Power Conversion Device

Abstract

To provide a power conversion device that allows miniaturization.SOLUTION: A power conversion device includes a power conversion circuit, a smoothing circuit portion having first and second output capacitors 154, 155, a positive electrode side conductor 170 and a negative electrode side conductor having a bent structure, and a substrate 500 having a positive electrode side output terminal, a negative electrode side output terminal, and first and second substrate connection portions. One end of the positive electrode side conductor is connected to the positive electrode side output of the power conversion circuit, and the other end is connected to the positive electrode side output terminal. One end of the negative electrode side conductor is connected to the negative electrode side output of the power conversion circuit, and the other end is connected to the negative electrode side output terminal. The output capacitors are mounted on the substrate 500, one end of each output capacitor is connected to the positive electrode side conductor at a first substrate connection portion 50, and the other end is connected to the negative electrode side conductor at a second substrate connection portion 60. The shortest distance between the first and second substrate connection portions is shorter than the terminal-to-terminal length of the first capacitor and longer than the terminal-to-terminal length of the second capacitor. The second capacitor is mounted between the first and second substrate connection portions.SELECTED DRAWING: Figure 4A

Description

[Technical Field]

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

[0002] To ensure passenger space in moving bodies such as electric vehicles or aircraft, miniaturization of power conversion devices mounted on the moving bodies is required. Moving bodies such as electric vehicles are equipped with multiple power conversion devices. For example, such moving bodies are equipped with a step-down converter, which receives input from a high-voltage battery of several hundred volts and converts and supplies power to a 14-volt load or auxiliary battery. The step-down converter has multiple semiconductor switching elements for power conversion, and switching of these switching elements superimposes ripple or switching noise on the output of the step-down converter. If ripple or switching noise is superimposed on the output of the step-down converter, it may cause malfunction of auxiliary electrical components or peripheral devices to which power is supplied.

[0003] To reduce this ripple and switching noise, a step-down converter is generally connected to a smoothing circuit section consisting of a smoothing reactor and a smoothing capacitor, and an output filter section combining a ferrite core and a capacitor. The smoothing circuit section can suppress ripple. The output filter section can suppress both ripple and switching noise.

[0004] A filter module for a power converter having such functions is disclosed in Patent Document 1. The filter module for a power converter in Patent Document 1 includes a smoothing circuit section and a filter circuit section. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2018 / 193589 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the circuit configuration of the filter module for a power converter described in Patent Document 1 includes a smoothing circuit section and a filter circuit section, which causes a problem of increasing the size of the power converter.

[0007] The present disclosure has been made to solve such problems, and aims to provide a power conversion device that can be made smaller than conventional technology. [Means for solving the problem]

[0008] One aspect of a power conversion device according to an embodiment of the present disclosure is a power conversion device including: a power conversion circuit including a plurality of semiconductor elements; a smoothing circuit section including a plurality of output capacitors, a positive electrode side conductor having at least one bent structure, and a negative electrode side conductor; a positive electrode side output terminal; a negative electrode side output terminal; and a substrate having a first substrate connection portion and at least one second substrate connection portion, wherein one end of the positive electrode side conductor is connected to a positive electrode side output of the power conversion circuit, the other end of the positive electrode side conductor is connected to the positive electrode side output terminal, one end of the negative electrode side conductor is connected to a negative electrode side output of the power conversion circuit, and the other end of the negative electrode side conductor is connected to the negative electrode side output terminal. a plurality of output capacitors mounted on the substrate, one end of each output capacitor connected to the positive electrode conductor at the first substrate connection portion and the other end of each output capacitor connected to the negative electrode conductor at at least one second substrate connection portion, the plurality of output capacitors including one or more first capacitors and one or more second capacitors smaller in size than the first capacitors, the shortest distance on the substrate between the first substrate connection portion and the second substrate connection portion is shorter than the length between the terminals of the first capacitor and longer than the length between the terminals of the second capacitor, and the second capacitor is mounted between the first substrate connection portion and the second substrate connection portion. [Effects of the Invention]

[0009] According to the power conversion device according to the embodiment of the present disclosure, it is possible to provide a power conversion device that can be made smaller than conventional power conversion devices. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 10 is a circuit configuration diagram of a power conversion device of a comparative example. [Figure 2A] FIG. 10 is a diagram showing the layout of components on the upper surface of the substrate of the smoothing circuit section of the comparative example. [Figure 2B] FIG. 10 is a component layout diagram of a cross section of a smoothing circuit section of a comparative example. [Figure 3] 1 is a circuit configuration diagram according to a first embodiment. [Figure 4A] 3 is an example of a component layout diagram on the upper surface of a substrate of a smoothing circuit section according to the first embodiment. [Figure 4B] 3 is an example of a component layout diagram in a cross section of a smoothing circuit section according to the first embodiment. [Figure 5] 4 shows the frequency characteristics of impedance of the capacitor according to the first embodiment. [Figure 6] 3 is an example of a component layout diagram on the upper surface of a substrate of a smoothing circuit section according to the first embodiment. [Figure 7] 3 is an example of a component layout diagram on the upper surface of a substrate of a smoothing circuit section according to the first embodiment. [Figure 8] 1 is a perspective view of a lug terminal according to a first embodiment. [Figure 9] FIG. 10 is a circuit configuration diagram according to a second embodiment. [Figure 10] FIG. 10 is a circuit configuration diagram according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Various embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. Note that components with the same or similar reference numerals in the drawings have the same or similar configurations or functions, and redundant descriptions of such components will be omitted.

