Power conversion system and air conditioner

Abstract

To provide a technology capable of suppressing the current capacity required for disconnection means that interrupts power supply from a drive power source to an active noise suppression circuit.SOLUTION: A power conversion system 1 includes a power conversion circuit 30C, a noise suppression circuit 60C that outputs a compensation current to a propagation path to suppress common-mode noise, a drive power supply 70, and a disconnector 67. The noise suppression circuit 60C includes an amplifier circuit 62 that is supplied with power from the drive power supply 70 and generates a signal representing the waveform of the compensation current on the basis of a detection signal from noise detection means 50, and a compensation circuit 63 that is powered by the drive power supply 70 in parallel with the amplifier circuit 62, and outputs a compensation current on the basis of the signal generated by the amplifier circuit 62. The circuit breaker 67 is arranged in a power path 71 that supplies power from the drive power supply 70 only to the amplifier circuit 62 of the amplifier circuit 62 and the compensation circuit 63, and interrupts the power supply to the amplifier circuit 62.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a power conversion system and the like. [Background technology]

[0002] Conventionally, a technique is known in which a cutoff means for cutting off the power supply between an active noise suppression circuit and a drive power supply is provided, and in the event of an abnormality in the noise suppression circuit, the power supply from the drive power supply to the noise suppression circuit is cut off (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2023 / 105687 Summary of the Invention [Problem to be solved by the invention]

[0004] In a noise suppression device, a surge current due to a lightning strike may flow in the compensation voltage or in the path through which a current flows when the compensation voltage is output. In this case, the surge current due to a lightning strike may flow into the interrupter between the drive power supply and the noise suppression circuit. Therefore, it may be necessary to increase the current capacity of the interrupter to a level that can withstand the surge current.

[0005] An object of the present disclosure is to provide a technique that can reduce the current capacity required for a cutoff means that cuts off the power supply from a drive power supply to an active noise suppression circuit. [Means for solving the problem]

[0006] In a first aspect of the present disclosure, a power conversion circuit connected to the AC power supply through a power line; a noise suppression circuit that outputs a compensation current or a compensation voltage to the propagation path including the power line so as to suppress common mode noise flowing in the propagation path; a driving power supply that supplies power for driving the noise suppression circuit; a blocking means, the noise suppression circuit includes a first circuit that receives power from the drive power supply, and a second circuit that receives power from the drive power supply in parallel with the first circuit, and receives a current that is larger than that of the first circuit when the compensation current or the compensation voltage is output to the propagation path, the cutoff means is disposed in a power path that supplies power from the drive power supply to only the first circuit of the first circuit and the second circuit, and cuts off the supply of power to the first circuit. A power conversion system is provided.

[0007] In addition, in a second aspect of the present disclosure, a power conversion circuit connected to the AC power supply through a power line; a noise suppression circuit that outputs a compensation current or a compensation voltage to the propagation path including the power line so as to suppress common mode noise flowing in the propagation path; a driving power supply that supplies power for driving the noise suppression circuit; a blocking means, the noise suppression circuit includes: a first circuit that receives power from the drive power supply and generates a signal representing a waveform of the compensation current or the compensation voltage based on a detection signal from a detection means that detects the common mode noise; and a second circuit that receives power from the drive power supply in parallel with the first circuit and outputs the compensation current or the compensation voltage based on the signal generated by the first circuit, the cutoff means is disposed in a power path that supplies power from the drive power supply to only the first circuit of the first circuit and the second circuit, and cuts off the supply of power to the first circuit. A power conversion system is provided.

[0008] According to the first or second aspect, under the assumption that power from the driving power supply is supplied in parallel to the first circuit and the second circuit, the interrupting means is provided only in the power path that supplies power to the first circuit, not in the second circuit through which current flows when a compensation current or a compensation voltage is output. Therefore, in the power conversion system, for example, a surge current due to a lightning strike is likely to flow in the second circuit through which current flows when a compensation current or a compensation voltage is output, so that the surge current due to a lightning strike is less likely to flow in the interrupting means. Therefore, the power conversion system can reduce the current capacity required for the interrupting means that interrupts the power supply from the driving power supply to the active noise suppression circuit.

[0009] In addition, in a third aspect of the present disclosure, based on the first or second aspect described above, The first circuit may include an operational amplifier.

[0010] In addition, in a fourth aspect of the present disclosure, on the premise of any one of the first to third aspects described above, The second circuit may include a push-pull circuit including a transistor.

[0011] In addition, in a fifth aspect of the present disclosure, on the premise of any one of the first to fourth aspects described above, A noise filter may be provided on the power line between a point where the noise suppression circuit is connected and the power conversion circuit.

[0012] In addition, in a sixth aspect of the present disclosure, on the premise of any one of the first to fifth aspects described above, the power conversion circuit includes a switching element; The switching element may be made of a wide bandgap semiconductor.

[0013] In addition, a seventh aspect of the present disclosure is a power conversion system including any one of the first to sixth aspects described above. An air conditioner is provided. [Effects of the Invention]

[0014] According to the above-described embodiment, it is possible to reduce the current capacity required for the cutoff means that cuts off the power supply from the drive power supply to the active noise suppression circuit. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a diagram illustrating an example of a power conversion system. [Figure 2] FIG. 1 is a diagram illustrating a power conversion system according to a comparative example. [Figure 3] FIG. 1 is a diagram illustrating an example of a refrigerant circuit of an air conditioner. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, an embodiment will be described with reference to the drawings.

[0017] [Power conversion system configuration] The configuration of a power conversion system 1 according to this embodiment will be described with reference to FIG.

[0018] FIG. 1 is a diagram illustrating an example of a power conversion system 1. As shown in FIG.

[0019] As shown in FIG. 1, a power conversion system 1 drives a motor 20 using power supplied from an AC power supply 10.

[0020] The AC power supply 10 supplies AC current to the power conversion system 1. In this example, the AC power supply 10 supplies three-phase AC current, that is, R-phase, S-phase, and T-phase, to the power conversion system 1.

[0021] The motor 20 is driven by a three-phase AC current output from the power conversion system 1. The motor 20 is, for example, a DC (Direct Current) brushless motor. The motor 20 may also be a motor driven by another three-phase AC current.

[0022] The power conversion system 1 includes a power line PL1, a power line PL2, a power conversion device 30, a noise filter 40, a noise detection means 50, an active noise canceller 60, and a drive power supply .

[0023] Power line PL1 is made up of three power lines of R phase, S phase, and T phase, and electrically connects AC power supply 10 and power conversion device 30. Power line PL1 includes power lines PL11 to PL13.

[0024] The power line PL2 electrically connects the power converter 30 and the motor 20 by three power lines of U-phase, V-phase, and W-phase.

[0025] Power line PL11 connects AC power supply 10 and coil 51 via three power lines of R phase, S phase, and T phase. Power line PL12 connects coil 51 and common mode choke coil 41 of noise filter 40 via three power lines of R phase, S phase, and T phase. Power line PL13 connects common mode choke coil 41 and power conversion device 30 via three power lines of R phase, S phase, and T phase.

[0026] The power conversion device 30 converts the AC supplied through the power line PL1 into three-phase AC of a predetermined frequency and a predetermined voltage, and outputs the converted AC to the motor 20 through the power line PL2, thereby driving the motor 20.

