Inverter

Abstract

To provide an inverter capable of suppressing a surge voltage generated during switching operation.SOLUTION: An inverter includes a power substrate, a switching element, a bus bar, and a capacitor substrate. The switching elements are mounted on the first main surface of the power board and are classified into a positive electrode side and a negative electrode side. The bus bar is provided on a second main surface of the power board, which is a back side of the first main surface, and electrically connected to the switching element. The capacitor substrate is stacked on the bus bar, the capacitor is mounted on a surface of the capacitor substrate opposite to the bus bar, and the capacitor and the switching element are electrically connected to each other via the bus bar. At least one of the positive electrode side and the negative electrode side of the switching element is mounted in a direction not parallel to a current direction of a current path connecting the positive electrode side and the negative electrode side when viewed in the stacking direction.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an inverter. [Background technology]

[0002] Conventionally, in inverters, a technology has been known in which a heat sink is brought into contact with the back side of a substrate on which heat-generating elements such as switching elements are mounted, thereby dissipating heat generated by the heat-generating elements through the substrate (see, for example, Patent Document 1).

[0003] Another conventional method for preventing the temperature of switching elements from rising is to reduce the electrical resistance of the switching elements, which reduces power loss during switching operations by reducing the electrical resistance, thereby suppressing heat generation in the switching elements. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-195374 Summary of the Invention [Problem to be solved by the invention]

[0005] However, since switching elements with low electrical resistance tend to have low guaranteed voltages, there is a risk that surge voltages generated during switching operations may exceed the guaranteed voltages.

[0006] The present invention has been made in view of the above, and has an object to provide an inverter capable of suppressing surge voltages that occur during switching operations. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems and achieve the object, the inverter of the present invention includes a power board, a plurality of switching elements, a bus bar, and a capacitor board. The plurality of switching elements are mounted on a first main surface of the power board and are classified as either positive or negative. The bus bar is provided on a second main surface of the power board, which is the reverse side of the first main surface, and is electrically connected to the switching elements. The capacitor board is a capacitor board that is stacked on the bus bar, and capacitors are mounted on the surface opposite to the bus bar, and the capacitors and the switching elements are electrically connected via the bus bar. At least one of the positive and negative side switching elements is mounted in an orientation that is not parallel to the current direction of a current path connecting the positive and negative sides when viewed in the stacking direction. [Effects of the Invention]

[0008] According to the present invention, by arranging the switching elements, bus bars, and capacitors in the stacking direction, the length of the paths connecting the switching elements, bus bars, and capacitors in the circuit can be shortened. Furthermore, by mounting at least one of the positive and negative sides of the switching elements in an orientation that is not parallel to the current direction of the current path connecting the positive and negative sides when viewed in the stacking direction, the length of the paths connecting the switching elements, bus bars, and capacitors in the circuit can be shortened compared to when the current direction of at least one of the positive and negative sides of the switching elements is parallel to the current direction of the current path. This reduces the parasitic inductance of the paths through which current flows during switching operations, thereby suppressing surge voltages that occur during switching operations. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is an exploded perspective view of an inverter according to an embodiment. [Figure 2] FIG. 2 is a plan view of the first main surface side of the power board. [Figure 3]FIG. 3 is a plan view of the second main surface side of the power board. [Figure 4] FIG. 4 is a cross-sectional view of the inverter. [Figure 5] FIG. 5 is a diagram for explaining a path through which a current flows in the inverter. [Figure 6] FIG. 6 is a diagram for explaining paths through which current flows in the inverter. DETAILED DESCRIPTION OF THE INVENTION

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An inverter according to an embodiment will be described in detail below with reference to the accompanying drawings. However, the present invention is not limited to the following embodiments.

