Power conversion system, air conditioner

Abstract

The present disclosure provides a technology capable of suppressing a common-mode noise level when performing diagnosis related to an abnormality of a noise suppression device. For example, a power conversion system (1) according to an embodiment of the present disclosure includes: a power conversion device (30) that drives a motor (20) using power supplied from an alternating-current power source (10) by causing a switching element to perform a switching operation; a noise detection unit (50) that detects common-mode noise flowing in a path including a power line (PL1, PL2) in association with the switching operation of the switching element, and outputs a detection signal; an active noise canceller (60) that outputs a compensation current or a compensation voltage to the path based on the detection signal output from the noise detection unit, and suppresses the common-mode noise; and a control circuit (67) that performs diagnosis related to an abnormality of the active noise canceller (60) based on a signal related to a state of the common-mode noise when the switching operation not associated with a rotational operation of the motor (20) is performed by the power conversion device (30).

Description

Technical Field

[0001] This disclosure relates to a power conversion system, etc. Background Technology

[0002] Previously, a technique for suppressing common-mode noise was known in a power conversion system comprising a power conversion device that uses power supplied from an AC power source through a power line and drives a motor by switching action of a switching element (for example, see Patent Document 1).

[0003] Patent document 1 discloses an active noise suppression technology that reduces common-mode noise by detecting common-mode noise and outputting a compensation current or compensation voltage to the path through which the common-mode noise flows.

[0004] <Prior art documents> <Patent Documents> Patent Document 1: Japanese Patent No. 3044650 Summary of the Invention <Problem to be solved by this invention> However, there are situations where diagnostics related to malfunctions in noise suppression devices can be performed. For example, malfunction-related diagnostics can be conducted by determining whether common-mode noise is being adequately suppressed.

[0005] However, for example, in cases where diagnostics related to noise suppression device malfunctions are performed during the normal operation of load devices such as motors, the load device may operate as usual even when the noise suppression device exhibits abnormalities or signs of abnormality. Consequently, common-mode noise is not properly suppressed, and as a result, common-mode noise may leak into other devices connected to the power conversion system.

[0006] The purpose of this disclosure is to provide a technique for suppressing common-mode noise levels during diagnostics related to anomalies in noise suppression devices.

[0007] <Methods for solving problems> In the first aspect of this disclosure, a power conversion system is provided, which comprises: A power conversion device that is connected to an AC power source and a motor via a power line, and drives the motor using power supplied from the AC power source by switching a switching element. The detection unit detects common-mode noise flowing in the path containing the power line accompanying the switching action of the switching element, and outputs a detection signal. A noise suppression device, which, based on a detection signal output from the detection unit, outputs a compensation current or compensation voltage to the path to suppress the common-mode noise; and The first circuit performs a diagnosis related to the anomaly of the noise suppression device based on a signal related to the state of the common-mode noise when the switching action is performed by the power conversion device without the rotation of the motor.

[0008] According to this method, the power conversion system can suppress the common-mode noise level when performing diagnostics related to anomalies in the noise suppression device.

[0009] Furthermore, in the second aspect of this disclosure, based on the first aspect described above, it can be configured as follows: The signal associated with the state of the common-mode noise is the detection signal output from the detection unit, or a signal originating from the detection signal.

[0010] Furthermore, in the third aspect of this disclosure, based on the first or second aspect described above, it can be configured as follows: The noise suppression device includes the first circuit. The first circuit uses a signal related to the state of the common-mode noise when the switching action is performed by the power conversion device without the rotation of the motor to determine whether the conditions related to the diagnosis are met, and performs the diagnosis based on the determination result.

[0011] Furthermore, in the fourth aspect of this disclosure, based on the first or second aspect described above, it can be configured as follows: The noise suppression device includes a second circuit. The power conversion device includes the first circuit. The second circuit uses a signal related to the common-mode noise state during the switching action of the power conversion device without the rotation of the motor to determine whether the conditions related to the diagnosis are met. The first circuit performs the diagnosis based on the determination result of the second circuit.

[0012] Furthermore, in the fifth aspect of this disclosure, based on either the first or second aspect described above, it can be configured as follows: The power conversion device includes the first circuit. The first circuit uses a signal related to the state of the common-mode noise when the switching action is performed by the power conversion device without the rotation of the motor to determine whether the conditions related to the diagnosis are met, and performs the diagnosis based on the determination result.

[0013] Furthermore, in the sixth aspect of this disclosure, based on any of the first to fifth aspects described above, it can be configured as follows: The device includes a third circuit that controls the power conversion device for the purpose of the diagnostics, performing the switching action without the rotation of the motor.

[0014] Furthermore, in the seventh aspect of this disclosure, based on any of the first to sixth aspects described above, it can be configured as follows: The power conversion device performs the switching action without the motor rotating, by applying a DC voltage to the motor.

[0015] Furthermore, in the eighth aspect of this disclosure, based on any one of the aspects 1 to 6 described above, it can be configured as follows: The motor is driven by a three-phase AC motor. The power conversion device performs the switching action without the motor rotating, by applying AC voltage to two of the three phases of the motor.

[0016] Furthermore, in the ninth aspect of this disclosure, based on the second aspect described above, it can be configured to possess: An amplification circuit that amplifies the detection signal output from the detection unit, or the signal output from a filter circuit through which the detection signal passes; and The compensation circuit outputs the compensation current or the compensation voltage based on the signal output from the amplifier circuit. When the switching action is performed by the power conversion device without the rotation of the motor, the amplification circuit or the compensation circuit increases the amplification degree compared to when the switching action is performed by the power conversion device with the rotation of the motor.

[0017] Furthermore, in the tenth aspect of this disclosure, based on any one of the aspects 1 to 9 described above, it can be configured as follows: The noise suppression device includes: A filter circuit that allows the detection signal output from the detection unit to pass through and removes specific frequency components; An amplifier circuit that amplifies the signal output from the filter circuit; and A compensation circuit that outputs the compensation current or the compensation voltage based on the signal output from the amplifier circuit.

[0018] Furthermore, in the eleventh aspect of this disclosure, based on the second aspect described above, it can be configured as follows: The noise suppression device includes: A filter circuit that allows the detection signal output from the detection unit to pass through and removes specific frequency components; An amplifier circuit that amplifies the signal output from the filter circuit; and The compensation circuit outputs the compensation current or the compensation voltage based on the signal output from the amplifier circuit. The signal originating from the detection signal output from the detection unit is a signal output from the filter circuit, a signal output from the amplifier circuit, or a signal representing the compensation current or the compensation voltage output from the compensation circuit.

[0019] Furthermore, in the 12th aspect of this disclosure, based on any one of the aspects 1 to 11 described above, it can be configured as follows: The switching element uses a wide-bandgap semiconductor.

[0020] Furthermore, in the 13th aspect of this disclosure, an air conditioner is provided that has a power conversion system comprising any one of the above-described 1 to 12 aspects.

[0021] <The Effects of the Invention> According to the above embodiments, it is possible to suppress the common-mode noise level when performing diagnoses related to abnormalities of the noise suppression device. Attached Figure Description

[0022] Figure 1 This is a diagram illustrating an example of a power conversion system.

[0023] Figure 2 This is a sequence diagram illustrating the first example of the operation of a power conversion system.

[0024] Figure 3 This is a sequence diagram illustrating the second example of the operation of a power conversion system.

[0025] Figure 4 This is a sequence diagram illustrating the third example of the operation of a power conversion system.

[0026] Figure 5 This is a diagram showing an example of the refrigerant circuit of an air conditioner. Detailed Implementation

[0027] The embodiments will now be described with reference to the accompanying drawings.

[0028] [Structure of Power Conversion System] Reference Figure 1 The structure of the power conversion system 1 involved in this embodiment will be described.

[0029] Figure 1 This is a diagram illustrating an example of a power conversion system 1.

[0030] like Figure 1As shown, the power conversion system 1 uses power supplied from the AC power source 10 to drive the motor 20.

[0031] AC power source 10 supplies AC to power conversion system 1. In this example, AC power source 10 supplies three-phase AC (R-phase, S-phase, and T-phase) to power conversion system 1.

[0032] The motor 20 is driven by a three-phase AC output from the power conversion system 1. The motor 20 is, for example, a DC (Direct Current) brushless motor. Alternatively, the motor 20 can also be driven by other three-phase AC motors.

