State estimation device, drive system, refrigeration system, fan system, state estimation method, and state estimation program

Abstract

To suppress erroneous estimation of a state of an apparatus.SOLUTION: The control unit (31) performs an estimation process of estimating the state of the machine (70) based on first frequency components (C1) among frequency components included in a first signal that is not a signal indicating the DC voltage but a signal correlated with the state of the machine (70), and a limiting process of limiting the estimation process or the operation of the motor (50) so as to prevent erroneous estimation in the estimation process, based on second frequency components (C2) among the frequency components included in the DC voltage, the second frequency components excluding integral multiples of the frequency of the power source voltage. The variation in the amplitudes of the second frequency components (C2) is correlated with the variation in the amplitudes of the first frequency components (C1).SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] The present disclosure relates to state estimation techniques. [Background technology]

[0002] Patent Document 1 discloses an abnormality diagnosis device that diagnoses abnormalities in an electric motor driven by pulse width modulation control of a power conversion device. This abnormality diagnosis device includes a detection unit, an analysis unit, a determination unit, and a frequency setting unit. The detection unit detects the current flowing through the electric motor. The analysis unit performs frequency analysis of the current detected by the detection unit and outputs the analysis result. The determination unit determines an abnormality in the electric motor based on the spectral peak of at least one sideband wave component of the modulated wave obtained from the analysis result. The frequency setting unit sets a noise frequency in the current in advance.

[0003] The frequency setting unit sets the noise frequency to an absolute value that is shifted by an integer multiple of the frequency of the AC power supply to which the power conversion device is connected from an integer multiple of the modulating wave frequency used for pulse width modulation control. The determination unit estimates the presence or absence of noise interference at the spectrum peak of the sideband wave component based on the frequency of the sideband wave component and the set noise frequency, and determines whether an abnormality exists in the motor. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6824494 Summary of the Invention [Problem to be solved by the invention]

[0005] A state estimation device (a device that estimates the state of an equipment) such as the abnormality diagnosis device of Patent Document 1 can only detect noise frequency components of frequencies that are "absolute values ​​shifted by an integer multiple of the frequency of the AC power supply to which the power conversion device is connected from an integer multiple of the modulated wave frequency" as described above, and therefore cannot take into account the influence of frequency components of other frequencies (for example, noise frequency components such as distortion, the frequency at which they appear is difficult to predict).As a result, it is difficult to appropriately suppress erroneous estimation of the state of the equipment. [Means for solving the problem]

[0006] A first aspect of the present disclosure relates to a state estimation device that estimates a state of an appliance (70) equipped with a motor (50) driven by a motor drive device (20) having a DC unit (22) that generates a DC voltage corresponding to a power supply voltage supplied from a power supply (60) and a conversion unit (23) that converts the DC voltage generated by the DC unit (22) into an AC voltage by a switching operation. The state estimation device includes a control unit (31). The control unit (31) performs an estimation process that estimates the state of the appliance (70) based on a first frequency component (C1) among frequency components included in a first signal that is not a signal indicating the DC voltage but is a signal correlated with the state of the appliance (70), and a limitation process that limits the estimation process or operation of the motor (50) to prevent erroneous estimation from being made in the estimation process based on a second frequency component (C2) among frequency components included in the DC voltage that is excluding integer multiples of the frequency of the power supply voltage, and an amplitude fluctuation of the second frequency component (C2) is correlated with an amplitude fluctuation of the first frequency component (C1).

[0007] In the first aspect, by performing the limiting process based on the "second frequency component (C2) included in the DC voltage" that may affect the "first frequency component (C1) included in the first signal that is correlated with the state of the device (70)," it is possible to appropriately limit the estimation process or the operation of the motor (50) so as to prevent erroneous estimation of the state of the device (70) caused by amplitude fluctuations (unintended amplitude fluctuations) of the first frequency component (C1) due to amplitude fluctuations of the DC voltage. This makes it possible to suppress erroneous estimation of the state of the device (70).

[0008] In the first aspect, the frequency of the second frequency component (C2) of the DC voltage used to determine whether or not a limiting process is required is set not to an "integral multiple of the frequency of the power supply voltage" but to "the frequency of the frequency component of the DC voltage that generates amplitude fluctuations correlated with the amplitude fluctuations of the first frequency component (C1) of the first signal used in the estimation process." Therefore, even if the frequency of a noise frequency component that may affect the first frequency component (C1) of the first signal is not an "integral multiple of the frequency of the power supply voltage," the influence of such a noise frequency component can be taken into consideration. This makes it possible to more appropriately suppress erroneous estimation of the state of the device (70) than when an integer multiple of the frequency of the power supply voltage is set as the noise frequency (e.g., in Patent Document 1).

[0009] A second aspect of the present disclosure is a state estimation device of the first aspect, wherein the first signal is a DC signal and the frequency of the second frequency component (C2) is the same as the frequency of the first frequency component (C1).

[0010] A third aspect of the present disclosure is a state estimation device according to the first aspect, wherein the first signal is an AC signal, the frequency of the first frequency component (C1) is a frequency obtained by subtracting a specific frequency from a fundamental frequency of the first signal, or a frequency obtained by adding the specific frequency to the fundamental frequency of the first signal, and the frequency of the second frequency component (C2) is the specific frequency.

[0011] A fourth aspect of the present disclosure is the state estimation device according to any one of the first to third aspects, wherein the restriction process is a process of prohibiting the execution of the estimation process.

[0012] In the fourth aspect, the execution of the estimation process is prohibited, thereby preventing erroneous estimation results, thereby suppressing erroneous estimation of the state of the device (70).

[0013] A fifth aspect of the present disclosure is a state estimation device in which, in the state estimation device of any one of the first to third aspects, the control unit (31) estimates the state of the equipment (70) based on a result of comparison between a variable calculated based on the amplitude of the first frequency component (C1) and a predetermined threshold value in the estimation process, and the limitation process is a process of correcting at least one of the variable and the threshold value so that erroneous estimation is not performed in the estimation process.

[0014] In the fifth aspect, at least one of the variables and the threshold values ​​used in the estimation process is corrected to prevent erroneous estimation results, thereby suppressing erroneous estimation of the state of the device (70).

[0015] A sixth aspect of the present disclosure is a state estimation device according to any one of the first to third aspects, wherein the frequency of the first frequency component (C1) is set to a frequency according to an operating condition of the motor (50), and the limiting process is a process of changing the operating condition of the motor (50) so that erroneous estimation is not performed in the estimation process.

[0016] In the sixth aspect, by changing the operating conditions of the motor (50), it is possible to prevent the first frequency component (C1) included in the first signal correlated with the state of the device (70) from being affected by amplitude fluctuations in the DC voltage. This makes it possible to suppress amplitude fluctuations (unintended amplitude fluctuations) in the first frequency component (C1) caused by amplitude fluctuations in the DC voltage, thereby suppressing erroneous estimation of the state of the device (70).

[0017] A seventh aspect of the present disclosure is the state estimation device of the sixth aspect, wherein the frequency of the first frequency component (C1) is set to a frequency corresponding to a rotational frequency of the motor (50), and the process of changing the operating conditions of the motor (50) is a process of changing the rotational frequency of the motor (50).

[0018] In the seventh aspect, by changing the rotation frequency of the motor (50), it is possible to prevent the first frequency component (C1) included in the first signal correlated with the state of the device (70) from being affected by amplitude fluctuations in the DC voltage. This makes it possible to suppress amplitude fluctuations (unintended amplitude fluctuations) in the first frequency component (C1) caused by amplitude fluctuations in the DC voltage, thereby suppressing erroneous estimation of the state of the device (70).

[0019] An eighth aspect of the present disclosure is the state estimation device according to any one of the first to seventh aspects, wherein the device (70) is one of a compressor, a fan, and a pump.

[0020] A ninth aspect of the present disclosure relates to a drive system including a motor drive device (20) that drives a motor (50) mounted on an appliance (70) and a state estimation device that estimates a state of the appliance (70), wherein the state estimation device is any one of the state estimation devices of the first to seventh aspects.

[0021] A tenth aspect of the present disclosure relates to a refrigeration system including a refrigerant circuit (RR1) including a compressor (CC) having a motor (50), and a state estimation device, wherein the state estimation device is any one of the state estimation devices of the first to seventh aspects and estimates the state of the refrigeration system.

[0022] An eleventh aspect of the present disclosure relates to a fan system including a fan (FF1) having a motor (50) and a state estimation device, wherein the state estimation device is any one of the state estimation devices of the first to seventh aspects and estimates a state of the fan system.

[0023] A twelfth aspect of the present disclosure relates to a state estimation method for estimating a state of an apparatus (70) equipped with a motor (50) driven by a motor drive device (20) having a DC unit (22) that generates a DC voltage corresponding to a power supply voltage supplied from a power supply (60) and a conversion unit (23) that converts the DC voltage generated by the DC unit (22) into an AC voltage by a switching operation. The state estimation method includes an estimation step of estimating the state of the apparatus (70) based on a first frequency component (C1) among frequency components contained in a first signal, which is not a signal indicating the DC voltage but is a signal correlated with the state of the apparatus (70), and a limiting step of limiting the estimation step or operation of the motor (50) based on a second frequency component (C2) among frequency components contained in the DC voltage, excluding an integer multiple of the frequency of the power supply voltage, so as to prevent erroneous estimation in the estimation step, wherein amplitude fluctuations of the second frequency component (C2) are correlated with amplitude fluctuations of the first frequency component (C1).

[0024] In the twelfth aspect, by performing a limiting process based on the "second frequency component (C2) included in the DC voltage" that may affect the "first frequency component (C1) included in the first signal that is correlated with the state of the device (70)," it is possible to appropriately limit the estimation process or the operation of the motor (50) so as to prevent erroneous estimation of the state of the device (70) caused by amplitude fluctuations (unintended amplitude fluctuations) of the first frequency component (C1) due to amplitude fluctuations of the DC voltage. This makes it possible to suppress erroneous estimation of the state of the device (70).

[0025] In the twelfth aspect, the frequency of the second frequency component (C2) of the DC voltage used to determine whether or not a limiting process is required is set not to an "integral multiple of the frequency of the power supply voltage" but to "the frequency of the frequency component of the DC voltage that generates amplitude fluctuations correlated with the amplitude fluctuations of the first frequency component (C1) of the first signal used in the estimation process." Therefore, even if the frequency of a noise frequency component that may affect the first frequency component (C1) of the first signal is not an "integral multiple of the frequency of the power supply voltage," the influence of such a noise frequency component can be taken into consideration. This makes it possible to more appropriately suppress erroneous estimation of the state of the device (70) than when an integer multiple of the frequency of the power supply voltage is set as the noise frequency (for example, in Patent Document 1).