[0011] Fig. 1 is an exploded perspective view of an inverter 1 according to an embodiment. Fig. 2 is a plan view of a first main surface 3a of a power board 3. Fig. 3 is a plan view of a second main surface 3b of the power board 3. Fig. 4 is a cross-sectional view of the inverter 1 taken along line AA in Fig. 2. Note that Fig. 1 shows part of the internal structure of the inverter 1, with some components such as a housing omitted, for example.

[0012] 1 to 3, the inverter 1 is arranged by stacking a capacitor substrate 2, a power substrate 3, and a heat sink 4. Specifically, the inverter 1 is stacked in a position where the power substrate 3 is sandwiched between the capacitor substrate 2 and the heat sink 4.

[0013] The capacitor substrate 2 is a resin substrate on which a conductive pattern 20 is formed on the surface opposite to the power substrate 3 and on which a capacitor 21 is mounted. The conductive pattern 20 is made of a metal member such as copper, and includes a first pattern 20a corresponding to the positive electrode and a second pattern 20b corresponding to the negative electrode. The first pattern 20a and the second pattern 20b are each formed in a shape (a rectangular shape in FIG. 1) that extends in the longitudinal direction of the capacitor substrate 2 with a predetermined gap between them. The first pattern 20a and the second pattern 20b are also arranged on the back side of the capacitor substrate 2 (the side facing the power substrate 3).

[0014] The capacitor substrate 2 is also provided with through holes 2a and 2b into which fastening members 100 (see FIG. 4) described later are inserted. Specifically, a plurality of through holes 2a are provided in the area of ​​the first pattern 20a of the capacitor substrate 2, and a plurality of through holes 2b are provided in the area of ​​the second pattern 20b.

[0015] The capacitor 21 is a smoothing capacitor electrically connected to the first pattern 20a and the second pattern 20b and smoothes current input from the outside. A plurality of capacitors 21 are provided, and are arranged in a row along the longitudinal direction of the capacitor substrate 2 between the first pattern 20a and the second pattern 20b. The first pattern 20a and the second pattern 20b are arranged in positions overlapping the first bus bar 31 and the second bus bar 32, respectively, in the stacking direction. That is, the capacitor 21 is arranged in a position sandwiched between the first bus bar 31 and the second bus bar 32 as viewed in the stacking direction. This shortens the distance from the capacitor 21 to each of the first bus bar 31 and the second bus bar 32, thereby shortening the path R (see FIG. 5 ), which will be described later. That is, the inverter 1 can reduce the parasitic inductance of the path R, through which current flows during switching operations, thereby suppressing surge voltages that occur during switching operations.

[0016] Although the plurality of capacitors 21 are arranged in a line in the example shown in FIG. 1, the plurality of capacitors 21 may be arranged densely between the first pattern 20a and the second pattern 20b in a staggered arrangement or the like.

[0017] The power board 3 is a resin board on which electronic components related to current conversion are mounted. The power board 3 has a first bus bar 31, a second bus bar 32, and a power element 33 mounted thereon.

[0018] The first bus bar 31 is a columnar metal member mounted on the second main surface 3b of the power board 3. Specifically, the first bus bar 31 is mounted in contact with (electrically connected to) the first conductive pattern 310b formed on the second main surface 3b. The first bus bar 31 is also electrically connected to the first pattern 20a via the surface of the capacitor board 2 opposite to the capacitors 21. The first bus bar 31 is also provided with through holes 31a into which fastening members 100 (see FIG. 4), which will be described later, are inserted.

[0019] The second bus bar 32 is a columnar metal member mounted on the second main surface 3b of the power board 3. Specifically, the second bus bar 32 is mounted in contact with (electrically connected to) the second conductive pattern 320b formed on the second main surface 3b. The second bus bar 32 is also electrically connected to the second pattern 20b via the surface of the capacitor substrate 2 opposite to the capacitors 21. The second bus bar 32 is also provided with through holes 32a into which fastening members 100 (see FIG. 4), which will be described later, are inserted.