[0033] The power conversion system 1 includes power line PL1, power line PL2, power conversion device 30, noise filter 40, noise detection unit 50, active noise canceller 60, and drive power supply 70.

[0034] Power line PL1 connects the AC power source 10 and the power conversion device 30 via three power lines: R-phase, S-phase, and T-phase. Power line PL1 includes power lines PL11 to PL13.

[0035] The power line PL2 is electrically connected between the power conversion device 30 and the motor 20 via three power lines: U-phase, V-phase, and W-phase.

[0036] Power line PL11 is connected between AC power supply 10 and coil 51 via three power lines: R-phase, S-phase, and T-phase. Power line PL12 is connected between coil 51 and common-mode choke coil 41 of noise filter 40 via three power lines: R-phase, S-phase, and T-phase. Power line PL13 is connected between common-mode choke coil 41 and power conversion device 30 via three power lines: R-phase, S-phase, and T-phase.

[0037] The power conversion device 30 converts the AC power supplied through the power line PL1 into a three-phase AC power with a given frequency and a given voltage, and outputs it to the motor 20 through the power line PL2, thereby driving the motor 20.

[0038] The power conversion device 30 includes, for example, a rectifier circuit 31, an inverter circuit 32, and a control circuit 33.

[0039] The rectifier circuit 31 converts the three-phase AC (R-phase, S-phase, and T-phase) supplied via the power line PL13 into DC and outputs it to the DC link (also known as the "DC link"). The rectifier circuit 31 is, for example, a three-phase full-wave rectifier circuit using diodes.

[0040] Inverter circuit 32 converts the DC input from the rectifier circuit 31 and its DC link into a three-phase AC with a given frequency and a given voltage. Specifically, it converts the DC into U-phase, V-phase, and W-phase AC and outputs it. Inverter circuit 32 includes, for example, switching elements. By switching the elements, the DC is converted into a three-phase AC with a given frequency and a given voltage and output to the power line PL2.

[0041] Switching elements can be, for example, IGBTs (Insulated Gate Bipolar Transistors), MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors), or HEMTs (High Electron Mobility Transistors). These switching elements are primarily constructed of silicon (Si). Alternatively, they can be constructed primarily of wide-bandgap semiconductor materials. Examples of wide-bandgap semiconductor materials include silicon carbide (SiC), gallium nitride (GaN), gallium oxide (Ga2O3), and carbon (C). Furthermore, in addition to the switching elements, the inverter circuit 32 may also include a freewheeling diode composed of semiconductors connected in parallel with the switching elements.

[0042] The control circuit 33 performs control processing related to the power conversion device 30.

[0043] In addition, the control circuit 33 can also be used for other processing related to the power conversion system 1.

[0044] For example, control circuit 33 performs processing for diagnosis related to anomalies of active noise canceller 60 (hereinafter referred to as "anomaly diagnosis"). Anomaly diagnosis may include, for example, a diagnosis of whether or not an anomaly exists. Alternatively, anomaly diagnosis may also include a diagnosis of whether or not there are abnormal symptoms or a diagnosis of the degree of anomaly.

[0045] The function of the control circuit 33 can be implemented by hardware (circuit) in both hardware and software, or by a combination of hardware (e.g., integrated circuits (ICs)) and software. In the latter case, for example, the control circuit 33 is configured around a microcomputer that includes a CPU (Central Processing Unit), memory devices, auxiliary storage devices, and input / output interfaces.

[0046] Furthermore, the functions of the control circuit 33 can be implemented by multiple circuits. For example, the function of performing abnormality diagnosis for the active noise canceller 60 in the control circuit 33 can be implemented by a diagnostic circuit different from the control circuit 33.

[0047] The noise filter 40 is a passive noise suppression device for suppressing common-mode noise.

[0048] Common-mode noise occurs during the switching of the switching elements in the inverter circuit 32. Specifically, common-mode noise is generated because the noise accompanying the switching of the switching elements leaks to ground GL through the parasitic capacitance of the motor 20, the parasitic capacitance between the switching elements (not shown) and the heat sink of the power conversion device 30.

[0049] The noise filter 40 includes a common-mode choke coil 41 and a Y capacitor 42.

[0050] The common-mode choke coil 41 acts as an inductor to suppress the common-mode noise current (common-mode current) flowing in the power line PL1.

[0051] Y capacitor 42 serves to return the common-mode current flowing out to ground GL to the inverter circuit 32, which is a noise source. One end of Y capacitor 42 is connected to the power line PL13, and the other end is connected to ground GL.

[0052] Grounding GL is grounded. For example, it can be the housing of a device including the power conversion system 1. Alternatively, grounding GL can also be a dedicated reference potential line.

[0053] The noise detection unit 50 detects the common-mode noise current (common-mode current) or noise voltage (common-mode voltage). For example, ... Figure 1 As shown, the noise detection unit 50 detects the common-mode current of the power line PL1. The noise detection unit 50 has a circuit including the primary side of the coil 51 and a circuit including the secondary side of the coil 52.

[0054] Coil 51 is respectively installed on the R phase, S phase and T phase of the power line PL1.

[0055] Coil 52 is magnetically coupled to coil 51. Coil 52 outputs a detection signal corresponding to the common-mode noise of the power line PL1.

[0056] Coils 51 and 52 are wound on a core of the same magnetic material, such as... Figure 1 As indicated by the "·", they are configured to have opposite polarities. The core of the magnetic material used to wind coils 51 and 52 is, for example, a toroidal core, and the magnetic material is, for example, ferrite or permalloy. For example, in the case where the current flows to the right in coil 51, the current flows to the left in coil 52. That is, Figure 1The polarity indicated by the "·" is the polarity according to the direction of current flow.

[0057] For example, when a common-mode current flows through coil 51, a current proportional to the common-mode current is induced in coil 52. Thus, coils 51 and 52 function as current-sensing transformers for detecting the common-mode current. Additionally, the noise detection unit 50 can also detect common-mode noise at ground GL.

[0058] The active noise canceller 60 outputs a compensation current or compensation voltage to power line PL1, power line PL2, or ground GL based on the detection signal output from coil 52 of noise detection unit 50. The active noise canceller 60 includes a filter circuit 61, an amplifier circuit 62, a compensation circuit 63, an output section 64, a power supply circuit 65, a coupling capacitor 66, and a control circuit 67.

[0059] The filter circuit 61 allows the signal after removing a specific frequency component from the detection signal output from the coil 52 to pass through, and the output signal of the filter circuit 61 is input to the amplifier circuit 62.

[0060] Amplifier circuit 62 amplifies the signal output from filter circuit 61. Amplifier circuit 62 includes, for example, an operational amplifier. The signal output from amplifier circuit 62 is input to compensation circuit 63.

[0061] The power supply voltage of the operational amplifier is, for example, less than 2 / 3 of the DC link voltage (DC link voltage) Vdc of the power conversion circuit 30C. This is because, since 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) varies by 1 / 3, as long as the power supply voltage of the operational amplifier is within ±1 / 3 of the DC link voltage Vdc, the relationship between voltage Vcc and impedance can be ignored, and the common-mode noise caused by the switching operation of the inverter circuit 32 can be eliminated.

[0062] The signal output from amplifier circuit 62, representing the waveform of the compensation current or compensation voltage, is input to compensation circuit 63. The signal representing the waveform of the compensation current or compensation voltage is a signal indicating the amplitude and phase of each frequency in the waveform of the compensation current or compensation voltage output from compensation circuit 63. For example, the signal representing the waveform of the compensation current or compensation voltage output from amplifier circuit 62 is a current or voltage waveform signal with the same phase at each frequency and a small amplitude relative to the waveform of the compensation current or compensation voltage output from compensation circuit 63.

[0063] 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.

[0064] Transistor Tr1 is connected between one end of the drive power supply 70 and the output capacitor Co of the output section 64. Transistor Tr2 is connected between the other end of the drive power supply 70 and the output capacitor Co of the output section 64.

[0065] like Figure 1 As shown, in this example, transistor Tr1 is a PNP type and transistor Tr2 is an NPN type, with transistors Tr1 and Tr2 having opposite polarities. Therefore, transistors Tr1 and Tr2 form a push-pull circuit, which functions as an amplifier.

[0066] The bases of transistors Tr1 and Tr2 are connected to one end of coil 52 via amplifier circuit 62 and filter circuit 61, and the connection point of transistors Tr1 and Tr2 is connected to the other end of coil 52 via amplifier circuit 62 and filter circuit 61. Thus, transistors Tr1 and Tr2 perform opposite operations.

