Filter circuit, electric power conversion equipment

Abstract

To provide a filter circuit which can be downsized and furthermore can be improved in noise suppression effect.SOLUTION: A filter circuit 20 comprises one core 23, a first P-side coil portion 21a wound around the core 23, and a second P-side coil portion 21b wound around the core 23 and continuous with the first coil portion 21a. The filter circuit 20 also comprises a first N-side coil portion 22a wound around the core 23, and a second N-side coil portion 22b wound around the core 23 and continuous with the first coil portion 22a. The filter circuit 20 also comprises a Y capacitor 24 having one terminal connected between the first coil portion 21a and the second coil portion 21b and the other terminal grounded. The filter circuit 20 also comprises a Y capacitor 25 having one terminal connected between the first coil portion 22a and the second coil portion 22b and the other terminal grounded.SELECTED DRAWING: Figure 5

Description

[Technical Field]

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

[0002] As disclosed in Patent Document 1, there is a power conversion device provided with a noise filter. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-102913 Summary of the Invention [Problem to be solved by the invention]

[0004] A filter circuit may be configured by combining a capacitor and a core, and since the filter circuit may be equipped with multiple cores and capacitors to improve noise suppression, the overall size of the circuit may increase.

[0005] One disclosed object is to provide a filter circuit that can improve noise suppression effects while reducing the size of the circuit, and another disclosed object is to provide a power conversion device that can improve noise suppression effects while reducing the size of the circuit. [Means for solving the problem]

[0006] The filter circuit disclosed herein comprises: One core (23) and a first coil portion (21a; 22a) wound around a core; a second coil portion (21b; 22b) provided continuously with the first coil portion and wound around a core; The power supply includes a capacitor (24; 25) having one terminal connected between the first coil portion and the second coil portion and the other terminal grounded.

[0007] The filter circuit disclosed herein can be configured to have two pseudo-cores, which allows the filter circuit to be more compact than a configuration with two cores, and also provides improved noise suppression compared to a configuration with one core, one coil, and one capacitor.

[0008] The power conversion device disclosed herein comprises: A power conversion device connectable to a power source (200) and an external device (300), A low-potential power line (10N), High-potential power line (10P), a transformer circuit (40) connected to the low-potential side power line and the high-potential side power line; a filter circuit (20) provided between the power supply and the transformer circuit; The filter circuit is One core (23) and a first coil portion (21a; 22a) connected to at least one of a low-potential side power line and a high-potential side power line and wound around a core; a second coil portion (21b; 22b) provided continuously with the first coil portion and wound around a core; The power supply includes a capacitor (24; 25) having one terminal connected between the first coil portion and the second coil portion and the other terminal grounded.

[0009] The power converter disclosed herein includes a filter circuit with a reduced physical size as described above, which allows the power converter to be reduced in size. Furthermore, the power converter includes a filter circuit with an improved noise suppression effect, which also allows the power converter to have an improved noise suppression effect.

[0010] The various aspects disclosed in this specification employ different technical means to achieve their respective objectives. The reference numerals in parentheses in the claims and in this section are intended to exemplify correspondences with the following embodiments and are not intended to limit the technical scope. The objectives, features, and advantages disclosed in this specification will become more apparent by reference to the following detailed description and the accompanying drawings. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a circuit diagram showing a schematic configuration of a power conversion device according to an embodiment. [Figure 2] 1 is a plan view showing a schematic configuration of a power conversion device according to an embodiment. [Figure 3] FIG. 2 is a plan view showing a schematic configuration of a filter circuit according to an embodiment. [Figure 4] 4 is a plan view showing the filter circuit as seen from the direction of arrow IV in FIG. 2. FIG. [Figure 5] FIG. 2 is a circuit diagram illustrating a schematic configuration of a filter circuit according to an embodiment. [Figure 6] FIG. 10 is a plan view showing a modified example of the filter circuit. [Figure 7] FIG. 10 is a circuit diagram showing a modified example of the filter circuit. [Figure 8] 10 is a simulation result showing the noise suppression effect of a filter circuit. [Figure 9] 10 is a simulation result showing the noise suppression effect of a filter circuit. [Figure 10] FIG. 2 is a circuit diagram illustrating a schematic configuration of a filter circuit according to an embodiment. [Figure 11] 4 is a diagram showing impedance characteristics of a filter circuit according to an embodiment. [Figure 12] FIG. 10 is a circuit diagram illustrating a filter circuit of a comparative example. [Figure 13] 10 is a diagram showing impedance characteristics of a filter circuit of a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. The power conversion device 100 is configured to be mountable on, for example, a mobile object. Examples of the mobile object include vehicles such as electric vehicles, hybrid vehicles, and fuel cell vehicles, flying objects such as electric vertical take-off and landing aircraft and drones, ships, construction machinery, and agricultural machinery. However, the power conversion device 100 may also be mounted on devices other than mobile objects. In this embodiment, the power conversion device 100 mounted on an electric vehicle is used as an example. In the following, three mutually orthogonal axes are referred to as the X-axis, Y-axis, and Z-axis.

