Noise filter, power conversion system, heat pump device, passive filter substrate, and active noise canceller substrate

Abstract

A noise filter according to the present invention comprises a passive filter (40) that includes a common-mode choke coil (41) and a capacitor (42), a detection unit (150) that detects common-mode noise that occurs at a power line (11) to which the passive filter is connected, an active noise canceller (180) that outputs a compensation signal that reduces the common-mode noise to the power line or a ground (12) on the basis of a signal detected by the detection unit, a first substrate (13) on which the passive filter is installed, and a second substrate (14) on which components of the active noise canceller are installed. The second substrate is fixed to the first substrate.

Description

Noise filter, power conversion system, heat pump device, passive filter substrate, and active noise canceller substrate

[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 canceller substrate.

[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 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).

[0003] Japanese Patent Laid-Open No. 9-266677

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

[0005] An object of the present disclosure is to reduce the number of replacement parts when an active noise canceller fails.

[0006] The first embodiment is 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) that outputs 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 substrate (13) on which the passive filter is mounted; and a second substrate (14) on which the components of the active noise canceller are mounted, wherein the second substrate is 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 embodiment is a noise filter of the first embodiment, wherein the first substrate (13) comprises a plurality of first capacitors (82) to which one terminal is connected to each phase of the power line in order to superimpose the compensation signal on the power line, a neutral point (82a) to which the other terminals of the plurality of first capacitors are commonly connected, and a ground terminal (17) connected to the earth, and the neutral point and the ground terminal are electrically connected to the second substrate (14), thus forming a noise filter.

[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] A third embodiment is a noise filter of the first embodiment, wherein the first substrate (13) comprises: a plurality of first capacitors (82) whose one terminal is connected to each phase of the power line in order to superimpose the compensation signal onto the power line; a neutral point (82a) to which the other terminals of the plurality of first capacitors are commonly connected; a ground terminal (17) connected to the earth; and a second capacitor (71) whose one terminal (71a) is connected to the ground terminal in order to superimpose the compensation signal onto the earth, wherein the neutral point and the other terminal (71b) of the second capacitor are electrically connected to the second substrate, and the noise filter is such that.

[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 embodiment is a noise filter according to the second or third embodiment, wherein the plurality of first capacitors (82) also serve as the X capacitors of the passive filter.

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

[0014] The fifth embodiment is a noise filter according to any one of the first to fourth embodiments, wherein all components mounted on the second substrate (14) are surface-mount components.

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

[0016] The sixth embodiment is a noise filter according to any one of the first to fifth embodiments, wherein the number of layers of the second substrate (14) is greater than the number of layers of the first substrate (13).

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

[0018] The seventh embodiment is a noise filter according to any one embodiment of the first to sixth embodiments, wherein the second substrate (14) is provided with a plurality of electrical connection portions (20a, 20b, 20c, 20d) that can be electrically connected to a contacting object, and the electrical connection portion with the largest area of ​​conductive portion that contacts the contacting object electrically connects the first substrate and the second substrate, and is a noise filter.

[0019] The electrical connection between the first substrate (13) and the second substrate (14) can become part of the path through which surge current flows due to a surge. According to the seventh embodiment, among the multiple electrical connection parts, the electrical connection part with the largest area of ​​conductive part in contact with the contacting mater is the one that electrically connects the first substrate (13) and the second substrate (14). By increasing the area of ​​the conductive part of the electrical connection part that electrically connects the first substrate (13) and the second substrate (14), the surge resistance of the electrical connection part is improved, thereby suppressing failures due to surges.

[0020] The eighth aspect is a power conversion system comprising a noise filter (301) according to any one of the first to seventh aspects, and a power conversion circuit (30) that performs forward conversion or frequency conversion of the AC input through the noise filter.

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

[0022] The ninth embodiment is a heat pump device equipped with the power conversion system of the eighth embodiment.

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

[0024] The tenth embodiment is a passive filter board electrically connectable to an active noise canceller board (14) on which components for an active noise canceller (180) are mounted, the active noise canceller (180) having a passive filter (40) including a common mode choke coil (41) and a capacitor (43) and outputting a compensation signal to the power line (11) to which the passive filter is connected to reduce common mode noise generated in the power line (11) is the passive filter board, comprising: a plurality of first capacitors (82) to which one terminal is connected to each phase of the power line in order to superimpose the compensation signal on the power line; a neutral point (82a) to which the other terminals of the plurality of first capacitors are commonly connected; and a ground terminal (17) connected to the ground, wherein the neutral point and the ground terminal are electrically connectable to the active noise canceller board, and the active noise canceller board can be fixed to the passive filter board.

