Noise filters, power conversion systems, heat pump devices, passive filter boards, and active noise canceller boards

Abstract

Reduced number of replacement parts required when the active noise canceller malfunctions. [Solution] A noise filter comprising: a passive filter (40) including a common mode choke coil (41) and a capacitor (42); a detection unit (150) for detecting common mode noise generated in a power line (11) to which the passive filter is connected; an active noise canceller (180) for outputting a compensation signal to the power line or ground (12) to reduce the common mode noise based on the signal detected by the detection unit; a first circuit board (13) on which the passive filter is mounted; and a second circuit board (14) on which the components of the active noise canceller are mounted, wherein the second circuit board is fixed to the first circuit board.

Description

Technical Field

[0001] The present disclosure relates to a noise filter, a power conversion system, a heat pump device, a passive filter substrate, and an active noise canceler substrate.

Background Art

[0002] Conventionally, in a power conversion device that converts power based on on / off of a switching element, a noise reduction device that performs active filter operation is known. This noise reduction device includes noise detection means for detecting a common mode noise current, and a noise compensation current supply circuit that forms a noise compensation current in the opposite direction to the noise current in response to the noise current detected by the noise detection means and supplies this noise compensation current to a line through which the noise current of the power conversion device flows. Further, this noise reduction device includes a line filter having a passive element such as a reactor between an AC power supply and a rectifier circuit (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a noise filter that uses a passive filter including a common mode choke coil in combination with an active noise canceler, the common mode choke coil included in the passive filter is more expensive than the semiconductor components included in the active noise canceler. On the other hand, an active noise canceler including semiconductor components has a higher risk of failure than a passive filter including passive elements. Therefore, when the active noise canceler fails, if the entire noise filter is replaced for repair, the common mode choke coil will also be replaced together.

[0005] This disclosure addresses the challenge of reducing the number of replacement parts required when an active noise canceller fails. [Means for solving the problem]

[0006] The first aspect is, A passive filter (40) including a common mode choke coil (41) and a capacitor (42), A detection unit (150) for detecting common-mode noise occurring in the power line (11) to which the passive filter is connected, An active noise canceller (180) outputs a compensation signal to reduce the common-mode noise to the power line or ground (12) based on the signal detected by the detection unit, The first substrate (13) on which the passive filter is mounted, The system comprises a second substrate (14) on which the components of the active noise canceller are mounted, The second substrate is a noise filter fixed to the first substrate.

[0007] According to the first embodiment, if the active noise canceller (180) fails, the active noise canceller can be repaired by replacing the second circuit board (14) without replacing the common mode choke coil (41) provided on the first circuit board (13). This reduces the number of parts that need to be replaced.

[0008] The second aspect is a noise filter of the first aspect, The first substrate (13) is In order to superimpose the compensation signal onto the power line, a plurality of first capacitors (82) are provided, with one terminal connected to each phase of the power line, A neutral point (82a) to which the other terminals of the multiple first capacitors are commonly connected, It comprises an earth terminal (17) connected to the earth, The neutral point and the ground terminal may be a noise filter electrically connected to the second substrate (14).

[0009] The capacitance values ​​or configuration of the multiple first capacitors (82) connected to the power line often differ depending on the model of the equipment on which the noise filter is installed. According to the second embodiment, the multiple first capacitors (82) and the neutral point (82a) are provided on the first board (13), and the neutral point (82a) is electrically connected to the second board (14). By adopting such a configuration, the second board (14) can be standardized across different models.

[0010] The third aspect is a noise filter of the first aspect, The first substrate (13) is In order to superimpose the compensation signal onto the power line, a plurality of first capacitors (82) are provided, with one terminal connected to each phase of the power line, A neutral point (82a) to which the other terminals of the multiple first capacitors are commonly connected, The ground terminal (17) connected to the ground, The system includes a second capacitor (71) to which one terminal (71a) is connected to the ground terminal in order to superimpose the compensation signal onto the ground, The neutral point and the other terminal (71b) of the second capacitor may be a noise filter electrically connected to the second substrate.

[0011] The capacitance values ​​or configurations of the multiple first capacitors (82) connected to the power line often differ depending on the model of the equipment on which the noise filter is installed. The capacitance values ​​or configurations of the second capacitor (71) connected to the ground terminal also often differ depending on the model of the equipment on which the noise filter is installed. According to the third embodiment, the multiple first capacitors (82), the neutral point (82a), and the second capacitor (71) are provided on the first circuit board (13), and the neutral point (82a) and the other terminal (71b) of the second capacitor (71) are electrically connected to the second circuit board (14). By adopting such a configuration, the second circuit board (14) can be standardized across different models.

[0012] A fourth aspect is a noise filter according to the second or third aspect, The plurality of first capacitors (82) may be noise filters that also serve as the X capacitors of the passive filter.

[0013] According to the fourth aspect, the plurality of first capacitors (82) provided on the first substrate (13) can function as the X capacitors of the passive filter (40) mounted on the same first substrate (13). By sharing components, the number of components is reduced.

[0014] The fifth aspect is a noise filter according to any one of the first to fourth aspects, where all the components mounted on the second substrate (14) may be surface-mounted components.

[0015] According to the fifth aspect, since the mounting density of the components mounted on the second substrate (14) increases, the second substrate (14) can be miniaturized.

[0016] The sixth aspect is a noise filter according to any one of the first to fifth aspects, where the number of layers of the second substrate (14) may be more than the number of layers of the first substrate (13).

[0017] According to the sixth aspect, since the mounting density of the components mounted on the second substrate (14) increases, the second substrate (14) can be miniaturized.

[0018] The seventh aspect is a noise filter according to any one of the first to sixth aspects, where the second substrate (14) is provided with a plurality of electrical connection parts (20a, 20b, 20c, 20d) capable of making electrical connections with counterparts, and among the plurality of electrical connection parts, the electrical connection part with the widest area of the conductive part that contacts the counterpart may be a noise filter that electrically connects the first substrate and the second substrate.

[0019] The electrical connection part that electrically connects the first substrate (13) and the second substrate (14) can be part of a path through which a surge current due to a surge flows. According to the seventh aspect, among the plurality of electrical connection parts, the electrical connection part with the widest area of the conductive part that contacts the mating part is electrically connecting the first substrate (13) and the second substrate (14). By widening the area of the conductive part of the electrical connection part that electrically connects the first substrate (13) and the second substrate (14), the resistance of the electrical connection part to surges is improved, so failures due to surges are suppressed.

[0020] The eighth aspect is a noise filter (301) according to any one of the first to seventh aspects, and a power conversion circuit (30) that converts the input alternating current into direct current or frequency-converts it via the noise filter, and is a power conversion system.

[0021] According to the eighth aspect, a power conversion system including a noise filter (301) capable of reducing common mode noise generated by the power conversion circuit (30) can be provided.

[0022] The ninth aspect is a heat pump device including the power conversion system of the eighth aspect.

[0023] According to the ninth aspect, a heat pump device including a noise filter (301) capable of reducing common mode noise generated by the power conversion circuit (30) can be provided.

