Electric device and air conditioner

Abstract

Provided is a technology by which it is possible to suitably suppress outflow of a common mode current to a power supply side. A power conversion device 200 according to one embodiment of the present disclosure comprises: a noise filter 220 that includes a common mode choke coil 221, and in which, between one end side and another end side, the other end side is electrically connected to a power device 233PD; power supply lines L_R3, L_S3 and L_T3, and power supply lines L_R4, L_S4 and L_T4 that are connected to the one end side and the other end side of the common mode choke coil; a conductor unit 260 that has an inner surface 110Hs facing the power supply lines L_R4, L_S4 and L_T4; and a dielectric 250 that is disposed between the conductor unit 260 and the power supply lines L_R4, L_S4 and L_T4. The dielectric 250 is arranged such that a surface 250s1 faces the inner surface 110Hs of the conductor unit 260, and a surface 250s2 on the side opposite the surface 250s1 faces surfaces WPs1, WPs2, and WPs3 of the power supply lines L_R4, L_S4, and L_T4.

Description

Electrical equipment, air conditioners

[0001] The present disclosure relates to electrical devices and the like.

[0002] Common-mode voltages caused by the switching operations of switching devices can cause common-mode noise currents (hereinafter referred to as "common-mode currents") to flow to the power supply side through the ground of the housing, etc., resulting in an increase in radiated noise.

[0003] In response to this, for example, a technique is known in which a capacitor (ground capacitor or bypass capacitor) is placed in a bypass path connecting the ground side with a power line or a signal line, and the common mode current that has flowed to the ground side is returned to the noise source (see Patent Document 1).

[0004] Patent No. 5433987

[0005] However, for example, if the switching frequency of the switching device is high, the parasitic inductance of the capacitor's lead wires will have a large effect in the high-frequency band where radiated noise becomes a problem, increasing the impedance of the bypass path. This makes it difficult for high-frequency common-mode current to return to the bypass path, and the outflow of common-mode current to the power supply cannot be sufficiently suppressed, potentially increasing radiated noise.

[0006] An object of the present disclosure is to provide a technique capable of appropriately suppressing the outflow of common mode current to the power supply side.

[0007] In a first aspect of the present disclosure, there is provided an electrical device comprising: a noise filter including a common mode choke coil, the other of one end being electrically connected to a switching device; a first wiring portion connected to one end of the common mode choke coil; a second wiring portion connected to the other end of the common mode choke coil; a conductor member having a surface facing the first wiring portion or the second wiring portion; and a dielectric disposed between the conductor member and one of the first wiring portion and the second wiring portion, wherein the dielectric is disposed such that a first surface faces a surface of the conductor member and a second surface opposite to the first surface faces a surface of one of the wiring portions.

[0008] According to this aspect, the stray capacitance between either the first wiring portion or the second wiring portion and the conductor member can be increased. Therefore, the electric device can return the common-mode current flowing into the conductor member due to the common-mode voltage caused by the switching operation of the switching device to the switching device, which is a noise source, via the stray capacitance. Furthermore, because the stray capacitance does not include inductance components such as lead wires, there is no increase in impedance even at high frequencies, and the electric device can sufficiently return the high-frequency common-mode current to the switching device via the stray capacitance. Therefore, the electric device can appropriately suppress the flow of the common-mode current to the power supply side.

[0009] Furthermore, in a second aspect of the present disclosure, based on the first aspect described above, the dielectric may be arranged so that both the first surface and a surface of the conductor member, and the second surface and a surface of either one of the wiring portions, are in contact.

[0010] Furthermore, in a third aspect of the present disclosure, based on the first aspect described above, the dielectric may be arranged so that either the first surface and a surface of the conductor member, or the second surface and a surface of either one of the wiring portions, are in contact with each other and are in close proximity to each other.

[0011] Furthermore, in a fourth aspect of the present disclosure, based on the first aspect described above, the dielectric may be arranged so that both the first surface and the surface of the conductor member, and the second surface and the surface of either one of the wiring portions, are in close proximity to each other.

[0012] Furthermore, in a fifth aspect of the present disclosure, based on any one of the first to fourth aspects described above, the dielectric may be disposed between the conductor member and the second wiring portion.

[0013] In addition, in a sixth aspect of the present disclosure, based on any one of the first to fifth aspects described above, the dielectric may have a relative dielectric constant of 5 or more in a frequency band of 300 MHz or less.

[0014] In addition, in a seventh aspect of the present disclosure, based on any one of the first to sixth aspects described above, the material of the dielectric may include silicone resin or urethane.

[0015] In addition, in an eighth aspect of the present disclosure, based on any one of the first to seventh aspects described above, the dielectric may have impact absorption properties.

[0016] Furthermore, in a ninth aspect of the present disclosure, based on any one of the first to eighth aspects described above, the ninth aspect may include the switching device, the second wiring portion may be connected between the other end of the common mode choke coil and the switching device, and the conductor member may be located in the vicinity of the switching device and have a surface facing either one of the wiring portions.

[0017] Furthermore, in a tenth aspect of the present disclosure, based on the above-described ninth aspect, the conductor member may include a heat dissipation member thermally coupled to the switching device.

[0018] Furthermore, an eleventh aspect of the present disclosure may be based on the ninth or tenth aspect, and further comprises an inverter or a converter including the switching device.

[0019] Furthermore, a twelfth aspect of the present disclosure may be based on any one of the ninth to eleventh aspects described above, and may further include a first substrate on which the noise filter is mounted, and a second substrate different from the first substrate, on which the switching device is mounted.

[0020] In addition, in a thirteenth aspect of the present disclosure, based on any one of the ninth to twelfth aspects described above, the switching device may include a switching element formed of a wide bandgap semiconductor.

[0021] In addition, in a fourteenth aspect of the present disclosure, based on any one of the ninth to thirteenth aspects described above, a switching frequency of the switching device may be 20 kHz or more.

[0022] Furthermore, in a fifteenth aspect of the present disclosure, based on any one of the ninth to fourteenth aspects described above, a switching speed of the switching device may be 10 nanoseconds or less.

[0023] A sixteenth aspect of the present disclosure provides an air conditioner including the electrical device according to any one of the first to fifteenth aspects.

