Power conversion device

Abstract

To provide a power conversion device in which deterioration of the heat radiability can be suppressed.SOLUTION: A power conversion device 4 includes a semiconductor module 20 constituting an inverter 5, coolers 30, 40 that cool the semiconductor module 20 from both surface sides, and connection pipes 50, 60 that connect the coolers 30, 40. The cooler 30 includes a case 31 that defines a flow channel 32 and has an opening portion 311 in a portion overlapping the semiconductor module 20, a base plate 331 disposed in the case 31 so as to close the opening portion 311, and a pin fin 332 that extends from the base plate 331 into the flow channel 32. In a direction in which the connection pipes 50, 60 are arranged, the length of the base plate 331 is shorter than the distance between outer ends of the connection pipes 50, 60.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The disclosure herein relates to power conversion devices. [Background technology]

[0002] Patent Document 1 discloses a power conversion device. The contents of the prior art documents are incorporated by reference as explanations of technical elements in this specification. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] China Patent Application Publication No. 114068450 Summary of the Invention [Problem to be solved by the invention]

[0004] The power converter disclosed in Patent Document 1 includes a two-stage cooler. The power converter has a structure that dissipates heat from the chips that constitute the inverter to both sides. The case of the cooler is provided with fins for dissipating heat. In the configuration of Patent Document 1, the case may bend outward, that is, deformed, due to water pressure. When the case bends outward, the gap between the fins and the case becomes larger, and the amount of refrigerant that passes through without hitting the fins increases, decreasing the heat dissipation performance. When the case deforms, the adhesion between the case and the chip decreases, and the thermal resistance increases. Thus, the configuration of Patent Document 1 may decrease the heat dissipation performance. In the above-mentioned viewpoints, or in other viewpoints not mentioned, further improvements are required for the power converter.

[0005] One disclosed object is to provide a power conversion device capable of suppressing a decrease in heat dissipation performance. [Means for solving the problem]

[0006] The power conversion device disclosed herein is A semiconductor module (20) constituting a power conversion circuit (5); a first cooler (30) having a first flow path (32) and configured to cool a semiconductor module; a second cooler (40) having a second flow path (42) and cooling the semiconductor module from the opposite side to the first cooler; a first connecting portion (50) having a first connecting flow path (51) communicating with the first flow path and the second flow path; a second connecting portion (60) having a second connecting flow path (61) communicating with the first flow path and the second flow path and providing, together with the first connecting portion, a bypass path for a part of the refrigerant; Equipped with The first cooler includes a case (31) that defines a first flow path and has an opening at a portion that overlaps with the semiconductor module, a base plate (331) that is disposed on the case so as to cover the opening, and pin fins (332) that extend from the base plate into the first flow path; In the arrangement direction of the first connecting portion and the second connecting portion, the length of the base plate is shorter than the length between the outer ends of the first connecting portion and the second connecting portion.

[0007] According to the disclosed power converter, since the length of the base plate is shorter than the length between the outer ends of the first and second connecting parts, deformation of the base plate due to water pressure can be suppressed, and as a result, a power converter capable of suppressing deterioration of heat dissipation can be provided.

[0008] The various aspects disclosed in this specification adopt different technical means to achieve their respective objectives. The claims and the parenthetical symbols described in this section are merely illustrative of the corresponding relationship with the embodiments described below, and are not intended to limit the technical scope. The objectives, features, and effects disclosed in this specification will become clearer with reference to the following detailed description and the accompanying drawings. [Brief description of the drawings]

[0009] [Figure 1] 1 is a diagram showing a circuit configuration and a drive system of a power conversion device according to a first embodiment. [Diagram 2] FIG. 2 is a plan view showing the power conversion device. [Diagram 3] FIG. 3 is a cross-sectional view taken along line III-III in FIG. [Figure 4] FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. [Diagram 5] FIG. [Figure 6] FIG. [Figure 7] FIG. 11 is a plan view showing a power conversion device according to a second embodiment. [Figure 8] FIG. 8 is a cross-sectional view taken along line VIII-VIII in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, several embodiments will be described with reference to the drawings. In addition, by assigning the same reference numerals to corresponding components in each embodiment, duplicated explanations may be omitted. When only a part of the configuration is described in each embodiment, the configuration of the other embodiment described above can be applied to the other parts of the configuration. In addition to the combination of configurations explicitly stated in the description of each embodiment, configurations of several embodiments can be partially combined together even if not explicitly stated, as long as there is no particular problem with the combination.

[0011] The power conversion device of this embodiment is applied to, for example, a moving body using a rotating electric machine as a drive source. The moving body is, for example, an electric vehicle such as a battery electric vehicle (BEV), a hybrid electric vehicle (HEV), or a plug-in hybrid electric vehicle (PHEV), an electric flying object such as a drone or an electric vertical take-off and landing aircraft (eVTOL), a ship, a construction machine, or an agricultural machine. An example of application to a vehicle will be described below.

[0012] (First embodiment) First, a schematic configuration of a drive system of a vehicle will be described with reference to FIG.

[0013] <Vehicle drive system> As shown in FIG. 1, a vehicle drive system 1 includes a DC power supply 2, a motor generator 3, and a power conversion device 4.

[0014] The DC power supply 2 is a DC voltage source composed of a chargeable and dischargeable secondary battery. The secondary battery is, for example, a lithium ion battery, a nickel metal hydride battery, an organic radical battery, or the like. The motor generator 3 is a three-phase AC rotating electric machine. The motor generator 3 functions as a drive source for the vehicle, that is, an electric motor. The motor generator 3 functions as a generator during regeneration. The power conversion device 4 performs power conversion between the DC power supply 2 and the motor generator 3.

[0015] <Circuit configuration of power conversion device> 1 shows a circuit configuration of a power conversion device 4. The power conversion device 4 includes at least a power conversion circuit. The power conversion circuit in this embodiment is an inverter 5. The power conversion device 4 may further include a smoothing capacitor 6, a drive circuit 7, and the like.