[0026] A thirteenth aspect of the present disclosure relates to a state estimation program that causes a computer to execute the state estimation method of the twelfth aspect. [Brief explanation of the drawings]

[0027] [Figure 1] FIG. 1 is a circuit diagram illustrating the configuration of a drive system according to an embodiment. [Figure 2] FIG. 2 is a waveform diagram illustrating a DC signal and an AC signal. [Figure 3] FIG. 3 is a graph illustrating a first frequency component included in a DC signal. [Figure 4] FIG. 4 is a graph illustrating the first frequency component contained in the AC signal. [Figure 5] FIG. 5 is a waveform diagram illustrating a power supply voltage in which low-frequency pulsation occurs. [Figure 6] FIG. 6 is a graph illustrating low frequency components contained in a power supply voltage. [Figure 7] FIG. 7 is a graph illustrating low frequency components contained in a DC voltage. [Figure 8] FIG. 8 is a graph illustrating low frequency components contained in a DC signal. [Figure 9] FIG. 9 is a flowchart illustrating the flow of processing by the control unit. [Figure 10]FIG. 10 is a flowchart illustrating the first estimation process. [Figure 11] FIG. 11 is a flowchart illustrating the second estimation process. [Figure 12] FIG. 12 is a timing chart illustrating the second estimation process. [Figure 13] FIG. 13 is a flowchart illustrating the third estimation process. [Figure 14] FIG. 14 is a timing chart illustrating the third estimation process. [Figure 15] FIG. 15 is a flowchart illustrating the fourth estimation process. [Figure 16] FIG. 16 is a timing chart illustrating the fourth estimation process. [Figure 17] FIG. 17 is a schematic diagram illustrating the configuration of a refrigeration system. [Figure 18] FIG. 18 is a schematic diagram illustrating the configuration of a fan system. [Figure 19] FIG. 19 is a schematic diagram illustrating the configuration of a pump system. DETAILED DESCRIPTION OF THE INVENTION

[0028] Hereinafter, the embodiments will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference numerals and their description will not be repeated.

[0029] (Embodiment) FIG. 1 illustrates the configuration of a drive system (10) according to an embodiment. The drive system (10) drives a motor (50) using a power supply voltage supplied from a power source (60). The motor (50) is mounted on a device (70). For example, the motor (50) is an interior permanent magnet motor (IPM motor). In this example, the power source (60) is a three-phase AC power supply that supplies a power supply voltage consisting of three-phase AC voltage, and the motor (50) is a three-phase AC motor. The drive system (10) is mounted on a device (70). For example, the device (70) is an outdoor unit of an air conditioner. The drive system (10) includes a motor drive device (20) and a control device (30).

[0030] [Motor drive device] The motor drive device (20) drives the motor (50). Specifically, the motor drive device (20) converts a power supply voltage supplied from a power supply (60) into an output AC voltage (a three-phase AC voltage in this example) having a predetermined frequency and voltage, and supplies the output AC voltage to the motor (50). In this example, the motor drive device (20) includes a converter (21), a DC unit (22), and an inverter (23).

[0031] The converter (21) rectifies the power supply voltage supplied from the power supply (60). In this example, the converter (21) full-wave rectifies the AC voltage supplied from the power supply (60). For example, the converter (21) is configured by a diode bridge circuit in which a plurality of rectifying diodes are connected in a bridge configuration.

[0032] The DC unit 22 generates a DC voltage corresponding to the power supply voltage supplied from the power supply 60. In this example, the DC unit 22 has a capacitor and smoothes the output of the converter 21.

[0033] The inverter (23) has a plurality of switching elements and converts the output of the DC unit (22) into an output AC voltage (a three-phase AC voltage in this example) having a predetermined frequency and voltage through the switching operation of the plurality of switching elements. The inverter (23) is an example of a conversion unit that converts the DC voltage generated by the DC unit (22) into an AC voltage through the switching operation.

[0034] In this example, the inverter (23) has six bridge-connected switching elements and six freewheeling diodes connected in anti-parallel to each of the six switching elements. More specifically, the inverter (23) has three switching legs, each consisting of two switching elements connected in series. The midpoints of the three switching legs (specifically, the connection points between the upper-arm switching element and the lower-arm switching element) are connected to the three windings (U-phase, V-phase, and W-phase windings) of the motor (50), respectively.

[0035] [Various sensors] The motor drive device (20) is provided with various sensors such as a phase current detector (41) and a rotational frequency detector (42) to detect various information (e.g., physical quantities) of the motor drive device (20). The various information detected by the various sensors is transmitted to the control device (30). Specifically, the detection signals of the various sensors are transmitted to a control unit (31) described below.

[0036] The phase current detection unit (41) detects three-phase currents (U-phase current (iu), V-phase current (iv), and W-phase current (iw)) flowing through three windings (not shown) of the motor (50). For example, the phase current detection unit (41) may detect all of the three-phase currents (iu, iv, iw), or may detect two of the three-phase currents (iu, iv, iw) and derive the remaining phase current based on the detected two-phase currents. Alternatively, the phase current detection unit (41) may derive the three-phase currents (iu, iv, iw) from a switching pattern and a DC current detected by a shunt resistor (not shown) provided in the DC unit (22).

[0037] The rotation frequency detection unit (42) detects the rotation frequency (f m The rotation frequency detector (42) is not an essential component, and may be used to detect the rotation frequency (f m ) may be calculated in other ways and estimated sensorlessly.

[0038] The motor drive device (20) is also provided with a DC voltage detection unit (not shown) for detecting the DC voltage generated by the DC unit (22). The DC voltage detected by the DC voltage detection unit is used by the control unit (31) to control the motor (50).

[0039] [Control device (state estimation device)] The control device 30 estimates the state of the device 70. The control device 30 is an example of a state estimation device that estimates the state of the device 70 equipped with the motor 50. The processing in the control device 30 (processing related to the estimation of the state of the device 70) is an example of a state estimation method that estimates the state of the device 70 equipped with the motor 50.

[0040] In this example, the control device (30) estimates whether or not there is an abnormality in the device (70) and takes measures to deal with the abnormality in the device (70). The control device (30) also controls the motor (50). Specifically, the control device (30) controls the motor (50) by controlling the motor drive device (20).

[0041] [Control Unit] The control device (30) includes a control unit (31). The control unit (31) performs various processes. Specifically, the control unit (31) acquires information and data from each part of the device (70) and performs various processes based on the information and data. The processes performed by the control unit (31) will be described in detail later.

[0042] For example, the control unit 31 includes a processor and a memory electrically connected to the processor and storing a program for operating the processor. The processor executes the program to realize various functions of the control unit 31. The control unit 31 is an example of a computer, and the program is an example of a state estimation program.

[0043] [Processing by the control unit] In this example, the control unit (31) performs a control process, a calculation process, an estimation process, and a countermeasure process. Note that these various processes are examples of various steps. For example, the estimation process is an example of an estimation step.

[0044] [Control Processing] In the control process, the control unit (31) controls the motor (50) by controlling the motor drive device (20). Specifically, the control unit (31) controls the rotation frequency (f m ), detection signals of various sensors provided in the motor drive device (20), etc. The control unit (31) then controls the switching operation of the inverter (23) based on the target command value, the detection signals of the various sensors, etc., to control the AC voltage supplied from the inverter (23) to the motor (50).

[0045] [Calculation process] In the calculation process, the control unit (31) calculates the first frequency component (C1) from a first signal, which is not a signal indicating a DC voltage but is a signal correlated with the state of the device (70). For example, the control unit (31) samples the instantaneous value of the "first signal" at a predetermined sampling period and calculates the first frequency component (C1) based on the sampled instantaneous value. The calculation process is an example of a derivation process for deriving the first frequency component (C1) from the first signal. Note that the first signal is a signal whose amplitude fluctuates (in other words, a change appears in the amplitude of the first frequency component (C1)) when the state of the device (70) becomes a predetermined state (a predetermined abnormal state in this example). Specific examples of the first signal and the first frequency component (C1) will be described in detail later.

[0046] [Estimation process] In the estimation process, the control unit (31) estimates the state of the device (70) based on a first frequency component (C1) among the frequency components included in the first signal. Then, the control unit (31) outputs the estimation result. In this example, in the estimation process, the control unit (31) estimates the state of the device (70) based on the first frequency component (C1) calculated by the calculation process. Also in this example, in the estimation process, the control unit (31) estimates the presence or absence of an abnormality in the device (70). A specific example of the estimation process will be described in detail later.

[0047] [Restriction processing] In the limiting process, the control unit (31) limits the estimation process or the operation of the motor (50) to prevent erroneous estimation in the estimation process based on a "second frequency component (C2) excluding an integer multiple of the frequency of the power supply voltage supplied from the power supply (60)" among frequency components included in the DC voltage generated by the DC unit (22). Note that the amplitude fluctuation of the second frequency component (C2) is correlated with the amplitude fluctuation of the first frequency component (C1). Specific examples of the limiting process will be described in detail later.

[0048] [Countermeasures] In the estimation process, when the control unit 31 estimates that the state of the device 70 is an "abnormal state," the control unit 31 performs a countermeasure process. The countermeasure process is a process for dealing with the abnormality of the device 70. For example, the countermeasure process is an output process for outputting first information indicating that the state of the device 70 is an abnormal state.

[0049] Examples of the output process include the following first output process, second output process, third output process, and combinations thereof. The first output process is a process of outputting the first information to a display device (not shown) provided on a remote controller or the like, thereby displaying the first information on the display device. The second output process is a process of outputting the first information to a control unit (not shown) that controls the operation of the device (70), thereby causing the control unit to perform an operation to deal with an abnormal state. The third output process is a process of uploading the first information to a data storage unit (not shown) on the cloud.

[0050] [First frequency component] Next, the first frequency component (C1) included in the first signal will be described. The first frequency component (C1) is a frequency component whose amplitude fluctuates depending on the state of the device 70. Specifically, the first frequency component (C1) is a frequency component whose amplitude changes significantly (for example, the amplitude increases) when the state of the device 70 is in a specific state.