[0013] <Power conversion device> A power conversion device 100 will be described with reference to Figures 1 and 2. As shown in Figure 1, the power conversion device 100 is configured to be connectable to a power source 200 and a motor 300. In this embodiment, an inverter circuit is used as an example of the power conversion device 100. However, the present disclosure is not limited to this.

[0014] An on-board battery mounted on a vehicle can be used as the power source 200. In this embodiment, a motor 300 is used as an example of an external device. The motor 300 is a three-phase motor including a U-phase coil 310, a V-phase coil 320, and a W-phase coil 330.

[0015] The power conversion device 100 includes a P wiring 10P that is a high-potential side power supply line, an N wiring 10N that is a low-potential side power supply line, a transformer circuit 40 connected to the P wiring 10P and the N wiring 10N, and a filter circuit 20 provided between a power supply 200 and the transformer circuit 40. The power conversion device 100 also includes a smoothing capacitor 30 connected to the P wiring 10P and the N wiring 10N.

[0016] 2, the power conversion device 100 further includes a circuit board 50 and a housing 60. A connector 1 is attached to the housing 60. The connector 1 is connected to a power source 200.

[0017] The P wiring 10P is connected to the positive terminal of the power supply 200. The P wiring 10P includes a first P wiring section 11 provided between the power supply 200 and the filter circuit 20, and a second P wiring section 12 provided between the filter circuit 20 and the transformer circuit 40. The P wiring 10P also includes a P-side coil 21 of the filter circuit 20, which will be described later. One end of the P wiring 10P is held by the connector 1, and the other end is connected to the transformer circuit 40.

[0018] The N wiring 10N is connected to the negative terminal of the power source 200. The N wiring 10N includes a first N wiring section 13 provided between the power source 200 and the filter circuit 20, and a second N wiring section 14 provided between the filter circuit 20 and the transformer circuit 40. The N wiring 10N also includes an N-side coil 22 of the filter circuit 20. One end of the N wiring 10N is held by the connector 1, and the other end is connected to the transformer circuit 40.

[0019] The filter circuit 20 is an LCL filter. The filter circuit 20 is provided to suppress noise in the power conversion device 100. The filter circuit 20 will be described later. The noise source here is a switching element of a transformer circuit 40, which will be described later. In other words, the filter circuit 20 is a circuit for suppressing (attenuating) switching noise caused by the switching elements.

[0020] The smoothing capacitor 30 has one terminal connected to the second P wiring portion 12 and the other terminal connected to the second N wiring portion .

[0021] The transformer circuit 40 includes a U-phase power card 41, a V-phase power card 42, and a W-phase power card 43. The U-phase power card 41 has an upper arm element 40a and a lower arm element 40b, which serve as switching elements, connected in series. Although not shown, the V-phase power card 42 and the W-phase power card 43 are similarly configured.

[0022] The upper arm element 40a and the lower arm element 40b are MOSFETs. The upper arm element 40a and the lower arm element 40b are formed by forming N-channel MOSFETs as vertical elements on a semiconductor substrate made of silicon carbide (SiC). Therefore, the upper arm element 40a and the lower arm element 40b can also be called SiCMOS. However, the upper arm element 40a and the lower arm element 40b may also be formed from silicon (Si) or other materials.

[0023] A drain electrode of upper arm element 40a is connected to second P wiring portion 12. A source electrode of upper arm element 40a is connected to a drain electrode of lower arm element 40b. A drain electrode of lower arm element 40b is connected to second N wiring portion 14.

[0024] The gate electrodes of each of the arm elements 40a, 40b are connected to a circuit board 50. The circuit board 50 includes a control circuit that controls the on / off state of each of the arm elements 40a, 40b. Therefore, the upper arm element 40a and the lower arm element 40b are controlled to be on / off by a control signal from the circuit board 50.

[0025] In U-phase power card 41, a U-phase line 15 is connected to the source electrode of upper arm element 40a and the drain electrode of lower arm element 40b. U-phase line 15 is connected to U-phase coil 310.

[0026] In V-phase power card 42, a V-phase line 16 is connected to the source electrode of upper arm element 40a and the drain electrode of lower arm element 40b. V-phase line 16 is connected to V-phase coil 320.

[0027] In W-phase power card 43, a W-phase line 17 is connected to the source electrode of upper arm element 40a and the drain electrode of lower arm element 40b. W-phase line 17 is connected to W-phase coil 330.

