Capacitor device and power converter

Abstract

This invention provides a capacitor device that suppresses the influence of electromagnetic noise generated by smoothing capacitors on other components. [Solution] The capacitor module 50, as a capacitor device, comprises a capacitor element 53 and a shielding member 57. The capacitor element 53 is connected to a semiconductor element that performs switching operation to convert power and is an element that smooths voltage fluctuations. The shielding member 57 is positioned opposite the capacitor element 53 and is a member that absorbs electromagnetic noise EN generated by the alternating current flowing between the electrodes of the capacitor element 53. The shielding member 57 is connected to a member that is at ground potential.

Description

Technical Field

[0001] The disclosure in this specification relates to a capacitor device having a smoothing capacitor and a power conversion device.

Background Art

[0002] Patent Document 1 describes a first electronic device as a noise source, a second electronic device susceptible to the influence of noise, and a capacitor disposed between these electronic devices. By providing an electromagnetic shield for the capacitor, it is possible to suppress the second electronic device from being affected by the noise generated in the first electronic device.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in a power conversion device including a semiconductor element that performs a switching operation to convert power and a smoothing capacitor that smooths voltage fluctuations accompanying the switching operation, not only the semiconductor element but also the smoothing capacitor becomes a noise source. That is, electromagnetic noise is generated by the alternating current flowing between the electrodes of the smoothing capacitor. In particular, in recent years, the switching speed has become high, and as a result, the electromagnetic noise generated by the smoothing capacitor has become so large that it cannot be ignored.

[0005] One disclosed object is to provide a capacitor device and a power conversion device that suppress the electromagnetic noise generated by the smoothing capacitor from affecting other components.

Means for Solving the Problems

[0006] To achieve the above objective, the "capacitor device" described herein is: A capacitor element (53) is connected to a semiconductor element (33) that performs switching operation to convert power, A shielding member (57) is positioned opposite the capacitor element and absorbs electromagnetic noise generated by the alternating current flowing between the electrodes of the capacitor element, Equipped with, The shielding member is connected to the member that is at ground potential.

[0007] The capacitor device disclosed herein includes a shielding member positioned opposite the capacitor element, and the shielding member is connected to a member that is at ground potential. Therefore, electromagnetic noise radiated from the capacitor element is absorbed by the shielding member and its radiation to the outside of the capacitor device is suppressed.

[0008] The "power conversion device" disclosed herein is A semiconductor module (30) that performs switching operation to convert power, A capacitor element (53) connected to the semiconductor module, A shielding member (57) is positioned opposite the capacitor element and absorbs electromagnetic noise generated by the alternating current flowing between the electrodes of the capacitor element, Equipped with, The shielding member is connected to the member that is at ground potential.

[0009] The power conversion device disclosed herein includes a shielding member positioned opposite the capacitor element, and the shielding member is connected to a member that is at ground potential. Therefore, electromagnetic noise radiated from the capacitor element is absorbed by the shielding member and its radiation to the outside of the power conversion device is suppressed.

[0010] The reference numbers in parentheses above are merely examples of correspondences with specific configurations in the embodiments described later, and do not limit the technical scope in any way. [Brief explanation of the drawing]

[0011] [Figure 1] This figure shows the circuit configuration and drive system in a power conversion device according to the first embodiment. [Figure 2] This is a cross-sectional view of a power conversion device according to the first embodiment. [Figure 3] This is a schematic cross-sectional view showing the portion of the capacitor module according to the first embodiment that is near the busbar. [Figure 4] This is a schematic cross-sectional view showing the portion of the capacitor module according to the first embodiment that is near the shielding member. [Figure 5] This is a schematic perspective view showing a capacitor module according to the first embodiment. [Figure 6] This is a schematic diagram showing the ground connection state between the power converter and the vehicle frame according to the first embodiment. [Figure 7] This is a schematic top view showing a power conversion device according to the second embodiment. [Figure 8] This is a schematic top view showing a power conversion device according to the third embodiment. [Figure 9] This is a schematic top view showing a power conversion device according to the fourth embodiment. [Figure 10] This is a schematic top view showing a power conversion device according to the fifth embodiment. [Figure 11] This is a schematic top view showing a power conversion device according to the sixth embodiment. [Modes for carrying out the invention]

[0012] Hereinafter, a plurality of embodiments will be described based on the drawings. In each embodiment, corresponding components may be denoted by the same reference numerals, and redundant descriptions may be omitted. When only a part of the configuration is described in each embodiment, the configuration of other embodiments described previously can be applied to other parts of the configuration. In addition, not only the combinations of configurations explicitly shown in the description of each embodiment, but also the configurations of a plurality of embodiments can be partially combined with each other as long as there is no problem with the combination.

[0013] The electric device of this embodiment is, for example, a power conversion device applied to a moving body having a rotating electric machine as a drive source. The moving body is, for example, an electric vehicle (BEV), a hybrid vehicle (HEV), a plug-in hybrid vehicle (PHEV), or other electric vehicles, an electric flying body such as a drone or an electric vertical take-off and landing aircraft (eVTOL), a ship, a construction machine, or an agricultural machine. Hereinafter, an example applied to a vehicle will be described.

