (30) that generate heat when energized and electronic components (70) with different heat generation amounts from the power semiconductor elements are arranged on one side, and a refrigerant flow path (231) for cooling the plurality of power semiconductor elements and the electronic components is formed on the other side; an upper wall (243) facing the cooling plate and forming the refrigerant flow path; a plurality of cooling fins (232) whose extension direction is perpendicular to the cooling plate and which extend from the cooling plate in the extension direction and are arranged in the refrigerant flow path; the plurality of power semiconductor elements are arranged in a line in a predetermined direction, the direction perpendicular to the predetermined direction is the orthogonal direction, and the power semiconductor elements and the electronic components are arranged in a line in the orthogonal direction; the refrigerant flow path includes a non-extended region (236a) where the cooling fins whose length in the extension direction is less than a predetermined length are arranged, or where the cooling fins are not arranged; and an extended region (237a) where the cooling fins whose length in the extension direction is equal to or greater than the predetermined length are arranged. The upper wall is provided with protrusions (243a, 243b) that project in the direction of extension, at positions that overlap with the non-extended region when viewed from the direction of extension.

[0116] (Technical Concept 9) The cooler according to Technical Concept 8, wherein the heat generated by the power semiconductor element is greater than that of the electronic component, the non-extended region includes a shortened region (236b) in which the cooling fins of less than a predetermined length are arranged, and at least a portion of the shortened region is provided in a position that overlaps with the electronic component when viewed from the extension direction.

[0117] (Technical Concept 10) The cooler according to Technical Concept 8, wherein the heat generated by the power semiconductor element is greater than that of the electronic component, and the non-extended region is located in a position that does not overlap with the power semiconductor element and the electronic component when viewed from the extension direction, and is aligned with the electronic component in the predetermined direction.

[0118] (Technical Concept 11) A cooling plate (241) on which a plurality of power semiconductor elements (30) that generate heat when energized are arranged on one side and a refrigerant flow path (231) for cooling the plurality of power semiconductor elements is formed on the other side; a side wall (242) extending in a direction intersecting the cooling plate and surrounding the refrigerant flow path; an upper wall (243) facing the cooling plate and forming the refrigerant flow path; a plurality of cooling fins (232) whose extension direction is perpendicular to the cooling plate and which extend from the cooling plate in the extension direction and are arranged in the refrigerant flow path, wherein the plurality of power semiconductor elements are arranged in a predetermined direction, and the refrigerant flow path includes an extension region (237a) in which the cooling fins having a length in the extension direction of a predetermined length or more are arranged, and a side wall gap region (238a) extending along the side wall in the predetermined direction and in which the cooling fins are not arranged. A cooler in which a guide member (242a) is provided on the side wall or the upper wall, located in the side wall gap region, and guides the refrigerant flowing through the side wall gap region to the extension region.

[0119] (Technical Concept 12) The cooler according to technical concept 11, wherein the refrigerant flow path includes a non-extended region (236a) that is connected to the side wall gap region and in which the cooling fins are less than the predetermined length or in which no cooling fins are arranged, and the guide member is also located in the non-extended region such that the extended region is located on both sides of the guide member in the predetermined direction.

Claims

1. A cooler comprising: a cooling plate (241) on which a plurality of power semiconductor elements (30) that generate heat when energized and electronic components (70) with different heat generation amounts than the power semiconductor elements are arranged on one side, and a refrigerant flow path (231) for cooling the plurality of power semiconductor elements and the electronic components is formed on the other side; and a plurality of cooling fins (232) whose extension direction is perpendicular to the cooling plate and which extend from the cooling plate in the extension direction and are arranged in the refrigerant flow path, wherein the plurality of power semiconductor elements are arranged in a line in a predetermined direction, the direction perpendicular to the predetermined direction is considered an orthogonal direction, and the power semiconductor elements and the electronic components are arranged in a line in the orthogonal direction, the cooling fins have a shape in which the refrigerant flow direction is the longitudinal direction when viewed from the extension direction, and the plurality of cooling fins include inclined fins (233) whose longitudinal direction is inclined with respect to the predetermined direction.

2. The cooler according to claim 1, wherein the inclined fins are tilted in a direction that promotes the flow of coolant from the side where components with low heat generation are located to the side where components with high heat generation are located among the plurality of power semiconductor elements and electronic components.

3. The heat generated by the plurality of power semiconductor elements is greater than that of the electronic components, the plurality of cooling fins include parallel fins (234) whose longitudinal direction is parallel to the predetermined direction, the coolant flow path includes an inclined region (233a) where the plurality of inclined fins are arranged, a parallel region (234a) where the plurality of parallel fins are arranged, and boundary regions (235a, 235b) which are the regions between the inclined region and the parallel region, and at least a portion of the boundary region between the inclined region and the parallel region which are aligned in the predetermined direction is provided at a position not facing the power semiconductor elements, as described in claim 1 or 2.