[0067] Diodes D1 and D2 are connected in anti-parallel to protect transistors Tr1 and Tr2.

[0068] The output unit 64 outputs the compensation current or compensation voltage from the compensation circuit 63 to the common-mode flow path. The output unit 64 includes an output capacitor Co.

[0069] One end of the output capacitor Co is connected to the connection point of transistors Tr1 and Tr2 in the compensation circuit 63, and the other end is connected to ground GL.

[0070] The power supply circuit 65 is connected to the drive power supply 70. The power supply circuit 65 includes capacitors C1 and C2.

[0071] Capacitors C1 and C2 are connected in series. The series connection of capacitors C1 and C2 is connected in parallel with the drive power supply 70 and the compensation circuit 63. In addition, the midpoint of capacitors C1 and C2 is connected to the coupling capacitor 66.

[0072] One end of the coupling capacitor 66 is connected to the power line PL12, and the other end is connected to the midpoint between capacitors C1 and C2.

[0073] The control circuit 67 performs control processing related to the active noise canceller 60.

[0074] In addition, the control circuit 67 can also perform abnormal diagnosis for the active noise canceller 60.

[0075] The function of the control circuit 67 can be implemented by hardware (circuit) in both hardware and software, or by a combination of hardware (e.g., integrated circuit) and software. In the latter case, for example, the control circuit 67 is configured around a microcomputer that includes a CPU, memory device, auxiliary storage device, and input / output interface.

[0076] Furthermore, the functions of control circuit 67 can also be implemented by multiple circuits. For example, the function of performing abnormality diagnosis for active noise canceller 60 in control circuit 67 can be implemented by a diagnostic circuit different from control circuit 67.

[0077] The drive power supply 70 supplies DC drive power to the active noise canceller 60.

[0078] The drive power supply 70 can be a DC power supply that can supply DC to the active noise canceller 60 on its own, or it can be a capacitor that uses the DC voltage of the DC link between the rectifier circuit 31 and the inverter circuit 32 of the power conversion circuit 30C as a power supply.

[0079] [Operation of the active noise canceller] Next, continue to refer to Figure 1 The operation of the active noise canceller is explained.

[0080] Furthermore, for simplicity, the suppression effect of the noise filter 40 on the common-mode current Ic will be ignored in this example.

[0081] The noise detection unit 50 detects the common-mode noise of the power line PL1 and drives transistors Tr1 and Tr2 via the filter circuit 61 and the amplifier circuit 62. Specifically, when the detection signal output from the coil 52 of the noise detection unit 50 is input to the base of transistors Tr1 and Tr2 via the filter circuit 61 and the amplifier circuit 62, it is amplified by transistors Tr1 and Tr2.

[0082] According to the common-mode current Ic Figure 1 When the flow direction of the arrow is indicated, transistor Tr1 is turned on. In this case, the compensation current Io is supplied from the drive power supply 70 and flows in a path from the positive terminal of the drive power supply 70 through capacitor C2, coupling capacitor 66, AC power supply 10, output capacitor Co, and the connection between transistor Tr1 and the negative terminal of the drive power supply 70. Thus, the reduced common-mode current Ig flows to the AC power supply 10 in the form of drawing the compensation current Io from the common-mode current Ic.

[0083] Additionally, when the common-mode current Ic is in accordance with... Figure 1When the current flows in the opposite direction to the arrow, transistor Tr2 is turned on. In this case, the compensation current Io is supplied from the drive power supply 70 and flows in the current path connecting the positive terminal of the drive power supply, transistor Tr2, output capacitor Co, AC power supply 10, coupling capacitor 66, capacitor C1, and the negative terminal of the drive power supply 70. That is, the compensation current Io flows in the direction opposite to the arrow. Figure 1 The flow is in the opposite direction to the arrow. Therefore, in the form of drawing compensation current Io from the common-mode current Ic, it flows in the same direction as... Figure 1 The common-mode current Ig, which is reduced in the opposite direction of the arrow, flows to the AC power supply 10.

[0084] In this way, the active noise canceller 60 can suppress the common-mode current Ig flowing to the AC power supply 10 by outputting a compensation current Io to the path through which the common-mode current Ic flows. Therefore, for example, the active noise canceller 60 can prevent the common-mode noise current from flowing out of the AC power supply 10 to peripheral devices and causing an impact.

[0085] [Example of the operation of a power conversion system] Next, refer to Figure 2 The first example of the operation of the power conversion system 1 related to the abnormal diagnosis of the active noise canceller 60 will be described.

[0086] Figure 2 This is a sequence diagram illustrating the first example of the operation of the power conversion system 1.

[0087] like Figure 2 As shown, in step S102, the control circuit 33 of the power conversion device 30 sets the operating mode of the power conversion device 30 to a diagnostic mode for abnormal diagnosis of the active noise canceller 60 at a given timing. The given timing is predetermined as a timing different from the normal operation of the motor 20. The given timing is, for example, when the motor 20 or the device or system containing the motor 20 starts or stops. When the motor 20 or the device driven by the motor 20 stops, it means when the motor 20 or the device driven by the motor 20 changes from an operating state to an operating stopped state.

[0088] The diagnostic mode is an operating mode in which the inverter circuit 32 is switched on and off without the motor 20 rotating. For example, in the diagnostic mode, the control circuit 33 switches the inverter circuit 32 on and off by applying a DC voltage to the motor 20. Alternatively, in the diagnostic mode, the control circuit 33 can also switch the inverter circuit 32 on and off by applying an AC voltage to two of the three phases (U, V, and W) of the motor 20. Thus, the control circuit 33 can switch the inverter circuit 32 on and off without rotating the motor 20.

[0089] Additionally, other functions can be activated simultaneously in conjunction with a diagnostic mode executed at a given time. For example, the control circuit 33 can switch to diagnostic mode and apply DC voltage to the motor 20 to switch the inverter circuit 32, thereby positioning the rotor of the motor 20. Furthermore, when the motor 20 drives the compressor 113 (described later), the control circuit 33 can also switch the inverter circuit 32 by applying AC voltage to two of the three phases of the motor 20, heating the refrigerant or oil through its heat generation. Additionally, the control circuit 33 can switch to diagnostic mode and apply AC voltage to two of the three phases of the motor 20 to switch the inverter circuit 32, causing the temperature of the switching elements and surrounding components to rise, thus suppressing condensation. Furthermore, the control circuit 33 can switch to diagnostic mode and apply AC voltage to two of the three phases of the motor 20 to switch the inverter circuit 32, causing the DC link of the power conversion device 30 to pulsate due to the AC frequency of the AC power supply 10. Therefore, the control circuit 33 can determine the state of the AC power supply 10 based on various detection values ​​during the pulsation of the DC link.

[0090] Furthermore, the control circuit 33 can also switch to diagnostic mode when a timer is set for switching the inverter circuit 32 without the motor 20 rotating, which is used to operate other functions. For example, when the motor 20 is started, the control circuit 33 switches to diagnostic mode when the timer for rotor positioning is set. Additionally, the control circuit 33 can switch to diagnostic mode when the compressor 113 is started, if the condition requiring preheating of refrigerant or oil is met. Furthermore, the control circuit 33 can switch to diagnostic mode when the power conversion device 30 is stopped, if the condition that condensation may occur on the switching elements and their surrounding components is met. Finally, the control circuit 33 can switch to diagnostic mode when a timer for determining the state of the AC power supply 10 is set.

[0091] When step S102 is completed, the control circuit 33 moves to step S104.

[0092] In step S104, the control circuit 33 sends a signal indicating that the operating mode of the power conversion device 30 has been changed to the diagnostic mode to the control circuit 67 of the active noise canceller 60 via a given communication line.

[0093] In step S106, the control circuit 67 of the active noise canceller 60 receives the signal sent from the control circuit 33 of the power conversion device 30 in step S104.

[0094] When step S106 is completed, control circuit 67 proceeds to step S108.

[0095] In step S108, the control circuit 67 acquires at least one of the detection signal output from the coil 52 of the noise detection unit 50 and a signal originating from the detection signal, and detects a physical quantity for diagnosis.

