JP2017188681A - On-vehicle power conversion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an on-vehicle power conversion device capable of suitably reducing the common mode noise and normal mode noise contained in DC power.SOLUTION: An on-vehicle inverter device 30 comprises a power module 42 which converts DC power into AC power, and a noise reducing unit 50 provided on an input side of the power module 42 and reducing the common mode noise and normal mode noise contained in the DC power. The noise reducing unit 50 comprises a common mode choke coil 51 including a core and a first winding 53a and a second winding 53b wound around the core, and a smoothing capacitor 73 constituting a low-pass filter circuit 74 in cooperation with the common mode choke coil 51. The on-vehicle inverter device 30 comprises a damping unit which generates eddy current by a leakage flux generated from the common mode choke coil 51.SELECTED DRAWING: Figure 5

Description

  The present invention relates to an in-vehicle power converter.

  2. Description of the Related Art Conventionally, an in-vehicle power conversion device that performs DC power conversion is known (see, for example, Patent Document 1). The on-vehicle power conversion device is used to drive an electric motor mounted on a vehicle, as shown in Patent Document 1, for example.

Japanese Patent Laid-Open No. 2015-033143

  Here, both common mode noise and normal mode noise can be mixed in the DC power to be converted by the in-vehicle power converter. In this case, the case where the power conversion by the vehicle-mounted power conversion device is not normally performed due to these noises may occur. In particular, the frequency of normal mode noise varies depending on the type of vehicle on which the in-vehicle power conversion device is mounted. For this reason, from the viewpoint of versatility that can be applied to a large number of vehicle types, it is required that normal mode noise in a wide frequency band can be reduced. However, in terms of being mounted on a vehicle, it is not preferable to increase the size of the on-vehicle power converter.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to provide an in-vehicle power conversion device that can suitably reduce common mode noise and normal mode noise included in DC power.

  An in-vehicle power conversion device that achieves the above object includes a power conversion circuit that performs DC power conversion, and a common mode noise and a normal mode noise included in the DC power provided on the input side of the power conversion circuit. A noise reduction unit for reducing the noise reduction unit, wherein the noise reduction unit is wound around the core, the first winding wound around the first winding part of the core, and the second winding part of the core A common mode choke coil having a second winding; and a smoothing capacitor that forms a low-pass filter circuit in cooperation with the common mode choke coil. The noise reduction unit reduces common mode noise and normal mode noise. DC power is input to the power conversion circuit, and eddy currents are generated by leakage magnetic flux generated from the common mode choke coil. A damping unit that lowers a Q value of the low-pass filter circuit, and the damping unit configures a magnetic path through which the leakage magnetic flux flows, thereby increasing a leakage inductance of the common mode choke coil. And

  According to this configuration, common mode noise included in the DC power to be converted is reduced by the common mode choke coil. Further, the common mode choke coil generates a leakage magnetic flux when a normal mode current flows. Thereby, normal mode noise can be reduced using the low-pass filter circuit comprised by the common mode choke coil and the smoothing capacitor. Therefore, since a dedicated coil for reducing normal mode noise can be omitted, it is possible to suppress an increase in the size of the in-vehicle power converter.

  Further, since the Q value of the low-pass filter circuit is lowered by the damping unit, it is possible to reduce normal mode noise having a frequency close to the resonance frequency of the low-pass filter circuit by using the noise reduction unit. As a result, the frequency band of normal mode noise that can be reduced by the noise reduction unit is widened, so that versatility can be improved. Further, since the damping unit is configured to generate an eddy current by the leakage magnetic flux, the flowing current is lower than that of a damping resistor or the like connected in series to the common mode choke coil, and it is difficult to generate heat. Thereby, compared with the structure which uses a damping resistor etc., size reduction of a vehicle-mounted power converter device is easy. Therefore, it is possible to improve versatility while achieving both the suppression of the increase in size of the in-vehicle power conversion device and the reduction of both common mode noise and normal mode noise.

  In particular, according to this configuration, the leakage inductance of the common mode choke coil is increased because the damping portion forms a magnetic path through which the leakage magnetic flux flows. Thereby, the resonance frequency of the low-pass filter circuit can be lowered. Therefore, the gain for normal mode noise in a frequency band higher than the resonance frequency is likely to be small as compared with a configuration without a damping unit. Therefore, normal mode noise in a frequency band higher than the resonance frequency can be further reduced.

About the said vehicle-mounted power converter device, the said damping part is good to cover at least one part of the side surface of the said common mode choke coil.
According to such a configuration, the damping part covers at least a part of the side surface of the common mode choke coil, whereby the Q value of the low-pass filter circuit is lowered and the leakage inductance is increased. Thereby, the above-described effect can be obtained with a relatively simple configuration.

  The vehicle-mounted power conversion device includes a circuit board on which a wiring pattern is formed, and a case in which the power conversion circuit, the circuit board, and the noise reduction unit are housed, and the damping unit includes the case It is good to be comprised with the material whose relative permeability is higher than.

  According to such a configuration, the leakage magnetic flux is more easily guided to the damping part than the case. Thereby, it can suppress that a leakage magnetic flux diverges toward a case, and can raise the leakage inductance of a common mode choke coil.

About the said vehicle-mounted power converter device, the said damping part is good to be comprised with the material whose electrical resistivity is higher than the said case.
According to such a configuration, since the resistance value of the damping part can be made higher than the resistance value of the case, the damping effect by the damping part can be further enhanced. Thereby, the Q value of the low-pass filter circuit can be further lowered.

  In the on-vehicle power conversion device, the damping part has a bottomed box shape having an opening covered by the case, and the common mode choke coil is an accommodation space defined by the damping part and the case. It is good to be housed.

  According to such a configuration, the surface other than the surface on the opening side of the common mode choke coil can be covered with the damping portion. As a result, the Q value of the low-pass filter circuit can be lowered while increasing the leakage inductance more suitably. Moreover, the heat of the damping part produced by the eddy current can be transmitted to the case.

About the said vehicle-mounted power converter device, the said damping part is good to consist of a conductive metal film for shielding which coat | covers at least one part of the said common mode choke coil.
The on-vehicle power converter includes a circuit board on which a wiring pattern is formed, and the damping part is a conductive shield for fixing to the circuit board in a state in which the common mode choke coil is accommodated from one open surface. It is good to consist of a conductive metal case and the conductive metal film for shielding formed in the area | region inside the opening part of the said conductive metal case for shielding in the said circuit board.

  According to the present invention, common mode noise and normal mode noise included in DC power can be suitably reduced.

The partially broken figure which shows typically the outline | summary of the vehicle-mounted inverter apparatus in 1st Embodiment. The disassembled perspective view which shows the structure of a noise reduction part typically. Sectional drawing which shows the structure of a noise reduction part typically. The partially broken figure of a common mode choke coil. The equivalent circuit diagram which shows the electric constitution of the inverter apparatus for vehicle mounting. The circuit diagram which shows the electrical constitution of the inverter apparatus for vehicle mounting. The graph which shows the frequency characteristic of the low-pass filter circuit with respect to normal mode noise. The front view which shows typically the common mode choke coil of another example. Sectional drawing which shows the damping part of another example typically. Sectional drawing which shows the damping part of another example typically. The disassembled perspective view which shows typically the structure of the noise reduction part in 2nd Embodiment. Sectional drawing which shows the structure of a noise reduction part typically. The partially broken figure of a common mode choke coil and a damping part. The disassembled perspective view which shows typically the structure of the noise reduction part in 3rd Embodiment. Sectional drawing which shows the structure of a noise reduction part typically.

