JP2019004363A - AC filter - Google Patents

Abstract

To reduce flux leakage from a coil.SOLUTION: An AC filter 20 includes a case 50, a substrate 51, a plurality of connectors 60, a shield member 70, a relay substrate 81, and common choke coils 21, 22. The plurality of connectors 60 are provided on the substrate 51. The common choke coils 21, 22 are connected with the substrate 51 through the connectors 60. The shield member 70 includes: bottom parts 73, each of which is disposed between a facing portion 24 of the common choke coils 21, 22 and the substrate 51; and cover parts 74, each of which extends from the bottom part 73 in a cylindrical shape along the common choke coils 21, 22. The bottom part 73 includes an insertion hole 75 into which a connection portion 82 is inserted.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an AC filter.

  A power conversion device that converts AC power into DC power by a switching operation of the switching element includes a switching element. Due to the switching operation of the switching element, conduction noise is generated in the power converter. Conducted noise needs to be reduced to a level defined by a standard (eg, CISPR). For this reason, the power conversion device includes an AC filter for reducing conduction noise.

  When the AC filter includes a plurality of coils, the characteristics (attenuation characteristics) of the AC filter may not be obtained as designed. When the characteristics of the AC filter cannot be obtained as designed, it is necessary to set constants such as a coil and a capacitor while confirming with an actual machine (actual power converter).

  One reason why the characteristics (attenuation characteristics) of the AC filter cannot be obtained as designed is that the leakage flux of each coil affects each coil. Leakage magnetic flux can be reduced by covering the coil with a shield member. For example, Patent Document 1 discloses an apparatus in which a coil is covered with a shield member.

Japanese Patent Laying-Open No. 2015-53298

By the way, it is desired to further reduce the leakage magnetic flux from the coil by improving the shielding performance by the shield member.
The objective of this invention is providing the AC filter which can reduce the leakage magnetic flux from a coil.

  An AC filter that solves the above problems includes a case, a substrate housed in the case, a plurality of connectors provided on the substrate, a plurality of coils connected to the substrate via the connector, and the coil An AC filter comprising: a shield member that reduces a leakage magnetic flux of the coil, wherein the shield member includes a portion facing the substrate of the coil, a bottom portion interposed between the connectors, and the coil from the bottom portion. And a covering portion that covers the coil, and the bottom portion includes an insertion hole through which a connection site for connecting the coil to the connector is inserted.

  According to this, a part (bottom part) of the shield member can be interposed between the portion of the coil facing the substrate and the connector. Since the covering portion of the shield member is connected to the bottom portion, a gap is hardly generated between the covering portion and the connector. Therefore, the leakage flux of the coil can be reduced. In addition, since the coil can be connected to the substrate through the connection portion inserted through the insertion hole, the coil and the substrate can be connected even if a bottom portion is provided.

  In the AC filter, the connection part may be a part of a relay board provided so as to be perpendicular to the board, and the coil may be mounted on one surface of the relay board.

  According to this, the support of the coil is stabilized.

  According to the present invention, leakage magnetic flux from a coil can be reduced.

The circuit diagram of the power converter in an embodiment. Sectional drawing which shows a part of AC filter in embodiment. The perspective view of the common choke coil in an embodiment. The perspective view of the shield member in an embodiment. The perspective view of the connector in an embodiment. Sectional drawing which shows the shield member which is not provided with a bottom part. (A) And (b) is a figure which shows the modification of the attachment aspect with respect to the relay board | substrate of a common choke coil. (A) And (b) is a figure which shows the modification of the attachment aspect with respect to the relay board | substrate of a common choke coil.

Hereinafter, an embodiment of the AC filter will be described. The AC filter of this embodiment is used as a part of a power conversion device mounted on a vehicle.
As shown in FIG. 1, the vehicle includes a power conversion device 10 and a battery B. The vehicle is an electric vehicle using an electric motor as a drive source or a hybrid vehicle. The battery B is a chargeable / dischargeable power storage device and is used as a power source of an electric motor mounted on a vehicle.

