Air conditioning system

Abstract

To reduce common mode noise propagation.SOLUTION: An air conditioning system 1 comprises a first power supply circuit 110, a second power supply circuit 210, first AC power supply lines 11 and 12 that supply power to the first power supply circuit and are connected to ground, second AC power supply lines 21 and 22 that supply power to the second power supply circuit and are connected to ground, a reference potential line 30 that is commonly connected to an output terminal of the first power supply circuit and an output terminal of the second power supply circuit, and an impedance element 151 that is arranged on wiring at a position where a first path from the first AC power supply line to the ground of the second AC power supply line via the coupling capacitance of the transformer of the first power supply circuit and the reference potential line overlaps with a second path from the second AC power supply line to the ground of the first AC power supply line via the coupling capacitance of the transformer of the second power supply circuit and the reference potential line.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to air conditioning systems. [Background technology]

[0002] 2. Description of the Related Art Air conditioners have been proposed that include a power supply circuit that converts the voltage of an external power supply such as a commercial power supply. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-337519 Summary of the Invention [Problem to be solved by the invention]

[0004] An air conditioning system may be constructed by connecting such an air conditioner to an external device equipped with a power supply circuit. In this case, the power supply circuit supplying power to the air conditioner and the power supply circuit supplying power to the external device may be connected to a common reference potential line. In such a system, common-mode noise may propagate to the output side of the power supply circuit via the coupling capacitance of a transformer included in the power supply circuit. Furthermore, common-mode choke coils and Y-capacitor circuits are connected to the input wiring of the air conditioner's power supply circuit and the external device's power supply circuit to reduce the effects of common-mode noise. However, surge voltages may be generated by LC resonance in the common-mode choke coils and Y-capacitors, which may propagate to the output side of the power supply circuit via the coupling capacitance, just like common-mode noise.

[0005] If such noise as common mode noise or surge voltage propagates to the output side of the power supply circuit, it is possible that malfunction will occur in the control unit connected to the power supply circuit, since the output sides of these power supply circuits are connected to a common reference potential line.

[0006] Therefore, the present disclosure proposes a technique for reducing the propagation of common-mode noise. [Means for solving the problem]

[0007] The air conditioning system of the present disclosure includes a first power supply circuit configured by a switching power supply having a transformer and arranged in an indoor unit, a second power supply circuit configured by a switching power supply having a transformer and arranged in an external device, a first AC power supply line that supplies power to the first power supply circuit from an external power supply that outputs AC voltage and is connected to ground, a second AC power supply line that supplies power to the second power supply circuit from the external power supply that outputs AC voltage and is connected to ground, a first rectifier circuit connected to the first AC power supply line and rectifying the AC voltage and outputting it to the first power supply circuit, and a second AC power supply line that rectifies the AC voltage and outputs it to the second AC power supply circuit. the first power supply circuit and the second power supply circuit are connected in common to each other; and an impedance element for reducing common-mode noise current is disposed on wiring at a position where a first path from the first AC power supply line to the ground to which the second AC power supply line is connected via the first rectifier circuit, the coupling capacitance of the transformer of the first power supply circuit, and the reference potential line overlaps with a second path from the second AC power supply line to the ground to which the first AC power supply line is connected via the second rectifier circuit, the coupling capacitance of the transformer of the second power supply circuit, and the reference potential line. [Effects of the Invention]

[0008] According to the air conditioning system of the present disclosure, it is possible to reduce the propagation of common mode noise. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing an example of the configuration of an air conditioning system according to a first embodiment of the present disclosure. [Figure 2] FIG. 2 is a diagram illustrating an example of propagation of common mode noise according to the first embodiment of the present disclosure. [Figure 3] FIG. 3 is a diagram illustrating an example of propagation of common mode noise according to the first embodiment of the present disclosure. [Figure 4] FIG. 4 is a diagram illustrating an example of the configuration of an air conditioning system according to the second embodiment of the present disclosure. [Figure 5] FIG. 5 is a diagram illustrating an example of the configuration of an air conditioning system according to the second embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The description will be given in the following order. In the following embodiments, the same components are designated by the same reference numerals, and redundant description will be omitted. 1. First embodiment 2. Second embodiment

[0011] (1. First embodiment) [Air conditioning system configuration] FIG. 1 is a diagram showing an example configuration of an air conditioning system according to a first embodiment of the present disclosure. FIG. 1 is a circuit diagram showing an example configuration of the air conditioning system 1. The air conditioning system 1 includes an indoor unit 10 and an external device 20. Here, the external device 20 is an optional device such as a refrigerant shut-off valve. The air conditioning system 1 is equipped with a dedicated power supply circuit in advance in preparation for the installation of such a device. The indoor unit 10 and the external device 20 are each connected to an external power supply that outputs AC voltage. The indoor unit 10 is connected to an external power supply 2, and the external device 20 is connected to an external power supply 3. The external power supplies 2 and 3 may be, for example, commercial power supplies.