[0096] Signals originating from the detection signal output from coil 52 include, for example, signals output from filter circuit 61, signals output from amplifier circuit 62, signals representing compensation current or compensation voltage output from compensation circuit 63, and signals representing compensation current or compensation voltage output from output unit 64. The signals representing compensation current or compensation voltage are not limited to the compensation current or compensation voltage itself; for example, they include signals after converting the compensation current or compensation voltage into a relatively weak voltage. When there are multiple signals originating from the detection signal output from coil 52, two or more signals originating from the detection signal may be obtained. Hereinafter, the types of signals obtained in step S108 will sometimes be referred to as "signals of the diagnostic target" for convenience.

[0097] Diagnostic physical quantities are physical quantities represented by the signals of the object being diagnosed. Examples of diagnostic physical quantities include current or voltage.

[0098] When step S108 is completed, control circuit 67 proceeds to step S110.

[0099] In step S110, the control circuit 67 determines whether the diagnostic conditions related to the diagnostic physical quantities detected in step S108 are met.

[0100] The diagnostic conditions refer to the conditions related to the diagnosis of abnormalities in the active noise canceller 60. For example, the diagnostic conditions related to the physical quantity used for diagnosis are specified according to each type of signal of the diagnostic object obtained in step S108, and are conditions indicating whether the magnitude of the physical quantity used for diagnosis is above or below a threshold. This is because when the magnitude of the current or voltage corresponding to the detection signal output from coil 52 is large, the possibility of common-mode noise not being properly suppressed and the active noise canceller 60 malfunctioning increases.

[0101] When step S110 is completed, control circuit 67 proceeds to step S112.

[0102] In step S112, the control circuit 67 performs anomaly diagnosis of the active noise canceller 60 based on the result of the determination of whether the diagnostic conditions related to the diagnostic physical quantity are met in step S110.

[0103] For example, control circuit 67 performs anomaly diagnosis based on whether or not a diagnostic condition related to the diagnostic physical quantity is met at a certain point in time in the diagnostic mode. Alternatively, control circuit 67 can also perform anomaly diagnosis of the active noise canceller 60 by considering additional diagnostic conditions, such as the number of times or the cumulative time of the met diagnostic conditions related to the diagnostic physical quantity, in addition to whether the diagnostic conditions are met. For example, control circuit 67 performs anomaly diagnosis of the active noise canceller 60 based on whether the cumulative time or number of times the diagnostic conditions related to the diagnostic physical quantity are met within a specified period in the diagnostic mode exceeds a given threshold.

[0104] When step S112 is completed, control circuit 67 proceeds to step S114.

[0105] In step S114, the control circuit 67 sends the diagnosis result of the abnormality diagnosis in step S112 to the control circuit 33 of the power conversion device 30 through a given communication line.

[0106] In step S116, the control circuit 33 of the power conversion device 30 receives the diagnostic results sent in step S114.

[0107] When step S116 is completed, control circuit 33 proceeds to step S118.

[0108] In step S118, the control circuit 33 determines the operating mode of the power conversion device 30 based on the diagnostic results of the abnormality diagnosis of the active noise canceller 60, and switches to the determined operating mode.

[0109] For example, when the motor 20 is started, if the diagnostic result of the active noise canceller 60 indicates that the abnormality diagnosis is normal, the control circuit 33 switches to a normal mode for the motor 20 to operate normally. On the other hand, if the diagnostic result of the active noise canceller 60 indicates that the abnormality diagnosis is abnormal, the control circuit 33 switches to an abnormal stop mode to maintain the operation of the motor 20 in a stopped state.

[0110] When step S118 is completed, control circuit 33 moves to step S120.

[0111] In step S120, the control circuit 33 notifies the host device of information related to the abnormality diagnosis.

[0112] Information related to abnormal diagnosis includes, for example, information indicating the diagnostic result, information indicating whether the diagnostic conditions are met, and information about the signals of the diagnostic object. The host device is, for example, a control device such as the air conditioner 100 described later, that controls the overall operation of the device or system driven by the electric motor 20. Thus, the host device can notify the user or administrator of the device or system driven by the electric motor 20 of information related to abnormal diagnosis through a given notification unit such as an indicator, display device, or sound output device.

[0113] When step S120 is completed, the series of actions of the power conversion system 1 related to the abnormal diagnosis of the active noise canceller 60 ends.

[0114] In this example, the control circuit 67 performs anomaly diagnosis of the active noise canceller 60 based on the detection signal from the noise detection unit 50 when the inverter circuit 32 switches on without the rotation of the motor 20. Therefore, compared to the case where the inverter circuit 32 switches on with the normal rotation of the motor 20, the noise level of common-mode noise caused by the switching operation of the inverter circuit 32 can be reduced. Thus, even when anomaly diagnosis of the active noise canceller 60 is performed under abnormal conditions, the impact of common-mode noise on other devices connected to the power conversion system 1 can be suppressed.

[0115] Furthermore, in this example, the power conversion system 1 can complete the detection of diagnostic physical quantities, the determination of whether diagnostic conditions related to the diagnostic physical quantities are met, and the processing of abnormal diagnoses (i.e., the processing of steps S108, S110, and S112) all on the active noise canceller 60 side. Therefore, the control circuit 33 of the power conversion device 30 only needs to consider the conditions for determining the subsequent operating mode in conjunction with the diagnostic results, thus increasing the design freedom of the power conversion system 1. For example, this is because even if there are multiple specifications of the active noise canceller 60, the type of content output as the diagnostic result is common, so the control circuit 33 of the power conversion device 30 does not need to consider the specifications of the active noise canceller 60.

[0116] Furthermore, in this example, the control circuit 33 of the power conversion device 30 may not send a signal indicating that the operating mode has changed to the diagnostic mode to the control circuit 67 of the active noise canceller 60. Instead, it may wait for the diagnostic results of the abnormality diagnosis sent from the control circuit 67 in the diagnostic mode. In this case, steps S104 and S106 are omitted. The control circuit 67 of the active noise canceller 60 may recognize the change of the power conversion device 30 to the diagnostic mode on its own, without relying on the notification from the control circuit 33 of the power conversion device 30, or it may not recognize it on its own and always send the diagnostic results. The control circuit 33 of the power conversion device 30 recognizes the diagnostic mode and adopts the diagnostic results in the diagnostic mode.

[0117] [Example 2 of the operation of a power conversion system] Next, refer to Figure 3 The second example of the operation of the power conversion system 1 related to the abnormal diagnosis of the active noise canceller 60 will be described.

[0118] In this example, with the above Figure 2 The explanation focuses on the different content of the first example, and sometimes omits the explanation of the content that is the same as or corresponds to the first example above.

[0119] Since steps S202 to S210 are the same as steps S102 to S110 in the first example above, the explanation is omitted.

[0120] When the processing of step S210 is completed, the control circuit 67 of the active noise canceller 60 enters step S212.

[0121] In step S212, the control circuit 67 sends the determination result of whether the diagnostic conditions of step S210 are met to the control circuit 33 of the power conversion device 30 through a given communication line.

[0122] In step S214, the control circuit 33 of the power conversion device 30 receives the determination result sent in step S212.

[0123] When step S214 is completed, the control circuit 33 proceeds to step S216.

[0124] In step S216, the control circuit 33 performs anomaly diagnosis of the active noise canceller 60 based on the determination result of whether the diagnostic conditions received in step S216 are met or not, in the same way as step S112 of the first example above.

[0125] When step S216 is completed, the control circuit 33 proceeds to step S218.

[0126] Since steps S218 and S220 are the same as steps S118 and S120 in the first example above, the explanation is omitted.

[0127] When step S220 is completed, the series of actions of the power conversion system 1 related to the abnormal diagnosis of the active noise canceller 60 ends.

[0128] In this example, the control circuit 33 performs anomaly diagnosis of the active noise canceller 60 based on the detection signal from the noise detection unit 50 when the inverter circuit 32 switches on without the rotation of the motor 20. This achieves the same function and effect as in the first example described above.

[0129] Furthermore, in this example, the power conversion system 1 enables the control circuit 67 of the active noise canceller 60 to perform the detection of diagnostic physical quantities and the determination of whether diagnostic conditions related to those physical quantities are met (i.e., the processing in steps S208 and S210). Thus, the control circuit 67 can coordinate the processing from the detection of the diagnostic physical quantity to the determination of whether diagnostic conditions related to that physical quantity are met. Additionally, since the abnormality diagnosis processing of the active noise canceller 60 is performed by the control circuit 33 of the power conversion device 30, the power conversion system 1 can simplify the structure of the control circuit 67.