  The power conversion device 10 includes an input end 12 to which an AC power supply 11 is connected. The AC power supply 11 is a system power supply used in a general home. Although not shown, the AC power supply 11 is connected to the input terminal 12 using a home charging facility installed in the home. The power conversion device 10 is used as an in-vehicle charger that charges the battery B by converting AC power input from the AC power source 11 into DC power and outputting the DC power.

  As shown in FIG. 1, the power conversion device 10 includes an AC filter (AC filter) 20, a PFC (power factor correction circuit) 25, a DC / DC converter 30, and a DC filter (DC filter) 40. .

  The AC filter 20 is provided between the AC power supply 11 connected to the input terminal 12 and the PFC 25, and removes noise from the AC power input from the AC power supply 11. In addition, the AC filter 20 suppresses noise flowing into the AC power supply 11 by reducing noise generated in the power conversion device 10.

  The AC filter 20 includes three X capacitors (across the line capacitors) CX, two common choke coils 21 and 22 as coils, and four Y capacitors (line bypass capacitors) CY1. The AC filter 20 is a two-stage filter including two common choke coils 21 and 22.

  As shown in FIGS. 2 and 3, each of the common choke coils 21 and 22 includes two windings L1 and L2 wound around a single core 23, respectively. The winding directions of both windings L1, L2 are opposite to each other.

  As shown in FIG. 1, the windings L1 of the two common choke coils 21 and 22 are connected in series, and the windings L2 are connected in series. The X capacitor CX is provided between the input terminal 12 and the common choke coil 21, between the common choke coils 21 and 22, and between the common choke coil 22 and the PFC 25, respectively.

  The two Y capacitors CY1 are connected in series to form a series circuit of the Y capacitors CY1. By providing two series circuits of Y capacitors CY1, the AC filter 20 includes a total of four Y capacitors CY1. The series circuit of the Y capacitor CY1 is provided between the common choke coils 21 and 22 and between the common choke coils 21 and 22 and the PFC 25, respectively. The X capacitor CX and the series circuit of the Y capacitor CY1 are connected in parallel. The midpoint between the Y capacitors CY1 connected in series is grounded (grounded) to the vehicle body.

  In the AC filter 20 described above, common mode noise is reduced by the windings L1 and L2 and the Y capacitor CY1, and normal mode noise is reduced by the leakage inductance of the common choke coils 21 and 22 and the X capacitor CX.

  The PFC 25 is provided between the AC filter 20 and the DC / DC converter 30, converts an AC voltage into a DC voltage and outputs the DC voltage to the DC / DC converter 30 while improving the power factor. The PFC 25 includes switching elements Q1 and Q2 connected in series with each other, diodes D1 and D2 connected in series with each other, a PFC coil L3, and a smoothing capacitor C1. The PFC 25 described above supplies a DC voltage to the DC / DC converter 30 when the switching elements Q1 and Q2 are switched (ON / OFF operation) by a control device (not shown).

  The DC / DC converter 30 is an insulated DC / DC converter provided between the PFC 25 and the DC filter 40. The DC / DC converter 30 includes a transformer 32, a bridge circuit 31 in which four switching elements Q3, Q4, Q5, and Q6 are bridge-connected, two diodes D3 and D4 connected in series with each other, a converter coil L4, Is provided. The DC / DC converter 30 includes a rectifier circuit 35 in which four diodes D5, D6, D7, and D8 are bridge-connected, a smoothing capacitor C2, and a converter coil L5.

  In the DC / DC converter 30 described above, the switching elements Q3, Q4, Q5, and Q6 are switched by a control device (not shown). As a result, the DC voltage is converted into a DC voltage having a different voltage according to the state of charge of the battery B (voltage conversion is performed).

  In this embodiment, MOSFETs are used as the switching elements Q1, Q2, Q3, Q4, Q5, and Q6. However, IGBTs (insulated gate bipolar transistors) or the like may be used.