[0012] Embodiment 1 <Comparative Example> First, in order to better explain the features of the power conversion device of the present disclosure, a circuit diagram of a power conversion device as a comparative example will be explained with reference to FIG.

[0013] Fig. 1 is a circuit configuration diagram of a power conversion device 1C of a comparative example. As shown in Fig. 1, the power conversion device 1C has an input filter circuit section 110, a power conversion circuit 10, a smoothing circuit section 150C, and an output filter section 160. The power conversion circuit 10 has a switching circuit section 120, a transformer section 130, and a rectifier circuit section 140.

[0014] (Input filter circuit section) The input filter circuit section 110 has capacitors 111 , 112 , and 113 , and removes ripple components and switching noise components that propagate to the DC power supply 100 .

[0015] (Switching circuit section) The switching circuit unit 120 has switching elements 121 to 124 connected in a bridge configuration. The switching circuit unit 120 converts a DC voltage applied from the DC power supply 100 into an AC voltage. The switching elements 121 to 124 are not limited to self-extinguishing semiconductor switching elements such as Si (Silicon)-MOSFETs (Metal Oxide Semiconductor Field Effect Transistors), but may also be semiconductor switching elements using wide band gap semiconductors such as SiC (Silicon Carbide) or GaN (Gallium Nitride), or diamond-based semiconductors.

[0016] (transformer section) Transformer unit 130 has a primary winding 131 and a secondary winding 132. Transformer unit 130 outputs an AC voltage applied to primary winding 131 to secondary winding 132 while providing insulation.

[0017] (rectifier circuit section) Rectifier circuit section 140 is configured with rectifying elements, that is, diodes 141 and 142. Rectifier circuit section 140 rectifies the AC voltage output from secondary winding 132 of transformer section 130 and converts it into a DC voltage.

[0018] (Smoothing circuit section) The smoothing circuit unit 150C has a smoothing reactor 151 and a smoothing capacitor 152. The smoothing circuit unit 150C smoothes the ripple superimposed on the DC voltage rectified by the rectifier circuit unit 140, and outputs the smoothed DC voltage to the output filter unit 160.

[0019] The smoothing reactor 151 is connected to the positive output of the rectifier circuit unit 140, i.e., the positive output of the power conversion circuit 10, at a connection point 20. The smoothing reactor 151 and a positive output bus bar (positive conductor) 170 that connects the smoothing reactor 151 and the output terminal 200 are connected at a connection point 30. As a result, the positive output bus bar 170 is connected to the positive output of the power conversion circuit 10 via the smoothing reactor 151.

[0020] Smoothing capacitor 152 is mounted on substrate 500 (see FIG. 2B ) and connected between positive output bus bar 170 and GND2. Positive output bus bar 170 is connected to wiring member 153 at positive output connection point 40, and is connected to substrate 500 via wiring member 153 at first substrate screwing portion 50. Note that first substrate screwing portion 50 corresponds to connection point 50 in the comparative example. As a result, positive output bus bar 170 is connected to smoothing capacitor 152 mounted on substrate 500 via positive output connection point 40, wiring member 153, and first substrate screwing portion 50.

[0021] Furthermore, the substrate 500 and GND2 are connected via the negative electrode side conductor 70 from the second substrate screw fastening portion 60 to the connection point 80.

[0022] (Output filter section) The output filter section 160 has a ferrite core 161 and a capacitor 162. The output filter section 160 reduces ripple and switching noise superimposed on the DC voltage smoothed by the smoothing circuit section 150C, and outputs the DC voltage with reduced ripple and switching noise to the output terminal 200. The ferrite core 161 is installed so as to pass through a positive output bus bar 170 that connects the positive output connection point 40 and the output terminal 200. The capacitor 162 is connected between a branch point 163 between the ferrite core 161 and the output terminal 200 and GND2.

[0023] The input filter circuit 110, switching circuit 120, transformer 130, rectifier circuit 140, smoothing circuit 150C, and output filter 160 are fixed to a conductor housing. The housing itself is at the same potential as GND. Therefore, the negative output of the rectifier circuit 140, i.e., the negative output of the power conversion circuit 10, is at the same potential as GND2, and the second board screwing portion 60 is connected to GND2, which is the housing, at a connection point 80 via the negative conductor 70.