(First embodiment)
Hereinafter, an embodiment of an in-vehicle inverter device as an in-vehicle power conversion device will be described.

  As shown in FIG. 1, the in-vehicle inverter device 30 is provided in contact with the heat sink 10. The heat sink 10 is grounded to the vehicle body. The in-vehicle inverter device 30 drives the electric motor 20 mounted on the vehicle.

  The electric motor 20 includes a rotor 21, a stator 22, and a coil 23 wound around the stator 22. When the coil 23 is energized, the rotor 21 rotates and the electric motor 20 is driven. The drive current of the electric motor 20 is higher than the signal current or the like, and is, for example, 10 A or more, preferably 20 A or more.

  The in-vehicle inverter device 30 includes an inverter case 31 in which various components such as a circuit board 41, a power module 42, and a noise reduction unit 50 are accommodated. The inverter case 31 is made of a nonmagnetic conductive material (for example, a metal such as aluminum) having heat conductivity. As the nonmagnetic material in the present embodiment, for example, a material having a relative permeability lower than “3” can be considered. The inverter case 31 corresponds to a “case”.

  The inverter case 31 includes a plate-like base member 32 that is in contact with the heat sink 10, and a bottomed cylindrical cover member 33 that is assembled to the base member 32. The base member 32 and the cover member 33 are fixed to the heat sink 10 by a bolt 34 as a fixing tool.

  Incidentally, since the inverter case 31 and the heat sink 10 are in contact with each other, they are thermally coupled. The in-vehicle inverter device 30 is disposed at a position where it is thermally coupled to the heat sink 10.

  The in-vehicle inverter device 30 includes, for example, a circuit board 41 fixed to the base member 32 and a power module 42 mounted on the circuit board 41. The circuit board 41 is disposed to face the base member 32 at a predetermined interval in the thickness direction of the base member 32, and has a board surface 41 a that faces the base member 32. The substrate surface 41a is a surface on which the power module 42 is mounted.

  The output side of the power module 42 is electrically connected to the coil 23 of the electric motor 20. The power module 42 includes a plurality of switching elements Qu1, Qu2, Qv1, Qv2, Qw1, Qw2 (hereinafter also simply referred to as switching elements Qu1-Qw2). In the present embodiment, the power module 42 corresponds to a “power conversion circuit”.

  A connector 43 is provided on the inverter case 31 (specifically, the cover member 33). Direct current power is supplied from the DC power supply E mounted on the vehicle to the in-vehicle inverter device 30 via the connector 43. The vehicle is provided with a power supply capacitor C0 connected in parallel to the DC power supply E (see FIG. 5). The power supply capacitor C0 is composed of, for example, a film capacitor.

  The in-vehicle inverter device 30 includes two wirings EL1 and EL2 that electrically connect the connector 43 and the input side of the power module 42. The first wiring EL1 is connected to the positive terminal (positive terminal) of the DC power source E via the connector 43 and is connected to the first module input terminal 42a that is the first input terminal of the power module 42. Yes. The second wiring EL2 is connected to the negative terminal of the DC power source E via the connector 43 and to the second module input terminal 42b that is the second input terminal of the power module 42. Yes. The in-vehicle inverter device 30 is configured such that each switching element Qu1 to Qw2 is periodically turned on / off in a situation where direct current power is input to the power module 42 via the two wirings EL1 and EL2. Is converted into AC power, and the AC power is output to the coil 23 of the electric motor 20. As a result, the electric motor 20 is driven.

  Note that the current (in other words, electric power) handled by the in-vehicle inverter device 30 is large enough to drive the electric motor 20, and is larger than the signal current (in other words, electric power). For example, the current handled by the in-vehicle inverter device 30 is 10 A or more, preferably 20 A or more. The DC power source E is an in-vehicle power storage device such as a secondary battery or a capacitor.

  As shown in FIG. 2, the circuit board 41 is formed with a plurality of wiring patterns 41b constituting a part of both wirings EL1, EL2. The wiring pattern 41b is formed in a plurality of layers including, for example, a substrate surface 41a and a surface opposite to the substrate surface 41a. The specific structure of the wiring pattern 41b is arbitrary, and may be, for example, a rod shape such as a bus bar or a flat plate shape.

  Here, the DC power transmitted from the connector 43 toward the power module 42, specifically, the DC power transmitted through both the wirings EL1 and EL2, may include common mode noise and normal mode noise.

  Common mode noise is noise in which currents in the same direction flow through both wirings EL1 and EL2. The common mode noise can occur, for example, when the in-vehicle inverter device 30 and the DC power source E are electrically connected via a path (for example, a vehicle body or the like) other than both the wirings EL1 and EL2. The normal mode noise is noise having a predetermined frequency superimposed on DC power, and when instantaneously viewed, currents flowing in opposite directions through the wirings EL1 and EL2 flow. It can be said that the normal mode noise is an inflow ripple component included in DC power flowing into the in-vehicle inverter device 30. Details of the normal mode noise will be described later.

  On the other hand, the in-vehicle inverter device 30 of the present embodiment is a noise reduction unit that reduces (attenuates) common mode noise and normal mode noise included in DC power transmitted from the connector 43 toward the power module 42. 50. The noise reduction unit 50 is provided on both the wirings EL <b> 1 and EL <b> 2, and the DC power supplied from the connector 43 is input to the power module 42 through the noise reduction unit 50.

The noise reduction unit 50 will be described in detail.
As shown in FIGS. 2 to 4, the noise reduction unit 50 includes a common mode choke coil 51, for example. The common mode choke coil 51 has a core 52 and a first winding 53a and a second winding 53b wound around the core 52.

  The core 52 is formed in, for example, a polygonal (rectangular in this embodiment) ring shape having a predetermined thickness. In other words, the core 52 can be said to be a cylindrical shape having a predetermined height. As shown in FIGS. 2 and 4, the core 52 includes a first winding part 52a around which the first winding 53a is wound, a second winding part 52b around which the second winding 53b is wound, Both windings 53a and 53b are not wound and have an exposed portion 52d where the surface 52c of the core 52 is exposed. Both windings 53a and 53b are arranged to face each other in a state in which the winding axis directions coincide with each other. In the present embodiment, the number of turns (number of turns) of both the windings 53a and 53b is set to be the same.

  In the present embodiment, the core 52 is composed of one part. However, the present invention is not limited to this, and the core 52 may be configured, for example, by connecting two symmetrical parts, or may be configured by three or more parts.

  As shown in FIG. 2, the common mode choke coil 51 includes a first input terminal 61 and a first output terminal 62 drawn from the first winding 53a, and a second input terminal 63 drawn from the second winding 53b. And a second output terminal 64.

  As shown in FIGS. 3 and 5, the first wiring EL <b> 1 used to connect the + terminal of the DC power source E and the power module 42 is the first wiring that connects the connector 43 and the first input terminal 61. A connector-side wiring EL11 and a first module-side wiring EL12 that connects the first output terminal 62 and the first module input terminal 42a are provided.

  The second wiring EL2 used to connect the negative terminal of the DC power source E and the power module 42 includes a second connector-side wiring EL21 that connects the connector 43 and the second input terminal 63, and a second output terminal. 64 and a second module side wiring EL22 for connecting the second module input terminal 42b. As a result, the DC power of the DC power source E is input to the power module 42 through both connector-side wirings EL11 and EL21, both windings 53a and 53b, and both module-side wirings EL12 and EL22. That is, the module-side wirings EL12 and EL22 connect the output side of the common mode choke coil 51 and the input side of the power module 42. In this case, it can be said that the windings 53a and 53b are provided on the wirings EL1 and EL2. Both terminals 61 and 62 can also be said to be both ends of the first winding 53a, and both terminals 63 and 64 can also be said to be both ends of the second winding 53b. Further, the wiring pattern 41b formed on the circuit board 41 constitutes both the connector side wirings EL11 and EL21, and constitutes both the module side wirings EL12 and EL22.

