Structure, inverter module, motor, and method for manufacturing structure

Abstract

Provided is a structure (bus bar module (10)) comprising: a bus bar (30) which is made of a conductive metal and which is electrically connected to a power module (101) that has a plurality of semiconductor elements (120) and that converts current between DC and AC; and a bus bar sealing part (40) that seals at least a part of the bus bar (30) with a resin cured product obtained by curing a thermosetting resin.

Description

Structure, inverter module, motor, and method for manufacturing structure

[0001] The present invention relates to a structure, an inverter module, a motor, and a method for manufacturing the structure.

[0002] In recent years, there has been a shift from internal combustion engines to electric motors as a power source for vehicles such as automobiles. Generally, such motors are provided with a motor body and an inverter device (inverter module) (see Patent Document 1). A bus bar is disposed between the motor body and the inverter device to accommodate the flow of a relatively large current.

[0003] Japanese Patent Application Laid-Open No. 2019-173739

[0004] As motors become more powerful, the current flowing through bus bars also increases. As a result, there are concerns that heat generated by the bus bars may adversely affect elements in inverter devices. This type of bus bar is used not only between the motor body and the inverter device, but also between various other components, and there are similar concerns that heat generated may adversely affect the components.

[0005] The present invention has been made in view of the above circumstances, and has an object to provide a technique for effectively dissipating heat generated by a bus bar.

[0006] The present invention provides the following technologies. (1) A structure comprising: a bus bar made of a conductive metal and electrically connected to a power module having a plurality of semiconductor elements and performing current conversion between direct current and alternating current; and a bus bar sealing portion in which at least a portion of the bus bar is sealed with a cured resin product obtained by curing a thermosetting resin. (2) The structure according to (1), in which the thermosetting resin includes an epoxy resin or a phenolic resin. (3) The structure according to (1) or (2), in which the cured resin product has a thermal conductivity of 1 W / mK or more and 5 W / mK or less. (4) The structure according to any one of (1) to (3), in which the cured resin product has a linear expansion coefficient of 50 ppm / K or less at a temperature equal to or lower than the glass transition temperature. (5) The structure according to any one of (1) to (4), in which a current sensor is provided for detecting a current flowing through the bus bar, the current sensor being sealed in the cured resin product. (6) The structure according to (5), in which the current sensor is a Hall element coreless current sensor. (7) The structure according to any one of (1) to (6), wherein the bus bar sealing portion has a bus bar cooling channel that cools the bus bar. (8) The structure according to any one of (1) to (7), wherein the structure is provided in an AC path through which AC current flows between the power module and a stator of a rotating electric machine. (9) The structure according to any one of (1) to (7), wherein the structure is provided in a DC path through which DC current flows between the power module and a smoothing module. (10) An inverter module comprising: a power module having a plurality of semiconductor elements and performing power conversion between DC and AC; a DC path connected to the power module through which DC current flows; a smoothing module provided in the DC path and smoothing the DC current; and an AC path connected to the power module through which AC current flows, wherein a rotating electric machine is connected to the AC path, wherein the inverter module comprises the structure according to any one of (1) to (9) in the DC path between the power module and the smoothing module or in the AC path.(11) The inverter module according to (10), comprising an inverter cooling channel for cooling the inverter module and a busbar cooling channel for cooling a busbar of the structure, the inverter cooling channel and the busbar cooling channel being configured as a common channel. (12) A motor comprising the inverter module of (10) or (11) and a motor main body to which power is supplied from the inverter module. (13) A method for manufacturing the structure according to (1) to (9), comprising a busbar sealing step of sealing at least a portion of a busbar made of a conductive metal with a thermosetting resin, the busbar sealing step being performed by compression molding or transfer molding. (14) The manufacturing method according to (13), wherein the busbar sealing step is performed by compression molding, the busbar has a through-hole penetrating near an end thereof, and a positioning protrusion for attaching the through-hole of the busbar is provided inside a mold used for the compression molding. (15) The manufacturing method according to (14), wherein the molding pressure in the compression molding in the busbar sealing step is 20 MPa or less. (16) The manufacturing method according to any one of (13) to (15), wherein the thermosetting resin includes an epoxy resin or a phenolic resin.

[0007] According to the present invention, it is possible to provide a technique for effectively dissipating heat generated by a bus bar.

