Power conversion device

Abstract

A power conversion device (1) comprises: a substrate (8) provided with a filter circuit component (9) having one or a plurality of capacitors for removing noise; a power module (7) having a power semiconductor element (7a); and main circuit wiring connected to the power module (7). At least a portion of the main circuit wiring comprises a bus bar (30). The bus bar (30) has a main bus bar (11) constituting the main circuit wiring, and a branching bus bar (12) that branches off from the main bus bar (11). The branching bus bar (12) is electrically connected to the substrate (8).

Description

Power Conversion Device

[0001] The present disclosure relates to a power conversion device.

[0002] Electrically powered vehicles using a motor as a drive source, such as hybrid vehicles, plug-in hybrid vehicles, electric vehicles, and fuel cell vehicles, are equipped with power conversion devices such as inverters for driving the drive motor and converters for stepping up and down the power supply voltage of a battery. These power conversion devices generally contain switching circuits, such as chopper circuits and bridge circuits, that generate a lot of high-frequency noise. To combat noise from the switching circuits, various filter circuits and shielding structures are used in power conversion devices. In recent years, there has been a trend toward reducing the cost, weight to improve fuel efficiency, and size to reduce installation space.

[0003] A power supply device configuration that can supply power to an external device while reducing the effects of leakage magnetic flux from a transformer and reducing costs has been disclosed (see, for example, Patent Document 1). Also, a power conversion device configuration that can efficiently cool a noise reduction capacitor and a noise reduction core while satisfying the demand for miniaturization of the power conversion device has been disclosed (see, for example, Patent Document 2).

[0004] In the configuration disclosed in Patent Document 1, a power supply device has a first shielding section disposed between a transformer and a filter mechanism, and a second shielding section disposed between a filter section having components mounted on a circuit board that functions to reduce AC components contained in DC power, which constitute the filter mechanism, and an output stabilization section having components mounted on a circuit board that functions to stabilize and output DC power with reduced AC components. Power is supplied to each shielding section in this order through connecting wires. The shielding sections prevent noise, including leakage flux, from being superimposed on each other between the transformer, filter section, and output stabilization section.

[0005] In the configuration disclosed in Patent Document 2, a power conversion device includes a first thermally conductive partition wall provided between the noise reduction capacitor and the noise reduction core and between the first smoothing capacitor section and the second smoothing capacitor section, a second thermally conductive partition wall provided between the filter circuit section and the smoothing capacitor, a first DC bus bar connecting a DC power supply terminal, the noise reduction capacitor, and the noise reduction core to transmit power, and a second DC bus bar connecting the first DC bus bar through which the noise reduction core passes, the smoothing capacitor, and the power semiconductor circuit to transmit power. The power conversion device is configured so that the noise reduction capacitor, the noise reduction core, and the smoothing capacitor are wired in this order via the first DC bus bar and the second DC bus bar, and power is supplied to the power conversion device. Each bus bar is thermally connected to and cooled by a thermally conductive member, and the respective partition walls are cooled. A shield portion formed in the second partition wall prevents noise current from the smoothing capacitor and the power semiconductor module from leaking to the DC power supply terminal.

[0006] Patent No. 5516999 Patent No. 7319945

[0007] In the above-mentioned Patent Document 1, the provision of a shielding portion reduces the effects of leakage magnetic flux. However, because the transformer constituting the main circuit and the filter mechanism constituting the noise-removing filter circuit and mounted on the circuit board are arranged side by side on the same plane and electrically connected in series, the main circuit wiring is long due to the electrical connection wiring with the filter. The longer main circuit wiring increases wiring loss and heat generation, causing the components constituting the filter circuit, such as capacitors and circuit boards, to exceed their maximum operating temperatures. Furthermore, the provision of multiple shielding portions, which act as partitions, restricts the layout and creates wasted space, resulting in an increase in the size of the device.

[0008] In the above-mentioned Patent Document 2, the noise reduction capacitor and the noise reduction core can be efficiently cooled. However, since the filter circuit section formed by the noise reduction capacitor and the noise reduction core is wired with a bus bar, and the bus bar is in contact with a partition wall between the filter section and the smoothing capacitor section via a thermally conductive member to dissipate heat, there is a problem similar to the problem in Patent Document 1, in that the provision of the partition wall restricts the layout and creates wasted space, resulting in an increase in the size of the device. In addition, there is a problem in that the addition of a cooling member for the bus bar increases the number of assembly steps and increases costs.

[0009] Therefore, an object of the present disclosure is to obtain a power conversion device that has a reduced main circuit wiring, low loss, low cost, and small size.

[0010] The power conversion device of the present disclosure includes a substrate provided with a filter circuit component having one or more capacitors that remove noise, a power module having power semiconductor elements, and main circuit wiring connected to the power module, at least a portion of the main circuit wiring consisting of bus bars, the bus bars including a main bus bar that constitutes the main circuit wiring and branch bus bars branching from the main bus bar, and the branch bus bars are electrically connected to the substrate.

[0011] According to the power conversion device of the present disclosure, the power conversion device includes a substrate provided with filter circuit components, a power module, and main circuit wiring connected to the power module, wherein at least a portion of the main circuit wiring is formed by a busbar, the busbar including a main busbar constituting the main circuit wiring and a branch busbar branching from the main busbar. The branch busbar is electrically connected to the substrate, and the busbar electrically connected to the power module is branched and connected to the substrate provided with the filter circuit components through the branch busbar. This allows the length of the main busbar to be shortened without routing the main busbar through which a large current flows, thereby reducing loss in the busbar and suppressing heat generation in the busbar. The reduced loss in the busbar allows the power conversion device to be reduced. Furthermore, since no components for cooling the busbar are required, layout constraints for cooling are eliminated, thereby allowing the power conversion device to be miniaturized. Furthermore, the absence of components for cooling the busbar allows the power conversion device to be manufactured at a lower cost.

[0012] 11 is a diagram illustrating a configuration of a power conversion device according to a first embodiment. It is a plan view showing an outline of a power conversion device according to the first embodiment. It is a cross-sectional view of the power conversion device taken along the A-A cross section of FIG. 2. It is a cross-sectional view of the power conversion device taken along the B-B cross section of FIG. 2. It is a cross-sectional view of the power conversion device taken along the C-C cross section of FIG. 2. It is a cross-sectional view of another power conversion device taken along the B-B cross section of FIG. 2. It is a plan view showing a main part of a power conversion device according to a second embodiment. It is a cross-sectional view of a main part of a power conversion device taken along the D-D cross section of FIG. 7. It is a cross-sectional view of a main part of a power conversion device taken along the E-E cross section of FIG. 7. It is a plan view showing a main part of another power conversion device according to the second embodiment. It is a cross-sectional view of a main part of another power conversion device taken along the F-F cross section of FIG. 11. It is a plan view showing a main part of another power conversion device according to the second embodiment. It is a cross-sectional view of a main part of another power conversion device taken along the G-G cross section of FIG. 13. It is a plan view showing an outline of a power conversion device according to a third embodiment. 16 is a cross-sectional view of the power converter taken along the line HH in FIG. 15.

[0013] Hereinafter, a power conversion device according to an embodiment of the present disclosure will be described with reference to the drawings. Note that the same or equivalent members and parts in each drawing will be denoted by the same reference numerals.

[0014] Embodiment 1. Fig. 1 is a block diagram showing the configuration of a power conversion device 1 according to embodiment 1, Fig. 2 is a plan view showing an outline of the power conversion device 1, and is a diagram showing the component arrangement with cover 18 removed from power conversion device 1 and only the outline of board 8 being shown, Fig. 3 is a cross-sectional view of power conversion device 1 taken along the A-A cross section in Fig. 2, with the interior of smoothing capacitor 6 indicated by a dashed line, Fig. 4 is a cross-sectional view of power conversion device 1 taken along the B-B cross section in Fig. 2, showing the portion around branch busbar 12 at the B-B cross section, Fig. 5 is a cross-sectional view of power conversion device 1 taken along the C-C cross section in Fig. 2, showing the portion around branch busbar 12 adjacent to the C-C cross section with part of main busbar 11 omitted, and Fig. 6 is a cross-sectional view of another power conversion device 1 taken along the same position as the B-B cross section in Fig. 2, showing the portion around branch busbar 12 at the B-B cross section. The power conversion device 1 is a device that converts, for example, an input current from DC to AC, or from AC to DC, or an input voltage to a different voltage.

[0015] <Power conversion device 1> The power conversion device 1 is mounted on an electrically powered vehicle such as an electric vehicle or a hybrid vehicle that uses a motor as one of its drive sources. In this embodiment, as shown in Fig. 1, the power conversion device 1 converts predetermined power (e.g., DC power) supplied from an external power source 2 into another predetermined power (e.g., AC power) and supplies the power to a load 3 (e.g., a motor). This embodiment shows a power conversion device 1 that outputs three-phase AC, and as shown in Fig. 2, the power module is composed of three power modules 7 corresponding to each phase. The configuration of the power conversion device 1 is not limited to this, and the power conversion device 1 may also be a device that converts an input current from AC to DC.