[0024] The tenth aspect is a passive filter (40) including a common mode choke coil (41) and a capacitor (43), and a passive filter substrate that is electrically connectable to an active noise canceller substrate (14) on which components of an active noise canceller (180) that outputs a compensation signal for reducing common mode noise generated in a power line (11) to which the passive filter is connected to the power line or the ground (12) are mounted. In order to superimpose the compensation signal onto the power line, a plurality of first capacitors (82) are provided, with one terminal connected to each phase of the power line, A neutral point (82a) to which the other terminals of the multiple first capacitors are commonly connected, It comprises an earth terminal (17) connected to the earth, The neutral point and the ground terminal are electrically connectable to the active noise canceller board. This is a passive filter board to which the aforementioned active noise canceller board can be fixed.

[0025] According to the tenth embodiment, similar to the second embodiment, the active noise canceller board (14) can be standardized across different models.

[0026] The 11th aspect is, It includes a passive filter (40) which includes a common mode choke coil (41) and a capacitor (43), A passive filter board electrically connectable to an active noise canceller board (14) on which components for an active noise canceller (180) that outputs a compensation signal to the power line (11) to which the passive filter is connected, which reduces common-mode noise generated in the power line (11), is mounted, In order to superimpose the compensation signal onto the power line, a plurality of first capacitors (82) are provided, each having one terminal connected to each phase of the power line. A neutral point (82a) to which the other terminals of the multiple first capacitors are commonly connected, The ground terminal (17) connected to the aforementioned ground, The system includes a second capacitor (71) to which one terminal (71a) is connected to the ground terminal in order to superimpose the compensation signal onto the ground, The neutral point and the other terminal (71b) of the second capacitor are electrically connectable to the active noise canceller board. This is a passive filter board to which the aforementioned active noise canceller board can be fixed.

[0027] According to the 11th embodiment, similar to the third embodiment, the active noise canceller board (14) can be shared between different models.

[0028] The twelfth aspect is, The system includes an active noise canceller (180) that outputs a compensation signal to the power line (11) or ground (12) to reduce common-mode noise generated in the power line (11) to which a passive filter (40) including a common-mode choke coil (41) and a capacitor (42) is connected. An active noise canceller board that can be electrically connected to a passive filter board (13) on which the passive filter is mounted, The device comprises a neutral point (86) of a DC power supply for generating the compensation signal and an output point (60a) of the compensation signal, The neutral point and the output terminal are electrically connectable to the passive filter board. This is an active noise canceller board that can be fixed to the aforementioned passive filter board.

[0029] According to the twelfth embodiment, similar to the second embodiment, the active noise canceller board can be shared across different models.

[0030] The 13th aspect is, The system includes an active noise canceller (180) that outputs a compensation signal to the power line (11) or ground (12) to reduce common-mode noise generated in the power line (11) to which a passive filter (40) including a common-mode choke coil (41) and a capacitor (42) is connected. An active noise canceller board that can be electrically connected to a passive filter board (13) on which the passive filter is mounted, The device comprises a neutral point (86) of a DC power supply for generating the compensation signal, an output point (60a) of the compensation signal, and a second capacitor (71) with one terminal connected to the output terminal for superimposing the compensation signal onto the ground. The neutral point and the other terminal of the second capacitor are electrically connectable to the passive filter board. This is an active noise canceller board that can be fixed to the aforementioned passive filter board.

[0031] According to the 13th embodiment, similar to the third embodiment, the active noise canceller board can be shared across different models. [Brief explanation of the drawing]

[0032] [Figure 1] This is a block diagram showing a first configuration example of a noise filter according to the first embodiment. [Figure 2] This figure shows an example configuration of a power conversion circuit. [Figure 3] This is a perspective view showing a first example of a configuration in which the second substrate is fixed to the first substrate. [Figure 4] This is a perspective view showing a second example of a configuration in which the second substrate is fixed to the first substrate. [Figure 5] This is a circuit diagram showing a first example of components mounted on the first substrate and the second substrate in a first configuration example of a noise filter according to the first embodiment. [Figure 6] This is a circuit diagram showing a second example of components mounted on the first substrate and the second substrate, respectively, in a first configuration example of a noise filter according to the first embodiment. [Figure 7] This is a perspective view of a first configuration example in which the first substrate and the second substrate are electrically connected. [Figure 8] This is a perspective view of a second configuration example in which the first and second substrates are electrically connected. [Figure 9] This is a perspective view of a third configuration example in which the first and second substrates are electrically connected. [Figure 10] This is a perspective view of a fourth configuration example in which the first and second substrates are electrically connected. [Figure 11] This is a perspective view of a fifth configuration example in which the first and second substrates are electrically connected. [Figure 12] This figure shows another example of the configuration of the first substrate. [Modes for carrying out the invention]

[0033] Several embodiments will be described below.

[0034] Figure 1 is a block diagram showing a first configuration example of a noise filter according to the first embodiment. The noise filter 301 shown in Figure 1 is provided in the power conversion system 1. The power conversion system 1 forward-converts or frequency-converts the AC input from the power source 10 and supplies the DC after forward conversion or the AC after frequency conversion to the load 21.

[0035] Power source 10 is an AC power source that supplies AC power. If power source 10 is a three-phase AC power source, three-phase AC power is supplied from power source 10 to the power conversion system 1. Power source 10 is, for example, a commercial power source.

[0036] When the load 21 is a DC load, the power conversion system 1 has a converter function that forward-converts the AC power supplied from the power source 10 into DC power to be supplied to the load 21. In this case, the load 21 operates on the DC power supplied from the power conversion system 1. Examples of DC loads include electronic circuits. Electronic circuits include, for example, control circuits that control the power conversion circuit 30.

[0037] When the load 21 is an AC load, the power conversion system 1 has an inverter function that converts the frequency of the AC power supplied from the power source 10 to AC power supplied to the load 21. In this case, the load 21 operates on the AC power supplied from the power conversion system 1. An example of an AC load is a motor.

[0038] The power conversion system 1 is provided, for example, in a heat pump device 200 equipped with a load 21. The heat pump device 200 is a refrigeration cycle device equipped with a compressor driven by an AC motor, which is an example of a load 21. Examples of heat pump devices 200 include air conditioning devices that harmonize the air in a target space, water heaters that heat water to supply hot water, and chillers that control and supply the temperature of a low-temperature heat transfer medium. Note that the device to which the power conversion system 1 is provided is not limited to the heat pump device 200, but may be other equipment that requires a power conversion function.

[0039] Load 21 may be a three-phase AC motor. Three-phase AC motors are used as motors to drive compressors in the refrigerant circuit of the heat pump device 200. Three-phase AC motors are, for example, concentrated winding motors such as 4-pole 6-slot or 6-pole 9-slot motors.

[0040] The power conversion system 1 includes a power conversion circuit 30 and a noise filter 301.

[0041] The power conversion circuit 30 is electrically connected to the AC power line 11. The power conversion circuit 30 is mounted on a circuit board, for example, not shown. The circuit board is a printed circuit board or the like. The power conversion circuit 30 is electrically connected to the power supply 10 via the power line 11.

[0042] The power line 11 is a path that supplies single-phase or three-phase AC power generated by the power source 10. When supplying three-phase AC power, the power line 11 includes three-phase (R-phase, S-phase, and T-phase) power lines 11r, 11s, and 11t. The power line 11 is a power line that electrically connects the power source 10 and the power conversion circuit 30.