[0014] (First Embodiment) First, based on FIG. 1, the schematic configuration of the vehicle drive system will be described. As shown in FIG. 1, the vehicle drive system 1 includes a DC power source 2, a motor 3, and a power conversion device 4.

[0015] The DC power source 2 is a DC voltage source composed of a rechargeable secondary battery. The motor 3 is a three-phase AC rotating electric machine. The motor 3 functions as a driving source for the vehicle, that is, an electric motor. The motor 3 functions as a generator during regeneration. The power conversion device 4 is an inverter 5 that performs power conversion between the DC power source 2 and the motor 3. The power conversion device 4 may further include a smoothing capacitor 6, a drive circuit 7, and the like.

[0016] The smoothing capacitor 6 primarily smooths the DC voltage supplied from the DC power supply 2. The smoothing capacitor 6 is connected to the P line 8, which is the high-potential power line, and the N line 9, which is the low-potential power line. The P line 8 is connected to the positive terminal of the DC power supply 2, and the N line 9 is connected to the negative terminal of the DC power supply 2. The positive terminal of the smoothing capacitor 6 is connected to the P line 8 between the DC power supply 2 and the inverter 5. The negative terminal of the smoothing capacitor 6 is connected to the N line 9 between the DC power supply 2 and the inverter 5. The smoothing capacitor 6 is connected in parallel to the DC power supply 2.

[0017] Inverter 5 is a DC-AC conversion circuit. Inverter 5 converts a DC voltage to a three-phase AC voltage according to switching control by a control circuit (not shown) and outputs it to the motor 3. This drives the motor 3 to generate a predetermined torque. During regenerative braking of the vehicle, inverter 5 converts the three-phase AC voltage generated by the motor 3 in response to the rotational force from the wheels to a DC voltage according to switching control by the control circuit and outputs it to the P line 8. In this way, inverter 5 performs bidirectional power conversion between the DC power supply 2 and the motor 3.

[0018] The inverter 5 is configured with three phase upper and lower arm circuits 10. The upper and lower arm circuits 10 are sometimes referred to as legs. The upper and lower arm circuits 10 each have an upper arm 10H and a lower arm 10L. The upper arm 10H and the lower arm 10L are connected in series between the P line 8 and the N line 9, with the upper arm 10H on the P line 8 side.

[0019] The connection point between the upper arm 10H and the lower arm 10L, i.e., the midpoint of the upper and lower arm circuits 10, is connected to the corresponding phase winding 3a of the motor 3 via the output line 11. Of the upper and lower arm circuits 10, the U-phase upper and lower arm circuit 10U is connected to the U-phase winding 3a via the output line 11. The V-phase upper and lower arm circuit 10V is connected to the V-phase winding 3a via the output line 11. The W-phase upper and lower arm circuit 10W is connected to the W-phase winding 3a via the output line 11.

[0020] The upper and lower arm circuit 10 (10U, 10V, 10W) ​​has a series circuit 12. The series circuit 12 is configured by connecting the switching element on the upper arm 10H side and the switching element on the lower arm 10L side in series between the P line 8 and the N line 9. In this embodiment, n-channel type MOSFETs 13 are used as each switching element. MOSFET is an abbreviation for Metal Oxide Semiconductor Field Effect Transistor. Each of the MOSFETs 13 has a freewheeling diode 14 (hereinafter referred to as FWD14) connected in antiparallel.

[0021] In the upper arm 10H, the drain of MOSFET 13 is connected to the P line 8. In the lower arm 10L, the source of MOSFET 13 is connected to the N line 9. The drain of MOSFET 13 in the upper arm 10H and the drain of MOSFET 13 in the lower arm 10L are interconnected. Note that the switching element is not limited to MOSFET 13. For example, an IGBT may be used. IGBT is an abbreviation for Insulated Gate Bipolar Transistor.

[0022] The drive circuit 7 drives the switching elements that make up the power conversion circuit, such as the inverter 5. Based on the drive command from the control circuit, the drive circuit 7 supplies a drive voltage to the gate of the corresponding MOSFET 13. By applying the drive voltage, the drive circuit drives the corresponding MOSFET 13, i.e., turns it on or off. The drive circuit is sometimes referred to as a driver.

[0023] The power converter 4 may include a control circuit for the switching element. The control circuit generates a drive command to operate the MOSFET 13 and outputs it to the drive circuit 7. The control circuit generates the drive command based on, for example, a torque request input from a higher-level ECU (not shown) and signals detected by various sensors. ECU is an abbreviation for Electronic Control Unit. The control circuit may be located within the higher-level ECU.

[0024] As shown in Figure 2, the power converter 4 includes a base 20 with a first cooler 21, a semiconductor module 30, a second cooler 40, a capacitor module 50, a circuit board 60, and a board stay 70, etc. In the following description, the direction in which the multiple semiconductor modules 30 are arranged is referred to as the X direction. The Z direction is perpendicular to the X direction and is the stacking direction of the first cooler 21, the semiconductor modules 30, and the second cooler 40. The Y direction is perpendicular to both the X and Z directions. The X, Y, and Z directions are in a positional relationship that is orthogonal to each other.