  The common mode choke coil 51 has a relatively large impedance (specifically, an inductance) when a common mode current flows through both wirings EL1 and EL2, and has an impedance when a normal mode current flows through both wirings EL1 and EL2. Is configured to be relatively small. More specifically, the windings 53a and 53b generate magnetic fluxes that reinforce each other when a common mode current, which is a current in the same direction, flows through the wirings EL1 and EL2 (in other words, both windings 53a and 53b). On the other hand, when normal mode currents, which are currents in opposite directions, flow through both wirings EL1, EL2, they are wound so as to generate magnetic fluxes that cancel each other.

  Here, since the exposed portion 52d is provided in the core 52, a leakage magnetic flux is generated in the common mode choke coil 51 in a situation where a normal mode current flows through both the wirings EL1 and EL2. That is, the common mode choke coil 51 has a predetermined inductance with respect to the normal mode current. The leakage magnetic flux is generated around the common mode choke coil 51 and is likely to be concentrated at both ends of the windings 53a and 53b in the winding axis direction.

  As shown in FIGS. 3 and 5, the noise reduction unit 50 includes bypass capacitors 71 and 72 that reduce common mode noise, and a smoothing capacitor 73 that is provided separately from the bypass capacitors 71 and 72. The smoothing capacitor 73 is composed of, for example, a film capacitor or an electrolytic capacitor. The smoothing capacitor 73 forms a low-pass filter circuit 74 in cooperation with the common mode choke coil 51. The low-pass filter circuit 74 reduces normal mode noise flowing from the DC power source E. The low-pass filter circuit 74 is a resonance circuit and can be said to be an LC filter.

  As shown in FIG. 3, the common mode choke coil 51 and the capacitors 71 to 73 are disposed between the board surface 41 a of the circuit board 41 and the base member 32. The common mode choke coil 51 is disposed in a state in which the winding axis direction of both the windings 53a and 53b intersects the opposing direction of the substrate surface 41a and the base member 32 (in detail, orthogonal). In this case, the thickness direction of the core 52 coincides with the facing direction.

  Incidentally, a surface of the core 52 that faces the substrate surface 41a is a core bottom surface 52e, and a surface that faces the base member 32 is a core top surface 52f. Further, a surface that is continuous with both the core upper surface 52f and the core bottom surface 52e of the core 52 and that constitutes the outline of the core 52 is defined as a core outer peripheral surface 52g. A core outer peripheral surface 52g (a side surface of the common mode choke coil 51) intersects a plane (in this embodiment, a plane orthogonal to the thickness direction of the core 52) including the winding axes of both windings 53a and 53b. It is. The core outer peripheral surface 52g is along the magnetic flux flowing through the core 52 and intersects the leakage magnetic flux.

  In the present embodiment, the core outer peripheral surface 52 g is parallel to the thickness direction of the core 52. The core outer peripheral surface 52g intersects with the winding axis direction of both windings 53a and 53b (specifically, orthogonal) and a portion parallel to the winding axis direction of both windings 53a and 53b. And have.

  Further, the side surface of the common mode choke coil 51 is disposed on the core outer peripheral surface 52g (specifically, the portion constituting the exposed portion 52d in the core outer peripheral surface 52g) and the core outer peripheral surface 52g in both windings 53a and 53b. It is composed of parts.

  As shown in FIGS. 2 and 3, the in-vehicle inverter device 30 includes a damping unit 80 that lowers the Q value of the low-pass filter circuit 74. The damping unit 80 configures a magnetic path through which leakage magnetic flux generated from the common mode choke coil 51 flows, thereby increasing the leakage inductance of the common mode choke coil 51 due to the leakage magnetic flux.

  The damping unit 80 is made of a material having a relative permeability higher than that of the inverter case 31. For example, the damping unit 80 is made of a magnetic material including a ferromagnetic material. The relative permeability of the damping unit 80 may be set higher than, for example, “3”.

  Furthermore, the damping part 80 is made of a conductive material having a higher electrical resistivity than the inverter case 31. An example of the damping unit 80 is iron. Incidentally, the inverter case 31 is made of a material having a higher thermal conductivity than that of the damping part 80.

  The damping unit 80 is disposed between the board surface 41 a of the circuit board 41 and the base member 32, and has a bottomed box shape having an opening 80 a that opens toward the base member 32. The damping part 80 covers the entire core bottom surface 52e and the core outer peripheral surface 52g. Specifically, the damping part 80 includes a damping bottom part 81 that covers the core bottom face 52e as the bottom face of the common mode choke coil 51, and a damping side part 82 that covers the core outer peripheral face 52g as the side face of the common mode choke coil 51. I have.

  The damping bottom portion 81 is disposed between the core bottom surface 52 e that is a surface facing the circuit board 41 in the common mode choke coil 51 and the board surface 41 a of the circuit board 41. The damping bottom 81 protrudes from the core outer peripheral surface 52g in the entire circumference of the core outer peripheral surface 52g when viewed from the facing direction of the substrate surface 41a and the base member 32.

  The damping side portion 82 is a wall portion that rises from the damping bottom portion 81 toward the base member 32 side (heat sink 10 side), and faces the core outer peripheral surface 52g. Specifically, the damping side portion 82 includes a first side portion 82a that faces a portion of the core outer peripheral surface 52g that intersects the winding axis direction of the windings 53a and 53b, and the windings 53a and 53b. It has the 2nd side part 82b which opposes a part parallel to a winding axis direction. The front end of the damping side portion 82 protrudes toward the base member 32 from both the windings 53a and 53b. The damping side portion 82 intersects the plane including the winding axis of both the windings 53a and 53b. It can be said that the damping side portion 82 is provided between the side wall of the bottomed cylindrical cover member 33 and the core outer peripheral surface 52g.

  In this embodiment, the damping part 80 covers both the part which comprises the exposed part 52d among the core outer peripheral surfaces 52g, and the part arrange | positioned on the core outer peripheral surface 52g in both winding 53a, 53b. ing. In view of the fact that the side surface of the common mode choke coil 51 is composed of the core outer peripheral surface 52g and the portions of the windings 53a and 53b that are disposed on the core outer peripheral surface 52g, the damping unit 80 has the common mode It can be said that the side surface of the choke coil 51 is covered.

  The spacing between the common mode choke coil 51 and the damping portion 80, specifically, the spacing between the damping bottom portion 81 and the core bottom surface 52e, and the spacing between the damping side portion 82 and the core outer peripheral surface 52g are both windings 53a and 53b. Even in the case where the maximum current flows, the common mode choke coil 51 is set to be short as long as magnetic saturation does not occur.

  The opening 80 a of the damping part 80 is covered with the base member 32 of the inverter case 31, and the accommodation space 83 is partitioned by the damping part 80 and the base member 32. The common mode choke coil 51 is accommodated in the accommodation space 83. The core top surface 52f of the common mode choke coil 51 opposite to the core bottom surface 52e faces the base member 32 and is covered with the base member 32.

  According to such a configuration, the leakage magnetic flux generated from the common mode choke coil 51 flows preferentially in the damping unit 80, but hardly flows to the circuit board 41 and the inverter case 31. Thereby, since the leakage magnetic flux is less likely to diverge, the leakage inductance of the common mode choke coil 51 due to the leakage magnetic flux is high.