[0012] The indoor unit 10 includes a common mode choke coil 131, a Y capacitor circuit 132, a first rectifier circuit 120, a first power supply circuit 110, a control circuit 140, and impedance elements 151 and 152.

[0013] The first rectifier circuit 120 rectifies the AC voltage of the external power supply 2 and outputs the rectified voltage to the first power supply circuit 110. The first rectifier circuit 120 in FIG. 1 is configured as a bridge rectifier circuit. The first rectifier circuit 120 is connected to the external power supply 2 via first AC power supply lines 11 and 12. That is, the first AC power supply line 11 is connected to one input terminal of the first rectifier circuit 120, and the first AC power supply line 12 is connected to the other input terminal of the first rectifier circuit 120. The high-potential output terminal of the first rectifier circuit 120 is connected to the wiring 111. The low-potential output terminal of the first rectifier circuit 120 is connected to the reference potential line 30. With this connection, the first AC power supply lines 11 and 12 supply power from the external power supply 2 to the first power supply circuit 110.

[0014] The first AC power supply lines 11 and 12 are connected to the ground by a Y capacitor circuit 132, which will be described later. Of the first AC power supply lines 11 and 12, the wiring from the connection point to the ground to the external power supply 2 side will be referred to as first AC power supply lines 11a and 12a, respectively, and the wiring from the connection point to the ground to the first rectifier circuit 120 side will be referred to as first AC power supply lines 11b and 12b, respectively.

[0015] The first power supply circuit 110 supplies power to the control circuit 140 and the like. The first power supply circuit 110 is configured by a switching power supply having a transformer. The first power supply circuit 110 includes a capacitor 113, a transformer 114, a transistor 115, a diode 116, and a capacitor 117.

[0016] The capacitor 113 is connected between the wiring 111 and the reference potential line 30. One end of the primary winding of the transformer 114 is connected to the wiring 111, and the other end is connected to the collector of the transistor 115. The emitter of the transistor 115 is connected to the reference potential line 30. One end of the secondary winding of the transformer 114 is connected to the anode of the diode 116, and the other end is connected to the reference potential line 30. The cathode of the diode 116 is connected to the wiring 118. The capacitor 117 is connected between the wiring 118 and the reference potential line 30.

[0017] Capacitor 113 smoothes the output voltage of first rectifier circuit 120. Transistor 115 corresponds to a switching transistor and supplies a pulse voltage to the primary winding of transformer 114. Transformer 114 transforms the input voltage to a desired voltage. Diode 116 rectifies the voltage of the secondary winding of transformer 114. Capacitor 117 smoothes the output voltage of diode 116.

[0018] The control circuit 140 controls each part of the indoor unit 10, such as a fan motor and a stepping motor (not shown), etc. This control circuit 140 is configured, for example, by a microcomputer.

[0019] The common mode choke coil 131 is disposed on the first AC power supply lines 11 and 12 (first AC power supply lines 11a and 12a) to reduce common mode noise.

[0020] The Y capacitor circuit 132 is disposed between the first AC power supply line 11 and the first AC power supply line 12 to reduce common mode noise from the external power supply 2. The Y capacitor circuit 132 includes Y capacitors 133 and 134. The Y capacitor 133 is connected between the first AC power supply line 11 and the ground, and the Y capacitor 134 is connected between the first AC power supply line 12 and the ground.

[0021] The common mode choke coil 131 and the Y capacitor circuit 132 constitute a filter circuit 130. The first power supply circuit 110 has a larger output current than the second power supply circuit 210 of the external device 20, which will be described later, and therefore consumes more power. For this reason, the filter circuit 130 is provided to improve noise removal capability.

[0022] The impedance elements 151 and 152 reduce common-mode noise currents. The impedance elements 151 and 152 in Fig. 1 are each formed of a resistor.