[0025] The base 20 has a semiconductor module 30 mounted on one of its surfaces 20a. The base 20 is a support member that supports the semiconductor module 30. In this embodiment, as an example, the semiconductor module 30 and the capacitor module 50 are arranged on one surface of the base 20. The base 20 is formed using a metallic material such as aluminum.

[0026] The base 20 has a first cooler 21. The first cooler 21 is constructed using the base 20. The first cooler 21 is constructed with a flow path 211 formed inside the base 20 and a portion of the base 20 surrounding the flow path 211. A coolant 212 flows through the flow path 211. The first cooler 21 cools the semiconductor module 30 from the bottom side. The base 20 may be provided as a standalone unit or as part of a case that houses other elements of the power converter 4.

[0027] As an example, the base 20 of this embodiment is provided as the bottom wall of the case 22. The case 22 has an opening to accommodate other elements. The case 22 has a base 20 that forms the bottom wall and a side wall 23 that is connected to the base 20 and together with the base 20 defines the housing space. The housing space of the case 22 contains a semiconductor module 30, a second cooler 40, a capacitor module 50, a circuit board 60, and the like. The power converter 4 may also have a cover (lid) (not shown) that closes the opening of the case 22. The case 22 and the cover are sometimes referred to as a housing.

[0028] The semiconductor module 30 constitutes the upper and lower arm circuit 10 described above, i.e., the inverter 5. The power converter 4 of this embodiment includes three semiconductor modules 30. One semiconductor module 30 provides one series circuit 12, i.e., one phase of the upper and lower arm circuit 10. The multiple semiconductor modules 30 include a semiconductor module that constitutes the upper and lower arm circuit 10U, a semiconductor module 30V that constitutes the upper and lower arm circuit 10V, and a semiconductor module that constitutes the upper and lower arm circuit 10W. The three semiconductor modules 30 are arranged side by side in the X direction.

[0029] All semiconductor modules 30 have a common structure. Each semiconductor module 30 is equipped with a encapsulant 34 and an external connection terminal 32 protruding from the encapsulant 34. The semiconductor element 33 is formed by creating the above-described n-channel type MOSFET 13 and FWD 14 on a semiconductor substrate made of SiC. The MOSFET 13 has a vertical structure so that the main current flows in the thickness direction of the semiconductor element 33 (semiconductor substrate). The semiconductor element 33 has main electrodes on both sides in the thickness direction of its own. Specifically, each semiconductor element 33 has a drain electrode on one side and a source electrode on the back side.

[0030] The main current flows between the drain electrode and the source electrode. The semiconductor element 33 of this embodiment includes two semiconductor elements 33H that provide the high-side switching elements of the series circuit 12, and two semiconductor elements 33L that provide the low-side switching elements of the series circuit 12. The semiconductor elements 33H and 33L are arranged side by side in the Y direction.

[0031] The encapsulant 34 encloses parts of the semiconductor element 33 and the external connection terminals 32. Other parts of the external connection terminals 32 protrude outside the encapsulant 34. The encapsulant 34 has, for example, a roughly rectangular shape in plan.

[0032] The multiple external connection terminals 32 include main terminals 32P, 32N, 32O, and signal terminal 32S. One end of main terminals 32P and 32N is electrically connected to the main electrode of the semiconductor element 33, and the other end of main terminals 32P and 32N is electrically connected to the smoothing capacitor 6. Of the multiple main terminals 32, the portions that protrude from the side of the encapsulant 34 are arranged in the X direction. The signal terminal 32S also protrudes from the side.

[0033] The main terminal 32O is electrically connected to the connection point between the source electrode of semiconductor element 33H and the drain electrode of semiconductor element 33L, that is, to the connection point (midpoint) of the series circuit 12. The main terminal 32O protrudes outward from the side of the encapsulant 34 opposite to the main terminals 32P and 32N. The main terminal 32O is connected to the corresponding winding 3a of the motor 3, for example, via a busbar (not shown).

[0034] A heat conductive member is interposed between the semiconductor module 30 and the first cooler 21. The heat conductive member transfers the heat generated by the semiconductor element 33 to the first cooler 21. The heat conductive member is an electrically insulating thermal conductive grease or thermal conductive gel.

[0035] The second cooler 40 is provided without reusing the base 20. The second cooler 40 is positioned on the upper surface of the semiconductor module 30 and cools the semiconductor module 30 from the opposite side from the first cooler 21. Together, the second cooler 40 and the first cooler 21 can cool the semiconductor module 30 from both sides in the Z direction. The second cooler 40 has a flow path 41 inside it. A refrigerant 42 flows through the flow path 41. The second cooler 40 is connected to the first cooler 21, and the refrigerant 42 is the same as the refrigerant 212 described above.

[0036] The circuit board 60 has electronic components 61 such as a microcomputer and connectors 62 mounted on it. Furthermore, the circuit board 60 has electronic components that constitute the drive circuit 7 described above mounted on it. In a plan view in the Z direction, the circuit board 60 is arranged to overlap with the semiconductor module 30 and the capacitor module 50. The signal terminals 32S of the three semiconductor modules 30 are mounted on the circuit board 60. The circuit board 60 is located in the housing space of the case 22.