[0043] The power conversion circuit 30 is a circuit that performs forward conversion or frequency conversion of the alternating current input via the power line 11. The power conversion circuit 30 is an inverter circuit that performs frequency conversion of the alternating current power input via the power line 11 into alternating current power supplied to the load 21, or a converter circuit that performs forward conversion into DC power supplied to the load 21.

[0044] Figure 2 shows an example configuration of a power conversion circuit. The power conversion circuit 30 shown in Figure 2 includes a circuit for driving a motor M. The power conversion circuit 30 is an inverter circuit that frequency-converts the three-phase AC power input via the power line 11 to supply three-phase AC power to a motor M, which is an example of a load 21. The power conversion circuit 30 includes a converter 102, a DC link 103, and an inverter 104 as a circuit for driving the motor M.

[0045] Converter 102 is a circuit that converts alternating current (AC) input via power line 11 to direct current (DC), for example, by converting three-phase AC to DC. Converter 102 is, for example, a diode bridge circuit in which multiple (e.g., six) diodes are connected in a bridge configuration. These diodes full-wave rectify the AC voltage input from power line 11 and convert it to a DC voltage. Converter 102 may also be a voltage conversion circuit of a different circuit type than a diode bridge circuit. Converter 102 supplies the converted DC power to inverter 104 via DC link 103.

[0046] The DC link 103 is the part to which the DC output from the converter 102 is supplied. The DC link 103 includes, for example, a pair of DC buses 111, 112 connecting the converter 102 and the inverter 104, and a capacitor 113 connected between the pair of DC buses 111, 112. The voltage Vdc of the DC link 103 is the potential difference between the pair of DC buses 111, 112 and is approximately equal to the DC voltage across the capacitor 113. The DC voltage Vdc is input to the inverter 104.

[0047] The inverter 104 is a circuit that converts DC from the DC link 103 to AC, for example, by converting DC to three-phase AC. The inverter 104 supplies the converted AC power to the motor M. The inverter 104 is a bridge circuit in which multiple (for example, six) switching elements 104a are connected in a bridge configuration. The inverter 104 converts the DC power from the DC link 103 to AC power for the motor M by turning the multiple switching elements 104a on or off according to commands S generated by a control unit (not shown).

[0048] In Figure 1, the noise filter 301 functions as an active noise canceller. The noise filter 301 detects common-mode noise generated by the power conversion circuit 30 and outputs a cancellation signal, generated based on the level of the detected common-mode noise, to the power line 11 or ground 12. By outputting the cancellation signal to the power line 11 or ground 12, the common-mode noise flowing into the power supply 10, which is electrically connected to the power line 11 and ground 12, is reduced. The cancellation signal is a signal that reduces common-mode noise and is also called a compensation signal.

[0049] Common-mode noise generated by the power conversion circuit 30 is transmitted through the load 21 or the power conversion circuit 30 and the earth 12 via stray capacitance, and then through the earth 12 and the power line 11. Common-mode noise generated by the power conversion circuit 30 is generated, for example, in conjunction with the switching operation of the switching elements of the power conversion circuit 30. The earth 12 is grounded (connected) to the ground to which the power supply 10 is grounded (connected).

[0050] The noise filter 301 according to the first embodiment is a noise reduction device that detects a common-mode noise current Ic (common-mode current) and outputs a compensation current Io, which is generated based on the level of the detected common-mode current, to the power line 11 or ground 12.

[0051] The noise filter 301 may also be a noise reduction device that detects a common-mode noise voltage Vc (common-mode voltage) using a capacitor or the like, and outputs a compensation current Io generated based on the level of the detected common-mode voltage to the power line 11 or ground 12. Alternatively, the noise filter 301 may be a noise reduction device that outputs a compensation voltage Vo generated based on the level of the detected common-mode current or common-mode voltage to the power line 11 using a transformer or the like.

[0052] The common-mode noise current Ic (common-mode current) and common-mode noise voltage Vc (common-mode voltage) are examples of common-mode noise generated by the power conversion circuit 30, respectively. The compensation current Io and compensation voltage Vo are examples of cancellation signals generated based on the detected level of common-mode noise, respectively.

[0053] The noise filter 301 according to the first embodiment includes a passive filter 40, a detection circuit 150, an active noise canceller 180, a first substrate 13, and a second substrate 14.

[0054] The passive filter 40 is a passive noise suppression means that suppresses common-mode noise. The passive filter 40 includes a common-mode choke coil 41 and a capacitor 42.

[0055] The common mode choke coil 41 is connected to the power line 11 and acts as an inductor against the common mode noise current (common mode current) flowing through the power line 11, thereby suppressing the noise current.

[0056] Capacitor 42 is a Y-capacitor connected between the power line 11 and the ground 12, and its function is to return the common-mode current that has flowed out to the ground 12 back to the power conversion circuit 30, which acts as a noise source. One end of capacitor 42 is connected to the power line 11, and the other end is connected to the ground 12.

[0057] The detection circuit 150 is an example of a detection unit that detects common-mode noise generated in the power line 11 to which the passive filter 40 is connected. The detection circuit 150 is connected to the AC power line 11 and detects common-mode noise generated in the power line 11 and the ground 12 in conjunction with the switching operation of the power conversion circuit 30. The detection circuit 150 detects the common-mode noise current Ic flowing through the power line 11 as common-mode noise generated by the power conversion circuit 30. The detection circuit 150 detects the noise current Ic on the power supply 10 side of the location of the power conversion circuit 30. The detection circuit 150 detects the common-mode noise generated by the power conversion circuit 30 by detecting the noise current Ic flowing through the power line 11 between the power supply 10 and the power conversion circuit 30. For example, the detection circuit 150 detects the noise current Ic flowing through the power line 11 between the power supply 10 and the power conversion circuit 30 using a transformer.

[0058] The detection circuit 150 is configured to detect noise current Ic using a transformer and includes, for example, a magnetic material 51 around which the main winding 53 (53r, 53s, 53t), which is part of the power line 11, is wound, and an auxiliary winding 52 wound around the magnetic material 51.

[0059] The active noise canceller 180 is connected to the detection circuit 150 and reduces common-mode noise. Based on the signal detected by the detection circuit 150, the active noise canceller 180 outputs a compensation signal to the power line 11 or ground 12 to reduce common-mode noise. The active noise canceller 180 has a filter section 91, a generation section 60, and an output section 70. The filter section 91 is optional.

[0060] The generation unit 60 generates a compensation signal (compensation current Io or compensation voltage Vo) to reduce common-mode noise based on the output voltage of the detection circuit 150. The compensation current Io or compensation voltage Vo is an example of a compensation signal to reduce common-mode noise. The generation unit 60 generates a compensation signal to be output to the power line 11 or ground 12 based on the voltage output from the detection circuit 150 according to the level of noise current Ic detected by the detection circuit 150. The output unit 70 outputs the compensation signal generated by the generation unit 60 to the power line 11 or ground 12. The generation unit 60 reduces the noise current Ic by, for example, injecting a compensation current Io at approximately the same level as the noise current Ic into the power line 11 or ground 12 via the output unit 70 in opposite phase to the noise current Ic. The output unit 70 injects the compensation current Io into the power line 11 or ground 12 via a capacitor, for example. The output unit 70 may also output the compensation voltage Vo to the power line 11 via a transformer.