  Further, an eddy current is generated in the damping unit 80 due to leakage magnetic flux flowing in the damping unit 80. The eddy current is converted into heat by the damping unit 80. That is, the damping unit 80 functions as a resistance against the leakage magnetic flux. As already described, since the electrical resistivity of the damping unit 80 is higher than the electrical resistivity of the inverter case 31, the resistance value of the damping unit 80 against leakage magnetic flux is higher than the resistance value of the inverter case 31.

  Incidentally, the damping unit 80 and the common mode choke coil 51 are insulated. Although a specific configuration for insulating both is arbitrary, for example, a configuration in which the damping unit 80 and the common mode choke coil 51 are opposed to each other through a gap or an insulating layer is conceivable.

  As shown in FIG. 3, in the present embodiment, the tip of the damping side portion 82 is in contact with the base member 32, and the opening 80 a is closed by the base member 32. Thereby, since the closed part is formed by the damping part 80 and the base member 32 (inverter case 31), an eddy current can be generated suitably. Moreover, the heat of the damping part 80 can be transmitted to the inverter case 31.

  However, the present invention is not limited to this, and the tip of the damping side portion 82 may be separated from the base member 32, or a conductive or insulating inclusion between the tip of the damping side portion 82 and the base member 32. May be present.

  As shown in FIGS. 2 and 3, the damping bottom 81 is formed with a through hole 81 a into which each of the terminals 61 to 64 can be inserted. The terminals 61, 62, 63, 64 are connected to the corresponding wirings EL11, EL12, EL21, EL22 while being inserted through the through holes 81a.

  In addition, although illustration is abbreviate | omitted, the insulating material intervenes between each terminal 61-64 and the inner surface of the through-hole 81a. For this reason, each terminal 61-64 and the damping part 80 are electrically insulated.

  As shown in FIG. 1, the common mode choke coil 51 is disposed at a position farther from the power module 42 than the capacitors 71 to 73. Specifically, each of the capacitors 71 to 73 is disposed between the common mode choke coil 51 and the power module 42.

  The common mode choke coil 51 and the capacitors 71 to 73 are thermally coupled to the heat sink 10. Specifically, the common mode choke coil 51 and the capacitors 71 to 73 are close to the inverter case 31 (base member 32) in contact with the heat sink 10. For example, the distance H1 between the core top surface 52f and the base member 32 is set to be shorter than the distance H2 between the core bottom surface 52e and the circuit board 41. Heat generated in the common mode choke coil 51 and the capacitors 71 to 73 is transmitted to the base member 32 and absorbed by the heat sink 10. As shown in FIG. 3, each of the capacitors 71 to 73 is also provided with a terminal, and the terminal is connected to the wiring pattern 41 b of the circuit board 41.

Next, the electrical configuration of the in-vehicle inverter device 30 will be described with reference to FIGS. 5 and 6.
As already described, the noise reduction unit 50 is provided on the input side of the power module 42 (specifically, the switching elements Qu1 to Qw2). Specifically, the common mode choke coil 51 of the noise reduction unit 50 is interposed between both the connector side wirings EL11 and EL21 and both the module side wirings EL12 and EL22.

  Here, the common mode choke coil 51 generates a leakage magnetic flux when a normal mode current flows. In view of this point, as shown in FIG. 5, the common mode choke coil 51 can be regarded as having virtual normal mode coils L1 and L2 separately from both windings 53a and 53b. That is, the common mode choke coil 51 of this embodiment has both windings 53a and 53b and virtual normal mode coils L1 and L2 in terms of an equivalent circuit. The virtual normal mode coils L 1 and L 2 correspond to the leakage inductance of the common mode choke coil 51. Virtual normal mode coils L1, L2 and windings 53a, 53b are connected in series with each other. Although not shown, the damping unit 80 functions as a resistor that lowers the Q value of the low-pass filter circuit 74.

  In addition to the in-vehicle inverter device 30, for example, a PCU (power control unit) 103 is mounted on the vehicle as in-vehicle equipment. The PCU 103 uses a direct current power supplied from the DC power source E to drive a traveling motor mounted on the vehicle. That is, in this embodiment, the PCU 103 and the in-vehicle inverter device 30 are connected in parallel to the DC power source E, and the DC power source E is shared by the PCU 103 and the in-vehicle inverter device 30. .

  The PCU 103 includes, for example, a boost converter 104 that boosts DC power of the DC power source E by periodically turning on and off the boost switching element, and DC power boosted by the boost converter 104. And a traveling inverter that converts the driving motor to drive power that can be driven.

  In such a configuration, noise generated due to switching of the boost switching element flows into the in-vehicle inverter device 30 as normal mode noise. In other words, the normal mode noise includes a noise component corresponding to the switching frequency of the step-up switching element. Since the switching frequency of the step-up switching element differs depending on the vehicle type, the frequency of normal mode noise varies depending on the vehicle type. The noise component corresponding to the switching frequency of the step-up switching element may include not only a noise component having the same frequency as the switching frequency but also a harmonic component thereof.

  Both bypass capacitors 71 and 72 are connected in series with each other. Specifically, the noise reduction unit 50 includes a bypass line EL <b> 3 that connects one end of the first bypass capacitor 71 and one end of the second bypass capacitor 72. The bypass line EL3 is grounded to the vehicle body.

  The series connection body of the bypass capacitors 71 and 72 is connected in parallel to the common mode choke coil 51. Specifically, the other end of the first bypass capacitor 71 opposite to the one end is connected to the first winding 53a (first output terminal 62) and the power module 42 (first module input terminal 42a). It is connected to one module side wiring EL12. The other end of the second bypass capacitor 72 opposite to the one end is a second module side wiring that connects the second winding 53b (second output terminal 64) and the power module 42 (second module input terminal 42b). It is connected to EL22.

  The smoothing capacitor 73 is provided on the output side of the common mode choke coil 51 and on the input side of the power module 42. Specifically, the smoothing capacitor 73 is provided between the series connection body of the bypass capacitors 71 and 72 and the power module 42, and is connected in parallel to both. Specifically, one end of the smoothing capacitor 73 is connected to the portion from the connection point P1 to the first bypass capacitor 71 in the first module side wiring EL12 to the power module 42, and the other end of the smoothing capacitor 73 is connected to the second module. The side wiring EL22 is connected to a portion from the connection point P2 with the second bypass capacitor 72 to the power module 42.

  As shown in FIG. 6, the coil 23 of the electric motor 20 has a three-phase structure including, for example, a u-phase coil 23u, a v-phase coil 23v, and a w-phase coil 23w. Each coil 23u-23w is Y-connected, for example.

  The power module 42 is an inverter circuit. The power module 42 includes u-phase switching elements Qu1, Qu2 corresponding to the u-phase coil 23u, v-phase switching elements Qv1, Qv2 corresponding to the v-phase coil 23v, and w-phase switching elements Qw1, corresponding to the w-phase coil 23w. Qw2. Each of the switching elements Qu1 to Qw2 is a power switching element such as an IGBT. The switching elements Qu1 to Qw2 include freewheeling diodes (body diodes) Du1 to Dw2.

  The u-phase switching elements Qu1 and Qu2 are connected to each other in series via a connection line, and the connection line is connected to the u-phase coil 23u via a u-phase module output terminal 42u. And direct-current power from DC power supply E is input with respect to the serial connection body of each u-phase switching element Qu1, Qu2. Specifically, the collector of the first u-phase switching element Qu1 is connected to the first module input terminal 42a, and is connected to the first module-side wiring EL12 via the first module input terminal 42a. The emitter of the second u-phase switching element Qu2 is connected to the second module input terminal 42b, and is connected to the second module side wiring EL22 via the second module input terminal 42b.

