Capacitor substrate unit and power conversion device

Abstract

The capacitor substrate unit of the present invention includes: a wiring substrate (30); a positive busbar (20a) having a positive power supply terminal (22a), a positive load terminal (23a), and a positive smoothing terminal (24a); a negative busbar (20b) having a negative power supply terminal (22b), a negative load terminal (23b), and a negative smoothing terminal (24b); and a plurality of capacitors (10) having a positive capacitor terminal (10a) and a negative capacitor terminal (10b). The wiring includes a positive wiring (30a) that connects the positive smoothing terminal (24a) and the positive capacitor terminal (10a) in series and in parallel, and a negative wiring (30b) that connects the negative smoothing terminal (24b) and the negative capacitor terminal (10b) in series and in parallel. DC power is supplied from the positive power supply terminal (22a) to the positive load terminal (23a). The sum of the resistance value and the DC resistance value from the negative power supply terminal (22b) to the negative load terminal (23b) is less than the sum of the DC resistance value between the positive power supply terminal (22a) and the positive load terminal (23a) through multiple positive smoothing terminals (24a) and positive wiring (30a) and the DC resistance value between the negative power supply terminal (22b) and the negative load terminal (23b) through multiple negative smoothing terminals (24b) and negative wiring (30b). Furthermore, the inductance value between the positive load terminal (23a) and the negative load terminal (23b) through the positive smoothing terminal (24a), wiring, capacitor (10), and negative smoothing terminal (24b) is less than the sum of the inductance values ​​from the positive power supply terminal (22a) to the positive load terminal (23a) and from the negative power supply terminal (22b) to the negative load terminal (23b).

Description

Technical Field

[0001] This application relates to capacitor substrate units and power conversion devices. Background Technology

[0002] In the field of power electronics, power conversion devices such as AC / DC converters, DC / DC converters, and inverters are used. Power conversion devices include power conversion units that convert power using the switching action of semiconductor elements, i.e., switching elements. Additionally, power conversion devices include capacitors for smoothing voltages where an AC component overlaps the DC component. As a structure for the capacitors included in power conversion devices, a substrate unit is used, for example, to arrange multiple capacitor elements on a substrate. To meet the high output requirements of power conversion devices and increase the output current of the switching elements, techniques are needed to increase the allowable current of the capacitor substrate unit.

[0003] As a capacitor substrate unit that receives a large current from the outside, a structure in which a capacitor is directly connected to a conductive plate made of metal has been disclosed (for example, see Patent Document 1). Existing technical documents Patent documents

[0004] Patent Document 1: Japanese Patent Application Publication No. 2001-352767 Summary of the Invention The technical problem that the invention aims to solve

[0005] In the capacitor substrate unit of Patent Document 1, since the alternating current generated by the pulsation of the input voltage overlaps with the direct current, both the direct current component and the alternating current component flow simultaneously through the metal conductive plate. When the current is increased in the disclosed capacitor substrate unit, the heat generated by the conductive plate and other components connected to the conductive plate increases. Because the metal conductive plate has excellent thermal conductivity, the heat generated is directly transferred to the capacitor, causing the capacitor temperature to rise. If the capacitor temperature rises, problems such as capacitor degradation and malfunction may occur. Furthermore, when a direct current overlapping with the alternating current flows through the circuit board on which the capacitor is mounted, the heat generated by the circuit board increases. To suppress the heat generated by the circuit board, the conductive wiring pattern of the circuit board is sometimes thickened, or heat dissipation or cooling structures are provided for the circuit board and the capacitor, but this makes the capacitor substrate unit more complex and costly.

[0006] On the other hand, on the DC power supply side of a power conversion device equipped with a capacitor bank unit, an external device powered by the DC voltage of the DC power supply is sometimes connected. In this case, for the external device, it is necessary to suppress the voltage ripple caused by the AC component overlapping the DC voltage due to the operation of the power conversion device to below a specified value. Ideally, the AC current component that causes voltage ripple should not flow to the external device, but should be smoothed within the capacitor bank unit. In the disclosed capacitor bank unit, since the DC current component and the AC current component overlap flowing through the metal conductive plate, if the impedance of the conductive plate cannot be minimized, the AC current component flowing to the outside increases. When the AC current component flowing to the outside increases, there is a problem of increased DC voltage ripple. In external devices powered by DC voltage, voltage ripple becomes a cause of malfunctions and accidental operation.

[0007] Therefore, the purpose of this application is to obtain a capacitor substrate unit that suppresses the temperature rise of the capacitor and suppresses the AC current component flowing out to the outside, and a power conversion device that suppresses the AC current component flowing out to the outside. Technical means for solving technical problems

[0008] The capacitor substrate unit disclosed in this application includes: a wiring substrate with wiring; a positive busbar having at least one positive power terminal connected to the positive terminal of a power source, a plurality of positive load terminals respectively connected to the positive terminals of a plurality of loads, and a plurality of positive smoothing terminals connected to the wiring; a negative busbar having at least one negative power terminal connected to the negative terminal of the power source, a plurality of negative load terminals respectively connected to the negative terminals of the plurality of loads, and a plurality of negative smoothing terminals connected to the wiring; and a plurality of capacitors having positive capacitor terminals and negative capacitor terminals, the positive capacitor terminals and the negative capacitor terminals being connected to the wiring. The wiring includes positive wiring that connects multiple positive smoothing terminals and multiple positive capacitor terminals in series and in parallel, and negative wiring that connects multiple negative smoothing terminals and multiple negative capacitor terminals in series and in parallel. The DC resistance value on the busbar side is less than the DC resistance value on the wiring substrate side. The busbar side DC resistance value is the sum of the DC resistance value of the positive busbar from the positive power terminal to the positive load terminal and the DC resistance value of the negative busbar from the negative power terminal to the negative load terminal. The wiring substrate side DC resistance value is the sum of the DC resistance values ​​between the positive power terminal and the positive load terminal via multiple positive smoothing terminals and the positive wiring (i.e., the positive wiring substrate side DC resistance value) and the DC resistance values ​​between the negative power terminal and the negative load terminal via multiple negative smoothing terminals and the negative wiring (i.e., the negative wiring substrate side DC resistance value). The capacitor-side inductance is less than the busbar-side inductance. The capacitor-side inductance is the inductance between the positive load terminal and the negative load terminal via a plurality of positive smoothing terminals, the positive wiring, a plurality of capacitors, the negative wiring, and a plurality of negative smoothing terminals. The busbar-side inductance is the sum of the inductance of the positive busbar from the positive power terminal to the positive load terminal and the inductance of the negative busbar from the negative power terminal to the negative load terminal.

