Power conversion system, and air conditioner

Abstract

To provide a technique capable of suppressing a common-mode noise level when performing diagnosis relating to an abnormality of a noise suppression device.SOLUTION: A power conversion system 1 comprises: a power conversion device 30 which drives a motor 20 with power supplied from an AC power source 10 by performing a switching operation on a switching element; noise detection means 50 which detects a common-mode noise flowing in a path including power lines PL1 and PL2 with the switching operation of the switching element and outputs a detection signal; an active noise canceller 60 which outputs a compensation current or a compensation voltage to the path on the basis of the detection signal outputted from the noise detection means and suppresses the common-mode noise; and a control circuit 67 which performs diagnosis relating to an abnormality of the active noise canceller 60 on the basis of a signal relating to a state of the common-mode noise when performing a switching operation which is not accompanied with a rotating operation of the motor 20 by the power conversion device 30.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] Conventionally, there is known a technique for suppressing common mode noise in a power conversion system including a power conversion device that drives a motor by the switching operation of a switching element using power supplied from an AC power source through a power line (see, for example, Patent Document 1).

[0003] Patent Document 1 discloses an active noise suppression technology that detects common mode noise and reduces the common mode noise by outputting a compensating current or voltage for the detected common mode noise to a path through which the common mode noise flows. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 3044650 Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, there are cases where a diagnosis of an abnormality in a noise suppression device is performed, for example, by determining whether common mode noise is being appropriately suppressed.

[0006] However, if a diagnosis of an abnormality in a noise suppression device is performed during normal operation of a load device such as a motor, the load device may continue to operate normally even if the noise suppression device is malfunctioning or showing signs of malfunction, which may result in the common-mode noise not being properly suppressed and potentially leaking to other devices connected to the power conversion system.

[0007] An object of the present disclosure is to provide a technique capable of suppressing the common-mode noise level when diagnosing an abnormality in a noise suppression device. [Means for solving the problem]

[0008] In a first aspect of the present disclosure, a power conversion device connected to an AC power supply and a motor via power lines, and configured to drive the motor with power supplied from the AC power supply by switching a switching element; a detection means for detecting common mode noise flowing in a path including the power line due to a switching operation of the switching element, and outputting a detection signal; a noise suppression device that outputs a compensation current or a compensation voltage to the path based on the detection signal output from the detection means, thereby suppressing the common mode noise; a first circuit that diagnoses an abnormality in the noise suppression device based on a signal related to the state of the common mode noise when the power conversion device performs the switching operation without rotating the motor, A power conversion system is provided.

[0009] According to this aspect, the power conversion system can suppress the common mode noise level when diagnosing an abnormality in the noise suppression device.

[0010] In addition, in a second aspect of the present disclosure, based on the first aspect described above, The signal relating to the state of the common mode noise may be a detection signal output from the detection means, or a signal derived from the detection signal.

[0011] In addition, in a third aspect of the present disclosure, based on the first or second aspect described above, the noise suppression device includes the first circuit; The first circuit may determine whether a condition for the diagnosis is met using a signal related to the state of the common mode noise when the power conversion device performs the switching operation without rotating the motor, and may perform the diagnosis based on the result of the determination.

[0012] Furthermore, in a fourth aspect of the present disclosure, based on the first or second aspect described above, the noise suppression device includes a second circuit; the power conversion device includes the first circuit; the second circuit determines whether a condition related to the diagnosis is met by using a signal related to a state of the common mode noise when the power conversion device performs the switching operation without rotating the motor; The first circuit may perform the diagnosis based on the determination result of the second circuit.

[0013] In addition, in a fifth aspect of the present disclosure, on the premise of any one of the first and second aspects described above, the power conversion device includes the first circuit; The first circuit may determine whether a condition for the diagnosis is met using a signal related to the state of the common mode noise when the power conversion device performs the switching operation without rotating the motor, and may perform the diagnosis based on the result of the determination.

[0014] 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 converter may further include a third circuit that controls the power conversion device for the diagnosis and causes the switching operation to be performed without causing the motor to rotate.

[0015] In addition, in a seventh aspect of the present disclosure, on the premise of any one of the first to sixth aspects described above, The power conversion device may perform the switching operation without rotating the motor, so as to apply a DC voltage to the motor.

[0016] In addition, in an eighth aspect of the present disclosure, on the premise of any one of the first to sixth aspects described above, The motor is driven by three-phase AC, The power conversion device may perform the switching operation without rotating the motor, so as to apply an AC voltage to two of three phases of the motor.

[0017] In addition, in a ninth aspect of the present disclosure, based on the second aspect described above, an amplifier circuit that amplifies the detection signal output from the detection means or the signal output from a filter circuit through which the detection signal passes; a compensation circuit that outputs the compensation current or the compensation voltage based on the signal output from the amplifier circuit, The amplifier circuit or the compensation circuit may increase the degree of amplification when the power conversion device performs the switching operation without rotating the motor compared to when the power conversion device performs the switching operation with rotating the motor.

[0018] In addition, in a tenth aspect of the present disclosure, on the premise of any one of the first to ninth aspects described above, The noise suppression device comprises: a filter circuit that passes the detection signal output from the detection means and removes specific frequency components; an amplifier circuit that amplifies the signal output from the filter circuit; The power supply may further include a compensation circuit that outputs the compensation current or the compensation voltage based on the signal output from the amplifier circuit.