[0037] Connector 62 is connected to external connector 62b by harness 62a. External connector 62b is mounted on the side wall 23. External connectors (not shown) are connected to external connector 62b, thereby enabling communication between the circuit board 60 and external equipment. For example, signals such as battery information, inverter information, and vehicle information are communicated between the circuit board 60 and external equipment via external connector 62b and harness 62a, etc.

[0038] The circuit board 60 is supported by a board stay 70, and the board stay 70 is supported by a base 20. For example, the board stay 70 is fixed to the base 20 with bolts. The board stay 70 is formed from a metal material such as aluminum. The board stay 70 may be in the shape of a beam or a plate. In the example shown in Figure 2, the board stay 70 is formed in the shape of a plate and is placed between the semiconductor module 30 and the circuit board 60. In this way, the board stay 70 also functions as a shielding member that protects the circuit board 60 from noise electromagnetic waves radiated from the semiconductor module 30.

[0039] Furthermore, the board stay 70 is also located between the capacitor module 50 and the circuit board 60. This means that the board stay 70 also has the function of protecting the circuit board 60 from noise electromagnetic waves radiated from the capacitor module 50. In addition, the board stay 70 may be located between the harness 62a and the external connector 62b and the capacitor module 50 to protect the harness 62a and the external connector 62b from the aforementioned noise electromagnetic waves.

[0040] As shown in Figures 2 and 3, the capacitor module 50 includes a capacitor element 53, a Y-con element 54, a case 55, a molded resin body 56, busbars 51P and 51N, and a shielding member 57. The capacitor module 50 corresponds to a "capacitor device". The smoothing capacitor 6 described above is provided by a plurality of capacitor elements 53 connected in parallel.

[0041] The case 55 is made of resin and is a housing having an opening 55a. The case 55 has a rectangular shape when viewed in the Z direction. In the example shown in Figure 3, the opening 55a opens upward, but it may also open in the Y direction toward the semiconductor module 30.

[0042] The capacitor element 53 and the Y-con element 54 are housed inside the case 55. The molded resin body 56 is a resin that has been injected into the case 55 and solidified, sealing the capacitor element 53 and the Y-con element 54. This prevents moisture from the air from coming into contact with the capacitor element 53 and the Y-con element 54, thereby suppressing the deterioration of the capacitor element 53 and the Y-con element 54.

[0043] The capacitor element 53 is a film capacitor element and has a pair of film electrodes 53a (internal electrodes), a film dielectric 53b, and a pair of external electrodes 53c. The film electrodes 53a and the film dielectric 53b are wound together with the film dielectric 53b interposed between the pair of film electrodes 53a. The wound body of the film electrodes 53a and the film dielectric 53b has an elliptical, flattened cylindrical shape.

[0044] A pair of external electrodes 53c are positioned to sandwich the winding body from both sides. The external electrodes 53c are flat plates, and their surfaces are oriented perpendicular to the center line C. In the example shown in Figure 3, the external electrodes 53c are positioned on the upper and lower sides of the winding body in the Z direction. One surface of the external electrodes 53c is electrically connected to the film electrode 53a, and the other surface is electrically connected to the busbars 51P and 51N. As a result, the positive electrode side of the pair of film electrodes 53a is electrically connected to the busbar 51P, and the negative electrode side is electrically connected to the busbar 51N.

[0045] In the example shown in Figure 3, the capacitor elements 53 are arranged with the winding center line C in the Z direction, but the capacitor elements 53 may also be arranged with the center line C in the X or Y direction. Multiple capacitor elements 53 are arranged so that the orientation of the center line C is the same. In the example shown in Figure 2, multiple capacitor elements 53 are arranged in a line perpendicular to the vertical direction. Also, multiple capacitor elements 53 are arranged in a line in the Y direction, where the capacitor module 50 and semiconductor module 30 are aligned. The capacitor module 50 is arranged on one surface 20a of the base 20 that constitutes the first cooler 21.

[0046] Busbars 51P and 51N are plate-shaped metal components. One end of busbars 51P and 51N is connected to the external electrode 53c by soldering, resistance welding, laser welding, or the like. The other end of busbars 51P and 51N is connected to connecting busbars 52P and 52N by bolts, welding, or the like.

[0047] The connecting busbars 52P and 52N are plate-shaped metal members. The connecting busbars 52P and 52N may be held in a predetermined positional relationship by, for example, an insulating member (not shown). The pair of connecting busbars 52P and 52N are arranged so that their plate surfaces face each other for most of their length in order to reduce inductance. The connecting busbar 52P electrically connects the main terminal 32P of the semiconductor module 30 and the busbar 51P of the capacitor module 50, forming the current path for the P line 8. The connecting busbar 52N electrically connects the main terminal 32N of the semiconductor module 30 and the busbar 51N of the capacitor module 50, forming the current path for the N line 9.

[0048] The busbar 51N has an extension 51Na that extends vertically from the bottom surface of the case 55 toward the opening 55a. The busbar plate surface of the extension 51Na faces both the side surface of the case 55 and the side surface of the capacitor element 53. The extension 51Na is located inside the case 55 and is sealed by a molded resin body 56.