[0027] The power conversion device 30 includes a power conversion circuit 30C including a rectifier circuit 31 and an inverter circuit 32, and a control circuit 33, for example.

[0028] The rectifier circuit 31 converts three-phase AC of R phase, S phase, and T phase supplied through the power line PL13 into DC and outputs it to the DC link. The rectifier circuit 31 is, for example, a three-phase full-wave rectifier circuit using diodes.

[0029] The inverter circuit 32 converts the DC input from the DC link between the rectifier circuit 31 and itself into three-phase AC of a predetermined frequency and a predetermined voltage, specifically AC of U phase, V phase, and W phase, and outputs the converted AC. The inverter circuit 32 includes, for example, switching elements, and converts the DC into three-phase AC of a predetermined frequency and a predetermined voltage through the switching operation of the switching elements, and outputs the converted AC to the power line PL2.

[0030] The switching elements are, for example, IGBTs (Insulated Gate Bipolar Transistors), MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors), HEMTs (High Electron Mobility Transistors), etc. The switching elements are, for example, mainly made of silicon (Si). The switching elements may also be mainly made of a wide bandgap semiconductor material. Examples of wide bandgap semiconductor materials include silicon carbide (SiC), gallium nitride (GaN), gallium oxide (Ga2O3), and carbon (diamond: C). The inverter circuit 32 may also include, in addition to the switching elements, semiconductor freewheel diodes connected in parallel with the switching elements.

[0031] The control circuit 33 performs control processing related to the power conversion circuit 30C.

[0032] The control circuit 33 may also perform other processes related to the power conversion system 1.

[0033] For example, the control circuit 33 performs processing for diagnosing an abnormality in the active noise canceller 60 (hereinafter referred to as "abnormality diagnosis"). The abnormality diagnosis includes, for example, diagnosing the presence or absence of an abnormality. The abnormality diagnosis may also include diagnosing the presence or absence of signs of an abnormality and diagnosing the degree of the abnormality (degree of abnormality).

[0034] The functions of the control circuit 33 may be realized by only the hardware (circuit) of the hardware and software, or may be realized by a combination of hardware (for example, an integrated circuit (IC)) and software. In the latter case, for example, the control circuit 33 is mainly configured with a microcomputer including a CPU (Central Processing Unit), a memory device, an auxiliary storage device, an input / output interface, etc.

[0035] The noise filter 40 is a passive noise suppression device that suppresses common mode noise.

[0036] Common mode noise occurs in association with the switching operation of the switching elements of the inverter circuit 32. Specifically, common mode noise occurs when noise caused by the switching operation of the switching elements leaks to the ground GL through the stray capacitance of the motor 20 or the stray capacitance between the switching elements (not shown) of the power conversion device 30 and the heat sink.

[0037] The noise filter 40 includes a common mode choke coil 41 and a Y capacitor 42 .

[0038] The common mode choke coil 41 acts as an inductor to suppress a common mode noise current (common mode current) flowing through the power line PL1.

[0039] The Y capacitor 42 has a function of returning the common mode current that has flowed out to the ground GL to the inverter circuit 32, which is a noise source. One end of the Y capacitor 42 is connected to the power line PL13, and the other end is connected to the ground GL.

[0040] The ground GL is earthed, and is, for example, the housing of a device including the power conversion system 1. Alternatively, the ground GL may be a dedicated reference potential line.

[0041] The noise detection means 50 detects a common mode noise current (common mode current) or a noise voltage (common mode voltage). For example, as shown in FIG. 1, the noise detection means 50 detects a common mode current in the power line PL1. The noise detection means 50 includes a coil 51 and a coil 52.

[0042] The coils 51 are provided for the R-phase, S-phase, and T-phase of the power line PL1, respectively.

[0043] Coil 52 is provided so as to be magnetically coupled to coil 51. Coil 52 outputs a detection signal corresponding to the common mode noise on power line PL1.

[0044] Coils 51 and 52 are wound around the same magnetic core and are arranged to have opposite polarities, as indicated by the "·" in FIG. 1. The magnetic core around which coils 51 and 52 are wound is, for example, a toroidal core, and the magnetic material is, for example, ferrite or permium. For example, when current flows to the right in coil 51 in the figure, current flows to the left in coil 52. In other words, the polarity indicated by the "·" in FIG. 1 corresponds to the direction in which current flows.

[0045] For example, when a common mode current flows through coil 51, a current proportional to the common mode current is induced in coil 52. As a result, coils 51 and 52 function as a current detection transformer that detects the common mode current. Furthermore, noise detection unit 50 may detect common mode noise in ground GL.

[0046] The active noise canceller 60 outputs a compensation current or a compensation voltage for suppressing common mode noise to the power line PL1, the power line PL2, or the ground GL based on the detection signal output from the coil 52 of the noise detection means 50. The active noise canceller 60 includes a noise suppression circuit 60C including a filter circuit 61, an amplifier circuit 62, a compensation circuit 63, an output unit 64, a power supply circuit 65, a coupling capacitor 66, and a circuit breaker 67, and a control circuit 68.

[0047] The filter circuit 61 passes a signal obtained by removing a specific frequency component from the detection signal output from the coil 52 , and the output signal of the filter circuit 61 is input to the amplifier circuit 62 .

[0048] The amplifier circuit 62 amplifies the signal output from the filter circuit 61. The amplifier circuit 62 includes an operational amplifier 621, for example.

[0049] The power supply voltage of the operational amplifier 621 is, for example, 2 / 3 or less of the voltage (DC link voltage) Vdc of the DC link (also referred to as the "direct current link") of the power conversion circuit 30C. Because the voltage Vcom of the common-mode noise source (specifically, the potential of the neutral point of the motor 20 generated when the motor 20 is driven by the inverter circuit 32) changes by 1 / 3, if the power supply voltage of the operational amplifier 621 is within a range of ±1 / 3 of the DC link voltage Vdc, it is possible to cancel out the common-mode noise caused by the switching operation of the inverter circuit 32 without considering the relationship between the voltage Vcc and the impedance.

[0050] The signal output from the amplifier circuit 62 is a signal representing the waveform of a compensation current or a compensation voltage, and is input to the compensation circuit 63. The signal representing the waveform of a compensation current or a compensation voltage is a signal indicating the amplitude and phase for each frequency of the waveform of the compensation current or the compensation voltage output from the compensation circuit 63. For example, the signal representing the waveform of the compensation current or the compensation voltage output from the amplifier circuit 62 is a current or voltage waveform signal that has the same phase for each frequency as the waveform of the compensation current or the compensation current output from the compensation circuit 63, but has a smaller amplitude.

[0051] The compensation circuit 63 amplifies the signal output from the amplifier circuit 62 and outputs a compensation current or a compensation voltage. The compensation circuit 63 includes transistors Tr1 and Tr2 and diodes D1 and D2.

[0052] The transistor Tr1 is connected between one end of the drive power supply 70 and the output capacitor Co of the output section 64. The transistor Tr2 is connected between the other end of the drive power supply 70 and the output capacitor Co of the output section 64.

