Switching modules and inverters

Abstract

To realize higher-performance switching modules and inverters. [Solution] The switching module 120A comprises a substrate 40 on which conductors 51, 52, and 53 connecting a plurality of switching elements 30 are formed on the upper surface, and whose lower surface is in close contact with a predetermined conductive heat sink 42. The substrate 40 includes a plurality of conductive layers 61, 62 connected to the conductors 51, 52. Each of the conductive layers 61, 62 faces the other via an electrical insulating layer 60, thereby providing an energy storage structure 63 composed of a plurality of stacked energy storage elements inside the substrate 40. The capacitance C of the first energy storage element CE1, which is composed of the conductor 53 and the uppermost conductive layer CL1, is configured to be smaller than the capacitance C of other energy storage elements CE2, etc.

Description

Technical Field

[0001] The disclosed technology relates to a switching module and an inverter in which switching control is performed, and particularly to a switching module and an inverter suitable for in-vehicle applications.

Background Art

[0002] In recent years, the electrification of automobiles has been remarkable. DC power supplied from a high-voltage battery is converted into AC power by performing switching control with an inverter. The motor is rotationally driven by the AC power, and the automobile runs. As the performance of the inverter improves, the switching control is becoming faster.

[0003] When the switching control becomes faster, the switching element becomes hot. Therefore, a high-performance switching element is required, which causes an increase in the cost of the switching module and thus the inverter. Furthermore, electromagnetic noise is generated, which causes malfunctions of electrical equipment close to the inverter and communication failures.

[0004] In addition, as this type of electromagnetic noise, normal mode noise caused by current (normal mode current) flowing to the battery via electrical wiring and common mode noise caused by current (common mode current) flowing via stray capacitance (parasitic capacitance) and ground (earth) together with the electrical wiring are known.

[0005] As an electronic component that enables suppression of normal mode noise, a smoothing capacitor is usually installed in the inverter. However, the smoothing capacitor also generates heat along with the switching control. Therefore, it is necessary to efficiently dissipate the heat of the smoothing capacitor. In particular, the size of the smoothing capacitor for in-vehicle use is large and its importance is high.

[0006] In response to these issues, the present inventor has previously proposed a technology that can solve these problems (Patent Document 1). In this technology, a substrate (electrical insulating material) on which an inverter circuit is mounted is provided so as to be in contact with a heat sink (heat dissipation material). A layered energy storage structure that can function as a smoothing capacitor is provided inside the substrate.

[0007] This energy storage structure allows for miniaturization or elimination of smoothing capacitors. The energy storage structure also facilitates heat dissipation. Furthermore, the energy storage structure effectively suppresses common-mode noise. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2024-48494 [Overview of the project] [Problems that the invention aims to solve]

[0009] As the inventors continued development with respect to the above-described technology, they found room for improvement. This specification discloses the newly discovered improved technology. [Means for solving the problem]

[0010] The disclosed technology relates to a switching module comprising a substrate having a conductor for connecting multiple switching elements formed on its upper surface, and the lower surface of the substrate being in close contact with a predetermined heat dissipation member having conductivity.

[0011] The substrate includes a plurality of conductive layers connected to the conductor, and each of the conductive layers faces another via an electrical insulating layer, thereby providing an energy storage structure composed of a plurality of stacked energy storage elements inside the substrate. The capacitance of the first energy storage element, which is composed of the conductor and the uppermost conductive layer, is configured to be smaller than the capacitance of the other energy storage elements.

[0012] With this switching module, even when switching control is performed, the conductor faces multiple energy storage elements, including a negative electrode conductive layer whose potential does not change. Therefore, no current flows through the paths passing through these energy storage elements. The common-mode current value is zero. Consequently, common-mode noise can be almost completely eliminated.

[0013] However, in this case, a problem was identified where unnecessary current flowed due to the first energy storage element, resulting in a decrease in power efficiency. In contrast, with this switching module, the capacitance of the first energy storage element is relatively small, so the unnecessary current can be reduced. Therefore, the decrease in power efficiency can be suppressed.

[0014] Specifically, the switching module comprises a positive-side main wire and a negative-side main wire connected to the positive and negative electrodes of the battery, a plurality of half-bridge circuits having an upper arm switching element and a lower arm switching element connected in series between the positive-side main wire and the negative-side main wire, starting from the positive-side main wire, and a plurality of output lines connected between the upper arm switching element and the lower arm switching element in each of the half-bridge circuits, wherein the conductor is in close contact with the input side electrode provided on the lower surface of each of the upper arm switching elements and the positive The conductive layer comprises a positive electrode conductor constituting the main electrode line, a negative electrode conductor connected to the output electrode of each of the lower arm switching elements and constituting the main negative electrode line, and an output conductor in close contact with the input electrode provided on the lower surface of each of the lower arm switching elements and constituting each of the output lines, wherein the conductive layer includes a plurality of positive electrode conductive layers connected to the positive electrode conductor and a plurality of negative electrode conductive layers connected to the negative electrode conductor, and the energy storage structure is provided by each of the positive electrode conductive layers and each of the negative electrode conductive layers facing each other via an electrical insulating layer.

[0015] The electrical insulating layer constituting the first energy storage element may be made of a material with a lower dielectric constant than the electrical insulating layers constituting the other energy storage elements.

[0016] In that case, the electrical insulating layer constituting the first energy storage element may be composed of at least one of aluminum oxide, aluminum nitride, and silicon nitride.

[0017] The electrical insulating layer constituting the first energy storage element may be configured with a greater thickness than the electrical insulating layers constituting the other energy storage elements. Furthermore, the uppermost conductive layer may be divided into two parts: a positive electrode side and a negative electrode side.

[0018] Furthermore, an internal conductor may be provided between the lower surface of the substrate and the lowest conductive layer, and an intermediate conductor may be interposed between the conductor and the plurality of conductive layers and the internal conductor, wherein the intermediate conductor includes a first intermediate conductor and a second intermediate conductor having greater electrical resistance than the first intermediate conductor, the internal conductor is connected to the conductor via the first intermediate conductor, and the plurality of conductive layers are connected to the conductor via the second intermediate conductor and the first intermediate conductor.