[0049] An alternating current flows between the pair of external electrodes 53c, but as shown by the dotted arrow in Figure 3, the direction of the current flowing between the external electrodes 53c and the direction of the current flowing through the extension portion 51Na are opposite. Therefore, the direction of the magnetic field generated by the current flowing inside the capacitor element 53 and the direction of the magnetic field generated by the current flowing through the extension portion 51Na cancel each other out. This reduces the impedance of the current flowing through the busbar 51N. Similarly, in the extension portions 52Pa and 52Na of the connecting busbars 52P and 52N, which are arranged facing each other, impedance reduction is achieved by arranging them in close proximity and facing each other.

[0050] As shown in Figure 1, a Y-con element 54 is connected between the P line 8 and ground, and another Y-con element 54 is connected between the N line 9 and ground. The Y-con element 54 is a filter component that reduces noise generated by the switching operation of the semiconductor element 33. These Y-con elements 54 are filter capacitors that remove power supply noise from the DC power supply 2, and are also called noise absorption capacitors.

[0051] As shown in Figure 4, the Y-con element 54 has a pair of film electrodes 54a (internal electrodes), a film dielectric 54b, and a pair of external electrodes 54c. The Y-con element 54 is a film capacitor element similar to the capacitor element 53. The film electrodes 54a and the film dielectric 54b are wound with the film dielectric 54b interposed between the pair of film electrodes 54a. The wound body of the film electrodes 54a and the film dielectric 54b has an elliptical, flattened cylindrical shape.

[0052] One of the pair of external electrodes 54c is connected to the P line 8 or N line 9 by being connected to external electrode 53c. The other of the pair of external electrodes 54c is connected to a member that is at ground potential. In the example shown in Figure 4, the other of the pair of external electrodes 54c is at ground potential by being connected to the shield member 57 via a connecting member 54d.

[0053] In the example shown in Figure 4, the Y-con elements 54 are arranged with the center line C in the Z direction, but the Y-con elements 54 may also be arranged with the center line C in the X or Y direction. Multiple Y-con elements 54 are arranged so that the orientation of the center line C is the same. In the examples shown in Figures 4 and 5, multiple Y-con elements 54 are arranged in a line perpendicular to the vertical direction. Also, multiple Y-con elements 54 are arranged in a line in the X direction.

[0054] As shown in Figures 4 and 5, the shield member 57 is a plate-shaped metal member. The plate surface of the shield member 57 faces the side surface of the capacitor element 53 and is positioned perpendicular to the Y direction.

[0055] As previously mentioned, case 55 is rectangular in Z-direction view. Of the rectangular walls of case 55, the wall furthest from the semiconductor module 30 is designated as the first wall 551 (see Figure 4). The wall closest to the semiconductor module 30 is designated as the second wall 552 (see Figure 3). The shielding member 57 is positioned between the first wall 551 and the capacitor element 53. Within case 55, the area between the second wall 552 and the capacitor element 53 is included in the region between the capacitor element 53 and the semiconductor element 33. The extension portion 51Na of the busbar 51N is positioned in this region, and the shielding member 57 is not positioned there.

[0056] Furthermore, the shielding member 57 is positioned between the capacitor element 53 and the Y-con element 54. The shielding member 57 covers the entire capacitor element 53 in the Y direction. Also, the shielding member 57 covers the entire Y-con element 54 in the Y direction.

[0057] The shield member 57 is positioned inside the case 55 and is sealed together with the capacitor element 53 by a molded resin body 56. The shield member 57 has an extension portion 57a ​​that extends from the molded resin body 56. The extension portion 57a ​​extends from the inside to the outside of the case 55 through the opening 55a. The tip of the extension portion 57a ​​is provided with a connecting portion 57b that is connected to a member that is at ground potential. The connecting portion 57b is connected to the substrate stay 70 by means of bolts or the like. In other words, the substrate stay 70 corresponds to the member that is at ground potential. The substrate stay 70 is supported by the case 22 (inverter case) and is electrically connected to the case 22.

[0058] As shown in Figure 6, a bracket 3BKT is provided on the motor case 3CS that houses the motor 3. The case 22 is supported by the motor case 3CS by being attached to the bracket 3BKT. The motor case 3CS is attached to and supported by the vehicle frame 1FRM. The vehicle frame 1FRM, motor case 3CS, bracket 3BKT, case 22, substrate stay 70, and shield member 57 are all made of metal and are electrically connected. Since the vehicle frame 1FRM is at ground potential, the shield member 57 is also at ground potential.

[0059] In the example shown in Figure 6, the conductive path from the shield member 57 to the vehicle frame 1FRM includes, in order, the substrate stay 70, the case 22, the bracket 3BKT, and the motor case 3CS. This conductive path may be modified as appropriate. For example, the substrate stay 70 may be at the same potential (ground potential) as the vehicle frame 1FRM by directly connecting the case 22 to the vehicle frame 1FRM. Alternatively, the shield member 57 may be directly connected to the case 22 without going through the substrate stay 70. Furthermore, when the case 22 is directly connected to the motor case 3CS, the bracket 3BKT may be removed from the conductive path described above.

[0060] Furthermore, the components constituting the conductive path, such as the motor case 3CS and case 22, may be made primarily of resin. In this case, the resin material must contain a metal frame or other metal material, which provides the conductive path.