[0019] In addition, in an eleventh aspect of the present disclosure, based on the second aspect described above, The noise suppression device comprises: a filter circuit that passes the detection signal output from the detection means and removes specific frequency components; an amplifier circuit that amplifies the signal output from the filter circuit; a compensation circuit that outputs the compensation current or the compensation voltage based on the signal output from the amplifier circuit, The signal derived from the detection signal output from the detection means may be 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.

[0020] In addition, in a twelfth aspect of the present disclosure, on the premise of any one of the first to eleventh aspects described above, The switching element may be made of a wide bandgap semiconductor.

[0021] In addition, a thirteenth aspect of the present disclosure is a power conversion system including any one of the first to twelfth aspects described above. An air conditioner is provided. [Effects of the Invention]

[0022] According to the above-described embodiment, it is possible to suppress the common mode noise level when diagnosing an abnormality in the noise suppression device. [Brief explanation of the drawings]

[0023] [Figure 1] FIG. 1 is a diagram illustrating an example of a power conversion system. [Figure 2] FIG. 3 is a sequence diagram showing a first example of the operation of the power conversion system. [Figure 3] FIG. 10 is a sequence diagram showing a second example of the operation of the power conversion system. [Figure 4] FIG. 10 is a sequence diagram showing a third example of the operation of the power conversion system. [Figure 5] FIG. 1 is a diagram illustrating an example of a refrigerant circuit of an air conditioner. DETAILED DESCRIPTION OF THE INVENTION

[0024] Hereinafter, an embodiment will be described with reference to the drawings.

[0025] [Power conversion system configuration] The configuration of a power conversion system 1 according to this embodiment will be described with reference to FIG.

[0026] FIG. 1 is a diagram illustrating an example of a power conversion system 1. As shown in FIG.

[0027] As shown in FIG. 1, a power conversion system 1 drives a motor 20 using power supplied from an AC power supply 10.

[0028] 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.

[0029] 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.

[0030] 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 .

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] The power conversion device 30 includes, for example, a rectifier circuit 31, an inverter circuit 32, and a control circuit 33.

[0036] 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 a DC link (also referred to as a "direct current link"). The rectifier circuit 31 is, for example, a three-phase full-wave rectifier circuit using diodes.

[0037] The inverter circuit 32 converts the direct current input from the DC link between the rectifier circuit 31 and itself into three-phase alternating current of a predetermined frequency and a predetermined voltage, specifically, U-phase, V-phase, and W-phase alternating current, and outputs the converted three-phase alternating current. The inverter circuit 32 includes, for example, switching elements, and converts the direct current into three-phase alternating current of a predetermined frequency and a predetermined voltage through the switching operation of the switching elements, and outputs the converted three-phase alternating current to the power line PL2.

[0038] 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.

[0039] The control circuit 33 performs control processing related to the power conversion device 30.

[0040] The control circuit 33 may also perform other processes related to the power conversion system 1.

[0041] 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).

[0042] 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.

[0043] 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.

[0044] The noise filter 40 is a passive noise suppression device that suppresses common mode noise.

[0045] 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.

[0046] The noise filter 40 includes a common mode choke coil 41 and a Y capacitor 42 .

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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 primary circuit including a coil 51 and a secondary circuit including a coil 52.

[0051] The coils 51 are provided for the R-phase, S-phase, and T-phase of the power line PL1, respectively.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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 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 control circuit 67.

[0056] 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 .

[0057] The amplifier circuit 62 amplifies the signal output from the filter circuit 61. The amplifier circuit 62 includes, for example, an operational amplifier. The signal output from the amplifier circuit 62 is input to the compensation circuit 63.

[0058] The power supply voltage of the operational amplifier is, for example, 2 / 3 or less of the DC link voltage (DC link voltage) Vdc 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 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] Diodes D1 and D2 are connected in antiparallel to the transistors Tr1 and Tr2, respectively, to protect them.

[0065] The output section 64 outputs the compensation current or compensation voltage output from the compensation circuit 63 to a path through which the common mode current flows. The output section 64 includes an output capacitor Co.

[0066] 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.

[0067] The power supply circuit 65 is connected to a drive power supply 70. The power supply circuit 65 includes capacitors C1 and C2.

[0068] 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.

[0069] Coupling capacitor 66 has one end connected to power line PL12 and the other end connected to the midpoint between capacitors C1 and C2.

[0070] The control circuit 67 performs control processing related to the active noise canceller 60 .

[0071] The control circuit 67 may also perform processing for diagnosing abnormalities in the active noise canceller 60.

[0072] The functions of the control circuit 67 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 67 is mainly configured with a microcomputer including a CPU, a memory device, an auxiliary storage device, an input / output interface, etc.

[0073] The functions of the control circuit 67 may be realized by a plurality of circuits. For example, among the functions of the control circuit 67, 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 67.

[0074] The driving power supply 70 supplies DC driving power to the active noise canceller 60 .

[0075] The driving power supply 70 may be a DC power supply that can supply DC to the active noise canceller 60 on its own, or may be, for example, 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 its power source.