[0130] Furthermore, in this example, the control circuit 33 of the power conversion device 30 may not send a signal indicating that the operating mode has changed to the diagnostic mode to the control circuit 67 of the active noise canceller 60, but instead wait for the determination result of whether the diagnostic conditions are met from the control circuit 67 in the diagnostic mode. In this case, the processing of steps S204 and S206 is omitted. The control circuit 67 of the active noise canceller 60 may recognize the change of the power conversion device 30 to the diagnostic mode on its own, without relying on the notification from the control circuit 33 of the power conversion device 30, or it may not recognize it on its own and always send the determination result. The control circuit 33 of the power conversion device 30 recognizes the diagnostic mode and adopts the determination result in the diagnostic mode.

[0131] [Example 3 of the operation of a power conversion system] Next, refer to Figure 4 The third example of the operation of the power conversion system 1 related to the abnormal diagnosis of the active noise canceller 60 will be described.

[0132] In this example, with the above Figure 2 The first case Figure 3 The explanation focuses on the different content in the second example, and sometimes omits the explanation of the content that is the same as or corresponds to the first and second examples mentioned above.

[0133] Since steps S302 to S308 are the same as steps S102 to S108 in the first example above, the explanation is omitted.

[0134] When the processing of step S308 is completed, the control circuit 67 of the active noise canceller 60 enters step S310.

[0135] In step S310, the control circuit 67 sends information representing the diagnostic physical quantity detected in step S308 to the control circuit 33 of the power conversion device 30 via a given communication line.

[0136] In step S312, the control circuit 33 of the power conversion device 30 receives information representing diagnostic physical quantities sent in step S310.

[0137] In step S314, the control circuit 33 of the power conversion device 30, based on the information representing the diagnostic physical quantity received in step S312, determines whether the diagnostic conditions related to the diagnostic physical quantity are met or not in the same way as in step S110 of the first example described above.

[0138] When step S314 is completed, the control circuit 33 proceeds to step S316.

[0139] In step S316, the control circuit 33 performs anomaly diagnosis of the active noise canceller 60 based on the result of the determination of whether the diagnostic conditions related to the diagnostic physical quantity are met in step S314, using the same method as step S112 in the first example described above.

[0140] When step S316 is completed, the control circuit 33 proceeds to step S318.

[0141] Since steps S318 and S320 are the same as steps S118 and S120 in the first example above, the explanation is omitted.

[0142] When step S320 is completed, the series of actions of the power conversion system 1 related to the abnormal diagnosis of the active noise canceller 60 ends.

[0143] In this example, similar to the second example above, the control circuit 33 performs anomaly diagnosis of the active noise canceller 60 based on the detection signal from the noise detection unit 50 when the inverter circuit 32 switches on without the rotation of the motor 20. This achieves the same function and effect as the first and second examples above.

[0144] Furthermore, in this example, the power conversion system 1 enables the control circuit 33 of the power conversion device 30 to determine whether diagnostic conditions related to the diagnostic physical quantities are met and to perform abnormal diagnosis processing (i.e., the processing of steps S314 and S316). Therefore, the structure of the control circuit 67 of the active noise canceller 60 can be simplified. In addition, the control circuit 33 can, for example, use a microcomputer to set more advanced diagnostic conditions.

[0145] Furthermore, the control circuit 33 of the power conversion device 30 may not send a signal indicating that the operating mode has changed to the diagnostic mode to the control circuit 67 of the active noise canceller 60. Instead, it may wait in the diagnostic mode for information indicating diagnostic physical quantities to be sent from the control circuit 67. In this case, steps S304 and S306 are omitted. The control circuit 67 of the active noise canceller 60 may recognize the transition of the power conversion device 30 to the diagnostic mode independently, without relying on the notification from the control circuit 33 of the power conversion device 30. Alternatively, it may continuously send information indicating diagnostic physical quantities without self-recognition. The control circuit 33 of the power conversion device 30 recognizes the diagnostic mode and uses the information in the diagnostic mode.

[0146] Other examples of power conversion systems Next, other examples of power conversion system 1 will be described.

[0147] The structure or operation of the power conversion system 1 described above can be appropriately modified or altered. Hereinafter, examples of modifications or alterations to the structure or operation of the power conversion system 1 according to the above embodiments will be referred to as "modification examples" for convenience.

[0148] For example, in the power conversion system 1 of the above embodiment, the control circuit 67 can also cause the active noise canceller 60 to operate differently when the power conversion device 30 is in diagnostic mode compared to other operating modes accompanying the rotation of the motor 20. For example, when the power conversion device 30 is in diagnostic mode, the control circuit 67 controls the amplifier circuit 62 such that the amplification level (magnification ratio) of at least one of the amplifier circuit 62 and the compensation circuit 63 is greater than in other operating modes accompanying the rotation of the motor 20. This can suppress false diagnoses when the common-mode noise level is relatively low due to the diagnostic mode, thus improving diagnostic accuracy.

[0149] Furthermore, in the power conversion system 1 and its modifications described above, the AC power supply 10 can also replace the three-phase AC to supply single-phase AC to the power conversion system 1.

[0150] In addition, in the power conversion system 1 and its variations described above, the power conversion circuit 30C may also have a DC link provided between the rectifier circuit 31 and the inverter circuit 32, and a smoothing circuit including a smoothing capacitor or a smoothing inductor.

[0151] Furthermore, in the power conversion system 1 and its modifications described above, the function of the control circuit 33 can also be implemented by multiple circuits. For example, the function of performing abnormality diagnosis for the active noise canceller 60 in the control circuit 33 can also be implemented by a diagnostic circuit different from the control circuit 33. In addition, part or all of the function of the control circuit 33 can be transferred to the outside of the power conversion device 30.

[0152] Furthermore, in the power conversion system 1 and its variations described above, the noise filter 40 may also be omitted.

[0153] In addition, in the power conversion system 1 and its modifications described above, the noise detection unit 50 may also use known methods (for example, see Japanese Patent No. 5528543 and Japanese Patent No. 7309067) to detect common-mode noise via a capacitor.

[0154] Furthermore, in the power conversion system 1 and its modifications described above, the noise detection unit 50 may also include the function of a filter circuit 61. In this case, the filter circuit 61 is omitted, and the filter circuit in the noise detection unit 50 outputs a detection signal after removing specific frequency components. This detection signal is then input to the operational amplifier or the like in the amplifier circuit 62.

[0155] Furthermore, in the power conversion system 1 and its variations described above, the filter circuit 61 may also be omitted.

[0156] Furthermore, in the power conversion system 1 and its modifications described above, the function of the amplifier circuit 62 can also be implemented by a microcontroller. In this case, the amplifier circuit 62 is omitted, and the microcontroller is input with a detection signal from the noise detection unit 50 or a signal output from the filter circuit 61. Then, based on the input signal, the microcontroller generates a signal representing the waveform of the compensation current or compensation voltage and inputs it to the compensation circuit 63. For example, instead of the amplifier circuit 62, the microcontroller, either included in or separate from the control circuit 67, outputs a signal representing the waveform of the compensation current or compensation voltage based on the detection signal from the noise detection unit 50 or the signal output from the filter circuit 61.

[0157] Furthermore, in the power conversion system 1 and its modifications described above, the function of the amplifier circuit 62 can also be transferred to the outside of the active noise canceller 60. In this case, the amplifier circuit 62 is omitted. For example, the detection signal from the noise detection unit 50 or the signal output from the filter circuit 61 is input to the control circuit 33 of the power conversion device 30 via a given communication line. Then, the control circuit 33 generates a signal representing the waveform of the compensation current or compensation voltage based on the input signal, and sends it to the active noise canceller 60 via the given communication line. The signal representing the waveform of the compensation current or compensation voltage is input to the compensation circuit 63.

[0158] Furthermore, in the power conversion system 1 and its modifications described above, the diodes D1 and D2 of the compensation circuit 63 may be omitted.

[0159] Furthermore, in the power conversion system 1 and its variations described above, either the amplifier circuit 62 or the compensation circuit 63 may be omitted.

[0160] In addition, in the power conversion system 1 and its variations described above, the output unit 64 may also have a resistor connected in series with the output capacitor Co.

[0161] Furthermore, in the power conversion system 1 and its modifications described above, 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 the compensation circuit 63 may be directly connected to the ground GL.