[0023] The external device 20 includes a common mode choke coil 231, a Y capacitor circuit 232, a second rectifier circuit 220, a second power supply circuit 210, and a control circuit 240.

[0024] The second rectifier circuit 220 rectifies the AC voltage of the external power supply 3 and outputs the rectified voltage to the second power supply circuit 210. Like the first rectifier circuit 120, the second rectifier circuit 220 is configured as a bridge rectifier circuit. The second rectifier circuit 220 is connected to the external power supply 3 via second AC power supply lines 21 and 22. That is, the first AC power supply line 12 is connected to one input terminal of the second rectifier circuit 220, and the second AC power supply line 22 is connected to the other input terminal of the second rectifier circuit 220. The high-potential side output terminal of the second rectifier circuit 220 is connected to the wiring 211. The low-potential side output terminal of the second rectifier circuit 220 is connected to the reference potential line 30. With this connection, the second AC power supply lines 21 and 22 supply power from the external power supply 3 to the second power supply circuit 210.

[0025] Like the first AC power supply lines 11 and 12, the second AC power supply lines 21 and 22 are connected to the ground by a Y capacitor circuit 232. Of the second AC power supply lines 21 and 22, the wiring from the ground connection point to the external power supply 3 side is referred to as second AC power supply lines 21a and 22a, respectively, and the wiring from the ground connection point to the second rectifier circuit 220 side is referred to as second AC power supply lines 21b and 22b, respectively.

[0026] The second power supply circuit 210 supplies power to the control circuit 240 and the like. Similar to the first power supply circuit 110, the second power supply circuit 210 is configured by a switching power supply having a transformer. The second power supply circuit 210 includes a capacitor 213, a transformer 214, a transistor 215, a diode 216, and a capacitor 217.

[0027] The capacitor 213 is connected between the wiring 211 and the reference potential line 30. One end of a primary winding of a transformer 214 is connected to the wiring 211, and the other end is connected to the collector of a transistor 215. The emitter of the transistor 215 is connected to the reference potential line 30. One end of a secondary winding of the transformer 214 is connected to the anode of a diode 216, and the other end is connected to the reference potential line 30. The cathode of the diode 216 is connected to the wiring 218. The capacitor 217 is connected between the wiring 218 and the reference potential line 30. Note that a description of the functions of the capacitor 213 etc. will be omitted.

[0028] The control circuit 240 controls each part of the external device 20, for example, a cutoff valve drive part when the external device 20 is a refrigerant cutoff valve. The control circuit 240 is configured by, for example, a microcomputer.

[0029] The common mode choke coil 231 is disposed on the second AC power supply lines 21 and 22 (second AC power supply lines 21a and 22a). Note that, since the power consumption of the second power supply circuit 210 is relatively small, the common mode choke coil 231 may be omitted.

[0030] The Y capacitor circuit 232 is disposed between the second AC power supply line 21 and the second AC power supply line 22 to reduce common mode noise from the external power supply 3. The Y capacitor circuit 232 includes Y capacitors 233 and 234. The Y capacitor 233 is connected between the second AC power supply line 21 and the ground, and the Y capacitor 234 is connected between the second AC power supply line 22 and the ground.

[0031] 1, the reference potential line of the primary side circuit of the first power supply circuit 110, the reference potential line of the secondary side circuit of the first power supply circuit 110, the reference potential line of the primary side circuit of the second power supply circuit 210, and the reference potential line of the secondary side circuit of the second power supply circuit 210 are commonly connected to a reference potential line 30. In other words, the reference potential line 30 is commonly connected to the output terminal of the first power supply circuit 110 and the output terminal of the second power supply circuit 210.

[0032] Furthermore, a coupling capacitance exists between the primary winding and the secondary winding of the transformer 114. Similarly, a coupling capacitance exists between the primary winding and the secondary winding of the transformer 214.

[0033] The impedance elements 151 and 152 are arranged at positions where the first path and the second path overlap. Here, the first path represents a path from the first AC power supply lines 11 and 12 to the ground to which the second AC power supply lines 21 and 22 are connected, via the first rectifier circuit 120, the coupling capacitance of the transformer of the first power supply circuit 110, and the reference potential line 30. The second path represents a path from the second AC power supply lines 21 and 22 to the ground to which the first AC power supply lines 11 and 12 are connected, via the second rectifier circuit 220, the coupling capacitance of the transformer 214 of the second power supply circuit 210, and the reference potential line 30.