[0061] <Summary of the First Embodiment> Here, while the semiconductor module 30 naturally becomes a source of noise during switching operation, the capacitor module 50 and the capacitor element 53 also become sources of noise. The dotted arrows in Figure 4 indicate the alternating current flowing between the pair of external electrodes 53c. This alternating current generates electromagnetic noise EN. In particular, in recent years, with the use of SiC and GaN in the semiconductor element 33, the switching speed has become faster, and as a result, the electromagnetic noise EN generated by the capacitor element 53 has become large enough that it cannot be ignored.

[0062] To counteract electromagnetic noise EN radiated from such a capacitor module 50, the capacitor module 50 (capacitor device) and power converter 4 according to this embodiment are equipped with a shielding member 57. The shielding member 57 is positioned opposite the capacitor element 53 and is connected to a member (substrate stay 70) that is at ground potential. Therefore, electromagnetic noise EN radiated from the capacitor element 53 is absorbed by the shielding member 57 and its radiation to the outside of the capacitor module 50 is suppressed.

[0063] As a result, for example, it is possible to suppress the reception of electromagnetic noise EN by the harness 62a and to suppress the outflow of electromagnetic noise EN from the external connector 62b to the outside. In addition, it is possible to suppress malfunctions of the electronic component 61 due to the influence of electromagnetic noise EN.

[0064] Furthermore, in this embodiment, the capacitor module 50 includes a case 55 that houses the capacitor element 53, and a molded resin body 56 that fills the inside of the case 55 and seals the capacitor element 53. The capacitor module 50, which is modularized by including the case 55, the capacitor element 53, and the molded resin body 56, also includes a shielding member 57. Therefore, the countermeasures against electromagnetic noise EN are completed within the capacitor module 50. Thus, it is unnecessary to consider the arrangement layout of the shielding member 57 within the case 22 of the power converter 4. In addition, it is unnecessary to assemble the shielding member 57 into the case 22 separately from the capacitor module 50, improving assembly workability.

[0065] Furthermore, in this embodiment, at least a portion of the shielding member 57 is located inside the case 55. Therefore, compared to the case where the shielding member 57 is attached to the outside of the case 55, the shielding member 57 can be positioned closer to the capacitor element 53, which is the noise source. Thus, the effect of suppressing electromagnetic noise EN by the shielding member 57 can be improved.

[0066] Here, if the Y-con element 54 is placed inside the case 55 and installed in the capacitor module 50, there is a concern that electromagnetic noise EN radiated from the capacitor element 53 will couple to the Y-con element 54. If such a coupling occurs, not only will the Y-con element 54 be unable to perform its filtering function, but the Y-con element 54 will also become a path for the outflow of electromagnetic noise EN.

[0067] In view of this point, in this embodiment, in a capacitor module 50 equipped with a Y-con element 54 (filter component) sealed by a molded resin body 56, the shielding member 57 is arranged between the capacitor element 53 and the Y-con element 54. Therefore, the Y-con element 54 can be protected from electromagnetic noise EN, and the above-mentioned problems caused by electromagnetic noise EN coupling to the Y-con element 54 can be suppressed.

[0068] Here, the electromagnetic noise EN radiated from the capacitor element 53 is strongly emitted in a direction perpendicular to the direction in which the pair of external electrodes 53c face each other (Z direction). In consideration of this point, in this embodiment, the capacitor element 53 has a film electrode 53a (internal electrode), a film dielectric 53b, and an external electrode 53c. The external electrode 53c is positioned opposite the cylindrical bottom surface of the film electrode 53a. In this case, electromagnetic noise EN is strongly emitted from the outer surface of the cylinder. Since the shielding member 57 is positioned opposite this outer surface of the cylinder, it can effectively absorb the electromagnetic noise EN.

[0069] Furthermore, in this embodiment, the shielding member 57 is prohibited from being placed in the region between the capacitor element 53 and the semiconductor element 33. Specifically, it is prohibited from being placed in the region between the second wall surface 552 and the capacitor element 53. Therefore, the distance between the capacitor element 53 and the semiconductor element 33 can be shortened, and consequently, the current path between the capacitor element 53 and the semiconductor element 33 can be shortened, making it easier to reduce inductance.

[0070] (Second Embodiment) In the first embodiment described above, the multiple capacitor elements 53 are arranged in a single row in the direction (Y direction) in which the semiconductor module 30 and the capacitor module 50 are aligned. Furthermore, a shielding member 57 is placed between the first wall surface 551 and the capacitor elements 53. In contrast, in this embodiment, as shown in Figure 7, the multiple capacitor elements 53 are arranged in a single row in the X direction, which is perpendicular to the direction in which the semiconductor module 30 and the capacitor module 50 are aligned. Furthermore, a shielding member 57 is placed between the first wall surface 551 and the multiple capacitor elements 53.

[0071] The shielding member 57 covers all capacitor elements 53 from the Y direction. In this embodiment, as in the first embodiment, electromagnetic noise EN radiated from the capacitor elements 53 is absorbed by the shielding member 57 and its radiation to the outside of the capacitor module 50 is suppressed.