  The other switching elements Qv1, Qv2, Qw1, and Qw2 have the same connection mode as the u-phase switching elements Qu1 and Qu2, except that the corresponding coils are different. In this case, it can be said that the switching elements Qu1 to Qw2 are connected to the module-side wirings EL12 and EL22.

  Further, the connection line connecting the v-phase switching elements Qv1 and Qv2 in series is connected to the v-phase coil 23v via the v-phase module output terminal 42v, and the w-phase switching elements Qw1 and Qw2 are connected in series. The connecting line to be connected is connected to the w-phase coil 23w via the w-phase module output terminal 42w. That is, the module output terminals 42 u to 42 w of the power module 42 are connected to the electric motor 20.

  The in-vehicle inverter device 30 includes a control unit 90 that controls the power module 42 (specifically, the switching operation of the switching elements Qu1 to Qw2). The controller 90 periodically turns on / off the switching elements Qu1 to Qw2 based on an external command. Specifically, the control unit 90 performs pulse width modulation control (PWM control) on the switching elements Qu1 to Qw2 based on an external command. More specifically, the control unit 90 generates a control signal using a carrier signal (carrier wave signal) and a command voltage value signal (comparison target signal). And the control part 90 converts direct-current power into alternating current power by performing ON / OFF control of each switching element Qu1-Qw2 using the produced | generated control signal.

  The cut-off frequency fc of the low-pass filter circuit 74 is set lower than the carrier frequency f1, which is the frequency of the carrier signal. Note that the carrier frequency f1 can also be said to be the switching frequency of each of the switching elements Qu1 to Qw2.

  Next, the frequency characteristics of the low-pass filter circuit 74 of this embodiment will be described with reference to FIG. FIG. 7 is a graph showing the frequency characteristics of the low-pass filter circuit 74 with respect to the normal mode noise that flows in. Note that the solid line in FIG. 7 indicates the frequency characteristic when the damping unit 80 is present, and the two-dot chain line in FIG. 7 indicates the frequency characteristic when the damping unit 80 is not present.

  As indicated by the two-dot chain line in FIG. 7, when the damping unit 80 is not present, the Q value of the low-pass filter circuit 74 is relatively high. For this reason, normal mode noise having a frequency close to the resonance frequency f 0 of the low-pass filter circuit 74 is difficult to be reduced by the noise reduction unit 50.

  On the other hand, in the present embodiment, since the damping unit 80 exists, the Q value of the low-pass filter circuit 74 is low as shown by the solid line in FIG. For this reason, the normal mode noise having a frequency close to the resonance frequency f 0 of the low-pass filter circuit 74 is also reduced by the noise reduction unit 50.

  Here, as shown in FIG. 7, an allowable value of gain (attenuation rate) G required based on the specification of the vehicle is an allowable gain Gth. The Q value at which the gain G of the low-pass filter circuit 74 becomes the allowable gain Gth when the frequency of the normal mode noise is the same as the resonance frequency f0 is set as the specific Q value. In this configuration, in the present embodiment, the damping unit 80 causes the Q value of the low-pass filter circuit 74 to be lower than the specific Q value. For this reason, the gain G of the low-pass filter circuit 74 when the normal mode noise frequency is the same as the resonance frequency f0 is smaller than the allowable gain Gth (as an absolute value). In other words, the damping unit 80 is configured to lower the Q value of the low-pass filter circuit 74 below the specific Q value.

  Incidentally, the leakage inductance of the common mode choke coil 51 is high due to the presence of the damping unit 80. For this reason, the resonance frequency f0 of the low-pass filter circuit 74 of the present embodiment is lower than that when the damping unit 80 is not provided. As a result, as shown in FIG. 7, the gain G in the frequency band higher than the resonance frequency f <b> 0 is smaller than when the damping unit 80 is not provided. Therefore, normal mode noise in a frequency band higher than the resonance frequency f0 can be more suitably reduced.

According to the embodiment described above in detail, the following effects are obtained.
(1) The in-vehicle inverter device 30 is provided on the input side of the power module 42 that converts DC power into AC power, and noise that reduces common mode noise and normal mode noise included in the DC power. And a reduction unit 50. The noise reduction unit 50 includes a core 52, a first winding 53 a wound around the first winding portion 52 a of the core 52, and a second winding 53 b wound around the second winding portion 52 b of the core 52. A common mode choke coil 51 is provided. The in-vehicle inverter device 30 is configured such that DC power in which common mode noise and normal mode noise are reduced by the common mode choke coil 51 is input to the power module 42. Specifically, the in-vehicle inverter device 30 includes module-side wirings EL12 and EL22 that connect the common mode choke coil 51 and the power module 42.

  According to this configuration, the common mode choke coil 51 reduces common mode noise included in the DC power to be converted by the in-vehicle inverter device 30. Further, the common mode choke coil 51 generates a leakage magnetic flux when a normal mode current flows. Thereby, normal mode noise can be reduced. Therefore, DC power with both common mode noise and normal mode noise reduced can be input to the power module 42 without providing a dedicated coil for reducing normal mode noise. Increase in size can be suppressed.

  (2) The in-vehicle inverter device 30 constitutes a smoothing capacitor 73 constituting a low-pass filter circuit 74 in cooperation with the common mode choke coil 51 and a magnetic path through which leakage magnetic flux generated from the common mode choke coil 51 flows. Accordingly, a damping unit 80 that increases the leakage inductance of the common mode choke coil 51 is provided. The damping unit 80 reduces the Q value of the low-pass filter circuit 74 by generating an eddy current by the leakage magnetic flux. According to such a configuration, the normal mode noise can be suitably reduced by the low-pass filter circuit 74. Further, since the Q value of the low-pass filter circuit 74 can be lowered without providing a damping resistor or the like, it is possible to improve versatility while suppressing an increase in the size of the in-vehicle inverter device 30.

  More specifically, as already described, if the Q value of the low-pass filter circuit 74 is high, normal mode noise close to the resonance frequency f0 of the low-pass filter circuit 74 is difficult to be reduced. For this reason, the low-pass filter circuit 74 having a high Q value may not function effectively for normal mode noise having a frequency close to the resonance frequency f0. Therefore, there is a concern about malfunction of the in-vehicle inverter device 30 and a decrease in the lifetime of the low-pass filter circuit 74, and there arises a problem that it cannot be applied to a vehicle type that generates normal mode noise having a frequency close to the resonance frequency f0. On the other hand, in this embodiment, since the Q value is lowered by the damping unit 80, normal mode noise having a frequency close to the resonance frequency f0 is reduced by the noise reduction unit 50 (specifically, the low-pass filter circuit 74). easy. Thereby, the frequency band of the normal mode noise that can be reduced by the noise reduction unit 50 can be widened, and through this, the in-vehicle inverter device 30 can be applied to a wide variety of vehicle types.

  Here, for example, in order to lower the Q value, a damping resistor may be provided in series with the common mode choke coil 51. However, since the damping resistor needs to cope with a relatively high current of 10 A or more, it tends to be relatively large, and the power loss and the amount of heat generation tend to be large. For this reason, it is necessary to install a damping resistor in consideration of heat dissipation and the like, and there is a concern about increasing the size of the in-vehicle inverter device 30. On the other hand, in the present embodiment, an eddy current is generated in the damping unit 80, but since the eddy current is lower than the current flowing through the damping resistor, the amount of heat generated in the damping unit 80 tends to be small. From the above, it is possible to improve versatility while achieving both suppression of increase in size of the in-vehicle inverter device 30 and reduction of both noises.