  The DC filter 40 includes one common choke coil 41 and four Y capacitors CY2. The common choke coil 41 has the same configuration as the common choke coils 21 and 22 described above, and includes two windings L6 and L7. The two Y capacitors CY2 are connected in series to form a series circuit of Y capacitors CY2. By providing two series circuits of Y capacitors CY2, the DC filter 40 includes a total of four Y capacitors CY2. The midpoint between the Y capacitors CY2 connected in series is grounded (grounded) to the vehicle body. The DC filter 40 reduces noise included in the DC voltage.

Next, the mounting mode of the common choke coils 21 and 22 used in the AC filter 20 will be described in detail.
As shown in FIG. 2, the AC filter 20 includes a metal case 50, a substrate 51, a connector 60, a shield member 70, and a relay substrate 81.

The case 50 is grounded (grounded) to the vehicle body. The case 50 accommodates a substrate 51, a connector 60, a shield member 70, and a relay substrate 81.
A plurality of connectors 60 are provided on the substrate 51. The substrate 51 is also provided with members (for example, an X capacitor CX and a Y capacitor CY1) 52 that constitute the AC filter 20. In addition, although illustration is abbreviate | omitted, the board | substrate 51 is provided with the other member which comprises the power converter device 10. FIG.

  The connector 60 is provided in accordance with the number of common choke coils 21 and 22 constituting the AC filter 20, and two connectors 60 are provided in the present embodiment. The connector 60 is a member for electrically connecting the common choke coils 21 and 22 to the substrate 51. The connector 60 includes an insertion port 62 that opens in an upper surface 61 that is a surface opposite to the surface facing the substrate 51. The insertion opening 62 opens in the thickness direction of the substrate 51.

  As shown in FIGS. 2 and 4, the shield member 70 is made of metal. The shield member 70 includes a flat base portion 71 and a coil housing portion 72 that is recessed from the base portion 71. The coil accommodating part 72 is provided according to the number of the common choke coils 21 and 22, and two are provided in this embodiment. The coil housing portion 72 has a bottomed cylindrical shape and opens in the base portion 71. The coil housing portion 72 includes a rectangular bottom portion 73 and a cylindrical (frame-shaped) covering portion 74 that connects the bottom portion 73 and the base portion 71. The dimension of the covering part 74 between the bottom part 73 and the base part 71 (the dimension of the covering part 74 in the axial direction) is larger than the outer diameter of the core 23. The bottom portion 73 includes an insertion hole 75 that allows the inside and outside of the coil housing portion 72 to communicate with each other.

  As shown in FIGS. 2 and 5, the shield member 70 is fixed to the case 50. Each bottom portion 73 of the shield member 70 is disposed so as to overlap the upper surface 61 of each connector 60, and the covering portion 74 is disposed so as to extend from the connector 60 in the thickness direction of the substrate 51. The insertion hole 75 and the insertion port 62 overlap each other.

  As shown in FIGS. 2 and 3, common choke coils 21 and 22 are provided on the relay substrate 81. Specifically, the common choke coils 21 and 22 are mounted on one surface of the relay substrate 81. Both ends of the windings L1, L2 of the common choke coils 21, 22 are connected to the relay substrate 81. Thereby, winding L1, L2 and the relay board | substrate 81 are electrically connected. In the present embodiment, the common choke coils 21 and 22 are provided on the relay substrate 81 so that the axis (center axis) of the core 23 intersects the relay substrate 81 perpendicularly. One end of the relay substrate 81 serves as a connection part 82 connected to the connector 60. Although illustration is omitted, the wiring (conductor pattern) in which both ends of the windings L1 and L2 are connected extends to the connection part 82.

  The relay board 81 and the common choke coils 21 and 22 attached to the relay board 81 are housed in the coil housing portion 72. The relay substrate 81 is inserted into the coil housing portion 72 so as to be perpendicular to the substrate 51, that is, so that the thickness direction of the relay substrate 81 and the thickness direction of the substrate 51 are orthogonal to each other.