[0076] [Active noise canceller operation] Next, the operation of the active noise canceller will be described with reference to FIG.

[0077] In this example, for simplicity, the effect of the noise filter 40 in suppressing the common mode current Ic will be ignored.

[0078] 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.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] [First example of power conversion system operation] Next, a first example of the operation of the power conversion system 1 relating to the abnormality diagnosis of the active noise canceller 60 will be described with reference to FIG.

[0083] FIG. 2 is a sequence diagram showing a first example of the operation of the power conversion system 1. As shown in FIG.

[0084] 2, in step S102, the control circuit 33 of the power conversion device 30 sets the operation mode of the power conversion device 30 to a diagnostic mode for diagnosing an abnormality in the active noise canceller 60 at a predetermined timing. The predetermined timing is defined in advance as a timing different from the normal operation of the motor 20. The predetermined timing is, for example, when the motor 20 or a device or system including the motor 20 is started or stopped. When the motor 20 or a device driven by the motor 20 is stopped means when the motor 20 or the device driven by the motor 20 is transitioned from an operating state to a stopped state.

[0085] The diagnostic mode is an operating mode in which the inverter circuit 32 performs a switching operation without rotating the motor 20. For example, in the diagnostic mode, the control circuit 33 causes the inverter circuit 32 to perform a switching operation so as to apply a DC voltage to the motor 20. Alternatively, in the diagnostic mode, the control circuit 33 may cause the inverter circuit 32 to perform a switching operation so as to apply an AC voltage to two of the three phases, U, V, and W, of the motor 20. This allows the control circuit 33 to cause the inverter circuit 32 to perform a switching operation without rotating the motor 20.

[0086] Other functions may be activated simultaneously with the diagnostic mode, which is executed at a predetermined timing. For example, the control circuit 33 may shift to the diagnostic mode and position the rotor of the motor 20 while causing the inverter circuit 32 to perform a switching operation to apply a DC voltage to the motor 20. When the motor 20 drives the compressor 113 (described below), the control circuit 33 may warm the refrigerant or oil by the heat generated by the inverter circuit 32 while causing the inverter circuit 32 to perform a switching operation to apply an AC voltage to two of the three phases of the motor 20. The control circuit 33 may shift to the diagnostic mode and cause the inverter circuit 32 to perform a switching operation to apply an AC voltage to two of the three phases of the motor 20, thereby increasing the temperatures of the switching elements and their peripheral components and suppressing condensation. The control circuit 33 may shift to the diagnostic mode and cause the inverter circuit 32 to perform a switching operation to apply an AC voltage to two of the three phases of the motor 20, thereby generating pulsation in the DC link of the power conversion device 30 due to the AC frequency of the AC power source 10. This allows the control circuit 33 to determine the state of the AC power supply 10 based on various detected values ​​when the DC link is pulsating.

[0087] The control circuit 33 may also transition to the diagnostic mode at a predetermined timing when the inverter circuit 32 is caused to perform a switching operation without rotating the motor 20 in order to activate another function. For example, the control circuit 33 transitions to the diagnostic mode when the timing for positioning the rotor arrives during startup of the motor 20 or the like. The control circuit 33 may also transition to the diagnostic mode when a condition requiring preheating of the refrigerant or oil is met during startup of the compressor 113. The control circuit 33 may also transition to the diagnostic mode when a condition that may cause condensation on the switching elements or their peripheral components is met while the power conversion device 30 is stopped. The control circuit 33 may also transition to the diagnostic mode when a timing for determining the state of the AC power supply 10 arrives.

[0088] When the process of step S102 is completed, the control circuit 33 proceeds to step S104.

[0089] In step S104, the control circuit 33 transmits a signal indicating a notification that the operation mode of the power conversion device 30 has been shifted to the diagnosis mode to the control circuit 67 of the active noise canceller 60 via a predetermined communication line.

[0090] In step S106, the control circuit 67 of the active noise canceller 60 receives the signal transmitted from the control circuit 33 of the power conversion device 30 in step S104.

[0091] When the process of step S106 is completed, the control circuit 67 proceeds to step S108.

[0092] In step S108, the control circuit 67 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.

[0093] 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 the compensation current or the 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. When 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 S108 may be referred to as the "signal to be diagnosed."

[0094] The diagnostic physical quantity is a physical quantity represented by a signal to be diagnosed, such as a current or a voltage.

[0095] When the process of step S108 is completed, the control circuit 67 proceeds to step S110.

[0096] In step S110, the control circuit 67 determines whether the diagnostic conditions related to the physical quantities for diagnosis detected in step S108 are met.

[0097] 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 S108, 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.

[0098] When the process of step S110 is completed, the control circuit 67 proceeds to step S112.

[0099] In step S112, the control circuit 67 performs an abnormality diagnosis of the active noise canceller 60 based on the result of the determination in step S110 as to whether the diagnostic conditions relating to the physical quantities for diagnosis are met.

[0100] For example, the control circuit 67 performs an abnormality diagnosis based on whether a diagnostic condition related to a diagnostic physical quantity is satisfied at a certain point in time in the diagnostic mode. Furthermore, the control circuit 67 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 67 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.

[0101] When the process of step S112 is completed, the control circuit 67 proceeds to step S114.