[0024] According to the above-described embodiment, it is possible to appropriately suppress the outflow of common mode current to the power supply side.

[0025] FIG. 1 is a diagram showing an example of a refrigerant circuit of an air conditioner. FIG. 2 is a diagram showing the configuration of an example of a power conversion device. FIG. 3 is a diagram showing an example of the structure of a power conversion device. FIG. 4 is a diagram showing an equivalent circuit in which a power conversion device according to a comparative example is expressed in common mode. FIG. 5 is a diagram showing an example of the relationship between the frequency of stray capacitance and parasitic inductance and the impedance. FIG. 6 is a diagram showing an equivalent circuit in which an example of a power conversion device is expressed in common mode.

[0026] Hereinafter, an embodiment will be described with reference to the drawings.

[0027] [Outline of Air Conditioner] An outline of an air conditioner 100 according to this embodiment will be described with reference to FIG.

[0028] FIG. 1 is a diagram showing an example of a refrigerant circuit of an air conditioner 100.

[0029] 1, the air conditioner 100 includes an outdoor unit 110, an indoor unit 120, and refrigerant paths 130 and 140. The air conditioner 100 operates a refrigeration cycle made up of the outdoor unit 110, the indoor unit 120, and the refrigerant paths 130 and 140, etc., to adjust the temperature, humidity, etc., of the room in which the indoor unit 120 is installed.

[0030] The outdoor unit 110 is placed outside a building whose temperature and other conditions are to be regulated. The outdoor unit 110 is connected to one end of each of the refrigerant paths 130 and 140, and draws in refrigerant from one of the refrigerant paths 130 and 140 and discharges the refrigerant to the other.

[0031] The indoor unit 120 is placed in a room of a building whose temperature and other conditions are to be adjusted. The indoor unit 120 is connected to the other end of each of the refrigerant paths 130 and 140, and draws in refrigerant from one of the refrigerant paths 130 and 140 and discharges the refrigerant to the other.

[0032] The refrigerant paths 130 and 140 are, for example, configured by pipes, and connect the outdoor unit 110 and the indoor unit 120 so that the refrigerant can circulate between the outdoor unit 110 and the indoor unit 120 .

[0033] The outdoor unit 110 includes refrigerant paths L1 to L6, oil paths L7 and L8, a four-way switching valve 111, an accumulator 112, a compressor 113, an oil separator 114, an outdoor heat exchanger 115, an outdoor expansion valve 116, and a fan 117.

[0034] The refrigerant paths L1 to L6 are configured as, for example, pipes.

[0035] The refrigerant path L1 connects one end of the refrigerant path 130 outside the outdoor unit 110 to the four-way switching valve 111 .

[0036] The refrigerant path L2 connects the four-way switching valve 111 and the inlet of the compressor 113. The refrigerant path L2 includes refrigerant paths L21 and L22.

[0037] The refrigerant path L21 connects the four-way switching valve 111 and the accumulator 112. The refrigerant path L22 connects the accumulator 112 and the inlet of the compressor 113.

[0038] The refrigerant path L3 connects the four-way switching valve 111 and the outlet of the compressor 113. The refrigerant path L3 includes refrigerant paths L31 and L32.

[0039] The refrigerant path L31 connects the outlet of the compressor 113 and the oil separator 114. The refrigerant path L32 connects the four-way switching valve 111 and the oil separator 114.

[0040] The refrigerant path L4 connects the four-way switching valve 111 and the outdoor heat exchanger 115.

[0041] The refrigerant path L5 connects the outdoor heat exchanger 115 and the outdoor expansion valve 116 .

[0042] The refrigerant path L6 connects one end of the refrigerant path 140 outside the outdoor unit 110 to the outdoor expansion valve 116 .

[0043] The oil path L7 is configured as, for example, a pipe line, and is used to allow the oil separated by the oil separator 114 to flow into the refrigerant path L22 and return the oil to the compressor 113 through the refrigerant path L22.

[0044] The oil passing through the oil path L7 may contain, for example, a liquid refrigerant (hereinafter referred to as "liquid refrigerant"). In other words, not only oil but also liquid refrigerant flows through the oil path L7.

[0045] The oil path L8 is configured as, for example, a pipe line, and is used to allow oil containing liquid refrigerant separated by the accumulator 112 to flow into the refrigerant path L22 and return it to the compressor 113 through the refrigerant path L22.

[0046] The four-way switching valve 111 reverses the flow of circulating refrigerant when the air conditioner 100 is in cooling operation and when it is in heating operation.

[0047] During cooling operation of the air conditioner 100, the four-way switching valve 111 connects the paths indicated by the solid lines in Fig. 1. Specifically, during cooling operation of the air conditioner 100, the four-way switching valve 111 connects refrigerant path L1 to refrigerant path L2, and refrigerant path L3 to refrigerant path L4.

[0048] On the other hand, when the air conditioner 100 is in heating operation, the four-way switching valve 111 connects the paths indicated by the dotted lines in Fig. 1. Specifically, when the air conditioner 100 is in heating operation, the four-way switching valve 111 connects the refrigerant path L4 to the refrigerant path L2, and the refrigerant path L1 to the refrigerant path L3.

[0049] The accumulator 112 separates the liquid refrigerant contained in the refrigerant drawn from the refrigerant path L21 and discharges the refrigerant from which some or all of the liquid refrigerant has been removed to the refrigerant path L22. The liquid refrigerant separated in the accumulator 112 contains oil. The accumulator 112 is provided with an oil discharge port connected to the oil path L8, and the separated oil containing the refrigerant flows out into the oil path L8 through the oil discharge port and is returned to the compressor 113 through the oil path L8 and the refrigerant path L22.

[0050] The compressor 113 draws in the refrigerant from the refrigerant path L22, compresses it to a high pressure, and discharges it to the refrigerant path L31.

[0051] During cooling operation of the air conditioner 100, high-temperature, high-pressure refrigerant compressed by the compressor 113 flows into the outdoor heat exchanger 115 via refrigerant paths L3 and L4.

[0052] On the other hand, during heating operation of the air conditioner 100, the high-temperature, high-pressure refrigerant compressed by the compressor 113 flows through refrigerant path L3 and refrigerant path L1 into refrigerant path 130 outside the outdoor unit 110. The high-temperature, high-pressure refrigerant then flows into the indoor unit 120 through refrigerant path 130.