  The connection part 82 of the relay substrate 81 is inserted into the insertion port 62 through the insertion hole 75. Thereby, the common choke coils 21 and 22 and the substrate 51 are electrically connected via the relay substrate 81 and the connector 60. More specifically, the wiring (conductor pattern) of the relay board 81 and the wiring (conductor pattern) of the board 51 are electrically connected by a conductor provided in the connector 60. The common choke coils 21 and 22 are arranged such that a part of the core 23 in the radial direction (a direction orthogonal to the axis of the core 23) faces the substrate 51 (the upper surface 61 of the connector 60) via the bottom 73. Therefore, a part of the common choke coils 21 and 22 in the radial direction of the core 23 becomes the facing portion 24.

  A bottom 73 of the shield member 70 is interposed between the facing portion 24 and the substrate 51. That is, it can be considered that a part of the shield member 70 is folded between the coil and the substrate 51. Thus, the facing portion 24 is covered with the bottom 73 from the thickness direction of the substrate 51. Further, the covering portion 74 is arranged so as to extend from the bottom portion 73 along the common choke coils 21 and 22 in a cylindrical shape. That is, the covering portion 74 extends so as to surround the common choke coils 21 and 22. As a result, the common choke coils 21 and 22 are covered with the covering portion 74 from a direction orthogonal to the thickness direction of the substrate 51 (a direction along the substrate 51).

Next, the operation of the AC filter 20 of this embodiment will be described.
When the battery B is charged by the power conversion device 10, a magnetic flux is generated by a current flowing through the windings L1, L2 of the common choke coils 21, 22. Leakage magnetic flux from the common choke coils 21 and 22 is reduced by the shield member 70.

  As shown in FIG. 6, if the common choke coils 21 and 22 are connected to the substrate 51 by soldering, the shield member 70 is attached after the windings L1 and L2 of the common choke coils 21 and 22 are soldered to the substrate 51. Will be provided. In this case, the shield member 70 cannot be provided between the common choke coils 21 and 22, the portion facing the substrate 51, and the substrate 51. That is, the shield member 70 includes only the covering portion 74. Then, a gap is easily formed between the substrate 51 and the shield member 70 (the covering portion 74 in the embodiment) (P1 in the figure), and the magnetic flux easily leaks from this gap.

  On the other hand, when the common choke coils 21 and 22 and the substrate 51 are electrically connected using the connector 60, it is not necessary to perform soldering. Therefore, the upper surface 61 of the connector 60 is covered by the shield member 70. Later, the common choke coils 21 and 22 can be attached to the substrate 51. As a result, when the relay substrate 81 is inserted into the connector 60, the bottom 73 is interposed between the facing portion 24 and the upper surface 61 of the connector 60, and the facing portion 24 is covered by the bottom 73 from the thickness direction of the substrate 51. It will be. As a result, the bottom 73 of the shield member 70 connected to the covering portion 74 is folded between the facing portion 24 and the connector 60, and a gap is generated between the upper surface 61 of the connector 60 and the covering portion 74. It is suppressed.

Therefore, according to the above embodiment, the following effects can be obtained.
(1) The shield member 70 includes a bottom portion 73 and a covering portion 74. Since the bottom portion 73 is interposed between the connector 60 and the facing portion 24, the leakage magnetic flux is reduced as compared with the case where the shield member 70 is not interposed between the connector 60 and the facing portion 24. Accordingly, the two common choke coils 21 and 22 are not easily affected by the leakage magnetic flux of each other, and the designed (ideal) characteristics of the AC filter 20 are easily obtained.