[0162] In addition, in the power conversion system 1 and its variations described above, the output unit 64 may also be configured to output compensation current or compensation voltage to the power line PL12.

[0163] Furthermore, in the power conversion system 1 and its modifications described above, the output unit 64 can also employ a known method (for example, refer to Japanese Patent No. 5528543 or Japanese Patent No. 7309067) to output compensation current or compensation voltage to the power line PL1 via magnetic coupling. In this case, the output unit 64 includes a primary coil magnetically coupled to the wire harness corresponding to the power line PL1 or ground GL, and a toroidal core to which the primary coil is wound, with the wire harness corresponding to the power line PL1 or ground GL inserted into the toroidal core. Additionally, a coil wound around the toroidal core may also be formed in the wire harness corresponding to the power line PL1 or ground GL.

[0164] Furthermore, in the power conversion system 1 and its modifications described above, the active noise canceller 60 may also be configured to allow the compensation current Io to flow between the DC link of the power conversion circuit 30C and ground GL. For example, as described above, when the drive power supply 70 utilizes the DC voltage of the DC link of the power conversion circuit 30C, the compensation current Io flows between the DC link and ground GL through this power path. In this case, the noise detection unit 50 may be configured to detect the common-mode noise of the power line PL1, or it may be configured to detect the common-mode noise of the DC link of the power conversion circuit 30C.

[0165] Furthermore, in the power conversion system 1 and its modifications described above, the active noise canceller 60 can also be configured to allow the compensation current Io to flow between the power line PL2 between the power conversion device 30 and the motor 20 and the ground GL. For example, one end of the coupling capacitor 66 is connected to the power lines of each phase of the power line PL2, namely the U-phase, V-phase, and W-phase. In this case, the noise detection unit 50 can be configured to detect the common-mode noise of the power line PL1 or the common-mode noise of the power line PL2.

[0166] In addition, in the power conversion system 1 and its modifications described above, the drive power supply 70 may also be included in the active noise canceller 60.

[0167] In addition, in the power conversion system 1 described above, besides the noise detection unit 50, other noise detection units may be provided for diagnosing anomalies in the active noise canceller 60. In this case, the other noise detection units, like the noise detection unit 50, detect the common-mode noise of the power line PL1 or power line PL2 or ground GL, and perform anomaly diagnosis of the active noise canceller 60 based on the detection signal.

[0168] Furthermore, in the power conversion system 1 described above, some or all of the functions for diagnosing abnormalities in the active noise canceller 60 may be located outside the power conversion device 30 or the active noise canceller 60. In this case, some or all of the functions for diagnosing abnormalities in the active noise canceller 60 may be located outside the device or system on which the power conversion system 1 is assembled, i.e., the device or system driven by the motor 20. For example, some or all of the functions for diagnosing abnormalities in the active noise canceller 60 may be performed by an external diagnostic device located outside the power conversion system 1 and capable of communicating with the power conversion system 1.

[0169] [Application Examples of Power Conversion Systems] Next, refer to Figure 5An application example of the power conversion system 1 according to this embodiment will be described. Specifically, an air conditioner 100 equipped with the power conversion system 1 according to this embodiment will be described.

[0170] Figure 5 This is a diagram showing an example of the refrigerant circuit of an air conditioner 100.

[0171] like Figure 5 As shown, 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 consisting of the outdoor unit 110, the indoor unit 120, and the refrigerant paths 130 and 140 to adjust the temperature or humidity of the room where the indoor unit 120 is located.

[0172] The outdoor unit 110 is installed outdoors in a building where temperature and other parameters 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 refrigerant from either of the refrigerant paths 130 and 140 and discharges refrigerant to either of the other paths.

[0173] Indoor unit 120 is installed inside the building where temperature and other parameters are to be adjusted. Indoor unit 120 is connected to the other end of refrigerant paths 130 and 140, respectively, and draws in refrigerant from either refrigerant path 130 or 140 and discharges refrigerant to either refrigerant path 140.

[0174] The refrigerant paths 130 and 140 are, for example, formed by pipes, connecting 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.

[0175] The outdoor unit 110 includes refrigerant paths L1 to L6, oil paths L7 and L8, a four-way switching valve 111, a liquid receiver 112, a compressor 113, an oil separator 114, an outdoor heat exchanger 115, an outdoor expansion valve 116, and a fan 117.

[0176] The refrigerant paths L1 to L6 are configured as pipelines, for example.

[0177] The refrigerant path L1 is connected between one end of the refrigerant path 130 outside the outdoor unit 110 and the four-way switching valve 111.

[0178] Refrigerant path L2 connects the four-way switching valve 111 to the inlet of compressor 113. Refrigerant path L2 includes refrigerant paths L21 and L22.

[0179] Refrigerant path L21 connects the four-way switching valve 111 and the receiver 112. Refrigerant path L22 connects the receiver 112 and the inlet of the compressor 113.

[0180] Refrigerant path L3 connects the four-way switching valve 111 to the outlet of compressor 113. Refrigerant path L3 includes refrigerant paths L31 and L32.

[0181] Refrigerant path L31 connects the outlet of compressor 113 to oil separator 114. Refrigerant path L32 connects the four-way switching valve 111 to oil separator 114.

[0182] The refrigerant path L4 is connected between the four-way switching valve 111 and the outdoor heat exchanger 115.

[0183] The refrigerant path L5 is connected between the outdoor heat exchanger 115 and the outdoor expansion valve 116.

[0184] The refrigerant path L6 is connected between one end of the refrigerant path 140 outside the outdoor unit 110 and the outdoor expansion valve 116.

[0185] The oil path L7 is configured as a pipeline for allowing the oil separated by the oil separator 114 to flow into the refrigerant path L22 and return to the compressor 113 via the refrigerant path L22.

[0186] Furthermore, the oil passing through oil path L7 may sometimes contain a liquid refrigerant (hereinafter referred to as "liquid refrigerant"). That is, in oil path L7, not only oil but also liquid refrigerant flows.

[0187] The oil path L8 is configured, for example, as a pipeline, for allowing oil containing liquid refrigerant separated from the receiver 112 to flow into the refrigerant path L22 and return to the compressor 113 via the refrigerant path L22.

[0188] The four-way switching valve 111 reverses the flow of refrigerant circulation when the air conditioner 100 is in cooling or heating operation.

[0189] When the air conditioner 100 is in cooling operation, the four-way switching valve 111 is connected. Figure 5 The solid lines in the diagram represent the paths. Specifically, during the cooling operation of the air conditioner 100, the four-way switching valve 111 connects the refrigerant path L1 with the refrigerant path L2, and the refrigerant path L3 with the refrigerant path L4.

[0190] On the other hand, when the air conditioner 100 is in heating mode, the four-way switching valve 111 is connected... Figure 5 The path is indicated by the dotted line. Specifically, when the air conditioner 100 is in heating operation, the four-way switching valve 111 connects the refrigerant path L4 with the refrigerant path L2, and the refrigerant path L1 with the refrigerant path L3.

[0191] The receiver 112 separates the liquid refrigerant contained in the refrigerant drawn in from the refrigerant path L21, and sprays the refrigerant, after part or all of the liquid refrigerant has been removed, into the refrigerant path L22. The liquid refrigerant separated in the receiver 112 contains oil. The receiver 112 is provided with an oil drain port connected to the oil path L8. The oil containing the separated refrigerant flows out through the oil drain port into the oil path L8, and then returns to the compressor 113 through the oil path L8 and the refrigerant path L22.

[0192] The compressor 113 is driven by the electric motor 20. It draws in refrigerant from the refrigerant path L22, compresses it to high pressure, and sprays it into the refrigerant path L31. Thus, the power conversion system 1 can control the operation of the compressor 113 by driving the electric motor 20.

[0193] When the air conditioner 100 is in cooling operation, the high-temperature and high-pressure refrigerant compressed by the compressor 113 flows into the outdoor heat exchanger 115 through the refrigerant path L3 and the refrigerant path L4.

[0194] On the other hand, when the air conditioner 100 is in heating mode, the high-temperature and high-pressure refrigerant compressed by the compressor 113 flows out through refrigerant path L3 and refrigerant path L1 to the refrigerant path 130 outside the outdoor unit 110. Then, the high-temperature and high-pressure refrigerant flows into the indoor unit 120 through refrigerant path 130.

