Filtering device and power conversion device

Abstract

A filter device includes a π-type noise filter having a magnetic core surrounding a direct current wiring, a first capacitor at a front stage of the magnetic core, and a second capacitor at a rear stage of the magnetic core, and a metal housing having a first ground point and a second ground point. The first capacitor and the second capacitor are connected to the first ground point and the second ground point, respectively, and a first partition wall and a second partition wall are formed to face each other with a predetermined gap therebetween. A power conversion device includes the filter device and a power conversion unit.

Description

Technical Field

[0001] This invention relates to a filtering device and a power conversion device. Background Technology

[0002] Power conversion devices installed in hybrid or electric vehicles must meet the individual standards set by each automaker to address conducted noise generated by leakage current, based on high-voltage conducted noise standards added to international standards. Meanwhile, with the development of electric vehicles equipped with power conversion devices, the demands for miniaturization and cost reduction have increased significantly in recent years. Therefore, there is a strong requirement for the filtering devices in power conversion devices to achieve both improved high-frequency noise attenuation performance and cost reduction and miniaturization.

[0003] As background technology for this application, the following patent document 1 is known. Patent document 1 discloses a configuration that allows the disconnection of a line capacitor and a ground capacitor connected to the input and output sides of a common-mode choke, respectively, by adding a switch. Furthermore, patent document 2 discloses a device that intentionally uses a capacitor parasitic on an insulating substrate on which power semiconductor elements are mounted, and by forming an inductor and a parallel resonator configuration, can suppress electromagnetic radiation caused by common-mode current.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2017-118387

[0007] Patent Document 2: Japanese Patent Application Publication No. 2004-088936 Summary of the Invention

[0008] The problem the invention aims to solve

[0009] The technology in Patent Document 1 is achieved by adding components, thus improving high-frequency noise attenuation performance, but it cannot achieve cost reduction and miniaturization. Furthermore, the technology in Patent Document 2 cannot sufficiently improve high-frequency noise attenuation performance, and therefore may not meet the requirements of the standards.

[0010] Therefore, the objective of this invention is to provide a filter device and a power conversion device that can achieve low cost and miniaturization while improving high-frequency noise attenuation performance.

[0011] Technical means to solve the problem

[0012] The filtering device of the present invention includes: a π-type noise filter; and a metal housing having a first ground point and a second ground point. The π-type noise filter comprises: a magnetic core surrounded by a DC wiring including positive and negative terminals; a first capacitor connected to the DC wiring at the front end of the magnetic core; and a second capacitor connected to the DC wiring at the rear end of the magnetic core. The first capacitor and the second capacitor are respectively connected to the first ground point and the second ground point. In the metal housing, a first partition wall and a second partition wall are formed between the first ground point and the second ground point, facing each other, with a predetermined gap between the first partition wall and the second partition wall. A power conversion device includes a power conversion section that converts a DC voltage input via the filtering device into an AC voltage.

[0013] The effects of the invention

[0014] According to the present invention, a filter device and a power conversion device can be provided that can improve high-frequency noise attenuation performance while achieving low cost and miniaturization. Attached Figure Description

[0015] Figure 1 This is a block diagram showing the configuration of a power conversion device.

[0016] Figure 2 This is a circuit diagram showing the equivalent circuit of a π-type noise filter.

[0017] Figure 3 This is a graph showing the insertion loss of a π-type noise filter.

[0018] Figure 4 This is a diagram showing the structure of the π-type noise filter according to the first embodiment of the present invention.

[0019] Figure 5 It is shown Figure 4 The circuit diagram of the equivalent circuit of the π-type noise filter.

[0020] Figure 6 It is shown Figure 5 A graph showing the insertion loss of a π-type noise filter.

[0021] Figure 7 This is a diagram showing the structure of the π-type noise filter according to the second embodiment of the present invention.

[0022] Figure 8 This is a diagram showing the structure of a π-type noise filter according to a third embodiment of the present invention.

[0023] Figure 9 This is a diagram showing the structure of the π-type noise filter according to the fourth embodiment of the present invention.

[0024] Figure 10 This is a diagram showing the structure of the π-type noise filter according to the fifth embodiment of the present invention.

