Electric compressor

Abstract

An electric compressor (10) comprises a compression part (13), a motor (14), and an inverter device (15). The inverter device (15) has an inverter circuit unit (43) and a noise reduction unit (50) that reduces common-mode noise and differential-mode noise. The noise reduction unit (50) has a common-mode choke coil (51) that has a core (60), a first winding wire (61), and a second winding wire (62) and reduces common-mode noise, a smoothing capacitor (52), and a magnetic material damping section (55) in which an eddy current is induced by a leakage magnetic flux leaking from the core (60). The magnetic material damping section (55) reduces differential-mode noise. The noise reduction unit (50) has a plurality of the magnetic material damping sections (55).The plurality of magnetic material damping sections (55) are stacked with an insulation layer (73) disposed therebetween.

Description

BACKGROUND OF THE INVENTIONThe present invention relates to an electric compressor.An electric compressor for a vehicle mounted on the vehicle such as an electric vehicle is disclosed in Japanese Patent No. JP 6 673 468 B2. The electric compressor for the vehicle includes a compressing part that compresses a fluid, a motor that drives the compressing part, and an inverter device that drives the motor. The inverter device includes an inverter circuit unit and a noise reduction unit. The inverter circuit unit converts a DC power into an AC power. The noise reduction unit is provided at an input side of the inverter circuit unit. The noise reducing unit reduces common mode noise and differential mode noise.The noise reduction unit includes a common mode choke coil, a smoothing capacitor, and an attenuation portion. The common mode choke coil includes a core formed in an annular shape, a first winding wire wound around the core, and a second winding wire wound around the core and disposed adjacent to the first winding wire at a distance. The common mode choke coil reduces common mode noise. The smoothing capacitor forms a low-pass filter circuit together with the common mode choke coil. The damping portion is made of a magnetic material. The attenuation portion is disposed around the common mode choke coil.When a push-pull current flows through the first winding wire and the second winding wire, a magnetic flux leaks from the core. The leakage magnetic flux leaking from the core flows through the damping portion to induce an eddy current in the damping portion. The eddy current induced in the damping portion is converted into thermal energy. This provides a damping effect. The attenuation portion reduces the push-pull noise.In the background of a higher power supply voltage along with the spread of an electric vehicle or the like and other factors, a current input to a common mode choke coil (hereinafter referred to as "input current") increases. For this reason, it is necessary to ensure attenuation resistance when a large current is input to the common mode choke coil.SUMMARYAccording to an aspect of the present invention, there is provided an electric compressor including a compressing part configured to compress a fluid, a motor configured to drive the compressing part, and an inverter device configured to drive the motor. The inverter device includes an inverter circuit unit that converts a DC power into an AC power, and a noise reducing unit that is provided at an input side of the inverter circuit unit and reduces common mode noise and differential mode noise. The noise reducing unit includes a common mode choke coil including a core formed in an annular shape, a first winding wire wound around the core and a second winding wire wound around the core and disposed adjacent to the first winding wire at a distance, the common mode choke coil reducing the common mode noise, a smoothing capacitor forming a low pass filter circuit together with the common mode choke coil, and a magnetic material attenuation portion made of a plate-shaped magnetic material and in which an eddy current is induced by a leakage magnetic flux leaking from the core, the magnetic material attenuation portion reducing the differential mode noise. The noise reduction unit includes a plurality of magnetic material attenuation portions. The plurality of magnetic material attenuation portions are stacked with an insulation layer disposed between the magnetic material attenuation portions.Other features and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.BRIEF DESCRIPTION OF THE DRAWINGThe invention, together with objects and attendant advantages, may best be understood by reference to the following description of the embodiments, taken in conjunction with the accompanying drawings. The following are shown: FIG. 1 is a cross-sectional side view illustrating an electric compressor according to a first embodiment; FIG. 2 is a circuit diagram illustrating an electrical configuration of the electric compressor; FIG. 3 is a perspective view illustrating a part of a holder and a magnetic material damping portion; FIG. 4 is a perspective view illustrating a common mode choke coil; FIG. 5 is a front view at (a) illustrating a part of the electric compressor according to the first embodiment, and FIG. 5 is an enlarged view at (b) of FIG. 5 at (a); FIG. 6 is a cross-sectional view illustrating a part of the electric compressor according to the first embodiment; FIG. 7 is a graph showing a relationship between an input current input to the common mode choke coil and an attenuation resistance; FIG. 8 is an exploded perspective view illustrating the common mode choke coil and a non-magnetic material attenuation portion; FIG. 9 is a front view illustrating a part of an electric compressor according to a second embodiment at (a), and FIG. 9 ( b) is an enlarged side view of FIG. 9 at (a); FIG. 10 is a cross-sectional view illustrating a part of the electric compressor according to the second embodiment; and FIG. 11 is a graph showing the relationship between an input current input to a common mode choke coil and a total attenuation resistance of the magnetic material attenuation portion and the non-magnetic material attenuation portion.DETAILED DESCRIPTION OF THE EMBODIMENTSA first embodiment of an electric compressor will be described with reference to FIGS. 1 to 7. The electric compressor is mounted on a vehicle such as an electric vehicle. The electric compressor according to the first embodiment is used in a vehicle air conditioner.As illustrated in FIG. 1, a vehicle air conditioner 100 includes an electric compressor 10 and an external refrigerant circuit 101. The external refrigerant circuit 101 supplies a refrigerant as a fluid to the electric compressor 10. The external refrigerant circuit 101 includes, for example, a heat exchanger, an expansion valve, or the like, which are not illustrated. The vehicle air conditioner 100 performs heating and cooling of a vehicle interior by the electric compressor 10 compressing the refrigerant and the external refrigerant circuit 101 by which heat is exchanged from or to the refrigerant and the refrigerant is expanded.The vehicle air conditioner 100 includes an air conditioner ECU 102. The air conditioner ECU 102 controls the entire vehicle air conditioner 100. The air conditioner ECU 102 is configured to obtain an in-vehicle temperature and a setting temperature of the vehicle air conditioner 100. The air conditioner ECU 102 sends various commands such as ON / OFF commands to the electric compressor 10 based on parameters such as the temperature inside the vehicle and the setting temperature of the vehicle air conditioner 100.< Compressor>The electric compressor 10 includes a housing 11, a rotation shaft 12, a compression part 13 that compresses the refrigerant, a motor 14 that drives the compression part 13, and an inverter device 15 that drives the motor 14.The rotating shaft 12, the compressing part 13, the motor 14, and the inverter device 15 are accommodated in the housing 11. The housing 11 is made of metal. The housing 11 according to the first embodiment is made of aluminum. The housing 11 is grounded to a body of the vehicle. The housing 11 includes a suction housing 21, an exhaust housing 22, and an inverter housing 23.The suction housing 21 has an end wall 21 aformed in a plate shape and a peripheral wall 21 bformed in a tubular shape extending from an outer peripheral portion of the end wall 21 a. The exhaust housing 22 is connected to an end portion of the suction housing 21 at an opening side thereof. The discharge housing 22 closes the opening of the suction housing 21, and the suction housing 21 and the discharge housing 22 define a suction chamber S 1. The rotating shaft 12, the compressing part 13, and the motor 14 are accommodated in the suction chamber S 1. The motor 14 is disposed between the compressing part 13 and the end wall 21 aof the suction housing 21 in the suction chamber S 1.The inverter case 23 has an end wall 23 aformed in a plate shape and a peripheral wall 23 bformed in a tubular shape extending from an outer peripheral portion of the end wall 23 a. The inverter case 23 is connected to the end wall 21 