[0061] The filter unit 91 is connected between the detection circuit 150 and the generation unit 60 and attenuates specific frequency components. The filter unit 91 may also be connected between the generation unit 60 and the output unit 70. The filter unit 91 may be present both between the detection circuit 150 and the generation unit 60 and between the generation unit 60 and the output unit 70.

[0062] The presence of the filter section 91 attenuates noise of specific frequency components, thereby suppressing a decrease in the compensation performance for common-mode noise due to noise of those frequency components. Examples of the filter section 91 include band-pass filters and high-pass filters.

[0063] The first board 13 is a passive filter board on which the passive filter 40 is mounted. The first board 13 is a circuit board such as a printed circuit board. A common mode choke coil 41 and a capacitor 42 are mounted on the first board 13. Components other than the passive filter 40 may be mounted on the first board 13. For example, a detection circuit 150 (more specifically, a transformer) may be mounted on the first board 13. The transformer of the detection circuit 150 may not be mounted on the board but inserted into the power line 11.

[0064] The second board 14 is an active noise canceller board on which the components of the active noise canceller 180 are mounted. The second board 14 is a circuit board such as a printed circuit board. The components of the active noise canceller 180 are not limited to all components of the active noise canceller 180, but may be some of the components of the active noise canceller 180. In other words, the second board 14 may have all the components of the active noise canceller 180 mounted on it, or it may have some of the components of the active noise canceller 180 mounted on it. For example, the generation unit 60 may be mounted on the second board 14, and the output unit 70 or filter unit 91 may be mounted on a different board from the second board 14 (for example, the first board 13). Components other than the active noise canceller 180 may be mounted on the second board 14.

[0065] The common-mode choke coil 41 included in the passive filter 40 is more expensive than the semiconductor components (e.g., active elements such as transistors and operational amplifiers) included in the active noise canceller 180. On the other hand, the active noise canceller 180, which includes active elements such as semiconductor components, has a higher risk of failure than the passive filter 40, which includes passive elements such as coils.

[0066] In the noise filter 301 according to the first embodiment, the common mode choke coil 41 is provided on a first circuit board 13, which is separate from the second circuit board 14 on which the components of the active noise canceller 180 are mounted. Therefore, if the active noise canceller 180 fails, the active noise canceller 180 can be repaired by replacing the second circuit board 14 without having to replace the common mode choke coil 41 on the first circuit board 13. In other words, the number of parts that need to be replaced when the active noise canceller 180 fails can be reduced. As a result, the normal first circuit board 13 can be used continuously after repair, and repair costs, including the cost of parts, can be reduced.

[0067] The second circuit board 14 is fixed to the first circuit board 13. The common mode choke coil 41 mounted on the first circuit board 13 is heavier than the components of the active noise canceller 180 mounted on the second circuit board 14. Therefore, the fixing of the second circuit board 14 is stabilized by fixing the lighter second circuit board 14 to the heavier first circuit board 13.

[0068] The second circuit board 14 is fixed to the first circuit board 13 so that it can be separated from the first circuit board 13 when repairing the first circuit board 13 or the second circuit board 14. The second circuit board 14 is fixed to the first circuit board 13 by fixing means 15. Examples of fixing means 15 include connectors, screws, and adhesives. If the fixing means 15 that detachably fixes the second circuit board 14 to the first circuit board 13 is a connector or a screw, the second circuit board 14 can be easily separated from the first circuit board 13 when repairing the first circuit board 13 or the second circuit board 14. This makes the replacement of parts during repair easier.

[0069] Figure 3 is a perspective view showing a first example of a configuration in which the second substrate is fixed to the first substrate. The second substrate 14 is fixed to the first substrate 13 so as to be perpendicular to the first substrate 13. Figure 4 is a perspective view showing a second example of a configuration in which the second substrate is fixed to the first substrate. The second substrate 14 is fixed to the first substrate 13 so as to be parallel to the first substrate 13. The angle at which the second substrate 14 is fixed to the first substrate 13 is not limited to 90° (right angle) or 0° (parallel), and the second substrate 14 may be fixed to the first substrate 13 such that the angle it makes with the first substrate 13 is between 0° and 90°.

[0070] Figure 5 is a circuit diagram showing a first example of components mounted on the first and second substrates in a first configuration example of the noise filter 301 according to the first embodiment. The passive filter 40 is mounted on the first substrate 13. The components of the active noise canceller 180 are mounted on the second substrate 14.

[0071] The active noise canceller 180 is an active type noise suppression means that suppresses common-mode noise. Based on the detection signal output from the auxiliary winding 52 of the detection circuit 150, the active noise canceller 180 outputs a compensation current Io to the power line 11 or ground 12 to suppress common-mode noise.

[0072] The active noise canceller 180 includes a filter section 91, a generation section 60, an output section 70, a power supply circuit 85, a coupling capacitor 82, and a drive power supply 81. The generation section 60 includes an amplification circuit 69 and a compensation circuit 87.

[0073] The filter section 91 is a circuit that passes a signal through which specific frequency components have been removed from the detection signal output from the auxiliary winding 52. The output signal from the filter section 91 is input to the generation section 60.

[0074] The filter section 91, for example, attenuates frequencies below 150 kHz among the integer multiples of the switching frequency of the power conversion circuit 30 (e.g., 10 kHz). As a result, noise from frequency components outside the compensation band below 150 kHz among the integer multiples of the switching frequency of the power conversion circuit 30 is attenuated, thereby suppressing a decrease in the compensation performance against common-mode noise due to noise of these frequency components.

[0075] The filter section 91, for example, attenuates frequencies below 150 kHz among the integer multiples of the resonant frequency of the passive filter 40. As a result, noise from frequency components outside the compensation band below 150 kHz among the integer multiples of the resonant frequency of the passive filter 40 is attenuated, thereby suppressing a decrease in the compensation performance against common-mode noise due to noise of these frequency components. The resonant frequency of the passive filter 40 is determined by the inductance of the common-mode choke coil 41 and the capacitance of the capacitor 42.

[0076] The filter section 91 is connected between the auxiliary winding 52 of the detection circuit 150 and the amplification circuit 69 of the generation section 60. The filter section 91 may also be connected between the output point 60a of the compensation signal of the generation section 60 (the interconnection point of transistors 61 and 62) and the output capacitor 71 of the output section 70.

[0077] The amplification circuit 69 amplifies the input voltage Vd of the generation unit 60. The amplification circuit 69 includes, for example, an operational amplifier 69a for amplifying the input voltage Vd.

[0078] The power supply voltage Vcc of the generation unit 60 (voltage of the drive power supply 81) is, for example, 2 / 3 or less of the DC link voltage (DC link voltage Vdc) of the power conversion circuit 30. The voltage Vcom of the common-mode noise source (specifically, the potential of the neutral point of the motor M generated when the motor M is driven by the inverter 104 of the power conversion circuit 30) changes by 1 / 3 increments. Therefore, if the power supply voltage Vcc is within ±1 / 3 of the DC link voltage Vdc, common-mode noise caused by the switching operation of the inverter 104 can be canceled out without considering the relationship between the power supply voltage Vcc and impedance.