[0025] Figure 11 This is a diagram showing the structure of the π-type noise filter according to the sixth embodiment of the present invention. Detailed Implementation

[0026] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Furthermore, the embodiments are merely examples for illustrating the present invention, and appropriate omissions and simplifications have been made for clarity. The present invention can be implemented in various other forms. Unless otherwise specified, the constituent elements can be singular or plural. Additionally, for ease of understanding, the positions, sizes, shapes, extents, etc., of the constituent elements shown in the figures sometimes do not represent actual positions, sizes, shapes, extents, etc. Therefore, the present invention is not limited to the positions, dimensions, shapes, extents, etc., disclosed in the drawings.

[0027] When multiple constituent elements have the same or identical functions, different subscripts are sometimes added to the same symbols for explanation. Conversely, when it is not necessary to distinguish these multiple constituent elements, the subscripts are sometimes omitted for explanation.

[0028] (Composition of a power conversion device)

[0029] Figure 1 This is a block diagram illustrating the configuration of the power conversion device of the present invention.

[0030] The power conversion device 1 (hereinafter referred to as inverter 1) stores various circuit blocks and components. In addition, inverter 1 is connected to high-voltage battery 2 that supplies DC high voltage and motor 6 that is driven by AC voltage, which is converted from DC voltage by inverter 1.

[0031] The inverter 1 has a metal casing that is connected to the GND plane 9 via GND strip 8 in accordance with international standard CISPR 25 and is mounted on an insulator 7 5mm high.

[0032] Inverter 1 includes a switching circuit 14 for converting DC voltage to AC voltage. The switching circuit 14 includes three unit switching circuits SW1 to SW3 with identical configurations, and these circuits are periodically switched. Furthermore, each unit switching circuit SW1 to SW3 includes an insulated-gate bipolar transistor (hereinafter referred to as a transistor) TR1, TR2, and diodes D1 and D2. Additionally, although not shown, inverter 1 includes a control circuit board that generates control signals for the switching circuit 14.

[0033] Diodes D1 and D2 are connected between the collector and emitter of transistors TR1 and TR2, respectively. The collector of transistor TR1 is electrically connected to the positive terminal wiring 11, which serves as a DC wiring, and the emitter of transistor TR2 is electrically connected to the negative terminal wiring 12, which also serves as a DC wiring. The emitter of transistor TR1 is connected to the collector of transistor TR2. Furthermore, the connection point between the emitter and collector is the output node, which is connected from each unit switching circuit SW1 to SW3 to the coils 6-U to 6-W of the motor 6 via high-voltage AC cables 5.

[0034] The flow of control signals for inverter 1 will be explained. Switching control signals from a control circuit board (not shown) are provided to the gates of transistors TR1 and TR2 in the unit switching circuits SW1 to SW3. These switching control signals control the switching of transistors TR1 and TR2, causing them to be complementaryly turned on / off. Furthermore, by complementaryly turning on / off, transistors TR1 and TR2 periodically output positive and negative voltages, i.e., AC voltages, to the output node.

[0035] Furthermore, due to the voltage fluctuations at the output caused by the periodic switching on / off of transistors TR1 and TR2, parasitic capacitance is generated between the switching circuit 14 and the casing of the inverter 1. Figure 1 In this context, the parasitic capacitance is denoted as parasitic capacitance 1-Cs.

[0036] The high-voltage power supply impedance stabilization network (LISN) 3 will be described. The high-voltage battery 2 supplies power to the inverter 1 through the high-voltage power supply impedance stabilization network (LISN) 3. The housing 3 has a positive LISN circuit section 31 connected to the positive electrode terminal HVP of the high-voltage battery 2 and a negative LISN circuit section 32 connected to the negative electrode terminal HVN of the high-voltage battery 2; these are housed within a metal housing. The housing of LISN 3 is connected to the GND plane 9. The positive LISN circuit section 31 and the negative LISN circuit section 32 are electrically connected to the positive wiring 11 and the negative wiring 12, which are DC wiring of the inverter 1, via a high-voltage DC cable 4.