aof the suction case 21 by bolts B. The end wall 21 aof the suction housing 21 and the inverter housing 23 define an inverter accommodating chamber S 2. The inverter device 15 is accommodated in the inverter accommodating chamber S 2.A connector 16 is attached to the end wall 23 aof the inverter case 23. The connector 16 is electrically connected to a power storage device 103 mounted on the vehicle. The power storage device 103 is a power supply from which power is supplied to an apparatus mounted on the vehicle. The power storage device 103 is a DC power supply. The power storage device 103 is, for example, a rechargeable battery or a capacitor.The housing 11 has a suction port 11 a. The suction port 11 ais formed in the peripheral wall 21 bof the suction housing 21. The suction port 11 ais disposed closer to the end wall 21 athan the exhaust housing 22 is in the peripheral wall 21 bof the suction housing 21. The housing 11 also has an ejection opening 11b. The ejection opening 11 bis formed in the ejection housing 22. The suction port 11 ais connected to one end of the external refrigerant circuit 101, and the discharge port 11 bis connected to the other end of the external refrigerant circuit 101.The rotary shaft 12 is rotatably supported by the housing 11. An axial direction of the rotary shaft 12 coincides with an axial direction of the peripheral wall 21 bof the suction housing 21.The compressing part 13 is connected to the rotating shaft 12. The compressing part 13 compresses the refrigerant as the rotating shaft 12 rotates. The compression part 13 is a screw-type compression part formed of a fixed screw fixed to the suction housing 21 and a revolving screw disposed so as to oppose the fixed screw. Illustrations of the fixed scroll and the revolving scroll are omitted.The motor 14 includes a rotor 31 and a stator 32.The rotor 31 includes a rotor core 33 formed in a cylindrical shape and permanent magnets provided in the rotor core 33. Illustrations of the permanent magnets are not illustrated. The rotating shaft 12 is inserted into the rotor core 33. The rotating shaft 12 is fixed to the rotor core 33. The rotary shaft 12 rotates integrally with the rotor 31.The stator 32 faces the rotor 31 in a radial direction of the rotary shaft 12. The stator 32 includes a stator core 34 formed in a cylindrical shape, a u-phase coil 35 u, a v-phase coil 35 v, and a w-phase coil 35 w. The stator core 34 is fixed to the inner peripheral surface of the peripheral wall 21 bof the suction housing 21. The u-phase coil 35 u, the v-phase coil 35 v, and the w-phase coil 35 ware wound around the stator core 34.As illustrated in FIG. 2, the u-phase coil 35 u, the v-phase coil 35 v, and the w-phase coil 35 ware connected as in a Y connection. A configuration of connection of the u-phase coil 35 u, the v-phase coil 35 v, and the w-phase coil 35 wis not limited to the Y connection, and may be appropriately selected. The configuration of connection of the u-phase coil 35 u, the v-phase coil 35 v, and the w-phase coil 35 wmay be connected in a triangular connection, for example.A current flows through the u-phase coil 35 u, the v-phase coil 35 v, and the w-phase coil 35 win a predetermined pattern, which rotates the rotor 31. The rotation shaft 12 rotates with the rotation of the rotor 31, which drives the compression part 13. Thus, the motor 14 drives the compressing part 13. The compression part 13 compresses the refrigerant sucked into the suction chamber S 1 from the external refrigerant circuit 101 through the suction port 11 a. The refrigerant compressed by the compressing part 13 is discharged to the external refrigerant circuit 101 through the discharge port 11 b.< Device>As illustrated in FIGS. 1 and 2, the inverter device 15 includes a circuit board 41, a holder 42, an inverter circuit unit 43, a control unit 44, and a noise reduction unit 50.As illustrated in FIG. 1, the circuit board 41 is disposed between the end wall 21 aof the suction housing 21 and the end wall 23 aof the inverter housing 23 in the axial direction of the rotation shaft 12. A thickness direction of the circuit board 41 coincides with the axial direction of the rotation shaft 12.The holder 42 is made of a resin. The holder 42 is disposed between the circuit board 41 and the end wall 21a of the suction housing 21.The holder 42 includes a main body portion 45 formed in a plate shape. A thickness direction of the main body portion 45 coincides with the axial direction of the rotating shaft 12. The main body portion 45 has a first surface 45 aand a second surface 45 b. The first surface 45 aand the second surface 45 bare surfaces perpendicular to the thickness direction of the main body portion 45. The first surface 45 aof the main body portion 45 is positioned to be opposed to the end wall 21 aof the suction housing 21. The second surface 45 bof the main body portion 45 is positioned to face the circuit board 41.As illustrated in FIG. 3, the holder 42 includes a tubular portion 46 provided upright from the first surface 45 aof the main body portion 45. The first surface 45 aof the main body portion 45 and an inner peripheral surface 46 aof the tubular portion 46 define an accommodation space 47.The tubular portion 46 according to the first embodiment is formed into an octagonal tubular shape. The tubular portion 46 includes a pair of first wall portions 461, a pair of second wall portions 462, and four third wall portions 463. The pair of first wall portions 461 are opposed to each other. The pair of second wall portions 462 oppose each other in a direction perpendicular to a direction in which the pair of first wall portions 461 oppose each other. Each of the third wall portions 463 connects the corresponding first wall portion 461 to the corresponding second wall portion 462.As illustrated in FIG. 1, in the first embodiment, an inverter circuit unit 43 is disposed between the main body portion 45 of the holder 42 and the end wall 21 aof the suction housing 21 in the axial direction of the rotation shaft 12. The inverter circuit unit 43 is mounted on the circuit board 41. The inverter circuit unit 43 converts a DC power into an AC power.As illustrated in FIG. 2, the inverter circuit unit 43 includes two connection lines EL 1 and EL 2. The inverter circuit 43 includes u-phase switching elements Qu 1 and Qu 2 corresponding to the u-phase coil 35 u. The inverter circuit 43 includes v-phase switching elements Qv 1 and Qv 2 corresponding to the v-phase coil 35 v. The inverter circuit unit 43 includes w-phase switching elements Qw 1 and Qw 2 corresponding to the w-phase coil 35 w. Each of the switching elements Qu 1 to Qw 2 is, for example, a power switching element such as an insulated gate bipolar transistor (IGBT). The switching elements Qu 1, Qu 2, Qv 1, Qv 2, Qw 1, and Qw 2 are connected to free wheeling diodes Du 1, Du 2, Dv 1, Dv 2, Dw 1, and Dw 2, respectively.The u-phase switching elements Qu 1 and Qu 2 are connected in series. A node between the u-phase switching elements Qu 1 and Qu 2 is connected to the u-phase coil 35 u. A series-connected body of the u-phase switching elements Qu 1 and Qu 2 is electrically connected to both connection lines EL 1 and EL 2.The v-phase switching elements Qv 1 and Qv 2 are connected in series. A node between the v-phase switching elements Qv 1 and Qv 2 is connected to the v-phase coil 35 v. A series-connected body of the v-phase switching elements Qv 1 and Qv 2 is electrically connected to both connection lines EL 1 and EL 2.The w-phase switching elements Qw 1 and Qw 2 are connected in series. A node between the w-phase switching elements Qw 1 and Qw 2 is connected to the w-phase coil 35 w. A series-connected body of the w-phase switching elements Qw 1 and Qw 2 is electrically connected to both connection lines EL 1 and EL 2.The control unit 44 controls the inverter circuit unit 43. the control unit 44 controls a switching operation of each of the switching elements Qu 1 to Qw 2. For example, the control unit 44 is formed of a dedicated hardware circuit or more and / or a processor (a control circuit) or more that operates according to computer programs (software). The processor includes a CPU and a memory such as a RAM and a ROM. The memory stores the program codes or instructions for causing the processor to perform various operations. The memory, i.e., a computer readable medium, includes any available medium that can be accessed by a general purpose computer or a dedicated computer.The control unit 44 is electrically connected to the air conditioner ECU 102 through the connector 16. The control unit 44 periodically turns on and off each of the switching elements Qu 1 to Qw 2 in response to commands from the air conditioner ECU 102. Specifically, the control unit 44 performs pulse width modulation (PWM) control of the switching elements Qu 1 to Qw 2 in response to the commands from the air conditioner ECU 102. More specifically, the control unit 44 generates control signals using a carrier signal (carrier wave signal) and command voltage signals (a signal to be compared). The control unit 44 performs ON / OFF control of each of the switching elements Qu 1 to Qw 2 using the generated control signals to convert DC powers into AC power.