[0034] The impedance elements 151 and 152 may be disposed at a position where the first path and the second path overlap each other. Therefore, they may be disposed on the side of the second AC power supply lines 21b and 22b, or on the reference potential line 30.

[0035] Of the common mode noise from the external power supply 2, components that could not be removed by the Y capacitor circuit 132 propagate along the first path. Also, of the common mode noise from the external power supply 3, components that could not be removed by the Y capacitor circuit 232 propagate along the second path. Therefore, by placing an impedance element 151 or the like on these paths, it is possible to reduce the common mode noise. This will be explained using Figures 2 and 3.

[0036] [Common mode noise propagation] Fig. 2 is a diagram illustrating an example of propagation of common mode noise according to the first embodiment of the present disclosure. Fig. 2 is a diagram illustrating an example of propagation of common mode noise when impedance elements 151 and 152 are not present. In Fig. 2, AC voltage sources 411 and 412 indicated by dashed lines represent common mode noise voltage. In addition, surge voltages generated by LC resonance of the common mode choke coil 131, the Y capacitor circuit 132, etc. also propagate in a similar manner. Note that in Fig. 2, some of the configurations of the indoor unit 10 and the external device 20 are omitted.

[0037] Common mode noise from the external power supply 2 propagates to ground via a first path that includes the first AC power supply line 11, the first rectifier circuit 120, the wiring 111, the coupling capacitance 401 of the transformer 114, the reference potential line 30, the second rectifier circuit 220, the second AC power supply line 22b, and the Y capacitor 234 (solid arrows in FIG. 2). Furthermore, common mode noise from the external power supply 2 propagates to ground via a first path that includes the first AC power supply line 12, the first rectifier circuit 120, the wiring 111, the coupling capacitance 401 of the transformer 114, the reference potential line 30, the second rectifier circuit 220, the second AC power supply line 21b, and the Y capacitor 233 (dotted arrows in FIG. 2).

[0038] Common mode noise from the external power supply 3 propagates to ground via a second path that includes the second AC power supply line 21, the second rectifier circuit 220, the wiring 211, the coupling capacitance 402 of the transformer 214, the reference potential line 30, the first rectifier circuit 120, the first AC power supply line 12b, and the Y capacitor 134 (indicated by the dashed-dotted arrow in FIG. 2). Furthermore, common mode noise from the external power supply 3 propagates to ground via a second path that includes the second AC power supply line 22, the second rectifier circuit 220, the wiring 211, the coupling capacitance 402 of the transformer 214, the reference potential line 30, the first rectifier circuit 120, the first AC power supply line 11b, and the Y capacitor 133 (indicated by the dashed-dotted arrow in FIG. 2).

[0039] In this way, the current due to the common mode noise applied to the first AC power supply lines 11 and 12 flows along the first path, while the current due to the common mode noise applied to the second AC power supply lines 21 and 22 flows along the second path.

[0040] FIG. 3 is a diagram illustrating an example of common-mode noise propagation according to the first embodiment of the present disclosure. FIG. 3 illustrates an example of common-mode noise propagation when impedance elements 151 and 152 are present. By arranging impedance element 151 or the like at the position where the first and second paths overlap, the impedance of the wiring included in the first and second paths can be increased. As a result, common-mode noise current from external power source 2 does not flow through the first path but flows to ground via Y capacitor circuit 132. Furthermore, common-mode noise current from external power source 3 does not flow through the second path but flows to ground via Y capacitor circuit 232. Therefore, when external device 20 is connected to indoor unit 10, the propagation of both noise from indoor unit 10 and external device 20 can be simultaneously suppressed, preventing malfunction of control circuit 140 and control circuit 240. Note that surge voltage generated by the LC resonance described above also propagates in the same way as common-mode noise, and this propagation can also be suppressed.

[0041] Furthermore, it is preferable to place an impedance element 151 or the like on either the first AC power supply lines 11b and 12b or the second AC power supply lines 21b and 22b among the positions where the first path and the second path overlap. The position where the first path and the second path overlap includes the reference potential line 30. However, because a DC current flows through this reference potential line 30, if an impedance element 151 such as a resistor is placed on the reference potential line 30, a potential difference occurs when a load current flows through the reference potential line 30, causing the potential of the reference potential line 30 to fluctuate. This causes the voltage of the reference potential line 30, which should be 0 V, to fluctuate, which may lead to malfunction of the control circuit 140. By placing the impedance element 151 or the like in a portion other than the reference potential line 30, malfunctions can be prevented.