[0009] The power conversion device disclosed in this application includes the capacitor substrate unit disclosed in this application and a power conversion unit connected between each of the plurality of positive load terminals and each of the plurality of negative load terminals. Invention Effects

[0010] According to the capacitor substrate unit disclosed in this application, the sum of the DC resistance value of the positive busbar from the positive power supply terminal to the positive load terminal and the DC resistance value of the negative busbar from the negative power supply terminal to the negative load terminal, i.e., the DC resistance value on the busbar side, is less than the DC resistance value between the positive power supply terminal and the positive load terminal via multiple positive smoothing terminals and positive wiring, i.e., the DC resistance value on the positive wiring substrate side, and the sum of the DC resistance values ​​between the negative power supply terminal and the negative load terminal via multiple negative smoothing terminals and negative wiring, i.e., the DC resistance value on the negative wiring substrate side. Furthermore, the DC resistance between the positive load terminal and the negative load terminal via multiple positive smoothing terminals, positive wiring, and multiple... The inductance of the capacitor, negative wiring, and multiple negative smoothing terminals (i.e., the capacitor-side inductance) is less than the sum of the inductance of the positive busbar from the positive power terminal to the positive load terminal and the inductance of the negative busbar from the negative power terminal to the negative load terminal (i.e., the busbar-side inductance). Therefore, almost no DC current flows through the positive wiring, capacitor, and negative wiring, thereby suppressing the temperature rise of the capacitor. Since the AC current caused by the pulsation of the output voltage of the load connected to the positive and negative load terminals flows along the path from the positive smoothing terminal through the positive wiring, capacitor, and negative wiring to the negative smoothing terminal, the AC current component flowing out from the capacitor substrate unit to the outside can be suppressed.

[0011] According to the power conversion device disclosed in this application, since it includes the capacitor substrate unit disclosed in this application and the power conversion unit respectively connected between each of the plurality of positive load terminals and each of the plurality of negative load terminals, the alternating current caused by the pulsation of the output voltage of the power conversion unit flows along the path from the positive smoothing terminal through the positive wiring, the capacitor and the negative wiring to the negative smoothing terminal, thereby suppressing the alternating current component flowing out of the power conversion device to the outside. Attached Figure Description

[0012] Figure 1 This is a top view showing the capacitor substrate unit according to Embodiment 1. Figure 2 This is a side view of the capacitor substrate unit according to Embodiment 1. Figure 3 This is a diagram showing the main parts of the capacitor substrate unit according to Embodiment 1. Figure 4 This is a cross-sectional view of the wiring substrate of the capacitor substrate unit according to Embodiment 1. Figure 5 This is a schematic diagram showing an outline of the power conversion device involved in Embodiment 1. Figure 6This is a schematic circuit diagram of the capacitor substrate unit according to Embodiment 1. Figure 7 This is an equivalent circuit diagram of the capacitor substrate unit involved in Embodiment 1. Figure 8 This is a diagram showing the path of the DC current in the equivalent circuit diagram of the capacitor substrate unit according to Embodiment 1. Figure 9 This is a diagram showing the path of alternating current in the equivalent circuit diagram of the capacitor substrate unit according to Embodiment 1. Detailed Implementation

[0013] Hereinafter, the capacitor substrate unit and power conversion device according to the embodiments of this application will be described based on the accompanying drawings. In each drawing, the same or equivalent components and parts are labeled with the same reference numerals.

[0014] Implementation method 1. Figure 1 This is a top view showing the capacitor substrate unit 1 according to Embodiment 1. Figure 2 This is a side view showing capacitor substrate unit 1. Figure 3 This diagram shows the main parts of the capacitor substrate unit 1, and is a schematic diagram showing the connection between the wiring substrate 30, the capacitor 10, and the busbar 20. Figure 4 This is a cross-sectional view of the wiring substrate 30 of capacitor substrate unit 1. Figure 5 This is a schematic diagram showing the outline of the power conversion device 500 according to Embodiment 1. Figure 6 This is a schematic diagram of the capacitor substrate unit. Figure 7 This is the equivalent circuit diagram of capacitor substrate unit 1. Figure 8 This is a diagram showing the path of the DC current in the equivalent circuit diagram of capacitor substrate unit 1. Figure 9 This is a diagram showing the path of alternating current in the equivalent circuit diagram of capacitor substrate unit 1. The capacitor substrate unit 1 is mounted on a power conversion device 500 that converts desired power into DC or AC voltage. The capacitor substrate unit 1 has a plurality of capacitors 10 to smooth the voltage that has an AC component superimposed on the DC component.

[0015] <Power Conversion Device 500> like Figure 5As shown, the power conversion device 500 includes a capacitor substrate unit 1 and a power conversion unit 200 as a load. The capacitor substrate unit 1 has a load terminal 23 connected to it. The load terminal 23 has a plurality of positive load terminals 23a connected to the positive terminal of the power conversion unit 200, and a plurality of negative load terminals 23b connected to the negative terminal of the power conversion unit 200. The power conversion unit 200 is connected between each of the plurality of positive load terminals 23a and each of the plurality of negative load terminals 23b. The power conversion unit 200 has, for example, the function of converting DC power to AC power. The capacitor substrate unit 1 has a power terminal 22 connected to an external power supply 100. The power terminal 22 has a positive power terminal 22a connected to the positive terminal of the external power supply 100, and a negative power terminal 22b connected to the negative terminal of the external power supply 100. The power conversion device 500 converts the power from the external power supply 100 into DC or AC voltage and outputs it to an external device 300. In this embodiment, the capacitor substrate unit 1 is shown to have a structure with one positive power terminal 22a and one negative power terminal 22b, but it is not limited to this and may also have a structure including multiple positive power terminals 22a and negative power terminals 22b. In addition, the number of power conversion units 200 connected to the capacitor substrate unit 1 is not limited to 3.