<Noise Reducing Unit>The noise reduction unit 50 is provided at an input side of the inverter circuit unit 43. The noise reducing unit 50 reduces common mode noise and differential mode noise.As illustrated in FIG. 1, in the first embodiment, the noise reduction unit 50 is disposed between the main body portion 45 of the holder 42 and the end wall 21 aof the suction housing 21 in the axial direction of the rotation shaft 21. The noise reduction unit 50 is mounted on the circuit board 41.As illustrated in FIG. 2, the noise reduction unit 50 includes a common mode choke coil 51 and a smoothing capacitor 52. the smoothing capacitor 52 forms a low pass filter circuit 53 together with the common mode choke coil 51. the low pass filter circuit 53 is provided at the connection lines EL 1 and EL 2. The low-pass filter circuit 53 is provided between the connector 16 and the associated circuit inverter circuit unit 43. The common mode choke coil 51 is provided at both connection lines EL 1 and E 2.The smoothing capacitor 52 is provided closer to the inverter circuit unit 43 than the common mode choke coil 51 for the related circuit. The smoothing capacitor 52 is an X capacitor connected in parallel to the inverter circuit unit 43. The smoothing capacitor 52 is electrically connected to both the connection lines EL 1 and EL 2. The common mode choke coil 51 and the smoothing capacitor 52 constitute an LC resonant circuit. Accordingly, the low-pass filter circuit 53 according to the first embodiment is the LC resonant circuit including the common mode choke coil 51.The noise reduction unit 50 has two Y capacitors 54. The two Y capacitors 54 are connected in series. A node between the two Y capacitors 54 is grounded to the body of the vehicle via the case 11. The two Y capacitors 54 are provided closer to the inverter circuit 43 than the common mode choke coil 51 for the related circuit. The two Y capacitors 54 are connected in parallel to the common mode choke coil 51. The two Y capacitors 54 are connected in parallel with the smoothing capacitor 52. That is, the two Y capacitors 54 are provided between the common mode choke coil 51 and the smoothing capacitor 52.The common mode choke coil 51 suppresses high frequency noise generated on a vehicle side from being transmitted to the inverter circuit unit 43 of the electric compressor 10. The common mode choke coil 51 reduces the common mode noise. A leakage inductance of the common mode choke coil 51 is used as an inductive component of the low pass filter (LC) circuits 53 for removing the differential mode noise (differential mode noise). That is, the common mode choke coil 51 serves to reduce the common mode noise and the differential mode noise (differential mode noise). Accordingly, in the electric compressor 10 according to the first embodiment, the common mode noise and the differential mode noise are reduced using the common mode choke coil 51 instead of using a choke coil for common mode and a choke coil for differential mode (differential mode).<Gleichtakt Reactor>As illustrated in FIG. 4, the common mode choke coil 51 includes a core 60, a first winding wire 61, and a second winding wire 62.The core 60 is formed in an annular shape. The core 60 is made of a ferromagnetic material, for example a ferrite core. The core 60 includes a first winding portion 601, a second winding portion 602, and a pair of connection portions 603. The first winding portion 601 and the second winding portion 602 each extend linearly. The first winding portion 601 and the second winding portion 602 extend parallel to each other. A connection portion 603 connects one end of the first winding portion 601 to one end of the second winding portion 602, and the other connection portion 603 connects the other end of the first winding portion 601 to the other end of the second winding portion 602. The core 60 has a first end surface 60 aand a second end surface 60 b. The first end surface 60 ais one end surface of the core 60 in an axial direction of the core 60, and the second end surface 60 bis the other end surface of the core 60 in the axial direction of the core 60.The first winding wire 61 is wound around the first winding portion 601 of the core 60. In the first embodiment, a part of the first winding wire 61 is also wound around the pair of connection portions 603 of the core 60. Both end portions of the first winding wire 601 are drawn from the core 60 across the first end surface 60 aof the core 60 as a pair of first lead portions 63.The second winding wire 62 is wound around the second winding portion 602 of the core 60. Also, in the first embodiment, a part of the second winding wire 62 is wound around the pair of connection portions 603 of the core 60. The second winding wire 62 is disposed adjacent to the first winding wire 61 at a distance. In the following description, a direction in which the first winding wire 61 and the second winding wire 62 are arranged is defined as a first direction, and a direction perpendicular to both the axial direction of the core 60 and the first direction is defined as a second direction. Both end portions of the second winding wire 62 are drawn from the core 60 across the first end surface 60 aof the core 60 as a pair of second lead portions 64.Each of the first winding wire 61 and the second winding wire 62 includes a first portion 65 positioned at the first end surface 60 aof the core 60, a second portion 66 positioned at the second end surface 60 bof the core 60, and a third portion 67 positioned at an outer peripheral surface 60 cof the core 60.As illustrated in FIGS. 5 at (a) and 6, the common mode choke coil 51 is accommodated in the accommodation space 47 of the holder 42. The axial direction of the core 60 and the axial direction of the tubular portion 46 are coincident with each other. The first end surface 60 aof the core 60 is positioned near the first surface 45 aof the main body portion 45. The second end surface 60 bof the core 60 is positioned near the end wall 21 aof the suction housing 21.As illustrated in FIG. 6, the first lead portions 63 and the second lead portions 64 are inserted into insertion holes 45 hthat extend through the main body portion 45. The first lead portions 63 and the second lead portions 64 are soldered to the circuit board 41, for example. As a result, the first winding wire 61 and the second winding wire 62 are electrically connected to the circuit board 41.<Magnet Material Damping Portion>As illustrated in FIGS. 3 and 5 (at (a), the noise reducing unit 50 includes a plurality of magnetic material attenuation portions 55 that reduce the differential-mode noise. The noise reduction unit 50 according to the first embodiment includes three magnetic material attenuation portions 55. In the first embodiment, the three magnetic material damping portions 55 have the same configuration. When the three magnetic material damping portions 55 are distinguished from each other, they are referred to as a first magnetic material damping portion 55 a, a second magnetic material damping portion 55 b, and a third magnetic material damping portion 55 c. The magnetic material damping portions 55 are each made of a plate-shaped conductive magnetic material. The magnetic material damping portions 55 are made of, for example, iron or electromagnetic steel. The magnetic material damping portions 55 are each formed in a plate shape. A thickness of each of the magnetic material damping portions 55 is several hundred micrometers. Here, in the drawing, the thickness of the magnetic material damping portion 55 is exaggerated.Each of the magnetic material damping portions 55 is disposed outside the tubular portion 46. The first magnetic material damping portion 55 ais provided along an outer circumferential surface 46 bof the tubular portion 46. The second magnetic material damping portion 55 bis provided along an outer peripheral surface of the first magnetic material damping portion 55 a. The third magnetic material damping portion 55 cis provided along an outer peripheral surface of the second magnetic material damping portion 55 b.The three magnetic material damping portions 55 are stacked in a direction perpendicular to the axial direction of the core 60.Each of the magnetic material damping portions 55 extends in a circumferential direction of the core 60 such that the magnetic material damping portion 55 surrounds an outer periphery of the core 60. Each of the magnetic material damping portions 55 includes a pair of first portions 551, a pair of second portions 552, and four third portions 553. The pair of first portions 551 are arranged with the common mode choke coil 51 interposed therebetween in the first direction. The pair of second portions 552 are arranged with the common mode choke coil 51 interposed therebetween in the second direction. The pair of second portions 552 include a pair of side portions 552 adisposed in a space between the first winding wire 61 and the second winding wire 62 disposed between the side portions 552 ain the second direction. Each of the third portions 553 connects