[0079] The signal output from the amplification circuit 69 is a signal representing the waveform of the compensation current or compensation voltage, and is input to the compensation circuit 87. The signal representing the waveform of the compensation current or compensation voltage is a signal that indicates the amplitude and phase for each frequency in the waveform of the compensation current or compensation voltage output from the compensation circuit 87. For example, the signal representing the waveform of the compensation current or compensation voltage output from the amplification circuit 69 is a current or voltage waveform signal that has the same phase for each frequency and a smaller amplitude compared to the waveform of the compensation current or compensation voltage output from the compensation circuit 87.

[0080] The compensation circuit 87 amplifies the signal output from the amplification circuit 69 and outputs a compensation current or compensation voltage. The compensation circuit 87 includes transistors 61, 62, diodes 63, 64, resistors 65, 66, and diodes 67, 68.

[0081] Transistor 61 is connected between one end of the drive power supply 81 and the output capacitor 71 of the output unit 70. Transistor 62 is connected between the other end of the drive power supply 81 and the output capacitor 71 of the output unit 70.

[0082] As shown in Figure 5, in this example, transistor 61 is a PNP type and transistor 62 is an NPN type, and transistors 61 and 62 have opposite polarities. As a result, transistors 61 and 62 form a push-pull circuit, and the push-pull circuit functions as an amplifier.

[0083] The bases of transistors 61 and 62 are connected to one end of the auxiliary winding 52 via diodes 67 and 68 and an amplification circuit 69, while the interconnection point (output point 60a) of transistors 61 and 62 is connected to the other end of the auxiliary winding 52 via the amplification circuit 69. As a result, transistors 61 and 62 operate in opposite directions.

[0084] Diodes 63 and 64 are connected in antiparallel to transistors 61 and 62, respectively, to protect them.

[0085] The output unit 70 connects the compensation circuit 87 and the ground 12, and outputs (also referred to as "injecting") the compensation current or compensation voltage output from the compensation circuit 87 into the path through which the common-mode current flows. The output unit 70 includes an output capacitor 71.

[0086] The output capacitor 71 has one end connected to the interconnection point (output point 60a) of transistors 61 and 62 of the compensation circuit 87, and the other end connected to ground 12.

[0087] The power supply circuit 85 is connected to the drive power supply 81. The power supply circuit 85 includes capacitors 83 and 84.

[0088] Capacitors 83 and 84 are connected in series. The series connection of capacitors 83 and 84 is connected in parallel to the drive power supply 81 and the compensation circuit 87. The midpoint (neutral point 86) of capacitors 83 and 84 is connected to the coupling capacitor 82.

[0089] The coupling capacitor 82 has one end connected to the power line 11 and the other end connected to the midpoint (neutral point 86) between capacitors 83 and 84.

[0090] The drive power supply 81 supplies DC drive power to the generation unit 60.

[0091] The drive power supply 81 may be a DC power supply capable of supplying DC to the generation unit 60 on its own, or it may be a capacitor whose power supply voltage is the DC voltage of the DC link 103 of the power conversion circuit 30.

[0092] Next, referring to Figure 5, the operation of the generation unit 60 will be explained.

[0093] The detection circuit 150 detects common-mode noise in the power line 11 and drives transistors 61 and 62 via the amplification circuit 69. Specifically, the input voltage Vd corresponding to the detection signal output from the auxiliary winding 52 of the detection circuit 150 is amplified by the amplification circuit 69 and input to the bases of transistors 61 and 62.

[0094] When a common-mode noise current Ic flows in the direction of the arrow in Figure 5, transistor 61 is turned on. In this case, the compensation current Io is supplied from the drive power supply 81 and flows through a path from the positive terminal of the drive power supply 81, through capacitor 84, coupling capacitor 82, power supply 10, output capacitor 71, and transistor 61, to the negative terminal of the drive power supply 81. In other words, the compensation current Io flows in the opposite direction to the arrow in Figure 5. As a result, the compensation current Io is subtracted from the common-mode current Ic, and the reduced common-mode current Ig flows to the power supply 10.

[0095] Furthermore, if the common-mode current Ic flows in the opposite direction to the arrow in Figure 5, transistor 62 is turned on. In this case, the compensation current Io is supplied from the drive power supply 81 and flows through a current path from the positive terminal of the drive power supply 81, through transistor 62, output capacitor 71, power supply 10, coupling capacitor 82, and capacitor 83, to the negative terminal of the drive power supply 81. As a result, the compensation current Io is subtracted from the common-mode current Ic, and a reduced common-mode current Ig flows to the power supply 10 in the opposite direction to the arrow in Figure 5.

[0096] As described above, the compensation current Io flows through the compensation circuit 87. Therefore, when the compensation current or compensation voltage is output, the current supplied from the drive power supply 81 is greater in the compensation circuit 87 than in the amplification circuit 69.

[0097] In this way, the generation unit 60 can suppress the common-mode current Ig flowing to the power supply 10 by outputting a compensation current Io to the path through which the common-mode current Ic flows. Therefore, for example, the generation unit 60 can suppress situations in which common-mode noise current flows out to peripheral equipment through the power supply 10 and affects it.

[0098] The noise filter 301 shown in Figure 5 comprises a first substrate 13 on which a passive filter 40 is mounted, and a second substrate 14 on which components for an active noise canceller 180 are mounted. In Figure 5, the outlines of the first substrate 13 and the second substrate 14 are shown with thick lines, and the state in which the second substrate 14 is superimposed on the first substrate 13 in a plan view is shown for convenience in the circuit diagram. The outlines of each substrate can be arbitrary.

[0099] The first circuit board 13 includes a plurality of coupling capacitors 82, one terminal of which is connected to each phase of the power line 11; a neutral point 82a, to which the other terminals of the plurality of coupling capacitors 82 are commonly connected; a connection terminal 16 connected to the neutral point 82a; and a ground terminal 17 connected to the ground 12. The coupling capacitors 82 are an example of a plurality of first capacitors, one terminal of which is connected to each phase of the power line, in order to superimpose a compensation signal onto the power line.

[0100] The neutral point 82a and the ground terminal 17 are electrically connected to the second board 14. The neutral point 82a on the first board 13 is electrically connected to the neutral point 86 of the power supply circuit 85 on the second board 14 via a connection terminal 16 on the first board 13. The ground terminal 17 on the first board 13 is electrically connected to one terminal 71a of the output capacitor 71 of the output section 70 on the second board 14.

[0101] A capacitor may be inserted in series with the wiring connecting the neutral point 82a and the connection terminal 16, and the neutral point 82a may be electrically connected to the second substrate 14 via the capacitor. The capacitor inserted in series with the wiring connecting the neutral point 82a and the connection terminal 16 may include multiple capacitors connected in series.

[0102] A capacitor may be inserted in series with the wiring connecting the connection terminal 16 and the neutral point 86. The capacitor inserted in series with the wiring connecting the connection terminal 16 and the neutral point 86 may include multiple capacitors connected in series.