[0019] In either method, the capacitance of the first energy storage element can be reduced.

[0020] This specification also discloses another technology.

[0021] That is, the disclosed technology relates to a switching module in which switching control is performed, comprising a positive electrode side main line and a negative electrode side main line connected to each of the positive electrode and the negative electrode of a battery, a plurality of half-bridge circuits each having a switching element for an upper arm and a switching element for a lower arm connected in series in order from the side of the positive electrode side main line between the positive electrode side main line and the negative electrode side main line, and a plurality of output lines connected between the switching element for the upper arm and the switching element for the lower arm in each of the half-bridge circuits.

[0022] A positive electrode side conductor constituting the positive electrode side main line in close contact with an input side electrode provided on the lower surface of each of the switching elements for the upper arm, a negative electrode side conductor connected to an output side electrode of each of the switching elements for the lower arm and constituting the negative electrode side main line, an output conductor constituting each of the output lines in close contact with an input side electrode provided on the lower surface of each of the switching elements for the lower arm, and a substrate on which each of the positive electrode side conductor, the negative electrode side conductor, and the output conductor is in close contact with the upper surface and the lower surface is in close contact with a predetermined heat radiating member having conductivity.

[0023] The substrate includes a plurality of positive electrode side conductive layers connected to the positive electrode side conductor and a plurality of negative electrode side conductive layers connected to the negative electrode side conductor. Each of the positive electrode side conductive layers and each of the negative electrode side conductive layers face each other through an electrical insulation layer, whereby a power storage structure capable of accumulating charges interposed between the positive electrode side main line and the negative electrode side main line is provided inside the substrate.

[0024] Each of the switching elements for the upper arm and the switching elements for the lower arm are intensively arranged on the central side of the upper surface of the substrate, and the positive electrode side conductive layer and the negative electrode side conductive layer are composed of a plurality of frame-like structures provided on the outer edge portion of the substrate and at least one plate-like structure provided over the entire surface of the substrate.

[0025] According to this switching module, by configuring the conductive layer as a frame-shaped structure, it is possible to prevent a group of switching elements and the power storage structure from overlapping. As a result, the heat generated in the power storage structure and each switching element can be efficiently dissipated to the heat dissipation member.

[0026] On the other hand, if all of the conductive layer is configured as a frame-shaped structure, since a group of switching elements and the heat dissipation member face each other through the electrical insulation layer, a common mode current can flow. In contrast, according to this switching module, since the conductive layer includes at least one plate-shaped structure, the common mode current will flow across the plate-shaped structure, and the common mode current can be suppressed.

[0027] The above-described switching module is preferably applied to an inverter that is interposed between a battery and a motor and drives the motor with the power supplied from the battery.

[0028] That is, the inverter includes the above-described switching module and a DC link interposed between each of the positive-side main line and the negative-side main line and the battery. The DC link has a positive-side relay line interposed between the positive-side main line and the positive electrode side of the battery, a negative-side relay line interposed between the negative-side main line and the negative electrode side of the battery, and a smoothing capacitor installed between the positive-side relay line and the negative-side relay line. It is preferable to replace a part of the smoothing capacitor with the power storage structure.

[0029] If so, a large and expensive smoothing capacitor can be miniaturized, and the inverter can be made inexpensive.

[0030] The inverter also comprises the switching module described above and a DC link interposed between each of the positive terminal main line and the negative terminal main line and the battery, wherein the DC link has a positive terminal relay line interposed between the positive terminal main line and the positive terminal side of the battery, and a negative terminal relay line interposed between the negative terminal main line and the negative terminal side of the battery, and the smoothing capacitor installed in the DC link is omitted due to the substitution by the energy storage structure.

[0031] This would eliminate the need for smoothing capacitors, making the inverter even cheaper. [Effects of the Invention]

[0032] The disclosed technology enables the realization of higher-performance switching modules and inverters. [Brief explanation of the drawing]

[0033] [Figure 1A] For comparison, this is a diagram illustrating an inverter and switching module before applying the first disclosed technology. [Figure 1B] For comparison, this is a diagram illustrating a switching module before the application of the first disclosed technology. [Figure 1C] This is a schematic cross-sectional view along the arrow line A1-A1 in Figure 1B. [Figure 2] This is a simplified circuit diagram of the module to be improved. [Figure 3] This is a diagram illustrating the first improved module, which applies the first disclosed technology. [Figure 4] This is a diagram illustrating a second improved module that applies the first disclosed technology. [Figure 5] This is a diagram illustrating a third improved module that applies the first disclosed technology. [Figure 6] This is a diagram illustrating a fourth improved module that applies the first disclosed technology. [Figure 7A]For comparison, this is a diagram illustrating a switching module before the application of the second disclosed technology. [Figure 7B] This is a diagram illustrating a fifth improved module that applies the second disclosed technology. [Figure 8] This diagram shows the circuit configuration of the improved inverter with the improved module applied. [Modes for carrying out the invention]

[0034] The disclosed technologies are described below. Broadly speaking, there are two technologies (the first and second disclosed technologies) that correspond to the underlying technologies (see Patent Document 1 mentioned above). However, the following explanation is essentially illustrative.

[0035] -First Disclosure Technology- <Overview of the pre-improvement technology> The first disclosed technology relates to the second embodiment described in Patent Document 1. To facilitate understanding of the first disclosed technology, an inverter (improved inverter 1) and a switching module (improved module 20) before the application of the first disclosed technology will be described as comparative examples. Note that the improved module 20 corresponds to the second improved module 220 in Patent Document 1.

[0036] Figure 1A illustrates an improved inverter 1 for automotive use, equipped with the improved module 20. This improved inverter 1 is installed in hybrid or electric vehicles. The improved inverter 1 is positioned between the high-voltage battery 2, which is its power source, and the motor 3 that rotates the wheels.

