Electrical device
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- DENSO CORP
- Filing Date
- 2025-12-23
- Publication Date
- 2026-07-30
Smart Images
Figure JP2025045169_30072026_PF_FP_ABST
Abstract
Description
Electrical device Cross-reference to related applications
[0001] This application is based on Japanese Patent Application No. 2025-008738 filed in Japan on January 21, 2025, and the contents of the base application are incorporated herein by reference in their entirety.
[0002] The disclosure described in this specification relates to an electrical device.
[0003] The electrical device of Patent Document 1 includes a first cooler, a semiconductor module, a second cooler, and a pressing member. The semiconductor module is provided between the first cooler and the second cooler. The pressing member is provided on the opposite side of the semiconductor module via the second cooler. The pressing member presses the second cooler from the surface opposite to the semiconductor module toward the semiconductor module side. The pressing member includes a pressing plate and an elastic member. The elastic member is disposed between the pressing plate and the second cooler. By fixing the pressing plate at a predetermined position with respect to the case, the elastic member is elastically deformed. Due to the reaction force of the elastic deformation, the second cooler is pressed against the semiconductor module.
[0004] Japanese Unexamined Patent Application Publication No. 2024-117421
[0005] In Patent Document 1, a configuration in which the elastic member directly contacts the second cooler is described. In this configuration, the reaction force due to the elastic deformation of the elastic member tends to act locally on the second cooler and is unlikely to act uniformly on the second cooler. Accordingly, unevenness has occurred in the contact state between the second cooler and the semiconductor module.
[0006] An object of the present disclosure is to provide an electrical device in which unevenness in the contact state between the second cooler and the semiconductor module is suppressed.
[0007] An electrical device according to one aspect of the present disclosure comprises: a plurality of semiconductor modules having one surface and a back surface spaced apart in the thickness direction and arranged in one direction perpendicular to the thickness direction; a first cooler for cooling the plurality of semiconductor modules from the back side; a second cooler for cooling the plurality of semiconductor modules from one surface side; and a pressing member that overlaps the second cooler in the thickness direction and presses the second cooler against the plurality of semiconductor modules, wherein the pressing member comprises: a back plate that overlaps the second cooler; a fixing plate provided on the opposite side from the second cooler via the back plate and fixed at a position a predetermined distance away from the back plate in the thickness direction; and an elastic member sandwiched between the back plate and the fixing plate and pressing the back plate against the second cooler by a reaction force due to deformation.
[0008] The backplate prevents the reaction force of the elastic member from acting locally on the second cooler. The reaction force of the elastic member becomes more uniform on the second cooler. Consequently, pressure is more uniformly applied from the second cooler to the multiple semiconductor modules. This suppresses unevenness in the contact state between the second cooler and the multiple semiconductor modules depending on the location.
[0009] The reference numbers in parentheses above merely indicate the correspondence with the configurations described in the embodiments below, and do not in any way limit the technical scope.
[0010] This figure shows the circuit configuration and drive system of the electrical device. This is a plan view of the electrical device. This is a plan view of the electrical device with the pressing member removed from Figure 2. This is a cross-sectional view along the line IV-IV in Figure 2. This is an exploded perspective view of the pressing member. This is a cross-sectional view along the line VI-VI in Figure 2. This is a plan view of the elastic member.
[0011] 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.
[0012] The electrical device of this embodiment is applied, for example, to a mobile body that uses a rotating electric machine as a drive source. Examples of mobile bodies include electric vehicles such as electric electric vehicles (BEVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs), electric aircraft such as drones and electric vertical take-off and landing aircraft (eVTOLs), ships, construction machinery, and agricultural machinery. Examples of application to vehicles will be described below. The electrical device may also be applied to, for example, a power converter, a battery device, a charging device, or a junction box.
[0013] (First Embodiment) First, the schematic configuration of the vehicle's drive system will be described based on Figure 1.
[0014] <Vehicle Drive System> As shown in Figure 1, the vehicle drive system 1 comprises a DC power supply 2, a motor generator 3, and an electrical device 4.
[0015] The DC power supply 2 is a DC voltage source composed of a rechargeable secondary battery. Examples of secondary batteries include lithium-ion batteries, nickel-metal hydride batteries, and organic radical 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. During regeneration, the motor generator 3 functions as a generator. The electrical device 4 performs power conversion between the DC power supply 2 and the motor generator 3.
[0016] <Circuit Configuration of the Electrical Device> Figure 1 shows the circuit configuration of the electrical device 4. The electrical device 4 includes at least a power conversion circuit. In this embodiment, the power conversion circuit is an inverter 5. The electrical device 4 may further include a smoothing capacitor 6, a drive circuit 7, etc. The electrical device 4 is sometimes referred to as a power conversion device.
[0017] The smoothing capacitor 6 primarily smooths the DC voltage supplied from the DC power supply 2. The smoothing capacitor 6 is connected to the P line 8, which is the high-potential power supply line, and the N line 9, which is the low-potential power supply line. The P line 8 is connected to the positive terminal of the DC power supply 2, and the N line 9 is connected to the negative terminal of the DC power supply 2. The positive terminal of the smoothing capacitor 6 is connected to the P line 8 between the DC power supply 2 and the inverter 5. The negative terminal of the smoothing capacitor 6 is connected to the N line 9 between the DC power supply 2 and the inverter 5. The smoothing capacitor 6 is connected in parallel to the DC power supply 2.
[0018] The inverter 5 is a DC-AC conversion circuit. The inverter 5 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 5 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 8. In this way, the inverter 5 performs bidirectional power conversion between the DC power supply 2 and the motor generator 3.
[0019] The inverter 5 is configured with three phase upper and lower arm circuits 10. The upper and lower arm circuits 10 are sometimes referred to as legs. The upper and lower arm circuits 10 each have an upper arm 10H and a lower arm 10L. The upper arm 10H and the lower arm 10L are connected in series between the P line 8 and the N line 9, with the upper arm 10H on the P line 8 side.
