Smoothing circuit

Abstract

To suppress a rise of a surge voltage while improving noise reduction performance.SOLUTION: A smoothing circuit (10) comprises: positive electrode wiring (11); negative electrode wiring (12); and a first capacitor part (C1) and a second capacitor part (C2) which are connected in parallel between the positive electrode wiring and the negative electrode wiring. The positive electrode wiring includes a first positive electrode connection part (P1) connected to the first capacitor part and a second positive electrode connection part (P2) connected to the second capacitor part, and the negative electrode wiring includes a first negative electrode connection part (N1) connected to the second capacitor part and a second negative electrode connection part (N2) connected to the first capacitor part. The positive electrode wiring and the negative electrode wiring intersect with each other in a three-dimensional manner. Inductance of the positive electrode wiring is substantially equal to equivalent series inductance of the first capacitor part, and inductance of the negative electrode wiring is substantially equal to equivalent series inductance of the second capacitor part. The smoothing circuit includes a snubber circuit (Cs) which is connected between the positive electrode wiring and the negative electrode wiring.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a smoothing circuit including a plurality of capacitors. [Background technology]

[0002] For example, there is a noise filter device that includes a positive wiring, a negative wiring, and a first capacitor and a second capacitor connected in parallel between the positive wiring and the negative wiring, where the positive wiring connects a first positive electrode connection part that connects to the first capacitor and a second positive electrode connection part that connects to the second capacitor, and the negative wiring connects a first negative electrode connection part that connects to the second capacitor and a second negative electrode connection part that connects to the first capacitor, and where the positive wiring and the negative wiring cross each other at an intersection (see Patent Document 1). In the noise filter device described in Patent Document 1, the inductance of the positive wiring and the negative wiring is made equal to the equivalent series inductance (ESL) of the first capacitor and the second capacitor, thereby canceling out the ESL of the first capacitor and the second capacitor and improving noise reduction performance. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-162441 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, when the noise filter device described in Patent Document 1 is connected between a DC power supply and a power conversion circuit, it can reduce noise transmitted from the power conversion circuit, which is a noise source, to the DC power supply. However, increasing the inductance of the positive and negative wiring to offset the ESL of the first and second capacitors increases the surge voltage applied to the power conversion circuit. In particular, in the configuration described in Patent Document 1, the first and second capacitors are connected crosswise to create an overpass between the positive and negative wiring, the inductance is doubled compared to when the first and second capacitors are simply connected in parallel. For this reason, the noise filter device described in Patent Document 1 significantly increases the surge voltage applied to the power conversion circuit, making it difficult to directly use it in a smoothing circuit connected between a DC power supply and a power conversion circuit, for example.

[0005] The present invention has been made to solve the above-mentioned problems, and its main object is to provide a smoothing circuit that can suppress an increase in surge voltage while improving noise reduction performance. [Means for solving the problem]

[0006] The first means for solving the above problem is: A smoothing circuit including a positive electrode wiring, a negative electrode wiring, and a first capacitor unit and a second capacitor unit connected in parallel between the positive electrode wiring and the negative electrode wiring, the positive wiring has a first positive electrode connection portion connected to the first capacitor portion and a second positive electrode connection portion connected to the second capacitor portion, the negative wiring has a first negative electrode connection portion connected to the second capacitor portion and a second negative electrode connection portion connected to the first capacitor portion, The positive electrode wiring and the negative electrode wiring cross each other at an intersection, the inductance of the positive wiring is substantially equal to the equivalent series inductance of the first capacitor section, the inductance of the negative wiring is substantially equal to the equivalent series inductance of the second capacitor section, A snubber circuit is provided connected between the positive wiring and the negative wiring.

[0007] According to the above configuration, a positive wiring having a first positive electrode connection portion connected to the first capacitor unit and a second positive electrode connection portion connected to the second capacitor unit intersects with a negative wiring having a first negative electrode connection portion connected to the second capacitor unit and a second negative electrode connection portion connected to the first capacitor unit. That is, the positive wiring and the negative wiring intersect on a plane projected in a predetermined first direction. The inductance of the positive wiring is substantially equal to the equivalent series inductance of the first capacitor unit, and the inductance of the negative wiring is substantially equal to the equivalent series inductance of the second capacitor unit. Therefore, the equivalent series inductances (hereinafter referred to as "ESL") of the first capacitor unit and the second capacitor unit can be offset by the inductances of the positive wiring and the negative wiring, respectively, thereby improving the noise reduction performance of the smoothing circuit.