[0016] The smoothing capacitor 6 mainly smoothes the DC voltage supplied from the DC power supply 2. The smoothing capacitor 6 is connected to a P line 8 which is a power supply line on the high potential side and an N line 9 which is a power supply line on the low potential side. The P line 8 is connected to the positive electrode of the DC power supply 2, and the N line 9 is connected to the negative electrode of the DC power supply 2. The positive electrode of the smoothing capacitor 6 is connected to the P line 8 between the DC power supply 2 and the inverter 5. The negative electrode 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.

[0017] The inverter 5 is a DC-AC conversion circuit. The inverter 5 converts a DC voltage into a three-phase AC voltage in accordance with switching control by a control circuit (not shown) and outputs the voltage 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 upon receiving rotational force from the wheels into a DC voltage in accordance with switching control by the control circuit and outputs the DC voltage to the P line 8. In this way, the inverter 5 performs bidirectional power conversion between the DC power source 2 and the motor generator 3.

[0018] The inverter 5 is configured to include upper and lower arm circuits 10 for three phases. 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.

[0019] A connection point between the upper arm 10H and the lower arm 10L, i.e., a midpoint of the upper and lower arm circuits 10, is connected to a corresponding phase winding 3a of the motor generator 3 via an output line 11. Of the upper and lower arm circuits 10, a U-phase upper and lower arm circuit 10U is connected to the U-phase winding 3a via an output line 11. A V-phase upper and lower arm circuit 10V is connected to the V-phase winding 3a via an output line 11. A W-phase upper and lower arm circuit 10W is connected to the W-phase winding 3a via an output line 11.

[0020] The upper and lower arm circuits 10 (10U, 10V, 10W) ​​have a series circuit 12. The upper and lower arm circuits 10 may have one or more series circuits 12. When there are more than one series circuits 12, the series circuits 12 are connected in parallel to each other to configure 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 a switching element on the upper arm 10H side and a switching element on the lower arm 10L side in series between the P line 8 and the N line 9.

[0021] The number of high-side switching elements and low-side switching elements constituting the series circuit 12 is not particularly limited. It may be one or more. The series circuit 12 of this embodiment has two switching elements on the high-side side and two switching elements on the low-side side. Two switching elements on the high-side side are connected in parallel, and two switching elements on the low-side side are connected in parallel to constitute one series circuit 12. In other words, each of the six arms 10H, 10L of the upper and lower arm circuits 10 for three phases is constituted by two switching elements connected in parallel to each other.

[0022] In this embodiment, an n-channel MOSFET 13 is 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).

[0023] A free wheel diode 14 (hereinafter referred to as FWD 14) is connected in anti-parallel to each of the MOSFETs 13. In the case of the MOSFETs 13, the FWD 14 may be a parasitic diode (body diode) or an external diode. In the upper arm 10H, the drain of the MOSFET 13 is connected to a P line 8. In the lower arm 10L, the source of the MOSFET 13 is connected to an N line 9. The source of the MOSFET 13 in the upper arm 10H and the drain of the MOSFET 13 in the lower arm 10L are connected to each other. The anode of the FWD 14 is connected to the source of the corresponding MOSFET 13, and the cathode is connected to the drain.

[0024] The switching element is not limited to the 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 inverse parallel.

[0025] The drive circuit 7 drives switching elements constituting a power conversion circuit such as the inverter 5. The drive circuit 7 supplies a drive voltage to the gate of the corresponding MOSFET 13 based on a drive command from the control circuit. The drive circuit drives the corresponding MOSFET 13, i.e., turns it on and off, by applying the drive voltage. The drive circuit is sometimes referred to as a driver.

[0026] The power conversion 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 host ECU (not shown) and signals detected by various sensors. ECU is an abbreviation for Electronic Control Unit. The control circuit may be provided in the host ECU.

[0027] The various sensors include, for example, a current sensor, a rotation angle sensor, and a voltage sensor. The power conversion device 4 may include at least one of the sensors. The current sensor detects the phase current flowing through the winding 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 a memory. The control circuit outputs, for example, a PWM signal as a drive command. PWM is an abbreviation for Pulse Width Modulation.

[0028] The power conversion device 4 may include a converter as a power conversion circuit. The converter is a DC-DC conversion circuit that converts a DC voltage, for example, into a DC voltage of a different value. The converter is provided between the DC power source 2 and the smoothing capacitor 6. The converter is configured to include, for example, a reactor and the above-mentioned upper and lower arm circuits 10. With this configuration, voltage can be increased and decreased. The power conversion device 4 may include a filter capacitor that removes power supply noise from the DC power source 2. The filter capacitor is provided between the DC power source 2 and the converter.

[0029] <Structure of power conversion device> FIG. 2 is a plan view showing an example of the power conversion device 4 according to the present embodiment. For convenience, signal terminals and a circuit board are omitted in FIG. 2. The white arrows in FIG. 2 indicate the direction in which the refrigerant flows. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2. FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 3. In FIG. 4, a part of the housing and the circuit board are omitted. In FIG. 4, the solid arrows in FIG. 4 indicate the flow of the refrigerant. FIG. 5 is a plan view showing a heat dissipation member. The white arrows in FIG. 5 also indicate the direction in which the refrigerant flows.

[0030] The power converter 4 of the present embodiment includes a semiconductor module 20, coolers 30 and 40, and connecting pipes 50 and 60. The power converter 4 may include a circuit board 70 as shown in FIG.

[0031] In the following, the stacking direction of the semiconductor module 20 and the coolers 30, 40 is the Z direction. The direction perpendicular to the Z direction and the arrangement direction of the connecting pipes 50, 60 is the X direction. The direction perpendicular to both the X direction and the Z direction is the Y direction. The X direction, the Y direction, and the Z direction are in a mutually perpendicular positional relationship. Unless otherwise specified, the planar shape refers to the shape viewed from the Z direction. The planar view from the Z direction may simply be referred to as the planar view. When describing the relative positions of two members, the position of the member closer to the cooler 30 in the Z direction may be referred to as the lower position, and the position of the member farther from the cooler 30 may be referred to as the upper position. First, the schematic configuration of each element will be described.