[0102] In step S114, the control circuit 67 transmits the diagnosis result of the abnormality diagnosis in step S112 to the control circuit 33 of the power conversion device 30 through a predetermined communication line.

[0103] In step S116, the control circuit 33 of the power conversion device 30 receives the diagnosis result transmitted in step S114.

[0104] When the process of step S116 is completed, the control circuit 33 proceeds to step S118.

[0105] In step S118, 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.

[0106] For example, when starting up the motor 20, if the diagnosis result of the abnormality diagnosis of the active noise canceller 60 indicates that the motor 20 is normal, the control circuit 33 transitions to a normal mode for operating the motor 20 normally. On the other hand, if the diagnosis result of the abnormality diagnosis of the active noise canceller 60 indicates that the motor 20 is abnormal, the control circuit 33 transitions to an abnormality stop mode in which the operation of the motor 20 is kept stopped.

[0107] When the process of step S118 is completed, the control circuit 33 proceeds to step S120.

[0108] In step S120, the control circuit 33 notifies the host device of information relating to the abnormality diagnosis.

[0109] 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.

[0110] When the process of step S120 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.

[0111] As described above, in this example, the control circuit 67 performs an abnormality diagnosis of the active noise canceller 60 based on the detection signal of the noise detection means 50 when the switching operation of the inverter circuit 32 is performed without accompanying the rotation operation of the motor 20. This makes it possible to reduce the noise level of the common mode noise caused by the switching operation of the inverter circuit 32 compared to when the switching operation of the inverter circuit 32 is performed with the normal rotation operation of the motor 20. Therefore, even if an abnormality diagnosis of the active noise canceller 60 is performed in a situation where an abnormality exists in the active noise canceller 60, the influence of the common mode noise on other devices connected to the power conversion system 1 can be suppressed.

[0112] Furthermore, in this example, the power conversion system 1 can complete all of the processes of detecting the diagnostic physical quantities, determining whether the diagnostic conditions related to the diagnostic physical quantities are met, and diagnosing anomalies (i.e., the processes of steps S108, S110, and S112) 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 operation mode in accordance with the diagnostic results, which increases the design freedom of the power conversion system 1. For example, even if there are multiple specifications for the active noise canceller 60, the types of content output as diagnostic results are the same, so the control circuit 33 of the power conversion device 30 does not need to perform processing that takes into account the specifications of the active noise canceller 60.

[0113] In this example, the control circuit 33 of the power conversion device 30 may wait for the diagnosis result of the abnormality diagnosis to be transmitted from the control circuit 67 during the diagnosis mode, without transmitting a signal indicating a notification that the operation mode has been switched to the diagnosis mode to the control circuit 67 of the active noise canceller 60. In this case, the processing of steps S104 and S106 is omitted, and the control circuit 67 of the active noise canceller 60 may itself recognize that the power conversion device 30 has switched to the diagnosis mode without relying on a notification from the control circuit 33 of the power conversion device 30, or may always transmit the diagnosis result without itself recognizing it, so that the control circuit 33 of the power conversion device 30 recognizes the diagnosis mode and adopts the diagnosis result during the diagnosis mode.

[0114] [Second example of power conversion system operation] Next, a second example of the operation of the power conversion system 1 regarding the abnormality diagnosis of the active noise canceller 60 will be described with reference to FIG.

[0115] In this example, the description will be centered on the differences from the first example of FIG. 2, and the description of the same or corresponding contents as the first example may be omitted.

[0116] Steps S202 to S210 are the same as steps S102 to S110 in the first example described above, and therefore a description thereof will be omitted.

[0117] When the process of step S210 is completed, the control circuit 67 of the active noise canceller 60 proceeds to step S212.

[0118] In step S212, the control circuit 67 transmits the result of the determination of whether the diagnostic condition in step S210 is satisfied to the control circuit 33 of the power conversion device 30 via a predetermined communication line.

[0119] In step S214, the control circuit 33 of the power conversion device 30 receives the determination result transmitted in step S212.

[0120] When the process of step S214 is completed, the control circuit 33 proceeds to step S216.

[0121] In step S216, the control circuit 33 performs abnormality diagnosis of the active noise canceller 60 in the same manner as in step S112 of the first example described above, based on the result of the determination of whether the diagnostic conditions are met, received in step S216.

[0122] When the process of step S216 is completed, the control circuit 33 proceeds to step S218.

[0123] Steps S218 and S220 are the same as steps S118 and S120 in the first example described above, and therefore a description thereof will be omitted.

[0124] When the process of step S220 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.

[0125] In this way, in this example, the control circuit 33 diagnoses an abnormality in the active noise canceller 60 based on the detection signal of the noise detection means 50 when the switching operation of the inverter circuit 32 is performed without rotating the motor 20. This provides the same functions and effects as the first example described above.

[0126] Furthermore, in this example, the power conversion system 1 can cause the control circuit 67 of the active noise canceller 60 to perform the detection of a diagnostic physical quantity and the process of determining whether a diagnostic condition related to the diagnostic physical quantity is met (i.e., the processes of steps S208 and S210). This allows the control circuit 67 to coordinate the processes from the detection of a diagnostic physical quantity to the determination of whether a diagnostic condition related to the physical quantity is met. Furthermore, because the process of diagnosing an abnormality in 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 configuration of the control circuit 67.