[0037] The circuit of the improved module 20 consists of a positive terminal main line 21, a negative terminal main line 22, three half-bridge circuits 23, and three output lines 24. The positive terminal main line 21 is an electrical wire connected to the positive terminal side of the battery 2. The negative terminal main line 22 is an electrical wire connected to the negative terminal side of the battery 2.

[0038] Each half-bridge circuit 23 is provided in parallel between the positive terminal main line 21 and the negative terminal main line 22. Each half-bridge circuit 23 has two switching elements 30 (upper arm switching element 30U and lower arm switching element 30L). The switching elements 30 here are IGBTs. Note that IGBTs are just an example, and the switching elements 30 may be MOSFETs or the like.

[0039] The upper arm switching element 30U and the lower arm switching element 30L are connected in series in this order from the positive terminal main line 21. A freewheeling diode 25 is connected in antiparallel to each switching element 30. These half-bridge circuits 23 constitute an inverter circuit.

[0040] Each of the output lines 24 is connected to the portion of the half-bridge circuit 23 between the upper arm switching element 30U and the lower arm switching element 30L. These output lines 24 are connected to the motor 3.

[0041] The improved inverter 1 includes a control circuit (not shown) that performs switching control. The control circuit is connected to each switching element 30. The control circuit switches each switching element 30 on and off at a predetermined drive frequency (e.g., 10 kHz) by switching control. As a result, the DC power supplied from the battery 2 is converted into three-phase AC power consisting of U, V, and W, and supplied to the motor 3 via each output line 24.

[0042] The module 20 to be improved is connected to the battery 2 via a DC link 10. The DC link 10 is a circuit interposed between the positive terminal main line 21 and the negative terminal main line 22 and the battery 2.

[0043] The DC link 10 consists of a positive terminal relay wire 11 interposed between the positive terminal main wire 21 and the positive terminal of the battery 2, a negative terminal relay wire 12 interposed between the negative terminal main wire 22 and the negative terminal of the battery 2, and a smoothing capacitor 13 installed between the positive terminal relay wire 11 and the negative terminal relay wire 12.

[0044] The smoothing capacitor 13 is a large film capacitor. Specifically, a plastic film is used as its dielectric. This plastic film is then layered by winding or laminating it together with metal foil. In this way, the smoothing capacitor 13 is formed.

[0045] (Specific structure of the module to be improved) Figures 1B and 1C show the specific structure of the module 20 to be improved. Figure 1B is a schematic diagram of the inside of the module 20 to be improved, viewed from above. Figure 1C is a schematic cross-sectional view along the arrow line A1-A1 in Figure 1B.

[0046] The module 20 to be improved consists of a circuit board 40, a case cover 41, a heat sink 42 (heat dissipation member), and the like. Three half-bridge circuits 23, each consisting of six switching elements 30 (three upper arm switching elements 30U and three lower arm switching elements 30L), are provided on the circuit board 40.

[0047] The switching element 30 here is an IGBT, as described above. In the figure, "C" indicates the collector electrode 30a (input side electrode), "E" indicates the emitter electrode 30b (output side electrode), and "B" indicates the base electrode 30c (control electrode).

[0048] The collector electrode 30a, which is connected to the positive electrode side with a higher voltage, generates more heat than the emitter electrode 30b, which is connected to the negative electrode side with a lower voltage. The collector electrode 30a is provided across the entire lower surface of the switching element 30.

[0049] The emitter electrode 30b and base electrode 30c are provided on the upper surface of the switching element 30. The emitter electrode 30b has a larger area than the base electrode 30c, which is used for control. A freewheeling diode 25 is connected in antiparallel to each switching element 30 (see Figure 1), but it is not shown here.

[0050] The heat sink 42 is a metal component with excellent thermal conductivity and electrical conductivity. The heat sink 42 is formed in the shape of a rectangular plate, for example, using copper. The heat sink 42 is screwed to the vehicle-mounted cooler 43. The cooler 43 is preferably a water-cooled type in which cooling water flows inside.

[0051] The substrate 40 is formed in the shape of a rectangular plate. The material of the substrate 40 is mainly a material with excellent electrical insulation properties (high dielectric constant), as will be described later. In this embodiment, barium titanate is used as the material of the substrate 40. The substrate 40 is provided with a predetermined energy storage structure 63, which will be described later.

[0052] The lower surface of the circuit board 40 is in close contact with the upper surface of the heat sink 42. As a result, the circuit board 40 dissipates heat to the cooler 43 via the heat sink 42. The circuit board 40 is cooled by the heat sink 42.

[0053] The case cover 41 is made of plastic and is formed in a box shape with an open bottom. The case cover 41 is placed over the top surface of the heatsink 42. As a result, the perimeter of the circuit board 40 is covered by the case cover 41, and the circuit board 40 is protected by the case cover 41. The inside of the case cover 41 is filled with an electrically insulating resin.

[0054] A conductive material of a predetermined shape corresponding to electrical wiring is formed on the upper surface of the substrate 40. Specifically, the copper constituting the conductive material is bonded to the upper surface of the substrate 40 using a known DBC (Direct Bonded Copper) method.

[0055] Specifically, as shown in Figure 1B, the positive electrode conductor 51 constituting the positive electrode main line 21, the negative electrode conductor 52 constituting the negative electrode main line 22, the three output conductors 53 constituting each of the output lines 24 corresponding to the U, V, and W phases, and the six switching conductors 54 constituting the switching wiring connected to the base electrodes 30c of each switching element 30 are formed in close contact with the upper surface of the substrate 40.

[0056] Each of the positive electrode conductor 51, the negative electrode conductor 52, and the output conductor 53 is installed so as to extend parallel to the long side (first side 40a) of the substrate 40.

[0057] In detail, the positive electrode conductor 51 is installed so as to extend along one of its first sides 40a. The negative electrode conductor 52 is installed so as to extend along the other first side 40a. Each of the output conductors 53 is installed so as to extend between the positive electrode conductor 51 and the negative electrode conductor 52.