[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 eleventh embodiment is a passive filter board electrically connectable to an active noise canceller board (14) on which components for an active noise canceller (180) are mounted, the active noise canceller (180) having a passive filter (40) including a common mode choke coil (41) and a capacitor (43) and outputting a compensation signal to reduce common mode noise generated in the power line (11) to which the passive filter is connected to the power line or ground (12), the passive filter board comprising: a plurality of first capacitors (82) with one terminal connected to each phase of the power line in order to superimpose the compensation signal onto the power line; a neutral point (82a) to which the other terminals of the plurality of first capacitors are commonly connected; a ground terminal (17) connected to ground; and a second capacitor (71) with one terminal (71a) connected to the ground terminal in order to superimpose the compensation signal onto ground, wherein 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 eleventh embodiment, similar to the third embodiment, the active noise canceller board (14) can be standardized across different models.

[0028] The twelfth embodiment is an active noise canceller board that 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, and is electrically connectable to a passive filter board (13) on which the passive filter is mounted, and includes a neutral point (86) of a DC power supply for generating the compensation signal and an output point (60a) of the compensation signal, wherein the neutral point and the output terminal are electrically connectable to the passive filter board and the active noise canceller board is fixable to the 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 thirteenth embodiment is an active noise canceller board that includes an active noise canceller (180) that outputs a compensation signal to the power line (11) or ground (12) to which a passive filter (40) including a common mode choke coil (41) and a capacitor (42) is connected, which reduces common mode noise generated in the power line (11), and is electrically connectable to a passive filter board (13) on which the passive filter is mounted, and 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) to which one terminal is connected to the output terminal in order to superimpose the compensation signal on ground, wherein the neutral point and the other terminal of the second capacitor are electrically connectable to the passive filter board and are fixable to the passive filter board.

[0031] According to the 13th embodiment, similar to the third embodiment, the active noise canceller board can be standardized across different models.

[0032] This is a block diagram showing a first configuration example of a noise filter according to the first embodiment. This is a diagram showing a configuration example of a power conversion circuit. This is a perspective view showing a first example of a configuration in which the second substrate is fixed to the first substrate. This is a perspective view showing a second example of a configuration in which the second substrate is fixed to the first substrate. This is a circuit diagram showing a first example of components mounted on the first substrate and the second substrate respectively in the first configuration example of a noise filter according to the first embodiment. This is a circuit diagram showing a second example of components mounted on the first substrate and the second substrate respectively in the first configuration example of a noise filter according to the first embodiment. This is a perspective view of a first configuration example in which the first substrate and the second substrate are electrically connected. This is a perspective view of a second configuration example in which the first substrate and the second substrate are electrically connected. This is a perspective view of a third configuration example in which the first substrate and the second substrate are electrically connected. This is a perspective view of a fourth configuration example in which the first substrate and the second substrate are electrically connected. This is a perspective view of a fifth configuration example in which the first substrate and the second substrate are electrically connected. This is a diagram showing another configuration example of the first substrate.

[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 supply 10 is an AC power source that provides AC power. If power supply 10 is a three-phase AC power source, three-phase AC power is supplied from power supply 10 to the power conversion system 1. Power supply 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 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 a heat pump device 200, but may be other equipment that requires a power conversion function.

[0039] The load 21 may be a three-phase AC motor. The three-phase AC motor is used for, for example, an electric motor that drives a compressor provided in the refrigerant circuit of the heat pump device 200. The three-phase AC motor is, for example, a concentrated winding motor such as a 4-pole 6-slot or 6-pole 9-slot motor.

[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, for example, a substrate not shown. The substrate is a circuit board such as a printed circuit board. 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 for supplying single-phase or three-phase AC power generated by the power supply 10. When the power line 11 supplies three-phase AC power, it includes three-phase (R-phase, S-phase, and T-phase) power lines 11r, 11s, and 11t. The power line 11 is a power supply line that electrically connects between the power supply 10 and the power conversion circuit 30.

[0043] The power conversion circuit 30 is a circuit that converts the AC input via the power line 11 into a forward conversion or frequency conversion. The power conversion circuit 30 is an inverter circuit that converts the AC power input via the power line 11 into AC power supplied to the load 21 or a converter circuit that forward-converts it into DC power supplied to the load 21.

[0044] FIG. 2 is a diagram showing a configuration example of the power conversion circuit. The power conversion circuit 30 shown in FIG. 2 includes a circuit for driving the motor M. The power conversion circuit 30 is an inverter circuit that frequency-converts the three-phase AC power input via the above power line 11 into three-phase AC power supplied to the motor M, which is an example of the 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 (for example, 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 and 112 connecting the converter 102 and the inverter 104, and a capacitor 113 connected between the pair of DC buses 111 and 112. The voltage Vdc of the DC link 103 is the potential difference between the pair of DC buses 111 and 112 and is approximately equal to the DC voltage generated 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 a plurality (for example, six) of 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 plurality of switching elements 104a on or off according to commands S generated by a control unit (not shown).