[0028] As shown in FIGS. 2 and 4, the housing 60 has an annular side wall 60a and a bottom wall 60b continuous with the side wall 60a. The housing 60 accommodates the P wiring 10P, the N wiring 10N, the filter circuit 20, the smoothing capacitor 30, the transformer circuit 40, and the circuit board 50. The housing 60 is configured so that a portion of each of the phase lines 15 to 17 is exposed to the outside of the housing 60. The housing 60 is primarily made of a metal such as aluminum. In FIGS. 2 and 4, the housing 60 is simplified to avoid cluttering the drawings.

[0029] <Filter circuit> 2 to 5, the filter circuit 20 will be described. As shown in Fig. 2, Fig. 5, etc., the filter circuit 20 includes one core 23, one P-side coil 21, and one N-side coil 22. The filter circuit 20 also includes Y capacitors 24 and 25. The Y capacitors 24 and 25 correspond to capacitors.

[0030] Note that Fig. 2 shows a simplified illustration of the filter circuit 20. Fig. 3 shows an example of the filter circuit 20. Fig. 4 shows an example of the positional relationship between the core 23 and the Y capacitors 24 and 25 as viewed from the direction of arrow IV in Fig. 2.

[0031] As shown in Fig. 4 and other figures, core 23 is an annular member equipped with a magnetic body. Core 23 is, for example, an annular magnetic body sealed with resin. Core 23 is mounted on bottom wall 60b of housing 60. Core 23 has mounting surface 23a in contact with bottom wall 60b, top surface 23b opposite mounting surface 23a, and side surfaces 23c and 23d continuing to mounting surface 23a and top surface 23b. Bottom wall 60b corresponds to the mounting portion.

[0032] Core 23 has a height corresponding to the distance between mounting surface 23a and top surface 23b. Core 23 also has a width corresponding to the distance between side surface 23c and side surface 23d. Mounting surface 23a and top surface 23b are arranged parallel to the XY plane. Side surfaces 23c and 23d are arranged parallel to the YZ plane. The XY plane is a plane defined by the X-axis and Y-axis. The YZ plane is a plane defined by the Y-axis and Z-axis.

[0033] Note that Z1 indicates an imaginary plane along the mounting surface 23a, Z2 indicates an imaginary plane along the top surface 23b, X1 indicates an imaginary plane along the side surface 23c, and X2 indicates an imaginary plane along the side surface 23d.

[0034] 5 and other figures, the P-side coil 21 includes a first coil portion 21a and a second coil portion 21b provided continuously with the first coil portion 21a. The first coil portion 21a and the second coil portion 21b are wound around a core 23.

[0035] P-side coil 21 is made of a conductive material. As shown in FIG. 3, P-side coil 21 can be made of, for example, a bus bar. First coil portion 21a and second coil portion 21b are connected by a bolt or the like. The location where first coil portion 21a and second coil portion 21b are connected is fastening portion 71. In this way, P-side coil 21 configures a single coil by connecting first coil portion 21a and second coil portion 21b.

[0036] As shown in FIG. 5, P-side coil 21 is connected to first P wiring portion 11 and second P wiring portion 12. First coil portion 21a is connected to first P wiring portion 11. Second coil portion 21b is connected to second P wiring portion 12. P-side coil 21 is provided between first P wiring portion 11 and second P wiring portion 12. Therefore, P-side coil 21 can be considered to be part of P wiring 10P.

[0037] A Y capacitor 24 is connected between the P-side coil 21 and the ground. One terminal of the Y capacitor 24 is connected to the P-side coil 21, and the other terminal is grounded. One terminal of the Y capacitor 24 is connected between the first coil portion 21a and the second coil portion 21b. As shown in FIG. 3, one terminal of the Y capacitor 24 is connected to the fastening portion 71. The point on the P-side coil 21 where the Y capacitor 24 is connected is the point where the first coil portion 21a and the second coil portion 21b are connected. The point on the P-side coil 21 where the Y capacitor 24 is connected can also be referred to as a capacitor connection point.

[0038] In this embodiment, as an example, a Y capacitor 24 is connected to the fastening portion 71 between the first coil portion 21a and the second coil portion 21b. However, the present disclosure is not limited to this. The P-side coil 21 may be formed by integrally forming the first coil portion 21a and the second coil portion 21b. In this case, the P-side coil 21 can be said to include the first coil portion 21a, which is located closer to the first P wiring portion 11 than the capacitor connection point, and the second coil portion 21b, which is located closer to the second P wiring portion 12 than the capacitor connection point.