[0020] The power elements 33 are switching elements formed of semiconductors such as transistors. The power elements 33 are mounted on the first main surface 3a of the power board 3. Specifically, the power elements 33 are composed of a plurality of first power elements 33a on the positive side and a plurality of second power elements 33b on the negative side. As shown in FIG. 2, one terminal of each of the first power elements 33a is connected to the first conductive pattern 310a, and the other terminal is connected to the third conductive pattern 330a. More specifically, one end of the first power element 33aW is connected to the third conductive pattern 330aW corresponding to the W-phase of a three-phase AC current (U-phase, V-phase, and W-phase). Furthermore, one end of the first power element 33aV is connected to the third conductive pattern 330aV corresponding to the V-phase. Furthermore, one end of the first power element 33aU is connected to the third conductive pattern 330aU corresponding to the U-phase. The second power element 33b has one terminal connected to the second conductive pattern 320a and the other terminal connected to the third conductive pattern 330a. More specifically, the second power element 33bW has one end connected to the third conductive pattern 330aW corresponding to the W phase. The second power element 33bV has one end connected to the third conductive pattern 330aV corresponding to the V phase. The second power element 33bU has one end connected to the third conductive pattern 330aU corresponding to the U phase. In other words, the first power element 33a is a switching element classified as being on the positive side of the power supply, and the second power element 33b is a switching element classified as being on the negative side of the power supply.

[0021] The first conductive pattern 310a is electrically connected to the first conductive pattern 310b on the second main surface 3b via a through hole. The second conductive pattern 320a is electrically connected to the second conductive pattern 320b on the second main surface 3b via a through hole. The third conductive pattern 330a is electrically connected to the third conductive pattern 330b on the second main surface 3b via a through hole. Specifically, the third conductive pattern 330aW on the first main surface 3a is connected to the third conductive pattern 330bW on the second main surface 3b. The third conductive pattern 330aV on the first main surface 3a is connected to the third conductive pattern 330bV on the second main surface 3b. The third conductive pattern 330aU on the first main surface 3a is connected to the third conductive pattern 330bU on the second main surface 3b.

[0022] The first conductive patterns 310a and 310b are provided with through holes 310a1 into which an input electrode corresponding to a positive electrode is inserted. As a result, the positive input electrode is electrically connected to the capacitor 21 and the power element 33 via the first conductive patterns 310a and 310b. The second conductive patterns 320a and 320b are provided with through holes 320a1 into which an input electrode corresponding to a negative electrode is inserted. As a result, the negative input electrode is electrically connected to the capacitor 21 and the power element 33 via the second conductive patterns 320a and 320b. The third conductive patterns 330a and 330b are provided with through holes 330a1 into which output electrodes corresponding to each phase of a three-phase AC current are inserted. As a result, the output electrodes of each phase are electrically connected to the capacitor 21 and the power element 33 via the third conductive patterns 330a and 330b.

[0023] Further, in the region of the first conductive patterns 310a and 310b, there are provided through holes 310a2 into which fastening members 100, which will be described later, are inserted. Further, in the region of the second conductive patterns 320a and 320b, there are provided through holes 320a2 into which fastening members 100, which will be described later, are inserted.

[0024] 2, the first power element 33a is disposed such that the direction of current flowing through the first power element 33a (horizontal direction in the drawing) is not parallel to the direction of current flowing through the third conductive pattern 330a (vertical direction in the drawing) when viewed in the stacking direction (perpendicular direction in FIG. 2). This allows the distance between the first conductive pattern 310a and the second conductive pattern 320a to be narrower than when the first power element 33a is disposed parallel to the direction of current flowing through the third conductive pattern 330a. Narrowing the distance between the first conductive pattern 310a and the second conductive pattern 320a narrows the distance between the first pattern 20a and the second pattern 20b of the capacitor substrate 2, thereby shortening the path R (see FIG. 5), which will be described later. In other words, the inverter 1 can reduce the parasitic inductance of the path R through which current flows during switching operations, thereby suppressing surge voltages that occur during switching operations.