[0008] Furthermore, since the smoothing circuit includes a snubber circuit connected between the positive wiring and the negative wiring, it is possible to suppress an increase in surge voltage applied between the positive wiring and the negative wiring. Therefore, the smoothing circuit in which the first capacitor unit and the second capacitor unit are cross-connected to form a three-dimensional intersection between the positive wiring and the negative wiring can be used, for example, as a smoothing circuit connected between a DC power source and a power conversion circuit. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 2 is a circuit diagram of a smoothing circuit according to the first embodiment. [Figure 2] FIG. 2 is a front view showing the structure of the smoothing circuit according to the first embodiment. [Figure 3] FIG. 3 is a plan view of the smoothing circuit of FIG. 2; [Figure 4] FIG. 2 is a plan view showing a case of the smoothing circuit according to the first embodiment. [Figure 5] FIG. 10 is a plan view showing a modified example of the structure of the smoothing circuit. [Figure 6]FIG. 6 is a circuit diagram of a smoothing circuit according to a second embodiment. [Figure 7] FIG. 10 is a front view showing the structure of a smoothing circuit according to a second embodiment. [Figure 8] FIG. 8 is a plan view of the smoothing circuit of FIG. 7; [Figure 9] 10 is a graph showing simulation results of surge peak voltages in a comparative example and the second embodiment. [Figure 10] FIG. 10 is a circuit diagram of a smoothing circuit according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] (First embodiment) Hereinafter, a first embodiment embodied in a smoothing circuit connected between a DC power supply and a power conversion circuit (inverter) will be described with reference to the drawings.

[0011] As shown in FIG. 1, the smoothing circuit 10 includes a positive electrode wiring 11, a negative electrode wiring 12, a first capacitor section C1, a second capacitor section C2, and a capacitor Cs.

[0012] A first capacitor section C1 and a second capacitor section C2 are connected in parallel between the positive electrode wiring 11 and the negative electrode wiring 12. The first capacitor section C1 is composed of, for example, two capacitors C11 connected in parallel (see FIGS. 2 and 3). The second capacitor section C2 is composed of, for example, two capacitors C21 connected in parallel (see FIGS. 2 and 3).

[0013] The positive electrode wiring 11 has a first positive electrode connection portion P1 connected to the first capacitor portion C1 and a second positive electrode connection portion P2 connected to the second capacitor portion C2. The negative electrode wiring 12 has a first negative electrode connection portion N1 connected to the second capacitor portion C2 and a second negative electrode connection portion N2 connected to the first capacitor portion C1. The positive electrode wiring 11 and the negative electrode wiring 12 intersect at an intersection. The structure for realizing this intersection will be described later.

[0014] The parasitic inductances of the first capacitor section C1 and the second capacitor section C2 are represented by equivalent series inductances Lc1 and Lc2, respectively. Furthermore, the inductance component of the positive wiring 11 between the first positive electrode connecting section P1 and the second positive electrode connecting section P2 (the inductance component of the positive electrode wiring 11) is represented by equivalent series inductance Lp. The inductance component of the negative wiring 12 between the first negative electrode connecting section N1 and the second negative electrode connecting section N2 (the inductance component of the negative electrode wiring 12) is represented by equivalent series inductance Ln. The inductance Lp is set equal (substantially equal) to the inductance Lc1. The inductance Ln is set equal (substantially equal) to the inductance Lc2. The inductance Lp may be substantially equal to the inductance Lc1, and may include a small error. The inductance Ln may be substantially equal to the inductance Lc2, and may include a small error.