[0053] The oil separator 114 separates oil from the refrigerant flowing in from the refrigerant path L31, and discharges the refrigerant from which some or all of the oil has been separated and removed into the refrigerant path L32. The oil separator 114 is also provided with an oil outlet connected to the oil path L7, and the oil separated from the refrigerant flows into the oil path L7 through the oil outlet and is returned to the compressor 113 through the oil path L7 and the refrigerant path L22.

[0054] The outdoor heat exchanger 115 exchanges heat between the outside air and the refrigerant passing through it. Specifically, the outdoor heat exchanger 115 is provided with a fan 117, and the outdoor heat exchanger 115 exchanges heat between the outside air blown by the fan 117 and the refrigerant flowing through it.

[0055] When the air conditioner 100 is operating in cooling mode, the outdoor heat exchanger 115 causes the high-temperature, high-pressure refrigerant compressed by the compressor 113, which flows in from the refrigerant path L4, to radiate heat to the outside air, and then causes the condensed and liquefied refrigerant (liquid refrigerant) to flow into the refrigerant path L5.

[0056] Furthermore, during heating operation of the air conditioner 100, the outdoor heat exchanger 115 causes the low-temperature, low-pressure liquid refrigerant flowing in from the refrigerant path L5 to absorb heat from the outside air, and causes the evaporated refrigerant to flow into the refrigerant path L4.

[0057] The outdoor expansion valve 116 is closed to a predetermined opening degree during heating operation of the air conditioner 100, and reduces the pressure of the refrigerant (liquid refrigerant) flowing in from refrigerant path L6 to a predetermined pressure. On the other hand, during cooling operation of the air conditioner 100, the outdoor expansion valve 116 is fully open, and allows the refrigerant (liquid refrigerant) to pass from refrigerant path L5 to refrigerant path L6. The outdoor expansion valve 116 is, for example, a solenoid valve.

[0058] The indoor unit 120 includes an indoor expansion valve 121 , an indoor heat exchanger 122 , and a fan 123 .

[0059] During cooling operation of the air conditioner 100, the indoor expansion valve 121 is closed to a predetermined opening degree and reduces the pressure of the supercooled liquid refrigerant flowing in from the refrigerant path 140 to a predetermined pressure. On the other hand, during heating operation of the air conditioner 100, the indoor expansion valve 121 is fully open and allows the refrigerant (liquid refrigerant) flowing out from the indoor heat exchanger 122 to pass toward the refrigerant path 140. The indoor expansion valve 121 is, for example, a solenoid valve.

[0060] The indoor heat exchanger 122 exchanges heat between the indoor air and the refrigerant passing through it. Specifically, the indoor air passes around the indoor heat exchanger 122 by the action of the fan 123 mounted in the indoor unit 120, promoting heat exchange with the refrigerant inside the indoor heat exchanger 122. Then, by the action of the fan 123, the indoor air that has exchanged heat with the refrigerant inside the indoor heat exchanger 122 is sent out to the outside of the indoor unit 120, thereby realizing cooling or heating of the room.

[0061] When the air conditioner 100 is in cooling operation, the indoor heat exchanger 122 causes the low-temperature, low-pressure liquid refrigerant decompressed by the indoor expansion valve 121 to absorb heat from the indoor air, thereby lowering the temperature of the indoor air.

[0062] On the other hand, during heating operation of the air conditioner 100, the indoor heat exchanger 122 causes the high-temperature, high-pressure refrigerant flowing in from the outdoor unit 110 through the refrigerant path 130 to radiate heat to the indoor air, thereby raising the temperature of the indoor air.

[0063] [Configuration of Power Converter] Next, the configuration of the power converter 200 mounted on the air conditioner 100 according to this embodiment will be described with reference to Figs. 2 and 3 .

[0064] Fig. 2 is a diagram showing an example of the configuration of the power conversion device 200. Fig. 3 is a diagram showing an example of the structure of the power conversion device 200.

[0065] In FIG. 3, only the housing 110H is illustrated as a cross-sectional view for convenience.

[0066] As shown in FIG. 2, the outdoor unit 110 has a housing 110H that houses its constituent elements, and includes a power conversion device 200 housed in the housing 110H.

[0067] The power conversion device 200 drives the electric motor 113M of the compressor 113 using three-phase AC power from a commercial power source PS supplied from outside the outdoor unit 110.

[0068] The power conversion device 200 includes a terminal T_FG, a power supply line L_R, a power supply line L_S, a power supply line L_T, a power supply terminal block 210 , a noise filter 220 , an inverter 230 , a heat dissipation portion 240 , and a dielectric 250 .

[0069] The terminal T_FG is provided on the housing 110H and is grounded outside the housing 110H, so that the housing 110H is regarded as a reference potential portion equivalent to ground.

[0070] The power supply lines L_R, L_S, and L_T supply three-phase AC power from the commercial power supply PS to the inverter 230 .

[0071] The power supply line L_R supplies R-phase AC power from the commercial power supply PS to the inverter 230. The power supply line L_R includes power supply lines L_R1 to L_R5.

[0072] The power supply line L_S supplies S-phase AC power from the commercial power supply PS to the inverter 230. The power supply line L_S includes power supply lines L_S1 to L_S5.

[0073] The power supply line L_T supplies T-phase AC of the commercial power supply PS to the inverter 230. The power supply line L_T includes power supply lines L_T1 to L_T5.

[0074] The power lines L_R1, L_S1, and L_T1 each connect the commercial power supply PS and the power terminal block 210. The power lines L_R2, L_S2, and L_T2 each connect the power terminal block 210 and one end of the power lines L_R3, L_S3, and L_T3 of the noise filter 220. The power lines L_R3, L_S3, and L_T3 and the power lines L_R4, L_S4, and L_T4 correspond to power lines inside the noise filter 220. For example, as shown in FIG. 3 , the power lines L_R3, L_S3, and L_T3 and the power lines L_R4, L_S4, and L_T4 are implemented as wiring patterns on the board 220PB. The power lines L_R5, L_S5, and L_T5 each connect the other ends of the power lines L_R4, L_S4, and L_T4 of the noise filter 220 and the inverter 230.