[0039] 2 and 4, the other terminal of the Y capacitor 24 is connected to the bottom wall 60b (earth) via the housing connection 61. In other words, the capacitor connection point of the P-side coil 21 is connected to the earth via the Y capacitor 24. The inductance value from the Y capacitor 24 to the bottom wall 60b is preferably smaller than the inductance value of the first coil portion 21a or the second coil portion 21b. As a result, as shown by the solid line in FIG. 8, the filter circuit 20 can reduce the impedance on the high-frequency side and recover noise on the high-frequency side. Furthermore, it can be said that the power conversion device 100 can improve the overall noise suppression effect with the filter circuit 20 (LCL filter), and can particularly suppress noise on the high-frequency side. The other terminal of the Y capacitor 24 may be directly connected to the bottom wall 60b. The bottom wall 60b corresponds to the grounded portion.

[0040] 4, Y capacitor 24 is disposed adjacent to core 23. More specifically, Y capacitor 24 is disposed opposite side surface 23c of core 23. In other words, Y capacitor 24 is disposed between imaginary planes Z1 and Z2. The smaller the distance between Y capacitor 24 and core 23, the more compact the filter circuit 20 can be.

[0041] Furthermore, the Y capacitor 24 is disposed adjacent to the core 23 and is grounded to the bottom wall 60b on which the core 23 is mounted. This makes it easy to shorten the physical distance from the Y capacitor 24 to the bottom wall 60b in the filter circuit 20. This makes it easy for the filter circuit 20 to direct noise to the bottom wall 60b, making it easier to reduce high-frequency noise.

[0042] However, the positional relationship between the core 23 and the Y capacitor 24 is not limited to the above. The Y capacitor 24 may be disposed opposite the mounting surface 23a or the upper surface 23b. In other words, the Y capacitor 24 may be disposed between the imaginary planes X1 and X2.

[0043] The core 23, P-side coil 21, and Y capacitor 24 can also be considered to be a P-side filter circuit. In the P-side filter circuit, Y capacitor 24 is connected between the first coil portion 21a and the second coil portion 21b. Therefore, the P-side filter circuit can be considered to have two pseudo-cores. In other words, the P-side filter circuit can be said to constitute an LCL filter. Also, by connecting Y capacitor 24 to the center point of the turns, the P-side filter circuit can be said to obtain LCL filter characteristics.

[0044] 5 and other figures, the N-side coil 22 includes a first coil portion 22a and a second coil portion 22b provided continuously with the first coil portion 22a. The first coil portion 22a and the second coil portion 22b are wound around a core 23.

[0045] The N-side coil 22 is made of a conductive material. As shown in FIG. 3, the N-side coil 22 can be made of, for example, a bus bar. The first coil portion 22a and the second coil portion 22b are connected by a bolt or the like. The first coil portion 22a and the second coil portion 22b are connected at a fastening portion 72. In this way, the N-side coil 22 is made up of a single coil, with the first coil portion 22a and the second coil portion 22b connected to each other.

[0046] As shown in FIG. 5, the N-side coil 22 is connected to the first N wiring portion 13 and the second N wiring portion 14. The first coil portion 22a is connected to the first N wiring portion 13. The second coil portion 22b is connected to the second N wiring portion 14. The N-side coil 22 is provided between the first N wiring portion 13 and the second N wiring portion 14. Therefore, the N-side coil 22 can be considered to be part of the N wiring 10N.

[0047] A Y capacitor 25 is connected between the N-side coil 22 and the ground. One terminal of the Y capacitor 25 is connected to the N-side coil 22, and the other terminal is grounded. One terminal of the Y capacitor 25 is connected between the first coil portion 22a and the second coil portion 22b. As shown in FIG. 3, one terminal of the Y capacitor 25 is connected to the fastening portion 72. The point on the N-side coil 22 where the Y capacitor 25 is connected is the point where the first coil portion 22a and the second coil portion 22b are connected. The point on the N-side coil 22 where the Y capacitor 25 is connected can also be referred to as a capacitor connection point.

[0048] In this embodiment, as an example, the Y capacitor 24 is connected to the fastening portion 72 between the first coil portion 22a and the second coil portion 22b. However, the present disclosure is not limited to this. The N-side coil 22 may be formed by integrally forming the first coil portion 22a and the second coil portion 22b. In this case, the N-side coil 22 can be said to include the first coil portion 22a, which is located closer to the first N wiring portion 13 than the capacitor connection point, and the second coil portion 22b, which is located closer to the second N wiring portion 14 than the capacitor connection point.

[0049] 2 and 4, the other terminal of Y capacitor 25 is connected to bottom wall 60b (earth) via housing connection 62. In other words, the capacitor connection point of N-side coil 22 is connected to earth via Y capacitor 25. The inductance value from Y capacitor 25 to bottom wall 60b is preferably smaller than the inductance value of first coil portion 22a or second coil portion 22b. This allows filter circuit 20 to suppress noise on the high frequency side, as described for Y capacitor 24. The other terminal of Y capacitor 25 may also be directly connected to bottom wall 60b.