[0058] The positive electrode conductor 51 has a first extended portion 51a that extends in a strip shape along adjacent first sides 40a, and three first element junction portions 51b that extend from the inner edge of the first extended portion 51a at intervals to the central part of the substrate 40. The negative electrode conductor 52 has a second extended portion 52a that extends in a strip shape along adjacent first sides 40a.

[0059] The positive electrode conductor 51 further includes, in addition to the first extended portion 51a and the first element junction portion 51b, four first outer protrusions 51c that extend toward adjacent first sides 40a at a distance from the outer edge of the first extended portion 51a, and a first side end portion 51d that extends in contact with the end face of the first side 40a, while being connected to the tip of each first outer protrusion 51c.

[0060] The negative electrode conductor 52 further has, in addition to the second extended portion 52a, four second outer protrusions 52b that extend toward the adjacent first side 40a at a distance from the outer edge of the second extended portion 52a, and a second side end portion 52c that extends in contact with the end face of the first side 40a, while being connected to the tip of each second outer protrusion 52b.

[0061] Each output conductor 53 has a third extension portion 53a that extends in a strip shape parallel to the first side 40a, and a third element junction portion 53b provided at one end of the third extension portion 53a. Each third element junction portion 53b is aligned in the central part of the substrate 40 parallel to the first side 40a, and each third extension portion 53a is formed to a length corresponding to its arrangement.

[0062] Each of the first extension portion 51a, the second extension portion 52a, and the third extension portion 53a extends outward from one of the short sides (second side 40b) of the substrate 40. As a result, one end of each of these protrudes from the substrate 40 and forms a connection terminal.

[0063] Each of the switching conductors 54 is installed along the first side 40a of the substrate 40, with three units spaced apart at each edge.

[0064] Each upper arm switching element 30U has its lower surface soldered onto the first element junction 51b of the positive electrode side conductor 51. As a result, the collector electrode 30a of each upper arm switching element 30U is connected to the positive electrode side main line 21.

[0065] The emitter electrode 30b of each upper arm switching element 30U is connected to the output conductor 53 of each phase via a first bonding wire 55a. As a result, the emitter electrode 30b of each upper arm switching element 30U is connected to the output line 24. The base electrode 30c of each upper arm switching element 30U is connected to the switching conductor 54 via a second bonding wire 55b.

[0066] Each lower arm switching element 30L has its lower surface soldered onto the third element junction 53b of the output conductor 53 for each phase. As a result, the collector electrode 30a of each lower arm switching element 30L is connected to the output line 24 for each phase.

[0067] The emitter electrode 30b of each lower arm switching element 30L is connected to the negative electrode conductor 52 via a third bonding wire 55c. As a result, the collector electrode 30a of each lower arm switching element 30L is connected to the negative electrode main line 22.

[0068] The base electrode 30c of each lower arm switching element 30L is connected to each switching conductor 54 via a fourth bonding wire 55d. Each switching conductor 54 is provided to switch the current path between the collector electrode 30a and the emitter electrode 30b on and off.

[0069] As described above, the group of first element junction 51b and third element junction 53b is located in the central part of the substrate 40. As a result, the upper arm switching element 30U and the lower arm switching element 30L are concentrated in the central part of the upper surface of the substrate 40.

[0070] (Electricity storage structure) The improved module 20 differs from conventional switching modules in that a predetermined energy storage structure 63 is provided on the circuit board 40.

[0071] In other words, the substrate 40 includes a plurality of electrical insulating layers 60 made of the same material, and a plurality of conductive layers (a plurality of positive electrode side conductive layers 61 connected to the positive electrode side conductor 51, and a plurality of negative electrode side conductive layers 62 connected to the negative electrode side conductor 52). The number of each positive electrode side conductive layer 61 and negative electrode side conductive layer 62 is determined by the specifications. In the case of this substrate 40, the positive electrode side conductive layer 61 consists of 2 layers, and the negative electrode side conductive layer 62 consists of 3 layers.

[0072] Furthermore, each of these positive electrode conductive layers 61 and each of the negative electrode conductive layers 62 are facing each other via an electrical insulating layer 60. In this way, a power storage structure 63 is provided inside the substrate 40 that can store charge interposed between the positive electrode main wire 21 and the negative electrode main wire 22.

[0073] Specifically, the positive electrode conductive layer 61 and the negative electrode conductive layer 62 are each formed as a rectangular thin film having approximately the same size as the substrate 40. Furthermore, the positive electrode conductive layer 61 and the negative electrode conductive layer 62 are provided over the entire surface of the substrate 40.

[0074] The size of the short side of each of the positive electrode conductive layer 61 and the negative electrode conductive layer 62 is slightly smaller than the size of the short side (second side 40b) of the substrate 40. As a result, the tip of each positive electrode conductive layer 61 is located with a gap between it and the other end face of the first side 40a. The tip of each negative electrode conductive layer 62 is located with a gap between it and one end face of the first side 40a.

[0075] As shown in an enlarged view in Figure 1C, each positive electrode conductive layer 61 is connected to a positive electrode conductive end 65 provided on one end face of the first side 40a. Each negative electrode conductive layer 62 is connected to a negative electrode conductive end 66 provided on the other end face of the first side 40a. The positive electrode conductive end 65 is joined to the first side end 51d by soldering. The negative electrode conductive end 66 is joined to the second side end 52c by soldering.

[0076] Each of these positive electrode conductive layer 61 and negative electrode conductive layer 62 is formed to extend alternately parallel to the upper and lower surfaces of the substrate 40. Specifically, the substrate 40 is constructed by stacking the following layers in this order: electrical insulating layer 60, negative electrode conductive layer 62 (corresponding to the uppermost conductive layer: CL1), electrical insulating layer 60, positive electrode conductive layer 61 (CL2), electrical insulating layer 60, negative electrode conductive layer 62 (CL3), electrical insulating layer 60, positive electrode conductive layer 61 (CL4), electrical insulating layer 60, negative electrode conductive layer 62 (corresponding to the lowest conductive layer: CL5), and electrical insulating layer 60.