[0024] FIG. 2A is a layout diagram of smoothing capacitor 152 of a comparative example. Note that FIG. 2A does not include smoothing reactor 151 in order to illustrate the characteristic features of this embodiment. The smoothing circuit unit 150C and output filter unit 160 must reduce low-frequency ripple (Vrip) of several kHz to several hundred kHz resulting from the drive frequency and high-frequency switching noise of several hundred kHz to several hundred MHz resulting from switching of the switching elements, both of which are superimposed on the output of the power conversion circuit 10. Here, the ripple can be calculated using the following equation (1), where Lf is the reactance of the smoothing reactor [uH], Cf is the capacitance of the smoothing capacitor [uF], Vout is the output voltage [V], fsw is the switching frequency [Hz], V1 is the input voltage [V], and N is the transformer turns ratio (N1 (number of primary turns) / N2 (number of secondary turns)) [−]. TIFF0007784983000001.tif14166

[0025] The input voltage V1 and output voltage Vout are external factors, and the turns ratio N is determined by V1 and Vout. Furthermore, the drive frequency fsw is restricted by the performance of the power converter's switching elements and cannot be changed significantly. Therefore, in order to reduce ripple (Vrip), it is necessary to increase Lf or Cf. Since smoothing reactors are larger and more expensive than smoothing capacitors, in order to reduce ripple in a smaller size and at lower cost, it is necessary to increase the capacitance of the smoothing capacitor to a certain extent.

[0026] FIG. 2B is a cross-sectional view of the smoothing circuit unit 150C of the comparative example, taken along a dotted line parallel to the X-axis in FIG. 2A, as viewed from the direction A. Note that in FIG. 2B, in order to illustrate the characteristic features of the present embodiment, the smoothing reactor 151 is not shown, but rather the positive output bus bar 170, the negative conductor 70, the substrate 500, the smoothing capacitor 152, and other electronic components mounted on the substrate 500, which are not designated by reference numerals. In the comparative example, as shown in FIG. 2B, other electronic components, such as a pulse transformer, necessary for operating the switching circuit unit 120 are mounted on the substrate 500. Therefore, the positive output bus bar 170 and the substrate 500 cannot be directly joined. Therefore, a wiring member 153 is required, extending from the positive output connection point 40 to the connection point 50, to connect the positive output bus bar 170 and the substrate 500. As shown in FIG. 2B, in the configuration of the comparative example, the wiring member 153 is required, the parasitic inductance of the smoothing capacitor 152 increases, and the filter performance in the high-frequency range is poor. Therefore, in the power conversion device of the comparative example, an output filter section 160 shown in FIG. 1 is provided to suppress high-frequency switching noise and the like.

[0027] Next, a circuit diagram according to the first embodiment will be described with reference to FIG. 3. FIG. 3 is a circuit configuration diagram of a power conversion device 1 according to the first embodiment of the present disclosure. The circuit configuration diagram of the power conversion device 1 according to the first embodiment differs from FIG. 1, which is a circuit configuration diagram of a power conversion device 1C of a comparative example, in the following two points. First, the power conversion device 1C of the comparative example includes an output filter section 160, whereas the power conversion device 1 of the first embodiment does not include the output filter section 160. Second, the smoothing circuit section 150C of the comparative example includes one type of smoothing capacitor 152, whereas the smoothing circuit section 150 of the first embodiment includes two types of smoothing capacitors (first capacitor) 154 and smoothing capacitor (second capacitor) 155 connected in parallel as output capacitors. The second board screwing section 60, which corresponds to the negative side of the smoothing capacitors 154 and 155, is connected to GND via the negative-side conductor 70 and is at the same potential as GND. Moreover, since the configuration other than the smoothing capacitors 154 and 155 is the same as that of the power conversion device of the comparative example shown in FIG. 1, the same reference numerals are used in the illustration, and redundant explanations will be omitted.