[0015] The positive input terminal Pin and the negative input terminal Nin are connected to a switching element (not shown) of a power conversion circuit, which is a noise source. The positive output terminal Pout and the negative output terminal Nout are connected to a DC power supply (not shown). A capacitor Cs (C snubber circuit, snubber circuit) is connected between the portion of the positive wiring 11 between the second positive connection part P2 and the positive input terminal Pin, and the portion of the negative wiring 12 between the second negative connection part N2 and the negative input terminal Nin.

[0016] Here, let Cs be the capacitance of capacitor Cs, Lp be the inductance of positive wiring 11, I be the current flowing through positive wiring 11 when the switching element is turned off, and Vb be the allowable value of surge voltage. The allowable value Vb is set, for example, to be a predetermined voltage lower than the withstand voltage of the switching element of the power conversion circuit. In this case, if the electrostatic energy (1 / 2·Cs·Vb^2) that can be stored in capacitor Cs is made greater than the electromagnetic energy (1 / 2·Lp·I^2) stored in inductance Lp of positive wiring 11, the surge voltage can be made lower than the allowable value Vb. "b^2" represents the square of b. To achieve this, the following inequality (1) must be established. (1 / 2·Cs·Vb^2)>(1 / 2·Lp·I^2) ···(1) By transforming inequality (1), we can derive the following inequality (2). Cs>Lp(I / Vb)^2 (2) In this embodiment, the capacitance of the capacitor Cs is set so that the inequality (2) holds.

[0017] 2 and 3, the capacitors C11 and C12 are formed in an elongated cylindrical shape. The axial direction of the capacitors C11 and C12 (the vertical direction in FIG. 2) corresponds to the longitudinal direction of the capacitors C11 and C12. The arrangement direction of the capacitor sections C1 and C2 (the horizontal direction in FIG. 2 and 3) corresponds to the longitudinal direction of the smoothing circuit 10.

[0018] The positive electrode wiring 11 and the negative electrode wiring 12 cross each other at an intersection with the first capacitor unit C1 and the second capacitor unit C2 in between. That is, the positive electrode wiring 11 and the negative electrode wiring 12 cross each other on a projection plane in a direction (a predetermined first direction) perpendicular to the arrangement direction of the capacitor units C1 and C2 (the longitudinal direction of the smoothing circuit 10, the left-right direction in FIGS. 2 and 3) and the axial direction of the capacitors C11 and C12 (the longitudinal direction of the capacitors C11 and C12, the up-down direction in FIG. 2). The outer peripheral surfaces of the capacitors C11 and C12 are insulated from the positive electrode wiring 11 and the negative electrode wiring 12.

[0019] The first capacitor section C1 has a positive electrode C13 (first electrode) and a negative electrode C14 (second electrode). The second capacitor section C2 has a positive electrode C23 (first electrode) and a negative electrode C24 (second electrode). The first capacitor section C1 and the second capacitor section C2 are arranged so that the orientations of their positive and negative electrodes are opposite in the vertical direction (predetermined direction) of FIG. 2. For example, in the first capacitor section C1, the positive electrode C13 is arranged on the upper side and the negative electrode C14 is arranged on the lower side, whereas in the second capacitor section C2, the positive electrode C23 is arranged on the lower side and the negative electrode C24 is arranged on the upper side. The positive electrodes C13 and C23 of the capacitor sections C1 and C2 (respective capacitors C11 and C21) are connected to the positive wiring 11 by solder S. The negative electrodes C14 and C24 of the capacitor sections C1 and C2 (respective capacitors C11 and C12) are connected to the negative wiring 12 by solder S.

[0020] The positive electrode wiring 11 connects the positive electrode C13 of the first capacitor unit C1 and the positive electrode C23 of the second capacitor unit C2 obliquely to the vertical direction in Figure 2 (the axial direction of the capacitors C11 and C12, the predetermined direction). The negative electrode wiring 12 connects the negative electrode C14 of the first capacitor unit C1 and the negative electrode C24 of the second capacitor unit C2 obliquely to the vertical direction in Figure 2 (the axial direction of the capacitors C11 and C12, the predetermined direction).