[0016] <Capacitor substrate unit 1> like Figure 1 As shown, the capacitor substrate unit 1 includes a capacitor 10, a busbar 20, and a wiring substrate 30 with wiring. In the capacitor substrate unit 1 of this embodiment, the capacitor 10 and the busbar 20 are mounted on the wiring substrate 30, as shown... Figure 6 As shown, the capacitor 10 and the busbar 20 are electrically connected via wiring formed on the wiring substrate 30.

[0017] The capacitor 10 is an electrical component that has the function of charging, primarily storing power, and discharging the stored power. Typically, aluminum electrolytic capacitors, film capacitors, or ceramic capacitors are used for the capacitor 10 in the capacitor substrate unit 1. In this embodiment, the case where an aluminum electrolytic capacitor is used for the capacitor 10 will be described. Aluminum electrolytic capacitors have the highest capacitance per unit volume. Therefore, by using multiple aluminum electrolytic capacitors connected in parallel, a small-sized capacitor substrate unit 1 with a large capacity can be achieved. Figure 1 This shows a layout example with 28 capacitors 10 connected in parallel, but the number of capacitors 10 is not limited to this.

[0018] Capacitor 10 has a positive capacitor terminal 10a and a negative capacitor terminal 10b. For example... Figure 2As shown, a capacitor 10 is mounted on the surface of the wiring substrate 30. Positive capacitor terminal 10a and negative capacitor terminal 10b... Figure 2 (Not shown in the diagram) Wiring connection with the wiring substrate 30. Multiple capacitors 10 are connected in parallel between multiple positive smoothing terminals 24a and multiple negative smoothing terminals 24b. This configuration enables a small-sized, high-capacity capacitor substrate unit 1. In this embodiment, 28 capacitors 10 are connected in parallel to three positive smoothing terminals 24a and three negative smoothing terminals 24b, but the number is not limited to this.

[0019] Busbar 20 is the primary current path through which direct current flows. For example... Figure 1 As shown, the busbar 20 includes a positive busbar 20a and a negative busbar 20b. The positive busbar 20a has at least one positive power terminal 22a connected to the positive terminal of the external power supply 100, multiple positive load terminals 23a respectively connected to the positive terminals of multiple power conversion units 200, and multiple positive smoothing terminals 24a connected to wiring. Figure 1 (Not shown in the figure). The negative busbar 20b has at least one negative power terminal 22b connected to the negative terminal of the external power supply 100, multiple negative load terminals 23b respectively connected to the negative terminals of multiple power conversion units 200, and multiple negative smoothing terminals 24b connected to wiring. Figure 1 (Not shown in the diagram). Power terminal 22 is formed by positive power terminal 22a and negative power terminal 22b, and load terminal 23 is formed by positive load terminal 23a and negative load terminal 23b. Busbar 20 is electrically and mechanically connected to wiring substrate 30 via positive smoothing terminal 24a and negative smoothing terminal 24b. Since busbar 20 and wiring substrate 30 can be electrically and mechanically connected via reflow soldering, processing steps and costs can be reduced, the structure is simplified, and the productivity of capacitor substrate unit 1 can be improved.

[0020] Busbar 20 uses copper, a material with low resistivity and excellent conductivity. The material of busbar 20 is not limited to copper; other metals are also acceptable. Because copper is easily machined, such as cut, slicing, bending, and drilling, complex shapes can be easily manufactured. Furthermore, copper can be processed using die-stamping. Stamping can process copper in a shorter time compared to machining, thus reducing the manufacturing cost of busbar 20. Additionally, Figure 1 The capacitor substrate unit 1 shown includes three load terminals 23, but it can be one or more than four.

[0021] An insulating member (not shown) is disposed between the positive busbar 20a and the negative busbar 20b. The insulating member prevents short circuits between the positive and negative busbars 20a and 20b. The insulating member is, for example, insulating paper. The positive busbar 20a, negative busbar 20b, and insulating member are integrally formed by the resin portion 21. Methods for integrally forming the resin portion 21 and the busbar 20 include insert molding and external molding. The resin portion 21 has screw holes for fastening the busbar 20 to the wiring substrate 30. Using these holes and screws, the busbar 20 and the wiring substrate 30 are mechanically connected. Here, the resin portion 21 is fixed to the wiring substrate 30 at three points. By fixing the resin portion 21 to the wiring substrate 30 in this way, the shock resistance of the busbar 20 can be improved. Furthermore, the reliability of the electrical connection between the busbar 20 and the wiring substrate 30 can be improved.

[0022] The wiring substrate 30 is, for example, a glass composite substrate such as CEM-3 or a glass epoxy board such as FR-4, a general printed wiring substrate. A wiring layer 50 with wiring is stacked on the wiring substrate 30, and the wiring substrate 30 has a multilayer structure with at least two wiring layers 50 stacked, including a surface wiring layer and a back wiring layer. The wiring substrate 30 includes screw holes 40 for fastening to a housing or the like with screws. The wiring of the wiring substrate 30 includes a positive wiring 30a connecting a positive smoothing terminal 24a and a positive capacitor terminal 10a, and a negative wiring 30b connecting a negative smoothing terminal 24b and a negative capacitor terminal 10b. Figure 6 As shown, the positive wiring layer forming the positive wiring 30a is configured to connect the positive smoothing terminal 24a and the positive capacitor terminal 10a in parallel, and the negative wiring layer forming the negative wiring 30b is configured to connect the negative smoothing terminal 24b and the negative capacitor terminal 10b in parallel. Figure 6 The load terminal 23 is omitted. Figure 6 An example of five capacitors 10 connected in parallel is shown, but the number of capacitors 10 is not limited to this.

[0023] The wiring substrate 30 includes: a first positive-side wiring 31a with n (n being an integer of 2 or more) positive smoothing terminals 24a connected in a distributed manner; a second positive-side wiring 31b with the positive capacitor terminals 10a of a plurality of capacitors 10 connected in a distributed manner; n positive-side connecting wirings 31c that connect the n portions of the first positive-side wiring 31a connected to the n positive smoothing terminals 24a and the n distributed portions of the second positive-side wiring 31b respectively; a first negative-side wiring 32a with n negative smoothing terminals 24b connected in a distributed manner; a second negative-side wiring 32b with the negative capacitor terminals 10b of the plurality of capacitors 10 connected in a distributed manner; and n negative-side connecting wirings 32c that connect the n portions of the first negative-side wiring 32a connected to the n negative smoothing terminals 24b and the n distributed portions of the second negative-side wiring 32b respectively. By including wiring with capacitors 10 connected in parallel, low inductance of the wiring substrate 30 can be achieved.