[0053] 1, in this example, the transistor Tr1 is a PNP type, the transistor Tr2 is an NPN type, and the transistors Tr1 and Tr2 have opposite polarities, so that the transistors Tr1 and Tr2 form a push-pull circuit, which functions as an amplifier.

[0054] The bases of the transistors Tr1 and Tr2 are connected to one end of the coil 52 via the amplifier circuit 62 and the filter circuit 61, and the interconnection point of the transistors Tr1 and Tr2 is connected to the other end of the coil 52 via the amplifier circuit 62 and the filter circuit 61. This causes the transistors Tr1 and Tr2 to operate in opposite directions.

[0055] Diodes D1 and D2 are connected in antiparallel to the transistors Tr1 and Tr2, respectively, to protect them.

[0056] The output unit 64 connects the compensation circuit 63 and the ground GL, and outputs (also referred to as "injecting") the compensation current or compensation voltage output from the compensation circuit 63 to a path through which the common mode current flows. The output unit 64 includes an output capacitor Co.

[0057] One end of the output capacitor Co is connected to the interconnection point of the transistors Tr1 and Tr2 of the compensation circuit 63, and the other end is connected to the ground GL.

[0058] The power supply circuit 65 is connected to a drive power supply 70. The power supply circuit 65 includes capacitors C1 and C2.

[0059] The capacitors C1 and C2 are connected in series. The series connection of the capacitors C1 and C2 is connected in parallel with the driving power supply 70 and the compensation circuit 63. The midpoint between the capacitors C1 and C2 is connected to the coupling capacitor 66.

[0060] Coupling capacitor 66 has one end connected to power line PL12 and the other end connected to the midpoint between capacitors C1 and C2.

[0061] The circuit breaker 67 is provided on the power path 71 of the power paths 71 and 72 that supply power in parallel from the driving power source 70 to the amplifier circuit 62 and the compensation circuit 63. The circuit breaker 67 can switch between a connection state in which power can be supplied from the driving power source 70 to the amplifier circuit 62 via the power path 71, and a cut-off state in which the power supply from the driving power source 70 to the amplifier circuit 62 via the power path 71 is cut off. The circuit breaker 67 is, for example, a relay. Alternatively, the circuit breaker 67 may be a semiconductor switch.

[0062] For example, when an abnormality diagnosis of the active noise canceller 60 determines that the active noise canceller 60 has an abnormality, the circuit breaker 67 cuts off the power supply to the amplifier circuit 62 through the power path 71. This makes it possible to stop the operation of the amplifier circuit 62, for example, when an abnormality occurs in the active noise canceller 60 and the active noise canceller 60 is unable to output an appropriate compensation current or compensation voltage. As a result, the compensation circuit 63 downstream of the amplifier circuit 62 is unable to output a compensation current or compensation current, and the circuit breaker 67 can stop the operation of the noise suppression circuit 60C of the active noise canceller 60. Therefore, the power conversion system 1 can prevent a situation in which, for example, an abnormal compensation current or compensation voltage not only makes it impossible to suppress common-mode noise but also causes problems such as the common-mode noise going into an oscillation state.

[0063] The circuit breaker 67 switches between a connected state and a disconnected state in response to a control command from the control circuit 68, for example. In this case, for example, when the control circuit 68 obtains a result of an abnormality diagnosis indicating that an abnormality exists in the active noise canceller 60, it sends a control command to the circuit breaker 67 to switch the circuit breaker 67 from the connected state to the disconnected state. The circuit breaker 67 may also be manually switched between the connected state and the disconnected state by a person such as a user or an operator. In this case, for example, the user or operator who has received a notification of the result of the abnormality diagnosis of the active noise canceller 60 manually switches the circuit breaker 67 from the connected state to the disconnected state.

[0064] The control circuit 68 performs control processing related to the active noise canceller 60 .

[0065] The control circuit 68 may also perform processing for diagnosing abnormalities in the active noise canceller 60.

[0066] The functions of the control circuit 68 may be realized by only the hardware (circuit) of the hardware and software, or may be realized by a combination of hardware (for example, an integrated circuit) and software, etc. In the latter case, for example, the control circuit 68 is mainly configured with a microcomputer including a CPU, a memory device, an auxiliary storage device, an input / output interface, etc.

[0067] The drive power supply 70 supplies DC drive power to the active noise canceller 60. In this example, the drive power supply 70 supplies power in parallel to the amplifier circuit 62 and the compensation circuit 63, as described above.

[0068] Specifically, the driving power supply 70 supplies power to the amplifier circuit 62 through a power path 71 that can supply power only to the amplifier circuit 62 out of the amplifier circuit 62 and the compensation circuit 63, and supplies power to the compensation circuit 63 through a power path 72 that can supply power only to the compensation circuit 63. The power paths 71 and 72 that supply power from the driving power supply 70 branch off from a power path 73 that is connected to the driving power supply 70.

[0069] [Active noise canceller operation] Next, the operation of the active noise canceller will be described with reference to FIG.

[0070] In the following, for simplicity, the present example will be described ignoring the effect of the noise filter 40 in suppressing the common mode current Ic.

[0071] The noise detection means 50 detects common mode noise on the power line PL1 and drives the transistors Tr1 and Tr2 via a filter circuit 61 and an amplifier circuit 62. Specifically, when a detection signal output from the coil 52 of the noise detection means 50 is input to the bases of the transistors Tr1 and Tr2 via the filter circuit 61 and the amplifier circuit 62, the detection signal is amplified by the transistors Tr1 and Tr2.

[0072] 1, the transistor Tr1 is turned on. In this case, the compensation current Io is supplied from the drive power supply 70 and flows through a path that connects the positive terminal of the drive power supply 70 to the negative terminal of the drive power supply 70 via the capacitor C2, the coupling capacitor 66, the AC power supply 10, the output capacitor Co, and the transistor Tr1. As a result, the compensation current Io is subtracted from the common mode current Ic, and a reduced common mode current Ig flows through the AC power supply 10.

[0073] Furthermore, when the common mode current Ic flows in the direction opposite to the direction of the arrow in Fig. 1, the transistor Tr2 is turned on. In this case, the compensation current Io is supplied from the drive power supply 70 and flows through a current path that connects the positive terminal of the drive power supply to the negative terminal of the drive power supply 70, via the transistor Tr2, the output capacitor Co, the AC power supply 10, the coupling capacitor 66, and the capacitor C1. In other words, the compensation current Io flows in the direction opposite to the direction of the arrow in Fig. 1. As a result, the compensation current Io is subtracted from the common mode current Ic, and a reduced common mode current Ig flows in the direction opposite to the direction of the arrow in Fig. 1 to the AC power supply 10.

[0074] As described above, the compensation current Io flows through the compensation circuit 63. Therefore, the current supplied from the driving power supply 70 when the compensation current or compensation voltage is output is larger in the compensation circuit 63 than in the amplifier circuit 62.

[0075] In this way, the active noise canceller 60 outputs the compensation current Io to the path through which the common mode current Ic flows, thereby suppressing the common mode current Ig flowing through the AC power supply 10. Therefore, for example, the active noise canceller 60 can prevent a situation in which a common mode noise current flows out to a peripheral device through the AC power supply 10 and affects the device.