[0021] The positive electrode wiring 11 and the negative electrode wiring 12 are formed by bus bars, which are, for example, copper (metal) plates. The inductance components of the positive electrode wiring 11 and the negative electrode wiring 12 can be controlled by adjusting the length, width, and thickness of the bus bars. As a result, the inductance Lp of the positive electrode wiring 11 is made equal (substantially equal) to the equivalent series inductance Lc1 of the first capacitor section C1. The inductance Ln of the negative electrode wiring 12 is made equal (substantially equal) to the equivalent series inductance Lc2 of the second capacitor section C2.

[0022] As shown in Fig. 3, a gap G is formed between the first capacitor portion C1 and the second capacitor portion C2. The gap G is formed between the outer peripheral surface of the elongated cylindrical capacitor C11 and the outer peripheral surface of the elongated cylindrical capacitor C12, and extends in the axial direction (longitudinal direction) of the capacitors C11 and C12. The capacitor Cs (snubber circuit) is disposed in the gap G.

[0023] The smoothing circuit 10 includes a positive terminal 16 connected to the positive wiring 11 and a negative terminal 26 connected to the negative wiring 12. The positive terminal 16 and the negative terminal 26 are arranged side by side and extend in a direction (a predetermined first direction) perpendicular to the axial direction (longitudinal direction) of the capacitors C11, C12 and the longitudinal direction of the smoothing circuit 10 (the direction in which the capacitors C11, C12 are arranged).

[0024] The smoothing circuit 10 includes a positive terminal 18 including a connection 17 with the positive terminal 16 of the positive wiring 11 and the positive terminal 16, and a negative terminal 28 including a connection 27 with the negative terminal 26 of the negative wiring 12 and the negative terminal 26. The capacitor Cs is connected between the positive terminal 18 and the negative terminal 28. More specifically, the capacitor Cs is connected between the connection 17 and the connection 27.

[0025] As shown in Fig. 4, the positive electrode wiring 11, the negative electrode wiring 12, the first capacitor unit C1, the second capacitor unit C2, and the capacitor Cs are housed in a case 30. The case 30 is formed, for example, from an insulating material in the shape of a rectangular cylinder with a bottom (hollow box), and has a lid (not shown). After the positive electrode wiring 11, the negative electrode wiring 12, the first capacitor unit C1, the second capacitor unit C2, and the capacitor Cs are housed inside the case 30, the case 30 is filled with, for example, epoxy resin (insulating resin), and the lid of the case 30 is closed. In this way, the smoothing circuit 10 is configured as a smoothing circuit module (capacitor module).

[0026] The present embodiment described above in detail has the following advantages.

[0027] A positive wiring 11 having a first positive connection P1 connected to the first capacitor section C1 and a second positive connection P2 connected to the second capacitor section C2 intersects with a negative wiring 12 having a first negative connection N1 connected to the second capacitor section C2 and a second negative connection N2 connected to the first capacitor section C1. The inductance Lp of the positive wiring 11 is substantially equal to the equivalent series inductance Lc1 of the first capacitor section C1, and the inductance Ln of the negative wiring 12 is substantially equal to the equivalent series inductance Lc2 of the second capacitor section C2. Therefore, the equivalent series inductances Lc1 and Lc2 (hereinafter referred to as "ESL") of the first capacitor section C1 and the second capacitor section C2 can be offset by the inductances Lp and Ln of the positive wiring 11 and the negative wiring 12, respectively, thereby improving the noise reduction performance of the smoothing circuit 10.

[0028] The smoothing circuit 10 includes the capacitor Cs of the C snubber circuit connected between the positive electrode wiring 11 and the negative electrode wiring 12, and is therefore capable of suppressing an increase in surge voltage applied between the positive electrode wiring 11 and the negative electrode wiring 12. Therefore, a smoothing circuit 10 in which the first capacitor unit C1 and the second capacitor unit C2 are cross-connected to form a three-dimensional intersection between the positive electrode wiring 11 and the negative electrode wiring 12 can be used as a smoothing circuit 10 connected between a DC power supply and a power conversion circuit.

[0029] The first capacitor unit C1 and the second capacitor unit C2 are arranged side by side in a direction perpendicular to a predetermined direction, which makes it easy to arrange the first capacitor unit C1 and the second capacitor unit C2 together in one location. Furthermore, the capacitor Cs is arranged in the gap G between the first capacitor unit C1 and the second capacitor unit C2, which makes it easy to miniaturize the smoothing circuit 10, including the capacitor Cs.