[0028] Next, a specific example of the configuration according to Embodiment 1 will be described with reference to FIG. 4. In FIG. 4, a substrate 500, a smoothing capacitor, and a positive electrode side output bus bar are shown in order to indicate characteristic portions of the present embodiment. FIG. 4A is an arrangement diagram of the smoothing capacitor according to Embodiment 1. As shown in FIG. 4A, a second capacitor 155, which is a smoothing capacitor, is mounted between a first substrate screw portion 50, which is a screw portion between the positive electrode side output bus bar 170 and the substrate 500, and a second substrate screw portion 60, which is a screw portion between the negative electrode side conductor 70 and the substrate 500. The first substrate screw portion 50 and the second substrate screw portion 60 are located at an end portion of the substrate 500. Here, the end portion means a region at a distance from the end of the substrate 500 where one or several ceramic capacitors can be arranged, and as a specific distance, it is about 20 mm or less. A first capacitor 154, which is a smoothing capacitor, is not mounted between the first substrate screw portion 50 and the second substrate screw portion 60, but is mounted in parallel closest to both the first substrate screw portion 50 and the second substrate screw portion 60. "Closest" means as close as possible so that the parasitic inductance of the wiring from the substrate screw portion to the capacitor terminal can be made as small as possible. At this time, as shown in FIG. 4A, assuming A: the distance between the first substrate screw portion 50 and the second substrate screw portion 60, B: the terminal-to-terminal distance of the second capacitor 155, and C: the terminal-to-terminal distance of the first capacitor 154, the first capacitor 154 and the second capacitor 155 are arranged such that B < A < C. As the first capacitor 154, the same product as the smoothing capacitor 152 of the comparative example may be used. This is because, as described above in accordance with Equation (1), it is necessary to increase Lf or Cf to suppress ripple, so a capacitor with a large capacitance density is used. It can be confirmed that the inductance of the loop from the first substrate screw portion 50 to the first capacitor 154 and then to the second substrate screw portion 60 in FIG. 4A is equivalent to the inductance of the loop from the first substrate screw portion 50 to the smoothing capacitor 152 and then to the second substrate screw portion 60 in FIG. 2A, which is a comparative example. That is, ripple can be reduced in the same manner as in the comparative example.

[0029] On the other hand, a capacitor having a smaller size and capacitance and improved high-frequency characteristics than first capacitor 154 may be used as second capacitor 155. FIG. 5 is a graph showing the impedance-frequency characteristics of first capacitor 154 and second capacitor 155 according to the first embodiment. As shown in FIG. 5, the resonant frequency of second capacitor 155 is higher than the resonant frequency of first capacitor 154. By providing second capacitor 155 with good high-frequency characteristics, high-frequency filter performance is improved, and therefore switching noise caused by switching of the switching elements can be attenuated without providing an output filter, thereby achieving a smaller and less costly power conversion device.

[0030] Furthermore, since the first capacitor 154 in FIG. 4A and the smoothing capacitor 152 in FIG. 2A according to the comparative example are the same product, the distance A from the first board screwing portion 50 to the second board screwing portion 60 in FIG. 4A is significantly shorter than that in FIG. 2A according to the comparative example. In other words, parasitic inductance is significantly reduced, and high-frequency filter characteristics are improved. Due to this significant improvement in high-frequency filter characteristics, the configuration of the first embodiment eliminates the need for an output filter section. Eliminating the output filter section makes it possible to reduce the size and cost of the power converter.

[0031] Furthermore, it is preferable that the first capacitor 154 be mounted so that the total distance from one terminal to the first board screw fastening part 50 and the other terminal to the second board screw fastening part 60 is as short as possible, taking into consideration mounting constraints. This minimizes the terminal parasitic inductance of the smoothing capacitor, improving filter performance in the high frequency range and enabling further reductions in capacitor capacitance, thereby achieving a smaller and less costly power conversion device.

[0032] Furthermore, on the substrate 500, the first capacitor 154 is mounted in the same orientation as the second capacitor 155. This shortens the distance from the first substrate screwing portion 50 to the first capacitor 154 and the distance from the second substrate screwing portion 60 to the second capacitor 155, thereby reducing the terminal parasitic inductance of the smoothing capacitor, improving filter performance in the high frequency range and reducing switching noise. This allows for a smaller and less expensive power conversion device.

[0033] FIG. 4B is a cross-sectional view of the smoothing circuit section according to the first embodiment, viewed from the direction B of the dotted line parallel to the X-axis in FIG. 4A. Note that the smoothing reactor is not shown here, but rather the positive output bus bar 170, the negative conductor 70, the substrate 500, the smoothing capacitors 154 and 155, and other electronic components mounted on the substrate are shown. While film capacitors or electrolytic capacitors are advantageous for ensuring capacitance as smoothing capacitors, the first embodiment uses ceramic capacitors. Compared to film capacitors and electrolytic capacitors, ceramic capacitors offer higher vibration resistance when mounted on a substrate. In recent years, demands for reliability and quality have increased for on-board power converters, leading to a demand for high vibration resistance. Both film capacitors and electrolytic capacitors require additional vibration-prevention components, such as a fixing case and adhesive, which increases costs. Furthermore, the element height of both film capacitors and electrolytic capacitors is higher than that of ceramic capacitors, resulting in a larger power converter. Because ceramic capacitors have a smaller component height, they can be mounted on both sides of a substrate. Considering these points, although ceramic capacitors have a small capacitance per volume, using ceramic capacitors is appropriate for reducing the size and cost of power conversion devices.

[0034] As shown in FIG. 4B, the positive output bus bar 170 has two bending structures 300 and 400. The first substrate screw portion 50 located at an end portion near the edge of the substrate 500 directly connects the substrate 500 and the positive output bus bar 170 by screwing. This configuration makes it possible to eliminate the wiring member 153 shown in FIG. 2B according to the comparative example. Eliminating the wiring member 153 eliminates the parasitic inductance of the wiring member 153, improving filter performance and enabling further reduction in capacitor capacitance, thereby achieving a smaller and less costly power conversion device.