[0016] As shown in FIG. 1 , the power conversion device 1 includes a substrate 8 on which a filter circuit component 9 having one or more capacitors for removing noise is provided, a power module 7 having a power semiconductor element 7a, and main circuit wiring connected to the power module 7. At least a portion of the main circuit wiring is made up of a bus bar 30. In this embodiment, the power conversion device 1 further includes a housing 4 having a bottom wall 4c (not shown in FIG. 1 ) and accommodating the substrate 8 and the power module 7, and a smoothing capacitor 6 arranged alongside the power module 7 along the bottom wall 4c. In this embodiment, all of the main circuit wiring is made up of the bus bar 30, but this is not a limitation, and some of the main circuit wiring may be wiring provided on the substrate 8. The bus bar 30 is made of, for example, copper or an aluminum alloy, which has low electrical resistivity and excellent conductivity.

[0017] The main circuit section 5, which performs power conversion, is formed by a smoothing capacitor 6, which smooths DC power, and a power module 7. Filter circuit components 9 suppress electromagnetic noise generated by the main circuit section 5 during power conversion. In addition to the filter circuit components 9, the substrate 8 is provided with one or more other circuit components, such as control and power circuit components 10, which form the control circuit and drive circuit of the power module 7. The substrate 8 and the power module 7 are electrically connected by power module terminals 14 extending from the power module 7 toward the substrate 8. The substrate 8 and an external device 31 are electrically connected by control wiring 15.

[0018] <Branch Busbar 12> The branch busbar 12, which is a key part of the present disclosure, will now be described. The busbar 30 includes a main busbar 11 constituting the main circuit wiring and a branch busbar 12 branching from the main busbar 11, and the branch busbar 12 is electrically connected to the substrate 8. The external power supply 2, the main circuit unit 5, and the load 3, through which a large current flows, are electrically connected by the busbar 30 and the main busbar 11. Fig. 3 shows the positive-side branch busbar 12a, which is the branch busbar 12 branching from the positive-side main busbar 11a, which is the main busbar 11. Fig. 4 shows the positive-side branch busbar 12a and the negative-side branch busbar 12b, which is the branch busbar 12 branching from the negative-side main busbar 11b, which is the main busbar 11.

[0019] With this configuration, the bus bar 30 electrically connected to the main circuit unit 5 is branched, and is connected to the substrate 8 on which the filter circuit components 9 are provided by the branched branch bus bar 12. This shortens the length of the main bus bar 11 without routing the main bus bar 11 through which a large current flows, thereby reducing loss in the bus bar 30 and suppressing heat generation in the bus bar 30. The reduced loss in the bus bar 30 also reduces loss in the power conversion device 1. Furthermore, since no components for cooling the bus bar 30 are required, layout restrictions for cooling are eliminated, allowing the power conversion device 1 to be made smaller. Furthermore, the reduced need for components for cooling the bus bar 30 also allows the cost of the power conversion device 1 to be reduced.

[0020] 3 , in the present embodiment, the branch busbar 12 is connected to wiring (not shown in FIG. 3 ) on the substrate 8 adjacent to the filter circuit component 9, and is electrically connected to the filter circuit component 9 via the wiring on the substrate 8. With this configuration, the busbar 30 can be electrically connected to the filter circuit component 9 adjacent to the branch busbar 12 via the branch busbar 12, and the wiring of the branch busbar 12 electrically connected to the filter circuit component 9 can be separated from the busbar 30. This shortens the wiring distance between the filter circuit component 9 and the main busbar 11 and the length of the main busbar 11, thereby reducing loss in the busbar 30 and suppressing heat generation in the busbar 30. The reduced loss in the busbar 30 allows the power conversion device 1 to also reduce loss.

[0021] In this embodiment, the substrate 8 is provided opposite the power module 7 and the main bus bar 11, which is the main circuit wiring, with a gap between them, and the branch bus bar 12 extends from the main bus bar 11, which is the main circuit wiring, toward the substrate 8 and is electrically connected to the filter circuit components 9 via the wiring of the substrate 8. With this configuration, the wiring distance between the filter circuit components 9 and the main bus bar 11 is shortened, thereby suppressing the effects of noise superimposed on the branch bus bar 12. Furthermore, because the distance between the substrate 8 and the power module 7 and the main bus bar 11 is shortened, the power conversion device 1 can be made more compact.

[0022] <Housing 4, Cover 18> Next, the configuration of each part of the power conversion device 1 will be described in detail. First, the housing 4 and the cover 18 will be described. The housing 4 is formed, for example, in a cylindrical shape with a bottom. The inside of the housing 4 is a component housing section that houses each component. An outer wall 4a, which is a peripheral wall erected from a bottom wall 4c, is formed around the component housing section. The plate-shaped cover 18 covers the open portion of the housing 4, thereby forming a box-like shape with a sealed interior. The potential of the housing 4 and the cover 18 is ground. The shapes of the housing 4 and the cover 18 are not limited thereto, and the cover 18 may also be formed in a cylindrical shape with a bottom. The housing 4 and the cover 18 are made of, for example, a metal material such as an aluminum alloy. The housing 4 and the cover 18 are manufactured by, for example, aluminum die-casting. The housing 4 and the cover 18 may also be made of sheet metal made of a metal material with high magnetic permeability (for example, iron). By constructing the housing 4 and cover 18 from a metal with high magnetic permeability, an electromagnetic shielding effect can be obtained, making it easier to suppress the intrusion and radiation of noise, and by constructing them from sheet metal, the cost of the power conversion device 1 can be reduced compared to forming them using aluminum die-cast molding.

[0023] The housing 4 has an inner wall 4b, which is a portion of the housing 4 that protrudes from a bottom wall 4c on the inside of the housing 4. As shown in FIG. 2, both ends of the inner wall 4b are connected to the outer wall 4a, forming small compartments 16a, 16b surrounded by the inner wall 4b and the outer wall 4a. In this embodiment, two small compartments 16a, 16b are formed in the housing 4, but this is not limited to this. A configuration in which additional small compartments are formed and other components are placed in the small compartments may also be used. In this embodiment, the inner wall 4b has a boss 4b2. The board 8 is fixed to the housing 4 using the boss 4b2, for example, with a screw. The boss 4b2 is formed not only on the inner wall 4b but also on the outer wall 4a.

[0024] In this embodiment, as shown in FIG. 3 , a refrigerant flow path 17 for cooling the power module 7 is provided in the bottom wall 4 c of the housing 4. The power module 7 is thermally connected to the portion of the bottom wall 4 c where the refrigerant flow path 17 is provided. The thermal connection is not limited to a configuration in which the bottom wall 4 c and the power module 7 are connected by direct contact. The bottom wall 4 c and the power module 7 may also be thermally connected via a heat-conducting member such as grease or a heat-dissipating sheet. A refrigerant flows through the refrigerant flow path 17. For example, the refrigerant may be a liquid such as water or ethylene glycol liquid, or a gas such as air. The housing 4 has a refrigerant inlet / outlet (not shown) through which the refrigerant flows in and out. Multiple cooling fins may be provided on the portion of the refrigerant flow path 17 facing the power module 7. The refrigerant flow path 17 may also be provided on the side of the bottom wall 4 c where the smoothing capacitor 6 is provided.

[0025] <Bus Bar 30> Next, the bus bar 30 will be described. As shown in FIG. 1 , the bus bar 30 has an external power supply bus bar 21 that is connected to the external power supply 2. As shown in FIG. 2 , the external power supply bus bar 21 is connected to the main bus bar 11 inside the housing 4. Power is supplied to the external power supply bus bar 21 from the outside. The external power supply bus bar 21 is composed of a positive-side external power supply bus bar 21a that is a positive-side bus bar portion and a negative-side external power supply bus bar 21b that is a negative-side bus bar portion. As shown in FIG. 3 , the positive-side external power supply bus bar 21a and the negative-side external power supply bus bar 21b pass through outer-wall through-holes 4a1 formed in the outer wall 4a and are provided inside the external power supply connection portion 20. The external power supply connection portion 20 is fixed to the outer wall 4a of the housing 4 on the side where the filter circuit component 9 is arranged. The external power supply connection portion 20 is a connector that is connected to the external power supply 2. The external power supply connection part 20 is made of a highly heat-resistant resin material such as PPS. The outer wall through-hole 4a1 is sealed by the external power supply connection part 20, and the inside of the housing 4 is hermetically sealed. The external power supply connection part 20 and the housing of the external power supply 2 may be sealed together, or the external power supply connection part 20 may be configured as a panel-mounted connector.

