CN114446643B

CN114446643B - Power conversion device

Info

Publication number: CN114446643B
Application number: CN202111275355.8A
Authority: CN
Inventors: 野野村昌也; 岸和田优; 渡边俊夫
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2020-11-05
Filing date: 2021-10-29
Publication date: 2024-01-19
Anticipated expiration: 2041-10-29
Also published as: JP6999777B1; CN114446643A; JP2022074617A

Abstract

The invention aims to realize miniaturization of a power conversion device in a plane direction, inhibit deflection caused by vibration and improve vibration resistance. The power conversion device (1) comprises: a power module (20) mounted on a cooling surface (11) of the cooler (10); and a first capacitor (30 a) and a second capacitor (30 b) mounted on the C-surface (40 a) and the S-surface (40 b) of the printed circuit board (40), respectively. The first capacitor (30 a) is a capacitor of a type having a higher cooling requirement than the second capacitor (30 b). The printed circuit board (40) has a C-surface (40 a) as one side of the cooling surface (11) and is disposed opposite the cooling surface (11), and the first capacitor (30 a) is thermally connected to the cooling surface (11). As a result, the area of the cooling surface (11) and the area of the printed board (40) can be reduced as compared with the case where all the capacitors are thermally connected to the cooling surface (11).

Description

Power conversion device

Technical Field

The present application relates to power conversion devices.

Background

The power conversion apparatus generally includes switching elements for converting power or power modules in which the switching elements are modularized, and a smoothing capacitor for suppressing a variation in a direct-current voltage input to the power modules.

With the recent miniaturization and high output of power conversion devices, a cooling structure for efficiently radiating heat from a power module to a cooler has been developed. On the other hand, the smoothing capacitor also has a large temperature rise due to its own heat generation or heat received from the power module, and thus needs to be cooled so as not to exceed the rated temperature of the capacitor. Therefore, a cooling structure capable of cooling not only the power module but also the smoothing capacitor is demanded.

As a cooling structure capable of cooling both the power module and the smoothing capacitor, for example, patent document 1 discloses a cooling structure in which a capacitor module insertion portion is provided in a waterway casing in which a refrigerant flow path is formed, and semiconductor module insertion portions are provided on both sides with the capacitor module insertion portion interposed therebetween.

Prior art literature

Patent literature

Patent document 1: japanese patent No. 5247745

Disclosure of Invention

Technical problem to be solved by the invention

In recent years, there has been an increasing demand for a highly durable power conversion device that has a higher output and is miniaturized in electric vehicles that have been frequently developed. In the demand for miniaturization, a limitation is sometimes imposed on one planar direction, unlike the volume of the entire apparatus. In the cooling structure described in patent document 1, since all the smoothing capacitors are disposed on the cooling surface, there is a problem in that the device expands toward the cooling surface. In addition, there are the following problems: since the cooling surface direction is enlarged, deflection due to vibration generated when the automobile is running is increased, and the device is easily broken.

The present application discloses a technique for solving the above-described problems, and an object thereof is to reduce the size of a power conversion device in a planar direction, suppress deflection due to vibration, and improve vibration resistance.

Technical means for solving the technical problems

The power conversion device according to the present application includes: a cooler having a refrigerant flow path and having at least one surface as a cooling surface; a power module mounted on the cooling surface; a printed circuit board having two or more wiring layers on which wiring patterns are formed; and a capacitor mounted on the printed circuit board, the capacitor including a first capacitor and a second capacitor, the first capacitor being a capacitor of a type having a higher cooling requirement than the second capacitor, the printed circuit board being disposed opposite the cooling surface, the first capacitor being mounted on the first surface and thermally connected to the cooling surface when the surface of the printed circuit board on the cooling surface side is the first surface and the surface of the printed circuit board on the opposite side to the first surface is the second surface, the second capacitor being mounted on the second surface.

Effects of the invention

According to the power conversion device disclosed by the application, the power conversion device comprises the first capacitor and the second capacitor with different cooling requirements, and only the first capacitor with higher cooling requirements is thermally connected with the cooling surface, so that the area of the cooling surface and the area of the printed substrate can be reduced compared with the case that all the capacitors are thermally connected with the cooling surface. Therefore, miniaturization in the planar direction can be achieved, and deflection due to vibration can be suppressed, thereby improving vibration resistance.

Drawings

Fig. 1 is a diagram showing an example of a circuit of a power conversion device according to embodiment 1.

Fig. 2 is a plan view of the power conversion device according to embodiment 1.

Fig. 3 is a side sectional view of the power conversion device according to embodiment 1.

Fig. 4 is a front cross-sectional view of the power conversion device according to embodiment 1.

Fig. 5 is a diagram showing an example of a wiring pattern of a printed circuit board of the power conversion device according to embodiment 1.

Fig. 6 is a side sectional view of the power conversion device according to embodiment 2.

Fig. 7 is a front cross-sectional view of the power conversion device according to embodiment 2.

Fig. 8 is a three-dimensional view of a cooler of the power conversion device according to embodiment 2.

Fig. 9 is a front cross-sectional view of the power conversion device according to embodiment 3.

Fig. 10 is a three-dimensional view of a cooler of the power conversion device according to embodiment 3.

Fig. 11 is a front cross-sectional view of a power conversion device according to embodiment 4.

Fig. 12 is a side sectional view of the power conversion device according to embodiment 4.

Fig. 13 is a plan view of a power conversion device according to embodiment 5.

Fig. 14 is a front cross-sectional view of the power conversion device according to embodiment 5.

Fig. 15 is a plan view of a power conversion device according to embodiment 6.

Fig. 16 is a diagram illustrating a power conversion device according to embodiment 6.

Fig. 17 is a side sectional view of a power conversion device according to embodiment 6.

Fig. 18 is a front cross-sectional view of the power conversion device according to embodiment 6.

Fig. 19 is a diagram showing an example of the first layer and the fourth layer wiring patterns of the printed circuit board of the power conversion device according to embodiment 6.

Fig. 20 is a diagram showing an example of wiring patterns of the second layer and the third layer of the printed circuit board of the power conversion device according to embodiment 6.

Fig. 21 is a diagram showing an example of the first layer and the sixth layer wiring patterns of the printed circuit board of the power conversion device according to embodiment 7.

Fig. 22 is a diagram showing an example of wiring patterns of the second layer and the fifth layer of the printed circuit board of the power conversion device according to embodiment 7.

Fig. 23 is a diagram showing an example of wiring patterns of the third layer and the fourth layer of the printed circuit board of the power conversion device according to embodiment 7.

Fig. 24 is a plan view of a power conversion device according to embodiment 8.

Fig. 25 is a side sectional view of a power conversion device according to embodiment 8.

Fig. 26 is a front cross-sectional view of the power conversion device according to embodiment 8.

Detailed Description

Embodiment 1.

Next, a power conversion device according to embodiment 1 will be described with reference to the drawings. Fig. 1 is a diagram showing an example of a circuit of a power conversion device according to embodiment 1, fig. 2 is a plan view of the power conversion device according to embodiment 1, fig. 3 is a side sectional view of a portion shown by A-A in fig. 2 seen from an arrow direction, and fig. 3 is a front sectional view of a portion shown by B-B in fig. 2 seen from the arrow direction. Fig. 5 shows an example of a wiring pattern formed on a printed board of the power conversion device according to embodiment 1. In the drawings, the same or corresponding portions are denoted by the same reference numerals.