[0037] The motor 6 is described below. Motor 6 is a three-phase motor, having a rotor and stator (not shown). The housing of motor 6 is connected to the GND plane 9. Motor 6 supplies the three-phase AC voltage generated by inverter 1 to the three-phase coils 6-U, 6-V, and 6-W, U, V, and W, arranged on the stator, via high-voltage AC cable 5. As a result, the three-phase coils 6-U, 6-V, and 6-W each generate a magnetic field corresponding to the three-phase AC voltage, causing the rotor to rotate. Furthermore, in... Figure 1 In the diagram, the parasitic capacitance generated between the three-phase coils 6-U, 6-V, and 6-W and the housing of the motor 6 is represented as parasitic capacitance 6-Cs.

[0038] In inverter 1, a smoothing capacitor Cx and a CLC π-type noise filter 13 are provided between the positive wiring 11 and the negative wiring 12 to smooth the DC voltage. When the switching circuit 14 is switched on, the smoothing capacitor Cx suppresses the ripple voltage or ripple current generated in the DC wirings 11 and 12, which are connected to the DC high voltage bus.

[0039] The CLCπ-type noise filter 13 has: a magnetic core Lc surrounded by DC wiring including positive wiring 11 and negative wiring 12; a first grounding capacitor Cy1 connected to the DC wiring 11 and 12 at the front end of the magnetic core Lc; and a second grounding capacitor Cy2 connected to the DC wiring 11 and 12 at the rear end of the magnetic core Lc.

[0040] At the bottom of the inverter 1 housing are formed a first grounding point G1 and a second grounding point G2 for grounding the positive wiring 11 and the negative wiring 12. The first grounding capacitor Cy1 consists of a grounding capacitor Cy11 connected between the positive wiring 11 and the first grounding point G1, and a grounding capacitor Cy12 connected between the negative wiring 12 and the first grounding point G1. Similarly, the second grounding capacitor Cy2 consists of a grounding capacitor Cy21 connected between the positive wiring 11 and the second grounding point G2, and a grounding capacitor Cy22 connected between the negative wiring 12 and the second grounding point G2.

[0041] The CLCπ-type noise filter 13 attenuates the noise from the DC high voltage supplied from the high-voltage battery 2, while simultaneously inputting DC high voltage to the switching circuit 14, which serves as a power conversion unit. The noise current that causes the noise is the leakage current in the power wiring or cable connected between the DC high-voltage battery 2 and the inverter 1, and is the common-mode current flowing between GND.

[0042] Common-mode current is the current caused by voltage fluctuations to ground generated when transistors TR1 and TR2 periodically switch between on and off states. Due to the voltage fluctuations generated at the output of the switching circuit 14, a common-mode current flows between the inverter 1 and the motor 6 housing through parasitic capacitance 1-Cs between the switching circuit 14 and the inverter 1 housing, and parasitic capacitance 6-Cs between the coils 6-U to W of the motor 6 and the housing, generating high-voltage conducted noise. Therefore, to reduce high-voltage conducted noise, it is necessary to reduce the common-mode current. In the inverter 1, by using a CLCπ-type noise filter 13, noise is attenuated in a manner corresponding to the noise current, which is the main cause of high-voltage conducted noise, and also in accordance with high-voltage conducted noise standards.

[0043] This section explains the high-voltage conducted noise standard. Noise standards generally specify limits in the frequency band from 0.15 MHz to 108 MHz. The high-voltage conducted noise standard is a standard added to CISPR 25 Ed4, an international standard created by the International Special Committee on Radio Interference (CISPR) in October 2016. Its content limits the noise in the FM broadcasting band (76 MHz to 108 MHz), particularly for various applications, to be lower than in other frequency bands.

[0044] As mentioned above, the high-voltage conducted noise generated may cause malfunctions in the vehicle's electrical and electronic equipment. Therefore, before leaving the factory, the amount of high-voltage conducted noise generated in inverter 1 is measured, and this noise level must be below the values ​​specified by the laws of various countries and customer requirements. Therefore, in order to meet the high-voltage conducted noise standards and become an effective filter configuration, inverter 1 adopts a CLCπ-type noise filter 13.

[0045] Figure 2 This is a circuit diagram showing the equivalent circuit of the π-type noise filter 13 in the comparative example. Figure 2 In the figure, as a comparative example, an equivalent circuit diagram is shown when the structure of the present invention is not applied in the π-type noise filter 13.