[0051] In this example, the frequency of the first frequency component (C1) is set to a frequency that corresponds to the operating conditions of the motor (50). Examples of the operating conditions of the motor (50) include the rotation frequency of the motor (50) and the fundamental frequency of the motor (50). When the operating conditions of the motor (50) change, the frequency of the first frequency component (C1) changes. Specifically, in this example, the frequency of the first frequency component (C1) is set to a frequency that corresponds to the rotation frequency of the motor (50). For example, the frequency of the first frequency component (C1) is set to n times (n is a positive real number) the rotation frequency of the motor (50).

[0052] The rotational frequency of the motor 50 is the frequency of the mechanical angle of the motor 50. The fundamental frequency of the motor 50 is the frequency of the electrical angle of the motor 50, in other words, the frequency of the current or voltage supplied to the motor 50. The rotational frequency of the motor 50 is correlated with the fundamental frequency of the motor 50, and when the fundamental frequency of the motor 50 changes, the rotational frequency of the motor 50 also changes. Specifically, the fundamental frequency of the motor 50 corresponds to the product of the rotational frequency of the motor 50 and the number of pole pairs of the motor 50.

[0053] The first signal is a DC signal or an AC signal. Fig. 2 illustrates examples of a DC signal and an AC signal. Fig. 2 illustrates an example of a DC signal, which is the "square root of the sum of the squares of the phase currents (iu, iv, iw) of the motor (50)," and an example of an AC signal, which is the "phase currents (iu, iv, iw) of the motor (50)."

[0054] 3, when the first signal is a DC signal, the frequency of the first frequency component (C1) is the frequency of a specific frequency component (Cs). The specific frequency component (Cs) is a frequency component whose amplitude fluctuates depending on the state of the device 70. Specifically, the specific frequency component (Cs) is a frequency component whose amplitude changes significantly (for example, the amplitude increases) when the state of the device 70 is in a specific state.

[0055] For example, the specific frequency component (Cs) is a frequency component that is less than 1 times the rotation frequency (fm) of the motor (50). The frequency of the specific frequency component (Cs) is a frequency obtained by multiplying the rotation frequency (fm) of the motor (50) by a specific ratio. The specific ratio is a fractional ratio expressed as the reciprocal of a natural number. For example, the specific ratio is 1 / 3 or 2 / 3.

[0056] 3, the frequency of the specific frequency component (Cs) is "1 / 3fm" obtained by multiplying the rotation frequency (fm) of the motor (50) by "1 / 3," or "2 / 3fm" obtained by multiplying the rotation frequency (fm) of the motor (50) by "2 / 3." The frequency of the first frequency component (C1) is "1 / 3fm" or "2 / 3fm."

[0057] As shown in Fig. 4, when the first signal is an AC signal, the frequency of the first frequency component (C1) is a frequency (first frequency) obtained by subtracting the frequency of the specific frequency component (Cs) from the fundamental frequency (f0) of the first signal, or a frequency (second frequency) obtained by adding the frequency of the specific frequency component (Cs) to the fundamental frequency (f0) of the first signal. Note that when the first signal is a signal related to the motor (50) (e.g., a signal related to a "phase current of the motor (50)" described below), the fundamental frequency of the first signal corresponds to the fundamental frequency of the motor (50). When the first signal is a signal related to the power supply (60) (e.g., a signal related to a "current flowing between the power supply (60) and the converter (21)" described below), the fundamental frequency of the first signal corresponds to the fundamental frequency of the power supply (60).

[0058] In the example of Fig. 4, the frequency of the specific frequency component (Cs) is "1 / 3fm" obtained by multiplying the rotational frequency (fm) of the motor (50) by "1 / 3". The first frequency is "f0-1 / 3fm", and the second frequency is "f0+1 / 3fm". The frequency of the first frequency component (C1) is "f0-1 / 3fm" or "f0+1 / 3fm".

[0059] As described above, the frequency of the specific frequency component (Cs) is set to a frequency that corresponds to the operating conditions of the motor (50) (e.g., the rotational frequency of the motor (50)). When the operating conditions of the motor (50) change, the frequency of the specific frequency component (Cs) changes, and as a result, the frequency of the first frequency component (C1) changes.

[0060] [Second frequency component] Next, the second frequency component (C2) included in the DC voltage generated by the DC section (22) will be described. The second frequency component (C2) is a frequency component that can affect the amplitude fluctuation of the first frequency component (C1). For example, if an amplitude fluctuation appears in the second frequency component (C2), an amplitude fluctuation also appears in the first frequency component (C1).

[0061] In this example, the frequency of the second frequency component (C2) is set to a frequency corresponding to the frequency of the first frequency component (C1). When the frequency of the first frequency component (C1) changes, the frequency of the second frequency component (C2) also changes.

[0062] Specifically, when the first signal is a DC signal, the frequency of the first frequency component (C1) is set to a specific frequency (the frequency of the specific frequency component (Cs)). The frequency of the second frequency component (C2) is set to a specific frequency that is the same as the frequency of the first frequency component (C1).

[0063] When the first signal is an AC signal, the frequency of the first frequency component (C1) is set to a frequency obtained by subtracting a specific frequency (the frequency of the specific frequency component (Cs)) from the fundamental frequency of the first signal, or a frequency obtained by adding a specific frequency to the fundamental frequency of the first signal, and the frequency of the second frequency component (C2) is set to the specific frequency.

[0064] In this example, the second frequency component (C2) is a frequency component included in the DC voltage excluding an integer multiple of the frequency of the power supply voltage (power supply voltage supplied from the power supply (60)).

[0065] [Findings Obtained by the Inventors of the Present Application] Next, the findings of the present inventors will be described. As a result of extensive research, the present inventors have come to the following findings.

[0066] When amplitude fluctuation occurs in the DC voltage generated by the DC unit (22), the amplitude fluctuation propagates to the motor (50) via the conversion unit (23), and an amplitude fluctuation corresponding to the amplitude fluctuation occurs in the "first signal correlated with the state of the device (70)." Specifically, when the amplitude of a "predetermined frequency component" among the frequency components contained in the DC voltage fluctuates, the amplitude of a "frequency component having a frequency corresponding to the frequency of the predetermined frequency component" among the frequency components contained in the first signal fluctuates.

[0067] Therefore, depending on the frequency of the amplitude fluctuation in the DC voltage, an “unintended amplitude fluctuation” that is not an amplitude fluctuation corresponding to the state of the device 70 may occur in the first frequency component (C1) included in the first signal (a frequency component used in the estimation process). If an unintended amplitude fluctuation occurs in the first frequency component (C1) included in the first signal, the state of the device 70 may be erroneously estimated in the estimation process performed based on the first frequency component (C1).

[0068] For example, when low-frequency pulsation occurs in the power supply voltage as shown in FIG. 5, the power supply voltage contains a low-frequency component (CL) corresponding to the low-frequency pulsation, as shown in FIG. 6. Note that the example in FIG. 5 illustrates only one of the three-phase AC voltages (R-phase voltage, S-phase voltage, and T-phase voltage) that make up the power supply voltage. The low-frequency pulsation is an example of waveform distortion and an example of amplitude fluctuation. For example, a power supply voltage with a fundamental frequency (f0) of 50 Hz may contain a low-frequency pulsation of 17 Hz, which is not an integer multiple of the fundamental frequency (f0) of the power supply voltage (containing a low-frequency component (CL) of 17 Hz). In such cases, a method of setting an integer multiple of the power supply voltage frequency as the noise frequency (for example, the method disclosed in Patent Document 1) cannot handle such noise frequency components.

[0069] 7, the DC voltage generated by the DC unit (22) also contains a low-frequency component (Ca) corresponding to the low-frequency pulsation of the power supply voltage. The frequency of the low-frequency component (Ca) contained in the DC voltage is a frequency (fx) obtained by subtracting the frequency (fL) of the low-frequency component (CL) from the fundamental frequency (f0) of the power supply voltage.

[0070] When amplitude fluctuations occur in the DC voltage, the amplitude fluctuations are propagated to the motor (50) via the converter (23). As a result, the first signal contains a low-frequency component (Cb) corresponding to the low-frequency component (Ca) of the DC voltage, as shown in Fig. 8. In the example of Fig. 8, the first signal is a DC signal, and is, for example, the square root of the sum of the squares of the phase currents (iu, iv, iw) of the motor (50). The frequency of the low-frequency component (Cb) contained in the first signal is the same as the frequency of the low-frequency component (Ca) contained in the DC voltage, and is a frequency (fx) obtained by subtracting the frequency (fL) of the low-frequency component (CL) from the fundamental frequency (f0) of the power supply voltage.

[0071] In the example of FIG. 8, the “frequency (fs) of the first frequency component (C1)” and the “frequency (fx) of the low frequency component (Cb)” are different from each other in the first signal. However, if the “frequency (fs) of the first frequency component (C1)” becomes the same as (or close to) the “frequency (fx) of the low frequency component (Cb)” due to a change in the operating conditions of the motor (50) (for example, a change in the rotation frequency), an unintended amplitude fluctuation (amplitude fluctuation corresponding to low-frequency pulsation) occurs in the first frequency component (C1).

[0072] Examples of factors that can cause amplitude fluctuations in DC voltage include power supply abnormalities, noise, and factors in the DC section.

[0073] Examples of power supply abnormalities include power outages, momentary voltage drops, power supply phase losses, power supply frequency fluctuations, power supply voltage imbalances, and waveform distortions.

[0074] A power outage is a phenomenon in which the power supply voltage supplied from the power supply (60) is momentarily lost. When a power outage occurs, a "frequency component that can affect the first frequency component (C1)" may be superimposed on the DC voltage generated by the DC unit (22) during a transient change in the power supply voltage. An instantaneous voltage drop is a phenomenon in which the power supply voltage is momentarily reduced. A power supply phase loss is a phenomenon in which one of the three-phase AC voltages that make up the power supply voltage is lost. The effects of instantaneous voltage drop and power supply phase loss on the DC voltage are similar to the effects of a power outage on the DC voltage.

[0075] Power supply frequency fluctuation is a phenomenon in which the frequency of the power supply voltage fluctuates instantaneously, causing frequency components (unfixed frequency components) corresponding to the fluctuation to be superimposed on the power supply voltage. Power supply voltage imbalance is a phenomenon in which the amplitudes and phase differences of the three-phase AC voltages that make up the power supply voltage are different from each other. Waveform distortion is a phenomenon in which frequency components other than the fundamental wave component of the power supply voltage are superimposed on the power supply voltage. When unintended frequency components are superimposed on the power supply voltage in this way, there is a possibility that "frequency components that may affect the first frequency component (C1)" will be superimposed on the DC voltage generated by the DC section (22).