The power conversion device 1 according to embodiment 1 is mounted on an electric vehicle, for example, and includes an inverter circuit shown in fig. 1. The inverter circuit includes a power conversion unit 2, a power smoothing unit 3, P-side wiring 4a and N-side wiring 4b (collectively referred to as wiring 4), and a control circuit unit 5.

The power conversion unit 2 includes a power module 20 including a switching element 20 a. The power module 20 converts a direct current into an alternating current by switching the switching element 20a, and drives the motor 6 through an alternating current wiring. The ac current generated by the regenerative brake or the like in the motor 6 is rectified by the ac wiring power module 20, smoothed by the smoothing capacitor 30, and stored in the battery 7.

The motor 6 for driving the electric vehicle is mostly driven by a full-bridge circuit of a three-phase alternating current type, and thus is constituted by 3 power modules 20. The switching element 20a is, for example, a MOSFET (Meatal Oxide Semiconductor Field Effect Transistor: metal oxide semiconductor field effect transistor) or an IGBT (Insulated Gate Bipolar Transistor insulated gate bipolar transistor).

The power smoothing unit 3 includes a smoothing capacitor 30 disposed at an input stage of the power conversion unit 2, and smoothes an input voltage of the battery 7, which is a lithium ion battery of several tens V to several hundreds V. The smoothing capacitor 30 smoothes an input voltage of the power module 20 which is easily vibrated by a long wiring from the battery 7, or a certain voltage of a pulse generated by the motor 6 and rectified by the power module 20. The smoothing capacitor 30 is, for example, an aluminum electrolytic capacitor, a film capacitor, a ceramic capacitor, an electric double layer capacitor, or the like.

The control circuit unit 5 outputs an appropriate signal to the power module 20, and controls the switching of the power module 20 to obtain a target motor drive frequency and torque. The voltage of the control circuit 5 is usually 20V or less, and is often electrically insulated from the power module 20 to which several tens V to several hundreds V is applied.

The power module 20 and the smoothing capacitor 30 are electrically connected through the wiring 4. Since a large current flows through the wiring 4 to reach a high temperature, a bus bar with a conductor portion exposed or a wiring pattern of the printed board 40 is used instead of a covered cable. The wiring 4 includes a P-side wiring 4a having the same potential as the high voltage portion of the battery 7 in the circuit and an N-side wiring 4b having the same potential as the low voltage portion of the battery 7 in the circuit. The material of the wiring 4 is selected from metals including copper, aluminum, tin, gold, silver, iron, an alloy thereof, a nickel alloy, and the like, for example.

In the power conversion device 1 shown in fig. 1, the smoothing capacitor 30 increases in temperature due to joule heat generation by its equivalent series resistance (Equivalent Series Resistance: hereinafter referred to as ESR) and heat received from the wiring 4 and the power supply module 20. Therefore, it is necessary that the smoothing capacitor 30 does not exceed the rated temperature.

The cooler 10, the power module 20, the printed circuit board 40, and the smoothing capacitor 30 constituting the power conversion device 1 will be described in detail with reference to fig. 2 to 5. As shown in fig. 3, the cooler 10 has a refrigerant flow path 12 through which a refrigerant 13 passes, and the refrigerant 13 flows in from the outside of the power conversion device 1 through a flow path inlet 12a and flows out to the outside of the power conversion device 1 through a flow path outlet 12 b. As the refrigerant 13, a liquid such as water or ethylene glycol, or a gas such as fluorocarbons, propane, propylene, butane, carbon dioxide, or ammonia is used.

At least one surface of the cooler 10 is formed as a cooling surface 11. The cooling surface 11 is formed by making the thermal resistance from the cooling surface 11 to the refrigerant flow path 12 smaller than the thermal resistance from the other surfaces of the cooler 10 to the refrigerant flow path 12. Specifically, the thickness of the structure from the cooling surface 11 to the refrigerant flow path 12 is reduced, and the material of the structure from the cooling surface 11 to the refrigerant flow path 12 is made of a material having high heat conductivity, or fins are provided in the refrigerant flow path 12 on the cooling surface 11 side to improve the heat conductivity.

The material of the cooler 10 is selected from metals such as aluminum, copper, tin, gold, silver, iron, alloys containing these, and nickel alloys, ceramics such as aluminum nitride and silicon carbide, and carbon-based composite materials. The cooler 10 is configured to be separable into an upper portion and a lower portion on a plane including a lower surface of the refrigerant flow path 12, for example.

As a molding method of the cooler 10, there are a method of pouring a liquid material into a mold and solidifying the liquid material, a method of cutting a block material, and the like, in addition to extrusion molding using a mold. After the upper and lower portions are formed, the upper and lower portions, including the flow path inlet 12a and the flow path outlet 12b, are fixed by screw locking, welding, bonding, or the like. Alternatively, the modeling may be performed using a device such as a 3D printer.

The power module 20 has terminals such as a P-side terminal 21a, an N-side terminal 21b, an ac terminal 23 connected to an ac wiring, and a signal terminal 22 connected to an inverter control unit. The power module 20 is mounted on the cooling surface 11 of the cooler 10, and is fixed to the cooler 10 by a pressing spring, a screw stopper, or the like. TIM (Thermal Interface Material: heat sink medium material), heat sink lubricant, adhesive having high thermal conductivity, and the like are disposed between the power module 20 and the cooling surface 11 as needed.

The printed circuit board 40 has two or more wiring layers on which wiring patterns such as the P-side wiring pattern 41a and the N-side wiring pattern 41b are formed, and in embodiment 1, has two layers, i.e., a C-plane 40a and an S-plane 40 b. The material of the wiring pattern is, for example, copper, silver, gold, tin, nickel, or the like. The material of the printed board 40 is, for example, paper phenol, paper epoxy glass composition, glass epoxy, polyimide, metal, or the like.

The capacitor mounted on the printed board 40 is a smoothing capacitor 30, and includes a first capacitor 30a and a second capacitor 30b. Further, when they do not need to be distinguished particularly, they are collectively referred to as the smoothing capacitor 30. The first capacitor 30a is a capacitor of a kind whose cooling requirement is higher than that of the second capacitor 30b.

The printed board 40 is disposed opposite to the cooling surface 11 of the cooler 10. In embodiment 1, the printed board 40 and the cooling surface 11 are arranged to face each other with the spacer 14 interposed therebetween. When the surface of the printed board 40 on the cooling surface 11 side is a first surface and the surface opposite to the first surface is a second surface, the first capacitor 30a is mounted on the first surface (i.e., the C-surface 40 a) and thermally connected to the cooling surface 11, and the second capacitor 30b is mounted on the second surface (i.e., the S-surface 40 b).

In addition, the thermal connection refers to a state in which two objects are in direct contact or a state in which they are in contact through a heat conductive member (see fig. 14). That is, a heat conductive member may be disposed between the first capacitor 30a and the cooling surface 11. The thermal conductivity of the heat conductive member is 0.1W/(m·k) or more, preferably 1.0W/(m·k) or more, and more preferably 10.0W/(m·k) or more.

The heat conductive member is, for example, TIM, heat dissipating lubricant, adhesive, potting, etc., and the material thereof is a resin such as silicon, epoxy, polyurethane, acrylic, etc. The heat conductive member has elasticity or thermosetting property, and is preferably buried without a gap between the two objects. In addition, the heat conductive member preferably has insulation.