[0030] Because the positive electrode terminal 16 and the negative electrode terminal 26 are arranged side by side, the distance between the positive electrode terminal 16 and the negative electrode terminal 26 can be shortened. Furthermore, the capacitor Cs is connected between the positive electrode terminal 18 and the negative electrode terminal 28. This shortens the wiring length from the connection portion 17 of the positive electrode wiring 11 with the positive electrode terminal 18 to the positive electrode terminal 16, and the wiring length from the connection portion 27 of the negative electrode wiring 12 with the negative electrode terminal 28 to the negative electrode terminal 26. This reduces the inductance of the wiring from the positive electrode terminal 16 to the capacitor Cs and the inductance of the wiring from the negative electrode terminal 26 to the capacitor Cs. As a result, the surge voltage applied between the positive electrode terminal 16 and the negative electrode terminal 26 can be reduced.

[0031] The capacitance Cs of the capacitor Cs of the C snubber circuit, the inductance Lp of the positive wiring 11, the current I flowing through the positive wiring 11, and the allowable value Vb of the surge voltage satisfy Cs>Lp(I / Vb)^2. With this configuration, the electrostatic energy (1 / 2 Cs Vb^2) that can be stored in the capacitor Cs can be made larger than the electromagnetic energy (1 / 2 Lp I^2) stored in the inductance Lp of the positive wiring 11. Therefore, the surge voltage applied between the positive wiring 11 and the negative wiring 12 can be made lower than the allowable value Vb.

[0032] The smoothing circuit 10 includes a case 30 that houses the positive electrode wiring 11, the negative electrode wiring 12, the first capacitor unit C1, the second capacitor unit C2, and the capacitor Cs. With this configuration, the positive electrode wiring 11, the negative electrode wiring 12, the first capacitor unit C1, the second capacitor unit C2, and the capacitor Cs are housed inside the case 30, and the smoothing circuit 10 can be modularized. This makes the smoothing circuit 10 easier to handle.

[0033] The first capacitor unit C1 and the second capacitor unit C2 are arranged so that the positive and negative electrodes are oriented in opposite directions in a predetermined direction. The positive wiring 11 connects the positive electrode C13 of the first capacitor unit C1 to the positive electrode C23 of the second capacitor unit C2 at an angle relative to the predetermined direction. The negative wiring 12 connects the negative electrode C14 of the first capacitor unit C1 to the negative electrode C24 of the second capacitor unit C2 at an angle relative to the predetermined direction. This arrangement allows the positive wiring 11 and the negative wiring 12 to cross over each other using shorter wiring lengths.

[0034] The positive electrode wiring 11 and the negative electrode wiring 12 cross each other at an intersection with the first capacitor portion C1 and the second capacitor portion C2 in between. This configuration makes it easier to arrange the positive electrode wiring 11 and the negative electrode wiring 12 when they cross each other at an intersection.

[0035] The above embodiment can be modified as follows: The same parts as those in the above embodiment are denoted by the same reference numerals and the description thereof will be incorporated herein.

[0036] A capacitor Cs that does not satisfy Cs>Lp(I / Vb)^2 may be employed. Even in this case, the increase in surge voltage applied between the positive wiring 11 and the negative wiring 12 can be suppressed compared to a configuration that does not include a capacitor Cs (C snubber circuit).

[0037] 5, the negative electrode wiring 12 may be extended in the opposite direction to the negative electrode terminal 26 (upward in FIG. 5), and a capacitor Cs may be connected between the end of the positive electrode wiring 11 opposite the positive electrode terminal 16 and the end of the negative electrode wiring 12 opposite the negative electrode terminal 26. Then, the capacitor Cs (snubber circuit) may be disposed in the gap G2 between the first capacitor portion C1 and the second capacitor portion C2 on the side opposite to the positive electrode terminal 16 and the negative electrode terminal 26.

[0038] (Second embodiment) The second embodiment will be described below, focusing on the differences from the first embodiment. Note that the same parts as those in the first embodiment are denoted by the same reference numerals and the description thereof will be incorporated herein.