[0020] The connection point between the upper arm 10H and the lower arm 10L, i.e., the midpoint of the upper and lower arm circuits 10, is connected to the corresponding phase winding 3a in the motor generator 3 via the output line 11. Of the upper and lower arm circuits 10, the U-phase upper and lower arm circuit 10U is connected to the U-phase winding 3a via the output line 11. The V-phase upper and lower arm circuit 10V is connected to the V-phase winding 3a via the output line 11. The W-phase upper and lower arm circuit 10W is connected to the W-phase winding 3a via the output line 11.
[0021] The upper and lower arm circuits 10 (10U, 10V, 10W) have a series circuit 12. The series circuit 12 in the upper and lower arm circuits 10 may be one or more. If there are multiple series circuits 12, they are connected in parallel to each other to form one phase of the upper and lower arm circuits 10. In this embodiment, each of the upper and lower arm circuits 10 has one series circuit 12. The series circuit 12 is configured by connecting the switching element on the upper arm 10H side and the switching element on the lower arm 10L side in series between the P line 8 and the N line 9.
[0022] The number of high-side switching elements and low-side switching elements constituting the series circuit 12 is not particularly limited. There may be one or more. The series circuit 12 in this embodiment has two switching elements on the high-side and two switching elements on the low-side. The two high-side switching elements are connected in parallel, and the two low-side switching elements are connected in parallel to constitute one series circuit 12. In other words, in the three-phase upper and lower arm circuits 10, each of the six arms 10H and 10L is composed of two switching elements connected in parallel to each other.
[0023] In this embodiment, n-channel type MOSFETs 13 are used as each switching element. MOSFET is an abbreviation for Metal Oxide Semiconductor Field Effect Transistor. The two high-side MOSFETs 13 connected in parallel are turned on and off at the same timing by a common gate drive signal (drive voltage). The two low-side MOSFETs 13 connected in parallel are turned on and off at the same timing by a common gate drive signal (drive voltage).
[0024] Each of the MOSFETs 13 has a freewheeling diode 14 (hereinafter referred to as FWD14) connected in antiparallel. In the case of MOSFET 13, FWD14 may be a parasitic diode (body diode) or an external diode. On the upper arm 10H, the drain of MOSFET 13 is connected to the P line 8. On the lower arm 10L, the source of MOSFET 13 is connected to the N line 9. The drains of MOSFET 13 on the upper arm 10H and the drains of MOSFET 13 on the lower arm 10L are interconnected. The anode of FWD14 is connected to the source of the corresponding MOSFET 13, and its cathode is connected to the drain.
[0025] Note that the switching element is not limited to MOSFET 13. For example, an IGBT may be used. IGBT is an abbreviation for Insulated Gate Bipolar Transistor. In the case of an IGBT, the FWD 14 is also connected in antiparallel.
[0026] The drive circuit 7 drives the switching elements that make up the power conversion circuit, such as the inverter 5. Based on the drive command from the control circuit, the drive circuit 7 supplies a drive voltage to the gate of the corresponding MOSFET 13. By applying the drive voltage, the drive circuit drives the corresponding MOSFET 13, i.e., turns it on or off. The drive circuit is sometimes referred to as a driver.
[0027] The electrical device 4 may include a control circuit for the switching element. The control circuit generates a drive command for operating the MOSFET 13 and outputs it to the drive circuit 7. 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. The control circuit may be located within the higher-level ECU.
[0028] Examples of various sensors include current sensors, rotation angle sensors, and voltage sensors. The electrical device 4 may be equipped with at least one of these 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 6. The control circuit is configured to include, for example, a processor and memory. The control circuit outputs, for example, a PWM signal as a drive command. PWM is an abbreviation for Pulse Width Modulation.
[0029] The electrical device 4 may include a converter as a power conversion circuit. The converter is a DC-DC conversion 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 6. The converter is configured, for example, with a reactor and the above-described up-and-down arm circuit 10. With this configuration, step-up and step-down voltage conversion is possible. The electrical device 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.
[0030] <Structure of the Electrical Device> Figure 2 is a plan view showing the electrical device 4 of this embodiment. Figure 3 is a plan view showing the electrical device 4 with the pressing member 100 removed from Figure 2. In Figure 3, the pressing member 100 is omitted from the electrical device 4 so that the arrangement of the semiconductor module 30 and the coolers 21 and 40 can be seen. The white arrows in Figure 3 indicate the direction of the refrigerant flow. Figure 4 is a cross-sectional view along the line IV-IV in Figure 2. Figure 5 is an exploded perspective view of the pressing member 100. Figure 6 is a cross-sectional view along the line VI-VI in Figure 2. Figure 7 is a plan view of the elastic member 120.
[0031] The electrical device 4 of this embodiment comprises a base 20 having a first cooler 21, a plurality of semiconductor modules 30, a second cooler 40, and a pressing member 100. The electrical device 4 may also include a capacitor 50. The electrical device 4 may also include a circuit board 60. As an example, the electrical device 4 of this embodiment comprises a base 20 having a first cooler 21, a plurality of semiconductor modules 30, a second cooler 40, a pressing member 100, a capacitor 50, and a circuit board 60. The smoothing capacitor 6 is provided by the capacitor 50. The drive circuit 7 is provided by the circuit board 60.
[0032] In the following, the direction in which the multiple semiconductor modules 30 are arranged is referred to as the X direction. The Z direction is perpendicular to the X direction and is the stacking direction of the first cooler 21, semiconductor modules 30, pressing member 100, and second cooler 40. The Y direction is perpendicular to both the X and Z directions. The Z direction corresponds to the thickness direction of the semiconductor module 30. One of these directions corresponds to the X direction. The X, Y, and Z directions are in a positional relationship that is orthogonal to each other. A plan view from the Z direction may be simply referred to as a plan view. When describing the relative positions of two members, the position of the member closer to the base 20 in the Z direction may be referred to as "down," and the position of the member further from the base 20 may be referred to as "up." First, the general configuration of each element will be described.