[0032] <Semiconductor module> The semiconductor modules 20 constitute the upper and lower arm circuits 10 described above, that is, the inverter 5 (power conversion circuit). The power conversion device 4 of this embodiment includes three semiconductor modules 20. One semiconductor module 20 provides one series circuit 12, that is, one phase of the upper and lower arm circuits 10. The multiple semiconductor modules 20 include a semiconductor module 20U that provides the upper and lower arm circuits 10U, a semiconductor module 20V that provides the upper and lower arm circuits 10V, and a semiconductor module 20W that provides the upper and lower arm circuits 10W.

[0033] All the semiconductor modules 20 have a common structure. Each semiconductor module 20 includes a semiconductor element 21, a sealing body 22, a signal terminal 23, power supply terminals 24P and 24N, an output terminal 25, and the like.

[0034] The semiconductor element 21 is formed by forming a switching element on a semiconductor substrate made of silicon (Si) or a wide band gap semiconductor with a wider band gap than silicon. The switching element has a vertical structure so that a main current flows in the thickness direction of the semiconductor substrate. Examples of wide band gap semiconductors include silicon carbide (SiC), gallium nitride (GaN), gallium oxide (Ga2O3), and diamond. The semiconductor element 21 may be called a power element, a semiconductor chip, or the like.

[0035] As an example, the semiconductor element 21 of this embodiment is formed by forming the above-mentioned n-channel type MOSFET 13 and FWD 14 on a semiconductor substrate made of SiC. The MOSFET 13 has a vertical structure so that a main current flows in the plate thickness direction of the semiconductor element 21 (semiconductor substrate). The semiconductor element 21 has main electrodes (not shown) on both sides in the plate thickness direction of itself. Specifically, as main electrodes of the switching element, it has a source electrode on the front side and a drain electrode on the back side. The source electrode is formed on a part of the front side. The drain electrode is formed on almost the entire back side.

[0036] A main current flows between the drain electrode and the source electrode. The semiconductor element 21 has a pad (not shown) that is an electrode for signals on the surface where the source electrode is formed. The semiconductor element 21 is arranged so that the plate thickness direction is approximately parallel to the Z direction. The semiconductor element 21 of this embodiment includes two semiconductor elements 21H that provide switching elements on the high side of the series circuit 12, and two semiconductor elements 21L that provide switching elements on the low side of the series circuit 12. The semiconductor elements 21H and 21L are arranged side by side in the Y direction. The two semiconductor elements 21H are arranged side by side in the X direction. Similarly, the two semiconductor elements 21L are arranged side by side in the X direction.

[0037] The four semiconductor elements 21 provide four switching elements for one series circuit 12. The semiconductor module 20 includes semiconductor elements 21 corresponding to the number of switching elements that constitute one series circuit 12. When the series circuit 12 includes two switching elements, the semiconductor module 20 includes one each of semiconductor elements 21H and 21L.

[0038] The encapsulant 22 encapsulates a portion of the other elements constituting the semiconductor module 20. The remaining portions of the other elements are exposed to the outside of the encapsulant 22. The encapsulant 22 is made of, for example, a resin. The encapsulant 22 is molded by a transfer molding method using, for example, an epoxy resin. The encapsulant 22 may be formed by using, for example, a gel.

[0039] The sealing body 22 has, for example, a substantially rectangular shape in plan view. The sealing body 22 has, as surfaces forming an outer shell, one surface 22a and a back surface 22b that is the surface opposite to the one surface 22a in the Z direction. The one surface 22a and the back surface 22b are, for example, flat surfaces. The sealing body 22 also has side surfaces 22c, 22d, 22e, and 22f that connect the one surface 22a and the back surface 22b. The side surface 22c is the surface opposite to the side surface 22d in the Y direction. The side surface 22e is the surface opposite to the side surface 22f in the X direction.

[0040] The signal terminal 23 is an external connection terminal electrically connected to a pad of the semiconductor element 21. The signal terminal 23 protrudes to the outside from the sealing body 22. For example, the signal terminal 23 connected to the pad of the semiconductor element 21H protrudes from the side surface 22c of the sealing body 22. The signal terminal 23 connected to the pad of the semiconductor element 21L protrudes from the side surface 22d of the sealing body 22. The signal terminal 23 is bent outside the sealing body 22 and extends in a direction away from the cooler 30, that is, upward. The signal terminal 23 is substantially L-shaped.

[0041] The power supply terminals 24P, 24N and the output terminal 25 are external connection terminals electrically connected to the main electrodes of the semiconductor element 21. Such external connection terminals are sometimes called main terminals. The power supply terminal 24P is electrically connected to the drain electrode of the semiconductor element 21H. The power supply terminal 24N is electrically connected to the source electrode of the semiconductor element 21L. The power supply terminal 24P is sometimes called a P terminal, a high potential power supply terminal, a positive terminal, etc. The power supply terminal 24N is sometimes called an N terminal, a low potential power supply terminal, a negative terminal, etc. The power supply terminals 24P, 24N are electrically connected to the smoothing capacitor 6. The power supply terminals 24P, 24N protrude to the outside from the side surface 22c of the sealing body 22. The protruding portions of the power supply terminals 24P, 24N are arranged side by side in the X direction.

[0042] The output terminal 25 is electrically connected to a connection point between the source electrode of the semiconductor element 21H and the drain electrode of the semiconductor element 21L, i.e., a connection point (midpoint) of the series circuit 12. The output terminal 25 protrudes to the outside from a side surface 22d of the sealing body 22. The output terminal 25 may be referred to as an O terminal, an output terminal, an AC terminal, etc. The output terminal 25 is connected to a corresponding winding 3a of the motor generator 3 via, for example, a bus bar (not shown). The external connection terminal does not protrude from the side surfaces 22e, 22f of the sealing body 22.