[0039] 6, in this embodiment, the smoothing circuit 10 includes an RC snubber circuit (snubber circuit) configured with a resistor Rs and a capacitor Cs. The resistor Rs and the capacitor Cs are connected in series between a portion of the positive wiring 11 between the second positive electrode connecting portion P2 and the positive electrode side input terminal Pin, and a portion of the negative wiring 12 between the second negative electrode connecting portion N2 and the negative electrode side input terminal Nin.

[0040] 7 and 8, the capacitor Cs is disposed in the gap G. The resistor Rs and the capacitor Cs are connected between the positive electrode terminal 18 and the negative electrode terminal 28. The resistor Rs is formed in a plate shape. The largest surface Rsa of the resistor Rs is in close contact with the positive electrode wiring 11 (bus bar).

[0041] According to the above configuration, the largest surface Rsa of the resistor Rs is in close contact with the positive electrode wiring 11 formed by the bus bar. This allows the bus bar to function as a heat sink that dissipates heat from the resistor Rs, thereby preventing the resistor Rs from overheating. This embodiment also provides the same advantageous effects as the first embodiment.

[0042] FIG. 9 is a graph showing the simulation results of surge peak voltages in the comparative example and this embodiment.

[0043] In Comparative Example 1, the first capacitor section C1 (two capacitors C11) and the second capacitor section C2 (two capacitors C12) are simply connected in parallel between the positive electrode wiring 11 and the negative electrode wiring 12, and no snubber circuit is provided. In this case, the peak of the surge voltage is 615 [V].

[0044] In Comparative Example 2, the first capacitor section C1 and the second capacitor section C2 are connected in a cross-connected manner and no snubber circuit is provided. In this case, the surge voltage peaks at 734 V. The surge voltage increases because the inductance of the positive electrode wiring 11 and the negative electrode wiring 12 is increased to offset the ESL of the first capacitor section C1 and the second capacitor section C2. In particular, because the first capacitor section C1 and the second capacitor section C2 are connected in a cross-connected manner to form a three-dimensional intersection between the positive electrode wiring 11 and the negative electrode wiring 12, the inductance is doubled, and the surge voltage is higher than in Comparative Example 1.

[0045] In this embodiment, the first capacitor section C1 and the second capacitor section C2 are connected in a cross-connected manner, and an RC snubber circuit is provided, which is composed of a resistor Rs and a capacitor Cs. In this case, the peak of the surge voltage is 608 V. That is, the RC snubber circuit can suppress the rise in the surge voltage applied between the positive electrode wiring 11 and the negative electrode wiring 12.

[0046] It is also possible to employ a configuration in which the surface Rsa with the largest resistance Rs is not in close contact with the positive electrode wiring 11 formed by a bus bar. It is also possible to employ a configuration in which the resistance Rs is not in close contact with the positive electrode wiring 11 formed by a bus bar.

[0047] (Third embodiment) The third embodiment will be described below, focusing on the differences from the first embodiment. Note that the same parts as those in the first embodiment are denoted by the same reference numerals and the description thereof will be incorporated herein.

[0048] As shown in FIG. 10 , in this embodiment, the smoothing circuit 10 includes an RCD snubber circuit (snubber circuit) composed of a resistor Rs, a capacitor Cs, and a diode Ds. The resistor Rs and the diode Ds are connected in parallel to the capacitor Cs. The RCD snubber circuit is connected between a portion of the positive wiring 11 between the second positive electrode connection point P2 and the positive electrode input terminal Pin, and a portion of the negative wiring 12 between the second negative electrode connection point N2 and the negative electrode input terminal Nin. With this configuration, the RCD snubber circuit can suppress an increase in surge voltage applied between the positive wiring 11 and the negative wiring 12. This embodiment also provides the same effects as the first and second embodiments.

[0049] The first to third embodiments can be modified as follows: The same parts as those in the first to third embodiments are denoted by the same reference numerals and the description thereof will be incorporated herein.

[0050] It is also possible to employ a configuration in which the capacitor Cs is disposed in a location other than the gaps G, G2 between the first capacitor portion C1 and the second capacitor portion C2.