[0033] <Base and First Cooler> The base 20 has a semiconductor module 30 mounted on one of its surfaces 20a. The base 20 is a support member that supports the semiconductor module 30. In this embodiment, as an example, the semiconductor module 30 and the capacitor 50 are arranged on one of the surfaces 20a of the base 20. The base 20 is formed using a metal material such as aluminum.
[0034] The base 20 has a first cooler 21. The first cooler 21 is constructed using the base 20. The first cooler 21 is also made of a metal material such as aluminum. The first cooler 21 is the cooling part of the base 20. The first cooler 21 may have a flow path for a refrigerant to flow through, or it may be a heat dissipation member equipped with a heat sink or heat dissipation fins. As an example, the first cooler 21 of this embodiment is constructed with a flow path 211 formed inside the base 20 and a portion of the base 20 surrounding the flow path 211, as shown in Figures 2 to 4. A refrigerant 212 flows through the flow path 211. As the refrigerant 212, for example, a phase-changing refrigerant such as water or ammonia, or a non-phase-changing refrigerant such as ethylene glycol can be used. The first cooler 21 cools the semiconductor module 30 from the back surface 31b side.
[0035] The flow path 211 is provided so as to overlap at least a portion of each semiconductor module 30 in a plan view, in order to effectively cool the semiconductor modules 30. As an example, the flow path 211 in this embodiment is provided so as to enclose the back surface 31b of each semiconductor module 30 in a plan view. The flow path 211 extends along the direction in which the three semiconductor modules 30 are aligned, that is, along the X direction. The flow path 211 extends in the X direction.
[0036] The base 20 having the first cooler 21 may be made of a single component or of a combination of multiple components. The base 20 may be made of, for example, two components or three or more components. The base 20 may be made of a combination of multiple components in one part and a single component in the other part. The first cooler 21 may be made of a single component or of a combination of multiple components, for example by die casting. The base 20 may be a structure in which two components are combined and the first cooler 21 is locally arranged. In Figure 4, the base 20 is shown in a simplified form for convenience.
[0037] One surface 20a of the base 20 may be flat or may have irregularities. For example, in this embodiment, the capacitor mounting portion of one surface 20a is recessed relative to the semiconductor module mounting portion. The base 20 may be provided as a standalone unit or as part of a case that houses other elements of the electrical device 4. For example, the base 20 of this embodiment is provided as the bottom wall of the case 22.
[0038] The case 22 has an opening to accommodate other elements. The case 22 has a base 20 that forms the bottom wall and a side wall 23 that is connected to the base 20 and together with the base 20 defines the housing space 22S. As an example, the case 22 in this embodiment is box-shaped with one side open. The case 22 is substantially rectangular in a plan view in the Z direction. Multiple semiconductor modules 30, a second cooler 40, a pressing member 100, a capacitor 50, and a circuit board 60 are arranged in the housing space 22S of the case 22.
[0039] The side wall 23 is fitted with inlet pipes 24 for supplying refrigerant to the first cooler 21 and the second cooler 40, and outlet pipes 25 for discharging refrigerant from the first cooler 21 and the second cooler 40. The inlet pipes 24 and the outlet pipes 25 are inserted through corresponding through-holes and are positioned both inside and outside the case 22. Each of the inlet pipes 24 and the outlet pipes 25 includes a portion extending in the Y direction. The inlet pipes 24 and the outlet pipes 25 are attached, for example, to a common side wall 23.
[0040] <Semiconductor Module> The semiconductor module 30 constitutes the upper and lower arm circuit 10 described above, that is, the inverter 5. The electrical device 4 of this embodiment is equipped with three semiconductor modules 30. However, the number of semiconductor modules 30 is not limited to three. One semiconductor module 30 provides one series circuit 12, that is, one phase of the upper and lower arm circuit 10. Multiple semiconductor modules 30 include semiconductor module 30U which constitutes the upper and lower arm circuit 10U, semiconductor module 30V which constitutes the upper and lower arm circuit 10V, and semiconductor module 30W which constitutes the upper and lower arm circuit 10W.
[0041] All semiconductor modules 30 have a common structure. Each semiconductor module 30 comprises a main body 31 and an external connection terminal 32 protruding from the main body 31. The main body 31 includes a semiconductor element 33 and a encapsulant 34, etc.
[0042] The semiconductor element 33 is formed by forming a switching element on a semiconductor substrate made of silicon (Si), a wide-bandgap semiconductor with a wider bandgap than silicon, or the like. The switching element has a vertical structure so that the main current flows in the thickness direction of the semiconductor substrate. The semiconductor element 33 is sometimes referred to as a power element or semiconductor chip. The semiconductor element 33 of this embodiment includes two semiconductor elements 33H that provide the high-side switching elements of the series circuit 12, and two semiconductor elements 33L that provide the low-side switching elements of the series circuit 12.
[0043] The encapsulant 34 encapsulates some of the other elements that make up the semiconductor module 30. The remaining parts of the other elements are exposed outside the encapsulant 34. The encapsulant 34 encapsulates parts of the semiconductor element 33 and the external connection terminals 32, etc. Other parts of the external connection terminals 32 protrude outside the encapsulant 34. The encapsulant 34 is made of, for example, resin. The encapsulant 34 is molded by a transfer molding method using, for example, epoxy resin. The encapsulant 34 has, for example, a roughly rectangular shape in plan. The encapsulant 34 forms the outer casing of the main body 31.
[0044] The sealing body 34, that is, the main body 31, has, as the outer-surface forming the outline thereof, a front surface 31a and a back surface 31b which is the surface opposite to the front surface 31a in the Z direction. The front surface 31a and the back surface 31b are, for example, flat surfaces. Also, it has side surfaces 31c and 31d which are surfaces connecting the front surface 31a and the back surface 31b. The side surface 31c is the surface opposite to the side surface 31d in the Y direction. The main terminals 32P and 32N among the external connection terminals 32 project outside from the side surface 31c of the main body 31. The main terminal 32O and the signal terminal 32S among the external connection terminals 32 project outside from the side surface 31d. The main terminals 32P and 32N are connected to the bus bars 52P and 52N of the capacitor 50. The main terminal 32O is connected to a bus bar possessed by a terminal block not shown in the figure. The signal terminal 32S extends upward and is connected to a circuit board 60 provided above.