[0127] In this example, the control circuit 33 of the power conversion device 30 may wait, during the diagnostic mode, for the control circuit 67 to transmit a determination result as to whether the diagnostic conditions are met, without transmitting a signal indicating a notification that the operation mode has been shifted to the diagnostic mode to the control circuit 67 of the active noise canceller 60. In this case, the processes of steps S204 and S206 are omitted, and the control circuit 67 of the active noise canceller 60 may itself recognize that the power conversion device 30 has shifted to the diagnostic mode without relying on a notification from the control circuit 33 of the power conversion device 30, or may always transmit a determination result without itself recognizing this, so that the control circuit 33 of the power conversion device 30 recognizes the diagnostic mode and adopts the determination result during the diagnostic mode.

[0128] [Third example of power conversion system operation] Next, a third example of the operation of the power conversion system 1 regarding the abnormality diagnosis of the active noise canceller 60 will be described with reference to FIG.

[0129] In this example, the explanation will be centered on the differences from the first example in FIG. 2 and the second example in FIG. 3 described above, and explanation of the same or corresponding content as the first and second examples described above may be omitted.

[0130] Steps S302 to S308 are the same as steps S102 to S108 in the first example described above, and therefore a description thereof will be omitted.

[0131] When the process of step S308 is completed, the control circuit 67 of the active noise canceller 60 proceeds to step S310.

[0132] In step S310, the control circuit 67 transmits information indicating the physical quantity for diagnosis detected in step S308 to the control circuit 33 of the power conversion device 30 through a predetermined communication line.

[0133] In step S312, the control circuit 33 of the power conversion device 30 receives the information indicating the physical quantity for diagnosis transmitted in step S310.

[0134] In step S314, the control circuit 33 of the power conversion device 30 determines whether the diagnostic conditions for the diagnostic physical quantities are met based on the information representing the diagnostic physical quantities received in step S312, in a manner similar to step S110 in the first example described above.

[0135] When the process of step S314 is completed, the control circuit 33 proceeds to step S316.

[0136] In step S316, the control circuit 33 performs an abnormality diagnosis of the active noise canceller 60 in the same manner as in step S112 of the first example described above, based on the result of the determination of whether the diagnostic conditions relating to the physical parameters for diagnosis are met in step S314.

[0137] When the process of step S316 is completed, the control circuit 33 proceeds to step S318.

[0138] Steps S318 and S320 are the same as steps S118 and S120 in the first example described above, and therefore a description thereof will be omitted.

[0139] When the process of step S320 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.

[0140] In this way, in this example, similar to the second example described above, the control circuit 33 performs an abnormality diagnosis of the active noise canceller 60 based on the detection signal of the noise detection means 50 when the switching operation of the inverter circuit 32 is performed without accompanying the rotation operation of the motor 20. This provides the same functions and effects as the first and second examples described above.

[0141] Furthermore, in this example, the power conversion system 1 can cause the control circuit 33 of the power conversion device 30 to determine whether the diagnostic conditions related to the physical parameters for diagnosis are met and to perform the abnormality diagnosis process (i.e., the processes of steps S314 and S316). This can simplify the configuration of the control circuit 67 of the active noise canceller 60. Furthermore, the control circuit 33 can set more advanced diagnostic conditions using, for example, a microcomputer.

[0142] The control circuit 33 of the power conversion device 30 may wait during the diagnostic mode for information representing the physical quantities for diagnosis to be transmitted from the control circuit 67, without transmitting a signal representing a notification that the operation mode has been switched to the diagnostic mode to the control circuit 67 of the active noise canceller 60. In this case, the processing of steps S304 and S306 is omitted, and the control circuit 67 of the active noise canceller 60 may itself recognize that the power conversion device 30 has switched to the diagnostic mode without relying on a notification from the control circuit 33 of the power conversion device 30, or may always transmit information representing the physical quantities for diagnosis without itself recognizing this, so that the control circuit 33 of the power conversion device 30 recognizes the diagnostic mode and adopts the information during the diagnostic mode.

[0143] [Other examples of power conversion systems] Next, another example of the power conversion system 1 will be described.

[0144] Appropriate modifications and changes may be made to the configuration and operation of the above-described power conversion system 1. Hereinafter, examples in which modifications and changes are made to the configuration and operation of the power conversion system 1 according to the above-described embodiment will be referred to as "modifications" for convenience.

[0145] For example, in the power conversion system 1 of the above-described embodiment, the control circuit 67 may cause the operation of the active noise canceller 60 to differ between when the power conversion device 30 is in the diagnosis mode and when the power conversion device 30 is in another operation mode involving the rotation of the motor 20. For example, when the power conversion device 30 is in the diagnosis mode, the control circuit 67 controls the amplifier circuit 62 so that the degree of amplification (amplification factor) of at least one of the amplifier circuit 62 and the compensation circuit 63 is greater than when the power conversion device 30 is in the other operation mode involving the rotation of the motor 20. This makes it possible to suppress erroneous diagnosis in a situation where the noise level of common-mode noise is relatively lowered in the diagnosis mode, and improve diagnostic accuracy.

[0146] In the power conversion system 1 of the above-described embodiment and its modifications, the AC power supply 10 may supply single-phase AC to the power conversion system 1 instead of three-phase AC.