The printed circuit board 40 is fixed to the cooler 10 by a plurality of fixing mechanisms. In embodiment 1, the fixing mechanism is a spacer 14 and a screw 15. The spacer 14 is fixed to the cooler 10, and the screws 15 are fixed to screw holes (not shown) formed on the spacer 14. The thermal conductivity of the spacer 14 and the screw 15 is 0.1W/(m·k) or more, preferably 1.0W/(m·k) or more, and more preferably 10.0W/(m·k) or more. Thereby, the heat of the printed board 40 is transferred to the cooler 10 via the spacers 14 and the screws 15.

The material of the spacer 14 and the screw 15 is selected from, for example, metals such as aluminum, copper, tin, gold, silver, iron or alloys containing these metals, nickel alloys, ceramics such as aluminum nitride and silicon carbide, resins such as engineering plastics (for example PC, POM, PA, PET, AS) and super engineering plastics (for example PEEK, PPS, PTFE, PES). The material of the spacer 14 and the screw 15 may be the same or different.

In embodiment 1, as shown in fig. 2, a plurality of screws 15 are provided at the peripheral edge portion of the printed board 40, and one screw 15 is provided at a position other than the peripheral edge portion of the printed board 40. The number of screws 15 provided in the peripheral portion of the printed circuit board 40 may be plural, or may not be provided in the central portion of the printed circuit board 40.

The fixing means for fixing the printed circuit board 40 to the cooler 10 is not limited to the screws 15, and may be bonding using an adhesive, welding or caulking with a metal portion of the printed circuit board 40, or the like. In any case, at least one of the fixing mechanisms is preferably disposed at a position other than the peripheral edge portion of the printed board 40.

The first capacitor 30a and the second capacitor 30b may be one capacitor, respectively, or may include a plurality of capacitors. The total of the capacities of the first capacitor 30a and the second capacitor 30b is about 1 muf to 100mF, and each capacitor is preferably 0.1 muf or more.

The first capacitor 30a is a capacitor of a type having a higher cooling requirement than the second capacitor 30b, and needs to be cooled more aggressively than the second capacitor 30b. Since the first capacitor 30a is thermally connected to the cooling surface 11, the cooling is performed more actively than the second capacitor 30b. The second capacitor 30b is cooled by using the printed substrate 40, the screws 15, the spacers 14 and the first capacitor 30a as a heat conduction path to the cooler 10.

In the case where the difference in cooling requirements of the first capacitor 30a and the second capacitor 30b is caused by the difference in their heat generation amounts, the heat generation amount of the first capacitor 30a is larger than that of the second capacitor 30b. In addition, in the case where the difference in the amount of heat generation is due to the difference in their capacitances, the capacitance of the first capacitor 30a is larger than that of the second capacitor 30b.

When the capacitance of the first capacitor 30a is C1 and the capacitance of the second capacitor 30b is C2, the relationship of C2< C1 holds. Further, since the impedance Z of the ideal capacitor is represented by z=1/ωc (ω: angular frequency), Z1< Z2 holds for the impedance Z1 of the first capacitor 30a and the impedance Z2 of the second capacitor 30b.

Further, according to the above-described relation of the impedances, when power is supplied from the battery 7 to the smoothing capacitor 30 or to the motor 6, I2< I1 holds for the current I1 flowing through the first capacitor 30a and the current I2 flowing through the second capacitor 30b. When the ESR levels of the first capacitor 30a and the second capacitor 30b are the same, P2 < P1 holds for the heat generation P1 by the first capacitor 30a and the heat generation P2 by the second capacitor 30b. Therefore, the temperature rise of the first capacitor 30a is larger than the temperature rise of the second capacitor 30b.

In addition, in the case where the difference in the heat generation amounts is due to the difference in the dielectric tangents thereof, the dielectric tangents of the first capacitor 30a are larger than those of the second capacitor 30 b. When the dielectric tangent of the first capacitor 30a is tan δ1 and the dielectric tangent of the second capacitor 30b is tan δ2, the relationship tan δ2< tan δ1 holds. Since the dielectric tangent is an index indicating the ratio of the capacitance C to the ESR of the capacitor, when the ESR of the first capacitor 30a is set to ESR1 and the ESR of the second capacitor 30b is set to ESR2, ESR 2< ESR1 is satisfied under the condition of c1=c2. At this time, if i1=i2, P2 < P1 holds. Therefore, the temperature rise of the first capacitor 30a is larger than the temperature rise of the second capacitor 30 b.

In addition, in the case where the difference in cooling requirements of the first capacitor 30a and the second capacitor 30b is due to their life, there is a difference in life when the first capacitor 30a and the second capacitor 30b are used under the same conditions. For example, when the lifetime of the first capacitor 30a at an arbitrary temperature is L1 and the lifetime of the second capacitor 30b is L2, L1 < L2 is satisfied. Here, since the difference between the rated temperature and the actual capacitor temperature (the longer the lifetime is), and the difference between the actual capacitor temperature and the ambient temperature (the shorter the lifetime is), the capacitor 30a having a longer lifetime when used under the same conditions may be referred to as the first capacitor 30a. In either case, by mounting the first capacitor 30a on the C-plane 40a and thermally connecting to the cooling plane 11 and mounting the second capacitor 30b on the S-plane 40b, the difference in lifetime between the first capacitor 30a and the second capacitor 30b becomes smaller than that in the case of using under the same conditions.

The printed board 40 in embodiment 1 is composed of two layers, and fig. 5 (a) shows an example of a wiring pattern on the S-plane and fig. 5 (b) shows an example of a wiring pattern on the C-plane. In these drawings, the wiring pattern is also shown in a portion overlapping with the smoothing capacitor 30 for easy understanding of the wiring pattern. The P-side wiring pattern 41a and the N-side wiring pattern 41b on the S-plane and the C-plane are preferably symmetrical in shape, except for the portion where the through hole 42 for electrically connecting the layers is formed or the periphery thereof.

The printed circuit board 40 has a connection portion 44 electrically connected to the power module 20, and also has a wiring pattern electrically connecting the connection portion 44 and the smoothing capacitor 30. The P-side terminal 21a and the N-side terminal 21b of the power module 20 are electrically connected to the P-side wiring pattern 41a and the N-side wiring pattern 41b via the connection portions 44, respectively.

The smoothing capacitor 30 is electrically connected to the P-side wiring patterns 41a and the N-side wiring patterns 41b via the capacitor terminals 31. The capacitor terminal 31 may have a linear shape such as to be inserted into a through hole of the printed board 40, or may have a curved shape such as to be connected to a pattern of the printed board 40 by surface mounting.

The connection portion 44 is a metal fitting or the like that can be inserted into a through hole of the P-side terminal 21a and the N-side terminal 21b provided in the power module 20 or mounted on the printed circuit board 40. The terminal and the metal member are connected and fixed by a screw 15 for stopping, welding, adhesion using a conductive adhesive, or the like.

When the connection portion 44 is not formed on the printed circuit board 40, wiring members such as bus bars and harnesses electrically connected to the P-side wiring patterns 41a and the N-side wiring patterns 41b are mounted on the printed circuit board 40. These wiring members are connected to the terminals directly or via other conductive structures.

According to the power conversion device 1 of embodiment 1 configured as described above, since the first capacitor 30a and the second capacitor 30b having different cooling requirements are provided, the first capacitor 30a having a higher cooling requirement is mounted on the C-plane 40a of the printed circuit board 40 and thermally connected to the cooling plane 11 of the cooler 10, and thus the area of the cooling plane 11 and the area of the printed circuit board 40 can be reduced as compared with the case where all the smoothing capacitors 30 are thermally connected to the cooling plane 11.