the corresponding first portion 551 and the corresponding second portion 552.As illustrated in FIG. 5 at (b), each of the magnetic material damping portions 55 has a first surface 70 aand a second surface 70 b. The first surface 70 aand the second surface 70 bare surfaces of each of the magnetic material damping portions 55 that extend perpendicularly to a thickness direction of the magnetic material damping portion 55. The first surface 70 acorresponds to an inner peripheral surface of the magnetic material damping portion 55. the second surface 70 bcorresponds to an outer peripheral surface of the magnetic material damping portion 55. In the first embodiment, a first resin layer 71 is provided as a resin layer on the first surface 70 aof each of the magnetic material damping portions 55. A second resin layer 72 is provided as the resin layer on the second surface 70 bof each of the magnetic material damping portions 55. Note that illustration of the first resin layers 71 and the second resin layers 72 in FIGS. 3 and 5 is omitted at (a).The first magnetic material damping portion 55 aand the second magnetic material damping portion 55 bare insulated by the second resin layer 72 of the first magnetic material damping portion 55 aand the first resin layer 71 of the second magnetic material damping portion 55 b. That is, the second resin layer 72 of the first magnetic material damping portion 55 aand the first resin layer 71 of the second magnetic material damping portion 55 bform an insulation layer 73 disposed between the stacked magnetic material damping portions 55.The second magnetic material damping portion 55 band the third magnetic material damping portion 55 care insulated by the second resin layer 72 of the second magnetic material damping portion 55 band the first resin layer 71 of the third magnetic material damping portion 55 c. That is, the second resin layer 72 of the second magnetic material damping portion 55 band the first resin layer 71 of the third magnetic material damping portion 55 cform the insulation layer 73 disposed between the stacked magnetic material damping portions 55. Thus, the three magnetic material damping portions 55 are stacked with the insulating layer 73 interposed between the magnetic material damping portions 55.Each of the magnetic material damping portions 55 according to the first embodiment has gap portions G that increase magnetic reluctance in a direction in which the magnetic material damping portion 55 extends. In the first embodiment, the gap portions G are each formed in a corresponding one of the pair of side portions 552 a. Specifically, the gap portions G are formed on an imaginary straight line L extending in the second direction and positioned in a middle portion between the first winding wire 61 and the second winding wire 62 in the first direction. The gap portion G of the first magnetic material damping portion 55 a, the gap portion G of the second magnetic material damping portion 55 b, and the gap portion G of the third magnetic material damping portion 55 care aligned with each other in the second direction.In the first embodiment, the gap portion G is formed over an entire thickness of each of the magnetic material damping portions 55. In addition, the gap portion G is formed over an entire length of each of the magnetic material damping portions 55 in the axial direction of the core 60. With this configuration, each of the magnetic material damping portions 55 is interrupted in the direction in which the magnetic material damping portion 55 extends due to the gap portion G. Accordingly, portions of each of the magnetic material damping portions 55 positioned on opposite sides in the first direction across the imaginary straight line L are not electrically connected to each other.[Operation in First Embodiment]Next, an operation of the first embodiment will be described.The noise reduction unit 50 includes the magnetic material attenuation portions 55, each made of a plate-shaped magnetic material. In a state in which a push-pull current flows through the first winding wire 61 and the second winding wire 62, when the leakage magnetic flux leaking from the core 60 flows through the magnetic material damping portions 55, an eddy current is induced in each of the magnetic material damping portions 55. The eddy current induced in each of the magnetic material damping portions 55 is converted into thermal energy. This provides a damping effect.FIG. 7 is a graph showing a relationship between an input current input to the common mode choke coil 51 and an attenuation resistance in a comparative example 1, an example 1-1, and an example 1-2. As the damping resistance increases, the damping effect increases. In FIG. 7, a solid line represents the relationship in Comparative Example 1, a broken line represents the relationship in Example 1-1, and a long-short broken line represents the relationship in Example 1-2.Comparative Example 1, Example 1-1, and Example 1-2 are set under the same conditions except for the number of stacked magnetic material attenuation portions 55. In Comparative Example 1, the noise reducing unit 50 includes a magnetic material attenuation portion 55. That is, in Comparative Example 1, there is no stacked magnetic material attenuation portion 55. In Example 1-1, the noise reducing unit 50 includes two magnetic material attenuation portions 55 stacked with the insulation layer 73 interposed therebetween. In Example 1-2, the noise reducing unit 50 includes three magnetic material attenuation portions 55 stacked with the insulating layer 73 disposed between the magnetic material attenuation portions 55. That is, Example 1-2 corresponds to the first embodiment.As can be seen from FIG. 7, as the input current input to the common mode choke coil 51 increases, the attenuation resistance decreases. This tendency is common to Comparative Example 1, Example 1-1 and Example 1-2. However, the damping resistance in Example 1-1 and Example 1-2 decreases more gradually than that in Comparative Example 1. That is, as the number of the stacked magnetic material damping portions 55 increases, the damping resistance gradually decreases. In other words, as the number of stacked magnetic material attenuation portions 55 increases, the attenuation resistance tends not to decrease much even when the input current input to the common mode choke coil 51 increases. This is because as the number of the stacked magnetic material damping portions 55 increases, the magnetic material damping portions 55 hardly achieve magnetic saturation. Accordingly, in the first embodiment in which the plurality of magnetic material attenuation portions 55 having the insulation layers 73 are stacked between the magnetic material attenuation portions 55, attenuation resistance when a large current is input to the common mode choke coil 51 is easily secured.As illustrated in FIG. 7, when a small current is input to the common mode choke coil 51, the attenuation resistance in each of Example 1-1 and Example 1-2 is smaller than that in Comparative Example 1. Generally, an impedance at a higher frequency becomes larger in a characteristic of a coil. Accordingly, when a small current is input to the common mode choke coil 51, the attenuation resistance decreases as the number of the stacked magnetic material attenuation portions 55 increases.On the other hand, when a large current is input to the common mode choke coil 51, the attenuation resistance in Example 1-1 and Example 1-2 is larger than that in Comparative Example 1. A current value of the input current when the attenuation resistance is less than X in Example 1-1 and Example 1-2 is larger than that in Comparative Example 1.[Advantageous Effects According to First Embodiment]Advantageous effects according to the first embodiment will be described below.(1-1) In the first embodiment, three magnetic material attenuation portions 55 are stacked with the insulating layer 73 interposed between the magnetic material attenuation portions 55, so that the magnetic material attenuation portions 55 hardly achieve magnetic saturation. Accordingly, even when the input current input to the common mode choke coil 51 increases, the attenuation resistance does not tend to decrease much. Thus, the attenuation resistance when a large current is input to the common mode choke coil 51 is easily secured.Note that, in a case where only one magnetic material damping portion 55 having a large thickness is used instead of using the plurality of stacked magnetic material damping portions 55, due to a skin effect while an eddy current is induced on a surface of the magnetic material damping portion 55, the eddy current is difficultly induced inside the magnetic material damping portion 55. For this reason, even if the thickness of the only one magnetic material damping portion 55 is equal to the sum of the thicknesses of the plurality of stacked magnetic material damping portions 55, the damping effect obtained by the only one magnetic material damping portion 55 is smaller than that obtained by the plurality of stacked magnetic material damping portions 55 in the first embodiment. In other words, when the plurality of magnetic material damping portions 55 are stacked with the insulating layer 73 interposed between the magnetic material damping portions 55, as in the first embodiment, an eddy current is effectively induced in each of the magnetic material damping portions 55, so that a greater damping effect is obtained.