[0045] As shown in FIG. 3, the three semiconductor modules 30 are arranged side by side in the X direction. That is, the plurality of semiconductor modules 30 are arranged side by side along the X direction in a horizontal arrangement. As an example, in this embodiment, the three semiconductor modules 30 are arranged in the order of the semiconductor module 30U, the semiconductor module 30V, and the semiconductor module 30W. And, in the X direction, the side surfaces of adjacent semiconductor modules 30 face each other with a predetermined interval. Specifically, the side surface of the semiconductor module 30U and the side surface of the semiconductor module 30V face each other. The side surface of the semiconductor module 30V and the side surface of the semiconductor module 30W face each other.
[0046] <Capacitor>The capacitor 50 includes, for example, a case (not shown) and a capacitor element housed in the case. In FIGS. 2 to 4, the capacitor 50 is shown in a simplified manner. As an example, the capacitor element of the present embodiment is a film capacitor element. The capacitor element is formed by winding a film around an axis in the Z direction, for example. The capacitor element has electrodes (not shown) on both end faces in the Z direction. The electrodes are sometimes referred to as metallization. The capacitor 50 includes a P terminal connected to the electrode on the positive electrode side and an N terminal connected to the electrode on the negative electrode side. The capacitor 50 further includes a P bus bar 52P and an N bus bar 52N. The P bus bar 52P electrically connects the main terminal 32P of the semiconductor module 30 and the P terminal of the capacitor 50. The N bus bar 52N electrically connects the main terminal 32N of the semiconductor module 30 and the N terminal of the capacitor 50. The capacitor 50 is provided so as to be adjacent to the semiconductor module 30 in a plan view.
[0047] <Second Cooler>The second cooler 40 is provided without diverting the base 20. The second cooler 40 is disposed on one surface 31a of the semiconductor module 30. The second cooler 40 is stacked and disposed on the main body 31 of the semiconductor module 30 on the opposite side to the first cooler 21. The second cooler 40 cools the semiconductor module 30 from the opposite side to the first cooler 21 in the Z direction. The second cooler 40 and the first cooler 21 can cool the semiconductor module 30 from both sides in the Z direction.
[0048] The second cooler 40 has a flow path 41 inside. As an example, in the flow path 41 of the present embodiment, the refrigerant 42 is supplied through the introduction pipe 24. The refrigerant 42 that has flowed through the flow path 41 is discharged outside the electric device 4 through the discharge pipe 25. The second cooler 40 is disposed in the accommodation space 22S of the case 22. The refrigerant 42 is common to the above-described refrigerant 212.
[0049] As an example, the second cooler 40 in this embodiment is thinner than the first cooler 21. The second cooler 40 is, for example, a tubular body with an overall flattened shape. The second cooler 40 is configured to have a flow path 41 inside using, for example, a pair of plates (thin metal plates). At least one of the pair of plates is processed into a shape that bulges in the Z direction by press working. Then, the outer edges of the pair of plates are fixed together by crimping or the like, and joined together all around by brazing or the like. This forms a flow path 41 through which refrigerant 42 can flow between the pair of plates. The second cooler 40 is made of aluminum.
[0050] The flow path 41 is provided so as to effectively cool the semiconductor modules 30, overlapping at least a portion of each semiconductor module 30 in a plan view. In this embodiment, the flow path 41 is provided so as to overlap one surface 31a of each semiconductor module 30 in a plan view. The flow path 41 extends along the direction in which the three semiconductor modules 30 are aligned, i.e., the X direction. The flow path 41 extends in the X direction. The flow path 41 crosses the three semiconductor modules 30 in the X direction. For example, in a plan view, the flow path 41 is contained within the flow path 211. The extended length of the flow path 41 is shorter than the extended length of the flow path 211. The extended length of the flow path 41 may be equal to or longer than the extended length of the flow path 211.
[0051] The second cooler 40 is connected to the first cooler 21 via connecting pipes 45 and 46. Connecting pipe 45 is connected to the vicinity of one end of the second cooler 40 in the X direction, specifically the end closer to the inlet pipe 24. Connecting pipe 46 is connected to the vicinity of the other end of the second cooler 40, specifically the end closer to the outlet pipe 25. The two connecting pipes 45 and 46 are positioned in the X direction between the connection point between the inlet pipe 24 and the first cooler 21 and the connection point between the outlet pipe 25 and the first cooler 21.
[0052] A portion of the refrigerant supplied from the inlet pipe 24 flows through the flow path 211 as refrigerant 212 and is discharged from the discharge pipe 25. Another portion of the refrigerant is supplied to the flow path 41 through the flow path of the flow path 211 and the flow path of the connecting pipe 45. The refrigerant 42 that has flowed through the flow path 41 flows back into the flow path 211 through the flow path of the connecting pipe 46 and is discharged from the discharge pipe 25. The flow rate of refrigerant 212 flowing through the flow path 211 is greater than the flow rate of refrigerant 42 flowing through the flow path 41. The flow path 211 is the main flow path, and the flow path 41 is a secondary flow path branched off from the flow path 211.
[0053] <Thermal Conducting Member> The electrical device 4 also has a thermal conducting member 70 that transmits heat from the semiconductor module 30 to the coolers 21 and 40. The thermal conducting member 70 has electrical insulating properties. As an example, the thermal conducting member 70 in this embodiment is thermal conductive grease. A thermal conductive gel may be used instead of thermal conductive grease. The thermal conducting member 70 is sometimes referred to as TIM. TIM is an abbreviation for Thermal Interface Material. The thermal conducting member 70 is flexible under the operating environment. The thermal conducting member 70 is flexible at least during manufacturing.