[0103] Since the noise conditions can vary depending on the equipment on which the noise filter 301 is installed, the capacitance value or configuration of the coupling capacitor 82 connected to the power line 11 often differs depending on the model of equipment on which the noise filter 301 is installed. Similarly, the filter characteristics or configuration of the passive filter 40 connected to the power line 11 often differ depending on the model of equipment on which the noise filter 301 is installed. On the other hand, the components of the active noise canceller 180 rarely differ depending on the model of equipment on which the noise filter 301 is installed, and can be standardized across different models.

[0104] In the example shown in Figure 5, the coupling capacitor 82 and neutral point 82a are located on the first board 13, where the passive filter 40 is mounted, rather than on the second board 14, where the active noise canceller 180 components are mounted. The neutral point 82a is electrically connected to the neutral point 86 of the second board 14 via the connection terminal 16. This configuration allows the second board 14 to be shared across different models, while the coupling capacitor 82 and passive filter 40, whose characteristic values ​​may vary between different models, can be consolidated onto the first board 13. This configuration reduces the manufacturing or management costs of the second board 14.

[0105] Figure 6 is a circuit diagram showing a second example of components mounted on the first and second substrates in a first configuration example of the noise filter 301 according to the first embodiment. In Figure 6, the explanation of the configuration, operation, and effects, which are the same as in the first example in Figure 5, is omitted by referring to the explanation above. The example shown in Figure 6 differs from the example shown in Figure 5 in that the output section 70 is provided on the first substrate 13.

[0106] The first circuit board 13 includes an output capacitor 71, one of which terminals 71a is connected to the ground terminal 17, and a connection terminal 18 connected to the other terminal 71b of the output capacitor 71. The output capacitor 71 is an example of a second capacitor, one of which is connected to the ground terminal, in order to superimpose the compensation signal onto the ground. The output capacitor 71 may also include multiple capacitors connected in series.

[0107] The neutral point 82a is electrically connected to the second substrate 14, as in the first example. The ground terminal 17 provided on the first substrate 13 is electrically connected to one terminal 71a of the output capacitor 71 of the output unit 70 provided on the first substrate 13. The other terminal 71b of the output capacitor 71 is electrically connected to the output point 60a of the generation unit 60 provided on the second substrate 14 via a connection terminal 18 provided on the first substrate 13.

[0108] A capacitor may be inserted in series with the wiring connecting the other terminal 71b and the connection terminal 18, and the other terminal 71b may be electrically connected to the second board 14 via the capacitor. The capacitor inserted in series with the wiring connecting the other terminal 71b and the connection terminal 18 may include multiple capacitors connected in series.

[0109] A capacitor may be inserted in series with the wiring connecting the connection terminal 18 and the output point 60a, and the other terminal 71b may be electrically connected to the output point 60a of the second board 14 via the capacitor.

[0110] Since the noise situation can vary depending on the equipment on which the noise filter 301 is installed, the capacitance value or configuration of the output capacitor 71 connected to ground 12 via ground terminal 17 often differs depending on the model of equipment on which the noise filter 301 is installed. On the other hand, the components of the active noise canceller 180 rarely differ depending on the model of equipment on which the noise filter 301 is installed, and can be standardized across different models.

[0111] In the example shown in Figure 6, the coupling capacitor 82, neutral point 82a, and output capacitor 71 are located on the first board 13, where the passive filter 40 is mounted, rather than on the second board 14, where the active noise canceller 180 components are mounted. The neutral point 82a is electrically connected to the neutral point 86 of the second board 14 via a connection terminal 16, and the other terminal 71b of the output capacitor 71 is electrically connected to the output point 60a of the second board 14 via a connection terminal 18. By adopting this configuration, the second board 14 can be standardized across different models, while the coupling capacitor 82, passive filter 40, and output capacitor 71, whose characteristic values ​​may vary between different models, can be consolidated onto the first board 13. This configuration reduces the manufacturing or management costs of the second board 14.

[0112] In Figures 5 and 6, the passive filter 40 may also have an X capacitor with the same configuration as the coupling capacitor 82, separate from the coupling capacitor 82. However, the coupling capacitor 82 may also serve as the X capacitor within the passive filter 40. The coupling capacitor 82 provided on the first board 13 can function as the X capacitor of the passive filter 40 mounted on the same first board 13. By standardizing components, the number of components is reduced, thus achieving cost reduction.

[0113] All components mounted on the second substrate 14 may be surface-mount components. This increases the mounting density of components on the second substrate 14, allowing for miniaturization of the second substrate 14. If all components mounted on the second substrate 14 are surface-mount components compatible with the reflow process, the flow process can be reduced compared to a configuration where flow-process compatible components are mounted on the second substrate 14, resulting in cost reduction.

[0114] If the number of layers of the second substrate 14 is greater than the number of layers of the first substrate 13, the mounting density of components mounted on the second substrate 14 increases, allowing the second substrate 14 to be miniaturized. The first substrate 13 may be a multilayer substrate with fewer layers than the multilayer second substrate 14, or a single-layer substrate with fewer layers than the multilayer second substrate 14. The number of layers of the second substrate 14 may be the same as the number of layers of the first substrate 13.

[0115] Figure 7 is a perspective view of a first configuration example in which the first substrate and the second substrate are electrically connected. The second substrate 14 is provided with a plurality of electrical connection parts, each having a conductive part that can be electrically connected to a contacting partner. The contacting partner is not limited to the first substrate 13, and may be a different component from the first substrate 13.

[0116] In Figure 7, multiple electrical connection parts 20a, 20b, and 20c are provided on the second substrate 14. Electrical connection part 20a has a conductive part 19a that can be electrically connected to the above-mentioned connection terminal 16 provided in the through-hole 22a of the first substrate 13. Electrical connection part 20b has a conductive part 19b that can be electrically connected to the above-mentioned ground terminal 17 or connection terminal 18 provided in the through-hole 22b of the first substrate 13. Electrical connection part 20c has a conductive part 19c that can be electrically connected to a different component (not shown) from the first substrate 13.

[0117] For example, the electrical connection part 20a is a female thread that can be fastened to a male thread (not shown) corresponding to a connection terminal 16 that penetrates the through-hole 22a, and the conductive part 19a is a contact surface that contacts the male thread (not shown). For example, the electrical connection part 20b is a female thread that can be fastened to a male thread (not shown) corresponding to an earth terminal 17 or connection terminal 18 that penetrates the through-hole 22b, and the conductive part 19b is a contact surface that contacts the male thread (not shown). The electrical connection parts 20a and 20b may function as components that realize the above-described fixing means 15.

[0118] For example, the electrical connection part 20c is a connector that can be connected to a connector (not shown) different from the first substrate 13, and the conductive part 19c is a pin that contacts that connector (not shown).

[0119] The electrical connections 20a and 20b that electrically connect the first substrate 13 and the second substrate 14 can be part of the path through which not only the compensation current generated by the active noise canceller 180 but also the surge current caused by surges flows. For example, in Figure 5 or Figure 6, the surge current flows through the path of the power supply 10, power line 11, coupling capacitor 82, connection terminal 16, capacitor 83, diode 63, output capacitor 71, ground terminal 17, and ground 12.