[0008] Fig. 1 is a cross-sectional view of a motor according to an embodiment; Fig. 2 is a cross-sectional view of a motor according to an embodiment; Fig. 3 is a plan view of a busbar module according to an embodiment; Fig. 4 is a cross-sectional view of a busbar module according to an embodiment; Fig. 5 is a flowchart showing a method for manufacturing a busbar module according to an embodiment;

[0009] <Overview> An embodiment of the present invention will be described with reference to the drawings. This embodiment provides a technology suitable for e-axle motors, achieving a low profile, compact size, improved insulation, cooling capabilities, and stable operation. To achieve this, a structure (hereinafter also referred to as a "busbar module") is used in which busbars used in inverter modules (also referred to as "inverter devices") are sealed with a highly thermally conductive resin (primarily epoxy resin) and the components are modularized (or integrated into a circuit board). The following describes examples in which the busbars are applied to inverter busbars (motor input / output busbars) connecting the inverter module to the motor body and smoothing capacitor busbars connecting the power module to a smoothing capacitor. Cooling these busbars improves the thermal environment within the motor, enabling stable operation of the power module and various electronic components on the circuit board. <Overview of Motor 1> FIG. 1 is a cross-sectional view of motor 1 taken along the rotational axis, schematically illustrating the cross-sectional structure of motor 1. FIG. 2 is a cross-sectional view perpendicular to the rotational axis of motor 1, schematically illustrating the cross-sectional structure of motor 1. The motor 1 has an inverter-driven motor body 1a and an inverter module 100 that controls the motor body 1a. In this embodiment, the inverter module 100 is attached to the upper portion of the motor body 1a in the drawing.

[0010] <Motor main body 1a> The motor main body 1a includes a motor housing 12, and a rotor 2 and a stator 4 housed inside the motor housing 12. A shaft 3 is attached to the center of the rotor 2 as an output shaft (i.e., a rotating shaft), and is rotatably supported by two bearings 3a on the left and right.

[0011] The motor housing 12 has a cylindrical portion 12a and two side plates 12b that close openings on both sides of the cylindrical portion 12a. The motor housing 12 (cylindrical portion 12a and side plates 12b) is made of, for example, resin.

[0012] The cylindrical portion 12a is provided with a connection structure 25 for connecting to the inverter module 100. In the connection structure 25, the bus bar 30 of the inverter module 100 and a coil terminal 26 extending from the coil 9 are connected.

[0013] Each side plate portion 12b is provided in a substantially disk shape and closes the end openings at both axial ends (both left and right ends in FIG. 1 ) of the cylindrical portion 12a, which has a cylindrical shape. A bearing 3a is provided at the center of each side plate portion 12b and rotatably supports the shaft 13.

[0014] The rotor 2 has a generally cylindrical shape and is made by laminating multiple disk-shaped electromagnetic steel plates. A shaft 3 is attached to the center of the rotor 2 so that it passes through in the axial direction. Additionally, multiple rectangular parallelepiped permanent magnets 5 are arranged near the outer periphery of the rotor 2 at equal intervals in the circumferential direction.

[0015] The stator 4 is substantially cylindrical and is disposed and fixed to the inner periphery of the motor housing 12 (more specifically, the cylindrical portion 12a) so as to surround the outer periphery of the rotor 2. A minute gap (air gap) is provided between the inner periphery of the stator 4 and the outer periphery of the rotor 2.

[0016] The stator 4 is made of multiple laminated thin magnetic steel plates. The stator 4 has a cylindrical yoke 6 and multiple teeth 7 arranged from the yoke 6 toward the rotor 2. A space called a slot 8 is provided between each tooth 7.

[0017] The slots 8 house coils 9. The coils 9 are wound in a distributed or concentrated manner. The slots 8 are filled with a highly thermally conductive resin, filling the gaps along with the coils 9. The resin material tightly packs the coils 9 and the stator 4, allowing for smooth heat transfer. This improves the cooling performance of the stator 4, reduces copper loss (loss due to the resistance of the coils 9 themselves), and allows for improved motor output and a more compact motor 1.

[0018] <Inverter Module 100> The inverter module 100 includes a power module 101 that converts current from AC to DC, a smoothing capacitor 130, a bus bar module 10 that connects the power module 101 to the motor main body 1a (more specifically, the coil 9 of the stator 4), and a bus bar module 10a that connects a semiconductor element (power semiconductor) 120 to the smoothing capacitor 130, all of which are housed in a housing 110. The smoothing capacitor 130 may be, for example, an electrolytic capacitor. Although the smoothing capacitor 130 is shown as an example of a smoothing module that smooths current, any configuration other than a capacitor may be used as long as it can smooth the current.

[0019] The inverter module 100 has an inverter cooling channel 102 that cools the power module 101 and a bus bar cooling channel 45 that cools the bus bar module 10 .