[0035] Next, another specific example of the configuration according to the first embodiment will be described with reference to FIG. 6. FIG. 6 shows an example of the arrangement of smoothing capacitors according to the first embodiment. In the example of FIG. 4, there is one second board screw fastening portion 60 between the negative electrode side conductor 70 and the board 500, whereas in the example of FIG. 6, two second board screw fastening portions 60a and 60b are provided. By providing two second board screw fastening portions 60, the first capacitor 154 can be arranged closer to the second board screw fastening portion 60 (60a, 60b), and the first capacitor and the second capacitor can be mounted between the first board screw fastening portion (first board connection portion) 50 and the two second board screw fastening portions 60 (second board connection portions). As is clear from a comparison of FIG. 4A and FIG. 6, of the two first capacitors 154, the first capacitor 154 on the left side of the drawing cannot be arranged immediately adjacent to the second board screw fastening portion 60 in FIG. 4A, whereas both first capacitors 154 are arranged immediately adjacent to the screw fastening portions in FIG. 6. 6, each of the two first capacitors 154 is disposed in close proximity to one of the two second capacitors 155. In this way, by providing two second board screw fastening portions 60 between the negative electrode side conductor 70 and the board 500, the first capacitor 154 can be disposed in closer proximity to the second board screw fastening portions 60, thereby reducing parasitic inductance and improving filter characteristics, making it possible to eliminate or reduce the number of filter components.

[0036] Furthermore, even if ripple or switching noise increases due to changes in elements or power conditions, the filter characteristics are improved by having two screw fastening points between the negative electrode conductor and the board, so ripple and switching noise can be suppressed without adding filter components and without increasing cost or size.

[0037] Next, another specific example of the configuration according to the first embodiment will be described with reference to FIG. 7. FIG. 7 shows an example of the arrangement of smoothing capacitors and board screw fastening portions (50, 60) according to the first embodiment. In FIG. 7, the board screw fastening portions (50, 60) use lug terminals (310, 320; connecting members) shown in FIG. 8, which have board connection points with the board 500 on both the left and right ends of the screw fastening points. The screw fastening portion between the positive output bus bar 170 and the board 500 is referred to as the first board screw fastening portion 50a, and the screw fastening portion between the negative conductor 70 and the board 500 is referred to as the second board screw fastening portion 60c. FIG. 7 shows the board 500, the first capacitor 154, the second capacitor 155, the first board screw fastening portion 50a, the second board screw fastening portion 60c, and the positive output bus bar 170. The lug terminal screwed to the positive output bus bar 170 is referred to as the first lug terminal 320, and the lug terminal screwed to the negative conductor is referred to as the second lug terminal 310. Of the connection points to the board 500 at both ends of the first lug terminal 320, the one closest to the board end is referred to as the first board connection point 320a, and the other is referred to as the second board connection point 320b. Of the connection points to the board at both ends of the second lug terminal 310, the one closest to the board end is referred to as the third board connection point 310a, and the other is referred to as the fourth board connection point 310b. The second capacitor 155 is mounted between the first board connection point 320a and the third board connection point 310a and between the second board connection point 320b and the fourth board connection point 310b. In this way, the first lug terminal 320 is fixed to the positive output bus bar 170 with a screw, whereby the first board screw fastening portion 50a is connected to the positive output bus bar 170 via the first lug terminal 320. Furthermore, the lug terminal 310 is fixed to the negative conductor 70 with a screw, whereby the second board screw fastening portion 60c is connected to the negative conductor 70 via the lug terminal 310. Note that the connection using the lug terminal may be made for only one of the first board screw fastening portion 50a and the second board screw fastening portion 60c.

[0038] According to this embodiment, by using lug terminals with connection points to the board on both sides of the screw fastening point, the number of connection points between the board 500 and the positive output bus bar 170 and the negative conductor 70 is increased. Furthermore, by providing two board connection points with the shortest distance and mounting a capacitor between them, the terminal thickness of the smoothing capacitor can be increased. This reduces the terminal parasitic inductance of the smoothing capacitor, improving filter performance in the high-frequency range and reducing switching noise. This allows for a more compact and cost-effective power conversion device.

[0039] In this embodiment, the positive output busbar 170 and the negative conductor 70 are fastened to the substrate 500 via the first lug terminal 320 and the second lug terminal 310, respectively. Fastening them with screws increases the contact area between the positive output busbar 170 and the negative conductor and the first lug terminal 320 and the second lug terminal 310, respectively, and reduces the parasitic inductance between the positive output busbar 170 and the negative conductor 70 and the smoothing capacitor. This improves filter performance in the high-frequency range and reduces switching noise. This allows for a more compact and cost-effective power conversion device.