[0076] [Active noise canceller abnormality diagnosis] Next, abnormality diagnosis of the active noise canceller 60 will be described.

[0077] In this example, the control circuit 68 of the active noise canceller 60 and the control circuit 33 of the power conversion device 30 perform processing related to abnormality diagnosis of the active noise canceller 60. For example, the processing related to abnormality diagnosis of the active noise canceller 60 is composed of the following steps (1) to (8).

[0078] (1) Detection of diagnostic physical quantities The control circuit 68 acquires at least one of the detection signal output from the coil 52 of the noise detection means 50 and a signal derived from the detection signal, and detects a physical quantity for diagnosis.

[0079] The signal derived from the detection signal output from the coil 52 includes, for example, a signal output from the filter circuit 61, a signal output from the amplifier circuit 62, a signal representing a compensation current or a compensation voltage output from the compensation circuit 63, and a signal representing a compensation current or a compensation voltage output from the output unit 64. The signal representing a compensation current or a compensation voltage does not include the compensation current or the compensation voltage itself, but includes, for example, a signal obtained by converting the compensation current or the compensation voltage into a voltage equivalent to a weak current. If there are multiple types of signals derived from the detection signal output from the coil 52, signals derived from two or more types of detection signals may be acquired. Hereinafter, for convenience, the type of signal acquired in step (1) may be referred to as the "signal to be diagnosed."

[0080] The diagnostic physical quantity is a physical quantity represented by a signal to be diagnosed, such as a current or a voltage.

[0081] When the processing of step (1) is completed, the control circuit 68 proceeds to step (2).

[0082] (2) Judgment of success or failure of diagnostic conditions related to diagnostic physics The control circuit 68 determines whether the diagnostic conditions related to the physical quantities for diagnosis detected in step (1) are met.

[0083] The diagnostic conditions represent conditions related to abnormality diagnosis of the active noise canceller 60. For example, the diagnostic conditions related to the physical quantity for diagnosis are specified for each type of signal to be diagnosed acquired in step (1), and are conditions that represent whether the magnitude of the physical quantity for diagnosis is equal to or exceeds a threshold value. This is because, if the magnitude of the current, voltage, etc. corresponding to the detection signal output from the coil 52 is relatively large, common mode noise is not being appropriately suppressed, and the active noise canceller 60 is likely to have an abnormality.

[0084] When the processing of step (2) is completed, the control circuit 68 proceeds to step (3).

[0085] (3) Abnormality diagnosis The control circuit 68 performs an abnormality diagnosis of the active noise canceller 60 based on the result of the determination of whether the diagnostic conditions relating to the physical quantities for diagnosis are met in step (2).

[0086] For example, the control circuit 68 performs an abnormality diagnosis based on whether a diagnostic condition related to a diagnostic physical quantity is satisfied at a certain point in time. Furthermore, the control circuit 68 may perform an abnormality diagnosis of the active noise canceller 60 by taking into consideration additional diagnostic conditions, such as the number of times the diagnostic condition related to the diagnostic physical quantity is satisfied and the cumulative time over which the diagnostic condition is satisfied, in addition to whether the diagnostic condition related to the diagnostic physical quantity is satisfied at a certain time in the diagnostic mode. For example, the control circuit 68 performs an abnormality diagnosis of the active noise canceller 60 based on whether the cumulative time or the number of times the diagnostic condition related to the diagnostic physical quantity is satisfied over a certain period in the diagnostic mode exceeds a predetermined threshold.

[0087] When the processing of step (3) is completed, the control circuit 68 proceeds to step (4), for example, if the result of the abnormality diagnosis indicates that there is an abnormality in the active noise canceller 60, or proceeds to step (5) if the result of the abnormality diagnosis indicates that there is no abnormality in the active noise canceller 60. Furthermore, the control circuit 68 may proceed to step (4) if the result of the abnormality diagnosis indicates that the degree of abnormality (degree of abnormality) of the active noise canceller 60 is equal to or greater than a predetermined standard, or proceed to step (5) if the degree of abnormality of the active noise canceller 60 is less than the predetermined standard.

[0088] (4) Active noise canceller is disabled When the control circuit 68 diagnoses that there is an abnormality in the active noise canceller 60 as a result of the abnormality diagnosis in step (3), it outputs a control command to the circuit breaker 67 to switch the circuit breaker 67 from the connected state to the disconnected state. When the control circuit 68 diagnoses that the degree of abnormality (degree of abnormality) in the active noise canceller 60 is equal to or exceeds a predetermined standard as a result of the abnormality diagnosis in step (3), it may output a control command to the circuit breaker 67 to switch the circuit breaker 67 from the connected state to the disconnected state. In this way, the control circuit 68 can stop the operation of the noise suppression circuit 60C of the active noise canceller 60.

[0089] When the processing of step (4) is completed, the control circuit 68 proceeds to step (5).

[0090] (5) Sending diagnostic results The control circuit 68 transmits the diagnosis result of the abnormality diagnosis in step (3) to the control circuit 33 of the power conversion device 30 via a predetermined communication line.

[0091] (6) Receiving diagnostic results The control circuit 33 of the power conversion device 30 receives the diagnosis result transmitted in step (5).

[0092] When the process of step (6) is completed, the control circuit 33 proceeds to step (7).

[0093] (7) Determining the operating mode based on the diagnostic results The control circuit 33 determines the operation mode of the power conversion device 30 based on the diagnosis result of the abnormality diagnosis of the active noise canceller 60, and shifts to the determined operation mode.

[0094] Incidentally, the transition of the operation mode may include transitioning to the same operation mode as the current one, that is, maintaining the current operation mode.

[0095] For example, when the diagnosis result of the abnormality diagnosis of the active noise canceller 60 indicates that the active noise canceller 60 is normal, the control circuit 33 transitions to a normal mode for operating the motor 20 normally. On the other hand, when the diagnosis result of the abnormality diagnosis of the active noise canceller 60 indicates that the active noise canceller 60 is abnormal, the control circuit 33 transitions to an abnormality stop mode in which the operation of the motor 20 is kept stopped.

[0096] When the process of step (7) is completed, the control circuit 33 proceeds to step (8).

[0097] (8) Notification to the host device The control circuit 33 notifies the host device of information relating to the abnormality diagnosis of the active noise canceller 60.

[0098] The information related to the abnormality diagnosis includes, for example, information indicating the diagnosis result of the abnormality diagnosis, information indicating whether the diagnostic conditions are met, information related to the signal to be diagnosed, etc. The higher-level device is, for example, a control device that controls the overall operation of a device or system driven by the motor 20, such as the air conditioner 100 described below. This allows the higher-level device to notify the user or administrator of the device or system driven by the motor 20 of the information related to the abnormality diagnosis through a predetermined notification means such as an indicator, a display device, or a sound output device.

[0099] When the process of step (8) is completed, the series of operations of the power conversion system 1 relating to the abnormality diagnosis of the active noise canceller 60 is completed.

[0100] [Power conversion system according to comparative example] Next, a power conversion system 1c according to a comparative example will be described with reference to Fig. 2. The influence of a surge current caused by a lightning strike in the power conversion system 1c will be described.

[0101] FIG. 2 is a diagram showing a power conversion system 1c according to a comparative example.