[0076] Examples of noise include induction noise between wirings, common mode noise, etc. If such noise is superimposed on the DC voltage of the DC section (22), there is a possibility that a "frequency component that can affect the first frequency component (C1)" will be generated in the DC voltage.

[0077] Examples of factors in the DC section include fluctuations in the DC voltage (the DC voltage generated by the DC section (22)) due to resonance, fluctuations in the DC voltage due to disturbances, etc. When the DC voltage fluctuates in this way, there is a possibility that a "frequency component that can affect the first frequency component (C1)" may be superimposed on the DC voltage.

[0078] Based on the above-described new findings, the inventors of the present application have discovered that, among the frequency components contained in the DC voltage generated by the DC unit (22), "a frequency component that may affect the first frequency component (C1) contained in the first signal correlated with the state of the device (70)" is defined as a "second frequency component (C2)," and have discovered that a process of "limiting the estimation process or the operation of the motor (50) based on the second frequency component (C2) so as to prevent erroneous estimation in the estimation process" is performed. The second frequency component (C2) is a frequency component for checking whether unintended amplitude fluctuations occur in the first frequency component (C1).

[0079] [Processing flow by the control unit] Next, with reference to FIG. 9, the flow of the processes (specifically, the calculation process, the estimation process, and the restriction process) performed by the control unit (31) will be described.

[0080] The control unit (31) performs a calculation process at each predetermined calculation time. The calculation process is repeated to calculate the first frequency component (C1) at each calculation time. For example, the calculation time is set to a time equal to or longer than the time required to calculate the first frequency component (C1) from the first signal.

[0081] The control unit (31) then performs an estimation process based on the first frequency component (C1) calculated by the calculation process for each predetermined estimation time. The estimation process is repeated to obtain an estimation result for each estimation time. The estimation time is set to a time equal to or longer than the calculation time. For example, the estimation time is set to a time equal to or longer than the time required to estimate the state of the device (70) based on the first frequency component (C1) calculated by the calculation process.

[0082] Furthermore, the control unit (31) performs a limiting process in parallel with the calculation process and the estimation process. Specifically, the control unit (31) repeatedly performs the processes of steps (S101 to S104) shown in FIG.

[0083] <Step (S101): Restriction Determination Process> The control unit (31) calculates the second frequency component (C2). For example, the control unit (31) samples the instantaneous value of the "electrical signal corresponding to the DC voltage" at a predetermined sampling period and calculates the second frequency component (C2) based on the sampled instantaneous value. Then, the control unit (31) determines whether or not a restriction execution condition based on the second frequency component (C2) is satisfied. Note that the electrical signal corresponding to the DC voltage is, for example, a detection signal (a signal indicating the DC voltage) output from a DC voltage detection unit (not shown) that detects the DC voltage. The restriction execution condition based on the second frequency component (C2) will be described in detail later.

[0084] When the restriction execution condition based on the second frequency component (C2) is satisfied, the process of step (S102) is performed. For example, the process of step (S101) is performed at predetermined determination time intervals. In other words, the process of step (S101) is repeatedly performed until the restriction execution condition based on the second frequency component (C2) is satisfied.

[0085] <Step (S102): Restriction Execution Processing> When the restriction execution condition based on the second frequency component (C2) is met, the control unit (31) restricts the estimation process or the operation of the motor (50) so as to prevent erroneous estimation from being made in the estimation process.

[0086] <Step (S103): Cancellation Determination Process> Next, the control unit (31) determines whether a restriction release condition is satisfied. Examples of the restriction release condition include a condition that a restriction execution condition based on the second frequency component (C2) is no longer satisfied, and a condition that the control unit (31) receives a release command. The release command is transmitted from an operation unit (not shown) to the control unit (31) when an operator inputs an operation to release the restriction to the operation unit (not shown).

[0087] When the restriction removal condition is met, the process of step (S104) is performed. For example, the process of step (S103) is performed at predetermined intervals. In other words, the process of step (S103) is repeatedly performed until the restriction removal condition is met.

[0088] <Step (S104): Restriction Release Processing> When the restriction removal condition is met, the control unit (31) removes the restriction (restriction on the estimation process or restriction on the operation of the motor (50)).

[0089] [Effects of the embodiment] As described above, in the embodiment, the control unit (31) performs an estimation process to estimate the state of the device (70) based on the first frequency component (C1) among frequency components included in the first signal, which is not a signal indicating a DC voltage but is a signal correlated with the state of the device (70), and a limitation process to limit the estimation process or the operation of the motor (50) to prevent erroneous estimation in the estimation process based on the second frequency component (C2) among frequency components included in the DC voltage, which is a frequency component excluding integer multiples of the frequency of the power supply voltage (power supply voltage supplied from the power source (60)). The amplitude fluctuation of the first frequency component (C1) is correlated with the amplitude fluctuation of the second frequency component (C2).

[0090] In the above configuration, the limitation process is performed based on the "second frequency component (C2) included in the DC voltage" that may affect the "first frequency component (C1) included in the first signal that is correlated with the state of the device (70)." This makes it possible to appropriately limit the estimation process or the operation of the motor (50) so as to prevent erroneous estimation of the state of the device (70) due to amplitude fluctuations (unintended amplitude fluctuations) of the first frequency component (C1) caused by amplitude fluctuations of the DC voltage. This makes it possible to suppress erroneous estimation of the state of the device (70). For example, it is possible to prevent erroneous estimation of the device (70) as being abnormal.

[0091] In the embodiment, the frequency of the second frequency component (C2) of the DC voltage used to determine whether or not a limiting process is required is set not to an "integral multiple of the frequency of the power supply voltage" but to "the frequency of the frequency component of the DC voltage that generates amplitude fluctuations correlated with the amplitude fluctuations of the first frequency component (C1) of the first signal used in the estimation process." Therefore, even if the frequency of a noise frequency component that may affect the first frequency component (C1) of the first signal is not an "integral multiple of the frequency of the power supply voltage," the influence of such a noise frequency component can be taken into consideration. This makes it possible to more appropriately suppress erroneous estimation of the state of the device (70) than when an integer multiple of the frequency of the power supply voltage is set as the noise frequency (e.g., in Patent Document 1).

[0092] In addition, in the embodiment, since the second frequency component (C2) of the DC voltage is monitored, it is not necessary to monitor all frequency components of the DC voltage, and therefore the processing load (e.g., calculation load) required to monitor the frequency components of the DC voltage can be reduced compared to when all frequency components of the DC voltage are monitored.

[0093] Furthermore, when the first signal is an AC signal and a first frequency component (C1) of the AC signal is monitored, the first frequency component (C1) becomes closer to the fundamental frequency component centered on the fundamental frequency (f0) of the AC signal. For example, the first frequency component (C1) appears as a sideband of the fundamental frequency component. The fundamental frequency component has a frequency width. Therefore, the closer the first frequency component (C1) is to the fundamental frequency component, the more susceptible the first frequency component (C1) is to the fundamental frequency component, making it difficult to separate the first frequency component (C1) from the fundamental frequency component. For example, when the first signal is an AC signal, a filter with a steep attenuation slope is required to separate the first frequency component (C1) from the fundamental frequency component, but implementing such a filter is difficult. Furthermore, since the first frequency component (C1) appears separated into two sidebands of the fundamental frequency component, the amplitude of the first frequency component (C1) of the AC signal is smaller than the amplitude of the first frequency component (C1) of the DC signal.

[0094] On the other hand, when the first signal is a DC signal and the first frequency component (C1) of the DC signal is monitored, the fundamental frequency component of the DC signal is a DC amount. When the first signal is a DC signal, the fundamental frequency component is a zero Hz component that can be obtained by simple processing such as averaging, so the fundamental frequency component and the first frequency component (C1) can be easily separated by simple calculation. Furthermore, since the amplitude of the first frequency component (C1) of a DC signal is larger than the amplitude of the first frequency component (C1) of an AC signal, the signal-to-noise ratio of the first frequency component (C1) can be improved. This improves the accuracy of the first frequency component (C1). Note that, since the amplitude of the first frequency component (C1) is small to begin with, it is preferable to convert it to DC to improve the signal-to-noise ratio.

[0095] As described above, when the first signal is a DC signal (when the first frequency component (C1) of the DC signal is monitored), it is easier to extract the first frequency component (C1) than when the first signal is an AC signal (when the first frequency component (C1) of the AC signal is monitored).

[0096] Furthermore, in the embodiment, the limiting process is performed based on the DC voltage, and therefore the sensor provided for detecting the DC voltage (DC voltage detection unit) can be used not only for controlling the motor (50) but also for the limiting process. Because the sensor can be used for both purposes in this way, the number of parts can be reduced, and costs can be reduced, compared to when a separate sensor is provided for the limiting process (for example, when a sensor is provided for detecting the power supply voltage in order to perform the limiting process based on the power supply voltage).

[0097] (Example of the first signal) Next, a description will be given of specific examples of the first signal correlated with the state of the device 70. The first signal is broadly classified into a DC signal and an AC signal.

[0098] [Example of DC signal] Examples of DC signals include a "signal correlated to the phase currents (iu, iv, iw) of the motor (50)," a "signal correlated to the phase voltages (Vu, Vv, Vw) of the motor (50)," and a "signal correlated to the power of the motor (50)."

[0099] Other examples of DC signals include "currents (iγ, iδ) obtained by coordinate transformation of the phase currents (iu, iv, iw) of the motor (50) with the phase (ωi·t) of the phase currents (iu, iv, iw) of the motor (50)" and "voltages (Vγ, Vδ) obtained by coordinate transformation of the phase voltages (Vu, Vv, Vw) of the motor (50) with the phase (ωv·t) of the phase voltages (Vu, Vv, Vw) of the motor (50)." )," "currents (iζ, iη) obtained by coordinate transformation of the phase currents (iu, iv, iw) of the motor (50) with the phase (ωv·t) of the phase voltages (Vu, Vv, Vw) of the motor (50)," and "voltages (Vζ, Vη) obtained by coordinate transformation of the phase voltages (Vu, Vv, Vw) of the motor (50) with the phase (ωi·t) of the phase currents (iu, iv, iw) of the motor (50)."

[0100] Further examples of DC signals include "dq-axis magnetic flux (λd, λq) coordinate-transformed to match the armature flux linkage caused by the permanent magnet" and "the magnitude of the armature flux linkage vector λ0, which is the composite of the armature flux linkage of the permanent magnet and the armature reaction."