[0046] Figure 2 The equivalent circuit diagram is used to calculate the insertion loss of the π-type noise filter. It is also the equivalent circuit of the high-voltage power supply impedance stabilization network (LISN) 3 and the switching circuit 14 mentioned above.

[0047] Power supply Gn is an AC voltage source for the noise voltage generated in analog switching circuit 14, and V1 is a voltmeter for measuring power supply Gn. Additionally, Figure 1 The LISN3 can be equivalent to an internal resistance in the high-frequency band, therefore in Figure 2 The resistor is represented as R4. V2 is a voltmeter used to measure the voltage across resistor R4.

[0048] The first grounding capacitor Cy1 and the second grounding capacitor Cy2 are electrically connected to the DC wiring BSB of inverter 1. In addition, in the case of common-mode noise current, which is the main cause of noise, they are equivalently connected in parallel between the DC wiring and the housing. Therefore, in the equivalent circuit diagram, the first grounding capacitor Cy1 and the second grounding capacitor Cy2 are depicted as being connected between the DC wiring and the housing.

[0049] exist Figure 2In this diagram, Lc represents the inductance of the magnetic core Lc. Lg1, Lg2, and Lg3 represent the inductances between grounding point G1 and the inverter 1 housing, grounding point G2 and the inverter 1 housing, and grounding point G1 and grounding point G2, respectively. The asterisk (*) markings on Lg1 and Lg2 indicate the direction of magnetic field generation. Additionally, k2 represents the coupling coefficient (hereinafter referred to as the coupling coefficient) between inductors Lg1 and Lg2. Furthermore, the parasitic inductances of the wiring to LISN3 (including wiring or cables), the parasitic inductances of the leads of capacitor elements Cy11, Cy12, Cy21, and Cy22, and the inductance of the path of the wiring from the inverter 1 housing to LISN3 are omitted from the display.

[0050] Figure 3 It is shown Figure 2 The graph shows the insertion loss of a miniaturized π-type noise filter. The horizontal axis represents frequency F, and the vertical axis represents decibels (dBV). Figure 2 The ratio of voltages V2 to V1 is shown.

[0051] As described above, the π-type noise filter 13 has the effect of reducing common-mode current. Its reduction effect or attenuation performance is typically represented by the filter's insertion loss. The mechanism for reducing common-mode current in the π-type noise filter 13 is as follows: a low-impedance path is established between the positive terminal wiring 11 and the negative terminal wiring 12 and the GND plane 9 through the first grounding capacitor Cy1 and the second capacitor Cy2. This causes the common-mode current to bypass from the positive terminal wiring 11 and the negative terminal wiring 12 to the GND plane 9, reducing the amount of current leaking between the inverter 1 and the motor 6 housings. On the other hand, magnetic flux is generated by the current flowing through the aforementioned low-impedance path, and these magnetic fluxes link together, thereby generating inductive coupling. The degree of inductive coupling is represented by the aforementioned coupling coefficient k2.

[0052] exist Figure 3 In this context, a smaller ratio of voltages V2 to V1 indicates higher insertion loss and better noise attenuation performance of the filter. Characteristic curve GLb1 represents the change in insertion loss with frequency F when the coupling coefficient k2 of inductors Lg1 and Lg2 is 0.08. On the other hand, characteristic curve GLb0 represents the change in insertion loss when the coupling coefficient k2 of inductors Lg1 and Lg2 is 0.256, assuming grounding points G1 and G2 are positioned close together due to miniaturization of the power conversion device. Furthermore, the parameters of the circuit components other than k2 are the same when characteristic curves GLb0 and GLb1 are obtained.

[0053] like Figure 3As shown, compared to the characteristic curve GLb1 when the coupling coefficient k2 of inductors Lg1 and Lg2 is 0.08, the ratio of voltage V2 to V1 in the characteristic curve GLb1 when the coupling coefficient k2 is 0.256 is higher. Here, when grounding points G1 and G2 are configured separately, the inductive coupling is extremely weak, and the coupling coefficient k2 decreases to below 0.1. However, with the miniaturization of inverter 1, if the configuration of the first grounding capacitor Cy1 and the second grounding capacitor Cy2 of the π-type noise filter 13 is close, the coupling coefficient k2 increases accordingly. Therefore, it can be seen that due to the miniaturization of the π-type noise filter 13 accompanying the miniaturization of inverter 1, the filter insertion loss in the high-frequency band including the FM band decreases, and the noise attenuation performance deteriorates.