Further, by using the first capacitor 30a and the second capacitor 30b having different heat generation amounts and actively cooling the first capacitor 30a having a larger heat generation amount than the second capacitor 30b having a smaller heat generation amount, the temperature difference between them can be suppressed, and more efficient cooling can be performed.

As a comparative example, in the case where capacitors having the same heat generation amount are disposed on the C-surface 40a and the S-surface 40b of the printed circuit board 40, it is necessary to excessively cool the capacitor on the C-surface 40a side so that the capacitor mounted on the S-surface 40b does not exceed the rated temperature.

Further, by using the first capacitor 30a and the second capacitor 30b having different specifications such as capacitance and dielectric tangent, the degree of freedom in design with respect to the size and cost of the entire device is improved as compared with the case of using only the same type of capacitor.

In addition, by using the first capacitor 30a and the second capacitor 30b having a difference in lifetime when used under the same conditions, and actively cooling the first capacitor 30a as compared with the second capacitor 30b, the difference in lifetime can be reduced. Thus, since the total capacitance increases over the same number of years, a capacitor having a smaller initial capacitor capacitance can be selected. In general, the smaller the capacitor capacitance is, the smaller the size of the capacitor becomes, and therefore the area of the cooling surface 11 and the area of the printed board 40 can be reduced.

As another comparative example, in the case where capacitors having the same degree of lifetime are arranged on the C-face 40a and the S-face 40b of the printed circuit board 40, the lifetime of the capacitor mounted on the S-face 40b is shorter than that of the capacitor mounted on the C-face 40a, and therefore, it is necessary to design the capacitor based on the capacitor mounted on the S-face 40 b.

Further, by disposing the heat conductive member between the first capacitor 30a and the cooling surface 11, the cooling effect with respect to the first capacitor 30a is improved, and the cooling effect with respect to the printed board 40 and the second capacitor 30b, which use the first capacitor 30a as a heat conduction path, is also improved. This enables the smoothing capacitors 30 to be more densely arranged, and the printed board 40 can be further miniaturized.

In addition, since the P-side wiring pattern 41a and the N-side wiring pattern 41b of the printed board 40 are formed so as to face each other between layers, inductance generated by these wiring patterns can be reduced. This can reduce the switching loss of the power module 20 and reduce the heat received by the smoothing capacitor 30 from the power module 20.

Further, since the printed circuit board 40 has the connection portion 44, a wiring member such as a bus bar for electrically connecting the smoothing capacitor 30 and the power module 20, a terminal portion for connecting the wiring member and the printed circuit board 40, or a structure such as a terminal portion for connecting the wiring member and the power module 20 is not required.

Therefore, compared with the case of using these structures, the amount of heat received by the smoothing capacitor 30 due to heat generation caused by wiring resistance existing in the structures and current flowing through the structures can be reduced. In addition, since the wiring inductance can be reduced as compared with the case of having the above-described structure, the switching loss of the power module 20 can be reduced, and the amount of heat received by the smoothing capacitor 30 can be reduced.

Further, by fixing the printed circuit board 40 to the cooler 10 by the spacers 14 and the screws 15, the second capacitor 30b and the printed circuit board 40 have a heat conduction path to the cooler 10 in addition to being cooled by the surrounding gas phase, and thus the temperature rise is reduced. This can further increase the difference in characteristics between the first capacitor 30a and the second capacitor 30 b. In addition, the number of the first capacitors 30a can be reduced and the number of the second capacitors 30b can be increased, so that the degree of freedom in design with respect to the size or cost of the entire device is improved.

The spacer 14 is made of a material having high thermal conductivity such as copper, and is integrally formed with the cooler 10 by soldering or the like, so that the thermal resistance can be further reduced, and the temperature rise of the second capacitor 30b and the printed circuit board 40 can be further reduced. As a result, the heat of the first capacitor 30a is easily transferred to the printed circuit board 40 and the second capacitor 30b, and the temperature rise of the first capacitor 30a can be further reduced.

Further, by providing the screws 15 for fixing the printed circuit board 40 to the cooler 10 at the portions other than the peripheral edge portion of the printed circuit board 40, a heat conduction path to the cooler 10 is formed at the portions other than the peripheral edge portion of the printed circuit board 40, and therefore, the temperature rise of the smoothing capacitor 30 mounted near the central portion of the printed circuit board 40 can be reduced.

As described above, according to embodiment 1, in addition to the arrangement of the first capacitor 30a and the second capacitor 30b, the arrangement and the material of the screws 15 and the spacers 14, the wiring pattern of the printed board 40, the connection portion 44, and the like are put into effect, so that the temperature rise of the smoothing capacitor 30 can be reduced. This enables the smoothing capacitor 30 to be more densely arranged, and the area of the cooling surface 11 and the area of the printed board 40 to be further reduced.

In addition, since the printed circuit board 40 is miniaturized, when the power conversion device 1 vibrates, bending stress generated on the printed circuit board 40 is reduced, and the printed circuit board 40 is hardly broken. By fixing the portions of the printed board 40 other than the peripheral edge portion with the screws 15, the deflection of the printed board 40 due to vibration can be further suppressed. Thereby, the power conversion device 1 is miniaturized in the plane direction, and vibration resistance is improved.

Embodiment 2.

A plan view of the power conversion device according to embodiment 2 is the same as that of embodiment 1, and thus fig. 2 is used. Fig. 6 and 7 show a power conversion device according to embodiment 2, fig. 6 is a side sectional view of a portion shown by A-A in fig. 2 seen in the direction of the arrow, and fig. 7 is a front sectional view of a portion shown by B-B in fig. 2 seen in the direction of the arrow. Fig. 8 is a three-side view of the cooler according to embodiment 2.

The cooler 10 of the power conversion device according to embodiment 2 includes a recess 16 formed in the cooling surface. In embodiment 2, the number of concave portions 16 is one, but a plurality of concave portions 16 may be provided. As shown in fig. 7, the side wall portion 16a of the recess 16 is preferably integrally molded with the cooler 10.

The cooler 10 has a second cooling surface 11b as the bottom of the recess 16 and a third cooling surface 11c as the top of the side wall portion 16a of the recess 16. In the following description, the portion on which the power module 20 is mounted is referred to as a first cooling surface 11a, and the first cooling surface 11a, the second cooling surface 11b, and the third cooling surface 11c are collectively referred to as cooling surfaces.

As shown in fig. 7, the printed board 40 is fixed to the third cooling surface 11c by screws 15, and is thermally connected to the third cooling surface 11c. The first capacitor 30a is disposed inside the recess 16 and is thermally connected to the second cooling surface 11 b.

When the plurality of first capacitors 30a are disposed in the recess 16, a part or all of them are thermally connected to the second cooling surface 11b and the side surfaces of the side wall portion 16 a. In embodiment 2, as shown in fig. 7, the first capacitor 30a disposed at one end of the recess 16 is in contact with the side surface of the side wall 16 a. Further, an insulating heat conductive member may be disposed between the first capacitor 30a and the second cooling surface 11b and between the first capacitor 30a and the side wall portion 16 a.

When the direction perpendicular to the cooling surface of the cooler 10 is the height direction, the C-surface 40a of the printed board 40 is spaced apart from the second cooling surface 11b by substantially the same distance as the height dimension of the first capacitor 30 a. The C-surface 40a of the printed board 40 is spaced apart from the first cooling surface 11a by a distance substantially equal to the height of the power module 20 or a distance of several millimeters in addition to the height.