[0040] Embodiment 2 Next, a circuit configuration of a power conversion device 1M according to a second embodiment will be described with reference to FIG. 9. FIG. 9 is a circuit configuration diagram of a power conversion device 1M according to a second embodiment of the present disclosure. The circuit configuration diagram of the power conversion device 1M according to the second embodiment differs from the circuit configuration diagram of FIG. 3 of the first embodiment in that the smoothing capacitors are configured in series. In FIG. 9, the second capacitor is configured in series with capacitors 156 and 157, and the first capacitor is configured in series with capacitors 158 and 159. When an SMD (Surface Mount Device) ceramic capacitor is selected as the capacitor connected in parallel with the load, the capacitor failure mode is a short circuit failure. To prevent such a capacitor short circuit from occurring, the capacitors are configured in series. Connecting the capacitors in series increases the distance from the positive output bus bar 170 to GND. However, since the second capacitor has a smaller volume than the first capacitor, the effect on the terminal length of the smoothing capacitor is small, and filter performance can be maintained. The configuration other than the smoothing capacitor is the same as that of FIG. 3, which is the circuit configuration diagram of the first embodiment, and therefore description thereof will be omitted. According to the second embodiment, by connecting the smoothing capacitors in series, it is possible to improve reliability and maintain the same filter performance as in the first embodiment.

[0041] Embodiment 3 Next, a circuit configuration of a power converter 1MM according to a third embodiment will be described with reference to FIG. 10 . FIG. 10 is a circuit configuration diagram of a power converter 1MM according to the third embodiment of the present disclosure. The circuit configuration diagram of the power converter 1MM according to the third embodiment is modified from the circuit configuration diagram of FIG. 3 of the first embodiment by adding a ferrite core 171 and a capacitor 172 between connection point 30 and a positive output connection point 40, which is a connection point between connection point 30 and a first board screw fastening portion 50 of a positive output bus bar 170. Since a smoothing reactor 151 is also connected to connection point 30, the ferrite core 171 is connected to the positive output of the power conversion circuit 10 at connection point 20 via the smoothing reactor 151. The ferrite core 171 is installed so as to be pierced by the positive output bus bar 170, and the capacitor 172 is connected between a branch point 173 between connection point 30 and ferrite core 171 and GND2.

[0042] 3, which is the circuit configuration diagram of embodiment 1, the configuration other than ferrite core 171 and capacitor 172 will not be described. According to this embodiment, even if switching noise increases due to an element change or a specification change, the added ferrite core 171 and capacitor 172 can improve filter performance, and since the smoothing circuit section is small even when parts are added, it is possible to achieve a smaller and less costly power conversion device.

[0043] Furthermore, the size of the first capacitor in the first to third embodiments may be a capacitor with a size of 3216 mm (3.2 mm × 1.6 mm) or more and 3225 mm (3.2 mm × 2.5 mm) or less. As described above, a capacitor with a high capacitance density is selected as the first capacitor to suppress ripple. Because the capacitance density of a capacitor is basically proportional to its size, a large capacitor is used as the first capacitor. However, as the size increases, the vibration resistance when mounted on a board decreases. As described above, adding structural components to counter vibration increases costs. Therefore, a capacitor with a size of 3216 mm (3.2 mm × 1.6 mm) or more and 3225 mm (3.2 mm × 2.5 mm) or less may be selected as the first capacitor, as it does not require vibration countermeasures and has a high capacitance density. By using such a capacitor, it is possible to ensure the capacitance required for ripple suppression without requiring additional components for vibration countermeasures, thereby achieving a more inexpensive filter configuration.

[0044] The second capacitor may be a capacitor with dimensions greater than 1005 (1.0 mm × 0.5 mm) and less than 1608 (1.6 mm × 0.8 mm). As mentioned above, the second capacitor emphasizes high-frequency filter characteristics to suppress switching noise. To achieve this, parasitic inductance must be minimized. Furthermore, since the first board screw fastening portion 50 and the second board screw fastening portion 60 are preferably located as close as possible to each other, it is preferable that the second capacitor between these screw fastening portions be small. However, a capacitor smaller than 1005 (1.0 mm × 0.5 mm) is likely to be damaged by board distortion or vibration. Therefore, a capacitor with dimensions greater than 1005 (1.0 mm × 0.5 mm) and less than 1608 (1.6 mm × 0.8 mm) that maintains high reliability may be selected as the second capacitor. This minimizes parasitic inductance and realizes a more inexpensive filter configuration.

[0045] <Additional Notes> Some aspects of the various embodiments described above are summarized below.