(1-2) Each of the magnetic material damping portions 55 according to the first embodiment extends in the circumferential direction of the core 60 such that the magnetic material damping portion 55 surrounds the outer periphery of the core 60. In this case, a greater damping effect is obtained.(1-3) Each of the magnetic material damping portions 55 according to the first embodiment has the gap portions G that increase magnetic reluctance in the direction in which the magnetic material damping portion 55 extends. The leakage magnetic flux leaking from the core 60 flows more easily through a path in which the gap portion G is not formed than a path in which the gap portion G is formed in the magnetic material damping portions 55. Moreover, in the first embodiment, the gap portions G are respectively formed in the corresponding one of the pair of side portions 552 athat is disposed with the space between the first winding portion 61 and the second winding portion 62 that is disposed between the side portions 552 ain the second direction. With this configuration, as illustrated by the long-short dashed arrows in FIG. 5 at (a), the magnetic flux after passing through the first winding portion 601 of the core 60 and the magnetic flux after passing through the second winding portion 602 of the core 60 respectively flow through the magnetic material damping portions 55 without being interrupted by the gap portions G to show a loop.(1-4) The insulating layer 73 according to the first embodiment corresponds to the first resin layer 71 formed on the first surface 70 aand the second resin layer 72 formed on the second surface 70 bof each of the magnetic material damping portions 55. Thus, in comparison with a case where a gap is formed between the magnetic material damping portions 55 instead of the insulation layer 73, insulation between the magnetic material damping portions 55 is easily ensured.(1-5) The inverter device 15 according to the first embodiment includes the holder 42 made of a resin and having the main body portion 45 formed in the plate shape and the tubular portion 46 provided upright from the main body portion 54. The common mode choke coil 51 is accommodated in the accommodation space 47 defined by the main body portion 45 and the tubular portion 46 such that the axial direction of the core 60 coincides with the axial direction of the tubular portion 46. This makes it difficult for the common mode choke coil 51 to be shifted. The magnetic material damping portions 55 according to the first embodiment are disposed on the outer periphery of the tubular portion 46 of the holder 42. Accordingly, the magnetic material attenuation portions 55 are insulated from the common mode choke coil 51 of the tubular portion 46.[Second Embodiment]Next, a second embodiment of an electric compressor will be described with reference to FIGS. 8 to 11. Note that the second embodiment is different from the first embodiment mainly in that the electric compressor according to the second embodiment further includes a non-magnetic material damping portion. For this reason, detailed description of the same configurations as those according to the first embodiment will be omitted.< Magnetic Material Damping Portion>As illustrated in FIGS. 8 and 9 at (a), the noise reducing unit 50 includes a non-magnetic material attenuation portion 56 formed in a plate shape that reduces the differential-mode noise. The non-magnetic material damping portion 56 is made of a plate-shaped conductive non-magnetic material. The non-magnetic material damping portion 56 is made of, for example, copper or aluminum.The non-magnetic material damping portion 56 according to the second embodiment is formed in an annular shape. The non-magnetic material damping portion 56 includes a first cover portion 56 a, a second cover portion 56 b, a third cover portion 56 c, and a fourth cover portion 56 d. The first cover portion 56 a, the second cover portion 56 b, the third cover portion 56 c, and the fourth cover portion 56 dare each formed in a rectangular flat plate shape. The first cover portion 56 aand the second cover portion 56 bare parallel to each other. The second cover portion 56 bhas a through hole 56 h. The through hole 56 hextends through the second cover portion 56 bin a thickness direction thereof. The third cover portion 56 cconnects an end portion of the first cover portion 56 ain a longitudinal direction thereof to an end portion of the second cover portion 56 bin a longitudinal direction thereof. The fourth cover portion 56 dconnects the outer end portion of the first cover portion 56 ain the longitudinal direction thereof to the other end portion of the second cover portion 56 bin the associated longitudinal direction. The third cover portion 56 cand the fourth cover portion 56 dare parallel to each other.As illustrated in FIG. 9 at (a) and FIG. 10, the non-magnetic material attenuating portion 56 is accommodated in the accommodation space 47 of the holder 42 together with the common mode choke coil 51. A portion of the common mode choke coil 51 is disposed within the non-magnetic material attenuation portion 56. An axial direction of the non-magnetic material damping portion 56 coincides with the second direction. The first winding portion 601 and the second winding portion 602 of the core 60, a portion of the first winding wire 61 wound around the first winding portion 601 and a portion of the second winding wire 62 wound around the second winding portion 602 are positioned inside the non-magnetic material damping portion 56. The pair of connection portions 603 of the core 60, a pair of the first winding wire 61 wound around each of the connection portions 603, and a portion of the second winding wire 62 wound around each of the connection portions 603 are positioned outside the non-magnetic material damping portion 56. The pair of first lead portions 63 and the pair of second lead portions 64 are respectively positioned at opposite sides of the non-magnetic material damping portion 56 in the axial direction thereof.The first cover portion 56 aand the second cover portion 56 bare arranged with the common mode choke coil 51 interposed therebetween in the axial direction of the core 60. The first cover portion 56 ais positioned to be opposed to the first end surface 60 aof the core 60. The second cover portion 56 bis positioned to be opposed to the second end surface 60 bof the core 60. The first cover portion 56 acovers the first portion 65 of the first winding wire 61 and the first portion 65 of the second winding wire 62. the second cover portion 56 bcovers the second portion 66 of the first winding wire 61 and the second portion 66 of the second winding wire 62. the third cover portion 56 cand the fourth cover portion 56 dare arranged with the common mode choke coil 51 interposed therebetween in the first direction. The third cover portion 56 ccovers the third portion 67 of the first winding wire 61. the fourth cover portion 56 dcovers the third portion 67 of the second winding wire 62. as described above, the non-magnetic material attenuating portion 56 surrounds the first winding wire 61 and the second winding wire 62. the non-magnetic material attenuating portion 56 covers the first portions 65, the second portions 66, and the third portions 67 of the first winding wire 61 and the second winding wire 62.As illustrated in FIG. 10, a surface opposite to the other surface of the first cover portion 56 aopposing the common mode choke coil 51 is opposed to the first surface 45 aof the main body portion 45 of the holder 42. A heat dissipation lubricant, which is not illustrated, is applied between a surface opposite to the other surface of the second cover portion 56 b, which is opposite to the common mode choke coil 51, and another surface of the end wall 21 aof the exhaust housing 21. A surface opposite to the other surface of the third cover portion 56 copposing the common mode choke coil 51 and a surface opposite to the other surface of the fourth cover portion 56 dopposing the common mode choke coil 51 are respectively opposed to corresponding ones of inner surfaces of the pair of first wall portions 461 of the tubular portion 46.As illustrated in FIG. 9 at (a) and at (b), the three magnetic material damping portions 55 are arranged with the insulating layer 73 interposed between the magnetic material damping portions 55. Similarly to the first embodiment, the illustrations of the insulation layers 73 in FIG. 9 are omitted at (a).The plurality of magnetic material attenuation portions 55 are disposed outside the first winding wire 61 and the second winding wire 62 of the common mode choke coil 51 via the non-magnetic material attenuation portion 56. In the second embodiment, the first portion 551 of each of the magnetic material damping portions 55 is disposed on a corresponding side in the first direction opposite to the first winding wire 61 and the second winding wire 62 via the third cover portion 56 cof the non-magnetic material damping portion 56. The first portion 551 of each of the magnetic material damping portions 55 on the other side thereof in the first direction is disposed opposite to the first winding wire 61 and the second winding wire 62 via the fourth cover portion 56 dof the non-magnetic material damping portion 56.