[0077] As a result, the energy storage structure 63 is composed of multiple stacked energy storage elements, as shown in an enlarged view in Figure 1C. Specifically, in this embodiment, the first energy storage element CE1 is composed of a conductor 53 formed on the upper surface of the substrate 40, a negative electrode side conductive layer CL1 below it, and an electrical insulating layer 60 interposed between them. Similarly, the second energy storage element CE2 is composed of a negative electrode side conductive layer CL1, a positive electrode side conductive layer CL2 below it, and an electrical insulating layer 60 interposed between them.

[0078] The third energy storage element CE3 is composed of a positive electrode conductive layer CL2, a negative electrode conductive layer CL3 below it, and an electrical insulating layer 60 interposed between them. The fourth energy storage element CE4 is composed of a negative electrode conductive layer CL3, a positive electrode conductive layer CL4 below it, and an electrical insulating layer 60 interposed between them. The fifth energy storage element CE5 is composed of a positive electrode conductive layer CL4, a negative electrode conductive layer CL5 below it, and an electrical insulating layer 60 interposed between them. The sixth energy storage element CE6 is composed of a negative electrode conductive layer CL5, a heat sink 42 in close contact with the lower surface of the substrate 40, and an electrical insulating layer 60 interposed between them.

[0079] Each of the energy storage elements CE1 to CE6 has a predetermined capacitance. When these energy storage elements CE1 to CE6 are assembled, an energy storage structure 63 is formed that functions as a smoothing capacitor.

[0080] In particular, in the case of this improved module 20, such an energy storage structure 63 is interposed between most of the output conductors 53, including the midpoint 56 where each input electrode of the lower arm switching element 30L is installed, and the heat sink 42. This prevents common-mode current from flowing and prevents the generation of common-mode noise.

[0081] In other words, when switching control is performed, each switching element 30 is turned on and off at a predetermined timing. Consequently, the voltage at the midpoint 56 where the input electrodes of each output conductor 53, particularly the lower arm switching element 30L, are installed changes significantly and periodically. As a result, in a conventional structure without an energy storage structure 63, common-mode current flows and common-mode noise is generated.

[0082] In contrast, in the case of the improved module 20, as described above, a first energy storage element CE1 is formed as a virtual capacitor between the negative electrode side conductive layer 62 (CL1), which is located at the top of the substrate 40, and each output conductor 53. Furthermore, a sixth energy storage element CE6 is formed as a virtual capacitor between the negative electrode side conductive layer 62 (CL5), which is located at the bottom of the substrate 40, and the heat sink 42.

[0083] As a result, even when switching control is performed, the midpoint 56, where the voltage change is large, is opposite the negative electrode side conductive layer 62 and the electrical insulating layer 60, which do not change in potential, so no charge is accumulated in the sixth energy storage element CE6.

[0084] No current flows through the path from the first energy storage element CE1 to the sixth energy storage element CE6. The common-mode current value is zero. Therefore, with this improved inverter 1, common-mode noise can be almost completely eliminated.

[0085] <Problems with the pre-improvement technology and their solutions> The improved inverter 1 and improved module 20 described above had a problem in that unnecessary current flowed due to the first energy storage element CE1, which reduced power efficiency.

[0086] Figure 2 shows a simplified circuit diagram of the improved module 20, along with the first energy storage element CE1.

[0087] As shown in the upper part of Figure 2, for example, when the switching element 30U for the upper arm of the U phase is turned on (the switching element 30L for the lower arm of the U phase is turned off), current flows as indicated by the dashed arrow BL1 and is supplied to the motor through the output line 24 of the U phase. Consequently, current also flows to the first energy storage element CE1 as indicated by the dashed arrow BL2, and the first energy storage element CE1 is charged.

[0088] When the U-phase lower arm switching element 30L is turned on (and the U-phase upper arm switching element 30U is turned off), discharge occurs from the first energy storage element CE1, and current flows between the U-phase lower arm switching element 30L and the first energy storage element CE1, as shown by the dashed arrow BL3 in the lower diagram of Figure 2. In the V-phase and W-phase half-bridge circuit 23, current flows similarly when the lower arm switching element 30L is switched on and off, only the phase is shifted.

[0089] The current used to store energy in the first energy storage element CE1, and the subsequent discharged current, do not contribute to the motor's operation. In other words, they are unnecessary currents. These currents reduce power efficiency.

[0090] In response, the inventors considered that by reducing the capacitance of the first energy storage element CE1, it would be possible to reduce this unwanted current while ensuring the overall capacitance of the energy storage structure 63. That is, the capacitance of the first energy storage element CE1 is configured to be smaller than the capacitance of the other energy storage elements.

[0091] This reduces the amount of energy that can be stored in the first energy storage element CE1, and consequently, the amount of discharged current also decreases. On the other hand, the amount of energy stored in the second energy storage element CE2, etc., can be maintained. Therefore, the overall capacitance of the energy storage structure 63 can be secured. The capacitance C is calculated by the following formula.

[0092]

number

[0093] ε0 is a constant. εs is the relative permittivity of the insulating material between the electrodes. S is the area of ​​the electrodes. d is the distance between the electrodes.

[0094] Therefore, reducing the relative permittivity reduces the capacitance C. Reducing the electrode area reduces the capacitance C. Increasing the distance between electrodes reduces the capacitance C.

[0095] The disclosed technology is based on this idea. Below, we will specifically describe a switching module (improved module) to which the first disclosed technology has been applied to the improved module 20.

[0096] <First Improvement Module> Figure 3 shows the main components of the first improved module 120A. The basic configuration of the first improved module 120A is the same as that of the module 20 to be improved. Therefore, we will explain in detail the differences from the module 20 to be improved, and other components will be simplified or omitted (the same applies to the other improved modules 120B to 120E).