[0147] 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 a DC link between the rectifier circuit 31 and the inverter circuit 32, including a smoothing capacitor, a smoothing inductor, etc.

[0148] Furthermore, in the power conversion system 1 of the above-described embodiment and its modified examples, 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. Furthermore, some or all of the functions of the control circuit 33 may be transferred to an external device outside the power conversion device 30.

[0149] In the power conversion system 1 of the above-described embodiment and its modified examples, the noise filter 40 may be omitted.

[0150] 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.

[0151] In the power conversion system 1 of the above-described embodiment and its modified examples, the noise detection means 50 may include the function of the filter circuit 61. In this case, the filter circuit 61 is omitted, and the filter circuit in the noise detection means 50 outputs a detection signal from which specific frequency components have been removed, and the detection signal is input to an operational amplifier or the like of the amplification circuit 62.

[0152] In the power conversion system 1 of the above-described embodiment and its modifications, the filter circuit 61 may be omitted.

[0153] 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 67 instead of the amplifier circuit 62, or provided separately from the control circuit 67, 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.

[0154] 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.

[0155] 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.

[0156] 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.

[0157] In the power conversion system 1 of the above-described embodiment and its modified examples, the output unit 64 may have, in addition to the output capacitor Co, a resistor connected in series thereto.

[0158] 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.

[0159] 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.

[0160] 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.

[0161] Furthermore, in the power conversion system 1 of the above-described embodiment and its modifications, the active noise canceller 60 may be provided so that the compensation current Io flows between the DC link of the power conversion circuit 30C and ground GL. For example, as described above, when the driving power supply 70 uses 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 the power path. In this case, the noise detection means 50 may be provided so as to detect common-mode noise on the power line PL1, or so as to detect common-mode noise in the DC link of the power conversion circuit 30C.

[0162] Furthermore, in the power conversion system 1 of the above-described embodiment and its modifications, the active noise canceller 60 may be provided so that compensation current Io flows 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 each of the U-phase, V-phase, and W-phase power lines of the power line PL2. In this case, the noise detection means 50 may be provided so as to detect common mode noise on the power line PL1 or so as to detect common mode noise on the power line PL2.

[0163] 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.

[0164] Furthermore, in the above-described power conversion system 1, other noise detection means may be provided in addition to the noise detection means 50 for diagnosing an abnormality in the active noise canceller 60. In this case, the other noise detection means, like the noise detection means 50, detects common mode noise on the power line PL1, the power line PL2, and the ground GL, and based on the detection signal, an abnormality diagnosis of the active noise canceller 60 is performed.

[0165] Furthermore, in the above-described power conversion system 1, 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.

[0166] [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. 5. Specifically, an air conditioner 100 in which the power conversion system 1 according to this embodiment is installed will be described.

[0167] FIG. 5 is a diagram showing an example of a refrigerant circuit of the air conditioner 100. As shown in FIG.

[0168] 5, 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.

[0169] 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.

[0170] 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.

[0171] 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.

[0172] 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.

[0173] The refrigerant paths L1 to L6 are configured as, for example, pipes.

[0174] The refrigerant path L1 connects one end of the refrigerant path 130 outside the outdoor unit 110 to the four-way switching valve 111.

[0175] 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.

[0176] 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.

[0177] 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.

[0178] 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.

[0179] The refrigerant path L4 connects the four-way switching valve 111 and the outdoor heat exchanger 115.

[0180] The refrigerant path L5 connects the outdoor heat exchanger 115 and the outdoor expansion valve 116.

[0181] The refrigerant path L6 connects one end of the refrigerant path 140 outside the outdoor unit 110 to the outdoor expansion valve 116.

[0182] 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.

[0183] 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.

[0184] 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.

[0185] 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.

[0186] During cooling operation of the air conditioner 100, the four-way switching valve 111 connects the paths indicated by the solid lines in Fig. 5. 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.

[0187] 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. 5. 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.

[0188] 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.

[0189] 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.

[0190] 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.

[0191] 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.

[0192] 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.

[0193] 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.

[0194] 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.

[0195] 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.

[0196] 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.

[0197] The indoor unit 120 includes an indoor expansion valve 121 , an indoor heat exchanger 122 , and a fan 123 .

[0198] 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.

[0199] 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.

[0200] 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.

[0201] 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.

[0202] 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.

[0203] The power conversion system 1 according to this embodiment may be applied to a refrigeration device other than the air conditioner 100.

[0204] [Effect] Next, the operation of the power conversion system and the air conditioner according to this embodiment will be described.

[0205] In a first aspect of this embodiment, a power conversion system includes a power conversion device, a detection means, 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 means is, for example, the noise detection means 50 described above. The noise suppression device is, for example, the active noise canceller 60 described above. The first circuit is, for example, the control circuit 67 or the control circuit 33 described above. Specifically, the power conversion device is connected to an AC power supply and a motor through power lines, and drives the motor with power supplied from the AC power supply by switching a switching element. The AC power supply is, for example, the AC power supply 10 described above. The motor is, for example, the motor 20 described above. The power lines are, for example, the power lines PL1 and PL2 described above. The detection means detects common-mode noise flowing in a path including the power lines due to the switching operation of the switching element, and outputs a detection signal. Furthermore, the noise suppression device outputs a compensation current or compensation voltage to the path based on the detection signal output from the detection means, thereby suppressing the common-mode noise.The first circuit diagnoses an abnormality in the noise suppression device based on a signal related to the state of the common-mode noise when the power conversion device performs the switching operation without rotating the motor.The signal related to the state of the common-mode noise may be, for example, a detection signal from the above-mentioned noise detection means 50 or a signal derived from that detection signal.The signal related to the state of the common-mode noise may also be, for example, a detection signal from noise detection means provided separately from the above-mentioned noise detection means 50 or a signal derived from that detection signal.