[0020] <Power Module 101> The power module 101 includes multiple semiconductor elements (power semiconductors) 120, a metal heat dissipation member attached to the underside of the semiconductor elements 120, and a lead frame connected to the semiconductor elements, and is sealed with resin. The lead frame protrudes or is exposed from the sealing resin and is directly or indirectly connected to the bus bar modules 10, 10a. That is, the power module 101 acquires smoothed direct current from the smoothing capacitor 130 via the bus bar module 10a, converts it to alternating current, and supplies the alternating current to the motor main body 1a via the bus bar module 10. In other words, the bus bar module 10 is provided in the AC path. The bus bar module 10a is provided in the DC path 61. The bus bar module 10 connected to the motor main body 1a and the bus bar module 10a connected to the smoothing capacitor 130 have the same basic structure. Therefore, the bus bar module 10 connected to the motor main body 1a will be described below.

[0021] <Inverter cooling channel 102> The inverter cooling channel 102 is provided on the underside of the power module 101, and a refrigerant (cooling water) flows through it to cool the power module 101. Here, heat dissipation fins provided on the underside of the power module 101 are exposed inside the inverter cooling channel 102 and come into contact with the refrigerant.

[0022] The inverter cooling flow path 102 and the bus bar cooling flow path 45 described later in FIG. 4 may be configured to have a common configuration in which the inverter cooling flow path 102 and the bus bar cooling flow path 45 are directly connected, or may be configured such that a part of the inverter cooling flow path 102 branches off midway and then merges again, or may be configured in separate locations but with the same cooling water circulating therethrough.

[0023] <Busbar module 10> Fig. 3 is a plan view of the busbar module 10. Fig. 4 is a cross-sectional view of the busbar module 10, with Fig. 4(a) being a cross-sectional view taken along X1-X1 in Fig. 3, Fig. 4(b) being a cross-sectional view taken along X2-X2 in Fig. 3, and Fig. 4(c) being a cross-sectional view taken along X3-X3 in Fig. 3.

[0024] The bus bar module 10 includes a bus bar 30 , a bus bar sealing portion 40 that seals a portion of the bus bar 30 with resin, a current sensor 20 , and a bus bar cooling channel 45 .

[0025] <Bus Bars 30> In this embodiment, the bus bars 30 include a first bus bar 31, a second bus bar 32, and a third bus bar 33 arranged in parallel. When the first bus bar 31, the second bus bar 32, and the third bus bar 33 are not distinguished from one another, they will be simply referred to as "bus bars 30." The bus bars 30 are formed into a plate shape from a conductive metal (including an alloy) such as copper or aluminum. The bus bars 30 may be bent as necessary depending on the mounting position, the position of the portion (opening) extending to the outside, and other factors. In this embodiment, the bus bars 30 are bent at the end of the bus bar sealing portion 40 (the upper end in FIG. 4A ) toward the motor main body 1a, and the end extending a predetermined length is connected to the coil terminal 26.

[0026] In this embodiment, the length of the bus bars 30 is such that the first bus bar 31 is the longest and the third bus bar 33 is the shortest, but this is not intended to be limited to this and the bus bars may be the same length, and the length may be set appropriately depending on the positional relationship with the component to be connected, etc.

[0027] The width of bus bar 30 is set appropriately depending on the specifications of motor 1, but may be, for example, 5 mm to 30 mm. The thickness of bus bar 30 is set appropriately depending on the specifications of motor 1, but may be, for example, 0.5 mm to 5.0 mm. As long as the desired performance of motor 1 can be achieved, the widths and thicknesses of first bus bar 31, second bus bar 32, and third bus bar 33 may be the same or different.

[0028] The busbar 30 has through holes 36 formed at predetermined positions (in FIG. 4 , near the lower end and near the upper bend position) that penetrate the busbar 30 in the thickness direction. The through holes 36 are aligned with the through holes formed in the busbar sealing portion 40. The through holes 36 are used for fastening to other components, etc. The through holes 36 are also used as a positioning means in a mold (inside a cavity) that is used when sealing the busbar sealing portion 40 to the busbar 30 by insert molding. That is, the through holes 36 are fitted into protrusions formed inside the cavity of the mold, thereby being positioned appropriately inside the cavity.

[0029] <Busbar Sealing Portion 40> The busbar sealing portion 40 has a structure in which at least a portion of the busbar 30 is sealed with a cured resin product formed by curing a thermosetting resin. In the present embodiment, as an example, the central portion of the busbar 30 in the longitudinal direction is sealed with the busbar sealing portion 40. Here, the first busbar 31, the second busbar 32, and the third busbar 33 are commonly sealed with the busbar sealing portion 40. The upper surface portions of both end portions of the busbar 31, the second busbar 32, and the third busbar 33 are not sealed and are exposed.