[0101] In the following description, the term "phase currents (iu, iv, iw) of the motor (50)" refers to the phase currents (iu, iv, iw) of the motor (50) detected by the phase current detection unit (41). The term "phase voltages (Vu, Vv, Vw) of the motor (50)" refers to the phase voltages (Vu, Vv, Vw) of the motor (50) indicated in a voltage command value used within the control unit (31) or the phase voltages (Vu, Vv, Vw) of the motor (50) detected by a phase voltage detection unit (not shown) provided in the motor drive device (20). The term "electrical angular frequency (ω) of the motor (50)" refers to the electrical angular frequency (ω) of the motor (50) detected by an electrical angular frequency detection unit (not shown). The electrical angular frequency (ω) may be calculated by other methods or estimated sensorlessly.

[0102] [1. Specific examples of signals correlated with motor phase currents] Specific examples of signals correlated with the phase currents (iu, iv, iw) of the motor (50) include the current vector amplitude (Ia), the square of the current vector amplitude (Ia 2 ), phase current amplitude (I), and phase current effective value (Irms).

[0103] The current vector amplitude (Ia) and the square of the current vector amplitude (Ia 2 ) is an example of a value proportional to the sum of the squares of the three phase currents (iu, iv, iw) of the motor (50). The value proportional to the sum of the squares of the three phase currents (iu, iv, iw) of the motor (50) is an example of a value proportional to an integer power of the magnitude of the phase currents (iu, iv, iw) of the motor (50).

[0104] (1) Current vector amplitude The current vector amplitude (Ia) is derived based on the phase currents (iu, iv, iw) of the motor (50). Alternatively, the current vector amplitude (Ia) may be derived based on an α-phase current (iα) and a β-phase current (iβ) obtained by transforming the phase currents (iu, iv, iw) of the motor (50) into a fixed coordinate system. Alternatively, the current vector amplitude (Ia) may be derived based on an M-axis current (iM) and a T-axis current (iT) obtained by coordinate transforming the phase currents (iu, iv, iw) of the motor (50) using an angle based on the direction of the primary magnetic flux. Alternatively, the current vector amplitude (Ia) may be derived based on a d-axis current (id) and a q-axis current (iq) obtained by coordinate transforming the phase currents (iu, iv, iw) of the motor (50) using an angle based on the direction of the magnetic pole position. Specifically, the current vector amplitude (Ia) can be expressed as follows:

[0105]

number

[0106] (2) Square of the current vector amplitude The squared value of the current vector amplitude (Ia 2) is derived based on the phase currents (iu, iv, iw) of the motor (50). 2 ) may be derived based on the α-phase current (iα) and the β-phase current (iβ) obtained by transforming the phase currents (iu, iv, iw) of the motor (50) into a fixed coordinate system. 2 ) may be derived based on the M-axis current (iM) and the T-axis current (iT) obtained by coordinate transformation of the phase currents (iu, iv, iw) of the motor (50) by an angle based on the direction of the primary magnetic flux. 2 ) may be derived based on the d-axis current (id) and the q-axis current (iq) obtained by coordinate transformation of the phase currents (iu, iv, iw) of the motor (50) by an angle based on the orientation of the magnetic pole position. Specifically, the square value of the current vector amplitude (Ia 2 ) can be expressed as the following formula:

[0107]

number

[0108] (3) Phase current amplitude The phase current amplitude (I) is derived based on one of the phase currents (iu, iv, iw) of the motor (50), for example, the U-phase current (iu), and the phase current phase (ωi·t). The phase current phase (ωi·t) is derived based on the phase currents (iu, iv, iw) of the motor (50), for example. Specifically, the phase current amplitude (I) can be expressed by the following equation:

[0109]

number

[0110] (4) Phase current effective value The phase current effective value (Irms) is derived based on the phase current amplitude (I). Specifically, the phase current effective value (Irms) can be expressed as follows:

[0111]

number

[0112] (5) Other In the above description, the case where the current vector amplitude (Ia) is derived based on the three phase currents (iu, iv, iw) of the motor (50) has been exemplified. However, the current vector amplitude (Ia) may be derived based on two of the three phase currents (iu, iv, iw) of the motor (50). The current vector amplitude (Ia) may also be derived based on a DC current of the inverter (23) detected by a DC current detector (e.g., a shunt resistor, not shown) provided in the motor drive device (20). The square value (Ia) of the current vector amplitude 2 ) is also the same.

[0113] [2. Specific examples of signals correlated with motor phase voltages] Specific examples of signals correlated with the phase voltages (Vu, Vv, Vw) of the motor (50) include voltage vector amplitude (Va), squared value of voltage vector amplitude (Va 2 ), phase voltage amplitude (V), and phase voltage effective value (Vrms).

[0114] The voltage vector amplitude (Va) and the square of the voltage vector amplitude (Va 2 ) is an example of a value proportional to the sum of the squares of the three phase voltages (Vu, Vv, Vw) of the motor (50). The value proportional to the sum of the squares of the three phase voltages (Vu, Vv, Vw) of the motor (50) is an example of a value proportional to an integer power of the magnitude of the phase voltages (Vu, Vv, Vw) of the motor (50).

[0115] (1) Voltage vector amplitude The voltage vector amplitude (Va) is derived based on the phase voltages (Vu, Vv, Vw) of the motor (50). Alternatively, the voltage vector amplitude (Va) may be derived based on an α-phase voltage (Vα) and a β-phase voltage (Vβ) obtained by transforming the phase voltages (Vu, Vv, Vw) of the motor (50) into a fixed coordinate system. Alternatively, the voltage vector amplitude (Va) may be derived based on an M-axis voltage (VM) and a T-axis voltage (VT) obtained by coordinate transforming the phase voltages (Vu, Vv, Vw) of the motor (50) by an angle based on the direction of the primary magnetic flux. Alternatively, the voltage vector amplitude (Va) may be derived based on a d-axis voltage (Vd) and a q-axis voltage (Vq) obtained by coordinate transforming the phase voltages (Vu, Vv, Vw) of the motor (50) by an angle based on the direction of the magnetic pole position. Specifically, the voltage vector amplitude (Va) can be expressed as follows:

[0116]

number

[0117] (2) Squared value of voltage vector amplitude The squared value of the voltage vector magnitude (Va 2 ) is derived based on the phase voltages (Vu, Vv, Vw) of the motor (50). 2 ) may be derived based on the α-phase voltage (Vα) and the β-phase voltage (Vβ) obtained by transforming the phase voltages (Vu, Vv, Vw) of the motor (50) into a fixed coordinate system. 2 ) may be derived based on the M-axis voltage (VM) and the T-axis voltage (VT) obtained by coordinate transformation of the phase voltages (Vu, Vv, Vw) of the motor (50) by an angle based on the direction of the primary magnetic flux. 2 ) may be derived based on the d-axis voltage (Vd) and the q-axis voltage (Vq) obtained by coordinate transformation of the phase voltages (Vu, Vv, Vw) of the motor (50) by an angle based on the orientation of the magnetic pole position. Specifically, the square value of the voltage vector amplitude (Va 2 ) can be expressed as the following formula:

[0118]

number

[0119] (3) Phase voltage amplitude The phase voltage amplitude (V) is derived based on one of the phase voltages (Vu, Vv, Vw) of the motor (50), for example, the U-phase voltage (Vu), and the phase voltage phase (ωv·t). The phase voltage phase (ωv·t) is derived based on the phase voltages (Vu, Vv, Vw) of the motor (50), for example. Specifically, the phase voltage amplitude (V) can be expressed by the following equation:

[0120]

number

[0121] (4) Phase voltage effective value The phase voltage effective value (Vrms) is derived based on the phase voltage amplitude (V). Specifically, the phase voltage effective value (Vrms) can be expressed as follows:

[0122]

number

[0123] (5) Other In the above description, an example has been given in which the voltage vector amplitude (Va) is derived based on the three phase voltages (Vu, Vv, Vw) of the motor (50). However, the voltage vector amplitude (Va) may be derived based on two of the three phase voltages (Vu, Vv, Vw) of the motor (50). 2 ) is also the same.

[0124] [3. Specific examples of signals correlated with motor power] Examples of signals correlated to the power of the motor (50) include instantaneous power (p), instantaneous imaginary power (q), apparent power (S), active power (P), and reactive power (Q).

[0125] (1) Instantaneous power The instantaneous power (p) is derived based on the phase currents (iu, iv, iw) of the motor (50) and the phase voltages (Vu, Vv, Vw) of the motor (50). Alternatively, the instantaneous power (p) may be derived based on an α-phase current (iα) and a β-phase current (iβ) obtained by transforming the phase currents (iu, iv, iw) of the motor (50) into a fixed coordinate system, and an α-phase voltage (Vα) and a β-phase voltage (Vβ) obtained by transforming the phase voltages (Vu, Vv, Vw) of the motor (50) into the fixed coordinate system. The instantaneous power (p) may be derived based on an M-axis current (iM) and a T-axis current (iT) obtained by coordinate transforming the phase currents (iu, iv, iw) of the motor (50) using an angle based on the direction of the primary magnetic flux, and an M-axis voltage (VM) and a T-axis voltage (VT) obtained by coordinate transforming the phase voltages (Vu, Vv, Vw) of the motor (50) using an angle based on the direction of the primary magnetic flux. The instantaneous power (p) may be derived based on a d-axis current (id) and a q-axis current (iq) obtained by coordinate transforming the phase currents (iu, iv, iw) of the motor (50) using an angle based on the direction of the magnetic pole position, and a d-axis voltage (Vd) and a q-axis voltage (Vq) obtained by coordinate transforming the phase voltages (Vu, Vv, Vw) of the motor (50) using an angle based on the direction of the magnetic pole position. Specifically, the instantaneous power (p) can be expressed as follows:

[0126]

number

[0127] (2) Instantaneous reactive power The instantaneous imaginary power (q) is derived based on an α-phase current (iα) and a β-phase current (iβ) obtained by transforming the phase currents (iu, iv, iw) of the motor (50) into a fixed coordinate system, and an α-phase voltage (Vα) and a β-phase voltage (Vβ) obtained by transforming the phase voltages (Vu, Vv, Vw) of the motor (50) into a fixed coordinate system. Alternatively, the instantaneous imaginary power (q) may be derived based on an M-axis current (iM) and a T-axis current (iT) obtained by coordinate transforming the phase currents (iu, iv, iw) of the motor (50) by an angle based on the direction of the primary magnetic flux, and an M-axis voltage (VM) and a T-axis voltage (VT) obtained by coordinate transforming the phase voltages (Vu, Vv, Vw) of the motor (50) by an angle based on the direction of the primary magnetic flux. Furthermore, the instantaneous imaginary power (q) may be derived based on a d-axis current (id) and a q-axis current (iq) obtained by coordinate transforming the phase currents (iu, iv, iw) of the motor (50) by an angle based on the orientation of the magnetic pole positions, and a d-axis voltage (Vd) and a q-axis voltage (Vq) obtained by coordinate transforming the phase voltages (Vu, Vv, Vw) of the motor (50) by an angle based on the orientation of the magnetic pole positions. Specifically, the instantaneous imaginary power (q) can be expressed by the following equation:

[0128]

number

[0129] (3) Apparent power The apparent power (S) is calculated based on the phase voltage effective value (Vrms) and the phase current effective value (Irms). Specifically, the apparent power (S) can be expressed as follows:

[0130]

number

[0131] (4) Active power Active power (P) is calculated based on the phase voltage effective value (Vrms), the phase current effective value (Irms), and the phase difference (φ1) between the phase voltage and the phase current. The phase difference (φ1) between the phase voltage and the phase current is the phase difference between one phase voltage (e.g., U-phase voltage (Vu)) and one phase current (e.g., U-phase current (iu)), and is calculated based on the phase of the phase current (ωi·t) and the phase of the phase voltage (ωv·t). Specifically, active power (P) can be expressed as follows:

[0132]

number

[0133] (5) Reactive power The reactive power (Q) is calculated based on the phase voltage effective value (Vrms), the phase current effective value (Irms), and the phase difference (φ1) between the phase voltage and the phase current. The phase difference (φ1) between the phase voltage and the phase current is, for example, the phase difference between the U-phase voltage (Vu) and the U-phase current (iu), and is calculated based on the phase of the phase current (ωi·t) and the phase of the phase voltage (ωv·t). Specifically, the reactive power (Q) can be expressed as follows:

[0134]

number

[0135] [4. Current obtained by coordinate transformation of phase current with the phase of the phase current] The currents (iγ, iδ) obtained by coordinate transformation of the phase currents (iu, iv, iw) of the motor (50) using the phase (ωi·t) of the phase currents (iu, iv, iw) of the motor (50) can be expressed by the following equations.

[0136]

number

[0137] [5. Voltage obtained by coordinate transformation of phase voltage with the phase of the phase voltage] The voltages (Vγ, Vδ) obtained by coordinate transformation of the phase voltages (Vu, Vv, Vw) of the motor (50) using the phase (ωv·t) of the phase voltages (Vu, Vv, Vw) of the motor (50) can be expressed by the following equations:

[0138]

number

[0139] [6. Current obtained by coordinate transformation of phase current with the phase voltage] The currents (iζ, iη) obtained by coordinate transformation of the phase currents (iu, iv, iw) of the motor (50) using the phase (ωv·t) of the phase voltages (Vu, Vv, Vw) of the motor (50) can be expressed by the following equations:

[0140]

number

[0141] [7. Voltage obtained by coordinate transformation of phase voltage with the phase current] The voltages (Vζ, Vη) obtained by coordinate transformation of the phase voltages (Vu, Vv, Vw) of the motor (50) using the phases (ωi·t) of the phase currents (iu, iv, iw) of the motor (50) can be expressed by the following equations:

[0142]

number

[0143] [6. Magnitude of dq-axis magnetic flux and armature interlinkage magnetic flux vector] The dq-axis magnetic flux (λd, λq) coordinate-transformed to match the armature flux linkage caused by the permanent magnet, and the magnitude λ0 of the armature flux linkage vector, which is the composite of the armature flux linkage of the permanent magnet and the armature reaction, can be expressed as follows: In the following equation, "Ld" is the d-axis inductance, and "Lq" is the q-axis inductance.

[0144]

number

[0145] [7. Other examples of DC signals] The DC signal may be a DC signal obtained by performing a three-phase to two-phase conversion on the phase current, phase voltage, line current, or line voltage of the motor (50) and then performing a rotational coordinate conversion. For example, the DC signal may be a d-axis current and a q-axis current obtained by performing a rotational coordinate conversion on the α-axis current and the β-axis current obtained by performing a three-phase to two-phase conversion on the phase current of the motor (50) at an angle based on the orientation of the magnetic poles of the rotor of the motor (50). The DC signal may be an M-axis current and a T-axis current obtained by performing a rotational coordinate conversion on the α-axis current and the β-axis current at an angle based on the orientation of the primary magnetic flux of the rotor of the motor (50).

[0146] The DC signal may also be the power input to the converter (21) of the motor drive device (20), the power output from the converter (21), the power output from the DC unit (22), the current flowing between the converter (21) and the DC unit (22), the current flowing between the DC unit (22) and the inverter (23), etc.

[0147] [Example of AC signal] Examples of AC signals include "phase currents (iu, iv, iw) of the motor (50)," "phase voltages (Vu, Vv, Vw) of the motor (50)," and "flux linkages of each phase (Ψfu, Ψfv, Ψfw)."

[0148] The interlinkage magnetic flux of each phase (Ψfu, Ψfv, Ψfw) can be expressed as follows:

[0149]

number

[0150] Another example of an AC signal is a current or voltage flux linkage of fixed coordinates obtained by three-phase to two-phase conversion of the AC signal.

[0151] The AC signal may be a line current, a line voltage, or the like of the motor (50). The AC signal may be a two-phase AC current (e.g., an α-axis current and a β-axis current) or a two-phase AC voltage obtained by three-phase to two-phase conversion of a phase current, a phase voltage, a line current, or a line voltage. The AC current may be a current flowing between a commercial power supply system (specifically, a power supply (60)) and the converter (21) of the motor drive device (20), or a current flowing between the inverter (23) of the motor drive device (20) and the motor (50).

[0152] (Example of the first frequency component) Next, a specific example of the first frequency component (C1) will be described.

[0153] For example, when the first signal is a DC signal, the frequency of the first frequency component (C1) is at least one of 1, 1 / 3, and 2 / 3 times the rotational frequency of the motor (50). When the first signal is an AC signal, the frequency of the first frequency component (C1) is at least one of a frequency obtained by adding a predetermined frequency to the fundamental frequency of the first signal, a frequency obtained by subtracting a predetermined frequency from the fundamental frequency of the first signal, and three times the fundamental frequency of the first signal. The predetermined frequency is one of 1, 1 / 3, and 2 / 3 times the rotational frequency of the motor (50).

[0154] By setting the frequency of the first frequency component (C1) as described above, various states (particularly abnormalities) of the device (70) can be estimated.

[0155] (Various equipment conditions) Here, various states of the device (70) will be described. Examples of the states of the device (70) include breakdown of the oil seal of the compression chamber, insulation deterioration of the motor (50), bearing wear, dilution, liquid compression, imbalance, and blockage of the flow path. These states of the device (70) are examples of abnormalities of the device (70).

[0156] [1. Compression chamber oil seal failure] The breakdown of the oil seal in the compression chamber is a condition that can occur when the motor (50) is a "motor (50) mounted on a compressor," and is a condition in which there is a shortage of lubricating oil to seal the compression chamber (not shown) in the compressor.

[0157] When the first signal is a DC signal, if an oil seal in a compression chamber breaks down, the frequency component corresponding to one time the rotation frequency of the motor (50) tends to decrease. Therefore, when the first signal is a DC signal, by setting the frequency of the first frequency component (C1) to one time the rotation frequency of the motor (50), it is possible to estimate the occurrence of an oil seal breakage in a compression chamber.

[0158] Furthermore, when the first signal is an AC signal, if an oil seal in a compression chamber breaks down, the frequency component corresponding to the frequency obtained by adding "one time the rotation frequency of the motor (50)" to the fundamental frequency of the first signal and the frequency component corresponding to the frequency obtained by subtracting "one time the rotation frequency of the motor (50)" from the fundamental frequency of the first signal tend to decrease. Therefore, when the first signal is an AC signal, "breakdown of the oil seal in a compression chamber" can be estimated by setting the frequency of the first frequency component (C1) to the frequency obtained by adding "one time the rotation frequency of the motor (50)" to the fundamental frequency of the first signal or the frequency obtained by subtracting "one time the rotation frequency of the motor (50)" from the fundamental frequency of the first signal.

[0159] [2. Motor insulation deterioration] Deterioration of the insulation of the motor (50) is a state (abnormality) in which the insulation performance of the motor (50) is insufficient. As the deterioration of the insulation performance of the motor (50) progresses, the insulation level of the motor (50) falls below an allowable level.

[0160] When the first signal is an AC signal related to the motor (50) (e.g., a phase current of the motor (50)), if insulation deterioration of the motor (50) occurs, a frequency component corresponding to three times the fundamental frequency of the first signal tends to increase. Therefore, when the first signal is an AC signal related to the motor (50), by setting the frequency of the first frequency component (C1) to "three times the fundamental frequency of the first signal," it is possible to estimate "insulation deterioration of the motor (50)."

[0161] [3. Bearing wear] Bearing wear is a state (abnormality) in which the rotating shaft rotated by the motor (50) or the bearing of the rotating shaft wears out.

[0162] When the first signal is a DC signal, the occurrence of bearing wear tends to increase frequency components that correspond to 1 / 3 and 2 / 3 times the rotation frequency of the motor (50). Therefore, when the first signal is a DC signal, the "bearing wear" can be estimated by setting the frequency of the first frequency component (C1) to "at least one of 1 / 3 and 2 / 3 times the rotation frequency of the motor (50)."

[0163] Furthermore, when the first signal is an AC signal, bearing wear tends to increase in the following frequency components when bearing wear occurs: a frequency component corresponding to the frequency obtained by adding "1 / 3 times the rotation frequency of the motor (50)" to the fundamental frequency of the first signal; a frequency component corresponding to the frequency obtained by subtracting "1 / 3 times the rotation frequency of the motor (50)" from the fundamental frequency of the first signal; a frequency component corresponding to the frequency obtained by adding "2 / 3 times the rotation frequency of the motor (50)" to the fundamental frequency of the first signal; and a frequency component corresponding to the frequency obtained by subtracting "2 / 3 times the rotation frequency of the motor (50)" from the fundamental frequency of the first signal. Therefore, when the first signal is an AC signal, the "bearing wear" can be estimated by setting the frequency of the first frequency component (C1) to a frequency obtained by adding "1 / 3 times the rotation frequency of the motor (50)" to the fundamental frequency of the first signal, a frequency obtained by subtracting "1 / 3 times the rotation frequency of the motor (50)" from the fundamental frequency of the first signal, a frequency obtained by adding "2 / 3 times the rotation frequency of the motor (50)" to the fundamental frequency of the first signal, or a frequency obtained by subtracting "2 / 3 times the rotation frequency of the motor (50)" from the fundamental frequency of the first signal.