[0043] The semiconductor module 20 may include wiring members in addition to the above-mentioned elements. The wiring members provide a wiring function of electrically connecting the main electrodes and main terminals of the semiconductor element 21. The wiring members provide a heat dissipation function of dissipating heat from the semiconductor element 21. The wiring members are arranged, for example, so as to sandwich the semiconductor element 21 in the Z direction. As the wiring member, a board having metal bodies arranged on both sides of an insulating base material may be used, or a heat sink which is a metal member may be adopted. The heat sink is provided, for example, as a part of a lead frame. A part of the wiring member may be exposed from at least one of the one surface 22a and the back surface 22b of the sealing body 22. This can improve heat dissipation.

[0044] The semiconductor module 20 is disposed on a base plate 331 so that the back surface 22b faces a base plate 331 of a heat dissipation member 33 described later. If necessary, an electrical insulating member such as a ceramic plate or a thermally conductive member such as a TIM may be disposed between the semiconductor module 20 and the base plate 331. TIM is an abbreviation for Thermal Interface Material.

[0045] 2, the three semiconductor modules 20 are lined up in the X direction. That is, the multiple semiconductor modules 20 are arranged side by side along the X direction. The three semiconductor modules 20 are lined up, for example, in the order of semiconductor module 20U, semiconductor module 20V, and semiconductor module 20W. In the X direction, the side surfaces of adjacent semiconductor modules 20 face each other with a predetermined gap therebetween. Specifically, the side surface 22f of the semiconductor module 20U faces the side surface 22e of the semiconductor module 20V, and the side surface 22f of the semiconductor module 20V faces the side surface 22e of the semiconductor module 20W.

[0046] <Lower cooler> The cooler 30 cools the semiconductor module 20 from the rear surface 22b side. The cooler 30 is disposed below the semiconductor module 20. The cooler 30 includes a case 31. The case 31 defines a flow path 32 through which the coolant 80 flows. The case 31 is formed using a metal material such as aluminum. The case 31 is formed using a material with higher rigidity than the heat dissipation member 33 described below. As an example, the case 31 in this embodiment is formed using ADC12, which is an AlSiCu alloy.

[0047] The flow paths 32 are provided so as to overlap at least a portion of each of the semiconductor modules 20 in a plan view so as to effectively cool the semiconductor modules 20. As an example, the flow paths 32 in this embodiment are provided so as to enclose most of each of the semiconductor modules 20 in a plan view. The flow paths 32 extend along the arrangement direction of the three semiconductor modules 20, that is, along the X direction. Note that, as the coolant 80, for example, a coolant that changes phase, such as water or ammonia, or a coolant that does not change phase, such as an ethylene glycol-based coolant, can be used.

[0048] The case 31 has an opening 311 at a position overlapping with the semiconductor module 20 in a plan view. The opening 311 is provided in a wall that defines the flow path 32 and faces the semiconductor module 20. The opening 311 penetrates the facing wall. The opening 311 has, for example, a substantially rectangular shape in plan view with the X direction as its longitudinal direction. A heat dissipation member 33 is arranged in the opening 311 of the case 31.

[0049] The heat dissipation member 33 has a base plate 331 and a plurality of pin fins 332. The heat dissipation member 33 is formed using a metal material having a higher thermal conductivity than the case 31, for example, an aluminum alloy having a higher thermal conductivity. As an example, the heat dissipation member 33 in this embodiment is formed using A6063, which is an AlMgSi alloy. The heat dissipation member 33 is disposed so as to overlap with the semiconductor module 20 in a plan view.

[0050] The base plate 331 is disposed so as to close the opening 311 of the case 31. The base plate 331 has, for example, a substantially rectangular shape in plan view with the X direction as the longitudinal direction. The peripheral edge of the base plate 331 is liquid-tightly joined to the opening edge of the outer surface of the case 31 by friction stir welding or the like. This makes it possible to prevent the refrigerant 80 from leaking out of the flow path 32 through the opening 311. The base plate 331 defines the flow path 32 together with the case 31. A seal portion 34 which is a joint between the base plate 331 and the case 31 provides a liquid-tight seal.

[0051] The pin fins 332 are pin-shaped fins as shown in Figs. 3, 4, and 5. The pin fins 332 may be provided integrally with the base plate 331, or may be provided integrally by joining. The pin fins 332 are disposed in the flow passage 32 through the opening 311. The pin fins 332 protrude from the base plate 331. The pin fins 332 extend in the Z direction from one surface of the base plate 331. The pin fins 332 have a predetermined length in the Z direction. The pin fins 332 have a substantially circular or elliptical shape in plan view. The pin fins 332 are provided at a predetermined pitch in the Y direction. The pin fins 332 are provided at a predetermined pitch in the X direction.

[0052] The case 31 of the cooler 30 may be provided as a single case 31, or may be provided as a part of a housing that houses other elements of the power conversion device 4. As an example, the case 31 of this embodiment is provided as a part of a housing 35. The case 31 is provided as a part of a bottom wall 351 of the housing 35. The housing 35 has an opening to house other elements. The housing 35 has a bottom wall 351 and a side wall 352 that is continuous with the bottom wall 351 and defines a housing space together with the bottom wall 351. As an example, the housing 35 of this embodiment is box-shaped with one side open. The housing 35 is substantially rectangular in plan view in the Z direction. The semiconductor module 20, the cooler 40, the circuit board 70, and the like are arranged in the housing space of the housing 35.

[0053] An inlet pipe 36 for supplying a refrigerant to the coolers 30 and 40 and an outlet pipe 37 for discharging the refrigerant from the coolers 30 and 40 are attached to the housing 35. The inlet pipe 36 and the outlet pipe 37 are inserted through corresponding through holes (not shown) and are arranged inside and outside the housing 35. The attachment positions of the inlet pipe 36 and the outlet pipe 37 are not particularly limited. They may be attached to the bottom wall 351 or the side wall 352. The inlet pipe 36 and the outlet pipe 37 may be attached to a common surface or different surfaces. As an example, in this embodiment, the inlet pipe 36 is attached to one of the wall parts facing each other in the X direction, and the outlet pipe 37 is attached to the other wall part.