[0075] The power terminal block 210 relays and branches the three-phase AC supplied by the power lines L_R1, L_S1, and L_T1 to various devices.

[0076] One end of the power line L_R1 and one end of the power line L_R2 are connected to the power terminal block 210, electrically connecting the power line L_R1 and the power line L_R2. Similarly, one end of the power line L_S1 and one end of the power line L_S2 are connected to the power terminal block 210, electrically connecting the power line L_S1 and the power line L_S2. Similarly, one end of the power line L_T1 and one end of the power line L_T2 are connected to the power terminal block 210, electrically connecting the power line L_T1 and the power line L_T2.

[0077] The noise filter 220 suppresses noise in the current of the power conversion device 200. For example, as shown in Figures 2 and 3, the noise filter 220 includes a common mode choke coil 221 and a Y capacitor 222, and is mounted on a substrate 220PB.

[0078] The common mode choke coil 221 acts as an inductor to suppress the common mode noise currents flowing through the power supply lines L_R3, L_S3, L_T3 and the power supply lines L_R4, L_S4, L_T4.

[0079] The Y capacitor 222 has the function of returning the common mode current that has flowed out to the ground to the noise source (inverter 230). The Y capacitor 222 includes Y capacitors 222R, 222S, and 222T.

[0080] The Y capacitor 222R is provided in a bypass path connecting the power line L_R4 and the housing 110H corresponding to ground. The Y capacitor 222S is provided in a bypass path connecting the power line L_S4 and the housing 110H corresponding to ground. The Y capacitor 222T is provided in a bypass path connecting the power line L_T4 and the housing 110H corresponding to ground. For example, as shown in FIG. 3 , the Y capacitor 222 and the housing 110H are connected by a lead wire 225.

[0081] The inverter 230 generates three-phase AC of a predetermined voltage and frequency using three-phase AC supplied through the power supply lines L_R, L_S, and L_T, and outputs the three-phase AC to the electric motor 113M. This enables the power conversion device 200 to drive the compressor 113. For example, as shown in FIG. 3 , the inverter 230 is mounted on a board 230PB separate from the board 220PB on which the noise filter 220 is mounted. The inverter 230 includes a rectifier circuit 231, a smoothing circuit 232, and an inverter circuit 233.

[0082] The rectifier circuit 231 converts the three-phase AC of the power supply lines L_R5, L_S5, and L_T5 into DC and outputs it to the power supply lines L_P1 and L_N1. For example, as shown in Figure 2, the rectifier circuit 231 includes a power device 231PD. The power device 231PD is a semiconductor rectifier diode.

[0083] The smoothing circuit 232 smoothes the direct current of the power supply lines L_P1 and L_N1. For example, the smoothing circuit 232 includes a smoothing capacitor 232C and a reactor 232L.

[0084] The smoothing capacitor 232C is provided on a path connecting the power supply lines L_P1 and L_N1. The smoothing capacitor 232C smoothes the direct current output from the rectifier circuit 231 and the direct current output (regenerated) from the inverter circuit 233 by repeatedly charging and discharging as appropriate.

[0085] The reactor 232L is provided on the power supply line L_P1. For example, the reactor 232L is provided on the power supply line L_P1 between the rectifier circuit 231 and the smoothing capacitor 232C. The reactor 232L smoothes the direct current output from the rectifier circuit 231 and the direct current output (regenerated) from the inverter circuit 233 while generating a voltage that appropriately prevents changes in current.

[0086] The inverter circuit 233 is connected to the other ends of the power supply lines L_P1 and L_N1. The inverter circuit 233 includes a power device 233PD. The power device 233PD is, for example, a semiconductor switch. The semiconductor switch is, for example, an insulated gate bipolar transistor (IGBT), a metal-oxide-semiconductor field-effect transistor (MOSFET), or a high electron mobility transistor (HEMT). The semiconductor switch is, for example, primarily made of silicon (Si). The semiconductor switch may also be primarily made of a wide bandgap semiconductor material. The power device 233PD may also include, in addition to the semiconductor switch, a semiconductor freewheel diode connected in parallel with the semiconductor switch.

[0087] The inverter circuit 233 converts the DC output from the smoothing circuit 232 into three-phase AC (i.e., U-phase, V-phase, and W-phase AC) having a predetermined frequency and voltage through the switching operation of the power device 233PD, and outputs the converted AC to the electric motor 113M. The power device 233PD may have a relatively high switching speed. For example, the switching speed (i.e., the time required for switching) of the power device 233PD is 10 nanoseconds or less. The switching frequency of the power device 233PD is set to, for example, 20 kHz (kilohertz) or higher. This allows the frequency of noise caused by the switching operation of the power device 233PD to be outside the human audible range.

[0088] The heat dissipation section 240 dissipates the heat of the power device 233PD to the outside of the power device 233PD.

[0089] 3, the heat dissipation unit 240 is a heat sink and is connected to the outer surface of the housing 110H. A through-hole 110Ha is provided in a portion of the housing 110H facing the power device 233PD, and the power device 233PD and the heat dissipation unit 240 (heat sink) are thermally coupled to each other through the through-hole 110Ha so as to enable thermal conduction.

[0090] The power device 233PD and the heat dissipation unit 240 (heat sink) are in indirect contact with each other, for example, via a heat dissipation promoting member, which is an insulator, to enable heat conduction. The heat dissipation promoting member is, for example, a heat conductive sheet containing a heat conductive filler, heat conductive grease, or the like. Alternatively, the power device 233PD and the heat dissipation unit 240 (heat sink) may be in direct contact with each other to enable heat conduction.

[0091] The heat dissipation section 240 may also be a water jacket or the like through which a refrigerant flows.

[0092] Hereinafter, the housing 110H and the heat dissipation section 240 may be collectively referred to as the "conductor section 260."

[0093] The dielectric 250 is disposed between the housing 110H and each of the power supply lines L_R4, L_S4, and L_T4 at locations where the housing 110H faces each of the power supply lines L_R4, L_S4, and L_T4. For example, one dielectric 250 is provided and disposed so as to span the area where the housing 110H faces each of the power supply lines L_R4, L_S4, and L_T4. Alternatively, three dielectrics 250 may be provided and disposed at locations where the housing 110H faces each of the power supply lines L_R4, L_S4, and L_T4.