[0054] Because the heat conduction member 70 is flexible, it absorbs thickness errors of the multiple semiconductor modules 30. The heat conduction member 70 enhances the adhesion between the semiconductor modules 30 and the coolers 21 and 40. The heat conduction member that transfers the heat of the semiconductor modules 30 to the first cooler 21 is sometimes referred to as the first heat conduction member 71. The heat conduction member 70 that transfers the heat of the semiconductor modules 30 to the second cooler 40 is sometimes referred to as the second heat conduction member 72. The first heat conduction member 71 is provided between the semiconductor modules 30 and the first cooler 21, and the semiconductor modules 30 and the first cooler 21 are in close contact via the first heat conduction member 71. The second heat conduction member 72 is provided between the semiconductor modules 30 and the second cooler 40, and the semiconductor modules 30 and the second cooler 40 are in close contact via the second heat conduction member 72.
[0055] <Pressing Member> The pressing member 100 is positioned on the back surface 31b of the multiple semiconductor modules 30. The pressing member 100 overlaps the multiple semiconductor modules 30 with respect to the Z direction. The pressing member 100 is formed of a material with higher rigidity than the first cooler 21. For example, the pressing member 100 is made of steel plate or stainless steel. The pressing member 100 has a fixing plate 110, an elastic member 120, a back plate 130, and a fixing member 140. The elastic member 120 is provided between the fixing plate 110 and the back plate 130. The fixing plate 110 and the back plate 130 are fixed together via a fixing member 140 called a rivet. Note that the fixing member 140 is not limited to a rivet. Also, the rigidity of the fixing plate 110, the elastic member 120, and the back plate 130 are almost the same. Here, rigidity refers to mechanical rigidity.
[0056] The components of the pressing member 100 are stacked in the order of back plate 130, elastic member 120, and fixing plate 110 from bottom to top. The elastic member 120 is a metal grid spring. For example, the elastic member 120 is made of stainless steel. A grid spring is a planar spring in which multiple small leaf springs are arranged. In this embodiment, the elastic member 120 has a frame 121, a plurality of connecting parts 123, and a plurality of pressing pieces 125.
[0057] The frame 121 has four sides 122 surrounding the opening. The frame 121 is roughly rectangular in plan view. The frame 121 has two sides 122a and 122c aligned in the X direction and two sides 122b and 122d aligned in the Y direction. Holes 126 are provided in the two sides 122a and 122c aligned in the X direction through which the fixing member 140 passes. Similarly, the main part 111 of the fixing plate 110 also has holes 116 through which the fixing member 140 passes. The fixing member 140 is passed through the two holes 116 and 126 and crimped, thereby fixing the fixing plate 110 and the elastic member 120. As will be explained in more detail later, the fixing plate 110 is fixed to the boss 26 at a predetermined distance from the base 20 in the Z direction.
[0058] Multiple connecting parts 123 are provided to connect two sides 122b and 122d aligned in the Y direction. In this embodiment, five connecting parts 123 are provided to connect two sides 122b and 122d. The five connecting parts 123 are provided at predetermined distances apart in the X direction. As an example, the connecting parts 123 extend along the Y direction. The connecting parts 123 have an end 124a on the side 122a and an end 124c on the side 122c. A pressing piece 125 is provided at each of the ends 124a and 124c.
[0059] The pressing piece 125 is made of the same material as the connecting portion 123 and is integrated with it. The pressing piece 125 is cantilevered to the connecting portion 123. The pressing piece 125 has a trapezoidal shape, becoming narrower as it moves away from the connecting portion 123. The pressing piece 125 is cantilevered to the connecting portion 123 and extends diagonally toward the back plate 130. When the fixing plate 110 is fixed to the boss 26, the pressing piece 125 is elastically deformed so as to be compressed in the Z direction.
[0060] The connecting portion 123 has a first connecting portion 123a and a second connecting portion 123b. The connecting portion 123 has three first connecting portions 123a and two second connecting portions 123b. The first connecting portions 123a and second connecting portions 123b are arranged alternately from edge 122a toward edge 122c. A first connecting portion 123a is provided next to edge 122a. A first connecting portion 123a is provided next to edge 122c.
[0061] Two pressing pieces 125 are provided at each end 124a and 124c of the first connecting portion 123a. The two pressing pieces 125 provided at the ends 124a and 124c are arranged at a predetermined distance apart in the Y direction. In addition, one pressing piece 125 is provided at each end 124a and 124c of the second connecting portion 123b. For the sake of simplicity in the following explanation, the pressing piece 125 provided at the first connecting portion 123a may be referred to as the first pressing piece 125a, and the pressing piece 125b provided at the second connecting portion 123b may be referred to as the second pressing piece 125b.
[0062] A second pressing piece 125b is provided on end 124a between two first pressing pieces 125a provided on end 124c. A second pressing piece 125b is provided on end 124c between two first pressing pieces 125a provided on end 124a. At all locations, the distance in the Y direction between the second pressing piece 125b and the first pressing pieces 125a provided on both sides is set to be equal.
[0063] The pressing pieces 125 provided on two adjacent connecting portions 123a and 123b are arranged so that their tips do not overlap in the X direction. The pressing pieces 125 provided on two adjacent connecting portions 123a and 123b partially overlap in the Y direction. In a plan view, the first pressing piece 125a and the second pressing piece 125b are arranged in a grid pattern so that they are staggered. Multiple pressing pieces 125 are provided so as to overlap the back plate 130 in the Z direction. Multiple pressing pieces 125 are in contact with the back plate 130. The back plate 130 is pressed against the second cooler 40 by the reaction force from the pressing pieces 125. In this embodiment, as an example, all pressing pieces 125 are provided so as to contact the back plate 130. Note that each pressing piece 125 only needs to have the ability to improve the adhesion between at least one semiconductor module 30 and the second cooler 40, and may have a relatively small spring constant.