[0025] As shown in FIG. 2, the first power elements 33a are provided on the first principal surface 3a at the same position as the first bus bar 31 provided on the second principal surface 3b. In other words, the first bus bar 31 is disposed so as to overlap the first power elements 33a when viewed in the stacking direction. The second power elements 33b are provided on the first principal surface 3a at the same position as the second bus bar 32 provided on the second principal surface 3b. In other words, the second bus bar 32 is disposed so as to overlap the second power elements 33b in the stacking direction. This allows the bus bar and the power elements 33 to be connected over the shortest distance, thereby shortening the path R (see FIG. 5), which will be described later. In other words, the inverter 1 can reduce the parasitic inductance of the path R, through which current flows during switching operations, thereby suppressing surge voltages that occur during switching operations. Furthermore, heat generated by the power elements 33 may cause the surrounding power boards 3 to become easily deformed, but by arranging the bus bar and the power elements 33 in a position where they overlap when viewed in the stacking direction, deformation of the power boards 3 can be prevented. In other words, because the bus bar is a metal member, the portions of the power boards 3 that are in contact with the bus bar are fixed by the bus bar and are therefore less likely to deform. As a result, even if heat generated by the power elements 33 causes the power boards 3 around the power elements 33 to become easily deformed, deformation of the power boards 3 can be prevented by arranging the bus bar and the power elements 33 in a position where they overlap when viewed in the stacking direction.

[0026] The heat sink 4 is stacked on the first main surface 3a side of the power board 3. Specifically, the heat sink 4 is disposed in a position facing the power elements 33 mounted on the first main surface 3a when viewed in the stacking direction. Specifically, as shown in FIG. 4 , the heat sink 4 contacts the power elements 33 via an insulating member 34. More specifically, the heat dissipation portion 340 of the power elements 33 contacts the insulating member 34. In other words, the power elements 33 have the heat dissipation portion 340 provided in a position facing the heat sink 4. This allows the power elements 33 to dissipate heat generated during switching operation via the heat dissipation portion 340 and the heat sink 4.

[0027] 1, the surface of the heat sink 4 facing the power board 3 is provided with recesses 4a and 4b into which a fastening member 100, which will be described later, is inserted. Specifically, as shown in Fig. 1, the recess 4a is arranged at a position overlapping in the stacking direction with the through hole 2a of the capacitor board 2, the through hole 31a of the first bus bar 31, and the through hole 310a2 of the first conductive pattern 310a. The recess 4b is arranged at a position overlapping in the stacking direction with the through hole 2b of the capacitor board 2, the through hole 32a of the second bus bar 32, and the through hole 320a2 of the second conductive pattern 320a.

[0028] 4, the fastening member 100 is inserted into the through hole 2b, the through hole 32a, the through hole 320a2, and the recess 4b and fastened. Similarly, although not shown, another fastening member 100 is inserted into the through hole 2a, the through hole 31a, the through hole 310a2, and the recess 4a and fastened. In other words, the fastening member 100 fastens the capacitor board 2, the power board 3, and the heat sink 4 together. This allows the number of fastening members 100 to be reduced, thereby reducing the number of parts.

[0029] 4 , the second bus bar 32 generates a pressing force from the capacitor substrate 2 to the power substrate 3 due to the fastening force of the fastening member 100, and this pressing force enables the power substrate 3 to press the power elements 33 against the heat sink 4. This allows the heat dissipation portion 340 of the power elements 33 to be firmly attached to the heat sink 4, thereby enabling efficient transfer of heat from the heat dissipation portion 340 to the heat sink 4. In other words, the heat generated in the power elements 33 can be efficiently dissipated in the heat sink 4.