[0094] Specifically, as shown in Fig. 3, dielectric 250 is disposed so that surface 250s1 faces inner surface 110Hs of housing 110H and surface 250s2 faces surfaces WPs1, WPs2, and WPs3 of the wiring pattern corresponding to power lines L_R4, L_S4, and L_T4. This allows dielectric 250 to increase the stray capacitances Cs_R, Cs_S, and Cs_T between housing 110H and power lines L_R4, L_S4, and L_T4, respectively, which are disposed so as to face each other, as shown in Fig. 2. Hereinafter, the combined capacitance of stray capacitances Cs_R, Cs_S, and Cs_T will be referred to as "stray capacitance Cs0."

[0095] The positional relationship between the dielectric 250 and the housing 110H in the opposing direction may be arbitrary as long as it is possible to increase the stray capacitance Cs0 to an appropriate level. For example, as shown in FIG. 3 , the dielectric 250 has a surface 250s1 in direct contact with the inner surface 110Hs of the housing 110H, and one end of the dielectric 250 on the surface 250s1 side is supported by the housing 110H. Alternatively, the dielectric 250 may be disposed so that the surface 250s1 and the inner surface 110Hs of the housing 110H are close to each other, with a minute gap between them. The minute gap is, for example, a gap of 1 mm or less.

[0096] Similarly, the positional relationship between the dielectric 250 and the power lines L_R4, L_S4, and L_T4 in the opposing direction may be arbitrary as long as it is possible to increase the stray capacitance Cs0 to an appropriate level. For example, as shown in FIG. 3 , when viewed from the inner surface 110Hs of the housing 110H, if wiring patterns corresponding to the power lines L_R4, L_S4, and L_T4 are mounted on the back surface of the substrate 220PB, the surface 250s2 of the dielectric 250 abuts against the surface of the substrate 220PB. This allows the other end of the dielectric 250 on the surface 250s2 side to be supported by the substrate 220PB, and the surface 250s2 can face the surfaces WPs1, WPs2, and WPs3 of the wiring patterns corresponding to the power lines L_R4, L_S4, and L_T4 via the substrate 220PB. In this case, the surface 250s2 of the dielectric 250 may be disposed in close proximity to the substrate 220PB, with a small gap between the surface 250s2 and the substrate 220PB. When wiring patterns corresponding to the power lines L_R4, L_S4, and L_T4 are mounted on the surface of the substrate 220PB as viewed from the inner surface 110Hs of the housing 110H, the surface 250s2 of the dielectric 250 may be in direct contact with the surfaces WPs1, WPs2, and WPs3 of the wiring pattern. In this case, the dielectric 250 may be disposed in close proximity to the surfaces WPs1, WPs2, and WPs3 of the wiring pattern, with a small gap between the surface 250s2 and the surfaces WPs1, WPs2, and WPs3 of the wiring pattern.

[0097] If a small gap exists between the dielectric 250 and either the housing 110H or the substrate 220PB including the power lines L_R4, L_S4, and L_T4, the dielectric 250 may be supported by another support member. For example, a support member is provided that supports the dielectric 250 from a direction perpendicular to the direction in which the substrate 220PB and the inner surface 110Hs of the housing 110H face each other.

[0098] The dielectric 250 has a relative permittivity of 5 or greater in a frequency band of 300 MHz (megahertz) or less, for example. This allows for a sufficient increase in stray capacitance Cs0, for example, in a frequency band (30 MHz to 300 MHz) where radiation noise is a problem under various EMI (Electromagnetic Interference) standards. Specifically, the dielectric 250 includes, for example, silicone resin or urethane. This allows the dielectric 250 to achieve a relatively high stray capacitance Cs0 in a desired frequency band, as well as relatively high shock absorption. This, for example, improves the ease of installation of the dielectric 250 during the manufacturing process. Furthermore, even if a relatively high impact is applied to the board 220PB or the housing 110H, problems with the dielectric 250 or other components supporting the dielectric 250 can be prevented.

[0099] [Common Mode Current Generated in Power Conversion Device] Next, with reference to FIGS. 4 to 6, a common mode current generated in the power conversion device 200 according to this embodiment will be described.

[0100] Fig. 4 is a diagram showing an equivalent circuit of a power conversion device 200com according to a comparative example expressed in common mode. Fig. 5 is a diagram showing an example of the relationship between frequency and impedance of each of stray capacitance and parasitic inductance. Fig. 6 is a diagram showing an equivalent circuit of an example of a power conversion device 200 expressed in common mode.

[0101] In FIG. 5, a logarithmic axis is used as the horizontal axis representing frequency.

[0102] <Common-mode current of power conversion device according to comparative example> As shown in FIG. 4, the power conversion device 200com according to the comparative example differs from the power conversion device 200 of the above-described example (FIG. 2) in that the dielectric 250 is not provided, but is the same as the power conversion device 200 of the above-described example in other respects.

[0103] A stray capacitance Cs1 exists between the power device 233PD of the inverter 230 and the heat dissipation unit 240. Therefore, a common mode voltage is generated between the power device 233PD and the heat dissipation unit 240 due to the switching operation of the power device 233PD, and a common mode current Ic may flow out to the conductor unit 260 through the stray capacitance Cs1.

[0104] The power conversion device 200com can return the common mode current Ic_ref1, which corresponds to at least a part of the common mode current Ic that has flowed into the conductor portion 260, to the inverter 230 through a bypass path in which the Y capacitor 222 is provided.

[0105] The bypass path including the Y capacitor 222 includes a parasitic inductance component of the lead wire 225 and a parasitic inductance component of the wiring pattern 222WP on the substrate 220PB.

[0106] 5, the impedance of the parasitic inductance component increases as the current frequency increases. Therefore, for example, when the power device 233PD is driven at a relatively high frequency of 20 kHz or higher, the high-frequency common-mode current Ic flows out, and it is possible that the common-mode current Ic_ref1 cannot be sufficiently drawn into the bypass path with high impedance.