[0097] In the case of the first improved module 120A, in order to reduce the capacitance C of the first energy storage element CE1, the electrical insulating layer 60 constituting the first energy storage element CE1 is made of a material with a lower dielectric constant than the electrical insulating layers 60 constituting the other energy storage elements CE2 to CE6.

[0098] The substrate of the first improved module 120A (an improved version of substrate 40, improved substrate 140) uses two different materials. As mentioned above, the substrate 40 of the improved module 20 uses barium titanate, which has a high dielectric constant (approximately 3500), as one of its materials. In contrast, the improved substrate 140 uses a material with a dielectric constant significantly lower than barium titanate for the electrical insulating layer 60 of the first energy storage element CE1.

[0099] In other words, a layer with a lower dielectric constant than conventional materials (low dielectric constant layer 60A) is formed on the surface of the improved substrate 140. The material for the low dielectric constant layer 60A can be aluminum oxide, aluminum nitride, or silicon nitride. The dielectric constants of these materials are 10 or less, which is sufficiently low. Therefore, it is effective in reducing capacitance C.

[0100] Among these, aluminum nitride is particularly preferred. Aluminum nitride has a relatively high thermal conductivity. Therefore, aluminum nitride also has excellent heat dissipation properties.

[0101] <Second Improvement Module> Figure 4 shows the main components of the second improved module 120B. In the case of the second improved module 120B, in order to reduce the capacitance C of the first energy storage element CE1, the electrical insulating layer 60 constituting the first energy storage element CE1 is made with a greater thickness than the electrical insulating layers 60 constituting the other energy storage elements CE2 to CE6.

[0102] The improved substrate 140 of the second improved module 120B uses a single material, such as barium titanate, similar to the improved module 20. Furthermore, the thickness t1 of the electrical insulating layer 60 constituting the first energy storage element CE1 is greater than the thickness t2 of the electrical insulating layer 60 constituting the other energy storage elements CE2 to CE6.

[0103] For example, the thickness of the electrical insulating layer 60 on the surface of the energy storage structure 63 of the module 20 to be improved may be increased. In this case, the thickness of the improved substrate 140 will increase. Alternatively, the thickness of the electrical insulating layer 60 of the other energy storage elements CE2 to CE6 of the energy storage structure 63 may be relatively reduced, and the reduction in thickness may be used to increase the thickness of the electrical insulating layer 60 on the surface of those elements. In this case, the thickness of the substrate 40 can be maintained. The thickness may also be adjusted by combining both of these methods.

[0104] <Third Improvement Module> Figure 5 shows the main components of the third improved module 120C. In the case of the third improved module 120C, the uppermost conductive layer CL1 is divided into positive and negative electrode sides in order to reduce the capacitance C of the first energy storage element CE1. This corresponds to a means of reducing the electrode area.

[0105] As shown in Figure 5, the uppermost conductive layer CL1 of the improved substrate 140 (corresponding to the negative electrode side conductive layer 62 of the substrate 40) is divided into two parts approximately in the middle between the positive electrode side and the negative electrode side, so as not to conduct electricity with each other. The positive electrode side portion is connected to the positive electrode. In other words, the uppermost conductive layer CL1 in the third improved module 120C is composed of a negative electrode side semiconducting layer 62a and a positive electrode side semiconducting layer 61a.

[0106] Specifically, the negative electrode semiconducting layer 62a is connected to the negative electrode conductive end 66. The positive electrode semiconducting layer 61a is connected to the positive electrode conductive end 65. The negative electrode semiconducting layer 62a and the positive electrode semiconducting layer 61a have approximately the same surface area, and their protruding edges face each other separated by a small gap (slit G).

[0107] Furthermore, the point of division does not necessarily have to be approximately in the center between the positive and negative electrode sides. The surface areas of the negative electrode semiconducting layer 62a and the positive electrode semiconducting layer 61a may be different. In particular, it is preferable to make the area of ​​the part facing most of each output conductor 53 approximately half.

[0108] <Fourth Improvement Module> Figure 6 shows the main components of the fourth improved module 120D. In the case of the fourth improved module 120D, the structure of the conductor and other components corresponding to the topmost conductive layer was devised in order to reduce the capacitance C of the first energy storage element CE1.

[0109] The fourth improved module 120D in the example is an improvement over the module 20 to be improved. Specifically, as shown in Figure 6, the top conductive layer CL1 of the improved substrate 140 is the negative electrode side conductive layer 62. Therefore, in the fourth improved module 120D, the structure of the negative electrode side conductor 52 and the like is changed. An internal second end portion 52d, an internal conductor 52e, and the like are newly added to the negative electrode side conductor 52.

[0110] The internal second side end 52d is provided along the side end face of the substrate 40. As a result, the internal second side end 52d is connected to multiple negative electrode conductive layers 62. The internal second side end 52d has a higher electrical resistance than the second side end 52c. That is, as described above, the second side end 52c is made of copper, which has low electrical resistance. In contrast, the internal second side end 52d is made of a metal with higher electrical resistance, such as nickel.

[0111] A second outer projection 52b and a second side end 52c are provided outside the internal second side end 52d, via a shielding insulating layer 60a. The internal second side end 52d and the second outer projection 52b and second side end 52c are electrically insulated from each other.

[0112] Furthermore, an internal conductor 52e is provided between the lower surface of the improved substrate 140 and the lowest conductive layer CL5. That is, a plate-shaped conductor extending over substantially the entire surface of the improved substrate 140 is provided between the lower surface of the improved substrate 140 and the lowest conductive layer CL5. This conductor constitutes the internal conductor 52e. The internal conductor 52e is connected to the second side end 52c, penetrating the internal second side end 52d. The internal conductor 52e is joined to the internal second side end 52d so as to be electrically connected.