[0050] 4, Y capacitor 25 is disposed adjacent to core 23. More specifically, Y capacitor 25 is disposed opposite side surface 23d of core 23. In other words, Y capacitor 25 is disposed between imaginary planes Z1 and Z2. The smaller the distance between Y capacitor 25 and core 23, the more compact the filter circuit 20 can be.

[0051] Furthermore, the Y capacitor 25 is disposed adjacent to the core 23 and is grounded to the bottom wall portion 60b on which the core 23 is mounted. Therefore, in the filter circuit 20, noise can be easily passed to the bottom wall portion 60b, similarly to the above, and high-frequency noise can be easily reduced.

[0052] However, the positional relationship between the core 23 and the Y capacitor 25 is not limited to the above. The Y capacitor 25 may be disposed opposite the mounting surface 23a or the upper surface 23b. In other words, the Y capacitor 25 may be disposed between the imaginary planes X1 and X2.

[0053] The core 23, N-side coil 22, and Y capacitor 25 can also be considered to be an N-side filter circuit. In the N-side filter circuit, the Y capacitor 25 is connected between the first coil portion 22a and the second coil portion 22b. Therefore, the N-side filter circuit can be considered to have two pseudo-cores. In other words, the N-side filter circuit can be said to constitute an LCL filter. Also, by connecting the Y capacitor 25 to the center point of the turn, the N-side filter circuit can be said to obtain LCL filter characteristics.

[0054] In this embodiment, as an example, a filter circuit 20 including a P-side filter circuit and an N-side filter circuit is employed. Furthermore, it can be said that the filter circuit 20 has a core 23 that is common to the P-side filter circuit and the N-side filter circuit.

[0055] However, the present disclosure is not limited to this. The filter circuit 20 may be configured to include only the core 23, the P-side coil 21 as a coil, and the Y-side capacitor 24 as a capacitor. Similarly, the filter circuit 20 may be configured to include only the core 23, the N-side coil 22 as a coil, and the Y-side capacitor 25 as a capacitor. In other words, the filter circuit 20 may be configured to include at least one of a P-side filter circuit and an N-side filter circuit.

[0056] In this embodiment, an example in which bus bars are used as the P-side coil 21 and the N-side coil 22 is adopted. However, the present disclosure is not limited thereto. As shown in FIG. 6 , the filter circuit 20 may use lead wires as the P-side coil 21 and the N-side coil 22.

[0057] The Y capacitors 24 and 25 are connected to the conductors exposed from the insulators of the lead wires by soldering or the like. Connection 73 in Figure 6 is a capacitor connection point to which one terminal of the Y capacitor 24 is connected. Connection 74 is a capacitor connection point to which one terminal of the Y capacitor 25 is connected.

[0058] 7, the inductance value of the filter circuit 20 can be increased by increasing the number of turns (windings) of the P-side coil 21. Similarly, the inductance value of the filter circuit 20 can be increased by increasing the number of turns of the N-side coil 22.

[0059] 5, a Y capacitor 24 is connected to an intermediate portion of the P-side coil 21 wound around the core 23. Similarly, a Y capacitor 25 is connected to an intermediate portion of the P-side coil 21 wound around the core 23.

[0060] 7, a Y capacitor 24 is connected to a portion of the P-side coil 21 that is not wound around the core 23. Similarly, in the filter circuit 20, a Y capacitor 25 is connected to a portion of the N-side coil 22 that is not wound around the core 23. That is, the P-side coil 21 has a lead-out portion 241 for connecting the Y capacitor 24. The N-side coil 22 has a lead-out portion 251 for connecting the Y capacitor 25. Therefore, in the filter circuit 20, it is easy to connect the Y capacitors 24, 25 to the coils 21, 22.

[0061] Incidentally, the parasitic inductance (parasitic L) of the filter circuit 20 varies depending on the length from the Y capacitors 24, 25 to the bottom wall portion 60b. The length from the Y capacitors 24, 25 to the bottom wall portion 60b can also be called the equivalent series inductance (ESL).

[0062] FIG. 8 is a simulation result showing the relationship between frequency (MHz) and attenuation (dB) (attenuation frequency characteristic graph). The solid line in FIG. 8 indicates the characteristics of a configuration with a smaller parasitic inductance than the two-dot chain line. In other words, FIG. 8 can be said to show the difference in attenuation caused by filter circuits 20 with different parasitic inductances. Therefore, FIG. 8 can also be said to be a simulation result showing the relationship between the length from Y capacitors 24, 25 to bottom wall portion 60b in filter circuit 20 and the noise suppression effect of filter circuit 20.

[0063] 8, it can be seen that the noise suppression effect of the filter circuit 20 can be improved as the parasitic inductance is smaller in a specific frequency band. Furthermore, the parasitic inductance of the filter circuit 20 decreases as the length from the Y capacitors 24, 25 to the bottom wall 60b decreases. Therefore, it is preferable to configure the filter circuit 20 so that the length from the Y capacitors 24, 25 to the bottom wall 60b is minimized.