[0030] Next, the path through which current flows will be described with reference to Fig. 5 and Fig. 6. Fig. 5 and Fig. 6 are diagrams for explaining the path R through which current flows in the inverter 1. Fig. 5 shows a cross-sectional view taken along line BB in Fig. 2, and Fig. 6 shows a circuit diagram for supplying current from the inverter 1 to the motor M.

[0031] 6, the power line connecting the positive electrode side of the power supply to the first power elements 33aW, 33aV, and 33aU corresponds to the first bus bar 31 and the first conductive pattern 310a. The power line connecting the negative electrode side of the power supply to the second power elements 33bW, 33bV, and 33bU corresponds to the second bus bar 32 and the second conductive pattern 320a. The power line connecting the positive electrode side and the negative electrode side of the power supply and having the capacitor 21 provided thereon corresponds to the conductive pattern 20 provided on the capacitor substrate 2. The power line (current path) connecting the first power elements 33aW, 33aV, and 33aU and the second power elements 33bW, 33bV, and 33bU and connected to the power supply line to the motor M corresponds to the third conductive patterns 330aW, 330aV, and 330aU.

[0032] 5, in inverter 1, a path R through which a current flows is formed by power element 33, first bus bar 31, second bus bar 32, and capacitor 21. Specifically, in inverter 1, a path R is formed that passes through capacitor 21, first bus bar 31, first power element 33a, second power element 33b, and second bus bar 32. That is, as in the circuit diagram shown in FIG. 6, a path R is formed that passes through capacitor 21, first power element 33a, and second power element 33b.

[0033] To configure such a path R, in the present disclosure, the power elements 33, the bus bars (first bus bar 31 and second bus bar 32), and the capacitors 21 are arranged in the stacking direction. This shortens the distance between the power elements 33, the bus bars, and the capacitors 21, thereby shortening the path R that forms the circuit connecting the power elements 33, the bus bars, and the capacitors 21. Therefore, according to the present disclosure, the parasitic inductance of the path R, through which current flows during switching operation, can be reduced, thereby suppressing surge voltages that occur during switching operation.

[0034] Although the circuit diagram in FIG. 6 illustrates one each of the first power elements 33aW, 33aV, and 33aU and the second power elements 33bW, 33bV, and 33bU, in practice, as shown in FIG. 2 and other figures, the first power elements 33aW, 33aV, and 33aU and the second power elements 33bW, 33bV, and 33bU are each composed of two power elements to accommodate the amount of current flowing through the circuit. The number of power elements for each phase is not limited to two. For example, if the amount of current flowing through the circuit is increased to increase the output of the motor M, the number of power elements for each phase may be three or more. When increasing the number of power elements, it is preferable to increase the number by a multiple of two to accommodate the explanation below.

[0035] Furthermore, in the present disclosure, one of the power line on the positive side of the power supply (first bus bar 31 and first conductive pattern 310a) and the power line on the negative side (second bus bar 32 and second conductive pattern 320a) can be configured to be connected to a power line (third conductive patterns 330aW, 330aV, 330aU) that is connected to a power supply line to the motor M. That is, in the above embodiment, an example is shown in which the power line on the positive side of the power supply is connected to the power line connected to the motor M, but the power line on the positive side and the power line on the negative side of the power supply may be swapped, and the power line on the negative side of the power supply may be connected to the power line connected to the motor M.

[0036] In the above embodiment, the positive power line of the power supply, which is connected to the power line connected to the motor M, is provided with a first bus bar 31 that is arranged parallel to the negative power line of the power supply. The first conductive pattern 310a, the third conductive patterns 330aW, 330aV, 330aU, and the first power elements 33aW, 33aV, 33aU on the positive side of the power supply are arranged along the first bus bar 31 (so as to be aligned with the position where the first bus bar 31 is arranged on the first main surface 3a, which is the back side of the second main surface 3b on which the first bus bar 31 is arranged). Specifically, the two transistors constituting the first power elements 33aW, 33aV, and 33aU are connected to the first conductive pattern 310a and the third conductive patterns 330aW, 330aV, and 330aU on the positive side of the power supply, so that the two transistors are commonly connected to the same conductive pattern for the third conductive patterns 330aW, 330aV, and 330aU, but the first conductive pattern 310a on the positive side of the power supply is connected to a first conductive pattern 310a provided in a different location. Note that at least one of the two transistors constituting each of the first power elements 33aW, 33aV, and 33aU is connected to the same first conductive pattern 310a as the transistor of the first power element 33aW, 33aV, and 33aU of a different phase.