[0206] This allows the power conversion system to suppress the common mode noise level when diagnosing an abnormality in the noise suppression device.

[0207] In addition, in a second aspect of this embodiment, based on the first aspect described above, the signal relating to the state of the common mode noise may be a detection signal output from the detection means, or a signal derived from the detection signal.

[0208] This allows the power conversion system 1 to diagnose abnormalities in the noise suppression device using the detection signal of the detection means and a signal derived from the detection signal.

[0209] In a third aspect of the present embodiment, based on the first or second aspect described above, the noise suppression device may include the first circuit, and the first circuit may determine whether a condition for the diagnosis is met using a signal related to the state of the common-mode noise when the power conversion device performs the switching operation without rotating the motor, and perform the diagnosis based on the result of the determination.

[0210] This allows the power conversion system to complete the process for diagnosing abnormalities in the noise suppression device in the noise suppression device. Therefore, even if the noise suppression device has multiple specifications, the power conversion system only needs to determine the operation based on the diagnosis results and does not need to consider differences in specifications. This improves the design flexibility of the power conversion system 1.

[0211] In a fourth aspect of this embodiment, based on the first or second aspect described above, the noise suppression device may include a second circuit. The power conversion device may include the first circuit. The second circuit may determine whether a condition related to the diagnosis is met using a signal related to the state of the common-mode noise when the power conversion device performs the switching operation without rotating the motor. The first circuit may perform the diagnosis based on the determination result of the second circuit.

[0212] This allows the power conversion system to have the power conversion device diagnose any abnormalities in the noise suppression device, thereby simplifying the configuration of the noise suppression device compared to when the diagnosis of abnormalities in the noise suppression device is performed by the noise suppression device itself, for example.

[0213] In a fifth aspect of the present embodiment, based on either the first or second aspect described above, the power conversion device may include the first circuit, and the first circuit may determine whether a condition related to the diagnosis is met using a signal related to the state of the common-mode noise when the power conversion device performs the switching operation not accompanied by the rotation of the motor, and perform the diagnosis based on the result of the determination.

[0214] This allows the power conversion system to have the power conversion device determine whether the diagnostic conditions are met and diagnose any abnormalities in the noise suppression device based on the determination results, thereby simplifying the configuration of the noise suppression device compared to when the noise suppression device itself determines whether the diagnostic conditions are met and diagnoses any abnormalities in the noise suppression device.

[0215] In addition, in a sixth aspect of this embodiment, assuming any one of the first to fifth aspects described above, the power conversion system may include a third circuit that controls the power conversion device for the diagnosis and performs the switching operation without rotating the motor.

[0216] This allows the power conversion system to cause the power conversion device to perform a switching operation that does not involve the rotation of the motor in order to diagnose an abnormality in the noise suppression device.

[0217] In addition, in a seventh aspect of this embodiment, based on any one of the first to sixth aspects described above, the power conversion device may perform the switching operation without rotating the motor so as to apply a DC voltage to the motor.

[0218] This allows the power conversion system 1 to cause the power conversion device to perform a switching operation so as not to rotate the motor.

[0219] In an eighth aspect of the present embodiment, based on any one of the first to sixth aspects, the motor may be driven by three-phase AC, and the power conversion device may perform the switching operation without rotating the motor so as to apply AC voltage to two of the three phases of the motor.

[0220] This allows the power conversion system 1 to cause the power conversion device to perform a switching operation so as not to rotate the motor.

[0221] Furthermore, a ninth aspect of the present embodiment may be based on the first or second aspect described above and further include an amplifier circuit that amplifies a detection signal output from the detection means or a signal output from a filter circuit through which the detection signal passes, and a compensation circuit that outputs the compensation current or the compensation voltage based on the signal output from the amplifier circuit. At least one of the amplifier circuit and the compensation circuit may increase the degree of amplification when the power conversion device performs the switching operation without rotating the motor compared to when the power conversion device performs the switching operation with rotating the motor.

[0222] This allows the power conversion system 1 to improve the accuracy of diagnosis regarding abnormalities in the noise suppression device.

[0223] In addition, in a tenth aspect of this embodiment, based on any one of the first to ninth aspects described above, the noise suppression device may 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 may pass the detection signal output from the detection means and remove specific frequency components. Furthermore, the amplifier circuit may amplify the signal output from the filter circuit. Then, the compensation circuit may output the compensation current or the compensation voltage based on the signal output from the amplifier circuit.

[0224] This allows the noise suppression device to suppress common mode noise in the above-mentioned path including the power line.