[0046] (Appendix 1) The power conversion device (1; 1M; 1MM) of Supplementary Note 1 is a power conversion device (1) comprising: a power conversion circuit (10) including a plurality of semiconductor elements; a smoothing circuit section (150) including a plurality of output capacitors (154, 155), a positive electrode side conductor (170) having at least one bent structure, and a negative electrode side conductor (70); a positive electrode side output terminal (200), a negative electrode side output terminal (GND2), and a substrate (500) having a first substrate connection portion (50) and at least one second substrate connection portion (60); one end of the positive electrode side conductor is connected to a positive electrode side output of the power conversion circuit (connection point 20), the other end of the positive electrode side conductor is connected to the positive electrode side output terminal (200), and one end of the negative electrode side conductor is connected to a negative electrode side output of the power conversion circuit (second substrate connection portion); The other end of the negative electrode side conductor is connected to the negative electrode side output terminal, the multiple output capacitors are mounted on the board, one end of each output capacitor is connected to the positive electrode side conductor at a first board connection portion and the other end of each output capacitor is connected to the negative electrode side conductor at at least one second board connection portion, the multiple output capacitors include one or more first capacitors (155) and one or more second capacitors (154) smaller in size than the first capacitors, the shortest distance (A) on the board between the first board connection portion and the second board connection portion is shorter than the inter-terminal length (C) of the first capacitor and longer than the inter-terminal length (B) of the second capacitor, and the second capacitor is mounted between the first board connection portion and the second board connection portion.

[0047] (Appendix 2) The power conversion device (1;1M;1MM) of Supplementary Note 2 is the power conversion device described in Supplementary Note 1, wherein the resonant frequency of the second capacitor is higher than the resonant frequency of the first capacitor.

[0048] (Appendix 3) The power conversion device (1; 1M; 1MM) of Supplementary Note 3 is the power conversion device described in Supplementary Note 1 or 2, wherein the first capacitor and the second capacitor are both ceramic capacitors.

[0049] (Appendix 4) The power conversion device (1M) of Appendix 4 is a power conversion device described in any one of Appendixes 1 to 3, wherein the one or more first capacitors include two or more capacitors (158, 159) connected in series, and the one or more second capacitors include two or more capacitors (156, 157) connected in series.

[0050] (Appendix 5) The power conversion device (1;1M;1MM) of Appendix 5 is a power conversion device described in any one of Appendixes 1 to 4, wherein the size of the first capacitor is 3.2mm x 1.6mm or more and 3.2mm x 2.5mm or less, and the size of the second capacitor is 1.0mm x 0.5mm or more and 1.6mm x 0.8mm or less.

[0051] (Appendix 6) The power conversion device (1; 1M; 1MM) of Appendix 6 is a power conversion device described in any one of Appendixes 1 to 5, and further includes a connection member (310, 320) having connection points with the substrate at both ends, and the connection member is fixed to the positive electrode side conductor with a screw, thereby connecting the first substrate connection portion to the positive electrode side conductor via the connection member, or the connection member is fixed to the negative electrode side conductor with a screw, thereby connecting the second substrate connection portion to the negative electrode side conductor via the connection member.

[0052] (Appendix 7) The power conversion device (1;1M;1MM) of Appendix 7 is a power conversion device described in any one of Appendixes 1 to 6, wherein the first capacitor is mounted in close proximity to the first substrate connection portion and the second substrate connection portion.

[0053] (Appendix 8) The power conversion device (1;1M;1MM) of Appendix 8 is a power conversion device described in any one of Appendixes 1 to 7, wherein the first capacitor and the second capacitor are mounted in the same orientation relative to the substrate.

[0054] (Appendix 9) The power conversion device (1;1M;1MM) of Appendix 9 is a power conversion device described in any one of Appendixes 1 to 8, wherein the at least one second substrate connection portion includes two or more second substrate connection portions, and the first capacitor and the second capacitor are mounted between the first substrate connection portion and the two or more second substrate connection portions.

[0055] (Appendix 10) The power conversion device (1;1M;1MM) of Appendix 10 is a power conversion device described in any one of Appendixes 1 to 9, wherein the first substrate connection portion and the second substrate connection portion are located at the ends of the substrate.

[0056] (Appendix 11) The power conversion device (1; 1M; 1MM) of Appendix 11 is a power conversion device described in any one of Appendixes 1 to 10, wherein the positive electrode side conductor has a bent structure (300, 400) between the first substrate connection portion and the positive electrode side output of the power conversion circuit.

[0057] (Appendix 12) The power converter (1; 1M; 1MM) of Supplementary Note 12 is the power converter according to any one of Supplementary Notes 1 to 11, wherein the negative electrode side conductor is at the same potential as the housing which is GND.

[0058] (Appendix 13) The power conversion device (1MM) of Appendix 13 is the power conversion device described in any one of Appendixes 1 to 12, further comprising: a ferrite core (171) installed between a positive electrode side output (20) of the power conversion circuit and a connection point (40) of the positive electrode side conductor with the first substrate connection portion; and a capacitor (172) connecting between the positive electrode side output of the power conversion circuit and the point where the ferrite core is installed, and GND.