[0195] Oil separator 114 separates oil from the refrigerant flowing in from refrigerant path L31, and the refrigerant after some or all of the oil has been separated and removed flows out to refrigerant path L32. In addition, oil separator 114 is provided with an oil drain port connected to oil path L7. The oil separated from the refrigerant flows out through the oil drain port to oil path L7, and then returns to compressor 113 through oil path L7 and refrigerant path L22.

[0196] The outdoor heat exchanger 115 exchanges heat between outside air and refrigerant flowing inside. Specifically, a fan 117 is arranged side by side with the outdoor heat exchanger 115, and the outdoor heat exchanger 115 exchanges heat between outside air blown by the fan 117 and refrigerant flowing inside.

[0197] When the air conditioner 100 is in cooling operation, the outdoor heat exchanger 115 dissipates heat from the high-temperature and high-pressure refrigerant that flows in from the refrigerant path L4 and is compressed by the compressor 113 to the outside air, so that the condensed / liquefied refrigerant (liquid refrigerant) flows out to the refrigerant path L5.

[0198] In addition, when the air conditioner 100 is in heating operation, 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, so that the evaporated refrigerant flows out to the refrigerant path L4.

[0199] When the air conditioner 100 is in heating operation, the outdoor expansion valve 116 is closed to a given opening, reducing the pressure of the refrigerant (liquid refrigerant) flowing in from the refrigerant path L6 to a given pressure. Conversely, when the air conditioner 100 is in cooling operation, the outdoor expansion valve 116 is set to a fully open state, allowing refrigerant (liquid refrigerant) to flow from the refrigerant path L5 to the refrigerant path L6. The outdoor expansion valve 116 is, for example, a solenoid valve.

[0200] The indoor unit 120 includes an indoor expansion valve 121, an indoor heat exchanger 122, and a fan 123.

[0201] During cooling operation of the air conditioner 100, the indoor expansion valve 121 is closed to a given opening, reducing the pressure of the subcooled liquid refrigerant flowing in from the refrigerant path 140 to a given pressure. Conversely, during heating operation of the air conditioner 100, the indoor expansion valve 121 is fully open, allowing the refrigerant (liquid refrigerant) flowing from the indoor heat exchanger 122 to pass through the refrigerant path 140. The indoor expansion valve 121 is, for example, a solenoid valve.

[0202] The indoor heat exchanger 122 facilitates heat exchange between indoor air and the refrigerant passing through it. Specifically, through the action of the fan 123 mounted on the indoor unit 120, indoor air passes around the indoor heat exchanger 122, promoting heat exchange with the refrigerant inside the indoor heat exchanger 122. Furthermore, through the action of the fan 123, the indoor air that has undergone heat exchange with the refrigerant inside the indoor heat exchanger 122 is exhausted to the outside of the indoor unit 120, thereby achieving indoor cooling or heating.

[0203] When the air conditioner 100 is in cooling operation, the indoor heat exchanger 122 causes the low-temperature, low-pressure liquid refrigerant, which has been depressurized by the indoor expansion valve 121, to absorb heat from the indoor air, thereby lowering the temperature of the indoor air.

[0204] On the other hand, when the air conditioner 100 is in heating mode, the indoor heat exchanger 122 dissipates the high-temperature and high-pressure refrigerant flowing from the outdoor unit 110 through the refrigerant path 130 to the indoor air, thereby increasing the temperature of the indoor air.

[0205] In this example, the power conversion system 1 of this embodiment is applied to the air conditioner 100 in the form of being mounted on the air conditioner 100.

[0206] Furthermore, the power conversion system 1 described in this embodiment can also be applied to refrigeration devices different from the air conditioner 100.

[0207] [effect] Next, the functions of the power conversion system and the air conditioner involved in this embodiment will be explained.

[0208] In the first embodiment of this invention, the power conversion system includes a power conversion device, a detection unit, a noise suppression device, and a first circuit. The power conversion system is, for example, the power conversion system 1 described above. The power conversion device is, for example, the power conversion device 30 described above. The detection unit is, for example, the noise detection unit 50 described above. The noise suppression device is, for example, the active noise canceller 60 described above. The first circuit is either the control circuit 67 or the control circuit 33 described above. Specifically, the power conversion device is connected to an AC power source and a motor via power lines, and drives the motor by switching a switching element to supply power from the AC power source. The AC power source is, for example, the AC power source 10 described above. The motor is, for example, the motor 20 described above. The power lines are, for example, power lines PL1 and PL2 described above. Furthermore, the detection unit detects common-mode noise flowing in the path containing the power lines accompanying the switching action of the switching element and outputs a detection signal. Additionally, the noise suppression device, based on the detection signal output from the detection unit, outputs a compensation current or compensation voltage to the path to suppress the common-mode noise. Furthermore, the first circuit performs diagnostics related to the common-mode noise state based on a signal associated with the common-mode noise state during the switching operation of the power conversion device without the rotation of the motor. The signal associated with the common-mode noise state is, for example, the detection signal of the noise detection unit 50 or a signal derived from that detection signal. Alternatively, the signal associated with the common-mode noise state may also be, for example, the detection signal of a noise detection unit separately from the noise detection unit 50 or a signal derived from that detection signal.

[0209] Therefore, the power conversion system can suppress the common-mode noise level when performing diagnostics related to anomalies in the noise suppression device.

[0210] Furthermore, in the second embodiment of this invention, based on the first embodiment described above, the signal related to the state of the common-mode noise can also be a detection signal output from the detection unit or a signal originating from the detection signal.

[0211] Therefore, the power conversion system 1 can use the detection signal of the detection unit or the signal derived from the detection signal to perform diagnosis related to the abnormality of the noise suppression device.

[0212] Furthermore, in the third embodiment of this invention, based on the first or second embodiment described above, the noise suppression device may also include the first circuit. Then, the first circuit can use a signal related to the state of the common-mode noise during the switching operation of the power conversion device without the rotation of the motor to determine whether the conditions related to the diagnosis are met, and perform the diagnosis based on the determination result.

[0213] Therefore, the power conversion system can complete the diagnostic processing related to anomalies of the noise suppression device within the noise suppression device itself. Thus, for example, even when there are multiple specifications of the noise suppression device, the power conversion system only needs to determine the action associated with the diagnostic results, without considering the differences in specifications. Therefore, the design freedom of the power conversion system 1 can be increased.

[0214] Furthermore, in the fourth embodiment of this invention, based on the first or second embodiment described above, the noise suppression device may also include a second circuit. Additionally, the power conversion device may also include the first circuit. Furthermore, the second circuit can use a signal related to the state of the common-mode noise during the switching operation of the power conversion device without the rotation of the motor to determine whether the conditions related to the diagnosis are met. Then, the first circuit can perform the diagnosis based on the determination result of the second circuit.

[0215] Therefore, the power conversion system enables the power conversion device to perform diagnoses related to anomalies in the noise suppression device. Thus, for example, compared to performing diagnoses related to anomalies in the noise suppression device itself, the structure of the noise suppression device can be simplified.

[0216] Furthermore, in the fifth embodiment of this invention, based on the first or second embodiment described above, the power conversion device may also include the first circuit. Then, the first circuit can use a signal related to the state of the common-mode noise during the switching operation performed by the power conversion device without the rotation of the motor to determine whether the conditions related to the diagnosis are met, and perform the diagnosis based on the determination result.

[0217] Therefore, the power conversion system enables the power conversion device to determine whether diagnostic conditions are met and to perform diagnoses related to anomalies in the noise suppression device based on the determination results. Thus, for example, compared to determining whether diagnostic conditions are met and performing diagnoses related to anomalies in the noise suppression device, the structure of the noise suppression device can be simplified.

[0218] In addition, in the sixth embodiment of this invention, based on any one of the first to fifth embodiments described above, the power conversion system may also include a third circuit that controls the power conversion device for the purpose of the diagnosis and causes it to perform the switching operation without the rotation of the motor.

[0219] Therefore, in order to perform diagnostics related to anomalies in the noise suppression device, the power conversion system can enable the power conversion device to perform switching operations without the motor's rotation.

[0220] In addition, in the seventh embodiment of this invention, based on any one of the first to sixth embodiments described above, the power conversion device may also perform the switching operation without the rotation of the motor by applying a DC voltage to the motor.

[0221] Therefore, the power conversion system 1 can switch the power conversion device on and off without rotating the motor.