[0042] Furthermore, it is more preferable to place the impedance elements 151 and the like on the wiring between the filter circuit 130 and the first rectifier circuit 120 of the first AC power supply lines 11 and 12. A larger current flows through the first power supply circuit 110, which is the power supply for the indoor unit 10, than through the second power supply circuit 210, which is the power supply for the external device 20. Therefore, the common-mode noise current propagating through the first path is larger than the common-mode noise current propagating through the second path. If the impedance elements 151 and the like are placed at a location other than between the filter circuit 130 and the first rectifier circuit 120 of the first AC power supply lines 11 and 12, the common-mode noise current may flow to the ground not only via the Y capacitor circuit 132 but also via stray capacitance between the wiring and the housing sheet metal along the first path leading to the location where the impedance elements 151 and the like are placed. Therefore, placing the impedance elements 151 and the like at the above-described locations can further suppress the propagation of common-mode noise.

[0043] Furthermore, at the frequency of noise propagating through the first path, the impedance of the first path including impedance elements 151 and 152 is greater than the impedance of Y capacitors 133 and 134 included in Y capacitor circuit 132. Furthermore, at the frequency of noise propagating through the second path, the impedance of the second path including impedance elements 151 and 152 is greater than the impedance of Y capacitors 233 and 234 included in Y capacitor circuit 232. As a result, Y capacitors 133 and the like have lower impedance than impedance elements 151 and the like, and common mode noise propagating through the first path and the second path can be reduced.

[0044] (2. Second Embodiment) Variations of the air conditioning system 1 will be described.

[0045] Figures 4 and 5 are diagrams showing a configuration example of an air conditioning system according to a second embodiment of the present disclosure. Figures 4 and 5 are diagrams showing a configuration example of an air conditioning system 1. Note that Figures 4 and 5 are simplified versions of the air conditioning system 1.

[0046] 4 shows an example in which impedance element 152 is omitted and only impedance element 151 is arranged. Impedance element 151 can also be arranged on the side of first AC power supply line 12b. Impedance element 151 can also be arranged on either second AC power supply line 21b or 22b. In such an embodiment, the impedance of part of the wiring included in the first path and the second path can be increased, thereby reducing common-mode noise propagating through the first path and the second path.

[0047] FIG. 5 shows an example in which an impedance element 153 is arranged on the reference potential line 30. In FIG.

[0048] It is also possible to use an inductor such as a coil instead of a resistor as the impedance element 151, etc. However, when an inductor is used, the effect on emission noise is greater than when a resistor is used, and it may be necessary to change the constants of, for example, the common mode choke coil 131 or the Y capacitor circuit 132. Therefore, it is more desirable to use a resistor as the impedance 151, etc.

[0049] [Effects of the Example] The air conditioning system includes a first power supply circuit configured by a switching power supply having a transformer and disposed in an indoor unit, a second power supply circuit configured by a switching power supply having a transformer and disposed in an external device, a first AC power supply line that supplies power to the first power supply circuit from an external power supply that outputs AC voltage and is connected to ground, a second AC power supply line that supplies power to the second power supply circuit from the external power supply that outputs AC voltage and is connected to ground, a first rectifier circuit connected to the first AC power supply line and rectifying the AC voltage and outputting it to the first power supply circuit, and a second AC power supply line that is connected to the second AC power supply line and rectifying the AC voltage and outputting it to the second power supply circuit. a reference potential line commonly connected to an output terminal of the first power supply circuit and an output terminal of the second power supply circuit, and an impedance element disposed on wiring at a position where a first path extending from the first AC power supply line via the first rectifier circuit, a coupling capacitance of a transformer of the first power supply circuit, and the reference potential line to a ground to which the second AC power supply line is connected overlaps with a second path extending from the second AC power supply line via the second rectifier circuit, the coupling capacitance of a transformer of the second power supply circuit, and the reference potential line to a ground to which the first AC power supply line is connected, thereby making it possible to reduce common-mode noise currents propagating along the first and second paths.

[0050] The impedance element may be disposed on either a wiring from the ground connection point of the first AC power supply line to the first rectifier circuit or a wiring from the ground connection point of the second AC power supply line to the second rectifier circuit, thereby preventing voltage fluctuations on the reference potential line.