[0059] It is possible to combine the embodiments, and to modify or omit each embodiment as appropriate. [Industrial Applicability]

[0060] The power conversion device of the present disclosure can be used as a power conversion device for a moving body such as an electric vehicle or an aircraft. [Explanation of symbols]

[0061] 1 (1C; 1M; 1MM) power conversion device, 10 power conversion circuit, 20 connection point, 30 connection point, 40 positive side output connection point, 50 first board screw fastening portion (connection point), 60 second board screw fastening portion, 70 negative side conductor, 80 connection point, 100 DC power supply, 110 input filter circuit portion, 111 capacitor, 112 capacitor, 120 switching circuit portion, 121 to 124 switching elements, 130 transformer portion, 131 primary winding, 132 secondary winding, 140 rectifier circuit portion, 141 diode, 150 (150C) smoothing circuit portion, 151 smoothing reactor, 152 smoothing capacitor, 153 wiring member, 154 first capacitor (smoothing capacitor), 155 second capacitor (smoothing capacitor), 156 to 159 capacitor (smoothing capacitor), 160 Output filter section, 161 ferrite core, 162 capacitor, 163 branch point, 170 positive side output bus bar, 171 ferrite core, 172 capacitor, 173 branch point, 200 output terminal, 300 bending structure, 310 second lug terminal, 310a third board connection point, 310b fourth board connection point, 320 first lug terminal, 320a first board connection point, 320b second board connection point, 500 board.

Claims

1. a power conversion circuit including a plurality of semiconductor elements; a smoothing circuit unit including a plurality of output capacitors, a positive conductor having at least one bent structure, and a negative conductor; A positive output terminal; A negative output terminal; a substrate having a first substrate connection portion and at least one second substrate connection portion; A power conversion device comprising: one end of the positive conductor is connected to a positive output of the power conversion circuit, and the other end of the positive conductor is connected to the positive output terminal; one end of the negative conductor is connected to a negative output of the power conversion circuit, and the other end of the negative conductor is connected to the negative output terminal; the plurality of output capacitors are mounted on the substrate, one end of each output capacitor is connected to the positive electrode side conductor at a first substrate connection portion, and the other end of each output capacitor is connected to the negative electrode side conductor at at least one second substrate connection portion; the plurality of output capacitors include one or more first capacitors and one or more second capacitors smaller in size than the first capacitors; a shortest distance on the substrate between the first substrate connection portion and the second substrate connection portion is shorter than a length between terminals of the first capacitor and longer than a length between terminals of the second capacitor; the second capacitor is mounted between the first substrate connection portion and the second substrate connection portion; Power conversion device.

2. The power conversion device according to claim 1 , wherein the resonant frequency of the second capacitor is higher than the resonant frequency of the first capacitor.

3. 3. The power conversion device according to claim 2, wherein the first capacitor and the second capacitor are both ceramic capacitors.

4. the one or more first capacitors comprise two or more capacitors connected in series; the one or more second capacitors comprise two or more capacitors connected in series; 4. The power conversion device according to claim 3.

5. the size of the first capacitor is equal to or greater than 3.2 mm x 1.6 mm and equal to or less than 3.2 mm x 2.5 mm; The size of the second capacitor is 1.0 mm x 0.5 mm or more and 1.6 mm x 0.8 mm or less.

4. The power conversion device according to claim 3.

6. a connecting member having connection points with the substrate at both ends; The connection member is fixed to the positive electrode-side conductor with a screw, thereby connecting the first board connection portion to the positive electrode-side conductor via the connection member, or the connecting member is fixed to the negative electrode-side conductor with a screw, whereby the second board connecting portion is connected to the negative electrode-side conductor via the connecting member.

4. The power conversion device according to claim 3.

7. The power conversion device according to claim 1 , wherein the first capacitor is mounted in close proximity to the first substrate connection portion and the second substrate connection portion.

8. The power conversion device according to claim 1 , wherein the first capacitor and the second capacitor are mounted in the same direction on the substrate.

9. A power conversion device described in any one of claims 1 to 6, wherein the at least one second substrate connection portion includes two or more second substrate connection portions, and the first capacitor and the second capacitor are mounted between the first substrate connection portion and the two or more second substrate connection portions.

10. The power conversion device according to claim 1 , wherein the first substrate connection portion and the second substrate connection portion are located at ends of the substrate.

11. the positive electrode conductor has a bent structure between the first substrate connection portion and the positive electrode output of the power conversion circuit. The power conversion device according to any one of claims 1 to 6.

12. The power conversion device according to claim 1 , wherein the negative electrode side conductor has the same potential as the housing, which is GND.

13. a ferrite core disposed between a positive electrode output of the power conversion circuit and a connection point between the positive electrode conductor and the first substrate connection portion; a capacitor connecting a point where the positive output of the power conversion circuit and the ferrite core are installed to GND; The power conversion device according to claim 1 , further comprising:

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