The height dimension of the side wall portion 16a is substantially the same as the distance from the second cooling surface 11b to the C-surface 40a of the printed board 40, that is, the height dimension of the first capacitor 30a. The printed board 40 is fixed to the third cooling surface 11c by a plurality of screws 15. As shown in fig. 8, cylindrical screw stopper portions 16c are provided at two positions inside the recess 16. Thereby, the parts of the printed circuit board 40 other than the peripheral edge and the three parts of the peripheral edge can be fixed to the cooler 10. Since the other structures are the same as those of embodiment 1, the description thereof is omitted here.

According to the power conversion device of embodiment 2, by disposing the first capacitor 30a in the recess 16 formed in the cooling surface 11 of the cooler 10, a part of the first capacitor 30a is thermally connected to the side wall 16a of the recess 16, and thus the first capacitor 30a can be cooled more effectively.

In addition, since the first cooling surface 11a on which the power module 20 is mounted is different in height from the second cooling surface 11b on which the first capacitor 30a is disposed, the power module 20 and the first capacitor 30a are separated, and therefore, heat generated by the power module 20 is not easily transferred to the first capacitor 30a. Therefore, the temperature rise of the first capacitor 30a can be further reduced as compared with embodiment 1. In addition, since the distance between the bottom surface of the cooler 10 and the upper surface of the second capacitor 30b is shorter than in embodiment 1, the dimension in the planar direction can be reduced, and the dimension in the height direction can be reduced.

Since the distance between the power module 20 and the printed board 40 can be set to 0 to several millimeters, the P-side terminal 21a and the N-side terminal 21b can be shortened as compared with embodiment 1, and the wiring inductance generated by each terminal can be reduced. Thereby, the switching loss in the power module 20 can be reduced, and the temperature rise of the smoothing capacitor 30 due to the temperature rise of the power module 20 and the heat received from the power module 20 can be reduced. Therefore, the areas of the first cooling surface 11a and the second cooling surface 11b can be reduced. In addition, since the terminal is shortened, the folding of the terminal due to vibration can be reduced.

Further, since the printed circuit board 40 and the third cooling surface 11c are directly fixed by the screws 15, thermal resistance is reduced as compared with the case of passing through the spacers 14, and heat of the printed circuit board 40 and the second capacitor 30b is easily transferred to the cooler 10. This can further reduce the temperature rise of the printed circuit board 40 and the second capacitor 30 b. Further, by fixing the printed board 40 to the third cooling surface 11c, deflection due to vibration is suppressed and vibration resistance is improved as compared with the case of fixing to the spacer 14.

As a result, according to embodiment 2, in addition to the same effects as those of embodiment 1, the temperature rise of the smoothing capacitor 30 and the power module 20 can be further reduced as compared with embodiment 1, and therefore they can be further densely arranged. This reduces the area of the printed board 40 and the area of the cooling surface of the cooler 10, thereby reducing the size of the power conversion device in the planar direction and the height direction and improving vibration resistance.

Embodiment 3.

A plan view of the power conversion device according to embodiment 3 is the same as that of embodiment 1, and thus fig. 2 is used. Fig. 9 is a front cross-sectional view of a portion B-B of fig. 2, showing the power conversion device according to embodiment 3, as seen from the arrow direction. Fig. 10 is a three-side view of the cooler according to embodiment 3. The power conversion device according to embodiment 3 is similar to embodiment 2 (see fig. 6) in a side cross-sectional view.

The cooler 10 of the power conversion device according to embodiment 3 has a plurality of concave portions 16 on a cooling surface thereof, and the concave portions 16 extend in the flow direction of the refrigerant 13. The plurality of first capacitors 30a are arranged in the flow direction of the refrigerant 13, and each row is accommodated in the recess 16. Thereby, all the first capacitors 30a are thermally connected to the second cooling surface 11b and the side surfaces of the side wall portion 16a directly or via the insulating heat conductive member.

In embodiment 3, the screws 15 provided at the portions other than the peripheral edge portion of the printed board 40 are fixed to the third cooling surface 11c other than the end portion of the cooler 10. Since other configurations are the same as those of embodiment 1 and embodiment 2, a description thereof will be omitted here.

According to the power conversion device of embodiment 3, in addition to the effects similar to those of embodiments 1 and 2, the first capacitor 30a mounted on the inside of the printed board 40 can be cooled by the side wall portion 16a of the recess 16, so that the cooling effect of all the first capacitors 30a can be improved, and the temperature rise of the first capacitor 30a can be further reduced.

Further, since the area of the third cooling surface 11c thermally connected to the printed circuit board 40 increases as compared with embodiment 2, it is easier to transfer the heat of the printed circuit board 40 and the second capacitor 30b to the cooler 10 than in embodiment 2. This can further reduce the temperature rise of the printed circuit board 40 and the second capacitor 30 b. This enables the smoothing capacitors 30 to be more densely arranged, and the area of the printed board 40 to be reduced, thereby improving vibration resistance.

Further, since the parts other than the peripheral edge of the printed circuit board 40 can be fixed by the third cooling surface 11c and the screws 15, the deflection of the printed circuit board 40 due to the temperature rise can be reduced. Therefore, the first capacitor 30a mounted on the inner side of the printed board 40 can be thermally connected to the second cooling surface 11 b. Therefore, the reliability of cooling the first capacitor 30a is improved.

Further, breakage of the mounted component of the printed circuit board 40 or breakage of the printed circuit board 40 due to thermal stress in the thermal cycle in which the circuit is operated and stopped can be prevented. In the same manner, the mounted components of the printed board 40 or the printed board 40 can be prevented from being damaged by external vibration, and the durability and vibration resistance of the printed board 40 can be improved.

Embodiment 4.

A plan view of the power conversion device according to embodiment 4 is the same as that of embodiment 1, and thus fig. 2 is used. Fig. 11 and 12 show a power conversion device according to embodiment 4, fig. 11 is a front sectional view of a portion shown by B-B in fig. 2 seen in the direction of the arrow, and fig. 12 is a side sectional view of a portion shown by C-C in fig. 11 seen in the direction of the arrow.

The cooler 10 of the power conversion device according to embodiment 4 has a plurality of concave portions 16, and has a side wall flow path 12c as a refrigerant flow path in a side wall portion 16a of the concave portion 16. As a result, the refrigerant 13 flows through the side wall portion 16a, and therefore the cooling effect of the third cooling surface 11c and the side surface of the side wall portion 16a is further improved than in embodiment 3. Other structures are the same as those of embodiment 3, and therefore, description thereof is omitted here.

According to embodiment 4, in addition to the same effects as those of embodiment 3, the cooling effect of the smoothing capacitor 30 and the printed circuit board 40 can be further improved as compared with embodiment 3, and the temperature rise of these can be reduced.

Embodiment 5.

Fig. 13 is a plan view of a power conversion device according to embodiment 5, and fig. 14 is a front cross-sectional view of a portion shown by D-D in fig. 13, as seen from the arrow direction. The power conversion device according to embodiment 5 is similar to embodiment 4 (see fig. 12) in a side cross-sectional view.

The cooler 10 of the power conversion device according to embodiment 5 has a plurality of concave portions 16 and side wall flow paths 12c, as in embodiment 4. The positional relationship between the first capacitor 30a and the second capacitor 30b and the positional relationship between the through holes 42 formed in the printed board 40 are different from those in embodiment 4. Other structures are the same as those of embodiment 4, and therefore, description thereof is omitted here.