[0024] The first positive electrode side wiring 31a and the second positive electrode side wiring 31b are formed in a straight line and are arranged in parallel with each other. The first negative electrode side wiring 32a and the second negative electrode side wiring 32b are formed in a straight line and are arranged in parallel with each other. By configuring the wiring in a matrix shape, the low inductance of the wiring substrate 30 can be further achieved.

[0025] The wiring substrate 30 is not limited to a laminated structure, but by forming a laminated structure, the positive and negative patterns of the wiring layers can be set in close proximity, thus making it easy to reduce the inductance of the wiring substrate 30. By using a glass composite substrate or a glass epoxy substrate, production steps can be reduced by reflow soldering, and the capacitor substrate unit 1 corresponding to high current can be manufactured with more readily available general materials, thus improving the productivity of the capacitor substrate unit 1.

[0026] like Figure 3 As shown, capacitor 10 and busbar 20 are electrically connected via solder 60 to either positive wiring 30a or negative wiring 30b on wiring layer 50 disposed on the surface of wiring substrate 30. Figure 3 The positive busbar 20a is shown, but the negative busbar 20b is also shown. Reflow soldering can be used as a method for electrical connection via solder 60. Reflow soldering allows for electrical connection between the component and the wiring layer 50 on the surface of the wiring substrate 30 without requiring the electrodes of the component mounted on the wiring substrate 30 to penetrate to the back side of the wiring substrate 30. However, it is necessary to select components and parts appropriate for reflow soldering. Besides reflow soldering, wave soldering is another method for mounting components and parts onto the wiring substrate 30. In the case of wave soldering, the components, parts, and the wiring substrate 30 mounted on the wiring substrate 30 need to be selected as appropriate for wave soldering. Reflow soldering, wave soldering, or both can be selected as a method for mounting components and parts onto the wiring substrate 30, depending on the requirements.

[0027] like Figure 4 As shown, the wiring substrate 30 in this embodiment is, for example, a multilayer glass epoxy board with four wiring layers 50. The wiring substrate 30 is stacked sequentially from top to bottom as follows: pads (not shown), solder resist 70, surface wiring layer 50a, prepreg 80, second wiring layer 50b, core material 90, third wiring layer 50c, prepreg 80, back wiring layer 50d, and solder resist 70. The surface wiring layer 50a, second wiring layer 50b, third wiring layer 50c, and back wiring layer 50d are generally made of copper foil with a thickness of 35 μm or 70 μm, but are not specifically limited to this. Considering the heat generated (temperature rise) assumed based on the current flowing through the wiring layer, the thickness of the wiring layer 50 can be arbitrarily set along with the width of the wiring pattern.

[0028] <Equivalent circuit of capacitor substrate unit 1> use Figure 7 Explain the equivalent circuit of capacitor substrate unit 1. Figure 7 The diagram does not show all 28 capacitors; some are omitted, and only 3 capacitors are shown. The portion enclosed by dashed lines, i.e., the positive busbar 20a, has a positive power terminal 22a, a positive load terminal 23a, and a positive smoothing terminal 24a. Similarly, the portion enclosed by dashed lines, i.e., the negative busbar 20b, has a negative power terminal 22b, a negative load terminal 23b, and a negative smoothing terminal 24b. The portion enclosed by dotted lines, i.e., the capacitor 10, has a positive capacitor terminal 10a and a negative capacitor terminal 10b. The portion enclosed by double-dotted lines, i.e., the positive wiring 30a, connects multiple positive smoothing terminals 24a and multiple positive capacitor terminals 10a in series and parallel. Similarly, the portion enclosed by double-dotted lines, i.e., the negative wiring 30b, connects multiple negative smoothing terminals 24b and multiple negative capacitor terminals 10b in series and parallel.

[0029] The positive busbar 20a, negative busbar 20b, positive wiring 30a, negative wiring 30b, and capacitor 10 all have DC resistance and inductance components. For example... Figure 7 As shown, both the positive busbar 20a and the negative busbar 20b have a DC resistance component 20R and an inductance component 20L. Both the positive wiring 30a and the negative wiring 30b have a DC resistance component 30R and an inductance component 30L. The capacitor 10 has a DC resistance component 10R and an inductance component 10L. The capacitance component of the capacitor 10 is set to 10C. Figure 7 In the text, the DC resistance components 10R, 20R, and 30R, and the inductance components 10L, 20L, and 30L recorded at multiple locations actually have different values ​​depending on their respective locations.

[0030] The DC resistance component 20R of the positive busbar 20a and the negative busbar 20b is calculated as the resistivity ρ (Ω·m) of the conductor × the length l (m) of the conductor / the cross-sectional area A (m²) of the conductor. 2 The term "conductor" here refers to the raw materials that constitute the positive busbar 20a and the negative busbar 20b. For example, if the conductor is copper, its resistivity is approximately 1.68 × 10⁻⁶. -8 (Ω·m). The inductance component 20L of the positive busbar 20a and the negative busbar 20b is determined by the raw materials, shape, magnitude and direction of the current flowing through the positive busbar 20a and the negative busbar 20b, and is divided into self-inductance component and mutual inductance component.

[0031] The DC resistance component 30R of the positive electrode wiring 30a and the negative electrode wiring 30b is determined by the resistivity of the raw material of the wiring formed on the wiring substrate 30, the length of the wiring, the cross-sectional area of ​​the wiring, and the pattern of the wiring. In addition to the raw material of the wiring formed on the wiring substrate 30, the length of the wiring, the cross-sectional area of ​​the wiring, and the pattern of the wiring, the inductance component 30L of the positive electrode wiring 30a and the negative electrode wiring 30b is also determined by the magnitude and direction of the current flowing through the wiring.

[0032] The DC resistance component 10R and inductance component 10L of capacitor 10 are called equivalent series resistance (ESR) and equivalent series inductance (ESL), respectively, and are known components as equivalent circuits of a single capacitor.