[0222] Furthermore, in the eighth embodiment of this invention, based on any one of the first to sixth embodiments described above, the motor can also be driven by three-phase AC. Then, the power conversion device can perform the switching operation without accompanying the rotation of the motor by applying AC voltage to two of the three phases of the motor.

[0223] Therefore, the power conversion system 1 can switch the power conversion device on and off without rotating the motor.

[0224] Furthermore, in the ninth embodiment of this invention, based on the first or second embodiment described above, an amplification circuit and a compensation circuit may also be included. The amplification circuit amplifies the detection signal output from the detection unit or the signal output from the filter circuit through which the detection signal passes. The compensation circuit outputs the compensation current or the compensation voltage based on the signal output from the amplification circuit. Then, when at least one of the amplification circuit and the compensation circuit performs a switching operation without the rotation of the motor via the power conversion device, the amplification level can be set to be greater than when the switching operation is performed with the rotation of the motor via the power conversion device.

[0225] Therefore, the power conversion system 1 can improve the accuracy of diagnosis related to anomalies in the noise suppression device.

[0226] Furthermore, in the tenth embodiment of this invention, based on any one of the first to ninth embodiments described above, the noise suppression device may also include a filter circuit, an amplifier circuit, and a compensation circuit. The filter circuit is, for example, the filter circuit 61 described above. The amplifier circuit is, for example, the amplifier circuit 62 described above. The compensation circuit is, for example, the compensation circuit 63 described above. Specifically, the filter circuit allows the detection signal output from the detection unit to pass through and removes specific frequency components. Additionally, the amplifier circuit amplifies the signal output from the filter circuit. Furthermore, the compensation circuit outputs the compensation current or the compensation voltage based on the signal output from the amplifier circuit.

[0227] Therefore, the noise suppression device is able to suppress common-mode noise in the aforementioned path, which includes power lines.

[0228] Furthermore, in the 11th embodiment of this invention, based on the second embodiment described above, the noise suppression device may also include a filter circuit, an amplifier circuit, and a compensation circuit. Specifically, the filter circuit allows the detection signal output from the detection unit to pass through and removes specific frequency components. Additionally, the amplifier circuit amplifies the signal output from the filter circuit. Then, the compensation circuit outputs the compensation current or the compensation voltage based on the signal output from the amplifier circuit. The signal originating from the detection signal output from the detection unit may be at least one of the signal output from the filter circuit, the signal output from the amplifier circuit, and the signal representing the compensation current or the compensation voltage output from the compensation circuit.

[0229] Therefore, the power conversion system can use the detection signal from the detection unit to perform diagnoses related to anomalies in the noise suppression device.

[0230] Furthermore, in the 12th embodiment of this invention, based on any one of the 1st to 11th embodiments described above, the switching element may be a wide-bandgap semiconductor.

[0231] Therefore, the power conversion system can suppress the common-mode noise level associated with the switching action of wide-bandgap semiconductors when performing diagnostics related to anomalies of the noise suppression device.

[0232] Furthermore, in the 13th embodiment of this invention, the air conditioner may also include a power conversion system of any one of the 1st to 12th embodiments described above. The air conditioner is, for example, the air conditioner 100 described above.

[0233] Therefore, when applied to air conditioners, power conversion systems can suppress common-mode noise during the operation of the motors driving the air conditioners.

[0234] The embodiments have been described above, but it should be understood that various changes in manner or details are possible without departing from the spirit and scope of the claims.

[0235] Finally, this application claims priority based on Japanese Patent Application No. 2024-058034, filed on March 29, 2024, the entire contents of which are incorporated herein by reference.

[0236] Symbol Explanation 1: Power conversion system 10: AC power supply 20: Electric motor 30: Power conversion device 31: Rectifier circuit 32: Inverter circuit 33: Control Circuit 40: Noise Filter 50: Noise Detection Unit 60: Active noise canceller 61: Filter circuit 62: Amplifier Circuit 63: Compensation Circuit 64: Output Section 67: Control Circuit 70: Drive power supply 100: Air conditioner PL1: Power line PL2: Power Line PL11: Power Line PL12: Power line PL13: Power line.

Claims

1. A power conversion system, comprising: The power conversion device (30) is connected to the AC power source (10) and the motor (20) via the power line (PL1) and drives the motor (20) using the power supplied from the AC power source (10) by switching the switching element. The detection unit (50) detects common-mode noise flowing in the path containing the power line (PL1) accompanying the switching action of the switching element, and outputs a detection signal. A noise suppression device (60) outputs a compensation current or compensation voltage to the path based on the detection signal output from the detection unit (50) to suppress the common-mode noise; as well as The first circuit (33, 67) performs a diagnosis of anomalies related to the noise suppression device (60) based on a signal related to the state of the common-mode noise when the switching action is performed by the power conversion device (30) without the rotation of the motor (20).

2. The power conversion system according to claim 1, wherein, The signal associated with the state of the common-mode noise is a detection signal output from the detection unit (50) or a signal originating from the detection signal.

3. The power conversion system according to claim 1 or 2, wherein, The noise suppression device (60) includes the first circuit (67). The first circuit (67) uses a signal related to the state of the common-mode noise when the switching action is performed by the power conversion device (30) without the rotation of the motor (20) to determine whether the conditions related to the diagnosis are met, and performs the diagnosis based on the determination result.

4. The power conversion system according to claim 1 or 2, wherein, The noise suppression device (60) includes a second circuit (67). The power conversion device (30) includes the first circuit (33). The second circuit (67) uses a signal related to the common-mode noise state during the switching action of the power conversion device (30) without the rotation of the motor (20) to determine whether the conditions related to the diagnosis are met. The first circuit (33) performs the diagnosis based on the determination result of the second circuit (67).

5. The power conversion system according to claim 1 or 2, wherein, The power conversion device (30) includes the first circuit (33). The first circuit (33) uses a signal related to the state of the common-mode noise when the switching action is performed by the power conversion device (30) without the rotation of the motor (20) to determine whether the conditions related to the diagnosis are met, and performs the diagnosis based on the determination result.

6. The power conversion system according to any one of claims 1 to 5, wherein, The power conversion system includes a third circuit (33) that controls the power conversion device (30) for the purpose of the diagnosis, performing the switching action without the rotation of the motor (20).

7. The power conversion system according to any one of claims 1 to 6, wherein, The power conversion device (30) performs the switching action without the rotation of the motor (20) by applying a DC voltage to the motor (20).

8. The power conversion system according to any one of claims 1 to 6, wherein, The motor (20) is driven by a 3-phase AC motor. The power conversion device (30) performs the switching action without the rotation of the motor (20) by applying AC voltage to two of the three phases of the motor (20).

9. The power conversion system according to claim 1 or 2, wherein, The power conversion system includes: An amplifier circuit (62) amplifies the detection signal output from the detection unit (50) or the signal output from the filter circuit (61) through which the detection signal passes. as well as The compensation circuit (63) outputs the compensation current or the compensation voltage based on the signal output from the amplifier circuit (62). When the switching operation is performed by the power conversion device (30) without the rotation of the motor (20), the amplification circuit (62) or the compensation circuit (63) increases the amplification degree compared to the case where the switching operation is performed by the power conversion device (30) with the rotation of the motor (20).

10. The power conversion system according to any one of claims 1 to 9, wherein, The noise suppression device (60) comprises: A filter circuit (61) allows the detection signal output from the detection unit (50) to pass through and removes specific frequency components; An amplifier circuit (62) amplifies the signal output from the filter circuit (61); as well as The compensation circuit (63) outputs the compensation current or the compensation voltage based on the signal output from the amplifier circuit (62).

11. The power conversion system according to claim 2, wherein, The noise suppression device (60) comprises: A filter circuit (61) allows the detection signal output from the detection unit (50) to pass through and removes specific frequency components; An amplifier circuit (62) amplifies the signal output from the filter circuit (61); as well as The compensation circuit (63) outputs the compensation current or the compensation voltage based on the signal output from the amplifier circuit (62). The signal originating from the detection signal output from the detection unit (50) is the signal output from the filter circuit (61), the signal output from the amplifier circuit (62), or the signal representing the compensation current or the compensation voltage output from the compensation circuit (63).

12. The power conversion system according to any one of claims 1 to 11, wherein, The switching element uses a wide-bandgap semiconductor.

13. An air conditioner comprising the power conversion system (1) of any one of claims 1 to 12.

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