[0064] Therefore, in filter circuit 20, core 23 is disposed near housing 60 so that Y capacitors 24, 25 are close to bottom wall 60b. In addition, power conversion device 100 configures housing 60 in a shape so that Y capacitors 24, 25 are close to bottom wall 60b. Furthermore, filter circuit 20 may surround core 23 with a metal housing, and the metal housing may be electrically connected to housing 60.

[0065] Furthermore, the noise suppression effect of the filter circuit 20 differs depending on the capacitor connection point. Figure 9 is a graph showing the attenuation frequency characteristics. The two-dot chain line in Figure 9 shows the characteristics of an LC filter.

[0066] The dashed-dotted line indicates the characteristics of a configuration in which the capacitor connection point is shifted to one side. In this configuration, for example, the capacitor connection point is shifted from the center of P-side coil 21 toward first P wiring portion 11, and the inductance difference between first coil portion 21a and second coil portion 21b is about 25%.

[0067] The solid line indicates the characteristics of a configuration in which the capacitor connection point is at the center. In this configuration, for example, the capacitor connection point is provided at the center of the P-side coil 21, and the inductance values ​​of the first coil portion 21a and the second coil portion 21b are equal. Note that although the P-side coil 21 is used as an example for explanation, the same applies to the N-side coil 22.

[0068] 9 shows the difference in attenuation caused by filter circuits 20 with different capacitor connection points. Also, FIG. 9 shows the results of a simulation showing the capacitor connection points in filter circuit 20 and the noise suppression effect of filter circuit 20.

[0069] 9, the filter circuit 20 can achieve a higher noise suppression effect than an LC filter by, for example, setting the inductance difference between the first coil portion 21a and the second coil portion 21b to about 25%. That is, it is preferable that the filter circuit 20 has capacitor connection points so that the inductance difference between the first coil portion 21a and the second coil portion 21b is within 25%. In this case, the first coil portion 21a and the second coil portion 21b of the P-side coil 21 have different lengths.

[0070] The length here can also be referred to as the length of the portion of the first coil portion 21a and the second coil portion 21b wound around the core 23. The length can also be referred to as the length of the first coil portion 21a and the second coil portion 21b in the direction in which they are wound around the core 23. Furthermore, the length can also be referred to as the coil length from one end to the other end of the first coil portion 21a and the second coil portion 21b. The coil length can also be referred to as the circumferential length.

[0071] 9, the noise suppression effect of the filter circuit 20 can be further enhanced by making the inductance values ​​of the first coil portion 21a and the second coil portion 21b equal. That is, it is preferable that the filter circuit 20 has capacitor connection points so that the inductance values ​​of the first coil portion 21a and the second coil portion 21b are equal. Therefore, it is preferable that the Y capacitor 24 be connected to the center in the longitudinal direction of the P-side coil 21. The center in the longitudinal direction of the P-side coil 21 can also be said to be the center in the longitudinal direction of the portion wound around the core 23.

[0072] In the filter circuit 20, it is preferable to space the P-side coil 21 and the N-side coil 22 apart enough to ensure electrical insulation between the P-side coil 21 and the N-side coil 22. However, it is preferable to place the first coil portion 21a and the second coil portion 21b close to each other inside the core 23 in the filter circuit 20. Similarly, it is preferable to place the first coil portion 22a and the second coil portion 22b close to each other inside the core 23 in the filter circuit 20. This allows the filter circuit 20 to increase impedance due to mutual inductance in the P-side coil 21 and the N-side coil 22, thereby suppressing the intrusion of noise.

[0073] On the other hand, in filter circuit 20, it is preferable that the spacing between first coil portion 21a and second coil portion 21b be wide outside core 23. Similarly, it is preferable that the spacing between first coil portion 22a and second coil portion 22b be wide outside core 23. This allows filter circuit 20 to reduce stray capacitance.

[0074] Furthermore, filter circuit 20 can improve the noise suppression effect compared to a configuration (comparison example filter circuit) that uses two cores of the same size as core 23. This point will be explained using Figures 10 to 13. Here, the explanation will be made while comparing filter circuit 20 with the comparison example filter circuit.

[0075] FIG. 10 shows a filter circuit 20. As described above, the filter circuit 20 has a first coil portion 21a and a second coil portion 21b, and a first coil portion 22a and a second coil portion 22b, provided for one core 23. In other words, the filter circuit 20 has coils 21 and 22, each with two turns on the P side and two turns on the N side, provided for one core 23. The filter circuit 20 also has a Y capacitor 24 and a Y capacitor 25. The filter circuit 20 has a coil wound around the core 23 with four turns. In FIG. 10, the number of turns is increased to make it easier to see that the coils are wound.