[0054] Therefore, in this invention, by adopting the structure described in the following embodiments, even if the π-type noise filter 13 is miniaturized, the reduction of filter insertion loss in the high-frequency band can be suppressed, and the deterioration of noise attenuation performance can be prevented.

[0055] (First Embodiment)

[0056] Figure 4 This is a diagram showing the structure of the π-type noise filter 13 according to the first embodiment of the present invention. Figure 4 (a) is a schematic diagram showing the structure of the π-type noise filter according to the first embodiment of the present invention. Figure 4 (b) is a perspective view of the π-type noise filter 13 according to the first embodiment of the present invention, showing an example of the three-dimensional structure.

[0057] like Figure 4 (a) and Figure 4 As shown in (b), in this embodiment, at the bottom of the inverter 1 housing, opposing partitions W1 and W2 are formed between grounding points G1 and G2 with a predetermined gap. Furthermore, in the circuit modules and components housed in the inverter 1 housing, only the positive DC wiring 11, negative DC wiring 12, magnetic core Lc, first grounding capacitor Cy1, and second grounding capacitor Cy2 are shown; other parts are omitted.

[0058] like Figure 4 As shown, the π-type noise filter 13 of this embodiment is characterized by including a first partition wall W1 and a second partition wall W2 that are opposite to each other. The first partition wall W1 and the second partition wall W2 can be formed by machining a shell made of conductive metal by cutting or the like, or they can be integrally formed when the shell is formed by casting.

[0059] Figure 5 This illustrates the first embodiment of the present invention. Figure 4 The circuit diagram of the equivalent circuit of the π-type noise filter. Additionally, Figure 5 and Figure 2 Similarly, this is the equivalent circuit used to calculate the insertion loss of the noise filter, where capacitor Cp is the parasitic capacitance between the first partition W1 and the second partition W2. Other circuit components and circuit diagram contents are the same as... Figure 2 same.

[0060] like Figure 5 As shown, by setting partitions W1 and W2, the parasitic capacitance between the partitions is intentionally used to form a parallel resonator with the parasitic inductances Lg1, Lg2, and Lg3 on the ground plane. This improves the noise attenuation performance of the π-type noise filter.

[0061] Figure 6 It is shown Figure 5 The diagram shows the insertion loss of the π-type noise filter. Figure 6 and Figure 3 Similarly, the horizontal axis represents frequency F, and the vertical axis represents decibels (dBV). Figure 5 The ratio of voltages V2 to V1 is shown. This means that the smaller the ratio of voltages V2 to V1, the higher the insertion loss of the filter and the better the noise attenuation performance.

[0062] Characteristic curve GLb2 represents the change in insertion loss with frequency F when the parasitic capacitance Cp on the partitions W1 and W2 is 50 pF. On the other hand, characteristic curve GLb0 represents the insertion loss when there is no parasitic capacitance Cp on the partitions W1 and W2 (and...). Figure 3 The change in insertion loss is calculated when GLb0 is the same. Furthermore, the parameters of the circuit components other than the parasitic capacitance Cp are the same when the characteristic curves GLb0 and GLb2 are obtained.

[0063] As described above, by intentionally using the parasitic capacitor Cp in the partition wall, and utilizing the parasitic inductance of the path from the first grounding point G1 to the second grounding point G2 to form a parallel resonator, the noise attenuation performance in the high-frequency band can be improved. The resonant frequency fp can be obtained by equation (1).

[0064] [Formula 1]

[0065]

[0066] In equation (1), as mentioned above, parasitic capacitance Cp represents the capacitance of parasitic capacitances parasitic on adjacent walls W1 and W2, Lg1~Lg3 represent the parasitic inductance of the path from the first grounding point G1 to the second grounding point G2, and k2 represents the coupling coefficient of inductances Lg1 and Lg2.