[0051] The power supply may further include a filter circuit including a choke coil and a Y capacitor circuit arranged on the first AC power line, the first AC power line being connected to the ground via the Y capacitor circuit, and the impedance element being arranged on a wiring between the filter circuit and the first rectifier circuit on the first AC power line. This makes it possible to reduce common-mode noise current passing through the first power supply circuit, through which a relatively large current flows.

[0052] The power supply circuit may further include a first Y capacitor circuit connected to the first AC power line and a second Y capacitor circuit connected to the second AC power line, wherein the first AC power line is connected to the ground via the first Y capacitor circuit, the second AC power line is connected to the ground via the second Y capacitor circuit, and the impedance of the impedance element at the frequency of noise propagating through the first path is greater than the impedance of a Y capacitor included in the first Y capacitor circuit, and the impedance of the impedance element at the frequency of noise propagating through the second path is greater than the impedance of a Y capacitor included in the second Y capacitor circuit, thereby reducing common-mode noise current flowing through the first path and the second path.

[0053] The impedance element may be a resistor, which makes it possible to reduce common-mode noise currents in a simple manner.

[0054] The effects described in this specification are merely examples and are not limiting, and other effects may also be present. [Explanation of symbols]

[0055] 1. Air conditioning system 2, 3 External power supply 10 Indoor unit 11, 11a, 11b, 12, 12a, 12b First AC power supply line 20 External equipment 21, 21a, 21b, 22, 22a, 22b Second AC power supply lines 30 Reference potential line 110 first power supply circuit 114, 214 transformer 120 First rectifier circuit 130 Filter Circuit 131, 231 Common mode choke coil 132, 232 Y capacitor circuit 133, 134, 233, 234 Y capacitors 151-153 Impedance elements 210 second power supply circuit 220 Second rectifier circuit

Claims

1. a first power supply circuit configured with a switching power supply having a transformer and disposed in the indoor unit; a second power supply circuit configured by a switching power supply having a transformer and disposed in the external device; a first AC power supply line that supplies power to the first power supply circuit from an external power supply that outputs an AC voltage and is connected to ground; a second AC power supply line that supplies power to the second power supply circuit from an external power supply that outputs an AC voltage and is connected to ground; a first rectifier circuit connected to the first AC power supply line to rectify the AC voltage and output the rectified AC voltage to the first power supply circuit; a second rectifier circuit connected to the second AC power supply line to rectify the AC voltage and output the rectified AC voltage to the second power supply circuit; a reference potential line commonly connected to an output terminal of the first power supply circuit and an output terminal of the second power supply circuit; an impedance element for reducing common-mode noise current, the impedance element being disposed on wiring at a position where a first path extending from the first AC power supply line via the first rectifier circuit, the coupling capacitance of the transformer of the first power supply circuit, and the reference potential line to the ground to which the second AC power supply line is connected, and a second path extending from the second AC power supply line via the second rectifier circuit, the coupling capacitance of the transformer of the second power supply circuit, and the reference potential line to the ground to which the first AC power supply line is connected, overlap; An air conditioning system comprising:

2. 2. The air conditioning system according to claim 1, wherein the impedance element is arranged in either a wiring from the ground connection point of the first AC power supply line to the first rectifier circuit or a wiring from the ground connection point of the second AC power supply line to the second rectifier circuit.

3. further comprising a filter circuit including a choke coil and a Y capacitor circuit disposed on the first AC power supply line; the first AC power supply line is connected to the ground via the Y capacitor circuit; The impedance element is disposed on a wiring between the filter circuit and the first rectifier circuit of the first AC power supply line.

3. The air conditioning system according to claim 1 or 2.

4. a first Y capacitor circuit connected to the first AC power supply line; a second Y capacitor circuit connected to the second AC power supply line; Further comprising: the first AC power supply line is connected to the ground via the first Y capacitor circuit; the second AC power supply line is connected to the ground via the second Y capacitor circuit; The impedance element has an impedance at a frequency of the noise propagating through the first path that is greater than the impedance of a Y capacitor included in the first Y capacitor circuit, and an impedance at a frequency of the noise propagating through the second path that is greater than the impedance of a Y capacitor included in the second Y capacitor circuit. The air conditioning system of claim 1 .

5. The air conditioning system according to claim 1 , wherein the impedance element is a resistor.

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