[0048] In FIG. 1, the noise filter 301 has the function of 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 the ground 12. By outputting the cancellation signal to the power line 11 or the ground 12, the common-mode noise flowing out to the power supply 10 electrically connected to the power line 11 and the ground 12 is reduced. The cancellation signal is a signal for reducing common-mode noise and is also referred to as a compensation signal.

[0049] The common-mode noise generated by the power conversion circuit 30 is transmitted through the floating capacitance between the load 21 or the power conversion circuit 30 and the ground 12 to the ground 12 and the power line 11. The common-mode noise generated by the power conversion circuit 30 is generated, for example, along with the switching operation of the switching element of the power conversion circuit 30. The ground 1 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 generated based on the level of the detected common-mode current to the power line 11 or the ground 12.

[0051] Note that the noise filter 301 may be a noise reduction device that detects a common-mode noise voltage Vc (common-mode voltage) by 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 the ground 12. The noise filter 301 may also 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 by 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 windings 53 (53r, 53s, 53t), which are part of the power line 11, are 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 the 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 the filter unit 91 may be mounted on a board other than 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 (for example, 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 provided 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 repairs 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 than 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 the compensation current or compensation voltage output from the compensation circuit 87 to the path through which the common-mode current flows (also referred to as "injecting" it). The output unit 70 includes an output capacitor 71.

[0086] One end of the output capacitor 71 is connected to the interconnection point (output point 60a) of transistors 61 and 62 of the compensation circuit 87, and the other end is 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 independently, or it may be a capacitor that uses the DC voltage of the DC link 103 of the power conversion circuit 30 as its power supply voltage.

[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 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, when 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 of 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 provided on the first board 13 is electrically connected to the neutral point 86 of the power supply circuit 85 provided on the second board 14 via a connection terminal 16 provided on the first board 13. The ground terminal 17 provided on the first board 13 is electrically connected to one terminal 71a of the output capacitor 71 of the output unit 70 provided 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 on which the passive filter 40 is mounted, rather than on the second board 14 on which 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. By adopting this configuration, the second board 14 can be standardized 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, will be 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 with one terminal 71a 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 with one terminal connected to the ground terminal, which is connected to the ground, 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 the ground 12 via the ground terminal 17 often differs depending on the model of the 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 the 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 on which the passive filter 40 is mounted, rather than on the second board 14 on which 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 include 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 substrate 13 can function as the X capacitor of the passive filter 40 mounted on the same first substrate 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, but 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 member (not shown) different from the first substrate 13.

[0117] For example, the electrical connection portion 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 portion 19a is a contact surface that contacts the male thread (not shown). For example, the electrical connection portion 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 portion 19b is a contact surface that contacts the male thread (not shown). The electrical connection portions 20a and 20b may function as components that realize the above-mentioned 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 the 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 a surge 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 substrate and the second substrate 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 designated as 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 substrate and the second substrate 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 the fourth configuration example, the explanation of the configuration, operation, and effects, which are the same as those of 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 member not shown that is different from the first substrate 13.

[0129] For example, the electrical connection portion 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 penetrates the through-hole 22a, and the conductive portion 19a is a contact surface that contacts the male thread (not shown). For example, the electrical connection portion 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 penetrates the through-hole 22b, and the conductive portion 19b is a contact surface that contacts the male thread (not shown). For example, the electrical connection portion 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 penetrates the through-hole 22c, and the conductive portion 19c is a contact surface that contacts the male thread (not shown). The electrical connection portions 20a, 20b, and 20c may function as components that realize the above-mentioned 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. The conductive parts 19a and 19b have the largest surface area among the conductive parts 19a, 19b, 19c, and 19d. The surface area of ​​the 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 substrate and the second substrate are electrically connected. In the fifth configuration example, the explanation of the configuration, operation, and effect, which are the same as those of the above-described configuration examples, will be omitted by referring to the above-described explanation. 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. The conductive parts 19a and 19b have the largest surface area among the conductive parts 19a, 19b, 19c, and 19d. The surface area of ​​the 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 substrate. The passive filter 40 may be mounted on the same substrate as the power conversion substrate 106 on which the power conversion circuit 30 (converter 102, DC link 103, and inverter 104) is mounted. In other words, the first substrate 13 on which the passive filter 40 is mounted may be the same as the power conversion substrate 106. A control circuit 105 for controlling the inverter 104 may be mounted on the power conversion circuit 30.

[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.