[0067] As shown in equation (1), the resonant frequency fp is obtained based on the values ​​of parasitic capacitance Cp and parasitic inductance Lg1, Lg2, and Lg3. Furthermore, the value of parasitic capacitance Cp can be adjusted based on the distance between partitions W1 and W2, the area of ​​the opposing walls of partitions W1 and W2, or the dielectric constant between partitions W1 and W2. Thus, the resonant frequency fp can be shifted to the desired frequency band for improving the attenuation performance of the filter.

[0068] That is, by setting partitions W1 and W2 at the bottom of the inverter 1's casing, for a specific target frequency band, the maximum attenuation performance can be achieved by adjusting the values ​​of parasitic capacitance Cp and parasitic inductance, thus realizing miniaturization without the need for additional components. Furthermore, this allows for pre-design to achieve the maximum attenuation performance during the product design phase. Therefore, cost reduction and miniaturization of the filtering device are realized, which in turn also enables cost reduction and miniaturization of the power conversion device.

[0069] According to the first embodiment of the present invention described above, the following effects are achieved.

[0070] (1) The filtering device includes a π-type noise filter 13 and a metal housing 1 having a first grounding point G1 and a second grounding point G2. The π-type noise filter 13 includes: a magnetic core Lc surrounded by DC wiring including a positive terminal wire 11 and a negative terminal wire 12; a first capacitor Cy1 connected to the DC wiring 11 and 12 at the front end of the magnetic core Lc; and a second capacitor Cy2 connected to the DC wiring 11 and 12 at the rear end of the magnetic core Lc. The first capacitor Cy1 and the second capacitor Cy2 are respectively connected to the first grounding point G1 and the second grounding point G2. In the metal housing 1, a first partition wall W1 and a second partition wall W2 are formed between the first grounding point G1 and the second grounding point G1, and a predetermined gap is formed between the first partition wall W1 and the second partition wall W2. Thus, a filtering device that balances low cost, miniaturization, and improved high-frequency noise attenuation performance can be provided.

[0071] (2) The power conversion device includes a filter and a power conversion section that converts the DC voltage input through the filter into AC voltage. As a result, the power conversion device with a filter that improves high-frequency noise attenuation performance can be made both low-cost and miniaturized.

[0072] (Second Implementation)

[0073] Figure 7 This is a diagram showing the structure of the π-type noise filter 13 according to the second embodiment of the present invention.

[0074] This embodiment has a structure in which an insulating member 100 is provided between the first partition W1A and the second partition W2A, which are opposite each other, in the inverter 1A. The insulating member 100 is a dielectric such as a resin component. Since the dielectric constant of the insulating member 100 is higher than that of air, the variable range of the parasitic capacitance between the first partition W1A and the second partition W2A is larger than that in the case where the insulating member 100 is not placed between the partitions W1A and W2A. In addition, by applying formula (1), the variable range of the parasitic capacitance Cp and the parasitic inductance can be adjusted, thereby further expanding the variable range of the resonant frequency fp.

[0075] This configuration allows for greater design flexibility. For example, the dielectric 100 disposed between partitions W1A and W2A can be pre-embedded integrally with the metal housing 1A, or it can be inserted after installation. Furthermore, the insulating member 100 can also be adapted to use insulating materials other than resin.

[0076] According to the second embodiment of the present invention described above, the following effects are achieved.

[0077] (3) The filter device has an insulating member 100 between the first partition W1A and the second partition W2A. Compared with the case where the insulating member 100 is not used, this configuration can improve the attenuation performance of the π-type noise filter.

[0078] (Implementation methods 3 to 6).

[0079] Figures 8-11 This is a diagram showing the structure of the π-type noise filter according to embodiments 3 to 6 of the present invention.

[0080] Figure 8 In this configuration, portions of the opposing surfaces of the first partition wall W1B and the second partition wall W2B protrude. Thus, as long as the opposing surfaces of the partition walls have the same area, regardless of their shape, they can achieve the same effect. Therefore, in Figure 8 The image shows a portion of its protrusion bent at a 90-degree angle, but it could also be in other shapes.