[0054] The housing 35 including the case 31 may be made of a single member or may be made of a combination of multiple members. The bottom wall 351 of the housing 35 may be made of a single member in another portion, with a combination of multiple members in a part thereof. The power conversion device 4 may include a cover (lid) (not shown) that closes the opening of the housing 35.

[0055] <Upper cooler> The cooler 40 cools the semiconductor module 20 from the one surface 22a side. The cooler 40 is disposed above the semiconductor module 20. The cooler 40 is disposed on the one surface 22a of the semiconductor module 20. An electrical insulating member such as a ceramic plate may be disposed between the cooler 40 and the semiconductor module 20 as necessary, or a thermally conductive member such as a TIM may be disposed. The cooler 40 cools the semiconductor module 20 from the opposite side to the cooler 30 in the Z direction.

[0056] The cooler 40 includes a case 41. The case 41 defines a flow path 42 through which the refrigerant 80 flows. The case 41 is formed using a metal material such as aluminum. In the Z direction, the cooler 40 is thinner than the cooler 30. The cooler 40 is, for example, a tubular body having a flat shape overall. The cooler 40 is configured to have a flow path therein by using, for example, a pair of plates (metal thin plates). At least one of the pair of plates is processed into a shape that expands in the Z direction by press processing. Thereafter, the outer peripheral edges of the pair of plates are fixed to each other by crimping or the like, and are joined to each other around the entire circumference by brazing or the like. As a result, a flow path 42 through which the refrigerant 80 can flow is formed between the pair of plates.

[0057] The flow paths 42 are provided so as to overlap at least a portion of each of the semiconductor modules 20 in a plan view so as to effectively cool the semiconductor modules 20. In this embodiment, the flow paths 42 are provided so as to overlap most of each of the semiconductor modules 20 in a plan view. The flow paths 42 extend along the arrangement direction of the three semiconductor modules 20, that is, along the X direction. The flow paths 42 cross the three semiconductor modules 20 in the X direction. In a plan view, the flow paths 42 are included in the flow paths 32. The extension length of the flow paths 42 is shorter than the extension length of the flow paths 32.

[0058] The cooler 40 may include fins. As an example, the cooler 40 of this embodiment includes fins 43. The fins 43 are arranged in a case 41 made of a pair of plates, i.e., in the flow path 42. The fins 43 are arranged so as to overlap the semiconductor module 20 in a plan view. The fins 43 are, for example, wave-shaped fins. The fins 43 have a predetermined height in the Z direction. The height of the fins 43 is shorter than the height (length) of the pin fins 332. Although not shown in the figure, the multiple fins 43 are provided at a predetermined pitch in the Y direction.

[0059] The cooler 40 is stacked on the cooler 30 via the semiconductor module 20. The cooler 40 may be pressed in the Z direction from the surface opposite to the semiconductor module 20 by a pressing member (not shown). By pressing, the cooler 40 and the semiconductor module 20, and the semiconductor module 20 and the cooler 30, are maintained in good thermal conduction. The pressing member may include, for example, a pressing plate and an elastic member. The elastic member is, for example, a member that generates a pressing force by elastic deformation of rubber or the like, or a metal spring. The elastic member is disposed between the pressing plate and the cooler 40 in the Z direction. The elastic member is elastically deformed by fixing the pressing plate at a predetermined position relative to the housing 35. The cooler 40 and the semiconductor module 20 are pressed against the cooler 30 by the reaction force of the elastic deformation.

[0060] <Connecting pipe> The connecting pipes 50 and 60 connect the cooler 30 and the cooler 40. The connecting pipe 50 supplies the refrigerant 80 to the flow paths to which the inlet pipe 36 is not connected. The connecting pipe 60 discharges the refrigerant 80 from the flow paths to which the outlet pipe 37 is not connected. As an example, the connecting pipe 50 in this embodiment supplies a portion of the refrigerant 80 supplied to the cooler 30 through the inlet pipe 36 to the cooler 40. The connecting pipe 60 discharges the refrigerant 80 that has flowed through the cooler 40 from the outlet pipe 37 via the cooler 30.

[0061] The connecting pipe 50 has a connecting flow passage 51 communicating with the flow passages 32, 42. The connecting pipe 60 has a connecting flow passage 61 communicating with the flow passages 32, 42. The connecting flow passages 51, 61 extend in the Z direction. One end of each of the connecting flow passages 51, 61 communicates with the flow passage 32, and the other end communicates with the flow passage 42. The connecting pipe 50 is connected to the vicinity of one end of the cooler 40 in the X direction. The connecting pipe 60 is connected to the vicinity of the other end of the cooler 40. Reference numeral 52 in FIG. 4 denotes a seal portion around the connecting pipe 50 provided in the cooler 30. Reference numeral 62 denotes a seal portion around the connecting pipe 60 provided in the cooler 30. The seal portions 52, 62 are provided by, for example, grommets.

[0062] The connecting pipe 50 is disposed between the connecting position of the inlet pipe 36 and the cooler 30 and the heat dissipation member 33. The connecting pipe 60 is disposed between the heat dissipation member 33 and the connecting position of the outlet pipe 37 and the cooler 30. A part of the refrigerant 80 supplied from the inlet pipe 36 flows through the flow path 32 and is discharged from the outlet pipe 37. Another part of the refrigerant 80 is supplied to the flow path 42 through the flow path 32 and the connecting flow path 51 of the connecting pipe 50. The refrigerant 80 that has flowed through the flow path 42 flows into the flow path 32 through the connecting flow path 61 of the connecting pipe 60 and is discharged from the outlet pipe 37. The connecting pipes 50 and 60, together with the cooler 40, provide a bypass path for the refrigerant 80.