[0037] In the above-described embodiment, the first power elements 33aW, 33aV, and 33aU on the high side and the second power elements 33bW, 33bV, and 33bU on the low side are arranged to face in different directions (intersecting directions) so that the power lines on the positive and negative sides of the power supply are arranged parallel to each other. Specifically, the first power elements 33aW, 33aV, and 33aU are arranged side by side in the longitudinal direction of the power board 3 so that their connection terminals with the conductive patterns face the longitudinal direction of the power board 3, and the second power elements 33bW, 33bV, and 33bU are arranged side by side in the longitudinal direction so that their connection terminals with the conductive patterns face the lateral direction of the power board 3. In other words, the two transistors constituting the first power elements 33aW, 33aV, and 33aU corresponding to each phase are mounted in pairs so that their current directions (directions toward the third conductive pattern 330a) face each other. By using such an arrangement, the positional relationship between the power line on the positive side of the power supply, the power line on the negative side of the power supply, and the power line connected to the motor M can be made closer, and since the power line on the positive side of the power supply and the power line on the negative side of the power supply are configured to be connected to the capacitor board 2 via the first bus bar 31 and the second bus bar 32, the physical distance of the closed circuits of each phase of the W phase, V phase, and U phase shown in Figure 6 can be shortened.

[0038] Although not shown, the power line on the positive side of the power supply and the power line on the negative side of the power supply are provided with external terminals for connection to an external power supply, and the power line connected to the motor M is provided with an external terminal for connection to an external motor M.

[0039] Further advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described above. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents. [Explanation of symbols]

[0040] 1 inverter 2 Capacitor board 3 Power Board 4 Heatsink 21 Capacitor 31 First bus bar 32 Second bus bar 33 Power Elements 33a First power element 33b Second power element 34 Insulating material 100 Fastening member 340 Heat dissipation part Medium motor R pathway

Claims

1. A power board, a plurality of switching elements mounted on a first main surface of the power board, each of which is classified as a positive electrode side or a negative electrode side; a bus bar provided on a second main surface of the power board, the second main surface being a rear side of the first main surface, and electrically connected to the switching element; a capacitor substrate that is laminated on the bus bar, the capacitor being mounted on a surface opposite to the bus bar, and electrically connecting the capacitor and the switching element via the bus bar; Equipped with At least one of the positive and negative sides of the switching element is The positive electrode side and the negative electrode side are mounted in a direction that is not parallel to the current direction of the current path connecting the positive electrode side and the negative electrode side when viewed in the stacking direction. Inverter.

2. The bus bar is The switching element is disposed at a position overlapping the switching element when viewed in the stacking direction. The inverter according to claim 1 .

3. The bus bar is a first columnar bus bar corresponding to the positive electrode and a second columnar bus bar corresponding to the negative electrode; The capacitor is The bus bar is disposed at a position sandwiched between the first bus bar and the second bus bar when viewed in the stacking direction. The inverter according to claim 1 .

4. The switching element further includes a heat sink in contact with the switching element. The inverter according to claim 1 .

5. The heat sink is The switching element is disposed at a position opposite to the switching element when viewed in the stacking direction. The inverter according to claim 4 .

6. The switching element is a heat dissipation portion provided at a position facing the heat sink; The inverter according to claim 5 .

7. At least one of the positive and negative sides of the switching element is Includes pairs mounted so that the current flows in opposite directions The inverter according to claim 1 .

Images