[0072] (Third embodiment) In the shield member 57 of the second embodiment described above, the shield member 57 is positioned between a plurality of capacitor elements 53 and the first wall surface 551. In contrast, in this embodiment, as shown in Figure 8, the shield member 57 has a second shield wall 572 in addition to the first shield wall 571. The shield member 57 is formed by bending a single metal plate to integrally create the first shield wall 571 and the second shield wall 572.

[0073] The first shield wall 571 is positioned between the plurality of capacitor elements 53 and the first wall surface 551, similar to the shield member 57 in the second embodiment. The second shield wall 572 is positioned between the third wall surface 553 of the case 55 and the capacitor elements 53. The third wall surface 553 is the wall surface of the rectangular case 55 that connects the first wall surface 551 and the second wall surface 552, and is a wall surface that extends perpendicular to the X direction.

[0074] According to this embodiment, the shielding member 57 has a second shielding wall 572 in addition to the first shielding wall 571. Therefore, the electromagnetic noise EN radiation suppression effect of the shielding member 57 can be improved not only in the Y direction but also in the X direction.

[0075] (Fourth Embodiment) In this embodiment, as shown in Figure 9, the shield member 57 has a first shield wall 571 and a second shield wall 572, as well as a third shield wall 573. The shield member 57 is formed integrally by bending a single metal plate to create the first shield wall 571, the second shield wall 572, and the third shield wall 573.

[0076] The third shield wall 573 is positioned between the multiple capacitor elements 53 and the second wall surface 552. The third shield wall 573 covers all the capacitor elements 53 from the side of the semiconductor module 30 in the Y direction. In contrast, the first shield wall 571 covers all the capacitor elements 53 from the opposite side of the semiconductor module 30 in the Y direction. In short, the first shield wall 571, the second shield wall 572, and the third shield wall 573 are positioned to surround the entire cylindrical outer surface of the multiple capacitor elements 53.

[0077] According to this embodiment, the shielding member 57 has a third shielding wall 573 in addition to the first shielding wall 571 and the second shielding wall 572. Therefore, the electromagnetic noise EN radiation suppression effect by the shielding member 57 can be improved over the entire outer surface of the cylinder of the capacitor element 53.

[0078] (Fifth embodiment) In the embodiments described above, the shield member 57 is located inside the case 55. In contrast, in this embodiment, as shown in Figure 10, the shield member 57 is located outside the case 55. However, the shield member 57 is assembled to the case 55 and is included in the capacitor module 50. The shield member 57 may also be insert-molded into the case 55 and embedded inside the case 55.

[0079] (Sixth Embodiment) In the fifth embodiment described above, the shield member 57 is assembled to the case 55 and is included in the capacitor module 50. In contrast, in this embodiment, as shown in Figure 11, the shield member 57 is assembled to a component separate from the case 55 and is not included in the capacitor module 50. In other words, the process of assembling the capacitor module 50 to the case 22 and the process of assembling the shield member 57 to the case 22 are separate.

[0080] For example, the shielding member 57 may be assembled to the circuit board stay 70 when it is positioned outside the capacitor case (case 55), or it may be assembled to the inverter case (case 22). This improves the flexibility of placement when arranging the shielding member 57 inside the case 22. For example, the shielding member 57 can be placed near components such as the harness 62a that need to be protected from electromagnetic noise EN, thereby improving electromagnetic noise countermeasures for specific components.

[0081] (Other embodiments) Although several embodiments of this disclosure have been described above, it is not limited to the combinations of configurations explicitly stated in the description of each embodiment. In addition, configurations from multiple embodiments can be partially combined even if not explicitly stated, as long as there are no particular problems with the combination. Furthermore, combinations of configurations described in the multiple embodiments and variations that are not explicitly stated are also disclosed in the following description.

[0082] In the embodiments described above, a metal plate is used for the shielding member 57. However, the shielding member 57 may also be a braided cloth or a conductive film woven with a conductive material. Furthermore, the material of the shielding member 57 can be any conductive material and is not limited to metals such as aluminum.

[0083] In each of the above embodiments, a Y-con element 54, which suppresses common-mode noise, is applied to the filter component protected by the shielding member 57. In contrast, an X-capacitor, which suppresses differential-mode noise by being connected between the P-line 8 and the N-line 9, may be applied as the filter component to be protected. Furthermore, the filter component may not be housed in the case 55 and may be located outside the case 55. Also, the filter component may be omitted.

[0084] In each of the above embodiments, a smoothing capacitor 6 is applied to the capacitor element 53 used in the capacitor module 50. In contrast, an input capacitor, as described below, may be applied to the capacitor element 53. Alternatively, both a smoothing capacitor 6 and an input capacitor may be provided in the capacitor module 50. An input capacitor is a capacitor that constitutes a boost circuit. The boost circuit comprises a reactor and an input capacitor and boosts the voltage of the DC power supply 2. The input capacitor functions to store and charge / discharge the boosted energy.

[0085] In the examples shown in Figures 2 and 5, the shield member 57 is at ground potential because the connection portion 57b of the shield member 57 is connected to the substrate stay 70. Alternatively, the shield member 57 may be at ground potential if the connection portion 57b is directly connected to the case 22 (base 20). Here, the case 55 is attached to the base 20. The case 55 has a bracket (not shown), and the bracket is fixed to the base 20 by fastening members such as bolts. The shield member 57 may be at ground potential by fastening the connection portion 57b together with this bracket.