[0033] <Path of DC current in the equivalent circuit of capacitor substrate unit 1> use Figure 8 illustrate Figure 7 The path of the DC current in the equivalent circuit of capacitor substrate unit 1 shown. Figure 7 An external power supply 100, serving as a DC power supply, is connected between the positive power terminal 22a and the negative power terminal 22b. A power conversion unit 200 is connected between a set of positive load terminals 23a and the negative load terminals 23b. Figure 8 In the middle, the power conversion unit 200 is connected to the load terminal 23, which is furthest from the power supply terminal 22. Figure 8 In the image, the thick arrows indicate the main paths through which the direct current flows.

[0034] The sum of the DC resistance of the positive busbar 20a from the positive power terminal 22a to the positive load terminal 23a and the DC resistance of the negative busbar 20b from the negative power terminal 22b to the negative load terminal 23b, i.e., the DC resistance on the busbar side, is less than the DC resistance between the positive power terminal 22a and the positive load terminal 23a via multiple positive smoothing terminals 24a and positive wiring 30a, i.e., the DC resistance on the positive wiring substrate side, and the sum of the DC resistance between the negative power terminal 22b and the negative load terminal 23b via multiple negative smoothing terminals 24b and negative wiring 30b, i.e., the DC resistance on the negative wiring substrate side, i.e., the DC resistance on the wiring substrate side. In the capacitor substrate unit 1 of this embodiment, the sum of the DC resistance component 20R of the path from the positive power supply terminal 22a of the positive busbar 20a to the positive load terminal 23a and the DC resistance component 20R of the path from the negative power supply terminal 22b of the negative busbar 20b to the negative load terminal 23b is set to be as small as possible less than the sum of the DC resistance components 30R of the positive wiring 30a and the negative wiring 30b. By setting it in this way, the DC resistance value on the busbar side is smaller than the DC resistance value on the wiring substrate side.

[0035] Subsequently, the sum of the DC resistance component 20R of the path from the positive power terminal 22a of the positive busbar 20a to the positive load terminal 23a, and the sum of the DC resistance component 20R of the path from the negative power terminal 22b of the negative busbar 20b to the negative load terminal 23b, is recorded as Σ20R. Furthermore, the sum of the DC resistance components 30R of the positive wiring 30a and the negative wiring 30b is recorded as Σ30R. That is, in the capacitor substrate unit 1, Σ20R << Σ30R. In other words, the sum of the DC resistance value from the positive power terminal 22a of the positive busbar 20a to the positive load terminal 23a and the DC resistance value from the negative power terminal 22b of the negative busbar 20b to the negative load terminal 23b is set to be as small as possible less than the sum of the DC resistance values ​​of the positive wiring 30a and the negative wiring 30b. Among the multiple load terminals 23, the load terminal 23 furthest from the power supply terminal 22 has the largest Σ20R between it and the power supply terminal 22. This maximum Σ20R is set to Σ20R << Σ30R.

[0036] Therefore, when setting the DC resistance component, such as Figure 8 As shown by the thick arrow, the DC current supplied by the external power supply 100 flows along the path from the positive busbar 20a through the power conversion unit 200 to the negative busbar 20b. The DC current has difficulty flowing through the path via multiple positive smoothing terminals 24a and positive wiring 30a to the positive load terminal 23a. Figure 8(The arrows shown are dashed lines). Similarly, direct current is difficult to flow through the path from multiple negative smoothing terminals 24b and negative wiring 30b to the negative power terminal 22b. Figure 8 (The dashed arrows are shown). In this case, although heat generated by the large DC current occurs at the positive busbar 20a and negative busbar 20b or at the components connected to the busbar 20, almost no DC current flows through the positive wiring 30a, capacitor 10, and negative wiring 30b, so almost no heat is generated at these locations. Even if heat is generated at the busbar 20 and the components connected to the busbar 20, the capacitor 10 is connected to the busbar 20 through the wiring on the wiring board 30, so the heat generated by the busbar 20, etc., has little thermal impact on the capacitor 10. Therefore, it is possible to prevent the temperature of the capacitor 10 from rising. Since it is possible to prevent the temperature of the capacitor 10 from rising, it is possible to suppress the deterioration and failure of the capacitor 10.

[0037] The aluminum electrolytic capacitor used in this embodiment experiences a decrease in capacitance and an accelerated increase in series equivalent resistance (ESR) due to temperature rise over time. However, since the temperature of capacitor 10 can be prevented from rising when using an aluminum electrolytic capacitor, the degradation of the aluminum electrolytic capacitor can be suppressed.

[0038] Specifically, it is preferable that Σ20R is less than 1 / 30 of Σ30R. If Σ20R is less than 1 / 30 of Σ30R, approximately 97% of the DC current flows to busbar 20. Since only about 3% of the DC current flows through the positive wiring 30a, capacitor 10, and negative wiring 30b, heat generation in these components can be suppressed. Furthermore, since the temperature rise of capacitor 10 can be prevented, degradation and malfunctions of capacitor 10 can be suppressed.

[0039] The following is a specific example. When the wiring length is equal to the busbar length, the thickness of the copper foil wiring layer is 0.105 mm, the wiring width is 4 mm, and the cross-sectional area of ​​the copper busbar 20 is 13 mm². 2 Therefore, the DC resistance value on the busbar side can be less than 1 / 30th of the DC resistance value on the wiring substrate side. Examples of the dimensions and structure of the wiring and busbar 20 are not limited to this.

[0040] <Path of alternating current in the equivalent circuit of capacitor substrate unit 1> use Figure 9 illustrate Figure 7 The path of alternating current in the equivalent circuit of capacitor substrate unit 1 shown. Figure 7An external power supply 100, serving as a DC power supply, is connected between the positive power supply terminal 22a and the negative power supply terminal 22b, and a power conversion unit 200 is connected between a set of positive load terminals 23a and negative load terminals 23b. Figure 9 In the image, the thick arrows indicate the main paths through which the alternating current flows.

[0041] In capacitor substrate unit 1, due to the pulsation of the voltage input to capacitor substrate unit 1, a periodic pulsating current is generated in the current during the charging and discharging of capacitor 10. If this periodic pulsating current is considered as alternating current, the voltage output to power conversion unit 200 may sometimes fluctuate. In this embodiment, capacitor substrate unit 1 suppresses the fluctuation of output voltage caused by the pulsation of input voltage.