[0113] As a result, a second side end 52c and an internal second side end 52d are interposed between the negative electrode side conductor 52 located on the upper surface of the improved substrate 140 and the plurality of negative electrode side conductive layers 62. The internal conductor 52e is connected to the negative electrode side conductor 52 located on the upper surface of the improved substrate 140 via the second side end 52c, and the plurality of negative electrode side conductive layers 62 are connected to the negative electrode side conductor 52 located on the upper surface of the improved substrate 140 via the second side end 52c and the internal second side end 52d.

[0114] The second side end 52c and the internal second side end 52d correspond to "relay conductors". The second side end 52c corresponds to the "first relay conductor", and the internal second side end 52d corresponds to the "second relay conductor".

[0115] The current flowing through the first energy storage element CE1 flows through the negative electrode conductor 52 in the order of the internal second end 52d, the internal conductor 52e, and the second end 52c, as shown by the dashed arrow BL4 in Figure 6. At this time, the internal second end 52d has electrical resistance R1···Rn. The amount of current is limited by these resistances.

[0116] Furthermore, as shown by the dashed arrow BL5 in Figure 6, the common-mode current flows through the intrinsic conductor 52e, and is therefore interrupted by the intrinsic conductor 52e. Consequently, the outflow of common-mode current can be prevented.

[0117] -Second Disclosure Technology- The second disclosed technology relates to the first embodiment described in Patent Document 1. To facilitate understanding of the second disclosed technology, a switching module (second improved module 20B) before the application of the second disclosed technology will be described as a comparative example. Note that the second improved module 20B corresponds to the improved module 120 in Patent Document 1.

[0118] Figure 7A shows the characteristic configuration of the second improved module 20B. The energy storage structure 63 of the second improved module 20B differs from the energy storage structure 63 of the improved module 20 in that each of the positive electrode side conductive layer 61 and the negative electrode side conductive layer 62 has a rectangular opening 64 in its center. In other words, each of the positive electrode side conductive layer 61 and the negative electrode side conductive layer 62 of the second improved module 20B corresponds to a "frame-like structure" provided on the outer edge of the substrate 40.

[0119] This configuration prevents the group of switching elements 30 and the energy storage structure 63 from overlapping. Consequently, when switching control is performed, heat is generated in both the energy storage structure 63 and each of the switching elements 30, but the heat from both can be efficiently transferred to the heat sink 42 for heat dissipation.

[0120] However, in this configuration, the group of switching elements 30 and the heat sink 42 face each other via an electrical insulating layer 60, so there is a power storage element (through-hole power storage element) that communicates with them through the opening 64. Common-mode current can flow through the through-hole power storage element.

[0121] Therefore, in order to resolve this issue without significantly impairing heat dissipation, the switching module (fifth improved module 120E) to which the second disclosed technology is applied includes, as shown in Figure 7B, at least one plate-like structure 70 provided over the entire surface of the improved substrate 140, in the energy storage structure 63.

[0122] The plate-shaped structure 70 corresponds to the positive electrode side conductive layer 61 or the negative electrode side conductive layer 62 of the improved module 20 and each of the improved modules 120A to 120D described above. The plate-shaped structure 70 is preferably placed approximately in the center of the stacking direction of the energy storage structure 63, but it may be off-center to some extent. In addition, one plate-shaped structure 70 is sufficient, but multiple plates may be used.

[0123] According to the fifth improved module 120E, the common-mode current flows across the plate-like structure 70, thus suppressing the common-mode current.

[0124] <Improved Inverter> Figure 8 shows an example of the circuit configuration of the improved inverter 100 to which any of the first to fifth improved modules 120A to 120E described above is applied.

[0125] The energy storage structure 63, that is, a group of positive electrode conductive layers 61 and negative electrode conductive layers 62 facing each other via an electrical insulating layer 60, functions as a virtual capacitor Ci that can replace the smoothing capacitor 13 in the circuits of the improved modules 120A to 120E.

[0126] The virtual capacitor Ci corresponds to a group of energy storage elements connected to both the positive and negative terminal ends of each half-bridge circuit 23 in the improved modules 120A to 120E. In other words, the virtual capacitor Ci is connected in parallel with the smoothing capacitor 13 in the circuit of the improved inverter 100, and the energy storage structure 63 of the substrate 40 performs the same function as the smoothing capacitor 13.

[0127] Therefore, as shown in the upper part of Figure 8, the smoothing capacitor 13 can be miniaturized, and part of it can be replaced by the energy storage structure 63. Furthermore, as shown in the lower part of Figure 8, if the energy storage structure 63 performs all the functions of the smoothing capacitor 13, the smoothing capacitor 13 can be omitted. As a result, the cost of the inverter can be reduced.

[0128] Furthermore, the disclosed technology is not limited to the embodiments described above, but also includes various other configurations. For example, the configurations of the improved modules 120A to 120E described above may be combined as appropriate. [Explanation of Symbols]

[0129] 1. Inverters subject to improvement 2 batteries 3 motors 10 DC Links 11 Positive side relay wire 12. Negative electrode relay line 13. Smoothing Capacitor 20 modules to be improved 21 Positive side main line 22 Negative side main line 23 Half-bridge circuit 24 output lines 25 Freewheeling Diode 30 Switching elements 30a Collector electrode (input side electrode) 30b Emitter electrode (output side electrode) 30c base electrode (control electrode) 30U Switching element for upper arm 30L Lower Arm Switching Element 40 circuit boards 41 Case Cover 42 Heat sink (heat dissipation component) 43 Cooler 51 Positive electrode conductor 51a 1st extension part 51b Junction of the first element 51c 1st outer overhang 51d 1st side end 52 Negative electrode conductor 52a 2nd extension part 52b Second outer overhang 52c Second side end 52d Internal second side end 52e Intrinsic conductor 53 Output conductor 53a 3rd extension part 53b Third element junction 54 Switching conductor 60 Electrical insulation layer 60a Shielding Insulation Layer 61 Positive electrode side conductive layer 61a Positive electrode side semiconducting layer 62 Negative electrode side conductive layer 62a Negative electrode side semiconducting layer 63 Energy storage structure 64 openings 65 Positive side conductive terminal 66 Negative electrode conductive end 70 Plate-like structure 100 Improved Inverter 120 Improved Modules 140 Improved Circuit Board

Claims

1. A switching module comprising a substrate having a conductive material formed on its upper surface for connecting multiple switching elements, and the lower surface of the substrate being in close contact with a predetermined heat dissipation member having conductivity, The substrate includes a plurality of conductive layers connected to the conductor, Each of the conductive layers faces the other via an electrical insulating layer, thereby providing a power storage structure within the substrate composed of a plurality of stacked power storage elements. A switching module in which the capacitance of a first energy storage element, which is composed of the conductor and the uppermost conductive layer, is configured to be smaller than the capacitance of the other energy storage elements.