[0030] Furthermore, the current sensor 20 is disposed on the upper surface of the bus bar 30 in the portion where the bus bar sealing portion 40 seals the bus bar 30. That is, the current sensor 20 is sealed together with the bus bar 30 by the bus bar sealing portion 40. The material of the bus bar sealing portion 40 will be described later, but by using a highly thermally conductive resin and embedding a portion of the bus bar 30 in the bus bar sealing portion 40, high heat dissipation, insulation, and ease of handling can be achieved.

[0031] In the bus bar sealing portion 40, a bus bar cooling channel 45 through which a coolant (cooling water) for cooling the bus bar 30 flows is formed along the bus bar 30. The bus bar cooling channel 45 will be described in detail later.

[0032] <Current Sensor 20> The current sensor 20 is a Hall element coreless current sensor. The current sensor 20 includes a sensor substrate 21, a magnetic sensor 22 with a Hall element mounted on the sensor substrate 21, and an ASIC (Application Specific Integrated Circuit) 23. In the current sensor 20, the Hall element 22 extracts a generated magnetic field as a voltage, which is then amplified and corrected by the ASIC 23 and output to the outside through a connection terminal 24. The Hall element coreless current sensor can be made smaller and thinner than a Hall type current sensor. In this embodiment, the current sensor 20 is packaged such that a magnetic sensor 22 (Hall element) is provided on each of the first bus bar 31, the second bus bar 32, and the third bus bar 33, and the magnetic sensor 22 is amplified and corrected by a single ASIC 23. However, the current sensor 20 is not limited to this configuration and may be configured as a sensor including one magnetic sensor 22 (Hall element) and one ASIC 23. Note that if there is no demand for miniaturization, a Hall type current sensor may be used as the current sensor 20.

[0033] <Busbar Cooling Channels 45> The busbar cooling channels 45 are provided as through-holes in the busbar sealing portion 40 so as to extend along the busbars 30, and a coolant such as cooling water flows through the inside of the channels. Here, as shown in FIG. 4( c ), the channels are provided below the first busbar 31, the second busbar 32, and the third busbar 33 (toward the motor main body 1 a), at positions between the first busbar 31 and the second busbar 32, and at positions between the second busbar 32 and the third busbar 33, facing the longitudinal direction of the busbars 30. Both ends of the busbar cooling channels 45 are connected to the inverter cooling channels 102, and the same coolant (cooling water) as that for the inverter cooling channels 102 circulates through the busbar cooling channels 45.

[0034] The busbar cooling channels 45 may be provided directly in the busbar sealing portion 40 (i.e., the channel wall surface may be part of the busbar sealing portion 40), or a separate tube member may be embedded therein. By forming the busbar sealing portion 40 from a highly thermally conductive resin, heat can be effectively conducted from the busbar 30 to the busbar cooling channels 45.

[0035] <Physical Properties of Bus Bar Sealed Portion 40> The physical properties of the cured resin material constituting the bus bar sealed portion 40 are, for example, as follows. The thermal conductivity of the cured resin material is, for example, 1 W / mK or more. The lower limit of the thermal conductivity is preferably 2 W / mK or more, and more preferably 3 W / mK or more. The upper limit of the thermal conductivity is not particularly limited, but a realistic value is 5 W / mK or less.

[0036] The glass transition temperature Tg of the resin composition of bus bar sealing portion 40 is, for example, 120° C. or higher, preferably 140° C. or higher, and more preferably 160° C. or higher. By setting the glass transition temperature Tg within the above range, motor 1 can be used at high temperatures, and is more resistant to heat generation in coil 9, allowing it to be used at high output.

[0037] The linear expansion coefficient of the cured resin material of the busbar sealing portion 40 at a temperature equal to or lower than the glass transition temperature is, for example, 50 ppm / K or less. The linear expansion coefficient is preferably 40 ppm / K or less, and more preferably 30 ppm / K or less. The lower limit of the linear expansion coefficient is, for example, 1010 ppm / K or more, and preferably 15 ppm / K. Setting the linear expansion coefficient in this manner reduces the difference in the linear expansion coefficient with the busbar 30, and can suppress changes in the bonding state between the busbar sealing portion 40 and the busbar 30 due to the influence of heat (such as a decrease in bonding strength or separation). In other words, a decrease in thermal conduction between the busbar sealing portion 40 and the busbar 30 can be prevented.

[0038] <Material of Bus Bar Sealed Portion 40> The material of the bus bar sealed portion 40 is preferably a thermosetting resin. By using a thermosetting resin, the pressure required when molding the bus bar sealed portion 40 can be reduced. For example, a thermoplastic resin requires a molding pressure of about 30 MPa, but by using a thermosetting resin, the molding pressure can be reduced to about 7 to 20 MPa. When molding the bus bar sealed portion 40 while encapsulating the current sensor 20, as in this embodiment, the impact on the current sensor 20 can be reduced.