[0102] The power conversion system 1c according to the comparative example differs from the above-described power conversion system 1 in that the active noise canceller 60 is replaced with an active noise canceller 60c, specifically, in that a circuit breaker 67c is provided instead of the circuit breaker 67.

[0103] The circuit breaker 67c is provided on a power path 73 for supplying power from the driving power supply 70 to both the amplifier circuit 62 and the compensation circuit 63. This allows the circuit breaker 67c to cut off the power supply from the driving power supply 70 to both the amplifier circuit 62 and the compensation circuit 63.

[0104] The circuit breaker 67c has the same function as the circuit breaker 67 of the above-described power conversion system 1. As a result, when the result of the abnormality diagnosis indicates that there is an abnormality in the active noise canceller 60, the circuit breaker 67c is switched from the connected state to the disconnected state, thereby stopping the operation of the noise suppression circuit 60C.

[0105] [Effects of surge current during lightning strikes] Next, the influence of a surge current in the power conversion system 1 when a lightning strike occurs will be described with reference to FIGS.

[0106] For example, a surge caused by a lightning strike may enter the power conversion system 1 from the AC power supply 10. In this case, a surge voltage is applied in common mode, and a surge current may flow between the power lines PL1, PL2 and the ground GL through the active noise canceller 60.

[0107] In the active noise canceller 60, the surge current flows through the path along which current flows when a compensation current or a compensation voltage is output from the compensation circuit 63. For example, a surge current entering from the power line PL12 passes through the coupling capacitor 66, capacitor C1, diode D1, and output capacitor Co, and flows through a path leading to the ground GL. A surge current entering from the ground GL passes through the output capacitor Co, diode D2, capacitor C2, and coupling capacitor 66, and reaches the power line PL12. Therefore, a voltage rise in capacitor C1 or capacitor C2 due to the surge current may cause part of the surge current to enter the drive power supply 70 through the power paths 72 and 73.

[0108] In the power conversion system 1c according to the comparative example, since the circuit breaker 67c is provided in the power path 73, a part of the surge current flowing through the compensation circuit 63 may flow into the power paths 72 and 73 and then into the circuit breaker 67c. Therefore, in consideration of the flow of the surge current, it becomes necessary to prepare the circuit breaker 67c with a relatively large current capacity. As a result, the adoption of the circuit breaker 67c with a relatively large current capacity may lead to an increase in the cost of the power conversion system 1.

[0109] In contrast, in the power conversion system 1 according to this embodiment, a circuit breaker 67 is provided in the power path 71 that supplies power only to the amplifier circuit 62, in parallel with the compensation circuit 63 through which the surge current flows. As a result, the surge current is less likely to flow through the circuit breaker 67, and the current capacity required for the circuit breaker 67 can be relatively small. This makes it possible to suppress an increase in the cost of the power conversion system 1 due to measures to deal with the surge current.

[0110] [Other examples of power conversion systems] Next, another example of the power conversion system 1 will be described.

[0111] The configuration, operation, etc. of the power conversion system 1 according to the above-described embodiment may be modified or changed as appropriate. Hereinafter, examples in which the configuration, operation, etc. of the power conversion system 1 according to the above-described embodiment are modified or changed will be referred to as "variant examples" for convenience.

[0112] For example, in the power conversion system 1 of the above-described embodiment, the AC power supply 10 may supply single-phase AC to the power conversion system 1 instead of three-phase AC.

[0113] Furthermore, in the power conversion system 1 of the above-described embodiment and its modified examples, the power conversion circuit 30C may have a smoothing circuit provided in the DC link between the rectifier circuit 31 and the inverter circuit 32, including a smoothing capacitor, a smoothing inductor, etc.

[0114] In the power conversion system 1 of the above-described embodiment and its modifications, the functions of the control circuit 33 may be realized by a plurality of circuits. For example, among the functions of the control circuit 33, the function of performing processing for diagnosing an abnormality in the active noise canceller 60 may be realized by a diagnostic circuit separate from the control circuit 33.

[0115] Furthermore, in the power conversion system 1 of the above-described embodiment and its modified examples, the coil 51 may be omitted, and the harness corresponding to the power line PL1 may simply be inserted into the toroidal core around which the coil 52 is wound. In this case, the harness corresponding to the power line PL1 is inserted into the toroidal core with the same polarity as in Fig. 1, specifically, with a polarity such that a current flows in the coil 52 in the opposite direction to the direction of the current flowing in the power line PL1 in the figure.

[0116] Furthermore, in the power conversion system 1 of the above-described embodiment and its modified examples, the noise detection means 50 may apply a known method (see, for example, Japanese Patent No. 5528543 and Japanese Patent No. 7309067) to detect common mode noise via a capacitor.

[0117] In the power conversion system 1 of the above-described embodiment and its modified examples, the filter circuit 61 may be omitted. In this case, the detection signal output from the noise detection means 50 is input to the amplifier circuit 62.

[0118] Furthermore, in the power conversion system 1 of the above-described embodiment and its modifications, the function of the amplifier circuit 62 may be realized by a microcomputer. In this case, the amplifier circuit 62 is omitted, and the detection signal of the noise detection means 50 or the signal output from the filter circuit 61 is input to the microcomputer. The microcomputer then generates a signal representing the waveform of a compensation current or a compensation voltage based on the input signal, and inputs the signal to the compensation circuit 63. For example, a microcomputer included in the control circuit 68 instead of the amplifier circuit 62, or provided separately from the control circuit 68, outputs a signal representing the waveform of a compensation current or a compensation voltage based on the detection signal of the noise detection means 50 or the signal output from the filter circuit 61.

[0119] Furthermore, in the power conversion system 1 of the above-described embodiment and its modifications, the function of the amplifier circuit 62 may be transferred to outside the active noise canceller 60. In this case, the amplifier circuit 62 is omitted. For example, a detection signal from the noise detection means 50 or a signal output from the filter circuit 61 is input to the control circuit 33 of the power conversion device 30 via a predetermined communication line. Then, the control circuit 33 generates a signal representing the waveform of a compensation current or a compensation voltage based on the input signal and transmits it to the active noise canceller 60 via the predetermined communication line. The signal representing the waveform of the compensation current or the compensation voltage is input to the compensation circuit 63.

[0120] In the power conversion system 1 of the above-described embodiment and its modifications, the diodes D1 and D2 of the compensation circuit 63 may be omitted.

[0121] In the power conversion system 1 of the above-described embodiment and its modified examples, either the amplifier circuit 62 or the compensation circuit 63 may be omitted.

[0122] In the power conversion system 1 of the above-described embodiment and its modified examples, the output section 64 may have, in addition to the output capacitor Co, a resistor connected in series thereto.

[0123] In the power conversion system 1 of the above-described embodiment and its modified examples, the output capacitor Co of the output unit 64 may be omitted. In this case, the output unit 64 may connect the compensation circuit 63 to the ground GL via a resistor, or may connect the compensation circuit 63 directly to the ground GL.

[0124] In the power conversion system 1 of the above-described embodiment and its modifications, the output unit 64 may be configured to output a compensation current or a compensation voltage to the power line PL12.