[0120] In Figure 7, among the multiple electrical connection parts 20a, 20b, and 20c, the electrical connection part with the largest conductive area (in this case, electrical connection parts 20a and 20b) electrically connects the first substrate 13 and the second substrate 14. Conductive parts 19a and 19b have the largest surface area among conductive parts 19a, 19b, and 19c. The surface area of ​​conductive parts 19a and 19b is set to be large enough to allow surge currents larger than the compensation current to flow. By increasing the area of ​​the conductive parts 19a and 19b of the electrical connection parts 20a and 20b that electrically connect the first substrate 13 and the second substrate 14, the surge resistance of the electrical connection parts 20a and 20b is improved, thereby suppressing failures due to surges.

[0121] Figure 8 is a perspective view of a second configuration example in which the first and second substrates are electrically connected. In the second configuration example, the explanation of the configuration, operation, and effects, which are the same as in the above-described example, will be omitted by referring to the above-described explanation. The second configuration example shown in Figure 8 differs from the first configuration example shown in Figure 7 in that it does not have an electrical connection part 20c.

[0122] In Figure 8, among the multiple electrical connection points 20a and 20b, the electrical connection point with the largest conductive area (in this case, electrical connection points 20a and 20b) electrically connects the first substrate 13 and the second substrate 14. If the conductive area of ​​each of the multiple electrical connection points is the same, then those multiple electrical connection points are considered to be the electrical connection point with the largest conductive area.

[0123] Figure 9 is a perspective view of a third configuration example in which the first and second substrates are electrically connected. In this third configuration example, the explanation of the configuration, operation, and effects, which are the same as those in the above-described configuration examples, will be omitted by referring to the above-described explanation.

[0124] In Figure 9, multiple electrical connection parts 20a and 20b are provided on the second substrate 14. Electrical connection part 20a has a conductive part 19a that can be electrically connected to multiple pins 23a provided on the first substrate 13. Electrical connection part 20b has a conductive part 19b that can be electrically connected to multiple pins 23b provided on the first substrate 13. The multiple pins 23a include the pins of the connection terminal 16 and the pins of the ground terminal 17, or include the pins of the connection terminal 16 and the pins of the connection terminal 18.

[0125] For example, the electrical connection part 20a is a female connector that can be connected to a male connector having a plurality of pins 23a, and the conductive part 19a is a contact surface that contacts the plurality of pins 23a. Similarly, the electrical connection part 20b is a female connector that can be connected to a male connector having a plurality of pins 23b, and the conductive part 19b is a contact surface that contacts the plurality of pins 23b.

[0126] In Figure 9, among the multiple electrical connection parts 20a and 20b, the electrical connection part with the largest conductive area (in this case, electrical connection part 20a) electrically connects the first substrate 13 and the second substrate 14. Conductive part 19a has the largest surface area among conductive parts 19a and 19b. The surface area of ​​conductive part 19a is set to be large enough to allow a surge current larger than the compensation current to flow. By increasing the area of ​​the conductive part 19a of the electrical connection part 20a that electrically connects the first substrate 13 and the second substrate 14, the surge resistance of the electrical connection part 20a is improved, and failure due to surges is suppressed. In Figure 9, electrical connection part 20b also electrically connects the first substrate 13 and the second substrate 14, but since it is not a path through which surge current flows, pin 23b can be thinner than pin 23a.

[0127] Figure 10 is a perspective view of a fourth configuration example in which the first substrate and the second substrate are electrically connected. In this fourth configuration example, the explanation of the configuration, operation, and effects, which are the same as those in the above-described configuration examples, will be omitted by referring to the above-described explanation.

[0128] In Figure 10, multiple electrical connection parts 20a, 20b, and 20c are provided on the second substrate 14. Electrical connection part 20a has a conductive part 19a that can be electrically connected to the above-mentioned connection terminal 16 provided in the through-hole 22a of the first substrate 13. Electrical connection part 20b has a conductive part 19b that can be electrically connected to the above-mentioned ground terminal 17 or connection terminal 18 provided in the through-hole 22b of the first substrate 13. Electrical connection part 20c has a conductive part 19c that can be connected to a connection terminal provided in the through-hole 22c of the first substrate 13. Electrical connection part 20d has a conductive part 19d that can be electrically connected to a different component (not shown) from the first substrate 13.

[0129] For example, the electrical connection part 20a is a metal spacer having a female thread that can be fastened to a male thread (not shown) corresponding to a connection terminal 16 that passes through the through-hole 22a, and the conductive part 19a is a contact surface that contacts the male thread (not shown). For example, the electrical connection part 20b is a metal spacer having a female thread that can be fastened to a male thread (not shown) corresponding to an earth terminal 17 or connection terminal 18 that passes through the through-hole 22b, and the conductive part 19b is a contact surface that contacts the male thread (not shown). For example, the electrical connection part 20c is a metal spacer having a female thread that can be fastened to a male thread (not shown) corresponding to a connection terminal 18 that passes through the through-hole 22c, and the conductive part 19c is a contact surface that contacts the male thread (not shown). The electrical connection parts 20a, 20b, and 20c may function as components that realize the above-described fixing means 15.

[0130] For example, the electrical connection part 20d is a connector that can be connected to a connector (not shown) different from the first substrate 13, and the conductive part 19d is a pin that contacts that connector (not shown).

[0131] The electrical connections 20a and 20b that electrically connect the first substrate 13 and the second substrate 14 can be part of the path through which not only the compensation current generated by the active noise canceller 180 but also the surge current caused by surges flows. In Figure 10, among the multiple electrical connections 20a, 20b, 20c, and 20d, the electrical connection with the largest conductive area (in this case, electrical connections 20a and 20b) electrically connects the first substrate 13 and the second substrate 14. Conductive parts 19a and 19b have the largest surface area among conductive parts 19a, 19b, 19c, and 19d. The surface area of ​​conductive parts 19a and 19b is set to be large enough to allow a surge current larger than the compensation current to flow. By increasing the area of ​​the conductive parts 19a and 19b of the electrical connection parts 20a and 20b that electrically connect the first substrate 13 and the second substrate 14, the surge resistance of the electrical connection parts 20a and 20b is improved, thereby suppressing failures caused by surges.

[0132] Figure 11 is a perspective view of a fifth configuration example in which the first and second substrates are electrically connected. In the fifth configuration example, explanations of the configuration, operation, and effects similar to those of the above-described configuration examples are omitted by referring to the above-described explanations. The fifth configuration example shown in Figure 11 differs from the tenth configuration example shown in Figure 10 in the electrical connection part 20c. The configuration of the electrical connection part 20c and conductive part 19c in Figure 11 may be the same as the configuration of the electrical connection part 20b and conductive part 19b in Figure 9, and the pin 23c in Figure 11 may be the same as the pin 23b in Figure 9.

[0133] The electrical connections 20a and 20b that electrically connect the first substrate 13 and the second substrate 14 can be part of the path through which not only the compensation current generated by the active noise canceller 180 but also the surge current caused by surges flows. In Figure 11, among the multiple electrical connections 20a, 20b, 20c, and 20d, the electrical connection with the largest conductive area (in this case, electrical connections 20a and 20b) electrically connects the first substrate 13 and the second substrate 14. Conductive parts 19a and 19b have the largest surface area among conductive parts 19a, 19b, 19c, and 19d. The surface area of ​​conductive parts 19a and 19b is set to be large enough to allow a surge current larger than the compensation current to flow. By increasing the area of ​​the conductive parts 19a and 19b of the electrical connection parts 20a and 20b that electrically connect the first substrate 13 and the second substrate 14, the surge resistance of the electrical connection parts 20a and 20b is improved, thereby suppressing failures caused by surges.