[0039] The resin composition of the bus bar sealing portion 40 preferably contains a thermosetting resin (A), a filler (B), a curing agent (C), and the like.

[0040] [Thermosetting resin (A)] Examples of the thermosetting resin (A) include epoxy resins, cyanate resins, polyimide resins, benzoxazine resins, unsaturated polyester resins, phenolic resins, melamine resins, silicone resins, bismaleimide resins, phenoxy resins, and acrylic resins. As the thermosetting resin (A), one of these may be used alone, or two or more may be used in combination. Among these, from the viewpoint of having high insulating properties, it is preferable that the thermosetting resin (A) contains an epoxy resin or a phenolic resin.

[0041] Examples of epoxy resins include bisphenol type epoxy resins such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol E type epoxy resin, bisphenol S type epoxy resin, bisphenol M type epoxy resin (4,4'-(1,3-phenylenediisopridiene)bisphenol type epoxy resin), bisphenol P type epoxy resin (4,4'-(1,4-phenylenediisopridiene)bisphenol type epoxy resin), and bisphenol Z type epoxy resin (4,4'-cyclohexidienebisphenol type epoxy resin); phenol novolac type epoxy resin, cresol novolac type epoxy resin, trisphenol group methane type novolac type epoxy resin, tetraphenol group ethoxylated epoxy resin, and the like. Examples of the epoxy resin include novolac-type epoxy resins such as benzophenone-type novolac-type epoxy resins and novolac-type epoxy resins having a condensed ring aromatic hydrocarbon structure; biphenyl-type epoxy resins; aryl alkylene-type epoxy resins such as xylylene-type epoxy resins and biphenyl aralkyl-type epoxy resins; naphthalene-type epoxy resins such as naphthylene ether-type epoxy resins, naphthol-type epoxy resins, naphthalene diol-type epoxy resins, bifunctional to tetrafunctional epoxy naphthalene resins, binaphthyl-type epoxy resins, and naphthalene aralkyl-type epoxy resins; anthracene-type epoxy resins; phenoxy-type epoxy resins; dicyclopentadiene-type epoxy resins; norbornene-type epoxy resins; adamantane-type epoxy resins; and fluorene-type epoxy resins. These may be used singly or in combination of two or more.

[0042] Among the epoxy resins, from the viewpoint of further improving heat resistance and insulation reliability, it is preferable to use one or more types selected from the group consisting of bisphenol-type epoxy resins, novolac-type epoxy resins, biphenyl-type epoxy resins, aryl alkylene-type epoxy resins, naphthalene-type epoxy resins, anthracene-type epoxy resins, and dicyclopentadiene-type epoxy resins.

[0043] Examples of phenolic resins include novolac-type phenolic resins such as phenol novolac resin, cresol novolac resin, and bisphenol A novolac resin, and resol-type phenolic resins. One of these may be used alone, or two or more may be used in combination. Among phenolic resins, phenol novolac resins are preferred.

[0044] The content of the thermosetting resin (A) is preferably 1% by mass or more, and more preferably 5% by mass or more, relative to the total amount of the resin composition of the bus bar sealed portion 40. On the other hand, the content is preferably 30% by mass or less, and more preferably 20% by mass or less, relative to the total amount of the resin composition of the bus bar sealed portion 40. When the content of the thermosetting resin (A) is equal to or greater than the above-mentioned lower limit, the handleability of the total amount of the resin composition of the bus bar sealed portion 40 is improved, making it easier to form the bus bar sealed portion 40 and improving the strength of the bus bar sealed portion 40. When the content of the thermosetting resin (A) is equal to or less than the above-mentioned upper limit, the linear expansion coefficient and elastic modulus of the bus bar sealed portion 40 are further improved, and the thermal conductivity is further improved.

[0045] [Filler (B)] The filler (B) in this embodiment is used from the viewpoint of improving the thermal conductivity of the bus bar sealing portion 40 and obtaining strength.

[0046] As the filler (B), an inorganic filler is preferred, and a thermally conductive filler is particularly preferred. More specifically, as the filler (B), from the viewpoint of achieving a balance between thermal conductivity and electrical insulation, for example, silica, alumina, boron nitride, aluminum nitride, silicon carbide, etc. may be mentioned. These may be used alone or in combination of two or more. Among them, it is preferable that the filler (B) contains alumina.

[0047] The content of the filler (B), that is, the content of the above filler, is preferably 60% by mass or more based on the total amount of the resin composition.