[Operation in the Second Embodiment]Next, an operation according to the second embodiment will be described.The noise reduction unit 50 includes the non-magnetic material attenuation portion 56 made of the plate-shaped non-magnetic material. The non-magnetic material damping portion 56 surrounds the first winding wire 61 and the second winding wire 62, and accordingly, an induced current that generates a magnetic flux opposing a change in the leakage magnetic flux leaking from the core 60 flows through the non-magnetic material damping portion 56. This also provides a damping effect.FIG. 11 is a graph showing a relationship between an input current input to the common mode choke coil 51 and an attenuation resistance in a comparative example 2- 1, a comparative example 2- 2, an example 2- 1, and an example 2- 2. In FIG. 11, a long double-short dashed line represents the relationship in Comparative Example 2- 1, a solid line represents the relationship in Comparative Example 2- 2, a dashed line represents the relationship in Example 2- 1, and a long-short dashed line represents the relationship in Example 2- 2.Comparative Example 2- 1, Comparative Example 2- 2, Example 2- 1, and Example 2- 2 are set under the same conditions except for the number of the stacked magnetic material damping portions 55. In Comparative Example 2- 1, Comparative Example 2- 2, Example 2- 1, and Example 2- 2, the noise reducing unit 50 includes the non-magnetic material damping portion 56. In Comparative Example 2-1, the noise reducing unit 50 does not include the magnetic material attenuation portion 55. In Comparative Example 2-2, the noise reducing unit 50 includes a magnetic material attenuation portion 55. That is, in Comparative Example 2- 1 and Comparative Example 2- 2, there is no stacked magnetic material attenuation portion 55. In Example 2- 1, the noise reducing unit 50 includes two magnetic material attenuation portions 55 stacked with the insulating layer 73 interposed therebetween. In Example 2-2, the noise reducing unit 50 includes three magnetic material attenuation portions 55 stacked with the insulating layer 73 interposed between the magnetic material attenuation portions 55. That is, Example 2-2 corresponds to the second embodiment.As is apparent from FIG. 11, the damping resistance in Comparative Example 2-2, Example 2-1, and Example 2-2 is larger than that in Comparative Example 2-1. That is, the damping resistance increases in a case where the noise reducing unit 50 includes both the magnetic material damping portion 55 and the non-magnetic material damping portion 56, compared with a case where the noise reducing unit 50 includes only the non-magnetic material damping portion 56.The damping resistance in Example 2-1 and Example 2-2 decreases more gradually than that in Comparative Example 2-2. That is, similarly to the first embodiment, as the number of the magnetic material damping portions 55 increases, the damping resistance decreases more gradually. In other words, as the number of the stacked magnetic material attenuation portions 55 increases, the attenuation resistance tends not to decrease much even when the input current input to the common mode choke coil 51 increases. Accordingly, in the second embodiment in which the plurality of magnetic material attenuation portions 55 are stacked with the insulation layers 73 interposed between the magnetic material attenuation portions 55, attenuation resistance when a large current is input to the common mode choke coil 51 is easily secured.In addition, regardless of the magnitude of the input current, the attenuation resistance in Example 2-1 and Example 2-2 is larger than that in Comparative Example 2-2. In addition, regardless of the magnitude of the input current, the attenuation resistance in Example 2-2 is larger than that in Example 2-1. That is, unlike the first embodiment, in a case where the noise reducing unit 50 includes the non-magnetic material damping portion 56, the damping resistance increases as the number of the magnetic material damping portions 55 increases. This is because the leakage magnetic flux leaking from the core 60 increases as the number of the magnetic material damping portions 55 increases, which increases the induced current flowing through the non-magnetic material damping portion 56. Accordingly, in the second embodiment in which the noise reducing unit 50 includes the non-magnetic material attenuating portion 56, the attenuation resistance increases when a small current is input to the common mode choke coil 51.[Advantageous Effects of Second Embodiment]Advantageous effects according to the second embodiment will be described below. The second embodiment provides the below-mentioned advantageous effects in addition to the advantageous effects (1-1) to (1-5) according to the first embodiment.(2-1) The noise reduction unit 50 according to the second embodiment includes the non-magnetic material attenuation portion 56 made of a non-magnetic material. With this configuration, an induced current that generates a magnetic flux that counteracts a change in the leakage magnetic flux leaking from the core 60 flows through the non-magnetic material damping portion 56. This also provides a damping effect.Further, the noise reducing unit 50 includes the plurality of magnetic material attenuation portions 55. With this configuration, the leakage magnetic flux increases compared with the case where the noise reducing unit 50 includes a magnetic material damping portion 55, which increases the induced current flowing through the non-magnetic material damping portion 56. Accordingly, when a small current is input to the common mode choke coil 51, the attenuation resistance increases.(2-2) For example, when the magnetic material damping portions 55 are disposed between the first winding wire 61 and the non-magnetic material damping portion 56 and between the second winding wire 62 and the non-magnetic material damping portion 56, the leakage magnetic flux leaking from the core 60 branches into a leakage magnetic flux flowing through the magnetic material damping portions 55 inside the non-magnetic material damping portion 56 to show a loop and a leakage magnetic flux flowing through an outside of the non-magnetic material damping portion 56 to show a loop. Then, due to a magnetic flux flowing through the magnetic material damping portions 55, the leakage magnetic flux flowing through a cross section of the through hole 56 hof the non-magnetic material damping portion 56 decreases, so that the induced current flowing through the non-magnetic material damping portion 56 decreases. As a result, the damping effect obtained from the non-magnetic material damping portion 56 decreases.On the other hand, in the second embodiment, the plurality of magnetic material attenuation portions 55 are disposed outside the first winding wire 61 and the second winding wire 62 via the non-magnetic material attenuation portion 56. In this case, the leakage magnetic flux passing through the cross section of the through hole 56 hof the non-magnetic material damping portion 56 does not decrease due to the leakage magnetic flux flowing through the magnetic material damping portions 55, so that the induced current flowing through the non-magnetic material damping portion 56 does not decrease. Accordingly, the damping effect obtained from the non-magnetic material damping portion 56 is prevented from decreasing.(2-3) The non-magnetic material attenuating portion 56 is accommodated in the accommodation space 47 of the holder 42 together with the common mode choke coil 51. This makes it difficult for the non-magnetic material damping portion 56 to be displaced. The magnetic material damping portions 55 according to the second embodiment are disposed on the outer periphery of the tubular portion 46 of the holder 42. Thus, the tubular portion 46 isolates the magnetic material attenuation portions 55 not only in front of the common mode choke coil 51 but also in front of the non-magnetic material attenuation portion 56.