[0064] Furthermore, a gap 127 is provided between two first pressing pieces 125a located at the ends 124a and 124c of the first connecting portion 123a adjacent to sides 122a and 122c. A nut 150 for fixing a stay 61 for positioning the circuit board 60 is passed through this gap 127. In addition to the components described above, the electrical device 4 further includes a stay 61 and a nut 150. The stay 61 and the nut 150 are housed in a housing space 22S. The semiconductor module 30, second cooler 40, pressing member 100, stay 61, and circuit board 60 are stacked in that order from bottom to top.
[0065] The nut 150 has a head 151 and a shaft 152. The fixing plate 110 and the back plate 130 are provided with holes 117 and 137 for passing the shaft 152 through. The holes 117 and 137 are positioned to overlap with the gap 127 in the Z direction, and the holes 117, 137 and the gap 127 are in communication in the Z direction. The head 151 is located above the fixing plate 110. The shaft 152 passes through the holes 117, 137 and the gap 127.
[0066] A stay 61 passes through the shaft portion 152, and a circuit board 60 is fixed above the stay 61. On the other hand, the end of the shaft portion 152 opposite to the circuit board 60 is in contact with the second cooler 40. The shaft portion 152 is provided in a columnar shape between the circuit board 60 and the second cooler 40. In this way, in the elastic member 120 of this embodiment, the arrangement of the pressing piece 125 makes it easier for the reaction force to act uniformly on the back plate 130, and the internal structure of the housing space 22S can be made compact in the planar direction.
[0067] The fixing plate 110 is made of steel plate. The fixing plate 110 has a main portion 111 and a flange 112. The main portion 111 is flattened in the Z direction. The main portion 111 is roughly rectangular in plan view. The main portion 111 has an upper surface 111a on the circuit board 60 side and a lower surface 111b on the elastic member 120 side. As described above, the elastic member 120 is fixed to the main portion 111 via a fixing member 140. The lower surface 111b overlaps the elastic member 120. The lower surface 111b is in contact with the elastic member 120. In plan view, the main portion 111 encloses the elastic member 120.
[0068] Furthermore, a portion of the main part 111 overlaps with the base 20 in the Z direction. A boss 26 is provided on the base 20 at the overlapping portion with the main part 111, projecting toward the main part 111. The main part 111 is provided with a hole 118 at the location corresponding to the boss 26, through which the shaft portion 81 of the bolt 80 can pass. The shaft portion 81 of the bolt 80 is passed through the hole 118 and the boss 26, and the shaft portion 81 is fixed to the boss 26, thereby defining the position of the fixing plate 110 in the Z direction. The fixing plate 110 is fixed to the boss 26 at a predetermined distance from the base 20 in the Z direction. The bolt 80 is one of the components of the electrical device 4.
[0069] The fixing plate 110 has a flange 112 extending downward at the Y-direction end 111c of the main portion 111. The flange 112 extends in the Z-direction toward the first cooler 21. The flange 112 serves as a reinforcing part that suppresses deformation of the main portion 111 in the Z-direction. The fixing plate 110 has a substantially U-shape in the YZ plane. The flange 112 overlaps the elastic member 120 with respect to the Y-direction.
[0070] The back plate 130 is made of steel plate. The back plate 130 has a flattened shape in the Z direction. In plan view, the back plate 130 is approximately rectangular. The back plate 130 has an upper surface 131a on the elastic member 120 side and a lower surface 131b on the second cooler 40 side. The upper surface 131a overlaps the elastic member 120. The upper surface 131a is in contact with the elastic member 120. The lower surface 131b overlaps the second cooler 40. In plan view, the back plate 130 encloses the second cooler 40. The lower surface 131b is in contact with the second cooler 40.
[0071] In this configuration, the elastic member 120 is provided between the fixed plate 110 and the back plate 130. With this arrangement, the elastic member 120 elastically deforms between the fixed plate 110 and the back plate 130. Specifically, the pressing piece 125 elastically deforms. When it elastically deforms, the contact area between the pressing piece 125 and the back plate 130 increases, and a reaction force is generated from the pressing piece 125. Due to the reaction force from the elastic deformation of the pressing piece 125, the back plate 130 is pressed against the second cooler 40. The second cooler 40 is pressed against the semiconductor module 30 via the second heat conductive member 72.
[0072] <Second Cooler and Pressing Member> As described above, the flow rate of the refrigerant 42 flowing through the second cooler 40 is smaller than the flow rate of the refrigerant 212 flowing through the first cooler 21. Therefore, the temperature of the second cooler 40 does not decrease as easily as that of the first cooler 21, and it has a higher thermal resistance than the first cooler 21. The thermal rigidity of the second cooler 40 is lower than that of the first cooler 21. Thermal rigidity refers to the force with which a material resists deformation due to heat. In other words, the thermal deformation of the second cooler 40 is greater than the thermal deformation of the first cooler 21. The second cooler 40 is more easily deformed by heat than the first cooler 21.
[0073] The second cooler 40 is provided between the pressing member 100 and the semiconductor module 30 in the Z direction. As described above, the pressing member 100 is made of steel plate or stainless steel, and the second cooler 40 is made of aluminum. The mechanical rigidity of the pressing member 100 is greater than that of the second cooler 40. Therefore, even if the second cooler 40 tries to deform due to heat, it is easily pressed down by the pressing member 100. This suppresses deformation of the second cooler 40. It also suppresses the second cooler 40 from separating from the semiconductor module 30.
[0074] In this embodiment, the second cooler 40, which has low thermal rigidity and is easily deformed by heat, is pressed by the pressing member 100, which has high mechanical rigidity, thereby suppressing a decrease in the contact area between the second cooler 40 and the semiconductor module 30. In addition to the thermal deformation described above, deformation due to the internal pressure of the refrigerant 42 flowing through the flow path 41 may also be included as a factor in the deformation of the second cooler 40. Furthermore, the pressing piece 125 receives the deformation of the second cooler 40 due to thermal deformation and the internal pressure of the flow path 41, thereby suppressing a decrease in the axial force of the fixing plate 110.