[0026] The main busbar 11 and the branch busbars 12 each include a positive busbar portion and a negative busbar portion, with at least a portion of the positive busbar portion and the negative busbar portion facing each other. As shown in FIG. 2 , the main busbar 11 includes a positive main busbar 11a, which is the positive busbar portion, and a negative main busbar 11b, which is the negative busbar portion. The branch busbar 12 includes a positive branch busbar 12a, which is the positive busbar portion, and a negative branch busbar 12b, which is the negative busbar portion. The opposing positive busbar portion and negative busbar portion are parallel plate portions so that the current flows in opposite directions when a high-frequency current is applied. The parallel plate portions of the main busbar 11 are shown in FIG. 3 , and the parallel plate portions of the branch busbars 12 are shown in FIG. 4 .

[0027] By forming these parallel plate portions, the magnetic flux generated in the busbars is concentrated inside the busbars, reducing high-frequency resistance and heat loss in the busbars. Furthermore, the magnetic flux generated in the busbars is canceled outside the busbars, suppressing the occurrence of parasitic inductance. Furthermore, because the opposing surfaces of the opposing busbars are covered by the opposing busbars, there are no open busbars, making noise coupling less likely.

[0028] The external power supply bus bar 21 and the main bus bar 11 are connected to an external power supply terminal block 19 provided adjacent to the outer wall 4a inside the small chamber 16a of the housing 4. The external power supply terminal block 19 is formed, for example, in a rectangular parallelepiped shape from a resin material. The external power supply terminal block 19 is provided in contact with the bottom wall 4c. The positive external power supply bus bar 21a and the positive main bus bar 11a are provided overlapping and electrically connected on the surface of the external power supply terminal block 19 opposite the bottom wall 4c. The negative external power supply bus bar 21b and the negative main bus bar 11b are provided overlapping and electrically connected on the surface of the external power supply terminal block 19 opposite the bottom wall 4c. The connection between the positive external power supply bus bar 21a and the positive main bus bar 11a, and the connection between the negative external power supply bus bar 21b and the negative main bus bar 11b are connected by, for example, welding or screws. The electrical connection between the metal parts is not limited to this, and other methods of connection such as connection via solder may also be used.

[0029] In this embodiment, as shown in Fig. 2, branch bus bar 12 branches off from main bus bar 11 at a position inside small chamber 16a adjacent to external power supply side terminal block 19. After branching, branch bus bar 12 is bent toward board 8 and inserted into board 8 as shown in Fig. 4. Branch bus bar 12 inserted into board 8 is electrically connected to wiring provided on board 8 by, for example, solder (not shown).

[0030] The inner wall 4b has an inner-wall through-hole 4b1, which is a through-hole, and the main bus bar 11 passes through the inner-wall through-hole 4b1. The main bus bar 11 that passes through the inner-wall through-hole 4b1 is electrically connected to the main circuit unit 5. With this configuration, the length of the main bus bar 11 is shortened, which reduces loss in the bus bar 30 and suppresses heat generation in the bus bar 30. Since the bus bar 30 has low loss, the power conversion device 1 also has low loss.

[0031] In the present embodiment, the main busbar 11 and the branch busbars 12 are formed from the same integrated member, but this is not limiting. The main busbar 11 and the branch busbars 12 may be formed from separate busbars and connected to each other, for example, by welding or screws. The main busbar 11 and the branch busbars 12 may be formed from different metals and connected to each other. Forming the main busbar 11 and the branch busbars 12 from the same integrated member reduces the number of parts, thereby reducing the cost of the power converter 1. Forming the main busbar 11 and the branch busbars 12 from separate busbars allows the same main busbar 11 to be used for wiring on different boards. This enables the main busbar 11 to be used for a variety of products, thereby reducing the development time and man-hours for the power converter 1. Forming the main busbar 11 and the branch busbars 12 from different metals facilitates value-added configurations. An example of a value-added configuration is a configuration in which the branch busbar 12 is changed to a high-strength metal to increase the vibration resistance of the substrate 8, or a configuration in which the shape of a portion of the branch busbar 12 is changed to reduce the cross-sectional area thereof to suppress heat transfer, thereby suppressing thermal damage to the substrate 8 caused by the branch busbar 12.

[0032] As shown in FIG. 1 , the bus bar 30 includes a load-connecting bus bar 23 connected to the load 3. As shown in FIG. 2 , the load-connecting bus bar 23 is connected to the main bus bar 11 inside the housing 4. The load-connecting bus bar 23 supplies power to the outside. In this embodiment, three power modules 7 are provided, and therefore the load-connecting bus bar 23 is connected to each of the main bus bars 11 of the three power modules 7. As shown in FIG. 3 , the load-connecting bus bar 23 passes through an outer-wall through-hole 4 a 1 formed in the outer wall 4 a and is provided inside the load connection portion 22. The load connection portion 22 is fixed to the outer wall 4 a of the housing 4 on the side of the power module main terminal 13 b opposite the side of the smoothing capacitor 6 of the power module 7. The load connection portion 22 is a connector connected to the load 3. The load connection portion 22 is made of a resin material having high heat resistance, such as PPS. The outer-wall through-hole 4 a 1 is sealed by the load connection portion 22, and the inside of the housing 4 is hermetically sealed.

[0033] The load connection busbar 23 and the main busbar 11 are connected at a load side terminal block 24 provided adjacent to the outer wall 4a. The load side terminal block 24 is formed, for example, in a rectangular parallelepiped shape from a resin material. The load side terminal block 24 is provided in contact with the bottom wall 4c. The load connection busbar 23 and the main busbar 11 are provided overlapping on the surface of the load side terminal block 24 opposite the bottom wall 4c side, and are electrically connected. The load connection busbar 23 and the main busbar 11 are connected, for example, by welding or screws. The electrical connection between the metal parts is not limited to this, and other methods, such as connection via solder, may also be used.

[0034] <Smoothing Capacitor 6> Next, the smoothing capacitor 6 will be described. As shown in FIG. 3 , the smoothing capacitor 6 includes a capacitor element 6a, a capacitor main bus bar 11c that is a portion of the main bus bar 11 connected to the capacitor element 6a, and a capacitor case 6b that houses these. A sealing material is filled inside the capacitor case 6b. The sealing material is an insulating material made of epoxy resin or the like. The capacitor element 6a smoothes DC power. The capacitor element 6a is, for example, a film capacitor having a laminated structure in which a metal foil and a resin film that serve as internal electrodes are wound into a roll. The capacitor element 6a has electrodes (not shown) on both ends. Each electrode is a positive electrode or a negative electrode. The portion of the capacitor main bus bar 11c of the positive-side main bus bar 11a is connected to the positive electrode, and the portion of the capacitor main bus bar 11c of the negative-side main bus bar 11b is connected to the negative electrode.

[0035] Although the present embodiment shows an example in which one capacitor element 6a is provided, the number of capacitor elements 6a is not limited to this. Three capacitor elements may be provided, and each of the three capacitor elements may be connected to each of the three power modules 7. The capacitor case 6b is made of, for example, aluminum die-cast molding or a resin material having high heat resistance, such as PPS.

[0036] <Power Module 7> Next, the power module 7 will be described. As shown in FIG. 2, the power module 7 is disposed adjacent to the smoothing capacitor 6. As shown in FIG. 3, the power module 7 includes a power semiconductor element 7a (not shown in FIG. 3) for power conversion, a power module main terminal 13a connected to the smoothing capacitor 6 via the main bus bar 11, a power module main terminal 13b connected to the load-connecting bus bar 23 via the main bus bar 11, and multiple power module terminals 14 connected to the substrate 8. The power module main terminal 13a is disposed on the side of the smoothing capacitor 6, and the power module main terminal 13b is disposed on the side of the outer wall 4a opposite the side of the smoothing capacitor 6. The power semiconductor element 7a is sealed, for example, by a sealing resin that surrounds the power semiconductor element 7a. The power module main terminals 13a, 13b and the power module terminal 14 are made, for example, of copper or aluminum alloy, which have low electrical resistivity and excellent conductivity. The number of power semiconductor elements 7a may be one or more.

[0037] The power semiconductor element 7a may be a power control semiconductor element such as a MOSFET (Metal Oxide Semiconductor Field Effect Transistor) or an IGBT (Insulated Gate Bipolar Transistor), or a free wheel diode. The power semiconductor element 7a is not limited to these, and may be other semiconductor elements such as a bipolar transistor. Alternatively, the power semiconductor element 7a may be a reverse conducting IGBT (RC-IGBT) in which a switching element and a free wheel diode are integrated.

[0038] The power semiconductor element 7a is formed on a semiconductor substrate made of a material such as silicon, silicon carbide, or gallium nitride, and a wide bandgap semiconductor element having a wider bandgap than silicon can be used for the power semiconductor element 7a. When a MOSFET formed of silicon carbide, which is a wide bandgap semiconductor element, is used, the time change di / dt of current generated during switching can be made larger than that of a MOSFET formed of silicon. Furthermore, wide bandgap semiconductor elements have low on-resistance, low loss, and low heat generation, allowing for a reduction in chip area. Because the chip area is reduced, the power module 7 can be made smaller.