[0048] [Curing Agent (C)] When an epoxy resin or a phenolic resin is used as the thermosetting resin (A), the resin composition preferably further contains a curing agent (C).

[0049] The curing agent (C) can be one or more selected from the group consisting of a curing catalyst (C-1) and a phenolic curing agent (C-2). Examples of the curing catalyst (C-1) include organic metal salts such as zinc naphthenate, cobalt naphthenate, tin octoate, cobalt octoate, bisacetylacetonate cobalt(II), and trisacetylacetonate cobalt(III); tertiary amines such as triethylamine, tributylamine, and 1,4-diazabicyclo[2.2.2]octane; 2-phenyl-4-methylimidazole, 2-ethyl-4-methylimidazole, 2,4-diethylimidazole, and 2-phenyl-4-methyl-5-hydroxyimidazole; Examples of suitable curing catalysts include imidazoles such as 2-phenyl-4,5-dihydroxymethylimidazole; organic phosphorus compounds such as triphenylphosphine, tri-p-tolylphosphine, tetraphenylphosphonium tetraphenylborate, triphenylphosphine-triphenylborane, and 1,2-bis-(diphenylphosphino)ethane; phenolic compounds such as phenol, bisphenol A, and nonylphenol; and organic acids such as acetic acid, benzoic acid, salicylic acid, and p-toluenesulfonic acid, or mixtures thereof. As the curing catalyst (C-1), one of these compounds, including derivatives thereof, can be used alone, or two or more of these compounds, including derivatives thereof, can be used in combination. The content of the curing catalyst (C-1) is not particularly limited, but is preferably 0.001% by mass or more and 1% by mass or less, based on the total amount of the resin composition.

[0050] Examples of the phenolic curing agent (C-2) include novolac-type phenolic resins such as phenol novolac resins, cresol novolac resins, trisphenolmethane novolac resins, naphthol novolac resins, and aminotriazine novolac resins; modified phenolic resins such as terpene-modified phenolic resins and dicyclopentadiene-modified phenolic resins; aralkyl-type resins such as phenol aralkyl resins having a phenylene skeleton and / or biphenylene skeleton and naphthol aralkyl resins having a phenylene skeleton and / or biphenylene skeleton; bisphenol compounds such as bisphenol A and bisphenol F; and resole-type phenolic resins, and these may be used alone or in combination of two or more. Among these, from the viewpoint of improving the glass transition temperature and reducing the linear expansion coefficient, the phenolic curing agent (C-2) is preferably a novolac-type phenolic resin or a resole-type phenolic resin.

[0051] The content of the phenolic curing agent (C-2) is not particularly limited, but is preferably 1% by mass or more, more preferably 5% by mass or more, relative to the total amount of the resin composition, while the content is preferably 30% by mass or less, more preferably 15% by mass or less, relative to the total amount of the resin composition.

[0052] [Coupling Agent (D)] The resin composition may contain a coupling agent (D). The coupling agent (D) can improve the wettability at the interface between the thermosetting resin (A) and the filler (B).

[0053] The coupling agent (D) is not particularly limited, but it is preferable to use one or more coupling agents selected from, for example, epoxy silane coupling agents, cationic silane coupling agents, amino silane coupling agents, titanate coupling agents, and silicone oil coupling agents. The content of the coupling agent (D) is not particularly limited, but it is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, relative to 100% by mass of the filler (B). On the other hand, the content is preferably 3% by mass or less, more preferably 2% by mass or less, relative to 100% by mass of the filler (B).

[0054] [Phenoxy Resin (E)] The resin composition may further contain a phenoxy resin (E). The inclusion of the phenoxy resin (E) can improve the bending resistance of the bus bar sealed portion 40 and reduce the elastic modulus, thereby improving the stress relaxation force of the bus bar sealed portion 40.

[0055] Furthermore, when the phenoxy resin (E) is contained, the viscosity increases, which reduces the flowability and prevents the occurrence of voids, etc. Furthermore, when the bus bar sealing portion 40 is used in close contact with a metal member (i.e., the teeth 7), the adhesion between the metal and the cured resin composition can be improved.

[0056] Examples of the phenoxy resin (E) include phenoxy resins having a bisphenol skeleton, phenoxy resins having a naphthalene skeleton, phenoxy resins having an anthracene skeleton, and phenoxy resins having a biphenyl skeleton. Phenoxy resins having a structure containing a plurality of these skeletons can also be used.

[0057] The content of the phenoxy resin (E) is preferably, for example, 3 mass % or more and 10 mass % or less relative to the total amount of the resin composition.