4. The cooler according to claim 3, wherein the plurality of power semiconductor elements form a plurality of phase upper and lower arm circuits (9), the plurality of phase upper and lower arm circuits are arranged in a predetermined direction, and at least a portion of the boundary region between the inclined region and the parallel region arranged in the predetermined direction is provided between the upper and lower arm circuit of the first phase and the upper and lower arm circuit of the second phase of the plurality of phases.

5. The power semiconductor element generates more heat than the electronic component, the plurality of cooling fins include parallel fins (234) whose longitudinal direction is parallel to the predetermined direction, the coolant flow path includes an inclined region (233a) where a plurality of inclined fins are arranged, a parallel region (234a) where a plurality of parallel fins are arranged, and boundary regions (235a, 235b) which are the region between the inclined region and the parallel region, the inclined region and the parallel region are arranged side by side in the orthogonal direction, and at least a portion of the boundary region between the inclined region and the parallel region which are arranged side by side in the orthogonal direction is provided in a position that overlaps with the power semiconductor element when viewed from the extension direction, as described in claim 1 or 2.

6. The cooler according to claim 1 or 2, having an upper wall (243) facing the cooling plate and forming the refrigerant flow path, wherein the refrigerant flow path includes: a non-extended region (236a) where the cooling fins having a length in the extension direction less than a predetermined length are arranged, or where the cooling fins are not arranged; and an extended region (237a) where the cooling fins having a length in the extension direction equal to or greater than the predetermined length are arranged, and the upper wall is provided with protrusions (243a, 243b) projecting in the extension direction at positions that overlap with the non-extended region when viewed from the extension direction.

7. The cooler according to claim 1 or 2, having a side wall (242) extending in a direction intersecting the cooling plate and surrounding the refrigerant flow path, and an upper wall (243) facing the cooling plate and forming the refrigerant flow path, wherein the refrigerant flow path includes an extension region (237a) where the cooling fins having a length in the extension direction of a predetermined length or more are arranged, and a side wall gap region (238a) extending along the side wall in the direction of refrigerant flow and not having the cooling fins arranged, and a guide member (242a) located in the side wall gap region for guiding the refrigerant flowing through the side wall gap region to the extension region.

8. A cooling plate (241) on which a plurality of power semiconductor elements (30) that generate heat when energized and electronic components (70) with different heat generation amounts than the power semiconductor elements are arranged on one side, and a refrigerant flow path (231) for cooling the plurality of power semiconductor elements and the electronic components is formed on the other side; an upper wall (243) facing the cooling plate and forming the refrigerant flow path; a plurality of cooling fins (232) whose extension direction is perpendicular to the cooling plate and which extend from the cooling plate in the extension direction and are arranged in the refrigerant flow path; the plurality of power semiconductor elements are arranged in a line in a predetermined direction, the direction perpendicular to the predetermined direction is the orthogonal direction, and the power semiconductor elements and the electronic components are arranged in a line in the orthogonal direction; the refrigerant flow path includes a non-extended region (236a) where the cooling fins whose length in the extension direction is less than a predetermined length are arranged, or where the cooling fins are not arranged; and an extended region (237a) where the cooling fins whose length in the extension direction is equal to or greater than the predetermined length are arranged. The upper wall is provided with protrusions (243a, 243b) that project in the direction of extension, at positions that overlap with the non-extended region when viewed from the direction of extension.

9. The cooler according to claim 8, wherein the heat generated by the power semiconductor element is greater than that of the electronic component, the non-extended region includes a shortened region (236b) in which the cooling fins of less than a predetermined length are arranged, and at least a portion of the shortened region is provided in a position that overlaps with the electronic component when viewed from the extension direction.

10. The cooler according to claim 8, wherein the heat generated by the power semiconductor element is greater than that of the electronic component, and the non-extended region is located in a position that does not overlap with the power semiconductor element and the electronic component when viewed from the extension direction, and is aligned with the electronic component in the predetermined direction.

11. A cooling plate (241) on which a plurality of power semiconductor elements (30) that generate heat when energized are arranged on one side, and a refrigerant flow path (231) for cooling the plurality of power semiconductor elements is formed on the other side; a side wall (242) extending in a direction intersecting the cooling plate and surrounding the refrigerant flow path; an upper wall (243) facing the cooling plate and forming the refrigerant flow path; a plurality of cooling fins (232) whose extension direction is perpendicular to the cooling plate and which extend from the cooling plate in the extension direction and are arranged in the refrigerant flow path, wherein the plurality of power semiconductor elements are arranged in a predetermined direction, and the refrigerant flow path includes an extension region (237a) in which the cooling fins having a length in the extension direction of a predetermined length or more are arranged, and a side wall gap region (238a) extending along the side wall in the predetermined direction and in which the cooling fins are not arranged. A cooler in which a guide member (242a) is provided on the side wall or the upper wall, located in the side wall gap region, and guides the refrigerant flowing through the side wall gap region to the extension region.

12. The cooler according to claim 11, wherein the refrigerant flow path includes a non-extended region (236a) that is connected to the side wall gap region, wherein the cooling fins are less than the predetermined length or the cooling fins are not arranged, and the guide member is also located in the non-extended region such that the extended region is located on both sides of the guide member in the predetermined direction.

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