<>The above-described embodiments may be modified as described below. The above-described embodiments and the modifications mentioned below may be combined with each other as long as they do not technically contradict each other.The inverter device 15 does not need to have a holding device 42.The tubular portion 46 of the holder 42 does not need to be formed in the octagonal tubular shape as long as the tubular portion 46 is formed in a tubular shape.The number of magnetic material damping portions 55 stacked with the insulating layer 73 interposed between the magnetic material damping portions 55 is not limited to three. The number of the magnetic material damping portions 55 stacked with the insulating layer 73 interposed between the magnetic material damping portions 55 may be two or four or more.When an eddy current is generated in each of the magnetic material attenuation portions 55 by the leakage magnetic flux leaking from the core 60, a shape of each of the magnetic material attenuation portions 55, as well as positions of the magnetic material attenuation portions 55 with respect to the common mode choke coil 51, can be changed as appropriate. Here, the plurality of magnetic material attenuation portions 55 need to be stacked with the insulation layer 73 interposed between the magnetic material attenuation portions 55.Each of the magnetic material damping portions 55 may be formed in a flat plate shape, an L shape, or a U shape, for example.For example, the magnetic material attenuation portions 55 may be arranged so as to cover only the third portion 67 of the first winding wire 61, or may be arranged with the common mode choke coil 51 interposed therebetween in the axial direction of the core 60.The shape of each of the magnetic material attenuation portions 55 and the positions of the magnetic material attenuation portions 55 with respect to the common mode choke coil 51 need not be the same for all the magnetic material attenuation portions 55. The shape of each of the magnetic material attenuation portions 55 and the positions of the magnetic material attenuation portions 55 with respect to the common mode choke coil 51 may be different for each of the magnetic material attenuation portions 55. Here, the plurality of magnetic material damping portions 55 need to be stacked with the insulating layer 73 interposed between the magnetic material damping portions 55. The entire portion of one magnetic material damping portion 55 and a portion of another magnetic material damping portion 55 may be stacked with the insulating layer 73 interposed therebetween, or a portion of one magnetic material damping portion 55 and a portion of another magnetic material damping portion 55 may be stacked with the insulating layer 73 interposed therebetween.In the above-described embodiments, the insulation layer 73 corresponds to the first resin layer 71 provided on the first surface 70 aof each of the magnetic material damping portions 55 and the second resin layer 72 provided on the second surface 70 bof each of the magnetic material damping portions 55; however, the present invention is not limited thereto. Any element may be used as the insulating layer 73 as long as the element is disposed between the magnetic material damping portions 55 to insulate them.As an example, instead of the insulating layer 73, a space may be formed between the magnetic material damping portions 55.As another example, instead of the insulating layer 73, a member having an insulating property and provided separately from the magnetic material damping portions 55 may be formed between the magnetic material damping portions 55.In the above-described embodiments, the resin layers are provided on the opposite surfaces of each of the magnetic material damping portions 55; however, the resin layer may be provided on only one side of each of the magnetic material damping portions 55.For example, the first resin layer 71 may be provided on the first surface 70 aof each of the magnetic material damping portions 55, and the second resin layer 72 may not be provided on the second surface 70 bof each of the magnetic material damping portions 55. In this case, the insulation layer 73 is formed of only the first resin layer 71.For example, the second resin layer 72 may be provided on the second surface 70 bof each of the magnetic material damping portions 55, and the first resin layer 71 may not be provided on the first surface 70 aof each of the magnetic material damping portions 55. In this case, the insulation layer 73 is formed of only the second resin layer 72.In the above-described embodiments, the gap portions G are formed in all of the three magnetic material damping portions 55. However, the present invention is not limited thereto.The gap portion G may be formed in at least one of the magnetic material damping portions 55 stacked with the insulation layer 73 interposed between the magnetic material damping portions 55. The term "at least one" used in the present specification means "one or more" of the desired options. As an example, the phrase "at least one" used in the present specification means, when there are two options, "only one option", or "both of the two options". As another example, the phrase "at least one" used in the present specification means, when there are three or more options, "only one of the options", or "any combination of two options or more".The gap portions G need not be formed in all of the magnetic material damping portions 55 stacked with the insulation layer 73 interposed between the magnetic material damping portions 55.In the above-described embodiments, the gap portions G are formed at both of the pair of side portions 552 ain each of the magnetic material damping portions 55; however, the gap portions G may be formed at only one of the side portions 552 a. As long as the gap portions G are formed in at least one of the pair of side portions 552 a, the effect (1- 3) according to the first embodiment is obtained. Note that "at least one of the pair of side portions 552 a" means "only one of the side portions 552 a", "only the other of the side portions 552 a", or "both of the side portions 552 a".In the above-described embodiments, the gap portions G are formed on the imaginary straight line L; however, the gap portions G may be positioned at a position shifted from the imaginary straight line L in the first direction.In the above-described embodiments, the gap portions G are formed in the side portions 552 aof each of the magnetic material damping portions 55; however, the gap portions G may be formed in the first portions 551 or the third portions 553 other than the side portions 552 aof the second portions 552.The positions of the gap portions G of the magnetic material damping portions 55 need not be the same for all of the magnetic material damping portions 55. The positions of the gap portions G of the magnetic material damping portions 55 may be different for each of the magnetic material damping portions 55, for example.In the above-described embodiments, the gap portions G are each formed over the entire thickness of the corresponding magnetic material damping portion 55, but the present invention is not limited thereto. The gap portions G may each be formed in a portion of the corresponding magnetic material damping portion 55 in the thickness direction thereof.In the above-described embodiments, the gap portions G are each formed over the entire length of the corresponding magnetic material damping portion 55 in the axial direction of the core 60, but the present invention is not limited thereto. The gap portions G may be formed in a portion of the corresponding magnetic material damping portion 55 in the axial direction of the core 60.The plurality of magnetic material damping portions 55 may be disposed within the tubular portion 46. In this case, the insulation between the magnetic material attenuation portions 55 and the common mode choke coil 51 needs to be secured. Examples of methods for securing insulation include a method for securing an insulation distance between the magnetic material attenuation portion 55 and the common mode choke coil 51, and a method for performing insulation treatment on the surface of the magnetic material attenuation portion 55 that faces the common mode choke coil 51. In the case where the magnetic material attenuation portions 55 are disposed inside the tubular portion 46 in the second embodiment, insulation between the magnetic material attenuation portions 55 and the non-magnetic material attenuation portion 56 needs to be secured in addition to insulation between the magnetic material attenuation portions 55 and the common mode choke coil 51.In this case, insulation between the magnetic material damping portions 55 and the other electronic components mounted on the circuit board 41 and positioned outside the tubular portion 46 is ensured by the tubular portion 46. Further, as compared with the case where the magnetic material damping portions 55 are disposed outside the tubular portion 46, the magnetic material damping portions 55 are formed closer to the core 60, so that a greater damping effect is obtained.All magnetic material damping portions 55 need not be disposed outside or inside the tubular portion 46.For example, one of two magnetic material damping portions 55 may be disposed outside the tubular portion 46, and the other of the two magnetic material damping portions 55 may be disposed inside the tubular portion 46. In this case, the tubular portion 46 serves as the insulating layer 73 that insulates the one of the magnetic material damping portions 55 from the other of the magnetic material damping portions 55.As long as the core 60 is formed in an annular shape, the shape of the core 60 may be changed as appropriate. The core 60 may be formed in a circular ring shape, for example.In the above-described embodiments, the core 60 is formed of one part; however, the core 60 may be formed of two parts or more.As long as the non-magnetic material attenuating portion 56 surrounds the first winding wire 61 and the second winding wire 62, the shape of the non-magnetic material attenuating portion 56 may be changed as appropriate. The non-magnetic material damping portion 56 may be formed in a circular ring shape, for example.In the above-described embodiments, the non-magnetic material damping portion 56 may be formed of one piece; however, the non-magnetic material damping portion 56 may be formed of two pieces or more.The noise reduction unit 50 may include a plurality of common mode choke coils 51. In the second embodiment, the noise reducing unit 50 may include the non-magnetic material attenuating portion 56 having the same number as that of the common mode choke coil 51.The compacting part 13 is not limited to a screw type compacting part. For example, the compressing part 13 may be a piston type compressing part or an impeller type compressing part.The electric compressor 10 may be mounted on a fuel cell vehicle. In this case, the electric compressor 10 may be an electric compressor in which air as fluid supplied to a fuel cell is compressed by the compression part 13.