2. In the switching module according to claim 1, The device comprises a positive-side main wire and a negative-side main wire connected to the positive and negative electrodes of a battery, a plurality of half-bridge circuits having an upper arm switching element and a lower arm switching element connected in series between the positive-side main wire and the negative-side main wire, starting from the positive-side main wire, and a plurality of output lines connected between the upper arm switching element and the lower arm switching element in each of the half-bridge circuits. The aforementioned conductor is A positive electrode side conductor is provided on the lower surface of each of the upper arm switching elements, in close contact with the input side electrode and constituting the positive electrode side main line, The negative electrode side conductor, which is connected to each output side electrode of the lower arm switching element and constitutes the negative electrode side main line, An output conductor is provided in close contact with the input side electrode located on the lower surface of each of the lower arm switching elements, and each of the output lines is formed by an output conductor, It has, The conductive layer is A plurality of positive electrode side conductive layers connected to the positive electrode side conductor, A plurality of negative electrode side conductive layers connected to the negative electrode side conductor, Includes, A switching module in which the energy storage structure is provided by each of the positive electrode conductive layers and each of the negative electrode conductive layers facing each other via an electrical insulating layer.

3. In the switching module according to claim 1, A switching module in which the electrical insulating layer constituting the first energy storage element is made of a material with a lower dielectric constant than the electrical insulating layers constituting the other energy storage elements.

4. In the switching module according to claim 2, A switching module in which the electrical insulating layer constituting the first energy storage element is made of at least one of aluminum oxide, aluminum nitride, and silicon nitride.

5. In the switching module according to claim 1, A switching module in which the electrical insulating layer constituting the first energy storage element is configured to have a greater thickness than the electrical insulating layers constituting the other energy storage elements.

6. In the switching module according to claim 1, A switching module in which the uppermost conductive layer is divided into two parts, one for the positive electrode side and one for the negative electrode side.

7. In the switching module according to claim 1, An intrinsic conductor is provided between the lower surface of the substrate and the lowest conductive layer. A relay conductor is interposed between the conductor, the plurality of conductive layers, and the intrinsic conductor. The relay conductor includes a first relay conductor and a second relay conductor having a higher electrical resistance than the first relay conductor. A switching module in which the intrinsic conductor is connected to the conductor via the first relay conductor, and a plurality of the conductive layers are connected to the conductor via the second relay conductor and the first relay conductor.

8. A switching module comprising a positive-side main wire and a negative-side main wire connected to the positive and negative electrodes of a battery, a plurality of half-bridge circuits having an upper arm switching element and a lower arm switching element connected in series between the positive-side main wire and the negative-side main wire, starting from the positive-side main wire, and a plurality of output lines connected between the upper arm switching element and the lower arm switching element in each of the half-bridge circuits, wherein switching control is performed, A positive electrode side conductor is provided on the lower surface of each of the upper arm switching elements, in close contact with the input side electrode and constituting the positive electrode side main line, The negative electrode side conductor, which is connected to each output side electrode of the lower arm switching element and constitutes the negative electrode side main line, An output conductor is provided in close contact with the input side electrode located on the lower surface of each of the lower arm switching elements, and each of the output lines is formed by an output conductor, The positive electrode conductor, the negative electrode conductor, and the output conductor are each in close contact with the upper surface of a substrate, and the lower surface is in close contact with a predetermined heat dissipation member having conductivity, Equipped with, The aforementioned substrate, A plurality of positive electrode side conductive layers connected to the positive electrode side conductor, A plurality of negative electrode side conductive layers connected to the negative electrode side conductor, Includes, Each of the positive electrode conductive layers and each of the negative electrode conductive layers are facing each other via an electrical insulating layer, thereby providing an energy storage structure within the substrate that allows for the accumulation of charge interposed between the positive electrode main wire and the negative electrode main wire. The upper arm switching element and the lower arm switching element are each arranged in a concentrated manner towards the center of the upper surface of the substrate. The positive electrode side conductive layer and the negative electrode side conductive layer A plurality of frame-shaped structures provided on the outer edge portion of the substrate, At least one plate-like structure provided over the entire surface of the substrate, A switching module composed of the following components.

9. An inverter interposed between a battery and a motor, which drives the motor with power supplied from the battery, A switching module according to claim 2 or claim 8, A DC link is interposed between each of the positive and negative main wires and the battery, Equipped with, The aforementioned DC link A positive electrode relay wire interposed between the positive electrode main wire and the positive electrode side of the battery, A negative electrode relay wire interposed between the negative electrode main wire and the negative electrode side of the battery, A smoothing capacitor is installed between the positive electrode relay line and the negative electrode relay line, It has, An inverter in which a portion of the smoothing capacitor is replaced by the energy storage structure.

10. An inverter interposed between a battery and a motor, which drives the motor with power supplied from the battery, A switching module according to claim 2 or claim 8, A DC link is interposed between each of the positive and negative main wires and the battery, Equipped with, The aforementioned DC link A positive electrode relay wire interposed between the positive electrode main wire and the positive electrode side of the battery, A negative electrode relay wire interposed between the negative electrode main wire and the negative electrode side of the battery, It has, An inverter in which the smoothing capacitor installed in the DC link is omitted due to the substitution of the aforementioned energy storage structure.

Images