[0125] Furthermore, in the power conversion system 1 of the above-described embodiment and its variations, the output unit 64 may apply a known method (see, for example, Japanese Patent No. 5528543 or Japanese Patent No. 7309067) to output a compensation current or a compensation voltage to the power line PL1 by magnetic coupling. In this case, the output unit 64 includes a primary coil that is magnetically coupled to a harness corresponding to the power line PL1 or the ground GL, and a toroidal core around which the primary coil is wound, and the harness corresponding to the power line PL1 or the ground GL is inserted into the toroidal core. Furthermore, the harness corresponding to the power line PL1 or the ground GL may have a coil wound around the toroidal core.

[0126] Furthermore, in the power conversion system 1 of the above-described embodiment and its modifications, the functions of the control circuit 68 may be realized by a plurality of circuits. For example, among the functions of the control circuit 68, the function of performing processing for diagnosing an abnormality in the active noise canceller 60 may be realized by a diagnostic circuit separate from the control circuit 68.

[0127] In the power conversion system 1 of the above-described embodiment and its modified examples, the driving power supply 70 may be included in the active noise canceller 60.

[0128] In addition, in the power conversion system 1 of the above-described embodiment and its modified examples, the process of step (2) of diagnosing an abnormality in the active noise canceller 60, or the processes of steps (2) and (3), may be executed by the control circuit 33 of the power conversion device 30.

[0129] Furthermore, in the power conversion system 1 of the above-described embodiment and its modified examples, some or all of the functions for performing processing for diagnosing abnormalities in the active noise canceller 60 may be provided external to the power conversion device 30 or the active noise canceller 60. In this case, some or all of the functions for performing processing for diagnosing abnormalities in the active noise canceller 60 may be provided external to the device or system in which the power conversion system 1 is incorporated, i.e., the device or system driven by the motor 20. For example, some or all of the processing for diagnosing abnormalities in the active noise canceller 60 may be performed by an external diagnostic device that is provided external to the power conversion system 1 and is capable of communicating with the power conversion system 1.

[0130] [Application example of power conversion system] Next, an application example of the power conversion system 1 according to this embodiment will be described with reference to Fig. 3. Specifically, an air conditioner 100 in which the power conversion system 1 according to this embodiment is installed will be described.

[0131] FIG. 3 is a diagram showing an example of a refrigerant circuit of the air conditioner 100. As shown in FIG.

[0132] 1, the air conditioner 100 includes an outdoor unit 110, an indoor unit 120, and refrigerant paths 130 and 140. The air conditioner 100 operates a refrigeration cycle made up of the outdoor unit 110, the indoor unit 120, the refrigerant paths 130 and 140, etc., to adjust the temperature, humidity, etc., of the room in which the indoor unit 120 is installed.

[0133] The outdoor unit 110 is placed outside a building whose temperature and other conditions are to be adjusted. The outdoor unit 110 is connected to one end of each of the refrigerant paths 130 and 140, and draws in the refrigerant from one of the refrigerant paths 130 and 140 and discharges the refrigerant to the other.

[0134] The indoor unit 120 is placed in a room of a building where the temperature, etc., is to be adjusted. The indoor unit 120 is connected to the other end of each of the refrigerant paths 130, 140, and draws in refrigerant from one of the refrigerant paths 130, 140 and discharges the refrigerant to the other.

[0135] The refrigerant paths 130, 140 are configured by, for example, pipes, and connect the outdoor unit 110 and the indoor unit 120 so that the refrigerant can circulate between the outdoor unit 110 and the indoor unit 120.

[0136] The outdoor unit 110 includes refrigerant paths L1 to L6, oil paths L7 and L8, a four-way switching valve 111, an accumulator 112, a compressor 113, an oil separator 114, an outdoor heat exchanger 115, an outdoor expansion valve 116, and a fan 117.

[0137] The refrigerant paths L1 to L6 are configured as, for example, pipes.

[0138] The refrigerant path L1 connects one end of the refrigerant path 130 outside the outdoor unit 110 to the four-way switching valve 111.

[0139] The refrigerant path L2 connects the four-way switching valve 111 and the inlet of the compressor 113. The refrigerant path L2 includes refrigerant paths L21 and L22.

[0140] The refrigerant path L21 connects the four-way switching valve 111 and the accumulator 112. The refrigerant path L22 connects the accumulator 112 and the inlet of the compressor 113.

[0141] The refrigerant path L3 connects the four-way switching valve 111 and the outlet of the compressor 113. The refrigerant path L3 includes refrigerant paths L31 and L32.

[0142] The refrigerant path L31 connects the outlet of the compressor 113 and the oil separator 114. The refrigerant path L32 connects the four-way switching valve 111 and the oil separator 114.

[0143] The refrigerant path L4 connects the four-way switching valve 111 and the outdoor heat exchanger 115.

[0144] The refrigerant path L5 connects the outdoor heat exchanger 115 and the outdoor expansion valve 116.

[0145] The refrigerant path L6 connects one end of the refrigerant path 140 outside the outdoor unit 110 to the outdoor expansion valve 116.

[0146] The oil path L7 is configured as, for example, a pipe line, and is used to allow the oil separated by the oil separator 114 to flow into the refrigerant path L22 and return the oil to the compressor 113 through the refrigerant path L22.

[0147] Note that the oil passing through the oil path L7 may contain, for example, a liquid-phase refrigerant (hereinafter referred to as "liquid refrigerant") dissolved therein. That is, not only oil but also liquid refrigerant flows through the oil path L7.

[0148] The oil path L8 is configured as, for example, a pipe line, and is used to allow oil containing liquid refrigerant separated by the accumulator 112 to flow into the refrigerant path L22 and return it to the compressor 113 through the refrigerant path L22.

[0149] The four-way switching valve 111 reverses the flow of circulating refrigerant when the air conditioner 100 is in cooling operation and when it is in heating operation.

[0150] During cooling operation of the air conditioner 100, the four-way switching valve 111 connects the paths indicated by the solid lines in Fig. 1. Specifically, during cooling operation of the air conditioner 100, the four-way switching valve 111 connects refrigerant path L1 and refrigerant path L2, and refrigerant path L3 and refrigerant path L4.

[0151] On the other hand, when the air conditioner 100 is in heating operation, the four-way switching valve 111 connects the paths indicated by the dotted lines in Fig. 1. Specifically, when the air conditioner 100 is in heating operation, the four-way switching valve 111 connects the refrigerant path L4 to the refrigerant path L2, and the refrigerant path L1 to the refrigerant path L3.

[0152] The accumulator 112 separates the liquid refrigerant contained in the refrigerant drawn from the refrigerant path L21, and discharges the refrigerant from which some or all of the liquid refrigerant has been removed to the refrigerant path L22. The liquid refrigerant separated in the accumulator 112 contains oil. The accumulator 112 is provided with an oil discharge port connected to the oil path L8, and the separated oil containing the refrigerant flows out through the oil discharge port into the oil path L8 and is returned to the compressor 113 through the oil path L8 and the refrigerant path L22.

[0153] The compressor 113 is driven by the motor 20, draws in refrigerant from the refrigerant path L22, compresses it to high pressure, and discharges it to the refrigerant path L31. In this way, the power conversion system 1 can control the operation of the compressor 113 by driving the motor 20.