[0051] The bus bars forming the positive electrode wiring 11 and the negative electrode wiring 12 may be made of, for example, copper (metal) rods. Even in this case, the same effects as those of the first to third embodiments and their modifications can be achieved.

[0052] The smoothing circuit 10 may be configured without the case 30, that is, may not be modularized.

[0053] The positive electrode wiring 11 and the negative electrode wiring 12 may cross each other in a multilevel crossing without sandwiching the first capacitor portion C1 and the second capacitor portion C2 therebetween.

[0054] The first capacitor section C1 may be composed of one capacitor C11 or three or more capacitors C11. The second capacitor section C2 may be composed of one capacitor C21 or three or more capacitors C21.

[0055] The smoothing circuit 10 according to the first to third embodiments and their modifications can also be applied to a smoothing circuit connected between a DC charger and a battery.

[0056] The above-described embodiment and modifications may be combined within the scope of possible combinations.

[0057] Characteristic configurations extracted from the above-described embodiments and modifications will be described below. [Configuration 1] A smoothing circuit (10) including a positive electrode wiring (11), a negative electrode wiring (12), and a first capacitor unit (C1) and a second capacitor unit (C2) connected in parallel between the positive electrode wiring and the negative electrode wiring, the positive electrode wiring has a first positive electrode connecting portion (P1) connected to the first capacitor portion and a second positive electrode connecting portion (P2) connected to the second capacitor portion, the negative electrode wiring has a first negative electrode connecting portion (N1) connected to the second capacitor portion and a second negative electrode connecting portion (N2) connected to the first capacitor portion, The positive electrode wiring and the negative electrode wiring cross each other at an intersection, the inductance of the positive wiring is substantially equal to the equivalent series inductance of the first capacitor section, the inductance of the negative wiring is substantially equal to the equivalent series inductance of the second capacitor section, A smoothing circuit including a snubber circuit (Cs, Rs, Rd) connected between the positive wiring and the negative wiring. [Configuration 2] The first capacitor section and the second capacitor section are arranged side by side, 2. The smoothing circuit according to configuration 1, wherein the snubber circuit is disposed in a gap (G, G2) between the first capacitor section and the second capacitor section. [Configuration 3] A positive terminal (16) connected to the positive wiring; a negative electrode terminal (26) connected to the negative electrode wiring and arranged next to the positive electrode terminal, 3. The smoothing circuit according to claim 1, wherein the snubber circuit is connected between a connection portion (17) of the positive wiring with the positive terminal and a positive terminal portion (18) including the positive terminal, and a connection portion (27) of the negative wiring with the negative terminal and a negative terminal portion (28) including the negative terminal. [Configuration 4] The snubber circuit includes a capacitor (Cs) and a plate-shaped resistor (Rs), the positive electrode wiring and the negative electrode wiring are formed by bus bars which are conductive plates or rods, 4. The smoothing circuit according to any one of configurations 1 to 3, wherein the surface with the greatest resistance (Rsa) is in close contact with the positive electrode wiring or the negative electrode wiring. [Configuration 5] The snubber circuit includes a capacitor (Cs), 5. The smoothing circuit according to any one of configurations 1 to 4, wherein the capacitance Cs of the capacitor, the inductance Lp of the positive electrode wiring, the current I flowing through the positive electrode wiring, and the allowable value Vb of the surge voltage satisfy Cs>Lp(I / Vb)^2. [Configuration 6] The smoothing circuit according to any one of configurations 1 to 5, comprising a case (30) that houses the positive wiring, the negative wiring, the first capacitor unit, the second capacitor unit, and the snubber circuit. [Configuration 7] The first capacitor section has a first electrode (C13) and a second electrode (C14), The second capacitor section has a first electrode (C23) and a second electrode (C24), the first capacitor unit and the second capacitor unit are arranged so that the orientations of the first electrodes and the second electrodes are opposite to each other in a predetermined direction, and are arranged side by side in a direction perpendicular to the predetermined direction, the positive electrode wiring connects the first electrode of the first capacitor unit and the first electrode of the second capacitor unit obliquely with respect to the predetermined direction, 7. The smoothing circuit according to any one of configurations 1 to 6, wherein the negative electrode wiring connects the second electrode of the first capacitor unit and the second electrode of the second capacitor unit obliquely with respect to the predetermined direction. [Configuration 8] 8. The smoothing circuit according to claim 7, wherein the positive electrode wiring and the negative electrode wiring cross each other at an intersection with the first capacitor unit and the second capacitor unit interposed therebetween. [Explanation of symbols]