[0039] <Substrate 8> The substrate 8 is, for example, a printed circuit board formed of a multilayer substrate. As shown in FIG. 3 , the substrate 8 is disposed on the opening side of the housing 4 above the main circuit unit 5 so as to overlap at least a portion of the smoothing capacitor 6 and the power module 7, which are the main circuit unit 5 including the main bus bar 11. The substrate 8 and the power module 7 are connected by a plurality of power module terminals 14 provided on the power module 7. The substrate 8 is fixed to bosses 4b2 provided on the inner wall 4b and bosses 4b2 provided adjacent to the outer wall 4a of the housing 4, for example, with screws. It is preferable that the substrate 8 be fixed at multiple locations. Fixing the substrate 8 at multiple locations can improve the vibration resistance and heat dissipation of the substrate 8.

[0040] As shown in FIG. 1 , the substrate 8 has a control wiring 15 connected to an external device 31. As shown in FIG. 2 , the control wiring 15 is electrically connected to the substrate 8 inside a small chamber 16 b provided in the housing 4. A control signal is sent from the external device 31 to a circuit provided on the substrate 8 via the control wiring 15. The control wiring 15 passes through an outer wall through-hole (not shown) formed in the outer wall 4 a and is provided inside the external device connection portion 25. The external device connection portion 25 is fixed to the outer wall 4 a of the housing 4 on the side where the smoothing capacitor 6 is located. The external device connection portion 25 is a connector connected to the external device 31. The external device connection portion 25 is made of a highly heat-resistant resin material, such as PPS. The outer wall through-hole is sealed by the external device connection portion 25, sealing the inside of the housing 4. Because the control wiring 15 and the main circuit unit 5 are separated by the inner wall 4 b forming the small chamber 16 b, the influence of noise from the main circuit unit 5 on the control wiring 15 can be suppressed.

[0041] The capacitors included in the filter circuit component 9 are either or both of an X capacitor and a Y capacitor. In this embodiment, the filter circuit component 9 includes both an X capacitor and a Y capacitor. The X capacitor is electrically connected between the positive branch bus bar 12a and the negative branch bus bar 12b of the branch bus bar 12 to reduce normal mode noise. The Y capacitors are connected between the positive branch bus bar 12a and a ground connected to the housing 4, and between the negative branch bus bar 12b and a ground connected to the housing, to remove common mode noise. By providing either or both of the X capacitor and the Y capacitor in the filter circuit component 9 in this way, noise generated in the power conversion device 1 can be efficiently removed.

[0042] In this embodiment, because the filter circuit components 9 are arranged on the substrate 8, when a change occurs in the required noise performance of the power conversion device 1, the changed requirement can be easily accommodated simply by changing the components mounted on the substrate 8. Furthermore, in this embodiment, the filter circuit components 9 are arranged on the main circuit unit 5 side of the board surface of the substrate 8, but this is not limitative and the filter circuit components 9 may be arranged on the opening side of the housing 4. When the filter circuit components 9 are arranged on the main circuit unit 5 side, the inner wall 4b suppresses noise from the main circuit unit 5 to the filter circuit components 9, and when the filter circuit components 9 are arranged on the opening side, the substrate 8 suppresses noise from the main circuit unit 5 to the filter circuit components 9.

[0043] <Shield> The power conversion device 1 includes a shield that is grounded in contact with the substrate 8 and disposed adjacent to the filter circuit components 9. In this embodiment, as shown in FIG. 3 , the shield is formed by the inner wall 4b that defines the small chamber 16a. At least a portion of the inner wall 4b is connected to a ground pattern disposed on the substrate 8. The ground pattern is, for example, a solid pattern disposed on the substrate surface. In this embodiment, the ground pattern is a housing ground pattern 32. The shield is disposed between the filter circuit components 9 and one or more other circuit components, namely, the control and power circuit components 10, disposed on the substrate 8, and separates the filter circuit components 9 from the control and power circuit components 10. By providing the shield that separates the filter circuit components 9 from the control and power circuit components 10, the influence of noise from the control and power circuit components 10 on the filter circuit components 9 can be reduced, thereby suppressing the influence of noise.

[0044] In this embodiment, the shield is disposed between the control and power circuit components 10 and the filter circuit components 9 and branch bus bar 12, separating the control and power circuit components 10 from the filter circuit components 9 and branch bus bar 12. This configuration reduces the influence of noise from the control and power circuit components 10 on the branch bus bar 12, including the portion of the external power supply side terminal block 19, and the filter circuit components 9, thereby suppressing the influence of noise. It also reduces layout constraints for noise suppression. Furthermore, by providing a curved inner wall 4b, the main circuit unit 5 and the filter circuit components 9 can be arranged overlapping each other, thereby reducing noise and eliminating wasted space, thereby enabling the power conversion device 1 to be made smaller.

[0045] In this embodiment, the inner wall 4b forms a shield, and the main bus bar 11 passes through the inner-wall through-hole 4b1. With this configuration, the inner wall 4b, which is part of the housing 4, abuts against the circuit board 8, and the circuit board 8 is fixed to the inner wall 4b. This strengthens the connection between the ground pattern of the circuit board 8 and the housing ground, thereby reducing the impact of noise on the circuit board 8. Furthermore, the main bus bar 11 passes through the inner-wall through-hole 4b1 to be electrically connected to the main circuit unit 5. This ensures contact with the circuit board surface of the circuit board 8 on the surface of the inner wall 4b facing the circuit board 8, while allowing the electrical connection with the main circuit unit 5 to be made using the smallest inner-wall through-hole 4b1. This suppresses the impact of noise from the main circuit unit 5 on the filter circuit components 9.

[0046] <Layout of Components of Power Conversion Device 1 and Other Configurations> The layout of components of the power conversion device 1 and other configurations will be described. In this embodiment, as shown in FIG. 2 , the filter circuit components 9 are provided adjacent to a portion of the peripheral wall surrounding the bottom surface of the smoothing capacitor 6 on the side opposite the power module 7. In this embodiment, the peripheral wall of the smoothing capacitor 6 is a capacitor case 6b formed in a rectangular shape when viewed from the opening side of the housing 4. The filter circuit components 9 are arranged inside the small chamber 16a and are electrically connected to the branch bus bar 12 and the circuit board 8 inside the small chamber 16a. At least a portion of the board surface of the circuit board 8 is a solid pattern to separate the filter circuit components 9 provided on the circuit board 8 from the control and power circuit components 10 other than the filter circuit components 9. A portion of the solid pattern is connected to the chassis ground. The portion of the chassis ground to which the solid pattern is connected is, for example, the inner wall 4b to which the circuit board 8 is fixed.

[0047] By providing the filter circuit component 9 adjacent to a portion of the peripheral wall surrounding the bottom surface of the smoothing capacitor 6 on the side opposite to the power module 7, it is possible to increase the distance between the filter circuit component 9 and the power module 7, which is one of the noise sources, and thereby reduce the influence of noise on the filter circuit component 9 from the power module 7. Furthermore, because the influence of noise is reduced, for example, the capacitance of the filter circuit component 9 can be reduced, thereby making it possible to reduce the size and cost of the filter circuit component 9. Furthermore, to reduce the influence of noise, a cutout of, for example, several millimeters can be provided in part of the configuration of the small chamber 16a, and components can be placed in the cutout, thereby alleviating layout constraints and reducing the size of the power conversion device 1.

[0048] In this embodiment, the branch bus bar 12, the filter circuit components 9, and the inner wall 4b, which serves as a shield, are provided adjacent to the connection between the external power supply bus bar 21 and the main bus bar 11. This configuration reduces the effect of noise on the filter circuit components 9, including the external power supply bus bar 21 connected to the outside. It also makes it possible to reduce the size of the filter circuit components 9 portion where the shield is provided. Because the filter circuit components 9 portion is reduced in size, the power conversion device 1 can be made smaller.

[0049] In this embodiment, as shown in FIG. 3 , the substrate 8 has a wiring pattern on the surface of the substrate 8 where the inner wall 4b, which serves as a shield, abuts. The inner wall 4b and the wiring pattern are electrically connected, and at least a portion of the wiring pattern is a chassis ground pattern 32 connected to the housing 4. This configuration reduces the effects of noise passing through the substrate surface of the substrate 8. Furthermore, because the chassis ground pattern 32 is connected to the housing 4 not only electrically but also thermally, the number of heat dissipation paths for the substrate 8 is increased, facilitating heat dissipation from the substrate 8 and suppressing heat transfer to components mounted on the substrate 8. Furthermore, because the substrate 8 abuts against the housing 4, the vibration resistance of the substrate 8 is ensured. Therefore, components with low vibration resistance can be mounted adjacent to the abutting portion, facilitating the layout of the substrate 8.

[0050] 4, in this embodiment, the substrate 8 is a multi-layer substrate, and the inner layer of the substrate 8 has an inner layer housing ground pattern 33 connected to the housing ground pattern 32. With this configuration, the influence of noise passing through the inner layer of the substrate 8 can be reduced, and the influence of noise can be suppressed.