  In particular, since the leakage inductance is increased by the damping unit 80, the resonance frequency f0 of the low-pass filter circuit 74 can be lowered. As a result, the gain G in the frequency band higher than the resonance frequency f0 is likely to be smaller than in the configuration without the damping unit 80. Therefore, normal mode noise in a frequency band higher than the resonance frequency f0 can be further reduced.

  (3) The damping portion 80 covers the side surface of the common mode choke coil 51, specifically, the core outer peripheral surface 52g and the portion disposed on the core outer peripheral surface 52g in both windings 53a and 53b. The core outer peripheral surface 52g is a surface intersecting with a plane including the winding axis of both the windings 53a and 53b. Thereby, the damping part 80 functions as a resistance against the leakage magnetic flux. Therefore, the effect (2) can be realized with a relatively simple configuration.

  (4) The in-vehicle inverter device 30 includes an inverter case 31 in which a circuit board 41 on which a wiring pattern 41b is formed, a power module 42, and a noise reduction unit 50 are accommodated. The damping unit 80 is made of a material having a relative permeability higher than that of the inverter case 31. According to such a configuration, the leakage magnetic flux is more easily guided to the damping unit 80 than the inverter case 31. Thereby, it can suppress that a leakage magnetic flux diverges toward the inverter case 31, and the leakage inductance of the common mode choke coil 51 can be made high.

  (5) The damping unit 80 is made of a material having a higher electrical resistivity than the inverter case 31. According to such a configuration, since the resistance value of the damping unit 80 can be made higher than the resistance value of the inverter case 31, the damping effect by the damping unit 80 can be further enhanced. Thereby, the Q value of the low-pass filter circuit 74 can be further lowered.

  (6) The damping part 80 has a bottomed box shape having an opening 80 a covered by the inverter case 31, and the common mode choke coil 51 is placed in the accommodation space 83 defined by the damping part 80 and the inverter case 31. Contained. As a result, the surfaces other than the core upper surface 52f corresponding to the opening 80a in the core 52 (specifically, the core outer peripheral surface 52g and the core bottom surface 52e) are covered by the damping unit 80, and thus the low-pass while increasing the leakage inductance more suitably. The Q value of the filter circuit 74 can be lowered.

  (7) The inverter case 31 has a higher thermal conductivity than the damping unit 80. And the damping part 80 and the inverter case 31 are comprised so that heat exchange is possible, and both are contacting in detail. According to such a configuration, the heat of the damping unit 80 generated by the eddy current can be suitably transmitted to the inverter case 31.

  (8) The power module 42 has a plurality of switching elements Qu1 to Qw2, and converts the DC power into AC power by PWM control of the plurality of switching elements Qu1 to Qw2. The cut-off frequency fc of the low-pass filter circuit 74 is set lower than the carrier frequency f1, which is the frequency of the carrier signal used for PWM control of the switching elements Qu1 to Qw2. As a result, ripple noise (normal mode noise generated in the power module 42) resulting from switching of each of the switching elements Qu1 to Qw2 is reduced (attenuated) by the low-pass filter circuit 74. Therefore, the ripple noise is reduced to an in-vehicle inverter. Outflow to the outside of the device 30 can be suppressed. That is, the low-pass filter circuit 74 functions to reduce normal mode noise and common mode noise flowing into the in-vehicle inverter device 30 during the operation of the PCU 103, and ripple noise flows out during the operation of the in-vehicle inverter device 30. Acts as a reduction.

  Here, focusing on the viewpoint of widening the frequency band of normal mode noise that can be reduced by the noise reduction unit 50, in order to avoid the occurrence of a resonance phenomenon, the resonance frequency f0 is assumed to be the frequency band of the assumed normal mode noise. It is also possible to make it higher. However, in this case, since the cutoff frequency fc of the low-pass filter circuit 74 is also increased, it is difficult to make the cutoff frequency fc lower than the carrier frequency f1 as described above. However, increasing the carrier frequency f1 as the cut-off frequency fc increases is not preferable because the switching loss of each of the switching elements Qu1 to Qw2 increases.

  On the other hand, in the present embodiment, since the normal mode noise having a frequency close to the resonance frequency f0 can be reduced by the damping unit 80 as described above, the resonance frequency f0 is set to the assumed normal mode. There is no need to increase the frequency according to the noise frequency band. Therefore, the cut-off frequency fc can be made lower than the carrier frequency f1 without excessively increasing the carrier frequency f1. Therefore, it is possible to suppress the ripple noise caused by the switching of the switching elements Qu <b> 1 to Qw <b> 2 from flowing out of the in-vehicle inverter device 30 while suppressing an increase in power loss of the power module 42.

  In particular, in this embodiment, since the leakage inductance is increased by the damping unit 80, the resonance frequency f0 is decreased. Thereby, the cut-off frequency fc can be made lower than the carrier frequency f1 relatively easily. In other words, the damping unit 80 also functions as a configuration for making the cutoff frequency fc lower than the carrier frequency f1.

  (9) The core 52 includes a first winding part 52a around which the first winding 53a is wound, a second winding part 52b around which the second winding 53b is wound, and both windings 53a and 53b. An exposed portion 52d that is not wound and has an exposed surface 52c. As a result, when a normal mode current flows through both wirings EL1, EL2 (specifically, both windings 53a, 53b), leakage magnetic flux is likely to occur. Therefore, the effect (1) can be obtained.

In addition, you may change the said embodiment as follows.
As shown in FIG. 8, both windings 110 and 111 may be wound around the entire core 52. In this case, the windings 110 and 111 may have high density portions 110a and 111a and low density portions 110b and 111b having relatively different winding densities. The winding density is the number of turns (number of turns) per unit length in the winding axis direction. Even in this case, leakage magnetic flux is likely to be generated from the common mode choke coil 51. Note that either the first winding 110 or the second winding 111 may have a high density portion and a low density portion. In this case, both the exposed portion and the low density portion coexist. In short, it is sufficient that at least one of the first winding 110 and the second winding 111 has a high density portion and a low density portion.

  The shape of the damping unit 80 is not limited to that of the above embodiment. For example, the damping unit 80 may be a box shape that is interposed between the core upper surface 52f and the base member 32 and includes an upper surface cover portion that covers the core upper surface 52f. The damping part 80 does not have to be a completely closed box shape. For example, a gap (slit) is formed between the first side part 82a and the second side part 82b, or a through hole is formed. It may be. Further, at least a part of the damping part 80 may have a mesh shape, and at least a part of the damping part 80 may have a recess, an emboss, a punching hole, or the like. Furthermore, the damping part 80 may have a frame shape in which the damping bottom part 81 is omitted.

  Moreover, although the damping side part 82 covered the whole core outer peripheral surface 52g, it is not restricted to this, The structure which covers a part of core outer peripheral surface 52g may be sufficient. For example, either the first side part 82a or the second side part 82b may be omitted. Further, the damping part 80 covers only the part of the side surface of the common mode choke coil 51 that constitutes the exposed part 52d of the core outer peripheral surface 52g, and is disposed on the core outer peripheral surface 52g of the windings 53a and 53b. It is good also as a structure which does not cover, and the contrary may be sufficient. Further, the damping part 80 may be configured to cover a part or all of the part constituting the exposed part 52d in the core outer peripheral surface 52g, and is disposed on the core outer peripheral surface 52g in both the windings 53a and 53b. The structure which covers a part or all of the part which exists may be sufficient. In short, the damping unit 80 may cover at least a part of the side surface of the common mode choke coil 51. A damping part may be provided inside the core 52. In other words, the damping unit 80 may be opposed to at least a part of the common mode choke coil 51 so as to constitute a magnetic path through which leakage magnetic flux generated from the common mode choke coil 51 flows.