[Additional Notes]Technical ideas obtained from the above-described embodiments and the modifications will be described below.< Note1>An electric compressor comprising:a compressing part configured to compress a fluid;a motor configured to drive the compression part;an inverter device configured to drive the motor,wherein the inverter device comprises:an inverter circuit unit that converts a DC power into an AC power; anda noise reducing unit provided on an input side of the inverter circuit unit and reducing common mode noise and differential mode noise, whereinthe noise reducing unit includes:a common mode choke coil having a core formed in an annular shape, a first winding wire wound around the core, and a second winding wire wound around the core and disposed adjacent to the first winding wire at a distance, wherein the common mode choke coil reduces common mode noise;a smoothing capacitor forming a low pass filter circuit together with the common mode choke coil; anda magnetic material attenuation portion made of a plate-shaped magnetic material and into which an eddy current is induced by a leakage magnetic flux leaking from the core, the magnetic material attenuation portion reducing the push-pull noise, characterized in thatthe noise reducing unit includes a plurality of the magnetic material attenuation portions, andstacking the plurality of magnetic material damping portions with an insulating layer disposed between the magnetic material damping portions.< Note 2>The electric compressor according to Supplementary Note 1, characterized in that the plurality of magnetic material damping portions each extend in a circumferential direction of the core such that the magnetic material damping portion surrounds an outer periphery of the core.< Note 3>The electric compressor according to Supplementary Note 1, characterized in that the noise reducing unit includes a non-magnetic material attenuation portion made of a plate-shaped non-magnetic material and arranged such that the non-magnetic material attenuation portion surrounds the first winding wire and the second winding wire and through which an induced current flows, the non-magnetic material attenuation portion reduces the differential-mode noise, the induced current generates a magnetic flux that counteracts a change in the leakage magnetic flux leaking from the core, and the plurality of magnetic material attenuation portions are respectively arranged outside the first winding wire and the second winding wire via the non-magnetic material attenuation portion, the magnetic material attenuation portion extending in a circumferential direction of the core such that, the magnetic material damping portion surrounds an outer periphery of the core.< Note 4>The electric compressor according to Supplementary Note 2 or 3, characterized in that a direction in which the first winding wire and the second winding wire are arranged is defined as a first direction and a direction perpendicular to both an axial direction of the core and the first direction is defined as a second direction, the plurality of magnetic material damping portions each include a pair of side portions arranged with a space between the first winding wire and the second winding wire arranged between the side portions in the second direction, and at least one of the plurality of magnetic material damping portions has a gap portion in at least one of the side portions, the gap portion increasing magnetic reluctance in a direction in which the magnetic material damping portion extends.< Note 5>The electric compressor according to any one of Supplementary Notes 1 to 4, characterized in that the insulation layer is a resin layer provided on a surface of each of the magnetic material damping portions.References included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedJP 6 673 468 B2

[0002]

Claims

An electric compressor (10) comprising: a compressing part (13) configured to compress a fluid; a motor (14) configured to drive the compressing part (13); an inverter device (15) configured to drive the motor (14), the inverter device (15) comprising: an inverter circuit unit (43) that converts a DC power into an AC power; A noise reducing unit (50) provided on an input side of the inverter circuit unit (43) and reducing common mode noise and differential mode noise, the noise reducing unit (50) comprising: a common mode choke coil (51) comprising a core (60) formed in an annular shape, a first winding wire (61) wound around the core (60), and a second winding wire (62) wound around the core (60) and disposed adjacent to the first winding wire (61) at a distance, the common mode choke coil (51) reducing the common mode noise; a smoothing capacitor (52) forming a low pass filter circuit together with the common mode choke coil (51); and a magnetic material attenuation portion (55) made of a plate-shaped magnetic material and in which an eddy current is induced by a leakage magnetic flux leaking from the core (60), the magnetic material attenuation portion (55) reducing the push-pull noise, characterized in that the noise reduction unit (50) includes a plurality of the magnetic material attenuation portions (55), and the plurality of magnetic material attenuation portions (55) are stacked with an insulation layer (73) disposed between the magnetic material attenuation portions (55).The electric compressor (10) according to claim 1, characterized in that the plurality of magnetic material damping portions (55) each extend in a circumferential direction of the core (60) such that the magnetic material damping portion (55) surrounds an outer periphery of the core (60).The electric compressor (10) according to claim 1, characterized in that the noise reducing unit (50) includes a non-magnetic material attenuation portion (56) made of a plate-shaped non-magnetic material and arranged such that the non-magnetic material attenuation portion (56) surrounds the first winding wire (61) and the second winding wire (62) and through which an induced current flows, the non-magnetic material attenuation portion (56) reduces the push-pull noise, the induced current generates a magnetic flux that counteracts a change in the leakage magnetic flux leaking from the core (60), and the plurality of magnetic material attenuation portions (55) are respectively arranged outside the first winding wire (61) and the second winding wire (62) via the non-magnetic material attenuation portion (56), wherein the magnetic material damping portion (55) extends in a circumferential direction of the core (60) such that the magnetic material damping portion (55) surrounds an outer periphery of the core (60).The electric compressor (10) according to claim 2 or 3, characterized in that a direction in which the first winding wire (61) and the second winding wire (62) are arranged is defined as a first direction and a direction perpendicular to both an axial direction of the core (60) and the first direction is defined as a second direction, the plurality of magnetic material damping portions (55) each include a pair of side portions (552a) arranged with a space between the first winding wire (61) and the second winding wire (62) arranged between the side portions (552a) in the second direction, and at least one of the plurality of magnetic material damping portions (55) has a gap portion (G) in at least one of the side portions (552a), wherein the gap portion (G) increases a magnetic reluctance in a direction in which the magnetic material damping portion (55) extends.The electric compressor (10) according to any one of claims 1 to 4, characterized in that the insulation layer (73) is a resin layer provided on a surface of each of the magnetic material damping portions (55).

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