In the plan view of fig. 13, the first capacitor 30a mounted on the back surface of the printed circuit board 40 is shown in broken lines. As shown in fig. 13, the first capacitor 30a and the second capacitor 30b are arranged at positions that do not overlap with the cooling surface of the cooler 10 in the vertical direction. As shown in fig. 14, the second capacitor 30b is disposed so as to face the third cooling surface 11c with the printed board 40 interposed therebetween.

A heat conductive member 50 is disposed between at least a portion of the third cooling surface 11c and the printed board 40, and the printed board 40 and the third cooling surface 11c are thermally connected by the heat conductive member 50. The heat conductive member 50 preferably has elasticity, and when insulation is required between the wiring of the printed circuit board 40 and the cooler 10, an insulating member is used.

The printed board 40 has a through hole 42 for electrically connecting the layers at a portion facing the third cooling surface 11c via the heat conductive member 50. The through holes 42 are preferably conductive paths for electrically connecting the P-side wiring patterns 41a or the N-side wiring patterns 41b formed on the C-side, S-side, or inner layer of the printed board 40. When the temperature of the first capacitor 30a is lower than the temperature of the second capacitor 30b, it is preferable that a part of the hole 42 is arranged as much as possible within 10mm around the second capacitor 30 b. However, the configuration of the through holes 42 is not limited thereto.

The cooling requirement of the second capacitor 30b is lower than that of the first capacitor 30a, but the temperature rise is not small depending on the heat or the atmospheric temperature received from the first capacitor 30a, the wiring pattern, the power module 20, and the like, in addition to self-heat generation. In the same manner, the printed board 40 increases in temperature due to self-heat generation or the like in the wiring pattern. In particular, in a power conversion device that handles a large current, the wiring pattern of the printed circuit board 40 in which these currents are concentrated may be at a high temperature as compared with the smoothing capacitor 30 in which the number of parallel smoothing capacitors that are used to distribute the current can be increased. Therefore, a means for reducing the temperature rise of the second capacitor 30b and the printed circuit board 40 is sometimes required.

In embodiment 5, the first capacitor 30a and the second capacitor 30b are arranged so as not to overlap the cooling surface of the cooler 10 in the vertical direction, and therefore the amount of heat received by the second capacitor 30b from the first capacitor 30a can be reduced. Therefore, the temperature rise of the second capacitor 30b due to the first capacitor 30a can be reduced.

Further, since the second capacitor 30b is disposed to face the third cooling surface 11c via the printed board 40, the heat of the second capacitor 30b is easily transferred to the cooler 10. Further, by disposing the heat conductive member 50 between the printed board 40 and the third cooling surface 11c, the printed board 40 can be thermally connected to the third cooling surface 11c more reliably, and the cooling effect can be improved.

Further, since the temperature rise of the second capacitor 30b can be reduced, the capacitance or number of the second capacitors 30b can be increased, and the capacitance or number of the first capacitors 30a can be reduced. Further, by using the heat conductive member 50 having elasticity, vibration of the printed board 40 can be reduced, and vibration resistance can be improved.

Further, since the heat of the wiring pattern on the inner side of the printed board 40 in particular can be transferred to the third cooling surface 11c via the conductive member 50, the heat transferred from the printed board 40 to the first capacitor 30a can be reduced, and as a result, the temperature rise of the first capacitor 30a can be reduced.

Further, by providing the through hole 42 in the printed board 40, heat transfer through the through hole 42 is possible, and an effect of equalizing the temperatures of the C-plane and the S-plane, or the first capacitor 30a and the second capacitor 30b can be obtained. Particularly, the cooling effect on the first capacitor 30a is sufficiently good, and when the temperature of the first capacitor 30a is lower than the temperature of the second capacitor 30b, a heat conduction path for transmitting the heat of the second capacitor 30b from the S surface to the C surface via the through hole 42, the first capacitor 30a, and the cooler 10 can be provided, whereby the second capacitor 30b can be cooled efficiently.

According to embodiment 5, in addition to the same effects as those of embodiment 4, the cooling effect of the second capacitor 30b and the printed circuit board 40 can be further improved than those of embodiment 4, and the temperature rise of these can be reduced.

Embodiment 6.

Fig. 15 is a plan view of a power conversion device according to embodiment 6, fig. 16 is a plan view of the printed circuit board removed from fig. 15, fig. 17 is a side sectional view of a portion shown by E-E in fig. 15 seen in the direction of the arrow, and fig. 18 is a front sectional view of a portion shown by F-F in fig. 15 seen in the direction of the arrow. Fig. 19 and 20 show an example of a wiring pattern formed on a printed board of the power conversion device according to embodiment 6.

As shown in fig. 15, in the power conversion device according to embodiment 6, most of the cooling surface of the cooler 10 is covered with the printed board 40. When the printed board 40 is removed, as shown in fig. 16, a plurality of concave portions 16 are formed in the cooler 10. The second cooling surface 11b, which is the bottom of the plurality of concave portions 16, is rectangular, and long sides of the rectangular are arranged so as to face each other, thereby forming a plurality of elongated third cooling surfaces 11c.

The power module 20 includes a switching element 20a constituting a three-phase ac inverter circuit. In embodiment 6, one power module 20 includes 2 switching elements 20a, which correspond to the upper and lower arms of the bridge circuit portion in the inverter circuit diagram shown in fig. 1. By using three such power modules 20, the power conversion section 2 of the three-phase ac inverter is constituted.

The plurality of power modules 20 constituting the U-phase, V-phase, and W-phase are arranged so as to face each other along the long sides thereof, and the plurality of concave portions 16 extending in the long side direction of the power modules 20 are formed adjacent to the power modules 20. In embodiment 6, the top of the side wall portion 16a of the recess 16 is the third cooling surface 11c, and is also the first cooling surface 11a on which the power module 20 is mounted.

The first capacitors 30a accommodated in the recess 16 are arranged along the longitudinal direction of the power module 20. The number of first capacitors 30a accommodated in each recess 16, that is, the number of first capacitors 30a adjacent to each power module 20 is preferably equal. Although the arrangement of the second capacitors 30b is not particularly limited, it is preferable that the number of the power modules 20 and the number of the second capacitors 30b which are adjacent to each other via the printed board 40 are equal.

A distance for ensuring insulation between the printed circuit board 40 and the power module 20 is required, but in order not to excessively long the P-side terminal 21a and the N-side terminal 21b, it is preferable that the distance be approximately 0.5mm to 20 mm. The upper surface of the power module 20 is a heat radiation surface except for the terminal portion, and the heat radiation surface of the power module 20 and the printed board 40 may be in contact with each other with an insulating heat conductive member interposed therebetween.

As shown in fig. 15, the printed board 40 is formed with a long hole 45 for passing the signal terminal 22 and the ac terminal 23 extending from the power module 20. Among them, there is also a method of connecting the control circuit unit 5 or the motor 6 to the power module 20 via a connector or the like mounted on the printed board 40. In this case, a through hole in which the side surface of the hole is plated with copper or the like is formed in the printed board 40, and the signal terminal 22 and the ac terminal 23 are electrically connected and fixed by soldering, or the like.