[0164] [4. Dilution] Dilution is a state (abnormality) that can occur when the motor (50) is a "motor (50) mounted on a compressor," and is a state in which the oil concentration in the compressor is insufficient. When dilution occurs, friction at bearings (not shown) in the compressor increases, leading to wear of the bearings. Furthermore, when dilution occurs, the sliding parts (not shown) in the compressor run out of lubricating oil, causing friction and leading to surface roughness of the sliding parts.

[0165] When the first signal is a DC signal, the occurrence of dilution tends to decrease the frequency component corresponding to one time the rotation frequency of the motor (50). Therefore, when the first signal is a DC signal, the "dilution" can be estimated by setting the frequency of the first frequency component (C1) to "one time the rotation frequency of the motor (50)."

[0166] Furthermore, when the first signal is an AC signal, if dilution occurs, the frequency component corresponding to the frequency obtained by adding "one times the rotation frequency of the motor (50)" to the fundamental frequency of the first signal and the frequency component corresponding to the frequency obtained by subtracting "one times the rotation frequency of the motor (50)" from the fundamental frequency of the first signal tend to decrease. Therefore, when the first signal is an AC signal, "dilution" can be estimated by setting the frequency of the first frequency component (C1) to the frequency obtained by adding "one times the rotation frequency of the motor (50)" to the fundamental frequency of the first signal, or the frequency obtained by subtracting "one times the rotation frequency of the motor (50)" from the fundamental frequency of the first signal.

[0167] [5. Liquid Compression] Liquid compression is a state (abnormality) that can occur when the motor (50) is a "motor (50) mounted on a compressor," in which a liquid fluid is sucked into a compression chamber (not shown) of the compressor. The occurrence of liquid compression can lead to metal fatigue or damage to components that constitute the compression chamber.

[0168] When the first signal is a DC signal, the occurrence of liquid compression tends to increase the frequency component corresponding to one time the rotation frequency of the motor (50). Therefore, when the first signal is a DC signal, the "liquid compression" can be estimated by setting the frequency of the first frequency component (C1) to "one time the rotation frequency of the motor (50)."

[0169] Furthermore, when the first signal is an AC signal, when liquid compression occurs, there is a tendency for a frequency component corresponding to a frequency obtained by adding "one times the rotation frequency of the motor (50)" to the fundamental frequency of the first signal, and a frequency component corresponding to a frequency obtained by subtracting "one times the rotation frequency of the motor (50)" from the fundamental frequency of the first signal, to increase. Therefore, when the first signal is an AC signal, "liquid compression" can be estimated by setting the frequency of the first frequency component (C1) to a frequency obtained by adding "one times the rotation frequency of the motor (50)" to the fundamental frequency of the first signal, or to a frequency obtained by subtracting "one times the rotation frequency of the motor (50)" from the fundamental frequency of the first signal.

[0170] [6. Imbalance] The imbalance is a state (abnormality) that can occur when the motor (50) is a "motor (50) that drives the blades of a fan," and is a state in which imbalance occurs among the multiple blades provided in the fan. For example, the imbalance occurs due to different degrees of deformation, damage, dirt, and frost on each of the multiple blades.

[0171] When the first signal is an AC signal related to the motor 50 (e.g., a phase current of the motor 50), if an imbalance occurs, there is a tendency for a frequency component corresponding to a frequency obtained by adding "one times the rotation frequency of the motor 50" to the fundamental frequency of the first signal and a frequency component corresponding to a frequency obtained by subtracting "one times the rotation frequency of the motor 50" from the fundamental frequency of the first signal to increase. Therefore, when the first signal is an AC signal related to the motor 50, the "imbalance" can be estimated by setting the frequency of the first frequency component C1 to a frequency obtained by adding "one times the rotation frequency of the motor 50" to the fundamental frequency of the first signal or a frequency obtained by subtracting "one times the rotation frequency of the motor 50" from the fundamental frequency of the first signal.

[0172] [7. Flow path blockage] The blockage of the flow path is a state (abnormality) that can occur when the motor (50) is a "motor (50) that drives the blades of a fan," and is a state in which the flow path in which the fan is installed is blocked. The blockage of the flow path occurs, for example, when a filter (not shown) installed in the flow path together with the fan becomes clogged. When the blockage of the flow path occurs, a load fluctuation due to turbulence causes a disturbance in the reaction force during air blowing, resulting in a change in speed.

[0173] When the first signal is a DC signal, if a blockage of the flow path occurs, the frequency component having a peak near one time the rotation frequency of the motor (50) tends to fluctuate. Therefore, when the first signal is a DC signal, by setting the frequency of the first frequency component (C1) to one time the rotation frequency of the motor (50), it is possible to estimate the "blockage of the flow path."

[0174] Furthermore, when the first signal is an AC signal related to the motor (50) (e.g., a phase current of the motor (50)), the fundamental frequency of the first signal tends to fluctuate when a blockage of the flow path occurs. Therefore, when the first signal is an AC signal related to the motor (50), the "blockage of the flow path" can be estimated by setting the frequency of the first frequency component (C1) to the fundamental frequency of the first signal.

[0175] (Specific example of estimation process) Next, a specific example of the estimation process will be described. In the estimation process, the control unit (31) estimates the state of the device (70) based on a result of comparing a variable calculated based on the amplitude of the first frequency component (C1) with a predetermined threshold. Hereinafter, the variable calculated based on the amplitude of the first frequency component (C1) will be referred to as a "first variable."

[0176] Examples of the first variable include the instantaneous value of the amplitude of the first frequency component (C1), the rate of change of the amplitude of the first frequency component (C1), the cumulative time obtained by accumulating the time during which the amplitude of the first frequency component (C1) is equal to or greater than an upper limit value, and the proportion of the time during which the first frequency component (C1) is equal to or greater than a predetermined upper limit value within a predetermined judgment time.

[0177] Specifically, examples of the estimation process include the following four estimation processes (first to fourth estimation processes). Note that in the following description, the "first frequency component (C1)" refers to the "amplitude of the first frequency component (C1)."

[0178] [First estimation process] First, the first estimation process will be described with reference to Fig. 10. In the first estimation process, the control unit (31) estimates whether the state of the device (70) is abnormal or not, based on the instantaneous value of the first frequency component (C1). Specifically, the control unit (31) performs the following processes (steps (S11) to (S13)) for each predetermined detection period. The instantaneous value of the first frequency component (C1) is an example of a first variable.

[0179] <Step (S11)> The control unit (31) acquires the instantaneous value of the first frequency component (C1).

[0180] <Step (S12)> Next, the control unit (31) determines whether the instantaneous value of the first frequency component (C1) acquired in step (S11) is equal to or greater than a predetermined upper limit value. Note that this upper limit value is an example of a threshold value used in the estimation process. If the instantaneous value of the first frequency component (C1) is equal to or greater than the upper limit value, the control unit (31) performs the process of step (S13). On the other hand, if not, the control unit (31) performs the process of step (S14).

[0181] <Step (S13)> If the instantaneous value of the first frequency component (C1) is equal to or greater than the upper limit in step (S12), the control unit (31) estimates that the state of the device (70) is abnormal, and outputs an estimation result indicating that the state of the device (70) is abnormal.

[0182] <Step (S14)> On the other hand, if the instantaneous value of the first frequency component (C1) is not equal to or greater than the upper limit value in step (S12), the control unit (31) estimates that the state of the device (70) is normal, and outputs an estimation result indicating that the state of the device (70) is normal.

[0183] [Second estimation process] The second estimation process will be described with reference to Fig. 11 and Fig. 12. In the second estimation process, the control unit (31) estimates whether the state of the device (70) is abnormal or not, based on the rate of change of the first frequency component (C1). Specifically, the control unit (31) repeatedly performs the following processes (steps (S21) to (S23)) for each predetermined detection period. The rate of change of the first frequency component (C1) is an example of a first variable.

[0184] <Step (S21)> The control unit 31 acquires the rate of change of the first frequency component C1. For example, the control unit 31 derives the rate of change of the first frequency component C1 by differentiating the instantaneous value of the first frequency component C1 with respect to time. In the example of Fig. 12, the rate of change of the first frequency component C1 changes at each of times t1, t2, and t3.

[0185] <Step (S22)> The control unit (31) determines whether the rate of change of the first frequency component (C1) acquired in step (S21) is equal to or greater than a predetermined upper limit. Note that this upper limit is an example of a threshold used in the estimation process. If the rate of change of the first frequency component (C1) is equal to or greater than the upper limit, the process of step (S23) is performed. On the other hand, if not, the process of step (S24) is performed. In the example of FIG. 12, the rate of change of the first frequency component (C1) is equal to or greater than the upper limit at time (t2).

[0186] <Step (S23)> If the rate of change of the first frequency component (C1) is equal to or greater than the upper limit in step (S22), the control unit (31) estimates that the state of the device (70) is abnormal, and outputs an estimation result indicating that the state of the device (70) is abnormal.

[0187] <Step (S24)> On the other hand, if the rate of change of the first frequency component (C1) is not equal to or greater than the upper limit in step (S22), the control unit (31) estimates that the state of the device (70) is normal, and outputs an estimation result indicating that the state of the device (70) is normal.

[0188] [Third estimation process] The third estimation process will be described with reference to Fig. 13 and Fig. 14. In the third estimation process, the control unit (31) estimates whether the state of the device (70) is abnormal based on the accumulated time obtained by accumulating the time during which the first frequency component (C1) is equal to or greater than the upper limit. Specifically, the control unit (31) repeatedly performs the following process (steps (S31) to (S33)) for each predetermined detection period. The accumulated time obtained by accumulating the time during which the first frequency component (C1) is equal to or greater than the upper limit is an example of a first variable.

[0189] <Step (S31)> The control unit 31 acquires the cumulative value (cumulative time) of the time during which the first frequency component C1 is equal to or greater than the upper limit value. Note that this upper limit value is an example of a threshold value used in the estimation process.