[0154] During cooling operation of the air conditioner 100, high-temperature, high-pressure refrigerant compressed by the compressor 113 flows into the outdoor heat exchanger 115 via refrigerant paths L3 and L4.

[0155] On the other hand, during heating operation of the air conditioner 100, the high-temperature, high-pressure refrigerant compressed by the compressor 113 flows through refrigerant path L3 and refrigerant path L1 into refrigerant path 130 outside the outdoor unit 110. Then, the high-temperature, high-pressure refrigerant flows into the indoor unit 120 through refrigerant path 130.

[0156] The oil separator 114 separates oil from the refrigerant flowing in from the refrigerant path L31, and discharges the refrigerant from which some or all of the oil has been separated and removed into the refrigerant path L32. The oil separator 114 is also provided with an oil outlet connected to the oil path L7, and the oil separated from the refrigerant flows into the oil path L7 through the oil outlet and is returned to the compressor 113 through the oil path L7 and the refrigerant path L22.

[0157] The outdoor heat exchanger 115 exchanges heat between the outside air and the refrigerant passing through the interior thereof. Specifically, the outdoor heat exchanger 115 is provided with a fan 117, and the outdoor heat exchanger 115 exchanges heat between the outside air blown by the fan 117 and the refrigerant flowing through the interior thereof.

[0158] During cooling operation of the air conditioner 100, the outdoor heat exchanger 115 causes the high-temperature, high-pressure refrigerant compressed by the compressor 113, which flows in from the refrigerant path L4, to radiate heat to the outside air, and causes the condensed and liquefied refrigerant (liquid refrigerant) to flow out into the refrigerant path L5.

[0159] Furthermore, during heating operation of the air conditioner 100, the outdoor heat exchanger 115 causes the low-temperature, low-pressure liquid refrigerant flowing in from the refrigerant path L5 to absorb heat from the outside air, and causes the evaporated refrigerant to flow into the refrigerant path L4.

[0160] The outdoor expansion valve 116 is closed to a predetermined degree during heating operation of the air conditioner 100, and reduces the pressure of the refrigerant (liquid refrigerant) flowing in from refrigerant path L6 to a predetermined level. On the other hand, during cooling operation of the air conditioner 100, the outdoor expansion valve 116 is fully open, and allows the refrigerant (liquid refrigerant) to pass from refrigerant path L5 to refrigerant path L6. The outdoor expansion valve 116 is, for example, a solenoid valve.

[0161] The indoor unit 120 includes an indoor expansion valve 121 , an indoor heat exchanger 122 , and a fan 123 .

[0162] During cooling operation of the air conditioner 100, the indoor expansion valve 121 is closed to a predetermined opening degree and reduces the pressure of the supercooled liquid refrigerant flowing in from the refrigerant path 140 to a predetermined pressure. On the other hand, during heating operation of the air conditioner 100, the indoor expansion valve 121 is fully open and allows the refrigerant (liquid refrigerant) flowing out from the indoor heat exchanger 122 to pass toward the refrigerant path 140. The indoor expansion valve 121 is, for example, a solenoid valve.

[0163] The indoor heat exchanger 122 exchanges heat between the indoor air and the refrigerant passing through it. Specifically, the action of the fan 123 mounted in the indoor unit 120 causes the indoor air to pass around the indoor heat exchanger 122, promoting heat exchange with the refrigerant inside the indoor heat exchanger 122. Then, the action of the fan 123 causes the indoor air that has exchanged heat with the refrigerant inside the indoor heat exchanger 122 to be sent out of the indoor unit 120, thereby realizing cooling or heating of the room.

[0164] When the air conditioner 100 is in cooling operation, the indoor heat exchanger 122 causes the low-temperature, low-pressure liquid refrigerant decompressed by the indoor expansion valve 121 to absorb heat from the indoor air, thereby lowering the temperature of the indoor air.

[0165] On the other hand, during heating operation of the air conditioner 100, the indoor heat exchanger 122 causes the high-temperature, high-pressure refrigerant flowing in from the outdoor unit 110 through the refrigerant path 130 to radiate heat to the indoor air, thereby raising the temperature of the indoor air.

[0166] In this way, in this example, the power conversion system 1 according to this embodiment is applied to the air conditioner 100 by being mounted on the air conditioner 100.

[0167] The power conversion system 1 according to this embodiment may be applied to a refrigeration device other than the air conditioner 100.

[0168] [Effect] Next, the operation of the power conversion system and the air conditioner according to this embodiment will be described.

[0169] In a first aspect of this embodiment, a power conversion system includes a power conversion circuit, a noise suppression circuit, a drive power supply, and a cutoff means. The power conversion system is, for example, the power conversion system 1 described above. The power conversion circuit is, for example, the power conversion circuit 30C included in the power conversion device 30 described above. The noise suppression circuit is, for example, the noise suppression circuit 60C included in the active noise canceller 60 described above. The drive power supply is, for example, the drive power supply 70 described above. The cutoff means is, for example, the circuit breaker 67 described above. Specifically, the power conversion circuit is connected to an AC power supply through a power line. The AC power supply is, for example, the AC power supply 10 described above. The power line is, for example, the power line PL1 described above. The noise suppression circuit outputs a compensation current or a compensation voltage to the propagation path including the power line so as to suppress common-mode noise flowing in the propagation path. The propagation path is, for example, a path including the power lines PL1 and PL2 described above and a ground GL. The drive power supply supplies power to drive the noise suppression circuit. The noise suppression circuit includes a first circuit and a second circuit. The first circuit is, for example, the amplifier circuit 62 described above. The second circuit is, for example, the compensation circuit 63. More specifically, the first circuit is supplied with power from the drive power supply. The second circuit is supplied with power from the drive power supply in parallel with the first circuit, and the current supplied from the drive power supply when the compensation current or the compensation voltage is output to the propagation path is larger than that supplied to the first circuit. The cutoff means is disposed in a power path that supplies power from the drive power supply to only the first circuit of the first and second circuits, and cuts off the supply of power to the first circuit. The power path is, for example, the power path 71 described above.

[0170] As a result, under the assumption that power from the driving power supply is supplied in parallel to the first circuit and the second circuit, the interrupting means is provided only in the power path that supplies power to the first circuit, not in the second circuit through which current flows when a compensation current or a compensation voltage is output. Therefore, in the power conversion system, for example, a surge current due to a lightning strike is likely to flow in the second circuit through which current flows when a compensation current or a compensation voltage is output, so the surge current due to a lightning strike is less likely to flow in the interrupting means. Therefore, the power conversion system can reduce the current capacity required for the interrupting means that interrupts the power supply from the driving power supply to the active noise suppression circuit.