[0134] Figure 20 shows another example of the configuration of the first board. The passive filter 40 may be mounted on the same board as the power conversion board 106 on which the power conversion circuit 30 (converter 102, DC link 103, and inverter 104) is mounted. In other words, the first board 13 on which the passive filter 40 is mounted may be the same as the power conversion board 106. The power conversion circuit 30 may also have a control circuit 105 that controls the inverter 104 mounted on it.

[0135] As described above, embodiments have been explained, but these embodiments are presented as examples only, and the present invention is not limited by these embodiments. The above embodiments can be implemented in various other forms, and various combinations, omissions, substitutions, and modifications are possible without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. [Explanation of symbols]

[0136] 1. Power Conversion System 10 Power supply 11 Power lines 12 Earth 13 First board 14 Second board 15 Fixing means 16 Connection terminals 17. Ground terminal 18 Connection terminals 19 Conductive parts 20 Electrical connection part 21 load 22a, 22b, 22c Through-hole 23a, 23b, 23c pins 30 Power Conversion Circuit 40 Passive Filters 41 Common Mode Choke Coil 42 Capacitors 51 Magnetic material 52 Auxiliary winding 53,53r,53s,53t Main winding 55 First Impedance Element 56 Second Impedance Element 60 Generation part 60a output point 69 Amplifier Circuit 70 Output section 71 Output Capacitor 72 Output Transformer 81 Power supply 82 Coupling Capacitors 82a Neutral point 83,84 Capacitors 85 Power supply circuit 86 Neutral point 87 Compensation circuit 91 Filter section 105 Control circuit 106 Power Conversion Board 150 detection circuit 180 Active Noise Canceller 200 Heat pump equipment 301,302 Noise Filter

Claims

1. A passive filter (40) including a common-mode choke coil (41) and a capacitor (42), A detection unit (150) for detecting common-mode noise occurring in the power line (11) to which the passive filter is connected, An active noise canceller (180) outputs a compensation signal to reduce the common-mode noise to the power line or ground (12) based on the signal detected by the detection unit, The first substrate (13) on which the passive filter is mounted, The system comprises a second substrate (14) on which the components of the active noise canceller are mounted, The second substrate is a noise filter fixed to the first substrate.

2. The first substrate (13) is In order to superimpose the compensation signal onto the power line, a plurality of first capacitors (82) are provided, with one terminal connected to each phase of the power line, A neutral point (82a) to which the other terminals of the multiple first capacitors are commonly connected, It includes an earth terminal (17) connected to the earth, The noise filter according to claim 1, wherein the neutral point and the ground terminal are electrically connected to the second substrate (14).

3. The first substrate (13) is In order to superimpose the compensation signal onto the power line, a plurality of first capacitors (82) are provided, with one terminal connected to each phase of the power line, A neutral point (82a) to which the other terminals of the multiple first capacitors are commonly connected, The ground terminal (17) connected to the ground, The system includes a second capacitor (71) to which one terminal (71a) is connected to the ground terminal in order to superimpose the compensation signal onto the ground, The noise filter according to claim 1, wherein the neutral point and the other terminal (71b) of the second capacitor are electrically connected to the second substrate.

4. The noise filter according to claim 2 or 3, wherein the plurality of first capacitors (82) also serve as the X capacitors of the passive filter.

5. The noise filter according to any one of claims 1 to 3, wherein all components mounted on the second substrate (14) are surface-mount components.

6. The noise filter according to any one of claims 1 to 3, wherein the number of layers of the second substrate (14) is greater than the number of layers of the first substrate (13).

7. The second substrate (14) is provided with a plurality of electrical connection parts (20a, 20b, 20c, 20d) that can be electrically connected to a contacting object. The noise filter according to any one of claims 1 to 3, wherein, among the plurality of electrical connection parts, the electrical connection part with the largest area of ​​conductive part that contacts the contacting object electrically connects the first substrate and the second substrate.

8. A noise filter (301) according to any one of claims 1 to 3, A power conversion system comprising a power conversion circuit (30) that forward-converts or frequency-converts the AC input via the noise filter.

9. A heat pump device comprising the power conversion system described in claim 8.

10. It includes a passive filter (40) which includes a common mode choke coil (41) and a capacitor (43), A passive filter board electrically connectable to an active noise canceller board (14) on which components for an active noise canceller (180) that outputs a compensation signal to the power line (11) to which the passive filter is connected, which reduces common-mode noise generated in the power line (11), is mounted, In order to superimpose the compensation signal onto the power line, a plurality of first capacitors (82) are provided, with one terminal connected to each phase of the power line, A neutral point (82a) to which the other terminals of the multiple first capacitors are commonly connected, It includes an earth terminal (17) connected to the earth, The neutral point and the ground terminal are electrically connectable to the active noise canceller board. A passive filter board on which the aforementioned active noise canceller board can be fixed.

11. It includes a passive filter (40) which includes a common mode choke coil (41) and a capacitor (43), A passive filter board electrically connectable to an active noise canceller board (14) on which components for an active noise canceller (180) that outputs a compensation signal to the power line (11) to which the passive filter is connected, which reduces common-mode noise generated in the power line (11), is mounted, In order to superimpose the compensation signal onto the power line, a plurality of first capacitors (82) are provided, each having one terminal connected to each phase of the power line. A neutral point (82a) to which the other terminals of the multiple first capacitors are commonly connected, The ground terminal (17) connected to the ground, The system includes a second capacitor (71) to which one terminal (71a) is connected to the ground terminal in order to superimpose the compensation signal onto the ground, The neutral point and the other terminal (71b) of the second capacitor are electrically connectable to the active noise canceller board. A passive filter board on which the aforementioned active noise canceller board can be fixed.

12. The system includes an active noise canceller (180) that outputs a compensation signal to the power line (11) or ground (12) to reduce common-mode noise generated in the power line (11) to which a passive filter (40) including a common-mode choke coil (41) and a capacitor (42) is connected. An active noise canceller board that can be electrically connected to a passive filter board (13) on which the passive filter is mounted, The device comprises a neutral point (86) of a DC power supply for generating the compensation signal and an output point (60a) of the compensation signal, The neutral point and the output point are electrically connectable to the passive filter substrate. An active noise canceller board that can be fixed to the passive filter board.

13. The system includes an active noise canceller (180) that outputs a compensation signal to the power line (11) or ground (12) to reduce common-mode noise generated in the power line (11) to which a passive filter (40) including a common-mode choke coil (41) and a capacitor (42) is connected. An active noise canceller board that can be electrically connected to a passive filter board (13) on which the passive filter is mounted, The system comprises a neutral point (86) of a DC power supply for generating the compensation signal, an output point (60a) of the compensation signal, and a second capacitor (71) with one terminal connected to the output point in order to superimpose the compensation signal onto the ground. The neutral point and the other terminal of the second capacitor are electrically connectable to the passive filter board. An active noise canceller board that can be fixed to the passive filter board.

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