[0063] As an example, in the cooler having a two-stage structure of the present embodiment, the flow rate of the refrigerant 80 flowing through the flow path 32 is greater than the flow rate of the refrigerant 80 flowing through the flow path 42. The flow path 32 is a main flow path, and the flow path 42 is a sub-flow path branched from the flow path 32. The flow rate of the flow path 32 that has passed through the branch point by the connecting pipe 50 is greater than the flow rate of the refrigerant 80 flowing through the flow path 42. The cross-sectional area of ​​the flow path 32 is greater than the cross-sectional area of ​​the flow path 42. In the Z direction, the thickness (height) of the cooler 30 is greater than the thickness of the cooler 40. The flow path 42, which is a sub-flow path, is branched from the flow path 32, which is the main flow path, via the connecting flow paths 51 and 61. The cross-sectional area of ​​each of the connecting flow paths 51 and 61 is smaller than the cross-sectional area of ​​the flow path 32. The cross-sectional area of ​​each flow path is the area of ​​a cross section perpendicular to the extension direction of the flow path, that is, the flow direction of the refrigerant. In addition, the water flow resistance of the connecting flow paths 51 and 61 is smaller than the water flow resistance of the flow path 42.

[0064] <Circuit board> Although not shown, the circuit board 70 includes a wiring board in which wiring is arranged on an insulating base material such as resin, electronic components mounted on the wiring board, connectors, etc. The mounted electronic components and wiring form a circuit. The drive circuit 7 described above is formed on the circuit board 70.

[0065] The circuit board 70 is disposed so as to overlap with the semiconductor modules 20 in a plan view in the Z direction. The circuit board 70 is disposed above the three semiconductor modules 20. The signal terminals 23 of the three semiconductor modules 20 are mounted on the circuit board 70. As an example, the circuit board 70 of the present embodiment is disposed inside the housing 35. The circuit board 70 is located above the cooler 40.

[0066] <Base plate placement> As described above, the base plate 331 of the heat dissipation member 33 is disposed so as to close the opening 311 of the case 31. In the X direction, the length L1 of the base plate 331 is shorter than the length L2 between the outer end of the connecting pipe 50 and the outer end of the connecting pipe 60. As an example, the length L1 of the base plate 331 in this embodiment is shorter than the length between the centers of the connecting pipes 50, 60 (connecting flow paths 51, 61) in the X direction. The length L1 of the base plate 331 is shorter than the length between the inner end of the connecting pipe 50 and the inner end of the connecting pipe 60. As shown in FIG. 4, the seal portion 34 between the base plate 331 and the case 31 is located inside the seal portions 52, 62 between the case 31 and the connecting pipes 50, 60.

[0067] <Summary of the First Embodiment> FIG. 6 shows a reference example. FIG. 6 corresponds to FIG. 4. In the reference example, the suffix r is added to the reference symbols of the elements related to this embodiment. The power converter 4r of the reference example also includes coolers 30r, 40r having a two-stage structure. The case 31r defining the flow path 32r is open on the entire surface facing the semiconductor module 20r. The base plate 331r is a cover that closes the opening of the case 31r. Therefore, in the X direction in which the connecting pipes 50r, 60r are arranged, the length L1r of the base plate 331r is longer than the length L2r between the outer end of the connecting pipe 50r and the outer end of the connecting pipe 60r. The other configurations of the power converter 4r are the same as those of the power converter 4 of this embodiment.

[0068] As described above, since the base plate 331r is long, there is a risk that the base plate 331r will bend outward due to water pressure, that is, will be deformed to be convex outward. If the base plate 331r is bent outward, the gap between the pin fins 332r and the case 31r will become larger, and the amount of refrigerant that passes through without hitting the pin fins 332r will increase, decreasing the cooling performance (heat exchange performance) of the cooler 30r. If the base plate 331r is deformed, the adhesion between the base plate 331r and the semiconductor module 20r will decrease, and the thermal resistance will increase. As a result, the heat dissipation performance will decrease according to the configuration of the reference example, and the structure in which the heat dissipation member 33r is added to the two-stage cooler 30r, 40r will not be fully utilized.

[0069] According to the power converter 4 of the present embodiment, in the X direction in which the connecting pipes 50, 60 are arranged, the length L1 of the base plate 331 is shorter than the length L2 between the outer ends of the connecting pipes 50, 60. Since the length of the base plate 331 constituting the heat dissipation member 33 is short in this manner, deformation of the base plate 331 due to water pressure, specifically, outward bending, can be suppressed. This can suppress an increase in the amount of refrigerant 80 that passes through without hitting the pin fins 332 due to an increase in the gap between the pin fins 332 and the case 31. In addition, it can suppress a decrease in the adhesion between the base plate 331 and the semiconductor module 20, which is caused by an increase in thermal resistance.

[0070] As described above, according to the power converter 4 of this embodiment, the decrease in heat dissipation can be suppressed. Therefore, the structure in which the heat dissipation member 33 is added to the two-stage coolers 30, 40 can be fully utilized. In other words, a power converter 4 with high heat dissipation can be provided. In this embodiment, the cooler 30 corresponds to the first cooler, and the flow path 32 corresponds to the first flow path. The cooler 40 corresponds to the second cooler, and the flow path 42 corresponds to the second flow path. The connecting pipe 50 corresponds to the first connecting portion, and the connecting flow path 51 corresponds to the first connecting flow path. The connecting pipe 60 corresponds to the second connecting portion, and the connecting flow path 61 corresponds to the second connecting flow path.

[0071] The base plate 331 (heat dissipation member 33) may be formed using the same material as the case 31, or may be formed using a material different from that of the case 31. As an example, the base plate 331 of the present embodiment is formed using a material different from that of the case 31. The thermal conductivity of the base plate 331 is higher than that of the case 31, and the rigidity of the case 31 is higher than that of the base plate 331.

[0072] As described above, since the length L1 of the base plate 331 is shorter than the length L2 between the outer ends of the connecting pipes 50, 60, it is possible to suppress deformation of the base plate 331 due to water pressure even if the rigidity of the base plate 331 is low. Since deformation is suppressed and the thermal conductivity of the base plate 331 is high, it is possible to further improve heat dissipation.