[0107] Furthermore, as described above, stray capacitance Cs0 exists between housing 110H and power lines L_R4, L_S4, and L_T4, and a path exists through which common-mode current Ic is returned to inverter 230 via stray capacitance Cs0. However, as shown in Fig. 5, in the absence of dielectric 250, the impedance of stray capacitance Cs0 is relatively high. Therefore, even though the impedance of stray capacitance Cs0 decreases as the frequency increases, it is highly likely that power conversion device 200com will not be able to return common-mode current Ic to inverter 230 via stray capacitance Cs0.

[0108] Therefore, as shown in FIG. 4, the power conversion device 200com according to the comparative example may not be able to appropriately suppress the outflow of the common mode current Ic_out to the commercial power supply PS.

[0109] <Common Mode Current of Power Conversion Device According to Embodiment> In the power conversion device 200 according to this embodiment, as described above, the dielectric 250 is disposed between the housing 110H and each of the power lines L_R4, L_S4, and L_T4.

[0110] This increases the stray capacitance Cs0. Therefore, as shown in FIG. 5 , the impedance of the stray capacitance Cs0 can be reduced. Furthermore, since the bypass path through the stray capacitance Cs0 does not include a wiring pattern or lead wires, there is no increase in impedance due to parasitic inductance. As a result, the power conversion device 200 can return the common-mode current Ic_ref2 to the inverter 230 through the stray capacitance Cs0 in addition to the bypass path including the Y capacitor 222. In particular, in the bypass path through the stray capacitance Cs0, the impedance of the stray capacitance Cs0 decreases with increasing frequency, and there is no increase in impedance due to parasitic inductance components with increasing frequency. Therefore, even when the high-frequency common-mode current Ic flows into the conductor portion 260, the power conversion device 200 can sufficiently return the high-frequency common-mode current Ic_ref2 to the inverter 230 through the stray capacitance Cs0.

[0111] Therefore, as shown in FIG. 6, the power conversion device 200 can more appropriately suppress the outflow of the common mode current Ic_out to the commercial power supply PS.

[0112] [Other Embodiments] Next, other embodiments will be described.

[0113] The above-described embodiment may be modified or changed as appropriate.

[0114] For example, in the above-described embodiment, the dielectric 250 may be provided between the inner surface 110Hs of the housing 110H and the power lines L_R3, L_S3, and L_T3 instead of between the inner surface 110Hs of the housing 110H and the power lines L_R4, L_S4, and L_T4.

[0115] Furthermore, in the above-described embodiment, the dielectric 250 may be disposed so that its surface 250s2 faces the surfaces of the wiring patterns of the power lines L_P1 and L_N1 mounted on the substrate 230PB, instead of the surfaces WPs1, WPs2, and WPs3 of the wiring patterns. In this case, the surface 250s2 of the dielectric 250 may be in direct contact with the opposing surfaces of the power lines L_P1 and L_N1, or may be disposed close to the opposing surfaces of the power lines L_P1 and L_N1 with a small gap therebetween. This allows the power conversion device 200 to bypass the common-mode current at a location closer to the power device 233PD, which is a noise source. As a result, the power conversion device 200 can more appropriately suppress radiation noise caused by the common-mode current.

[0116] Furthermore, in the above-described embodiment and its modified and altered examples, the dielectric 250 may be arranged so that the surface 250s1 faces the surface of the heat dissipation unit 240 instead of the inner surface 110Hs of the housing 110H. In this case, the surface 250s1 of the dielectric 250 may be in direct contact with the facing surface of the heat dissipation unit 240, or may be arranged in close proximity to the facing surface of the heat dissipation unit 240 with a small gap therebetween. This allows the power conversion apparatus 200 to bypass the common-mode current at a location closer to the power device 233PD, which is the noise source. This allows for more appropriate suppression of radiation noise caused by the common-mode current.

[0117] Furthermore, in the above-described embodiment and its modified and altered examples, the housing 110H and the power device 233PD may be arranged so that a common mode current can flow out without passing through the heat dissipation unit 240. Specifically, the housing 110H only needs to be located close enough to the power device 233PD that a common mode current can flow out through stray capacitance. The proximity of the power device 233PD means, for example, a distance equivalent to the thickness of a heat dissipation promotion member (e.g., a heat dissipation sheet) when the power device 233PD and the heat dissipation unit 240 are in indirect contact with each other via the heat dissipation promotion member.

[0118] In the above-described embodiment and its modified and altered examples, the power conversion device 200 may supply power to the motor of the fan 117 instead of or in addition to the motor 113M of the compressor 113 to drive it.

[0119] In the above-described embodiment and its variations and modifications, the noise filter 220 and the inverter 230 may be mounted on the same substrate.

[0120] In the above-described embodiment and its modifications and variations, at least one of the smoothing capacitor 232C and the reactor 232L may be omitted, or the smoothing circuit 232 itself may be omitted.

[0121] Furthermore, in the above-described embodiment and its modified and altered examples, the commercial power supply PS may supply single-phase AC instead of three-phase AC to the power conversion device 200. In this case, the power supply lines L_R, L_S, and L_T are replaced with two power supply lines. In this case, the common mode choke coil 221 is replaced with a single-phase common mode choke coil, and the Y capacitor 222 is replaced with two Y capacitors that bypass each of the two power supply lines and the housing 110H. In this case, the dielectric 250 is installed between the inner surface 110Hs of the housing 110H and the two power supply lines upstream of the single-phase common mode choke coil or the two power supply lines downstream of the single-phase common mode choke coil.

[0122] Furthermore, in the above-described embodiment and its modified and altered examples, the power device 231PD of the rectifier circuit 231 may be a semiconductor switch. In this case, the switching operation of the power device 231PD causes a common-mode current to flow into the housing 110H through stray capacitance between the power device 231PD and the housing 110H. For example, similar to the heat sink 240 for the power device 233PD, a heat sink thermally coupled to the power device 231PD is provided, and the heat sink is connected in direct contact with the housing 110H. As a result, a common-mode voltage is applied to the stray capacitance between the power device 231PD and the heat sink, causing a common-mode current to flow into the housing 110H through the heat sink. Therefore, the power conversion device 200 can more appropriately suppress the common-mode current originating from the power device 231PD of the rectifier circuit 231 as a noise source by the action of the dielectric 250.