[0086] In each of the above embodiments, the shield member 57 is positioned opposite the cylindrical outer surface of the film electrode 53a (internal electrode), and is not positioned opposite the ends of the cylinder, i.e., opposite the external electrode 53c. In contrast, the shield member 57 may be positioned opposite the external electrode 53c.

[0087] (Disclosure of technical ideas) This specification discloses several technical concepts, as listed in the following paragraphs. Some paragraphs are written in a multiple dependent form, where subsequent paragraphs optionally refer to preceding paragraphs. Furthermore, some paragraphs are written in a multiple dependent form, referring to other multiple dependent forms. These paragraphs written in multiple dependent forms define several technical concepts.

[0088] (Technical thought 1) A capacitor element (53) is connected to a semiconductor element (33) that performs switching operation to convert power, A shielding member (57) is positioned opposite the capacitor element and absorbs electromagnetic noise generated by the alternating current flowing between the electrodes of the capacitor element, Equipped with, The shielding member is connected to a member that is at ground potential, and is part of a capacitor device.

[0089] (Technical thought 2) The device comprises a case (55) that houses the capacitor element inside, and a molded resin body (56) that is filled inside the case to seal the capacitor element. The capacitor device according to technical concept 1, wherein the capacitor module (50), which is modularized including the case, the capacitor element, and the molded resin body, also includes the shielding member.

[0090] (Technical Thought 3) The capacitor device according to technical concept 2, wherein at least a portion of the shielding member is located inside the case.

[0091] (Technical Thought 4) The molded resin body is sealed and includes a filter component (54) that reduces noise generated by the switching operation, The shielding member is disposed between the capacitor element and the filter component in the capacitor device according to technical concept 2 or 3.

[0092] (Technical Thought 5) The aforementioned capacitor element is A pair of internal electrodes (53a) wound to form a cylindrical shape, A dielectric (53b) is disposed between the pair of internal electrodes, It has a pair of external electrodes (53c) that are connected to the internal electrodes and also to busbars (51P, 51N), The external electrode is positioned opposite the cylindrical bottom surface of the internal electrode, The capacitor device according to any one of technical concepts 1 to 4, wherein the shielding member is arranged opposite to the cylindrical outer surface of the internal electrode.

[0093] (Technical Thought 6) The capacitor device according to any one of technical ideas 1 to 5, wherein the shielding member is prohibited from being placed in the region between the capacitor element and the semiconductor element, and is located outside the region.

[0094] (Technical Thought 7) A semiconductor module (30) that performs switching operation to convert power, A capacitor element (53) connected to the semiconductor module, A shielding member (57) is positioned opposite the capacitor element and absorbs electromagnetic noise generated by the alternating current flowing between the electrodes of the capacitor element, Equipped with, The shielding member is connected to a member that is at ground potential, and is part of a power conversion device. [Explanation of symbols]

[0095] 30...Semiconductor module, 33...Semiconductor element, 50...Capacitor module, 51P, 51N...Busbar, 53...Capacitor element, 53a...Film electrode (internal electrode), 53b...Dielectric, 53c...External electrode, 54...Y-converter element (filter component), 55...Case, 56...Molded resin body, 57...Shielding member.

Claims

1. A capacitor element (53) is connected to a semiconductor element (33) that performs switching operation to convert power, A shielding member (57) is positioned opposite the capacitor element and absorbs electromagnetic noise generated by the alternating current flowing between the electrodes of the capacitor element, Equipped with, The shielding member is connected to a member that is at ground potential, and is part of a capacitor device.

2. The device comprises a case (55) that houses the capacitor element inside, and a molded resin body (56) that is filled inside the case to seal the capacitor element. The capacitor device according to claim 1, wherein the capacitor module (50), which is modularized including the case, the capacitor element, and the molded resin body, also includes the shielding member.

3. The capacitor device according to claim 2, wherein at least a portion of the shielding member is located inside the case.

4. The molded resin body is sealed and includes a filter component (54) that reduces noise generated by the switching operation, The capacitor device according to claim 2 or 3, wherein the shielding member is disposed between the capacitor element and the filter component.

5. The aforementioned capacitor element is A pair of internal electrodes (53a) wound to form a cylindrical shape, A dielectric (53b) is disposed between the pair of internal electrodes, It has a pair of external electrodes (53c) that are connected to the internal electrodes and also to busbars (51P, 51N), The external electrode is positioned opposite the cylindrical bottom surface of the internal electrode, The capacitor device according to any one of claims 1 to 3, wherein the shielding member is arranged opposite to the cylindrical outer surface of the internal electrode.

6. The capacitor device according to any one of claims 1 to 3, wherein the shielding member is prohibited from being placed in the region between the capacitor element and the semiconductor element, and is placed outside the region.

7. A semiconductor module (30) that performs switching operation to convert power, A capacitor element (53) connected to the semiconductor module, A shielding member (57) is positioned opposite the capacitor element and absorbs electromagnetic noise generated by the alternating current flowing between the electrodes of the capacitor element, Equipped with, The shielding member is connected to a member that is at ground potential, and is part of a power conversion device.

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