[0075] <Effects> The electrical device 4 includes a plurality of semiconductor modules 30, a first cooler 21, a second cooler 40, and a pressing member 100. The first cooler 21 cools the semiconductor modules 30 from the back surface 31b. The second cooler 40 cools the semiconductor modules 30 from one surface 31a. The pressing member 100 overlaps the second cooler 40 and presses the second cooler 40 against the plurality of semiconductor modules 30. The pressing member 100 includes a fixing plate 110, an elastic member 120, and a back plate 130. The back plate 130 overlaps the second cooler 40. The fixing plate 110 is fixed via the back plate 130 at a position away from the second cooler 40 in the Z direction. The elastic member 120 is sandwiched between the back plate 130 and the fixing plate 110. The elastic member 120 undergoes elastic deformation when sandwiched, and the reaction force from this elastic deformation presses the back plate 130 against the second cooler 40.
[0076] The backplate 130 prevents the elastic member 120 from directly contacting the second cooler 40. This prevents the reaction force of the elastic member 120 from acting locally on the second cooler 40. The reaction force of the elastic member 120 is more likely to act uniformly on the second cooler 40. Consequently, pressure is more likely to be applied uniformly from the second cooler 40 to the multiple semiconductor modules 30. This prevents unevenness in the contact state between the multiple semiconductor modules 30 and the second cooler 40 depending on the location. This prevents significant differences in thermal conductivity between the multiple semiconductor modules 30 and the second cooler 40 depending on the location. This improves the heat dissipation efficiency of the multiple semiconductor modules 30.
[0077] In this embodiment, the second cooler 40 is simultaneously pressed against multiple semiconductor modules 30 via a single backplate 130 by the reaction force of the elastic member 120. When pressing the second cooler 40 against multiple semiconductor modules 30, unlike in this embodiment, it is conceivable that multiple elastic members 120 and backplates 130 corresponding to each semiconductor module 30 are provided. However, in that case, one set of elastic member 120 and backplate 130 is required for each semiconductor module 30. This increases the number of parts compared to this embodiment. In this embodiment, the second cooler 40 can be pressed against multiple semiconductor modules 30 with one elastic member 120 and one backplate 130. Therefore, the number of parts can be reduced.
[0078] The electrical device 4 has a second heat conductive member 72 between the second cooler 40 and the semiconductor module 30. The second heat conductive member 72 is flexible, and the semiconductor module 30 and the second cooler 40 are in close contact via the second heat conductive member 72. In this embodiment, the second cooler 40 cools multiple semiconductor modules 30 simultaneously. Due to manufacturing tolerances, the dimensions of the main body 31 in the Z direction may differ among the multiple semiconductor modules 30. However, in this embodiment, as described above, a flexible second heat conductive member 72 is provided between the second cooler 40 and the semiconductor module 30. This allows the second heat conductive member 72 to absorb the dimensional errors in the Z direction even if there are dimensional errors in the Z direction among the multiple semiconductor modules 30, thereby improving the contact between the semiconductor module 30 and the second cooler 40.
[0079] The fixing plate 110 has a main portion 111 and a flange 112. The main portion 111 fixes the elastic member 120 and overlaps the back plate 130 in the Z direction. The flange 112 is provided at the end 111c of the main portion 111. The flange 112 extends in the Z direction toward the back plate 130. The flange 112 acts as a reinforcing portion that suppresses deformation of the main portion 111 in the Z direction. This improves the mechanical rigidity of the main portion 111 and suppresses deformation of the main portion 111 toward the back plate 130. Since the elastic member 120 is fixed to the main portion 111, suppressing the deformation of the main portion 111 suppresses the movement of the elastic member 120 toward the back plate 130. This prevents a decrease in the contact area between the elastic member 120 and the back plate 130.
[0080] The elastic member 120 has a frame 121, a plurality of connecting parts 123, and a plurality of pressing pieces 125. The frame 121 has four sides 122a, 122b, 122c, and 122d that surround the opening. A plurality of connecting parts 123 are provided to connect the insides of two sides 122b and 122d. The pressing pieces 125 are made of the same material as the connecting parts 123 and are integrally formed. The pressing pieces 125 are cantilevered to the connecting parts 123, extend diagonally toward the back plate 130, and are compressed in the Z direction. The back plate 130 is pressed against the second cooler 40 by the reaction force due to the elastic deformation of the pressing pieces 125. A plurality of pressing pieces 125 are provided so as to overlap the back plate 130, and the back plate 130 is pressed against the second cooler 40 by the reaction force from the plurality of pressing pieces 125. According to this, the reaction force of the elastic member 120 is more easily applied uniformly to the second cooler 40.
[0081] Multiple connecting portions 123 are provided at predetermined distances apart in the X direction. Two pressing pieces 125 are provided at each end 124a and 124c of the first connecting portion 123a. One pressing piece 125 is provided at each end 124a and 124c of the second connecting portion 123b. The pressing pieces 125 provided at two adjacent connecting portions 123a and 123b partially overlap in the Y direction. Furthermore, in a plan view, the first pressing piece 125a and the second pressing piece 125b are arranged in a grid pattern so that they are staggered. This allows more pressing pieces 125 to be provided at the connecting portion 123 without increasing the size of the pressing member 100 in the X direction.
[0082] (Second Embodiment) In the first embodiment, a configuration was described in which the components of the first cooler 21 and the second cooler 40 are the same. However, the components of the first cooler 21 and the second cooler 40 do not have to be the same. The components of each may be selected such that the mechanical rigidity of the second cooler 40 is higher than that of the first cooler 21. For example, the first cooler 21 may be made of aluminum and the second cooler 40 may be made of steel or stainless steel.
[0083] In this case, the thermal rigidity of the second cooler 40 is higher than that of the first cooler 21. In other words, the thermal deformation of the second cooler 40 is smaller than that of the first cooler 21. The second cooler 40 is less susceptible to deformation due to heat than the first cooler 21. This prevents the second cooler 40 from separating from the semiconductor module 30. In the second embodiment as well, the heat dissipation efficiency of the semiconductor module 30 can be improved.