[0042] For each of the plurality of positive load terminals 23a and negative load terminals 23b, the inductance value between the positive load terminals 23a and negative load terminals 23b via the plurality of positive smoothing terminals 24a, positive wiring 30a, plurality of capacitors 10, negative wiring 30b and the plurality of negative smoothing terminals 24b, i.e., the capacitor-side inductance value, is less than the sum of the inductance value of the positive busbar 20a from the positive power supply terminal 22a to the positive load terminal 23a and the inductance value of the negative busbar 20b from the negative power supply terminal 22b to the negative load terminal 23b, i.e., the busbar-side inductance value. In the capacitor substrate unit 1 of this embodiment, the sum of the inductance component 20L of the path from the positive power supply terminal 22a of the positive busbar 20a to the positive load terminal 23a and the inductance component 20L of the path from the negative power supply terminal 22b of the negative busbar 20b to the negative load terminal 23b is set to be as large as possible than the sum of the inductance component 30L of the positive wiring 30a and the negative wiring 30b connected between the positive smoothing terminal 24a and the negative smoothing terminal 24b and the inductance component 10L of the capacitor 10.

[0043] Subsequently, the sum of the inductance component 20L of the path from the positive power terminal 22a of the positive busbar 20a to the positive load terminal 23a, and the sum of the inductance component 20L of the path from the negative power terminal 22b of the negative busbar 20b to the negative load terminal 23b is recorded as Σ20L. Furthermore, the sum of the inductance component 30L of the positive wiring 30a and negative wiring 30b connected between the positive smoothing terminal 24a and the negative smoothing terminal 24b, and the sum of the inductance component 10L of the capacitor 10 is recorded as Σ(30L+10L). That is, in the capacitor substrate unit 1, Σ20L >> Σ(30L+10L) is set. In other words, the sum of the inductance values ​​from the positive power terminal 22a of the positive busbar 20a to the positive load terminal 23a and from the negative power terminal 22b of the negative busbar 20b to the negative load terminal 23b is set to be as large as possible the sum of the inductance values ​​of the positive wiring 30a from the positive smoothing terminal 24a to the negative smoothing terminal 24b, the negative wiring 30b, and the capacitor 10.

[0044] If the inductance component is set in this way, then as Figure 9 The thick arrows indicate that the alternating current caused by the pulsation of the output voltage from the power conversion unit 200 flows along the path from the positive smoothing terminal 24a through the positive wiring 30a, capacitor 10, and negative wiring 30b to the negative smoothing terminal 24b. The alternating current is less likely to flow along the path from the positive busbar 20a through the external power supply 100 to the negative busbar 20b. Figure 9 The current flows through the dashed arrow shown. Therefore, since the alternating current caused by the pulsation of the input voltage hardly flows to the external power supply 100, the fluctuation of the power supply voltage caused by the pulsation of the output voltage can be suppressed. Therefore, it is possible to obtain a capacitor substrate unit 1 that suppresses the alternating current component flowing to the outside.

[0045] Specifically, Σ20L is preferably more than 20 times Σ(30L+10L). If Σ20L is more than 20 times Σ(30L+10L), approximately 95% of the alternating current flows to the positive wiring 30a, capacitor 10, and negative wiring 30b. Since only about 5% of the alternating current flows through the busbar 20 to the external power supply 100, fluctuations in the power supply voltage caused by output voltage pulsations can be suppressed.

[0046] When the sum of the inductance values ​​of the positive wiring 30a and the negative wiring 30b on the capacitor side is less than one-third of the inductance value on the busbar side, the alternating current caused by the pulsation of the output voltage from the power conversion unit 200 still flows along the path from the positive smoothing terminal 24a through the positive wiring 30a, the capacitor 10, and the negative wiring 30b to the negative smoothing terminal 24b. Therefore, the alternating current component flowing out from the capacitor substrate unit 1 can be significantly suppressed. By setting the dimensions and structure of the wiring and the busbar 20 as described above, the sum of the inductance values ​​of the positive wiring 30a and the negative wiring 30b on the capacitor side can be less than one-third of the inductance value on the busbar side.

[0047] In this embodiment, the positive busbar 20a has n positive load terminals 23a respectively connected to the positive terminals of n (n is an integer of 2 or more) power conversion units 200, and n positive smoothing terminals 24a respectively arranged adjacent to the n positive load terminals 23a. Similarly, the negative busbar 20b has n negative load terminals 23b respectively connected to the negative terminals of the n power conversion units 200, and n negative smoothing terminals 24b respectively arranged adjacent to the n negative load terminals 23b. Figure 7 As shown, by configuring the positive smoothing terminal 24a and the negative smoothing terminal 24b in this way, the alternating current caused by the pulsation of the output voltage from the power conversion unit 200 can easily flow along the path from the positive smoothing terminal 24a through the positive wiring 30a, the capacitor 10, and the negative wiring 30b to the negative smoothing terminal 24b. Since the alternating current can easily flow along the path from the positive smoothing terminal 24a through the positive wiring 30a, the capacitor 10, and the negative wiring 30b to the negative smoothing terminal 24b, the fluctuation of the power supply voltage caused by the pulsation of the output voltage can be significantly suppressed.

[0048] By using the capacitor substrate unit 1 set to Σ20R << Σ30R and Σ20L >> Σ(30L+10L) in the power conversion device 500, even when a large current flows through the power conversion device 500, most of the DC current component flows to the busbar 20 and not to the wiring substrate 30 and capacitor 10. Therefore, the temperature rise of capacitor 10 is suppressed, and degradation and failure of capacitor 10 can be suppressed. In addition, since most of the AC current component caused by voltage pulsation of the power conversion unit 200 flows to the wiring substrate 30 and capacitor 10 and not to the external power supply 100, fluctuations in power supply voltage caused by pulsation can be suppressed. Therefore, a power conversion device 500 that suppresses the AC current component flowing to the outside can be obtained. Furthermore, since the AC current component flowing to the outside is suppressed, devices connected to the external power supply 100 can operate stably.

[0049] The load connected to the capacitor substrate unit 1 is not limited to the power conversion unit 200. The capacitor substrate unit 1 can also be used in devices different from the power conversion device 500.