[0081] For example, such as Figure 9 As shown, the first partition W1C and the second partition W2C can also be configured as parallel flat plates with different thicknesses. Alternatively, the partitions can be curved. Furthermore, they do not necessarily need to be parallel, as long as the desired capacitance value can be obtained. Figure 10 As shown, it can also be a shape in which either of the opposing faces of the first partition wall W1D and the second partition wall W2D forms an inclined shape.

[0082] In addition, such as Figure 11As shown, the opposing surfaces of the first partition wall W1E and the second partition wall W2E can also be formed into a conical shape. In this case, when forming the partition walls W1E and W2E by casting, a conical shape can be formed by leaving an angle after removing the mold.

[0083] According to the 3rd to 6th embodiments of the present invention described above, the following effects are achieved.

[0084] (4) The areas of the opposing surfaces of the first partition wall W1B~E and the second partition wall W2B~E of the filter device are the same. This increases the degree of freedom in the design during the formation of the partition wall.

[0085] Furthermore, the above description is merely an example, and in explaining the invention, there are no limitations or constraints on the correspondence between the matters described in the above embodiments and the matters described in the claims. For example, in the above embodiments, an electric power conversion device mounted on a vehicle such as a hybrid electric vehicle or an electric vehicle has been described as an example, but the present invention is not limited to this and can also be applied to electric power conversion devices used in construction machinery or railway vehicles, etc. In addition, deletions, substitutions of other components, and additions of other components can be made without departing from the technical concept of the invention, and such methods are also included within the scope of the present invention.

[0086] Symbol Explanation

[0087] 1…Power conversion device (inverter)

[0088] 2…High-voltage battery

[0089] 3…High Voltage Impedance Stabilization Network (LISN)

[0090] 31…Positive LISN Circuit Section

[0091] 32… Negative LISN Circuit Section

[0092] 4…High-voltage DC cable

[0093] 5…High-voltage AC cable

[0094] 6-U…U phase coil

[0095] 6-V…V phase coil

[0096] 6-W…W phase coil

[0097] 6-Cs… Parasitic capacitance between coil and housing

[0098] 7…Insulator

[0099] 8…GND band

[0100] 9…GND plane

[0101] 11… Positive DC wiring

[0102] 12… Negative DC wiring

[0103] 13…π type noise filter

[0104] 14…Switching circuit

[0105] 1-Cs… Switching circuit · Inter-casing parasitic capacitance

[0106] 100…dielectric

[0107] SW1~SW3… Unit switch circuit

[0108] TR1, TR2... Insulated Gate Bipolar Transistors

[0109] Diodes D1, D2...

[0110] Cx…smoothing capacitor

[0111] Lc…Magnetic Core

[0112] Cy1…First Grounding Capacitor

[0113] Cy2…First Grounding Capacitor

[0114] Cy11, Cy21… Positive DC wiring and grounding capacitors between casings

[0115] Cy12, Cy22… Negative DC wiring, grounding capacitor between casings

[0116] G1…First grounding point

[0117] G2…Second grounding point

[0118] BSB…DC wiring

[0119] W1~W3… next door.

Claims

1. A filtering device, characterized in that, Possessing: a π-type noise filter; and a metal case in which a first ground point and a second ground point are formed, the π-type noise filter has: a magnetic core that surrounds a direct current wiring including a positive electrode wiring and a negative electrode wiring; a first capacitor that is connected to the direct current wiring at a front stage of the magnetic core; and a second capacitor that is connected to the direct current wiring at a rear stage of the magnetic core, the first capacitor and the second capacitor are connected to the first ground point and the second ground point, respectively, in the metal case, a first partition wall and a second partition wall that face each other are formed between the first ground point and the second ground point, a prescribed gap is provided between the first partition wall and the second partition wall, and a parasitic capacitor is parasitically present.

2. The filter device according to claim 1, characterized in that, an insulating member is provided between the first partition wall and the second partition wall.

3. The filter device according to claim 1 or 2, characterized in that, areas of the mutually facing surfaces of the first partition wall and the second partition wall are the same.

4. A power conversion device, characterized by, Possessing: the filter device according to claim 1; and a power conversion section that converts a direct current voltage input via the filter device into an alternating current voltage.

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