  The through-hole through which each terminal 61-64 is inserted is formed in the damping side part 82, and the structure extended toward the side may be sufficient as each terminal 61-64. Even in this case, it can be said that the damping side portion 82 covers the entire core outer peripheral surface 52g.

  As shown in FIG. 9, the damping part 130 may be configured to have a damping side part 131 that stands up from the base member 32 and surrounds the core outer peripheral surface 52g. That is, the damping unit may be configured separately from the inverter case 31 or may be integrated with the inverter case 31.

  The installation position of the common mode choke coil 51 and the damping unit 80 is arbitrary as long as it is within the inverter case 31. For example, as shown in FIG. 10, the common mode choke coil 51 and the damping unit 80 are not seen between the board surface 41 a and the base member 32 of the circuit board 41 but viewed from the opposing direction of the board surface 41 a and the base member 32. The circuit board 41 may be disposed at a position protruding laterally.

  Further, as shown in FIG. 10, the common mode choke coil 51 may be arranged in a state where the facing direction and the thickness direction of the core 52 intersect (orthogonal). In this case, the damping part 80 should just be arrange | positioned so that the opening part 80a may be covered by the cover member 33. FIG.

  The common mode choke coil 51 is erected between the substrate surface 41a and the base member 32 in a state where the winding axis direction of both the windings 53a and 53b is aligned with the opposing direction of the substrate surface 41a and the base member 32. It may be in between.

  ○ Boost converter 104 may be omitted. In this case, as the normal mode noise, for example, noise caused by the switching frequency of the switching element of the traveling inverter can be considered.

  A non-magnetic housing case (for example, a resin case) having an insulating property for housing the common mode choke coil 51 may be provided separately. In this case, the damping part is preferably made of a ferromagnetic conductive material and covers the common mode choke coil 51 together with the housing case.

  ○ The base member 32 may be omitted. In this case, the ends of both the windings 53a and 53b and the damping side portion 82 and the heat sink 10 may be close to or in contact with each other through a gap or an insulating layer.

  For example, in a configuration in which an annular rib rising from the outer surface of the heat sink 10 is provided, a plate-like inverter cover member may be attached in a state of being abutted with the rib instead of the inverter case. In this case, a storage chamber in which various components such as the circuit board 41, the power module 42, and the noise reduction unit 50 are stored may be formed by the heat sink 10, the rib, and the inverter cover member. In short, the specific configuration for partitioning the storage chamber is arbitrary.

  ○ The shape of the core 52 is arbitrary. For example, a UU core, an EE core, a toroidal core, or the like may be used as the core. Moreover, the core does not need to be a completely closed ring shape, and may have a configuration in which a gap is formed. The core outer peripheral surface 52g may be a curved surface.

  O Both module side wirings EL12 and EL22 may be omitted, and both output terminals 62 and 64 of the common mode choke coil 51 may be directly connected to both module input terminals 42a and 42b of the power module 42. Further, the smoothing capacitor 73 and the like may be directly connected to both output terminals 62 and 64.

  O The drive target of the electric motor 20 is arbitrary, such as a traveling motor mounted on a vehicle. When the driving target of the electric motor 20 is a traveling motor and the DC power source E is an in-vehicle power storage device, the voltage of the DC power source E is boosted by a boosting circuit and then the in-vehicle inverter device 30 is used. Power conversion may be performed.

  The in-vehicle device is not limited to the PCU 103 and may be any device as long as it has a switching element that is periodically turned ON / OFF. For example, the in-vehicle device may be an inverter provided separately from the in-vehicle inverter device 30.

  The specific circuit configuration of the noise reduction unit 50 is not limited to that of the above embodiment. For example, the smoothing capacitor 73 may be omitted, or two smoothing capacitors 73 may be provided. Further, the positions of the bypass capacitors 71 and 72 and the smoothing capacitor 73 may be replaced, or the bypass capacitors 71 and 72 may be provided at the front stage (connector 43 side) of the common mode choke coil 51. Further, the low-pass filter circuit is arbitrary such as π type or T type.

  The power module 42 of the embodiment is an inverter circuit, but is not limited thereto, and may be a DC / DC converter circuit. In short, the power conversion circuit may be any circuit that performs DC power conversion.

Each said other example may be combined and each said other example and the said embodiment may be combined suitably.
(Second Embodiment)
Next, the second embodiment will be described focusing on differences from the first embodiment and each of the other examples.

11, 12 and 13 show the structure of the noise reduction unit (damping unit 200) in the second embodiment.
In the first embodiment, as shown in FIGS. 2 and 3, the damping unit 80 has a bottomed box shape having an opening 80 a covered with the inverter case 31, and the common mode choke coil 51 is connected to the damping unit 80. In addition, the Q value of the low-pass filter circuit 74 is lowered while increasing the leakage inductance of the common mode choke coil 51 by being accommodated in the accommodating space 83 partitioned by the inverter case 31. At this time, when the common mode choke coil 51 is mounted on the circuit board 41, it may be difficult to cover the six surfaces with metal.

  In the second embodiment, the common mode choke coil 51 is plated so that the common mode choke coil 51 is covered with the conductive metal film 210 for shielding, and the damping unit 200 includes at least one of the common mode choke coil 51. It consists of a conductive metal film 210 for shielding that covers the part. When plating is performed, insulation is ensured by interposing a coating insulating film 211 so that the conductive metal film for shielding 210 by plating adheres to the common mode choke coil 51. Thereby, the same effect as the case where the six surfaces of the common mode choke coil 51 are covered with metal can be obtained.

This will be described in detail below.
The common mode choke coil 51 is at least partially covered with a shielding conductive metal film 210. The shielding conductive metal film 210 is made of an iron plating film, and the shielding conductive metal film 210 is made of a magnetic material (for example, a ferromagnetic material). An insulating film 211 is interposed between the shielding conductive metal film 210 and the common mode choke coil 51. That is, although it is difficult to plate the core 52 directly, an insulating film 211 such as a resin as a coating material is formed on the surface of the core 52, and plating is performed on the surface to form the conductive metal film 210 for shielding. Forming. Further, the surface of the shielding conductive metal film 210 is covered with an insulating film 212. For details on the insulating film 212, the windings 53 a and 53 b are used in which the conductive wires are covered with the insulating film. However, by further covering with the insulating film 212, the insulating films 212 become more excellent in insulation (double insulation). The quality can be improved by adopting a structure). In this way, the conductive metal film 210 for shielding is formed through the insulating film 211 with the windings 53a and 53b wound around the core 52, and the conductive metal film 210 for shielding is covered with the insulating film 212. Thus, the common mode choke coil 51 is covered with a three-layer film of the insulating film 211, the shielding conductive metal film 210, and the insulating film 212.

  Moreover, the damping part 80 in 1st Embodiment has the through-hole 81a which can insert each terminal 61-64 in the damping bottom part 81 as FIG.2 and FIG.3 shows, and the terminal 61 is inserted in the through-hole 81a. Since it is a structure which passes -64, the device which ensures insulation is required. On the other hand, in the second embodiment, a through hole for inserting a terminal can be eliminated.

  Note that the common mode choke coil 51 may be entirely covered with the shielding conductive metal film 210 or a part thereof may be covered with the shielding conductive metal film 210. Further, the shielding conductive metal film 210 is not limited to a plating film, and may be a metal film formed by coating, for example. Further, only one of the insulating film 211 and the insulating film 212 may be applied.