[0076] On the other hand, Figure 12 shows a comparative filter circuit. The comparative filter circuit includes two cores 231 and 232, P-side coils 211a and 211b, N-side coils 221a and 221b, and Y capacitors 24 and 25. The cores 231 and 232 are made of the same material as the core 23 and have the same size as the core 23. Therefore, the comparative filter circuit is larger in size than the filter circuit. Note that the comparative filter circuit has two turns of coil wound around each of the cores 231 and 232. In Figure 12, the number of turns has been increased to make it easier to see that the coils are wound.

[0077] The core 231 is wound with the P-side first coil portion 211a and the N-side first coil portion 221a. The core 232 is wound with the P-side second coil portion 211b and the N-side second coil portion 221b. The first coil portion 211a and the P-side second coil portion 211b are connected by a connecting wire 111. The first coil portion 221a and the N-side second coil portion 221b are connected by a connecting wire 131. The connecting wire 111 is connected to the ground via a Y capacitor 24. The connecting wire 131 is connected to the ground via a Y capacitor 25.

[0078] 11 and 13 are graphs showing impedance frequency characteristics. The solid line in Fig. 11 shows the impedance characteristics of the filter circuit 20. The dashed dotted line in Fig. 11 can be said to be the impedance characteristics for one two-turn core.

[0079] The two-dot chain line in Fig. 13 shows the impedance characteristics of the comparative filter circuit. The one-dot chain line in Fig. 13 can be said to be the impedance characteristics of two core turns.

[0080] The two-dot chain lines in Figures 11 and 13 show the impedance characteristics of a reference configuration. In the reference configuration, one P-side coil and one N-side coil are wound around one core, with a Y capacitor connected to the P-side coil and a Y capacitor connected to the N-side coil. The two-dot chain lines in Figures 11 and 13 can be said to be the impedance characteristics for one turn of the core.

[0081] As shown in Fig. 13, the comparative filter circuit can have a larger inductance than the reference configuration. Similarly, as shown in Fig. 11, the filter circuit 20 can have a larger inductance than the reference configuration. However, the filter circuit 20 can have a larger inductance than the comparative filter circuit. In this way, the filter circuit 20 can have a smaller size than the comparative filter circuit, while improving the noise suppression effect.

[0082] <Effects> As described above, the filter circuit 20 includes one core 23, the first coil portion 21a and the second coil portion 21b wound around the core 23, and the Y capacitor 24 having one terminal connected between the first coil portion 21a and the second coil portion 21b. Therefore, the filter circuit 20 can be configured to include two pseudo-cores. In other words, the filter circuit 20 can be configured to include two pseudo-cores in the P wiring 10P.

[0083] Therefore, the filter circuit 20 can be made smaller than a configuration with two cores. Furthermore, the filter circuit 20 can provide a better noise suppression effect than a configuration with one core, one coil, and one capacitor. In other words, the filter circuit 20 can provide a better noise suppression effect than an LC filter. The filter circuit 20 can also provide a similar effect on the N wiring 10N side.

[0084] Moreover, the power conversion device 100 includes the filter circuit 20 whose physical size has been reduced as described above. Therefore, the physical size of the power conversion device 100 itself can also be reduced. Furthermore, the power conversion device 100 includes the filter circuit 20 whose noise suppression effect has been improved. Therefore, the power conversion device 100 can also improve its own noise suppression effect.

[0085] In particular, inverter circuits are being required to utilize SiCMOS as switching elements and to use higher carrier frequencies in order to reduce losses. However, such inverter circuits are prone to generating noise. Therefore, EMC measures are required for inverter circuits as a noise countermeasure. A common EMC measure is to install a filter circuit.

[0086] Furthermore, inverter circuits mounted on electric vehicles are required to carry large currents, which can cause significant self-heating due to current flow, which can lead to the inverter circuit's filter circuit becoming larger.

[0087] However, the filter circuit 20 can improve the noise suppression effect while reducing the size of the circuit, and is therefore suitable for incorporation into a power conversion device that requires a large current to flow.

[0088] Although the present disclosure has been described with reference to the embodiments, it is understood that the present disclosure is not limited to the embodiments or structures. The present disclosure also encompasses various modifications and modifications within the scope of equivalents. In addition, although various combinations and forms are shown in the present disclosure, other combinations and forms including only one element, more, or less than one element are also within the scope and spirit of the present disclosure.

[0089] (Disclosure of technical ideas) This specification discloses multiple technical ideas described in the following multiple clauses. Some clauses may be written in a multiple dependent form, with the subsequent clause referring to the preceding clause as an alternative. Furthermore, some clauses may be written in a multiple dependent form, referring to another multiple dependent clause. These multiple dependent clauses define multiple technical ideas.