[0058] [Mold Release Agent] The resin composition preferably contains a mold release agent. This can improve mold releasability after molding. Examples of mold release agents include natural waxes such as carnauba wax, synthetic waxes such as Montan acid ester wax and oxidized polyethylene wax, higher fatty acids such as zinc stearate and their metal salts, and paraffin. These may be used alone or in combination of two or more.

[0059] When a mold release agent is used, its content in the entire resin molding material is preferably 0.01 to 3 mass %, more preferably 0.05 to 2 mass %. This ensures improved mold releasability. As a result, the molding precision of the bus bar sealing portion 40 can be improved.

[0060] [Other Components] The resin composition may also contain other components such as an antioxidant and a leveling agent, provided that the effects of the present invention are not impaired.

[0061] <Method of Manufacturing Busbar Module 10> Fig. 5 is a flowchart showing a method of manufacturing the busbar module 10. The busbar module 10 is manufactured by transfer molding or compression molding.

[0062] Preparation Step S10: First, in the preparation step, a thermosetting resin that will be the material for the bus bar 30, the current sensor 20, and the bus bar sealing portion 40 is prepared.

[0063] Busbar sealing process S20: The busbar sealing process S20 includes a component placement process S21 in which components are placed inside a cavity of a mold, a resin injection process S22 in which a resin material (thermosetting resin) is injected into the cavity, and an extraction process S23 in which the molded busbar module 10 is extracted.

[0064] In the component placement step S21, the through holes 36 of the bus bars 30 are fitted into protrusions, which serve as positioning means, provided inside the cavity of the mold, and the bus bars 30 (first bus bar 31, second bus bar 32, third bus bar 33) are placed in predetermined positions. Next, the current sensor 20 is placed on the bus bars 30. Other sealing components are placed as necessary.

[0065] In the resin filling step S22, the cavity of the mold is filled with a resin material by transfer molding or compression molding. Using the above-mentioned thermosetting resin (particularly epoxy resin) as the resin material allows the molding pressure to be 20 MPa or less. As a result, adverse effects on components such as the current sensor 20 contained in the bus bar sealing portion 40 can be suppressed. If the current sensor 20 is a Hall element / coreless current sensor, a molding pressure exceeding 20 MPa may limit the types of sensors that can be used. However, keeping the molding pressure at 20 MPa or less broadens the types of sensors that can be used, improving design flexibility.

[0066] The features of this embodiment can be summarized as follows: (1) A structure (busbar module 10) comprising: a busbar 30 made of a conductive metal and electrically connected to a power module 101 having a plurality of semiconductor elements and performing current conversion between direct current and alternating current; and a busbar sealing portion 40 in which at least a portion of the busbar 30 is sealed with a cured resin product obtained by curing a thermosetting resin. (2) The structure (busbar module 10) according to (1), in which the thermosetting resin includes an epoxy resin or a phenolic resin. (3) The structure (busbar module 10) according to (1) or (2), in which the cured resin product has a thermal conductivity of 1 W / mK or more and 5 W / mK or less. (4) The structure (busbar module 10) according to any one of (1) to (3), in which the cured resin product has a linear expansion coefficient of 50 ppm / K or less at a temperature equal to or lower than the glass transition temperature. (5) The structure (busbar module 10) according to any one of (1) to (4), further comprising a current sensor 20 that detects a current flowing through the busbar 30, the current sensor 20 being sealed in the cured resin. (6) The structure (busbar module 10) according to (5), wherein the current sensor 20 is a Hall element coreless current sensor. (7) The structure (busbar module 10) according to any one of (1) to (6), wherein the busbar sealing portion 40 has a busbar cooling channel 45 that cools the busbar 30. (8) The structure (busbar module 10) according to any one of (1) to (7), wherein the structure (busbar module 10) is provided in an AC path through which AC current flows between the power module 101 and a stator 4 of a rotating electric machine (motor 1). (9) The structure (busbar module 10) according to any one of (1) to (7), wherein the structure (busbar module 10) is provided in a DC path through which a DC current flows between the power module 101 and a smoothing module (smoothing capacitor 130).(10) An inverter module 100 having a power module 101 having a plurality of semiconductor elements and performing power conversion between direct current and alternating current, a DC path connected to the power module 101 and through which a direct current flows, a smoothing module (smoothing capacitor 130) provided in the DC path and smoothing the direct current, and an AC path connected to the power module 101 and through which an alternating current flows, wherein a rotating electric machine (motor main body 1 a) is connected to the AC path, and the inverter module 100 has a structure (busbar module 10) according to any one of (1) to (9) between the power module 101 and the smoothing module (smoothing capacitor 130) in the DC path or in the AC path. (11) The inverter module 100 according to (12), comprising an inverter cooling channel 102 that cools the inverter module 100, and a bus bar cooling channel 45 that cools the bus bar 30 of the structure (bus bar module 10), the inverter cooling channel 102 and the bus bar cooling channel 45 being configured in common. (12) A motor 1 comprising the inverter module 100 of (10) or (11), and a motor main body 1a to which power is supplied from the inverter module 100. (13) A method for manufacturing the structure (inverter module 100) according to any one of (1) to (9), comprising a bus bar sealing step of sealing at least a portion of the bus bar 30 made of a conductive metal with a thermosetting resin, the bus bar sealing step being performed by compression molding or transfer molding. (14) The manufacturing method according to (13), wherein the bus bar sealing step is performed by compression molding, the bus bar 30 has a through hole 36 penetrating near an end thereof, and a positioning protrusion to which the through hole 36 of the bus bar 30 is attached is provided inside a mold used for the compression molding. (15) The manufacturing method according to (14), wherein a molding pressure in the compression molding in the bus bar sealing step is 20 MPa or less. (16) The manufacturing method according to any one of (13) to (15), wherein the thermosetting resin includes an epoxy resin or a phenol resin.