[0123] Furthermore, the power conversion device 200 of the above-described embodiment may be mounted on a chiller other than the air conditioner 100. In other words, the power conversion device 200 of the above-described embodiment may be mounted on any device having a refrigeration cycle.

[0124] Furthermore, the power conversion device 200 of the above-described embodiment may be mounted on a device other than a refrigerator to drive an electric motor or the like mounted on that device. For example, the power conversion device 200 of the above-described embodiment may be mounted on a vehicle to drive an electric motor or the like of the vehicle.

[0125] [Operation] Next, the operation of the electric device and the air conditioner according to this embodiment will be described.

[0126] In a first aspect of this embodiment, the electric device includes a noise filter, a first wiring portion, a second wiring portion, a conductor member, and a dielectric. The electric device is, for example, the power conversion device 200 described above. The noise filter is, for example, the noise filter 220 described above. The first wiring portion is, for example, the power lines L_R3, L_S3, and L_T3 described above. The second wiring portion is, for example, the power lines L_R4, L_S4, and L_T4 described above. The conductor member is, for example, the conductor portion 260 described above. The dielectric is, for example, the dielectric 250 described above. Specifically, the noise filter includes a common mode choke coil, the other of one end and the other end being electrically connected to a switching device. The common mode choke coil is, for example, the common mode choke coil 221 described above. The switching device is, for example, the power device 233PD described above. Furthermore, the first wiring portion is connected to one end of the common mode choke coil. The second wiring portion is connected to the other end of the common mode choke coil. The conductor member has a surface facing the first wiring portion or the second wiring portion. The dielectric is disposed between the conductor member and either the first wiring portion or the second wiring portion. The dielectric is disposed such that its first surface faces the surface of the conductor member and its second surface opposite the first surface faces the surface of either the first wiring portion or the second wiring portion. The first surface and the second surface of the dielectric are, for example, the surface 250s1 and the surface 250s2 described above. The surface of the conductor member is, for example, the inner surface 110Hs described above. The surface of either the first wiring portion or the second wiring portion is, for example, the surface WPs1, WPs2, or WPs3 described above.

[0127] This increases the stray capacitance between either the first wiring portion or the second wiring portion and the conductor member. Therefore, the electric device can return the common-mode current, which flows into the conductor member due to the common-mode voltage caused by the switching operation of the switching device, to the switching device, which is a noise source, via the stray capacitance. Furthermore, because the stray capacitance does not include inductance components such as lead wires, impedance does not increase even at high frequencies, and the electric device can sufficiently return the high-frequency common-mode current to the switching device via the stray capacitance. Therefore, the electric device can more appropriately suppress the outflow of the common-mode current to the power supply side.

[0128] Furthermore, in a second aspect of this embodiment, based on the first aspect described above, the dielectric may be arranged so that both the first surface and the surface of the conductor member, and the second surface and the surface of either one of the wiring portions are in contact.

[0129] This makes it possible to increase the stray capacitance between either the first wiring portion or the second wiring portion and the conductive member by using the dielectric.

[0130] Furthermore, in a third aspect of this embodiment, based on the first aspect described above, the dielectric may be arranged so that either the first surface and the surface of the conductor member, or the second surface and the surface of either of the wiring portions, are in contact with each other and the other is in close proximity.

[0131] This makes it possible to increase the stray capacitance between either the first wiring portion or the second wiring portion and the conductive member.

[0132] Furthermore, in a fourth aspect of this embodiment, based on the first aspect described above, the dielectric may be arranged so that both the first surface and the surface of the conductor member, and the second surface and the surface of either one of the wiring portions, are in close proximity to each other.

[0133] This makes it possible to increase the stray capacitance between either the first wiring portion or the second wiring portion and the conductive member.

[0134] In addition, in a fifth aspect of this embodiment, assuming any one of the first to fourth aspects described above, the dielectric may be arranged between the conductor member and the second wiring portion.

[0135] This allows the common-mode current to be bypassed to the second wiring section, which is closer to the switching device (the noise source) out of the first and second wiring sections, thereby more appropriately suppressing radiation noise caused by the common-mode current.

[0136] In addition, in a sixth aspect of the present embodiment, based on any one of the first to fifth aspects described above, the dielectric may have a relative dielectric constant of 5 or more in a frequency band of 300 MHz or less.

[0137] This allows the stray capacitance between either the first wiring portion or the second wiring portion and the conductor member to be sufficiently increased in the frequency band (30 MHz to 300 MHz) where radiation noise is a problem under various EMI standards, for example, so that the electrical device can properly return the common mode current that has flowed into the conductor member through the stray capacitance from the switching device, which is the noise source.

[0138] In addition, in a seventh aspect of the present embodiment, on the premise of any one of the first to sixth aspects described above, the material of the dielectric may include silicone resin or urethane.

[0139] This allows the dielectric constant of the dielectric to be set relatively large, and makes it possible to sufficiently increase the stray capacitance between either the first wiring portion or the second wiring portion and the conductor member.

[0140] In addition, in an eighth aspect of this embodiment, on the premise of any one of the first to seventh aspects described above, the dielectric may have shock absorbing properties.

[0141] This can improve the workability of attaching the dielectric during the manufacturing process, for example. Also, in the electric device, even if an impact is applied to the substrate or conductor member on which the first wiring portion and the second wiring portion are mounted, it is possible to prevent problems from occurring in the dielectric or other components connected to the dielectric.

[0142] In a ninth aspect of the present embodiment, based on any one of the first to eighth aspects, the electric device may include the switching device. The second wiring portion may be connected between the other end of the common mode choke coil and the switching device. The conductor member may be located near the switching device and have a surface facing one of the wiring portions.

[0143] This allows the electric device to more appropriately suppress the outflow of common mode current, which has flowed into the conductor member due to the common mode voltage caused by the switching operation of the switching device, to the power supply side.

[0144] In a tenth aspect of the present embodiment, based on the ninth aspect, the conductor member may include a heat dissipation member thermally coupled to the switching device. The heat dissipation member is, for example, the heat dissipation unit 240 described above.

[0145] This allows the electric device to more appropriately prevent the common mode current that has flowed into the conductor member via the heat dissipation member from flowing to the power supply side.