[0058] 10...smoothing circuit, 11...positive electrode wiring, 12...negative electrode wiring, C1...first capacitor section, C2...second capacitor section, Cs...capacitor, Ds...diode, N1...first negative electrode connection section, N2...second negative electrode connection section, P1...first positive electrode connection section, P2...second positive electrode connection section, Rs...resistor.

Claims

1. A smoothing circuit (10) including a positive electrode wiring (11), a negative electrode wiring (12), and a first capacitor unit (C1) and a second capacitor unit (C2) connected in parallel between the positive electrode wiring and the negative electrode wiring, The positive wiring has a first positive electrode connection part (P1) connected to the first capacitor part and a second positive electrode connection part (P2) connected to the second capacitor part, The negative electrode wiring has a first negative electrode connection part (N1) connected to the second capacitor part and a second negative electrode connection part (N2) connected to the first capacitor part, The positive electrode wiring and the negative electrode wiring cross each other at an intersection, the inductance of the positive wiring is substantially equal to the equivalent series inductance of the first capacitor section, the inductance of the negative wiring is substantially equal to the equivalent series inductance of the second capacitor section, A smoothing circuit comprising a snubber circuit (Cs, Rs, Rd) connected between the positive wiring and the negative wiring.

2. The first capacitor section and the second capacitor section are arranged side by side, 2. The smoothing circuit according to claim 1, wherein the snubber circuit is disposed in a gap (G, G2) between the first capacitor section and the second capacitor section.

3. A positive terminal (16) connected to the positive wiring; a negative electrode terminal (26) connected to the negative electrode wiring and arranged next to the positive electrode terminal; 3. The smoothing circuit according to claim 1, wherein the snubber circuit is connected between a connection portion (17) of the positive wiring with the positive terminal and a positive terminal portion (18) including the positive terminal, and a connection portion (27) of the negative wiring with the negative terminal and a negative terminal portion (28) including the negative terminal.

4. The snubber circuit includes a capacitor (Cs) and a plate-shaped resistor (Rs), the positive electrode wiring and the negative electrode wiring are formed by bus bars which are conductive plates or rods, The smoothing circuit according to claim 1 or 2, wherein the surface (Rsa) having the greatest resistance is in close contact with the positive electrode wiring or the negative electrode wiring.

5. The snubber circuit includes a capacitor (Cs), 3. The smoothing circuit according to claim 1, wherein the capacitance Cs of the capacitor, the inductance Lp of the positive electrode wiring, the current I flowing through the positive electrode wiring, and the allowable value Vb of the surge voltage satisfy Cs > Lp (I / Vb)^2.

6. The smoothing circuit according to claim 1 or 2, further comprising a case (30) that houses the positive wiring, the negative wiring, the first capacitor unit, the second capacitor unit, and the snubber circuit therein.

7. The first capacitor portion has a first electrode (C13) and a second electrode (C14), The second capacitor section has a first electrode (C23) and a second electrode (C24), the first capacitor unit and the second capacitor unit are arranged so that the orientations of the first electrodes and the second electrodes are opposite to each other in a predetermined direction, and are arranged side by side in a direction perpendicular to the predetermined direction, the positive wiring connects the first electrode of the first capacitor unit and the first electrode of the second capacitor unit obliquely with respect to the predetermined direction, The smoothing circuit according to claim 1 or 2, wherein the negative electrode wiring connects the second electrode of the first capacitor unit and the second electrode of the second capacitor unit obliquely with respect to the predetermined direction.

8. The smoothing circuit according to claim 7 , wherein the positive electrode wiring and the negative electrode wiring cross each other at an intersection with the first capacitor unit and the second capacitor unit therebetween.

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