[0225] In addition, in an eleventh aspect of this embodiment, based on the second aspect described above, the noise suppression device may include a filter circuit, an amplifier circuit, and a compensation circuit. Specifically, the filter circuit may pass the detection signal output from the detection means and remove specific frequency components. The amplifier circuit may amplify the signal output from the filter circuit. The compensation circuit may output the compensation current or the compensation voltage based on the signal output from the amplifier circuit. The signal derived from the detection signal output from the detection means 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.

[0226] This allows the power conversion system to diagnose abnormalities in the noise suppression device using a signal derived from the detection signal of the detection means.

[0227] In addition, in a twelfth aspect of this embodiment, on the premise of any one of the first to eleventh aspects described above, a wide band gap semiconductor may be used for the switching element.

[0228] This allows the power conversion system to suppress the common mode noise level that accompanies the switching operation of the wide bandgap semiconductor when diagnosing an abnormality in the noise suppression device.

[0229] In addition, in a thirteenth aspect of the present embodiment, an air conditioner may include the power conversion system of any one of the first to twelfth aspects described above. The air conditioner is, for example, the air conditioner 100 described above.

[0230] 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.

[0231] 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]

[0232] 1 Power Conversion System 10 AC power supply 20 Motor 30 Power conversion device 31 Rectifier circuit 32 Inverter circuit 33 Control circuit 40 Noise Filter 50 Noise detection means 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 device (30) connected to an AC power source (10) and a motor (20) via a power line (PL1) and configured to drive the motor (20) with power supplied from the AC power source (10) by switching a switching element; a detection means (50) for detecting common mode noise flowing in a path including the power line (PL1) in association with a switching operation of the switching element, and outputting a detection signal; a noise suppression device (60) that outputs a compensation current or a compensation voltage to the path based on a detection signal output from the detection means (50) to suppress the common mode noise; a first circuit (33, 67) that diagnoses an abnormality in the noise suppression device (60) based on a signal related to the state of the common mode noise when the power conversion device (30) performs the switching operation without rotating the motor (20). Power conversion systems.

2. The signal relating to the state of the common mode noise is a detection signal output from the detection means (50) or a signal derived from the detection signal. The power conversion system of claim 1 .

3. The noise suppression device (60) includes the first circuit (67), The first circuit (67) determines whether a condition related to the diagnosis is met or not using a signal related to the state of the common mode noise when the power conversion device (30) performs the switching operation without rotating the motor (20), and performs the diagnosis based on the determination result. The power conversion system according to claim 1 or 2.

4. The noise suppression device (60) includes a second circuit (67); The power conversion device (30) includes the first circuit (33), the second circuit (67) determines whether the condition for the diagnosis is met by using a signal related to the state of the common mode noise when the power conversion device (30) performs the switching operation without rotating the motor (20); and The first circuit (33) performs the diagnosis based on the determination result of the second circuit (67). The power conversion system according to claim 1 or 2.

5. The power conversion device (30) includes the first circuit (33), The first circuit (33) determines whether the condition for the diagnosis is satisfied or not using a signal related to the state of the common mode noise when the power conversion device (30) performs the switching operation without rotating the motor (20), and performs the diagnosis based on the determination result. The power conversion system according to claim 1 or 2.

6. a third circuit (33) for controlling the power conversion device (30) for the diagnosis and for causing the switching operation to be performed without causing the motor (20) to rotate; The power conversion system according to claim 1 or 2.

7. The power conversion device (30) performs the switching operation without rotating the motor (20) so as to apply a DC voltage to the motor (20). The power conversion system according to claim 1 or 2.

8. The motor (20) is driven by a three-phase alternating current, The power conversion device (30) performs the switching operation without rotating the motor (20) so as to apply an AC voltage to two of the three phases of the motor (20). The power conversion system according to claim 1 or 2.

9. an amplifier circuit (62) for amplifying a detection signal output from the detection means (50) or a signal output from a filter circuit (61) through which the detection signal passes; a compensation circuit (63) that outputs the compensation current or the compensation voltage based on the signal output from the amplifier circuit (62), When the power conversion device (30) performs the switching operation without causing the motor (20) to rotate, the amplifier circuit (62) or the compensation circuit (63) increases the degree of amplification compared to when the power conversion device (30) performs the switching operation with causing the motor (20) to rotate. The power conversion system according to claim 1 or 2.

10. The noise suppression device (60) a filter circuit (61) that passes the detection signal output from the detection means (50) and removes specific frequency components; an amplifier circuit (62) that amplifies the signal output from the filter circuit (61); a compensation circuit (63) that outputs the compensation current or the compensation voltage based on the signal output from the amplifier circuit (62). The power conversion system according to claim 1 or 2.

11. The noise suppression device (60) a filter circuit (61) that passes the detection signal output from the detection means (50) and removes specific frequency components; an amplifier circuit (62) that amplifies the signal output from the filter circuit (61); a compensation circuit (63) that outputs the compensation current or the compensation voltage based on the signal output from the amplifier circuit (62), The signal derived from the detection signal output from the detection means (50) is a signal output from the filter circuit (61), a signal output from the amplifier circuit (62), or a signal representing the compensation current or the compensation voltage output from the compensation circuit (63). The power conversion system of claim 2 .

12. A wide band gap semiconductor is used for the switching element. The power conversion system according to claim 1 or 2.

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

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