[0051] In this embodiment, as shown in Fig. 3, the power module 7, bus bar 30, and inner wall 4b, which serves as a shield, are provided on one surface 8a of the substrate 8, and the power module 7 is covered by the substrate 8. The bus bar 30 shown in Fig. 3 is the main bus bar 11. With this configuration, the power module 7 and inner wall 4b, which are noise sources, are concentrated on the one surface 8a of the substrate 8, making it easy to block noise with the inner wall 4b.

[0052] In this embodiment, the housing 4 is formed in a cylindrical shape with a bottom, and one surface 8a of the substrate 8 faces the bottom wall 4c. The power module 7, the inner wall 4b serving as a shield, and the filter circuit components 9 are arranged along the bottom wall 4c in this order, with the inner wall 4b separating the power module 7 and the filter circuit components 9. With this configuration, the power module 7 and the filter circuit components 9 are separated by the inner wall 4b, so that the influence of noise from the power module 7 on the filter circuit components 9 can be reliably suppressed.

[0053] In this embodiment, as shown in Fig. 2, the small rooms 16a and 16b are provided separately, but this is not limiting. The small rooms 16a and 16b may be provided integrally. By providing the small rooms 16a and 16b integrally, the inner wall 4b can be eliminated, and layout restrictions due to the inner wall 4b can be alleviated, thereby making it possible to miniaturize the power conversion device 1. Furthermore, since the material cost of the housing 4 is reduced, the cost of the power conversion device 1 can be reduced.

[0054] In the present embodiment, the external power supply side terminal block 19 and the smoothing capacitor 6 are configured as separate bodies, but this is not limiting and the external power supply side terminal block 19 and the smoothing capacitor 6 may be configured as an integrated unit. An integrated configuration is, for example, a configuration in which the external power supply side terminal block 19 does not abut against the bottom wall 4c, but extends from the capacitor case 6b through the inner wall through-hole 4b1 into the small chamber 16a. This configuration reduces wasted space between the inner wall 4b and the external power supply side terminal block 19, allowing the power conversion device 1 to be further miniaturized.

[0055] <Modification> A modification in which an additional shield 26 is provided in addition to the above-described configuration will be described with reference to FIG. 6 . The inner wall 4b, which serves as the shield, is provided on one surface 8a of the substrate 8. The power conversion device 1 further includes an additional shield 26 that abuts against the other surface 8b of the substrate 8 and is grounded to the substrate 8 and the housing 4. At least a portion of the additional shield 26 overlaps the inner wall 4b via the substrate 8. In this embodiment, the additional shield 26 is a portion of the cover 18 that protrudes from the cover 18 toward the other surface 8b of the substrate 8. The additional shield 26 is grounded to the housing 4 via the cover 18. The additional shield 26 separates the filter circuit components 9 from the control and power circuit components 10 on the other surface 8b of the substrate 8.

[0056] With this configuration, it is possible to block and suppress noise generated by, for example, the control and power circuit components 10 from propagating to the filter circuit components 9, even on the other surface 8b of the substrate 8. Because noise propagating to the filter circuit components 9 can be blocked and suppressed on both the one surface 8a and the other surface 8b of the substrate 8, it is possible to alleviate restrictions on the placement of the filter circuit components 9 due to the influence of noise. Because restrictions on the placement of the filter circuit components 9 are alleviated, it is possible to reduce the placement area of ​​the filter circuit components 9 and make the substrate 8 more compact.

[0057] Because the additional shield 26, which is grounded to the housing 4, abuts against the board 8, the number of heat dissipation paths for the board 8 increases, facilitating heat dissipation from the board 8 and suppressing heat transfer to components provided on the board 8. Furthermore, because the board 8 abuts against the housing 4 and the additional shield 26, the vibration resistance of the board 8 is ensured, and components with low vibration resistance can be mounted in positions adjacent to the abutting parts, facilitating the layout of the board 8.

[0058] The additional shield 26 is not limited to being provided integrally with the cover 18. The additional shield 26 may be formed of a separate metal member grounded to the housing 4, with at least a portion of the additional shield 26 abutting against the substrate 8. Alternatively, the additional shield 26 may be a portion of the cover 18 formed by recessing a portion of the cover 18 toward the other surface 8b of the substrate 8, for example, by press working.

[0059] As described above, the power conversion device 1 according to the first embodiment includes the substrate 8 on which the filter circuit components 9 are provided, the power module 7, and the main circuit wiring connected to the power module 7. At least a portion of the main circuit wiring is formed by the busbar 30. The busbar 30 includes the main busbar 11 constituting the main circuit wiring and the branch busbar 12 branching from the main busbar 11. The branch busbar 12 is electrically connected to the substrate 8, so that the busbar 30 electrically connected to the power module 7 is branched and connected to the substrate 8 on which the filter circuit components 9 are provided by the branched branch busbar 12. This allows the length of the main busbar 11, through which a large current flows, to be shortened, thereby reducing loss in the busbar 30 and suppressing heat generation in the busbar 30. The reduced loss in the busbar 30 allows the power conversion device 1 to have reduced loss. Furthermore, because no components for cooling the busbar 30 are required, layout constraints for cooling are eliminated, allowing the power conversion device 1 to be made smaller. Furthermore, since no member for cooling the bus bar 30 is required, the cost of the power conversion device 1 can be reduced.

[0060] When the branch busbar 12 is connected to the wiring on the substrate 8 adjacent to the filter circuit component 9 and is electrically connected to the filter circuit component 9 via the wiring on the substrate 8, the busbar 30 can be electrically connected to the filter circuit component 9 adjacent to the branch busbar 12 via the branch busbar 12, and the wiring of the branch busbar 12 electrically connected to the filter circuit component 9 can be separated from the busbar 30. This reduces the wiring distance between the filter circuit component 9 and the main busbar 11 and the length of the main busbar 11, thereby reducing loss in the busbar 30 and suppressing heat generation in the busbar 30. Because the busbar 30 has low loss, the power conversion device 1 also has low loss.

[0061] When the substrate 8 is provided opposite, with a gap between, the power module 7 and the main bus bar 11 that is the main circuit wiring, and the branch bus bar 12 extends from the main bus bar 11 of the main circuit wiring toward the substrate 8 and is electrically connected to the filter circuit components 9 via the wiring of the substrate 8, the wiring distance between the filter circuit components 9 and the main bus bar 11 is shortened, thereby suppressing the effects of noise superimposed on the branch bus bar 12. Furthermore, because the distance between the substrate 8 and the power module 7 and the main bus bar 11 is shortened, the power conversion device 1 can be made smaller.

[0062] If the power conversion device 1 further includes a housing 4 having a bottom wall 4c and accommodating a substrate 8 and a power module 7, and a smoothing capacitor 6 arranged alongside the power module 7 along the bottom wall 4c, and the filter circuit component 9 is provided adjacent to a portion of the peripheral wall surrounding the bottom surface of the smoothing capacitor 6 on the side opposite to the power module 7, it is possible to increase the distance between the filter circuit component 9 and the power module 7, which is one of the noise sources, and thereby reduce the influence of noise from the power module 7 on the filter circuit component 9. Furthermore, because the influence of noise is reduced, for example, the capacitance of the filter circuit component 9 can be reduced, thereby enabling the filter circuit component 9 to be made smaller and less expensive.

[0063] When the power conversion device 1 is further provided with a shield that is grounded in contact with the substrate 8 and is provided adjacent to the filter circuit components 9, and the shield is disposed between the filter circuit components 9 and one or more other circuit components, that is, the control and power circuit components 10, provided on the substrate 8, and separates the filter circuit components 9 from the control and power circuit components 10, the influence of noise from the control and power circuit components 10 on the filter circuit components 9 can be reduced, and the influence of noise can be suppressed.

[0064] When the shield is disposed between the control and power circuit components 10, which are other circuit components, and the filter circuit components 9 and branch bus bar 12, and separates the control and power circuit components 10 from the filter circuit components 9 and branch bus bar 12, the influence of noise from the control and power circuit components 10 on the branch bus bar 12 including the portion of the external power supply side terminal block 19 and the filter circuit components 9 can be reduced, and the influence of noise can be suppressed. In addition, layout restrictions for noise suppression can be reduced.

[0065] When the housing 4 has an inner wall 4b that is a part of the housing 4 protruding from a portion of the bottom wall 4c inside the housing 4, the inner wall 4b forms a shield, the inner wall 4b has an inner-wall through-hole 4b1 that is a through-hole, and the main busbar 11 passes through the inner-wall through-hole 4b1, the inner wall 4b that is a part of the housing 4 abuts against the circuit board 8 and the circuit board 8 is fixed to the inner wall 4b, thereby strengthening the connection between the ground pattern of the circuit board 8 and the housing ground and reducing the impact of noise on the circuit board 8. Furthermore, the main busbar 11 passes through the inner-wall through-hole 4b1 and is electrically connected to the main circuit unit 5. This ensures contact between the surface of the inner wall 4b facing the circuit board 8 and the surface of the circuit board 8, while allowing the electrical connection with the main circuit unit 5 to be configured with the smallest inner-wall through-hole 4b1. This reduces the impact of noise from the main circuit unit 5 on the filter circuit components 9.