[0084] (Third Embodiment) The vehicle drive system 1 is not limited to the configuration described above. For example, although an example with one motor generator 3 has been shown, it is not limited to this. Multiple motor generators may be provided. Also, although an example with an inverter 5 as a power conversion circuit has been shown for the electrical device 4, it is not limited to this. For example, a configuration with multiple inverters may be used. A configuration with at least one inverter and a converter may also be used.
[0085] (Other Embodiments) The disclosures in this specification and drawings are not limited to the exemplary embodiments. The disclosures include the exemplary embodiments and variations thereof by those skilled in the art. For example, the disclosures are not limited to combinations of parts and / or elements shown in the embodiments. The disclosures are implementable in a variety of combinations. The disclosures may have additional parts that can be added to the embodiments. The disclosures include those in which parts and / or elements of the embodiments have been omitted. The disclosures include substitutions or combinations of parts and / or elements between one embodiment and another. The scope of the disclosed technical areas is not limited to the descriptions of the embodiments. Some of the scope of the disclosed technical areas are indicated by the descriptions of the claims and should be understood to include modifications within the scope equivalent to the descriptions of the claims.
[0086] 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.
[0087] (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.
[0088] (Technical Concept 1) An electrical device comprising: a plurality of semiconductor modules (30) having one surface (31a) and a back surface (31b) spaced apart in the thickness direction (Z), and arranged in one direction (X) perpendicular to the thickness direction; a first cooler (21) for cooling the plurality of semiconductor modules from the back surface side; a second cooler (40) for cooling the plurality of semiconductor modules from the one surface side; and a pressing member (100) that overlaps the second cooler in the thickness direction and presses the second cooler against the plurality of semiconductor modules, wherein the pressing member comprises: a back plate (130) that overlaps the second cooler; a fixing plate (110) provided on the opposite side from the second cooler via the back plate and fixed at a predetermined distance from the back plate in the thickness direction; and an elastic member (120) sandwiched between the back plate and the fixing plate and pressing the back plate against the second cooler by a reaction force due to deformation.
[0089] (Technical Concept 2) The electrical device according to Technical Concept 1, wherein the second cooler has lower thermal rigidity than the first cooler, and the pressing member has higher mechanical rigidity than the second cooler.
[0090] (Technical Concept 3) An electrical device according to technical concept 1 or 2, comprising a flexible heat conductive member (72) between the second cooler and the semiconductor module.
[0091] (Technical Idea 4) The fixing plate has a main portion (111) that fixes the elastic member and overlaps the back plate in the thickness direction, and a reinforcing portion (112) that extends from the main portion toward the back plate in the thickness direction and suppresses deformation of the main portion, as described in any one of Technical Ideas 1 to 3.
[0092] (Technical Idea 5) The electrical device according to any one of Technical Ideas 1 to 4, wherein the elastic member comprises a frame (121) that opens in the plate thickness direction, a plurality of connecting parts (123) provided inside the frame and connecting the sides of the frame, and a plurality of pressing pieces (125) that are cantilevered to each of the connecting parts and press the back plate against the second cooler, and the plurality of pressing pieces overlap the back plate with respect to the plate thickness direction.
[0093] (Technical Concept 6) An electrical device according to Technical Concept 5, wherein a plurality of the connecting parts are spaced apart in one direction, and a plurality of the pressing pieces, supported by two adjacent connecting parts, overlap in a direction different from the one direction.
[0094] (Technical idea 7) The electrical device according to technical idea 6, wherein the plurality of pressing pieces are arranged in a grid pattern so as to be alternating when viewed from the plate thickness direction.
[0095] (Technical Idea 8) An electrical device according to any one of Technical Ideas 1 to 7, wherein the mechanical rigidity of the second cooler is higher than that of the first cooler.
Claims
1. An electrical device comprising: a plurality of semiconductor modules (30) having one surface (31a) and a back surface (31b) spaced apart in the thickness direction (Z), and arranged in one direction (X) perpendicular to the thickness direction; a first cooler (21) for cooling the plurality of semiconductor modules from the back surface side; a second cooler (40) for cooling the plurality of semiconductor modules from the one surface side; and a pressing member (100) that overlaps the second cooler in the thickness direction and presses the second cooler against the plurality of semiconductor modules, wherein the pressing member comprises: a back plate (130) that overlaps the second cooler; a fixing plate (110) provided on the opposite side from the second cooler via the back plate and fixed at a predetermined distance from the back plate in the thickness direction; and an elastic member (120) sandwiched between the back plate and the fixing plate and pressing the back plate against the second cooler by a reaction force due to deformation.
2. The electrical device according to claim 1, wherein the second cooler has lower thermal rigidity than the first cooler, and the pressing member has higher mechanical rigidity than the second cooler.
3. The electrical device according to claim 1 or 2, further comprising a flexible heat conductive member (72) between the second cooler and the semiconductor module.
4. The electrical device according to claim 3, wherein the fixing plate has a main portion (111) that fixes the elastic member and overlaps the back plate in the thickness direction, and a reinforcing portion (112) that extends from the main portion toward the back plate in the thickness direction and suppresses deformation of the main portion.
5. The electrical device according to claim 4, wherein the elastic member comprises a frame (121) opening in the plate thickness direction, a plurality of connecting parts (123) provided inside the frame and connecting the sides of the frame, and a plurality of pressing pieces (125) cantilevered to each of the connecting parts and pressing the back plate against the second cooler, the plurality of pressing pieces overlapping the back plate with respect to the plate thickness direction.
6. The electrical device according to claim 5, wherein a plurality of the connecting portions are spaced apart in one direction, and a plurality of the pressing pieces, supported by two adjacent connecting portions, overlap in a direction different from the one direction.
7. The electrical device according to claim 6, wherein the plurality of pressing pieces are arranged in a grid pattern so as to be alternating when viewed from the plate thickness direction.
8. The electrical device according to claim 1 or 2, wherein the mechanical rigidity of the second cooler is higher than that of the first cooler.