The printed board 40 in embodiment 6 is composed of four layers, where (a) of fig. 19 shows an example of a wiring pattern of a first layer, (b) of fig. 19 shows an example of a wiring pattern of a fourth layer, (a) of fig. 20 shows an example of a wiring pattern of a second layer, and (b) of fig. 20 shows an example of a wiring pattern of a third layer. The P-side wiring pattern 41a and the N-side wiring pattern 41b are formed in the same manner on the first layer (S-side) and the fourth layer (C-side), and the second capacitor 30b is mounted on the first layer and the first capacitor 30a is mounted on the second layer.

The second layer and the third layer are substantially the same pattern except that the second layer is the N-side wiring pattern 41b and the third layer is the P-side wiring pattern 41 a. However, the structure of the printed circuit board 40 is not limited to this, and the printed circuit board 40 may be formed of two layers without the second layer and the third layer, or may be a printed circuit board 40 having more layers.

According to embodiment 6, since the cooler 10 having the plurality of concave portions 16 is used to cool the first capacitor 30a with the second cooling surface 11b and the side surface of the side wall portion 16a and to cool the power module 20 with the third cooling surface 11c, the area corresponding to the first cooling surface 11a in embodiments 3 to 5 can be reduced.

When the power module 20 and the cooler 10 are reliably fixed, the P-side terminal 21a and the N-side terminal 21b extending from the power module 20 are inserted into the connection portion 44 of the printed circuit board 40, thereby functioning as a fixing mechanism for fixing the printed circuit board 40 to the cooler 10. Therefore, since the portion other than the peripheral edge portion of the printed board 40 can be fixed without using the screw 15, the deflection due to the vibration can be suppressed, and the vibration resistance can be improved.

Further, by equalizing the number of first capacitors 30a adjacent to each power module 20 and the number of second capacitors 30b close to each power module 20, the wiring resistance and the wiring inductance from the first capacitors 30a and the second capacitors 30b to the power modules 20 can be equalized. Therefore, the currents flowing through the respective first capacitors 30a and the respective second capacitors 30b are almost equal, and the temperature increases are also almost equal.

Accordingly, it is not necessary to design a cooling area or a cooling structure that matches the smoothing capacitor 30 having the largest temperature rise, and therefore, the area of the cooling surface can be reduced or the cooling structure can be simplified, thereby achieving cost reduction.

In addition, since the distance between each power module 20 and the center of printed board 40 is shorter than in embodiments 1 to 5 described above, the wiring resistance and the wiring inductance can be reduced, and therefore, the temperature rise of the wiring and the switching loss at power module 20 can be reduced. This reduces the amount of heat received by the smoothing capacitor 30 from the wiring and the power module 20, and suppresses the temperature rise of the smoothing capacitor 30.

When the upper surface of the power module 20, which is the heat radiation surface, is thermally connected to the printed board 40 via the heat conduction member, a heat conduction path is formed through which the heat of the power module 20 is transmitted to the screw 15, the first capacitor 30a, and the cooler 10 via the printed board 40. This heat conduction path is applied to a case where there is a margin for the rated temperature of the printed circuit board 40 and the smoothing capacitor 30, but there is no margin for the rated temperature of the power module 20, and thus, the temperature rise of the power module 20 can be suppressed.

In the printed board 40, since the P-side wiring patterns 41a and the N-side wiring patterns 41b are opposed in parallel to each other in a wide area in the second layer and the third layer, wiring inductance generated in the P-side wiring patterns 41a and the N-side wiring patterns 41b can be reduced. Therefore, switching loss at the power module 20 can be reduced, heat received by the first capacitor 30a from the power module 20 can be reduced, and a temperature rise of the first capacitor 30a can be reduced.

Further, by forming the wiring patterns as wide as the second layer and the third layer, heat is easily diffused throughout the substrate, and heat is easily transferred from the screws 15 disposed at the peripheral edge portion of the printed substrate 40 to the cooler 10. Therefore, the cooling effect of the printed board 40 can be improved, and the temperature rise of the printed board 40 can be reduced.

Embodiment 7

The power conversion device according to embodiment 7 is the same as that of embodiment 6 described above except for the wiring pattern of the printed circuit board 40, and therefore only the wiring pattern will be described here. The printed board 40 according to embodiment 7 is composed of six layers, where (a) of fig. 21 shows an example of a wiring pattern of the first layer, (b) of fig. 21 shows an example of a wiring pattern of the sixth layer, (a) of fig. 22 shows an example of a wiring pattern of the second layer, (b) of fig. 22 shows an example of a wiring pattern of the fifth layer, and fig. 23 shows an example of wiring patterns of the third layer and the fourth layer.

The third and fourth layers of the printed substrate 40 are heat dissipation layers, and the other is a wiring layer. The first layer (S surface) and the sixth layer (C surface) have the same wiring pattern as the first layer and the fourth layer (see fig. 19) of embodiment 6 described above, except that the heat dissipation pattern 43 is provided at the peripheral edge portion. The second layer and the fifth layer have the same wiring pattern as the second layer and the third layer (see fig. 20) of embodiment 6 described above, except that the heat dissipation pattern 43 is provided at the peripheral edge portion.

A heat dissipation pattern 43 for mainly transporting heat of the printed substrate 40 is formed on almost the entire surface of the heat dissipation layer shown in fig. 23. The heat dissipation pattern 43 extends to screw holes in the peripheral edge portion of the printed board 40. The heat dissipation pattern 43 formed at the peripheral edge portion of the wiring layer is electrically and thermally connected to the heat dissipation pattern 43 of the heat dissipation layer through the through hole 42. The heat dissipation layer is electrically and thermally connected to the screw 15 and the cooler 10 through the heat dissipation pattern 43 formed on the C-plane or the S-plane.

According to embodiment 7, since the printed board 40 has the heat dissipation layer, heat of the printed board 40 is easily transferred to the cooler 10, and the temperature rise of the printed board 40 can be reduced. If the temperature of the printed circuit board 40 is lower than the first capacitor 30a, the heat of the first capacitor 30a can be transferred from the printed circuit board 40 to the cooler 10, and the area of the second cooling surface 11b for cooling the first capacitor 30a can be reduced.

Further, the heat dissipation layer is electrically connected to the cooler 10 and is at the same potential, and therefore, the heat dissipation layer serves as a shield for noise reduction for radiating the power module 20 to a region above the heat dissipation layer at the time of switching. Therefore, the control circuit unit 5, which is susceptible to switching noise, can be disposed closer to the power module 20 than in the case where there is no heat dissipation layer, thereby achieving downsizing of the power conversion device. Further, by including the heat dissipation layer which is a thin metal plate, the printed board 40 is less likely to flex than a case without the heat dissipation layer, and vibration resistance is improved.

Embodiment 8.

Fig. 24 shows a power conversion device according to embodiment 8, fig. 25 is a side sectional view of a portion shown by G-G in fig. 24 seen in the direction of the arrow, and fig. 26 is a front sectional view of a portion shown by H-H in fig. 24 seen in the direction of the arrow.

The power conversion device according to embodiment 8 has a cover 60 facing the S-surface 40b, which is the second surface of the printed circuit board 40, in addition to the same configuration as the power conversion device according to embodiment 4 (see fig. 11 and 12). The cover case 60 includes a cover main surface 61 covering the upper portion of the printed substrate 40 and the second capacitor 30b, and a cover leg 62 supporting the cover main surface 61.

The material of the cover 60 is selected from metals such as aluminum, copper, tin, gold, silver, iron, alloys containing these, nickel alloys, ceramics such as aluminum nitride and silicon carbide, and carbon-based composite materials, and the thermal conductivity is preferably 10.0W/(m·k) or more. As a method for manufacturing the cover 60, sheet metal may be punched and formed, or a material in a molten or deformable state may be put into a mold and fixed.