[0066] When the bus bar 30 has an external power supply bus bar 21 connected to the external power supply 2, the external power supply bus bar 21 is connected to the main bus bar 11 inside the housing 4, and the branch bus bar 12, the filter circuit components 9, and the inner wall 4b serving as a shield are provided adjacent to the connection between the external power supply bus bar 21 and the main bus bar 11, the influence of noise on the filter circuit components 9 including the external power supply bus bar 21 connected to the outside can be reduced. Furthermore, the portion of the filter circuit components 9 provided with the shield can be made smaller. Because the portion of the filter circuit components 9 is made smaller, the power conversion device 1 can be made smaller.

[0067] If the substrate 8 has a wiring pattern on the substrate surface of the substrate 8 where the inner wall 4b, which serves as a shield, abuts, the inner wall 4b and the wiring pattern are electrically connected, and at least a portion of the wiring pattern is a housing ground pattern 32 connected to the housing 4, it is possible to reduce the effects of noise passing through the substrate surface of the substrate 8. Furthermore, since the housing ground pattern 32 is connected to the housing 4 not only electrically but also thermally, the number of heat dissipation paths for the substrate 8 is increased, facilitating heat dissipation from the substrate 8 and suppressing heat transfer to components provided on the substrate 8. Furthermore, since the substrate 8 abuts against the housing 4, the vibration resistance of the substrate 8 is ensured, and components with low vibration resistance can be mounted adjacent to the abutting portion, facilitating the layout of the substrate 8.

[0068] When the substrate 8 is a multilayer substrate and the inner layer of the substrate 8 has an inner layer housing ground pattern 33 connected to the housing ground pattern 32, the influence of noise passing through the inner layer of the substrate 8 can be reduced and the influence of noise can be suppressed.

[0069] When the power module 7, the bus bar 30, and the inner wall 4b serving as the shield are provided on one surface 8a of the substrate 8 and the power module 7 is covered by the substrate 8, the power module 7 and the inner wall 4b, which are noise sources, are concentrated on the one surface 8a side of the substrate 8, making it easy to block noise by the inner wall 4b.

[0070] When the housing 4 is formed in a cylindrical shape with a bottom, one surface 8a of the substrate 8 faces the bottom wall 4c, the power module 7, the inner wall 4b serving as a shield, and the filter circuit components 9 are arranged in this order along the bottom wall 4c, and the inner wall 4b separates the power module 7 from the filter circuit components 9, the effect of noise from the power module 7 on the filter circuit components 9 can be reliably suppressed because the power module 7 and the filter circuit components 9 are separated by the inner wall 4b.

[0071] When the inner wall 4b, which is a shield, is provided on one side 8a of the substrate 8, the power conversion device 1 further includes an additional shield 26 that abuts the other side 8b of the substrate 8 and is grounded to the substrate 8 and the housing 4, and at least a portion of the additional shield 26 is stacked on the inner wall 4b via the substrate 8, noise generated by, for example, the control and power circuit components 10 can be blocked and suppressed from propagating to the filter circuit components 9, even on the other side 8b of the substrate 8. Because noise propagating to the filter circuit components 9 can be blocked and suppressed on both the side of the one side 8a and the side of the other side 8b of the substrate 8, restrictions on the placement of the filter circuit components 9 due to the influence of noise can be alleviated. Since restrictions on the placement of the filter circuit components 9 are alleviated, the placement area of ​​the filter circuit components 9 can be reduced, and the substrate 8 can be made smaller.

[0072] When the main busbar 11 and the branch busbars 12 are each composed of a positive busbar portion and a negative busbar portion, and at least a portion of the positive busbar portion and the negative busbar portion are arranged facing each other, magnetic flux generated in the busbars is concentrated inside the busbars, thereby reducing high-frequency resistance and heat loss in the busbars. Furthermore, magnetic flux generated in the busbars is canceled outside the busbars, thereby suppressing the occurrence of parasitic inductance.

[0073] When the capacitor included in the filter circuit component 9 is one or both of an X capacitor and a Y capacitor, noise generated in the power conversion device 1 can be efficiently removed.

[0074] Second Embodiment A power conversion device 1 according to a second embodiment will now be described. Fig. 7 is a plan view showing a main part of the power conversion device 1 according to the second embodiment, in which the cover 18 is removed from the power conversion device 1 and only the outline of the board 8 is shown, showing the arrangement of components around the branch bus bar 12; Fig. 8 is a cross-sectional view of the main part of the power conversion device 1 taken along the line D-D in Fig. 7; Fig. 9 is a cross-sectional view of the main part of the power conversion device 1 taken along the line E-E in Fig. 7, showing the area around the separate shield 27 at the line E-E; and Fig. 10 is a cross-sectional view of another power conversion device according to the second embodiment. 1 is a plan view showing a main part of still another power conversion device 1 according to embodiment 2, showing the same parts as in FIG. 7, FIG. 11 is a plan view showing a main part of yet another power conversion device 1 according to embodiment 2, showing the same parts as in FIG. 7, FIG. 12 is a cross-sectional view of the main part of yet another power conversion device 1 taken along the F-F cross section in FIG. 11, FIG. 13 is a plan view showing the main part of yet another power conversion device 1 according to embodiment 2, showing the same parts as in FIG. 7, and FIG. 14 is a cross-sectional view of the main part of yet another power conversion device 1 taken along the G-G cross section in FIG. 13. The shield of the power conversion device 1 shown in embodiment 1 was the inner wall 4b of the housing 4, but the power conversion device 1 according to embodiment 2 is configured to have a separate shield 27 that is not part of the housing 4.

[0075] As shown in FIG. 9 , the portion of the separate shield 27, which serves as a shield, opposite the portion that abuts against the substrate 8 and is grounded abuts against the housing 4, excluding at least the wiring arrangement portion. The main bus bar 11 penetrates the space of the wiring arrangement portion. The portion of the main bus bar 11 that penetrates the space, the separate shield 27, and the substrate 8 are arranged in order in a direction away from the bottom wall 4c of the housing 4. In this embodiment, the portion of the housing 4 that the separate shield 27 abuts is the inner wall 4b. A cutout 4b3 is provided in the inner wall 4b, and the portion of the cutout 4b3 covered by the separate shield 27 forms the wiring space 28, which is the space for the wiring arrangement portion. The main bus bar 11 penetrates the wiring space 28. The portion of the main bus bar 11 that penetrates the wiring space 28 is positioned so that it at least partially overlaps the inner wall 4b, the cutout 4b3, the separate shield 27, and the substrate 8 when viewed perpendicular to the bottom wall 4c.

[0076] 7, the small compartment 16a is formed by an outer wall 4a, an inner wall 4b, and a separate shield 27. The external power supply side terminal block 19 and the branch bus bar 12 provided inside the small compartment 16a are separated from the main circuit section 5 by the outer wall 4a, the inner wall 4b, and the separate shield 27. In addition, the filter circuit components 9 provided in the portion of the board 8 inside the small compartment 16a are separated from the control and power circuit components 10 by the outer wall 4a, the inner wall 4b, and the separate shield 27.

[0077] By providing the separate shield 27 and forming the small chamber 16a, as shown in FIG. 8 , the power converter 1 can be easily assembled by simply arranging the main bus bar 11, the separate shield 27, and the circuit board 8 in this order on the bottom wall 4c from the open side of the housing 4, thereby improving the ease of assembly of the power converter 1. Furthermore, the assembly time of the power converter 1 can be shortened, thereby reducing the assembly cost of the power converter 1. Furthermore, while a shield formed solely by the inner wall 4b imposes manufacturing constraints on the shape of the inner wall 4b, providing the separate shield 27 can eliminate these manufacturing constraints. Since the manufacturing constraints of the separate shield 27 are eliminated and the shape of the separate shield 27 can be freely changed, other functions can be imparted to the separate shield 27. The other functions imparted to the separate shield 27 will be described in the modified example below.

[0078] The configuration of wiring space 28 is not limited to the configuration shown in Fig. 9. In the configuration shown in Fig. 9, the cutout portion 4b3 is provided in the inner wall 4b, but the cutout portion 4b3 may be provided in the separate shield 27. Also, a configuration may be adopted in which the separate shield 27 having the cutout portion 4b3 is abutted against the bottom wall 4c without providing the inner wall 4b.

[0079] The separate shield 27 is made of a metal material such as an aluminum alloy. The separate shield 27 is made, for example, by aluminum die-casting. The separate shield 27 abuts against the substrate surface of the substrate 8 at a portion opposite the bottom wall 4c. At least a portion of the separate shield 27 abuts against the inner wall 4b at the portion on the bottom wall 4c side, and is fixed to the inner wall 4b at multiple locations, for example, with screws. This fixation connects the separate shield 27 to the housing ground. The separate shield 27 is also connected to the substrate 8 at multiple locations, for example, with screws. Connecting the substrate 8 to the separate shield 27 can improve the vibration resistance and heat dissipation of the substrate 8.