[0136] This international application claims priority based on Japanese Patent Application No. 2024-169855, filed on 30 September 2024, and the entire contents of Japanese Patent Application No. 2024-169855 are incorporated herein by reference.

[0137] 1 Power Conversion System 10 Power Supply 11 Power Line 12 Ground 13 First Circuit Board 14 Second Circuit Board 15 Fixing Means 16 Connection Terminal 17 Ground Terminal 18 Connection Terminal 19 Conductive Part 20 Electrical Connection Part 21 Load 22a, 22b, 22c Through Hole 23a, 23b, 23c Pin 30 Power Conversion Circuit 40 Passive Filter 41 Common Mode Choke Coil 42 Capacitor 51 Magnetic Material 52 Auxiliary Winding 53, 53r, 53s, 53t Main Winding 55 First Impedance Element 56 Second Impedance Element 60 Generation Unit 60a Output Point 69 Amplification Circuit 70 Output Unit 71 Output Capacitor 72 Output Transformer 81 Drive Power Supply 82 Coupling Capacitor 82a Neutral Point 83, 84 Capacitor 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 device 301, 302 Noise filter

Claims

1. 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.

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

3. The noise filter according to claim 1, wherein the first substrate (13) comprises: a plurality of first capacitors (82) with one terminal connected to each phase of the power line for superimposing the compensation signal onto the power line; a neutral point (82a) to which the other terminals of the plurality of first capacitors are commonly connected; a ground terminal (17) connected to the earth; and a second capacitor (71) with one terminal (71a) connected to the ground terminal for superimposing the compensation signal onto the earth, 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 4, 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 5, wherein the number of layers of the second substrate (14) is greater than the number of layers of the first substrate (13).

7. The noise filter according to any one of claims 1 to 6, wherein the second substrate (14) is provided with a plurality of electrical connection portions (20a, 20b, 20c, 20d) that can be electrically connected to a contacting object, and the electrical connection portion with the largest area of ​​conductive portion that contacts the contacting object electrically connects the first substrate and the second substrate.

8. A power conversion system comprising a noise filter (301) according to any one of claims 1 to 7, and a power conversion circuit (30) for forward conversion or frequency conversion of an AC input through the noise filter.

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

10. A passive filter board electrically connectable to an active noise canceller board (14) on which components for an active noise canceller (180) are mounted, the active noise canceller (180) having a passive filter (40) including a common mode choke coil (41) and a capacitor (43), and outputting a compensation signal to the power line (11) to which the passive filter is connected to reduce common mode noise generated in the power line (11) to which the passive filter is connected, the passive filter board having a plurality of first capacitors (82) to which one terminal is connected to each phase of the power line in order to superimpose the compensation signal on the power line, a neutral point (82a) to which the other terminals of the plurality of first capacitors are commonly connected, and a ground terminal (17) connected to the ground, wherein the neutral point and the ground terminal are electrically connectable to the active noise canceller board, and the active noise canceller board can be fixed to the passive filter board.

11. A passive filter board electrically connectable to an active noise canceller board (14) on which components for an active noise canceller (180) are mounted, the passive filter board comprising a passive filter (40) including a common mode choke coil (41) and a capacitor (43), and which outputs a compensation signal to the power line (11) to which the passive filter is connected, for reducing common mode noise generated in the power line (11) to which the passive filter is connected, comprising: a plurality of first capacitors (82) with one terminal connected to each phase of the power line in order to superimpose the compensation signal onto the power line; a neutral point (82a) to which the other terminals of the plurality of first capacitors are commonly connected; a ground terminal (17) connected to the ground; and a second capacitor (71) with one terminal (71a) connected to the ground terminal in order to superimpose the compensation signal onto the ground, wherein 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. An active noise canceller board comprising an active noise canceller (180) that outputs a compensation signal to the power line (11) or ground (12) to which a passive filter (40) including a common mode choke coil (41) and a capacitor (42) is connected, wherein the active noise canceller board is electrically connectable to a passive filter board (13) on which the passive filter is mounted, and comprises a neutral point (86) of a DC power supply for generating the compensation signal and an output point (60a) of the compensation signal, wherein the neutral point and the output point are electrically connectable to the passive filter board and the active noise canceller board is fixable to the passive filter board.

13. An active noise canceller board comprising an active noise canceller (180) that outputs a compensation signal to the power line (12) or ground (12) to which a passive filter (40) including a common mode choke coil (41) and a capacitor (42) is connected, wherein the active noise canceller board is electrically connectable to a passive filter board (13) on which the passive filter is mounted, and 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) to which one terminal is connected in order to superimpose the compensation signal onto ground, wherein the neutral point and the other terminal of the second capacitor are electrically connectable to the passive filter board, and the active noise canceller board is fixable to the passive filter board.

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