[0073] <Modification> The arrangement order of the three semiconductor modules 20U, 20V, and 20W is not limited to the above example. The semiconductor module 20U or the semiconductor module 20W may be disposed in the middle.

[0074] Although an example has been shown in which the inlet pipe 36 and the outlet pipe 37 are connected to the cooler 30, the present invention is not limited thereto. The inlet pipe 36 and the outlet pipe 37 may be connected to the cooler 40. In this case, a part of the refrigerant 80 flows from the flow path 42 to the flow path 32 of the cooler 30 via the connecting pipe 50. The refrigerant 80 that has flowed through the flow path 32 returns to the flow path 42 via the connecting pipe 60 and is discharged.

[0075] Although an example has been shown in which the cooler 30 includes the base plate 331 and the pin fins 332, the cooler 40 may include a base plate and pin fins. The length of the base plate included in the cooler 40 may be shorter than the length L2 between the outer ends of the connecting pipes 50 and 60. The case 41 of the cooler 40 has an opening on the surface facing the semiconductor module 20, and the base plate is disposed so as to close this opening. In this case, the cooler 40 corresponds to the first cooler, and the flow path 42 corresponds to the first flow path. Moreover, the cooler 30 corresponds to the second cooler, and the flow path 32 corresponds to the second flow path.

[0076] Second embodiment This embodiment is a modification based on the preceding embodiment, and the description of the preceding embodiment can be used. In the preceding embodiment, the length of the base plate constituting the heat dissipation member is shorter than the length between the outer ends of the connecting pipe. In addition, the first flow path may include a flow straightening chamber.

[0077] FIG. 7 is a plan view showing the power conversion device 4 according to this embodiment. FIG. 7 corresponds to FIG. 2. In FIG. 7 as well, signal terminals and a circuit board are omitted for convenience. The outline arrows in FIG. 7 indicate the direction in which the refrigerant flows. FIG. 8 is a cross-sectional view taken along line VIII-VIII in FIG. 7. FIG. 8 corresponds to FIG. 4. In FIG. 7 as well, a part of the housing and the circuit board are omitted. The solid arrows in FIG. 7 indicate the flow of the refrigerant.

[0078] The cooler 30 of this embodiment has a wall portion 38. The wall portion 38 protrudes from the inner wall of the case 31. The wall portion 38 may be provided integrally with the case 31 in a continuous manner, or may be provided integrally by joining. The wall portion 38 is provided between the connecting pipe 50 and the base plate 331 in the X direction. The wall portion 38 locally narrows the flow path 32. As an example, the wall portion 38 of this embodiment is connected to the bottom surface and both side surfaces in the Y direction of the inner wall of the case 31. The wall portion 38 is not connected to the upper surface of the inner wall of the case 31. Between the wall portion 38 and the upper surface of the inner wall of the case 31, there is a gap through which the refrigerant 80 can flow. The wall portion 38 divides the flow path 32 into two regions.

[0079] The flow path 32 has a heat exchange chamber 321 and a rectifying chamber 322 as regions partitioned by a wall portion 38. The heat exchange chamber 321 is a region downstream of the wall portion 38 in the longitudinal direction of the flow path 32, i.e., in the X direction. The heat exchange chamber 321 is a region closer to the exhaust pipe 37 than the wall portion 38. The pin fins 332 of the heat dissipation member 33 are arranged in the heat exchange chamber 321. The rectifying chamber 322 is a region upstream of the wall portion 38 in the X direction. The rectifying chamber 322 is a region closer to the introduction pipe 36 than the wall portion 38. In the X direction, the length of the rectifying chamber 322 is shorter than the length of the heat exchange chamber 321. As an example, the rectifying chamber 322 in this embodiment is smaller than the heat exchange chamber 321. The volume of the rectifying chamber 322 is smaller than the volume of the heat exchange chamber 321. The rectifying chamber 322 is a small room.

[0080] A connecting flow passage 51 of the connecting pipe 50 providing a refrigerant inlet for the bypass path communicates with the rectification chamber 322. A connecting flow passage 61 of the connecting pipe 60 providing a refrigerant outlet for the bypass path communicates with the heat exchange chamber 321. The heat exchange chamber 321 and the rectification chamber 322 communicate with each other through a gap above the wall portion 38. The other configurations are similar to those described in the preceding embodiment.

[0081] <Summary of the second embodiment> According to the power converter 4 of the present embodiment, it is possible to achieve the same effects as those of the preceding embodiment. Furthermore, the cooler 30 of the power converter 4 has a wall portion 38 protruding from the inner wall of the case 31. This wall portion 38 divides the flow path 32 into a heat exchange chamber 321 in which pin fins 332 are arranged, and a rectification chamber 322. The rectification chamber 322 is an area upstream of the wall portion 38, and is connected to the connecting flow path 51 of the connecting pipe 50.

[0082] In this way, the power converter 4 has the rectification chamber 322 as a front chamber of the heat exchange chamber 321 and the flow path 42. The rectification chamber 322 can receive and rectify pulsation caused by the water pump. This can suppress variation in the cooling effect. In other words, the heat dissipation can be improved. The cooler 30 corresponds to the first cooler, and the flow path 32 corresponds to the first flow path. The cooler 40 corresponds to the second cooler, and the flow path 42 corresponds to the second flow path. The connecting pipe 50 corresponds to the first connecting portion, and the connecting flow path 51 corresponds to the first connecting flow path. The connecting pipe 60 corresponds to the second connecting portion, and the connecting flow path 61 corresponds to the second connecting flow path.

[0083] <Modification> In the inner wall of the case 31, the surface to which the wall portion 38 is connected is not particularly limited. The wall portion 38 may be connected only to the bottom surface, only to the side surface, only to the top surface, or both to the side surface and the top surface.