[0080] The substrate 8 has a solid pattern on the substrate surface where the separate shield 27 abuts, and the separate shield 27 and the solid pattern are electrically connected. At least a portion of the solid pattern is connected to the housing ground. The filter circuit components 9 and the control and power circuit components 10 arranged inside the small chamber 16a are separated by the separate shield 27. Furthermore, a portion of the inner layer of the substrate 8 has a solid pattern connected to the solid pattern provided on the substrate surface, and the solid pattern on the inner layer is also connected to the housing ground.

[0081] <Variation 1> A variation of the separate shield 27 will be described with reference to FIG. 10 . The separate shield 27 has an extension 27a extending from the main body of the shield along the surface of the substrate 8. The extension 27a is disposed between and separates multiple other circuit components. These circuit components are control and power circuit components 10. In this embodiment, the extension 27a separates the control and power circuit components 10a, 10b. By providing the extension 27a and increasing the contact area of ​​the separate shield 27 with the substrate 8, cooling of the substrate 8 can be enhanced. Heat transfer to components disposed on the substrate 8 can also be suppressed. Furthermore, the vibration resistance of the substrate 8 and the components disposed on the substrate 8 can be improved. Furthermore, because the extension 27a is disposed between and separates multiple control and power circuit components 10, the influence of noise between the components disposed on the substrate 8 can be reduced. In this embodiment, the main body and extension 27a of the separate shield 27 are integrated, but this is not limited to this. The main body and extension 27a may be formed separately and connected to each other.

[0082] The power conversion device 1 may have the following configuration. At least some of the filter circuit components 9 and the control and power circuit components 10 are thermally connected to the shield via a heat conductive member. In this embodiment, the control and power circuit component 10a is thermally connected to an extension 27a of the separate shield 27 via a heat conductive member 29a. The heat conductive member 29a is, for example, thermal grease. With this configuration, a path for heat dissipation from the components arranged on the board 8 is formed, thereby improving the heat dissipation performance of the components arranged on the board 8.

[0083] The power conversion device 1 may further include the following configuration. At least some of the filter circuit components 9 and the control and power circuit components 10 are fixed to the shield with adhesive 29b. In this embodiment, the control and power circuit components 10b are fixed to the extension portion 27a of the separate shield 27, which serves as a shield, with adhesive 29b. With this configuration, the components arranged on the substrate 8 are fixed to the extension portion 27a with adhesive, thereby improving the vibration resistance of the components arranged on the substrate 8.

[0084] <Modification 2> Another modification of the separate shield 27 will be described with reference to FIGS. 11 and 12 . As shown in FIG. 12 , the separate shield 27 has an opposing extension 27 b that extends from a portion of the shield's main body opposite the substrate 8 toward the substrate surface of the substrate 8. The filter circuit component 9 is provided on the substrate surface on which the separate shield 27 is provided, and the opposing extension 27 b covers a portion of the filter circuit component 9 opposite the substrate surface. With this configuration, at least a portion of the substrate 8, the filter circuit component 9, the opposing extension 27 b, and the main bus bar 11 are stacked. This lengthens the noise propagation path to the filter circuit component 9, thereby reducing the effect of noise on the filter circuit component 9. Note that in this embodiment, the main body and the opposing extension 27 b of the separate shield 27 are integrated, but this is not limiting. The main body and the opposing extension 27 b of the separate shield 27 may be formed separately and connected to each other.

[0085] 10 , at least some of the filter circuit components 9 and the control and power circuit components 10 may be thermally connected to the opposing extension 27b of the separate shield 27 via a heat conductive member 29a. Also, at least some of the filter circuit components 9 and the control and power circuit components 10 may be fixed to the opposing extension 27b of the separate shield 27 with an adhesive 29b.

[0086] <Modification 3> Another modification of the separate shield 27 will be described with reference to Figures 13 and 14. In the configuration described in Modification 2, the influence of noise on the filter circuit components 9 can be reduced, so as shown in Figure 14, the inner wall 4b between the external power supply side terminal block 19 and the smoothing capacitor 6 may be eliminated. By eliminating the inner wall 4b, the smoothing capacitor 6, which is the main circuit unit 5, can be placed in the location where the inner wall 4b was previously located. This reduces wasted space and allows the power conversion device 1 to be made more compact. Furthermore, because the main bus bar 11 can be further shortened, loss in the bus bar 30 is suppressed and heat generation in the bus bar 30 can be reduced.

[0087] As shown in the modified example described above, by changing the shape of the separate shield 27 without being restricted by the housing 4, it is possible to easily accommodate changes in the external shape of the power conversion device 1 and changes in the connection position of the external interface while reducing the impact of noise on the filter circuit components 9, thereby shortening the design time and development man-hours for the power conversion device 1.

[0088] Third Embodiment A power conversion device 1 according to a third embodiment will now be described. Fig. 15 is a plan view showing an outline of the power conversion device 1, with the cover 18 removed from the power conversion device 1 and only the outline of the board 8 being shown to illustrate the component layout, and Fig. 16 is a cross-sectional view of the power conversion device 1 taken along the line H-H in Fig. 15, illustrating the area surrounding the branch busbar 12 at the line H-H. The power conversion device 1 according to the third embodiment has a configuration in which the filter circuit components 9 are provided at a position different from that of the first and second embodiments.

[0089] The power module 7 and the smoothing capacitor 6 are electrically connected by a main bus bar 11, and the filter circuit component 9 is provided adjacent to a portion of the peripheral wall surrounding the bottom surface of the smoothing capacitor 6 other than the side opposite to the power module 7 side, or adjacent to the power module 7. As shown in FIG. 15 , in this embodiment, the filter circuit component 9 is provided on the power module 7 side of the smoothing capacitor 6, adjacent to the power module 7. The external power supply connection portion 20 is also provided on the power module 7 side of the smoothing capacitor 6, adjacent to the power module 7. As shown in FIG. 16 , a portion of the main bus bar 11 is arranged to overlap the power module 7.

[0090] By arranging the filter circuit components 9 in this manner, the main busbars 11 can be concentrated around the power module main terminals 13a (not shown in FIG. 15 ) provided on the smoothing capacitor 6 side, which are the electrical connection points with the smoothing capacitor 6, thereby reducing the size of the main busbars 11. Because the main busbars 11 are reduced in size, the loss, heat generation, and costs of the main busbars 11 can be reduced. Because the main busbars 11 are reduced in size and heat generation, heat damage from the main busbars 11 to components around the main busbars 11, such as the control and power circuit components 10 provided on the board 8, can be reduced. Furthermore, the wiring of the portion of the main busbars 11 that passes through the inside of the smoothing capacitor 6 can be simplified and reduced in size, thereby reducing the size and costs of the smoothing capacitor 6.

[0091] The positive and negative busbar portions are arranged to face at least a portion of the internal wiring 34 of the power module 7. As shown in FIG. 16 , in this embodiment, the positive main busbar 11a, which is the positive busbar portion, and the negative main busbar 11b, which is the negative busbar portion, are arranged to face the internal wiring 34. The internal wiring 34 is formed, for example, from a busbar, and the main surfaces of the busbar face the positive main busbar 11a and the negative main busbar 11b. The facing positive and negative busbar portions are parallel plate portions so that the current flows in opposite directions when a high-frequency current is applied. Similarly, the positive and negative busbar portions are parallel plate portions so that the current flows in opposite directions when a high-frequency current is applied.

[0092] By forming the parallel plate portions in this manner, the magnetic flux generated in the main busbar 11 and the internal wiring 34 is concentrated inside the main busbar 11 and the internal wiring 34, thereby reducing the high-frequency resistance of the main busbar 11 and the internal wiring 34 and thereby reducing heat loss generated in the main busbar 11 and the internal wiring 34. Furthermore, the magnetic flux generated in the main busbar 11 and the internal wiring 34 can be canceled outside the main busbar 11 and the internal wiring 34, thereby suppressing the generation of parasitic inductance. Furthermore, because the opposing surfaces of the opposing main busbar 11 and the internal wiring 34 are covered by the opposing portions, there are no open portions and noise coupling is less likely to occur.

[0093] Although the example shown is one in which the filter circuit component 9 is provided on the power module 7 side of the smoothing capacitor 6, adjacent to the power module 7, the arrangement of the filter circuit component 9 is not limited to this. The filter circuit component 9 may be provided above or below the smoothing capacitor 6, or between the smoothing capacitor 6 and the power module 7, as shown in Fig. 15. Even when the filter circuit component 9 is provided in such a position, the main bus bars 11 can be concentrated around the power module main terminals 13a, which are the electrical connection parts with the smoothing capacitor 6, and therefore the same effect as that described above can be obtained.