[0050] As described above, in the capacitor substrate unit 1 according to Embodiment 1, the sum of the DC resistance value of the positive busbar 20a from the positive power supply terminal 22a to the positive load terminal 23a and the DC resistance value of the negative busbar 20b from the negative power supply terminal 22b to the negative load terminal 23b, i.e., the busbar-side DC resistance value, is less than the DC resistance value between the positive power supply terminal 22a and the positive load terminal 23a via multiple positive smoothing terminals 24a and positive wiring 30a, i.e., the positive wiring substrate-side DC resistance value, and the sum of the DC resistance values ​​between the negative power supply terminal 22b and the negative load terminal 23b via multiple negative smoothing terminals 24b and negative wiring 30b, i.e., the wiring substrate-side DC resistance value. Furthermore, the DC resistance between the positive load terminal 23a and the negative load terminal 23b via multiple positive smoothing terminals 24a... a. The inductance value of the positive wiring 30a, the plurality of capacitors 10, the negative wiring 30b, and the plurality of negative smoothing terminals 24b, i.e., the capacitor-side inductance value, is less than the sum of the inductance value of the positive busbar 20a from the positive power terminal 22a to the positive load terminal 23a and the inductance value of the negative busbar 20b from the negative power terminal 22b to the negative load terminal 23b, i.e., the busbar-side inductance value. Since almost no DC current flows through the positive wiring 30a, the capacitors 10, and the negative wiring 30b, the temperature rise of the capacitors 10 can be suppressed. The AC current caused by the pulsation of the output voltage from the power conversion unit 200 flows along the path from the positive smoothing terminal 24a through the positive wiring 30a, the capacitors 10, and the negative wiring 30b to the negative smoothing terminal 24b, thereby suppressing the AC current component flowing out from the capacitor substrate unit 1 to the outside.

[0051] When the positive busbar 20a has n positive load terminals 23a that are respectively connected to the positive terminals of n (n is an integer of 2 or more) power conversion units 200 and n positive smoothing terminals 24a that are respectively arranged adjacent to the n positive load terminals 23a, and the negative busbar 20b has n negative load terminals 23b that are respectively connected to the negative terminals of n power conversion units 200 and n negative smoothing terminals 24b that are respectively arranged adjacent to the n negative load terminals 23b, it is easy to make the alternating current caused by the pulsation of the output voltage from the power conversion unit 200 flow along the path from the positive smoothing terminal 24a through the positive wiring 30a, the capacitor 10 and the negative wiring 30b to the negative smoothing terminal 24b.

[0052] The wiring substrate 30 includes: a first positive side wiring 31a with n positive smoothing terminals 24a distributedly connected; a second positive side wiring 31b with the positive capacitor terminals 10a of a plurality of capacitors 10 distributedly connected; n positive side connection wirings 31c that respectively connect n portions of the first positive side wiring 31a connected to the n positive smoothing terminals 24a and n distributed portions of the second positive side wiring 31b; a first negative side wiring 32a with n negative smoothing terminals 24b distributedly connected; a second negative side wiring 32b with the negative capacitor terminals 10b of the plurality of capacitors 10 distributedly connected; and n negative side connection wirings 32c that respectively connect n portions of the first negative side wiring 32a connected to the n negative smoothing terminals 24b and n distributed portions of the second negative side wiring 32b. In this case, low inductance of the wiring substrate 30 can be achieved.

[0053] When the first positive electrode side wiring 31a and the second positive electrode side wiring 31b are formed in a straight line and connected in parallel with each other, and the first negative electrode side wiring 32a and the second negative electrode side wiring 32b are formed in a straight line and connected in parallel with each other, the low inductance of the wiring substrate 30 can be further realized.

[0054] When multiple capacitors 10 are connected in parallel between multiple positive smoothing terminals 24a and multiple negative smoothing terminals 24b, a small and high-capacity capacitor substrate unit 1 can be realized. Furthermore, when the wiring substrate 30 is provided with a wiring layer 50 having wiring, the positive and negative patterns of the wiring layer are arranged close together, making it easy to reduce the inductance of the wiring substrate 30. By reducing the inductance of the wiring substrate 30, the alternating current caused by the pulsation of the output voltage from the power conversion unit 200 can easily flow along the path from the positive smoothing terminal 24a through the positive wiring 30a, the capacitor 10, and the negative wiring 30b to the negative smoothing terminal 24b.

[0055] When the DC resistance on the busbar side is less than 1 / 30th of the DC resistance on the wiring board side, almost no DC current flows through the positive wiring 30a, capacitor 10, and negative wiring 30b, thus significantly suppressing heat generation in these components. When the sum of the inductance values ​​of the positive wiring 30a and negative wiring 30b on the capacitor side is less than 1 / 3 of the inductance value on the busbar side, the AC current caused by the pulsation of the output voltage from the power conversion unit 200 still flows along the path from the positive smoothing terminal 24a through the positive wiring 30a, capacitor 10, and negative wiring 30b to the negative smoothing terminal 24b, thus significantly suppressing the AC current component flowing outward from the capacitor board unit 1.

[0056] When capacitor 10 is an aluminum electrolytic capacitor, since aluminum electrolytic capacitors have the largest capacitance per unit volume, a small and high-capacity capacitor substrate unit 1 can be achieved by using multiple aluminum electrolytic capacitors in parallel. Furthermore, when the positive busbar 20a and negative busbar 20b are electrically and mechanically connected to the wiring substrate 30, the busbar 20 and wiring substrate 30 can be electrically and mechanically connected by reflow soldering, thus reducing processing steps and costs, simplifying the structure, and improving the productivity of the capacitor substrate unit 1. Additionally, when the wiring substrate 30 is a multilayer glass composite substrate or glass epoxy board, reflow soldering can reduce production steps, allowing the capacitor substrate unit 1, which supports high current, to be manufactured using readily available general materials, thus improving the productivity of the capacitor substrate unit 1.

[0057] The power conversion device 500 according to Embodiment 1 includes the capacitor substrate unit 1 disclosed in this application and a power conversion unit 200 respectively connected between each of the plurality of positive load terminals 23a and each of the plurality of negative load terminals 23b. The alternating current caused by the pulsation of the output voltage from the power conversion unit 200 flows along the path from the positive smoothing terminal 24a through the positive wiring 30a, the capacitor 10 and the negative wiring 30b to the negative smoothing terminal 24b, so the alternating current component flowing out of the power conversion device 500 can be suppressed.