[0146] In an eleventh aspect of the present embodiment, based on the ninth or tenth aspect described above, the electric device may include an inverter or converter including the switching device. The inverter is, for example, the inverter circuit 233 described above. The converter is, for example, the rectifier circuit 231 described above.

[0147] This allows the electric device to more appropriately suppress the outflow of common mode current, which has flowed into the conductor member due to the common mode voltage caused by the switching operation of the switching device of the inverter or converter, to the power supply side.

[0148] In addition, in a twelfth aspect of this embodiment, assuming any one of the ninth to eleventh aspects described above, the electrical device may include a first substrate on which the noise filter is mounted, and a second substrate different from the first substrate on which the switching device is mounted.

[0149] This allows the electric device to bypass the common mode current flowing from the switching device on the second substrate to the conductive member to the first wiring portion or the second wiring portion on the first substrate by means of the stray capacitance.

[0150] In addition, in a thirteenth aspect of this embodiment, based on any one of the ninth to twelfth aspects described above, the switching device may include a switching element formed of a wide bandgap semiconductor.

[0151] This allows the electric apparatus to more appropriately suppress the outflow of common mode current, which has flowed from a switching device including a switching element formed of a wide bandgap semiconductor to a conductive member, to the power supply side.

[0152] In addition, in a fourteenth aspect of the present embodiment, on the premise of any one of the ninth to thirteenth aspects described above, the switching frequency of the switching device may be 20 kHz or more.

[0153] This allows the electrical device to more appropriately suppress the common mode current from flowing to the power supply side, even when the switching frequency of the switching device is relatively high at 20 kHz and high-frequency common mode current flows into the conductor member.

[0154] In addition, in a fifteenth aspect of this embodiment, based on any one of the ninth to fourteenth aspects described above, the switching speed of the switching device may be 10 nanoseconds or less.

[0155] This allows the electrical device to more appropriately suppress the outflow of common mode current to the power supply side, even when the switching speed of the switching device is relatively high at 10 nanoseconds or less and high-frequency common mode current flows into the conductor member.

[0156] In a sixteenth aspect of the present embodiment, an air conditioner may include the electric device according to any one of the first to fifteenth aspects. The air conditioner is, for example, the air conditioner 100 described above.

[0157] This allows the electrical device to suppress noise radiation to the outside of the air conditioner.

[0158] Although the embodiments have been described above, it will be understood that various changes in form and details can be made without departing from the spirit and scope of the claims.

[0159] Finally, this application claims priority based on Japanese Patent Application No. 2023-170144, filed on September 29, 2023, the entire contents of which are incorporated herein by reference.

[0160] REFERENCE SIGNS LIST 100 Air conditioner 110 Outdoor unit 110H Housing 110Hs Inner surface 113 Compressor 113M Motor 120 Indoor unit 130 Refrigerant path 140 Refrigerant path 200 Power conversion device 210 Power terminal block 220 Noise filter 220PB Board 221 Common mode choke coil 222 Y capacitor 222R, 222S, 222T Y capacitor 222WP Wiring pattern 225 Lead wire 230 Inverter 230PB Board 231 Rectifier circuit 232 Smoothing circuit 233 Inverter circuit 233PD Power device 240 Heat dissipation section 250 Dielectric 250s1, 250s2 Surface 260 Conductor section Cs_R, Cs_S, Cs_T Stray capacitance Cs0, Cs1 Stray capacitance L_N1 Power line L_P1 Power line L_R Power line L_R1~L_R5 Power line L_S Power line L_S1~L_S5 Power line L_T Power line L_T1~L_T5 Power line PS Commercial power supply WPs1, WPs2, WPs3 Surface

Claims

1. An electrical device comprising: a noise filter including a common mode choke coil, the other of whose ends is electrically connected to a switching device; a first wiring portion connected to one end of the common mode choke coil; a second wiring portion connected to the other end of the common mode choke coil; a conductor member having a surface facing the first wiring portion or the second wiring portion; and a dielectric disposed between the conductor member and one of the first wiring portion and the second wiring portion, the dielectric being disposed such that a first surface faces a surface of the conductor member and a second surface opposite the first surface faces a surface of one of the wiring portions.

2. The electric device according to claim 1, wherein the dielectric is arranged so that both the first surface and a surface of the conductor member, and the second surface and a surface of either one of the wiring portions are in contact with each other.

3. The electric device according to claim 1, wherein the dielectric is arranged such that one of the first surface and a surface of the conductor member, and the second surface and a surface of either one of the wiring portions are in contact with each other and adjacent to each other.

4. The electric device according to claim 1, wherein the dielectric is disposed so that both the first surface and a surface of the conductor member, and the second surface and a surface of either one of the wiring portions are in close proximity to each other.

5. The electric device according to any one of claims 1 to 4, wherein the dielectric is disposed between the conductor member and the second wiring portion.

6. The electric device according to any one of claims 1 to 5, wherein the dielectric has a relative dielectric constant of 5 or more in a frequency band of 300 MHz or less.

7. The electric device according to any one of claims 1 to 6, wherein the dielectric material includes silicone resin or urethane.

8. An electric device according to any one of claims 1 to 7, wherein the dielectric has shock absorbing properties.

9. An electric device as claimed in any one of claims 1 to 8, comprising the switching device, the second wiring portion being connected between the other end of the common mode choke coil and the switching device, and the conductor member being located in the vicinity of the switching device and having a surface facing either one of the wiring portions.

10. The electric apparatus of claim 9, wherein the conductive member includes a heat dissipation member thermally coupled to the switching device.

11. An electric apparatus as claimed in claim 9 or 10, comprising an inverter or converter including the switching device.

12. An electric device according to any one of claims 9 to 11, comprising: a first substrate on which the noise filter is mounted; and a second substrate different from the first substrate, the second substrate on which the switching device is mounted.

13. An electric apparatus according to any one of claims 9 to 12, wherein the switching device includes a switching element formed from a wide band gap semiconductor.

14. An electric device according to any one of claims 9 to 13, wherein the switching frequency of the switching device is 20 kHz or more.

15. An electric device according to any one of claims 9 to 14, wherein the switching speed of the switching device is less than 10 nanoseconds.

16. An air conditioner comprising an electrical device according to any one of claims 1 to 15.

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