  (2) By connecting the common choke coils 21 and 22 to the substrate 51 by the connector 60, the common choke coils 21 and 22 are separated from the substrate 51 by the amount of the connector 60. Therefore, as compared with the case where the common choke coils 21 and 22 are directly provided on the substrate 51, the insulation distance (creeping distance) between the member 52 provided on the substrate 51 and the common choke coils 21 and 22 is ensured by the connector 60 minutes. It can be said that. Accordingly, the member 52 provided on the substrate 51 can be disposed close to the common choke coils 21 and 22 in a direction along the surface of the substrate 51 (a direction orthogonal to the thickness direction of the substrate 51). For example, as shown by a two-dot chain line in FIG. 2, when the common choke coils 21 and 22 are provided directly on the substrate 51, it is necessary to separate the member 52 from the common choke coils 21 and 22 in order to secure an insulation distance. is there. On the other hand, when the connector 60 is provided, the member 52 can be brought closer to the connector 60 (common choke coils 21 and 22) by the insulation distance secured by the connector 60. As a result, the AC filter 20 can be downsized, and thus the power converter 10 can be downsized.

(3) The common choke coils 21 and 22 are mounted on one side of the relay substrate 81. Thereby, the support of the common choke coils 21 and 22 can be stabilized.
In addition, you may change embodiment as follows.

  As shown in FIG. 7A and FIG. 7B, the common choke coils 21 and 22 are such that the axis of the core 23 and the relay board 81 are parallel, and the axis direction of the core 23 and the board 51 May be arranged so that their thickness directions are the same. In this case, the facing portion 24 is an end portion on the connection portion 82 side of both ends of the core 23 in the axial direction, and this end portion is covered with the bottom portion 73 of the shield member 70. Further, in the common choke coils 21 and 22, the radial portion of the core 23 is covered with the covering portion 74 over the entire circumference. As described above, the facing portion 24 can be in a different position depending on how the common choke coils 21 and 22 are attached.

  As shown in FIGS. 8A and 8B, the common choke coils 21 and 22 have the axis of the core 23 parallel to the relay board 81, and the axis of the core 23 and the board 51 You may arrange | position so that a thickness direction may orthogonally cross.

  A part of the facing portion 24 may face the substrate 51 without using the connector 60. In this case, the bottom 73 may be interposed only between the portion of the facing portion 24 that faces the substrate 51 without using the connector 60 and the substrate 51.

  -The connection part may be provided in the connector 60. Specifically, the connector 60 includes a connection portion that protrudes from the upper surface 61 instead of the insertion port 62. And the coil side connector provided with the insertion port into which this connection site | part is inserted is provided in the relay board | substrate 81. FIG. The connecting portion is inserted through the insertion hole 75 and enters the coil housing portion 72, and is connected to the coil-side connector provided on the relay substrate 81. That is, the fitting relationship between the common choke coils 21 and 22 and the connector 60 may be opposite to that of the embodiment.

The shape of the core 23 may be changed as appropriate. For example, the core 23 may be a square ring.
In place of the relay substrate 81, a coil-side connector that can be inserted into the insertion port 62 of the connector 60 provided on the substrate 51 may be used.

A coil other than the common choke coils 21 and 22 may be used as the coil. For example, as a coil, you may use what wound one coil | winding to the core.
The AC filter 20 may be a multi-stage filter, and may be a three-stage filter or more. That is, it is only necessary to provide a plurality of common choke coils (coils) constituting the filter.

  The AC filter 20 may be used in any power conversion device as long as it is a power conversion device connected to an AC power supply.

  DESCRIPTION OF SYMBOLS 20 ... AC filter, 21, 22 ... Common choke coil (coil), 24 ... Opposite part, 50 ... Case, 51 ... Substrate, 60 ... Connector, 70 ... Shield member, 73 ... Bottom part, 74 ... Covering part, 75 ... Insertion Hole, 82 ... connection site.

Claims (2)

Case and
A substrate housed in the case;
A plurality of connectors provided on the substrate;
A plurality of coils connected to the substrate via the connector;
An AC filter comprising a shield member for reducing leakage flux of the coil,
The shield member is
A portion of the coil facing the substrate, and a bottom portion interposed between the substrate,
A cylindrical portion extending from the bottom along the coil and covering the coil,
The bottom part is an AC filter provided with an insertion hole through which a connection site for connecting the coil to the connector is inserted. The connection part is a part of a relay board provided to be perpendicular to the board,
The AC filter according to claim 1, wherein the coil is mounted on one side of the relay substrate.