[0084] The cooler 30 may include a wall portion provided between the connecting pipe 60 and the base plate 331 in the X direction. This wall portion divides the above-mentioned heat exchange chamber 321 into an area where the pin fins 332 are arranged and an area where the connecting pipe 60 communicates.

[0085] In a configuration in which the inlet pipe 36 and the outlet pipe 37 are connected to the cooler 40, a wall may be provided in the cooler 40 to divide the flow path 42 into a heat exchange chamber and a flow straightening chamber. In this case, the cooler 40 corresponds to the first cooler, and the flow path 42 corresponds to the first flow path. Moreover, the cooler 30 corresponds to the second cooler, and the flow path 32 corresponds to the second flow path.

[0086] (Other embodiments) The disclosure in this specification and drawings, etc. is not limited to the exemplified embodiments. The disclosure includes the exemplified embodiments and modifications by those skilled in the art based thereon. For example, the disclosure is not limited to the combination of parts and / or elements shown in the embodiments. The disclosure can be implemented by various combinations. The disclosure can have additional parts that can be added to the embodiments. The disclosure includes the omission of parts and / or elements of the embodiments. The disclosure includes the substitution or combination of parts and / or elements between one embodiment and another embodiment. The disclosed technical scope is not limited to the description of the embodiments. Some disclosed technical scopes are indicated by the description of the claims, and should be interpreted as including all modifications within the meaning and scope equivalent to the description of the claims.

[0087] The disclosure in the specification and drawings is not limited by the claims. The disclosure in the specification and drawings includes the technical ideas described in the claims, and extends to more diverse and broader technical ideas than the technical ideas described in the claims. Therefore, various technical ideas can be extracted from the disclosure in the specification and drawings without being bound by the claims.

[0088] When an element or phase is referred to as being "on," "coupled," "connected," or "coupled," it may be directly on, coupled, connected, or coupled to another element or phase, and intervening elements or phases may be present. In contrast, when an element is referred to as being "directly on," "directly coupled," "directly connected," or "directly coupled" to another element or phase, there are no intervening elements or phases. Other words used to describe relationships between elements should be construed 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 and all combinations of one or more of the associated listed items.

[0089] Spatially relative terms such as "inside," "outside," "back," "bottom," "low," "top," "top," and the like are utilized herein to facilitate the description of the relationship of one element or feature to another element or feature as depicted in the figures. Spatially relative terms may be intended to encompass different orientations of the device during use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "below" or "directly below" other elements or features would be oriented "above" the other elements or features. Thus, the term "bottom" can encompass both an orientation of top and bottom. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used in this specification would be interpreted accordingly.

[0090] The vehicle drive system 1 is not limited to the above-mentioned configuration. For example, although an example is shown in which one motor generator 3 is provided, the present invention is not limited to this. A plurality of motor generators may be provided.

[0091] Although the power conversion device 4 includes the inverter 5 as a power conversion circuit in the above example, the present invention is not limited to this. For example, the power conversion device 4 may include a plurality of inverters. The power conversion device 4 may include at least one inverter and a converter.

[0092] The number of semiconductor modules 20 is not limited to the above example. For example, one semiconductor module 20 may provide six arms 10H, 10L. One semiconductor module 20 may provide one arm, that is, one upper arm 10H or one lower arm 10L. [Explanation of symbols]

[0093] 1... drive system, 2... DC power supply, 3... motor generator, 4... power conversion device, 5... smoothing capacitor, 6... inverter, 7... drive circuit, 8... P line, 9... N line, 10... upper and lower arm circuits, 10H... upper arm, 10L... lower arm, 11... output line, 12... series circuit, 13... MOSFET, 14... FWD, 20, 20U, 20V, 20W... semiconductor module, 21, 21H, 21L... semiconductor element, 22... sealing body, 22a... one side, 22b... back side, 22c, 22d, 22e, 22f... side, 23 ...signal terminal, 24P, 24N...power supply terminal, 25...output terminal, 30...cooler, 31...case, 311...opening, 32...flow path, 321...heat exchange chamber, 322...rectification chamber, 33...heat dissipation member, 331...base plate, 332...pin fin, 34...sealing portion, 35...housing, 351...bottom wall, 352...side wall, 36...inlet pipe, 37...exhaust pipe, 38...wall portion, 40...cooler, 41...case, 42...flow path, 43...fin, 50, 60...connecting pipe, 51, 61...connecting flow path, 52, 62...sealing portion, 70...circuit board, 80...refrigerant

Claims

1. A semiconductor module (20) constituting a power conversion circuit (5); a first cooler (30) having a first flow path (32) and cooling the semiconductor module; a second cooler (40) having a second flow path (42) and cooling the semiconductor module from the opposite side to the first cooler; a first connecting portion (50) having a first connecting flow path (51) communicating with the first flow path and the second flow path; a second connecting portion (60) having a second connecting flow path (61) communicating with the first flow path and the second flow path and providing a bypass path for a part of the refrigerant together with the first connecting portion; Equipped with The first cooler includes a case (31) that defines the first flow path and has an opening at a portion that overlaps with the semiconductor module, a base plate (331) that is disposed on the case so as to cover the opening, and pin fins (332) that extend from the base plate into the first flow path, A power conversion device, wherein in an arrangement direction of the first connecting portion and the second connecting portion, the length of the base plate is shorter than the length between the outer ends of the first connecting portion and the second connecting portion.

2. the thermal conductivity of the base plate is higher than the thermal conductivity of the case; The power conversion device according to claim 1 , wherein the rigidity of the case is higher than the rigidity of the base plate.

3. The first connection portion provides a refrigerant inlet for the bypass path, The second connection portion provides a refrigerant outlet for the bypass path, 3. The power conversion device according to claim 1 or claim 2, wherein the first cooler is provided between the first connecting portion and the base plate in the arrangement direction, and has a wall portion (38) protruding from an inner wall of the case, a heat exchange chamber (321) which is a region of the first flow path downstream of the wall portion and in which the pin fins are arranged, and a straightening chamber (322) which is a region upstream of the wall portion and to which the first flow path of the first connecting portion is connected.

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