[0171] In a second aspect of this embodiment, a power conversion system includes a power conversion circuit, a noise suppression circuit, a drive power supply, and a cutoff means. The power conversion system is, for example, the power conversion system 1 described above. The power conversion circuit is, for example, the power conversion circuit 30C described above. The noise suppression circuit is, for example, the noise suppression circuit 60C described above. The drive power supply is, for example, the drive power supply 70 described above. The cutoff means is, for example, the circuit breaker 67 described above. Specifically, the power conversion circuit is connected to an AC power supply through a power line. The AC power supply is, for example, the AC power supply 10 described above. The power line is, for example, the power line PL1 described above. The noise suppression circuit outputs a compensation current or a compensation voltage to the propagation path including the power line so as to suppress common-mode noise flowing in the propagation path. The propagation path is, for example, a path including the power lines PL1 and PL2 described above and a ground GL. The drive power supply supplies power to drive the noise suppression circuit. The noise suppression circuit includes a first circuit and a second circuit. The first circuit is, for example, the amplifier circuit 62 described above. The second circuit is, for example, the compensation circuit 63 described above. More specifically, the first circuit receives power from the drive power supply and generates a signal representing the waveform of the compensation current or the compensation voltage based on a detection signal from a detector that detects the common-mode noise. The signal representing the waveform of the compensation current or the compensation voltage is a signal indicating the amplitude and phase for each frequency of the waveform of the compensation current or the compensation voltage output from the second circuit. The signal representing the waveform of the compensation current or the compensation voltage is, for example, a current or voltage waveform signal having the same phase for each frequency and a smaller amplitude than the waveform of the compensation current or the compensation current output from the second circuit. The second circuit receives power from the drive power supply in parallel with the first circuit and outputs the compensation current or the compensation voltage based on the signal generated by the first circuit. The cutoff means is disposed on a power path that supplies power from the drive power supply to only the first circuit of the first and second circuits, and cuts off the supply of power to the first circuit. The power path is, for example, the above-mentioned power path 71.

[0172] As a result, under the assumption that power from the driving power supply is supplied in parallel to the first circuit and the second circuit, the interrupting means is provided only in the power path that supplies power to the first circuit, not in the second circuit through which current flows when a compensation current or a compensation voltage is output. Therefore, in the power conversion system, for example, a surge current due to a lightning strike is likely to flow in the second circuit through which current flows when a compensation current or a compensation voltage is output, so the surge current due to a lightning strike is less likely to flow in the interrupting means. Therefore, the power conversion system can reduce the current capacity required for the interrupting means that interrupts the power supply from the driving power supply to the active noise suppression circuit.

[0173] In addition, in a third aspect of the present embodiment, on the premise of the first or second aspect described above, the first circuit may include an operational amplifier.

[0174] This allows the power conversion system to output a compensation current or a compensation voltage for suppressing common-mode noise from the noise suppression circuit using the first circuit including the operational amplifier.

[0175] In addition, in a fourth aspect of the present embodiment, on the premise of any one of the first to third aspects described above, the second circuit may include a push-pull circuit including a transistor.

[0176] This allows the power conversion system to output a compensation current or a compensation voltage for suppressing common-mode noise from the noise suppression circuit using a push-pull circuit including a transistor.

[0177] In addition, in a fifth aspect of the present embodiment, based on any one of the first to fourth aspects described above, a noise filter may be provided in the power line between a point where the noise suppression circuit is connected and the power conversion circuit.

[0178] As a result, the power conversion system is provided with a noise suppression circuit in front of the noise filter in the power line between the AC power source and the power conversion circuit, and is able to suppress the inflow of surge current into the interrupter, under the assumption that surge current during a lightning strike is likely to flow into the noise suppression circuit.

[0179] In a sixth aspect of the present embodiment, based on any one of the first to fifth aspects, the power conversion circuit may include a switching element, and a wide bandgap semiconductor may be used for the switching element.

[0180] This allows the power conversion system to suppress common modes that accompany the switching operation of the wide bandgap semiconductor.

[0181] In addition, in a seventh aspect of the present embodiment, an air conditioner may include the power conversion device of any one of the first to sixth aspects described above. The air conditioner is, for example, the air conditioner 100 described above.

[0182] As a result, the power conversion system can be applied to an air conditioner, and common mode noise can be suppressed when the motor that drives the air conditioner is in operation.

[0183] Although the embodiments have been described above, it will be understood that various changes in form and details can be made without departing from the spirit and scope of the claims. [Explanation of symbols]

[0184] 1 Power Conversion System 10 AC power supply 20 Motor 30 Power conversion device 30C power conversion circuit 31 Rectifier circuit 32 Inverter circuit 33 Control circuit 40 Noise Filter 41 Common mode choke coil 42 Y capacitors 50 Noise detection means 51 Coil 52 Coil 60 Active Noise Canceller 60C noise suppression circuit 61 Filter Circuit 62 Amplifier circuit 63 Compensation circuit 64 Output section 65 Power supply circuit 66 Coupling capacitor 67 Circuit Breaker 68 Control Circuit 70 Drive power supply 71 Power Path 72 Power Path 100 Air conditioner 621 Operational Amplifier C1, C2 capacitors Co Output Capacitor D1, D2 diodes GL Grand PL1,PL2 power line PL11,PL12,PL13 Power line Tr1, Tr2 transistors

Claims

1. a power conversion circuit (30C) connected to the AC power supply (10) through a power line (PL1); a noise suppression circuit (60C) that outputs a compensation current or a compensation voltage to a propagation path including the power line (PL1) so as to suppress common mode noise flowing in the propagation path; a driving power supply (70) for supplying power for driving the noise suppression circuit (60C); and a blocking means (67), The noise suppression circuit (60C) includes a first circuit (62) to which power is supplied from the drive power supply (70), and a second circuit (63) to which power is supplied from the drive power supply (70) in parallel with the first circuit (62), and to which a current supplied from the drive power supply (70) is greater than that supplied to the first circuit (62) when the compensation current or the compensation voltage is output to the propagation path, The cutoff means (67) is disposed in a power path (71) that supplies power from the drive power source (70) only to the first circuit (62) of the first circuit (62) and the second circuit (63), and cuts off the supply of power to the first circuit (62). Power conversion systems.

2. a power conversion circuit (30C) connected to the AC power supply (10) through a power line (PL1); a noise suppression circuit (60C) that outputs a compensation current or a compensation voltage to a propagation path including the power line (PL1) so as to suppress common mode noise flowing in the propagation path; a driving power supply (70) for supplying power for driving the noise suppression circuit (60C); and a blocking means (67), The noise suppression circuit (60C) includes a first circuit (62) that receives power from the drive power supply (70) and generates a signal representing a waveform of the compensation current or the compensation voltage based on a detection signal from a detection means that detects the common mode noise, and a second circuit (63) that receives power from the drive power supply (70) in parallel with the first circuit (62) and outputs the compensation current or the compensation voltage based on the signal generated by the first circuit (62), The cutoff means (67) is disposed in a power path (71) that supplies power from the drive power source (70) only to the first circuit (62) of the first circuit (62) and the second circuit (63), and cuts off the supply of power to the first circuit (62). Power conversion systems.

3. The first circuit (62) includes an operational amplifier (621). The power conversion system according to claim 1 or 2.

4. The second circuit (63) includes a push-pull circuit including transistors (Tr1, Tr2). The power conversion system according to claim 1 or 2.

5. a noise filter (40) is provided on the power line (PL1) between a point where the noise suppression circuit (60C) is connected and the power conversion circuit (30C); The power conversion system according to claim 1 or 2.

6. The power conversion circuit (30C) includes a switching element, A wide band gap semiconductor is used for the switching element. The power conversion system according to claim 1 or 2.

7. The power conversion system (1) according to claim 1 or 2, Air conditioner.

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