The cover case 60 is thermally connected to the top surface of the second capacitor 30b via a thermally conductive member as needed by the cover main surface 61. As shown in fig. 26, the cover legs 62 extend from the end portions of the cover main surface 61 in the direction perpendicular to the cooling surface 11, and are fixed to the printed board 40 and the cooler 10 by the screws 15. Thus, the cover 60, the screw 15, and the cooler 10 are thermally connected, and if the cover 60 is a conductive member, the cover is also electrically connected.

In the example shown in fig. 24 to 26, the cover 60 is configured to cover only the upper portion of the printed circuit board 40, but may cover the upper portion of the power module 20. In this case, it is necessary to determine the range and shape of the cover case 60 so that the cover case 60 does not interfere with the respective terminal portions of the power module 20.

According to embodiment 8, in addition to the same effects as those of embodiment 4 described above, the second capacitor 30b has a thermal path from the lid case 60 side to the cooler 10, and therefore, the temperature rise of the second capacitor 30b can be reduced. This can reduce the temperature rise of the first capacitor 30a, and can further reduce the area of the cooling surface.

In addition, by expanding the cover case 60 also to the power module 20 side, the power module 20 has a thermal path from the cover case 60 side to the cooler 10, and thus the temperature rise of the power module 20 can be reduced. This can reduce the area of the first cooling surface 11 a.

Further, the cover case 60 presses the entire second capacitor 30b and the printed circuit board 40 against the cooler 10 from above, thereby suppressing deflection due to vibration and improving vibration resistance. In addition, by providing the cover 60 with conductivity, the cover functions as a shield for reducing noise radiated from the power module 20 during switching. In this way, the control circuit unit 5 can be disposed closer to the power module 20, and the power conversion device can be miniaturized.

While various exemplary embodiments and examples have been described in this disclosure, the various features, aspects and functions described in 1 or more embodiments are not limited to the application of the particular embodiments, and may be applied to the embodiments alone or in various combinations. Accordingly, numerous modifications not illustrated are considered to be included in the technical scope disclosed in the present specification. For example, the case where at least one component is modified, added, or omitted, and the case where at least one component is extracted and combined with the components of other embodiments is included.

Industrial applicability

The present application can be used as a power conversion device, particularly as a power conversion device mounted on a vehicle power supply of an electric vehicle.

Description of the reference numerals

1. Power conversion device

2. Power conversion unit

3. Power smoothing part

4. Wiring

4a P side wiring

4b N side wiring

5. Control circuit part

6. Motor with a motor housing having a motor housing with a motor housing

7. Battery cell

10. Cooling device

11. Cooling surface

11a first cooling surface

11b second cooling surface

11c third cooling surface

12. Refrigerant flow path

12a flow passage inlet

12b flow path outlet

12c side wall flow path

13. Refrigerant and method for producing the same

14. Spacing piece

15. Screw bolt

16. Concave part

16a side wall portion

16c screw stop

20. Power module

20a switching element

21a P side terminal

21b N side terminal

22. Signal terminal

23. AC terminal

30. Smoothing capacitor

30a first capacitor

30b second capacitor

31. Capacitor terminal

40. Printed substrate

40a C face (first face)

40b S face (second face)

41a P side wiring pattern

41b N side wiring pattern

42. Through hole

43. Heat dissipation pattern

44. Connecting part

45. Long hole

50. Heat conducting member

60. Cover shell

61. Main surface of cover plate

62. And a cover plate leg.

Claims

1. A power conversion apparatus, comprising:

a cooler having a refrigerant flow path, at least one surface being formed as a cooling surface;

a power module mounted on the cooling surface;

a printed board having two or more wiring layers on which wiring patterns are formed; and

a capacitor mounted on the printed board,

the capacitor includes a first capacitor and a second capacitor, the first capacitor being a capacitor of a kind whose cooling requirement is higher than that of the second capacitor,

The printed board is disposed opposite to the cooling surface, and when a surface of the printed board on one side of the cooling surface is a first surface and a surface of the printed board on the opposite side of the first surface is a second surface,

the first capacitor is mounted on the first surface and thermally connected to the cooling surface, the second capacitor is mounted on the second surface,

the first capacitor and the second capacitor are smoothing capacitors.

2. The power conversion device of claim 1, wherein,

the first capacitor generates a larger amount of heat than the second capacitor.

3. The power conversion device of claim 2, wherein,

the first capacitor has a larger capacitance than the second capacitor.

4. The power conversion device of claim 2, wherein,

the first capacitor has a dielectric tangent greater than that of the second capacitor.

5. The power conversion apparatus according to any one of claims 1 to 4,

the first capacitor and the second capacitor have a difference in lifetime when used under the same conditions,

the first capacitor is mounted on the first surface and thermally connected to the cooling surface, and the second capacitor is mounted on the second surface, so that a difference between life spans of the first capacitor and the second capacitor becomes smaller than a difference between life spans when used under the same condition.

6. The power conversion apparatus according to any one of claims 1 to 4,

the cooler includes a recess formed in the cooling surface,

the cooling surface includes a second cooling surface as a bottom of the recess and a third cooling surface as a top of a side wall portion of the recess,

the printed substrate is fixed on the third cooling surface and is thermally connected with the third cooling surface,

the first capacitor is disposed in the recess and is thermally connected to the second cooling surface.

7. The power conversion device of claim 6, wherein,

the cooler has the refrigerant flow path inside the side wall portion.

8. The power conversion device of claim 6, wherein,

the plurality of first capacitors are disposed in the recess, and a part or all of the plurality of first capacitors are thermally connected to the second cooling surface and the side surface of the side wall portion.

9. The power conversion device of claim 6, wherein,

comprises a heat conducting member arranged between the printed substrate and the third cooling surface.

10. The power conversion device of claim 6, wherein,

The printed circuit board has a through hole for electrically connecting the layers at a position facing the third cooling surface.

11. The power conversion device of claim 6, wherein,

the power module includes a switching element constituting a three-phase ac inverter circuit, and the plurality of power modules constituting a U-phase, a V-phase, and a W-phase are arranged so as to face each other along a long side thereof, and the plurality of concave portions extending in a long side direction of the power module are formed adjacent to the power module.

12. The power conversion device of claim 11, wherein,

the number of the first capacitors adjacent to each of the power modules is equal.

13. The power conversion apparatus according to any one of claims 1 to 4,

the first capacitor and the second capacitor are disposed at positions not overlapping the cooling surface of the cooler in the vertical direction.

14. The power conversion apparatus according to any one of claims 1 to 4,

the printed substrate has a connection portion electrically connected to the power module, and has a wiring pattern electrically connecting the connection portion and the capacitor.

15. The power conversion apparatus according to any one of claims 1 to 4,

the printed circuit board has one or more heat dissipation layers different from the wiring layers, and the heat dissipation layers are thermally and electrically connected to the cooler.

16. The power conversion apparatus according to any one of claims 1 to 4,

the printed circuit board comprises a plurality of fixing mechanisms for fixing the printed circuit board to the cooler, wherein at least one of the fixing mechanisms is arranged at a position except for the periphery of the printed circuit board.

17. The power conversion apparatus according to any one of claims 1 to 4,

comprising a cover case opposite to the second face of the printed substrate, the cover case being thermally connected to the second capacitor and the cooler.