[0090] (Technical thought 1) One core (23) and a first coil portion (21a; 22a) wound around the core; a second coil portion (21b; 22b) provided continuously with the first coil portion and wound around the core; a capacitor (24; 25) having one terminal connected between the first coil portion and the second coil portion and the other terminal grounded;

[0091] (Technical thought 2) The filter circuit according to Technical Idea 1, wherein the first coil section and the second coil section have an inductance difference of 25% or less.

[0092] (Technical Thought 3) The filter circuit according to Technical Idea 1, wherein the first coil portion and the second coil portion have the same inductance value.

[0093] (Technical Thought 4) The filter circuit according to any one of Technical Ideas 1 to 3, wherein the inductance value from the capacitor to the grounded portion is smaller than the inductance value of the first coil portion or the second coil portion.

[0094] (Technical Thought 5) The core is mounted in a housing (60), The filter circuit according to any one of Technical Ideas 1 to 4, wherein the capacitor is disposed adjacent to the core and is grounded to a portion of the housing on which the core is mounted.

[0095] (Technical Thought 6) A power conversion device connectable to a power source (200) and an external device (300), A low-potential power line (10N), High-potential power line (10P), a transformer circuit (40) connected to the low-potential side power line and the high-potential side power line; a filter circuit (20) provided between the power supply and the transformer circuit; The filter circuit comprises: One core (23) and a first coil portion (21a; 22a) connected to at least one of the low-potential side power line and the high-potential side power line and wound around the core; a second coil portion (21b; 22b) provided continuously with the first coil portion and wound around the core; a capacitor (24; 25) having one terminal connected between the first coil portion and the second coil portion and the other terminal grounded;

[0096] (Technical Thought 7) The power conversion device according to Technical Concept 6, wherein the first coil portion and the second coil portion have an inductance difference of 25% or less.

[0097] (Technical Thought 8) The power conversion device according to Technical Idea 6, wherein the first coil portion and the second coil portion have the same inductance value.

[0098] (Technical Thought 9) The power conversion device according to any one of Technical Ideas 6 to 8, wherein the inductance value from the capacitor to the grounded portion is smaller than the inductance value of the first coil portion or the second coil portion.

[0099] (Technical Thought 10) The core is mounted in a housing (60), The power conversion device according to any one of Technical Ideas 6 to 9, wherein the capacitor is disposed adjacent to the core and is grounded to a portion of the housing on which the core is mounted. [Explanation of symbols]

[0100] 10P...P wiring, 10N...N wiring, 20...filter circuit, 21...P side coil, 21a...first coil portion, 21b...second coil portion, 22...N side coil, 22a...first coil portion, 22b...second coil portion, 24...Y capacitor, 25...Y capacitor, 40...transformer circuit, 60...casing, 100...power conversion device, 200...power supply, 300...motor

Claims

1. One core (23), a first coil portion (21a; 22a) wound around the core; a second coil portion (21b; 22b) provided continuously with the first coil portion and wound around the core; a capacitor (24; 25) having one terminal connected between the first coil portion and the second coil portion and the other terminal grounded;

2. 2. The filter circuit according to claim 1, wherein the first coil portion and the second coil portion have an inductance difference of 25% or less.

3. The filter circuit according to claim 1 , wherein the first coil portion and the second coil portion have the same inductance value.

4. 4. The filter circuit according to claim 1, wherein an inductance value from the capacitor to the grounded portion is smaller than an inductance value of the first coil portion or the second coil portion.

5. The core is mounted in a housing (60); 4. The filter circuit according to claim 1, wherein the capacitor is disposed adjacent to the core and is grounded to a portion of the housing where the core is mounted.

6. A power conversion device connectable to a power source (200) and an external device (300), A low potential side power supply line (10N), A high-potential power line (10P), a transformer circuit (40) connected to the low-potential side power line and the high-potential side power line; a filter circuit (20) provided between the power supply and the transformer circuit; The filter circuit comprises: One core (23), a first coil portion (21a; 22a) connected to at least one of the low-potential side power supply line and the high-potential side power supply line and wound around the core; a second coil portion (21b; 22b) provided continuously with the first coil portion and wound around the core; a capacitor (24; 25) having one terminal connected between the first coil portion and the second coil portion and the other terminal grounded.

7. The power conversion device according to claim 6 , wherein the first coil portion and the second coil portion have an inductance difference of 25% or less.

8. The power conversion device according to claim 6 , wherein the first coil portion and the second coil portion have the same inductance value.

9. The power conversion device according to any one of claims 6 to 8, wherein an inductance value from the capacitor to the grounded portion is smaller than an inductance value of the first coil portion or the second coil portion.

10. The core is mounted in a housing (60); 9. The power conversion device according to claim 6, wherein the capacitor is disposed adjacent to the core and is grounded to a portion of the housing where the core is mounted.

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