[0094] The external power supply connection unit 20 and the external power supply side terminal block 19 are provided adjacent to the power module 7 on the power module 7 side of the smoothing capacitor 6, similar to the filter circuit component 9, but the arrangement of the external power supply connection unit 20 and the external power supply side terminal block 19 is not limited to this. As with the filter circuit component 9, the external power supply connection unit 20 and the external power supply side terminal block 19 may be provided in a space above or below the smoothing capacitor 6 and the power module 7 in Fig. 15. This configuration makes it possible to easily accommodate changes in the external shape of the power conversion device 1 and changes in the connection position of the external interface, thereby reducing the time required for designing and the number of steps required for development of the power conversion device 1.

[0095] In this embodiment, the separate shield 27 having the opposing extensions 27b shown in the second embodiment is provided, but the configuration around the filter circuit component 9 is not limited to this. As shown in the first embodiment, the shield may be formed by the inner wall 4b.

[0096] Furthermore, the configurations shown in Embodiments 2 and 3 may also be provided with the additional shield 26 shown in Embodiment 1. By providing the additional shield 26, it is possible to block and suppress noise propagating to the filter circuit components 9 on both the side of one surface 8 a and the side of the other surface 8 b of the substrate 8, thereby reducing the effect of noise on the filter circuit components 9.

[0097] Although various exemplary embodiments and examples are described in this disclosure, the various features, aspects, and functions described in one or more embodiments are not limited to the application of a particular embodiment, but may be applied to the embodiments alone or in various combinations. Therefore, countless variations not illustrated are anticipated within the scope of the technology disclosed in this specification. For example, this includes cases where at least one component is modified, added, or omitted, or where at least one component is extracted and combined with components of another embodiment.

[0098] REFERENCE SIGNS LIST 1 power conversion device, 2 external power supply, 3 load, 4 housing, 4a outer wall, 4a1 outer wall through-hole, 4b inner wall, 4b1 inner wall through-hole, 4b2 boss, 4b3 notch, 4c bottom wall, 5 main circuit section, 6 smoothing capacitor, 6a capacitor element, 6b capacitor case, 7 power module, 7a power semiconductor element, 8 substrate, 8a one side, 8b other side, 9 filter circuit components, 10, 10a, 10b control and power circuit components, 11 main bus bar, 11a positive side main bus bar, 11b negative side main bus bar, 11c capacitor main bus bar, 12 branch bus bar, 12a positive side branch bus bar, 12b negative side branch bus bar, 13a, 13b power module main terminal, 14 power module terminal, 15 control wiring, 16a, 16b Small compartment, 17 refrigerant flow path, 18 cover, 19 external power supply side terminal block, 20 external power supply connection portion, 21 external power supply bus bar, 21a positive side external power supply bus bar, 21b negative side external power supply bus bar, 22 load connection portion, 23 load connection bus bar, 24 load side terminal block, 25 external device connection portion, 26 additional shield, 27 separate shield, 27a extension portion, 27b opposing extension portion, 28 wiring space, 29a heat conductive member, 29b adhesive, 30 bus bar, 31 external device, 32 housing ground pattern, 33 inner layer housing ground pattern, 34 internal wiring

Claims

1. A power conversion device comprising: a substrate provided with filter circuit components having one or more capacitors that remove noise; a power module having power semiconductor elements; and main circuit wiring connected to the power module, at least a portion of the main circuit wiring consisting of bus bars, the bus bars including a main bus bar that constitutes the main circuit wiring and branch bus bars branching from the main bus bar, the branch bus bars being electrically connected to the substrate.

2. The power conversion device according to claim 1, wherein the branch bus bar is connected to wiring on the board adjacent to the filter circuit component, and is electrically connected to the filter circuit component via the wiring on the board.

3. A power conversion device according to claim 1 or 2, wherein the substrate is disposed opposite the power module and the main circuit wiring with a gap therebetween, and the branch bus bar extends from the main bus bar of the main circuit wiring toward the substrate and is electrically connected to the filter circuit components via the wiring of the substrate.

4. A power conversion device according to any one of claims 1 to 3, further comprising: a housing having a bottom wall and accommodating said substrate and said power module; and a smoothing capacitor arranged alongside said power module along said bottom wall, wherein said filter circuit components are provided in a position adjacent to a portion of a peripheral wall surrounding the bottom surface of said smoothing capacitor on the side opposite to said power module.

5. A power conversion device according to any one of claims 1 to 3, further comprising: a housing having a bottom wall and accommodating said substrate and said power module; and a smoothing capacitor arranged alongside said power module along said bottom wall, said power module and said smoothing capacitor being electrically connected by said main bus bar, and said filter circuit components being provided in a position adjacent to a portion of a peripheral wall surrounding the bottom surface of said smoothing capacitor other than on the side opposite to said power module, or in a position adjacent to said power module.

6. A power conversion device according to any one of claims 1 to 5, further comprising a shield that is grounded in contact with the substrate and provided adjacent to the filter circuit component, the shield being disposed between the filter circuit component and one or more other circuit components provided on the substrate, and separating the filter circuit component from the other circuit components.

7. The power conversion device according to claim 6, wherein the shield is disposed between the other circuit components and the filter circuit components and the branch bus bar, and separates the other circuit components from the filter circuit components and the branch bus bar.

8. A power conversion device according to claim 6 or 7, further comprising a housing having a bottom wall and accommodating the substrate and the power module, the housing having an inner wall that is a part of the housing protruding from a part of the bottom wall inside the housing, the inner wall forming the shield, the inner wall having a through hole, and the main bus bar passing through the through hole.

9. A power conversion device according to claim 6 or 7, further comprising a housing having a bottom wall and accommodating the substrate and the power module, wherein a portion of the shield opposite to a portion that abuts against the substrate and is grounded abuts against the housing except for at least the wiring arrangement portion, the main bus bar passes through the space of the wiring arrangement portion, and the portion of the main bus bar that passes through the space, the shield, and the substrate are arranged in order in a direction away from the bottom wall.

10. A power conversion device according to any one of claims 6 to 9, further comprising a housing having a bottom wall and accommodating the substrate and the power module, wherein the bus bar comprises an external power supply bus bar connected to an external power source, the external power supply bus bar being connected to the main bus bar inside the housing, and the branch bus bar, the filter circuit components, and the shield being provided adjacent to the connection between the external power supply bus bar and the main bus bar.

11. A power conversion device according to any one of claims 6 to 10, further comprising a housing having a bottom wall and accommodating the substrate and the power module, the substrate having a wiring pattern on the substrate surface where the shield abuts, the shield and the wiring pattern being electrically connected, and at least a portion of the wiring pattern being a housing ground pattern connected to the housing.

12. The power conversion device according to claim 11, wherein the substrate is a multi-layer substrate, and an inner layer of the substrate has an inner-layer chassis ground pattern connected to the chassis ground pattern.

13. A power conversion device according to any one of claims 6 to 12, wherein the power module, the bus bar, and the shield are provided on one side of the substrate, and the power module is covered by the substrate.

14. A power conversion device as described in claim 13, further comprising a bottomed cylindrical housing having a bottom wall and accommodating the substrate and the power module, one surface of the substrate facing the bottom wall, the power module, the shield, and the filter circuit components being arranged in this order along the bottom wall, and the shield separating the power module and the filter circuit components.

15. A power conversion device according to any one of claims 6 to 14, further comprising: a housing having a bottom wall and accommodating the substrate and the power module, wherein the shield is provided on one side of the substrate; and an additional shield abutting the other side of the substrate and grounded to the substrate and the housing, wherein at least a portion of the additional shield is stacked on the shield via the substrate.

16. A power conversion device according to any one of claims 9 to 15, wherein the shield has an extension extending from the main body of the shield along the surface of the substrate, and the extension is disposed between a plurality of the other circuit components and separates the plurality of the other circuit components.

17. A power conversion device as claimed in any one of claims 9 to 16, wherein the shield has an opposing extension extending from a portion of the main body of the shield opposite the side of the substrate toward the substrate surface of the substrate, the filter circuit components are provided on the substrate surface on which the shield is provided, and the portion of the filter circuit components opposite the side of the substrate surface is covered by the opposing extension.

18. A power conversion device according to any one of claims 9 to 17, wherein at least some of the filter circuit components and the other circuit components are thermally connected to the shield via a heat conductive member.

19. A power conversion device according to any one of claims 9 to 18, wherein at least some of the filter circuit components and the other circuit components are fixed to the shield with an adhesive.

20. A power conversion device according to any one of claims 1 to 19, wherein the main busbar and the branch busbars are composed of a positive busbar portion and a negative busbar portion, and at least a portion of the positive busbar portion and the negative busbar portion are arranged opposite each other.

21. The power conversion device according to claim 20, wherein the positive bus bar portion and the negative bus bar portion are arranged opposite at least a portion of the internal wiring of the power module.

22. A power conversion device according to any one of claims 1 to 21, wherein the capacitor included in the filter circuit component is one or both of an X capacitor and a Y capacitor.

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