[0067] Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various other configurations can also be adopted.

[0068] This application claims priority based on Japanese Patent Application No. 2023-187431, filed November 1, 2023, the disclosure of which is incorporated herein by reference in its entirety.

[0069] REFERENCE SIGNS LIST 1 Motor 1a Motor body 2 Rotor 4 Stator 5 Permanent magnet 6 Yoke 7 Teeth portion 8 Slot 9 Coil 10 Busbar module 20 Current sensor 30 Busbar 31 First busbar 32 Second busbar 33 Third busbar 36 Through hole 40 Busbar sealing portion 45 Busbar cooling flow path 100 Inverter module 100a Motor body 101 Power module 110 Inverter housing 120 Semiconductor element 130 Smoothing capacitor (smoothing module)

Claims

1. A structure comprising: a busbar made of a conductive metal that is electrically connected to a power module that has a plurality of semiconductor elements and performs current conversion between direct current and alternating current; and a busbar sealing portion in which at least a portion of the busbar is sealed with a cured resin obtained by curing a thermosetting resin.

2. The structure of claim 1, wherein the thermosetting resin comprises an epoxy resin or a phenolic resin.

3. The structure according to claim 1 or 2, wherein the thermal conductivity of the cured resin is 1 W / mK or more and 5 W / mK or less.

4. The structure according to claim 1 or 2, wherein the linear expansion coefficient of the cured resin at a temperature equal to or lower than the glass transition temperature is 50 ppm / K or less.

5. The structure according to claim 1 or 2, further comprising a current sensor for detecting a current flowing through the bus bar, the current sensor being sealed in the cured resin.

6. The structure according to claim 5, wherein the current sensor is a Hall element coreless type current sensor.

7. The structure according to claim 1 or 2, wherein the bus bar sealing portion has a bus bar cooling channel for cooling the bus bar.

8. The structure according to claim 1 or 2, wherein the structure is provided in an AC path through which an AC current flows between the power module and a stator of a rotating electrical machine.

9. The structure according to claim 1 or 2, wherein the structure is provided in a DC path through which a DC current flows between the power module and the smoothing module.

10. An inverter module comprising: a power module having a plurality of semiconductor elements for converting power between DC and AC; a DC path connected to the power module and through which a DC current flows; a smoothing module provided in the DC path and smoothing the DC current; and an AC path connected to the power module and through which an AC current flows, wherein a rotating electric machine is connected to the AC path, and the inverter module comprises a structure according to claim 1 or 2 between the power module and the smoothing module in the DC path or in the AC path.

11. The inverter module according to claim 10, comprising: an inverter cooling passage for cooling the inverter module; and a bus bar cooling passage for cooling a bus bar of the structure, the inverter cooling passage and the bus bar cooling passage being configured in common.

12. A motor comprising the inverter module according to claim 10 and a motor body to which power is supplied from the inverter module.

13. A method for manufacturing the structure according to claim 1, comprising a busbar sealing step of sealing at least a portion of a busbar made of a conductive metal with a thermosetting resin, the busbar sealing step being carried out by compression molding or transfer molding.

14. A manufacturing method as described in claim 13, wherein the bus bar sealing step is performed by compression molding, the bus bar has a through hole near one end, and a positioning protrusion is provided inside a mold used for the compression molding to attach the through hole of the bus bar.

15. The manufacturing method according to claim 14, wherein the molding pressure in the compression molding in the bus bar sealing step is 20 MPa or less.

16. The method of claim 13, wherein the thermosetting resin comprises an epoxy resin or a phenolic resin.

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