[0058] Furthermore, although this application describes various exemplary implementation methods and embodiments, the various features, methods and functions described in one or more implementation methods are not limited to specific implementation methods, but can also be applied to implementation methods individually, or in various combinations to be applied to implementation methods. Therefore, it can be assumed that numerous variations not illustrated are also included within the scope of the technology disclosed in this application. For example, this includes cases where at least one constituent element is modified, added to, or omitted, and cases where at least one constituent element is extracted and combined with constituent elements of other embodiments. Label Explanation

[0059] 1. Capacitor substrate unit; 10. Capacitor; 10a. Positive capacitor terminal; 10b. Negative capacitor terminal; 10L, 20L, 30L inductor components; 10R, 20R, 30R DC resistance components; 20. Busbar; 20a. Positive busbar; 20b. Negative busbar; 21. Resin section; 22. Power terminal; 22a. Positive power terminal; 22b. Negative power terminal; 23. Load terminal; 23a. Positive load terminal; 23b. Negative load terminal; 24a. Positive smoothing terminal; 24b. Negative... Extremely smooth terminal, 30 wiring board, 30a positive wiring, 30b negative wiring, 31a first positive side wiring, 31b second positive side wiring, 31c positive side connection wiring, 32a first negative side wiring, 32b second negative side wiring, 32c negative side connection wiring, 40 screw fastening hole, 50 wiring layer, 60 solder, 70 solder resist, 80 prepreg, 90 core material, 100 external power supply, 200 power conversion unit, 300 external device, 500 power conversion device.

Claims

1. A capacitor substrate unit, characterized in that, include: Wiring substrate with wiring; A positive busbar having at least one positive power terminal connected to the positive terminal of a power source, a plurality of positive load terminals respectively connected to the positive terminals of a plurality of loads, and a plurality of positive smoothing terminals connected to the wiring. A negative busbar, comprising at least one negative power terminal connected to the negative terminal of the power source, a plurality of negative load terminals respectively connected to the negative terminals of a plurality of loads, and a plurality of negative smoothing terminals connected to the wiring; and Multiple capacitors, each having a positive capacitor terminal and a negative capacitor terminal, are connected to the wiring. The wiring includes positive wiring that connects multiple positive smoothing terminals and multiple positive capacitor terminals in series and in parallel, and negative wiring that connects multiple negative smoothing terminals and multiple negative capacitor terminals in series and in parallel. The DC resistance value on the busbar side is less than the DC resistance value on the wiring substrate side. The busbar side DC resistance value is the sum of the DC resistance value of the positive busbar from the positive power terminal to the positive load terminal and the DC resistance value of the negative busbar from the negative power terminal to the negative load terminal. The wiring substrate side DC resistance value is the sum of the DC resistance values ​​between the positive power terminal and the positive load terminal via multiple positive smoothing terminals and the positive wiring (i.e., the positive wiring substrate side DC resistance value) and the DC resistance values ​​between the negative power terminal and the negative load terminal via multiple negative smoothing terminals and the negative wiring (i.e., the negative wiring substrate side DC resistance value). The capacitor-side inductance is less than the busbar-side inductance. The capacitor-side inductance is the inductance between the positive load terminal and the negative load terminal via a plurality of positive smoothing terminals, the positive wiring, a plurality of capacitors, the negative wiring, and a plurality of negative smoothing terminals. The busbar-side inductance is the sum of the inductance of the positive busbar from the positive power terminal to the positive load terminal and the inductance of the negative busbar from the negative power terminal to the negative load terminal.

2. The capacitor substrate unit as claimed in claim 1, characterized in that, The positive busbar has n positive load terminals that are respectively connected to the positive terminals of the n loads, and n positive smoothing terminals that are respectively arranged adjacent to the n positive load terminals, wherein n is an integer of 2 or more. The negative busbar has n negative load terminals that are respectively connected to the negative terminals of the n loads, and n negative smoothing terminals that are respectively arranged adjacent to the n negative load terminals.

3. The capacitor substrate unit as described in claim 2, characterized in that, The wiring substrate includes: a first positive-side wiring that disperses and connects n positive smoothing terminals; a second positive-side wiring that disperses and connects the positive capacitor terminals of a plurality of capacitors; n positive-side connecting wirings that connect n portions of the first positive-side wiring connected to the n positive smoothing terminals and n dispersed portions of the second positive-side wiring; a first negative-side wiring that disperses and connects n negative smoothing terminals; a second negative-side wiring that disperses and connects the negative capacitor terminals of the plurality of capacitors; and n negative-side connecting wirings that connect n portions of the first negative-side wiring connected to the n negative smoothing terminals and n dispersed portions of the second negative-side wiring.

4. The capacitor substrate unit as described in claim 3, characterized in that, The first positive electrode side wiring and the second positive electrode side wiring are formed in a straight line and are arranged in parallel with each other. The first negative electrode side wiring and the second negative electrode side wiring are formed in a straight line and are connected in parallel.

5. The capacitor substrate unit as described in any one of claims 1 to 4, characterized in that, A plurality of capacitors are connected in parallel between the plurality of positive smoothing terminals and the plurality of negative smoothing terminals.

6. The capacitor substrate unit as described in any one of claims 1 to 4, characterized in that, The wiring substrate is provided with a wiring layer having the wiring.

7. The capacitor substrate unit as described in any one of claims 1 to 4, characterized in that, The DC resistance value on the busbar side is less than 1 / 30th of the DC resistance value on the wiring board side.

8. The capacitor substrate unit as claimed in any one of claims 1 to 4, characterized in that, The sum of the inductance values ​​of the positive and negative wirings in the capacitor-side inductance value is less than one-third of the busbar-side inductance value.

9. The capacitor substrate unit as claimed in any one of claims 1 to 4, characterized in that, The capacitor is an aluminum electrolytic capacitor.

10. The capacitor substrate unit as claimed in any one of claims 1 to 4, characterized in that, The positive and negative busbars are electrically and mechanically connected to the wiring substrate.

11. The capacitor substrate unit as claimed in any one of claims 1 to 4, characterized in that, The wiring substrate is a multi-layered glass composite substrate or a glass epoxy board.

12. A power conversion device, characterized in that, include: The capacitor substrate unit as described in any one of claims 1 to 11; as well as A power conversion unit connected between each of the plurality of positive load terminals and each of the plurality of negative load terminals.

Images