(Third embodiment)
Next, the third embodiment will be described focusing on differences from the first embodiment and each of the other examples.
14 and 15 show the structure of the noise reduction unit (damping unit 300) in the third embodiment.

  In the first embodiment, as shown in FIGS. 2 and 3, the common mode choke coil 51 is accommodated in the accommodating space 83 defined by the bottomed box-shaped damping part 80 having the opening 80 a and the inverter case 31. Thus, the Q value of the low-pass filter circuit 74 is lowered while increasing the leakage inductance of the common mode choke coil 51. At this time, when the common mode choke coil 51 is mounted on the circuit board 41, it may be difficult to cover the six surfaces with metal.

  In the third embodiment, with respect to the space for accommodating the common mode choke coil 51, one of the six surfaces is covered with the conductive metal film (iron foil) 320 of the circuit board 41, and the other five surfaces are used for shielding. It is covered with a conductive metal case 310. In other words, the circuit board 41 on which the wiring pattern is formed is provided, and the damping part 300 is a conductive metal case for shielding fixed to the circuit board 41 in a state in which the common mode choke coil 51 is accommodated from the open one surface 311. 310 and a conductive metal film 320 for shielding formed in a region inside the opening of the conductive metal case 310 for shielding in the circuit board 41, that is, a region inside the one surface 311 that opens. Thereby, the same effect as the case where the six surfaces of the common mode choke coil 51 are covered with metal can be obtained.

This will be described in detail below.
The shielding conductive metal case 310 has a substantially rectangular parallelepiped box shape with one surface 311 opened. The shield conductive metal case 310 is made of iron, and the shield conductive metal case 310 is made of a conductive material of a magnetic material (for example, a ferromagnetic material). The shield conductive metal case 310 is fixed to the circuit board 41 in a state in which the common mode choke coil 51 is accommodated from the open one surface 311. A plurality of mounting leg portions 312 extending linearly toward the circuit board 41 are provided on the opening surface of the conductive metal case 310 for shielding.

  On the other hand, a conductive metal film 320 for shielding is formed on the circuit board 41 serving as an opening of the conductive metal case 310 for shielding. The surface of the shielding conductive metal film 320 is covered with an insulating film 321. The insulating film 321 is a resist film. The shield conductive metal film 320 is made of iron foil, and the shield conductive metal film 320 is made of a conductive material of a magnetic material (for example, a ferromagnetic material). The circuit board 41 has through holes 330 at positions corresponding to the mounting legs 312 of the conductive metal case 310 for shielding. The shield conductive metal case 310 is attached to the circuit board 41 by inserting the mounting leg portions 312 of the shield conductive metal case 310 into the through holes 330 of the circuit board 41. The mounting leg portion 312 is prevented from coming off in a state where the mounting leg portion 312 passes through the through hole 330 by a retaining portion (claw portion) 312a at the tip.

  In addition, a through hole 340 is formed in the circuit board 41 at a position corresponding to the terminals 61 to 64 of the common mode choke coil 51. Terminals 61 to 64 of the common mode choke coil 51 are inserted into the through holes 340 of the circuit board 41. The terminals 61 to 64 are soldered to the wiring pattern 41b at the front end portion after penetrating from the circuit board 41.

  The damping part 80 in 1st Embodiment had the through-hole 81a which can insert each terminal 61-64 in the damping bottom part 81, as FIG.2 and FIG.3 shows. On the other hand, in the third embodiment, the terminals 61 to 64 pass through the openings of the shielding conductive metal case 310, thereby eliminating the need for through holes for terminal insertion in the shielding conductive metal case 310. Can do.

  Note that the conductive metal film 320 for shielding is not limited to the iron foil, and may be configured using, for example, an iron plating film. Further, an insulating film may be interposed between the shielding conductive metal film 320 and the circuit board 41.

Next, a preferable example that can be grasped from the embodiment and another example will be described below.
(A) The damping portion may be formed of a ferromagnetic conductive material.
(B) When the Q value of the low-pass filter circuit in which the gain of the low-pass filter circuit with respect to normal mode noise having the same frequency as the resonance frequency of the low-pass filter circuit is an allowable gain set based on the specifications of the vehicle is a specific Q value, damping The unit may be configured to lower the Q value of the low-pass filter circuit below the specific Q value.

  DESCRIPTION OF SYMBOLS 10 ... Heat sink, 20 ... Electric motor, 30 ... In-vehicle inverter apparatus (in-vehicle power converter), 31 ... Inverter case (case), 41 ... Circuit board, 41b ... Wiring pattern, 42 ... Power module (Power conversion Circuit), 50 ... noise reduction part, 51 ... common mode choke coil, 52 ... core, 52a ... first winding part, 52b ... second winding part, 52c ... core surface, 52d ... exposed part, 52g ... core Outer peripheral surface, 53a, 110 ... first winding, 53b, 111 ... second winding, 71, 72 ... bypass capacitor, 73 ... smoothing capacitor, 74 ... low pass filter circuit, 80, 130 ... damping part, 80a ... opening 83 ... Accommodating space, 103 ... PCU, 110a, 111a ... High density part, 110b, 111b ... Low density part, 200 ... Damping part, 210 ... Conductive metal film for yield, 300 ... damping part, 310 ... conductive metal case for shield, 320 ... conductive metal film for shield, f0 ... resonance frequency of low-pass filter circuit, f1 ... carrier frequency, fc ... cut-off frequency, Qu1 to Qw2 ... switching elements of the power module.

Claims (7)

A power conversion circuit that performs power conversion of DC power;
A noise reduction unit which is provided on the input side of the power conversion circuit and reduces common mode noise and normal mode noise included in the DC power;
With
The noise reduction unit is
A common mode choke coil having a core, a first winding wound around the first winding portion of the core, and a second winding wound around the second winding portion of the core;
A smoothing capacitor that forms a low-pass filter circuit in cooperation with the common mode choke coil;
With
DC power for which common mode noise and normal mode noise are reduced by the noise reduction unit is an in-vehicle power conversion device that is input to the power conversion circuit,
A damping unit that lowers the Q value of the low-pass filter circuit by generating eddy currents due to leakage magnetic flux generated from the common mode choke coil;
The on-vehicle power converter according to claim 1, wherein the damping unit increases a leakage inductance of the common mode choke coil by forming a magnetic path through which the leakage magnetic flux flows.   The in-vehicle power conversion device according to claim 1, wherein the damping unit covers at least a part of a side surface of the common mode choke coil. A circuit board on which a wiring pattern is formed;
A case in which the power conversion circuit, the circuit board, and the noise reduction unit are accommodated;
With
The in-vehicle power converter according to claim 1, wherein the damping unit is made of a material having a relative permeability higher than that of the case.   The in-vehicle power conversion device according to claim 3, wherein the damping unit is made of a material having a higher electrical resistivity than the case. The damping part is a bottomed box shape having an opening covered by the case,
The in-vehicle power converter according to claim 3 or 4, wherein the common mode choke coil is housed in a housing space partitioned by the damping portion and the case.   The in-vehicle power converter according to claim 1, wherein the damping part is made of a conductive metal film for shielding that covers at least a part of the common mode choke coil. Provided with a circuit board on which a wiring pattern is formed,
The damping part includes a conductive metal case for shielding fixed to the circuit board in a state in which the common mode choke coil is accommodated from one side of the opening, and an inner side of the opening part of the conductive metal case for shielding in the circuit board. The in-vehicle power conversion device according to claim 1 or 2, comprising a conductive metal film for shielding formed in a region to be formed.