[0190] For example, the control unit (31) acquires an instantaneous value of the first frequency component (C1) that is a representative value in the detection cycle, and determines whether the instantaneous value of the first frequency component (C1) is equal to or greater than an upper limit. If the instantaneous value of the first frequency component (C1) is equal to or greater than the upper limit, the control unit (31) increments the count value. If the instantaneous value of the first frequency component (C1) is not equal to or greater than the upper limit, the control unit (31) does not increment the count value. This count value corresponds to the cumulative value (cumulative time) of the time during which the first frequency component (C1) is equal to or greater than the upper limit. For example, the cumulative time is the value obtained by multiplying the count value by the time corresponding to the detection cycle.

[0191] In the example of FIG. 14, the third estimation process is performed at each of the times (t1 to t12), and the count value is incremented at times (t2 to t5, t9 to t12) among the times (t1 to t12).

[0192] <Step (S32)> Next, the control unit (31) determines whether the cumulative time (count value in this example) acquired in step (S31) is equal to or greater than a predetermined threshold. This threshold is an example of a threshold used in the estimation process. If the cumulative time is equal to or greater than the threshold, the process of step (S33) is performed, whereas if not, the process of step (S34) is performed. In the example of FIG. 14, the control unit (31) determines that the count value exceeds the threshold at time (t11).

[0193] <Step (S33)> If the cumulative time is equal to or greater than the threshold value in step S32, the control unit 31 estimates that the state of the device 70 is abnormal, and outputs an estimation result indicating that the state of the device 70 is abnormal.

[0194] <Step (S34)> On the other hand, if the cumulative time is not equal to or greater than the threshold in step S32, the control unit 31 estimates that the state of the device 70 is normal, and outputs an estimation result indicating that the state of the device 70 is normal.

[0195] [Fourth estimation process] The fourth estimation process will be described with reference to Fig. 15 and Fig. 16. In the fourth estimation process, the control unit (31) estimates whether the state of the device (70) is abnormal based on the proportion (time proportion) of the time during which the first frequency component (C1) is equal to or greater than a predetermined upper limit within a predetermined determination time. Specifically, the control unit (31) repeatedly performs the following processes (steps (S41) to (S43)) for each predetermined detection period. Note that the proportion (time proportion) of the time during which the first frequency component (C1) is equal to or greater than a predetermined upper limit within the predetermined determination time is an example of a first variable.

[0196] <Step (S41)> The control unit 31 acquires the proportion (time proportion) of the time during which the first frequency component C1 is equal to or greater than the upper limit value within the determination time. Note that this upper limit value is an example of a threshold value used in the estimation process.

[0197] For example, the control unit (31) stores the first frequency component (C1) within a determination period (a period equivalent to at least the determination time) ending at the current time. Then, based on the stored first frequency component (C1), the control unit (31) derives the time during which the first frequency component (C1) is equal to or greater than the upper limit value (the time exceeding the upper limit) within the determination period ending at the current time and having a length equivalent to the determination time, and derives the time ratio by dividing the time exceeding the upper limit by the determination time. In the example of Fig. 16, time (t2) is the current time, the period from time (t1) to time (t2) is the determination period, times (T1) and (T2) are the time exceeding the upper limit, and the value obtained by dividing the sum of time (T1) and time (T2) by the determination time (T0) is the time ratio.

[0198] <Step (S42)> Next, the control unit (31) determines whether the time ratio acquired in step (S41) (the ratio of the time during which the first frequency component (C1) is equal to or greater than the upper limit value within the determination time) is equal to or greater than a predetermined threshold. This threshold is an example of a threshold used in the estimation process. If the time ratio is equal to or greater than the threshold, the process of step (S43) is performed. On the other hand, if not, the process of step (S44) is performed.

[0199] <Step (S43)> If the time ratio is equal to or greater than the threshold value in step S42, the control unit 31 estimates that the state of the device 70 is abnormal, and outputs an estimation result indicating that the state of the device 70 is abnormal.

[0200] <Step (S44)> On the other hand, if the time ratio is not equal to or greater than the threshold value in step S42, the control unit 31 estimates that the state of the device 70 is normal, and outputs an estimation result indicating that the state of the device 70 is normal.

[0201] In the above description of the estimation process, the first variable is compared with an upper limit value (or threshold value), but the present invention is not limited to this. For example, the first variable may be compared with a predetermined lower limit value. That is, the above phrase "above or below the upper limit value (or threshold value)" may be read as "below or below the lower limit value (or threshold value)." The first variable may also be compared with a predetermined allowable range. That is, the above phrase "above or below the upper limit value (or threshold value)" may be read as "outside the allowable range."

[0202] [Specific example of restriction processing (restriction determination processing)] Next, a specific example of the restriction determination process (step (S101) in FIG. 9) included in the restriction process will be described. The restriction determination process is a process for determining whether or not a restriction execution condition based on the second frequency component (C2) is established.

[0203] In this example, in the restriction determination process, the control unit (31) determines whether or not a restriction execution condition based on the second frequency component (C2) is satisfied based on a result of comparison between a variable calculated based on the amplitude of the second frequency component (C2) and a predetermined threshold. Hereinafter, the variable calculated based on the amplitude of the second frequency component (C2) will be referred to as a “second variable.”

[0204] In this example, the restriction execution condition based on the second frequency component (C2) is that the second variable is equal to or greater than a threshold value. When the control unit (31) determines in the restriction determination process (step (S101)) that the second variable is equal to or greater than the threshold value, the control unit (31) performs the restriction execution process (step (S102)).

[0205] Examples of the second variable include the instantaneous value of the amplitude of the second frequency component (C2), the rate of change of the amplitude of the second frequency component (C2), the cumulative time obtained by accumulating the time during which the amplitude of the second frequency component (C2) is equal to or greater than an upper limit value, and the proportion of the time during which the second frequency component (C2) is equal to or greater than a predetermined upper limit value within a predetermined judgment time.

[0206] Specifically, examples of the restriction determination process include the following four restriction determination processes (first to fourth restriction determination processes). Note that in the following description, the "second frequency component (C2)" refers to the "amplitude of the second frequency component (C2)."

[0207] [First restriction determination process] In the first restriction determination process, the control unit (31) determines whether or not the restriction execution condition is satisfied based on the instantaneous value of the second frequency component (C2). Specifically, the control unit (31) determines that the restriction execution condition is satisfied when the instantaneous value of the second frequency component (C2) is equal to or greater than a predetermined upper limit value. Note that the instantaneous value of the second frequency component (C2) is an example of a second variable, and the upper limit value is an example of a threshold value used in the restriction determination process.

[0208] [Second restriction determination process] In the second restriction determination process, the control unit (31) determines whether or not the restriction execution condition is satisfied based on the rate of change of the second frequency component (C2). Specifically, the control unit (31) determines that the restriction execution condition is satisfied when the rate of change of the second frequency component (C2) is equal to or greater than a predetermined upper limit value. Note that the rate of change of the second frequency component (C2) is an example of a second variable, and the upper limit value is an example of a threshold value used in the restriction determination process. The rate of change of the second frequency component (C2) is derived in the same manner as the rate of change of the first frequency component (C1) in the second estimation process.

[0209] [Third restriction determination process] In the third restriction determination process, the control unit (31) determines whether or not the restriction execution condition is satisfied based on the accumulated time obtained by accumulating the time during which the second frequency component (C2) is equal to or greater than the upper limit value. Specifically, the control unit (31) determines that the restriction execution condition is satisfied when the accumulated time is equal to or greater than a predetermined threshold value. Note that the accumulated time is an example of a second variable, and the threshold value is an example of a threshold value used in the restriction determination process. The derivation of the accumulated time is similar to the derivation of the "accumulated time obtained by accumulating the time during which the first frequency component (C1) is equal to or greater than the upper limit value" in the third estimation process.

[0210] [Fourth restriction determination process] In the fourth restriction determination process, the control unit (31) determines whether or not the restriction execution condition is satisfied based on the proportion (time proportion) of the time during which the second frequency component (C2) is equal to or greater than a predetermined upper limit value within a predetermined determination time. Specifically, the control unit (31) determines that the restriction execution condition is satisfied when the time proportion is equal to or greater than a predetermined threshold. Note that the time proportion is an example of a second variable, and the threshold is an example of a threshold used in the restriction determination process. The derivation of the time proportion is similar to the derivation of "the proportion of the time during which the first frequency component (C1) is equal to or greater than a predetermined upper limit value within a predetermined determination time" in the fourth estimation process.

[0211] In the above description of the restriction execution process, the second variable is compared with an upper limit value (or threshold value), but the present invention is not limited to this. For example, the second variable may be compared with a predetermined lower limit value. In other words, the above phrase "above or below the upper limit value (or threshold value)" may be read as "below or below the lower limit value (or threshold value)." The second variable may also be compared with a predetermined allowable range. In other words, the above phrase "above or below the upper limit value (or threshold value)" may be read as "outside the allowable range."

[0212] [Specific examples of restriction processing (restriction execution processing)] Next, a specific example of the restriction execution process (step (S102) in FIG. 9) included in the restriction process will be described. The restriction execution process is a process for restricting the estimation process or the operation of the motor (50) so as to prevent erroneous estimation in the estimation process.

[0213] The restriction execution process includes an estimation restriction process that restricts the estimation process to prevent erroneous estimation, and an operation restriction process that restricts the operation of the motor (50) to prevent erroneous estimation. Examples of the estimation restriction process include the following five estimation restriction processes (first to fifth estimation restriction processes).

[0214] [First presumption restriction process] First, the first estimation restriction process will be described. The first estimation restriction process is a process for prohibiting (stopping) the execution of the estimation process. In the first estimation restriction process, the control unit (31) stops the estimation process and outputs a predetermined estimation result. This directly restricts the estimation process so that the predetermined estimation result is output. In this way, it is possible to prevent an erroneous estimation result from being obtained, thereby suppressing erroneous estimation of the state of the device (70).

[0215] In this example (an example in which the presence or absence of an abnormality in the device 70 is estimated in the estimation process), the “predetermined estimation result” is an estimation result that does not indicate that the device 70 is abnormal. Examples of the predetermined estimation result include an estimation result that indicates that the device 70 is normal, an estimation result that indicates that the state of the device 70 is unknown, an estimation result that indicates that the estimation process is prohibited (stopped), an estimation result that was output before (for example, immediately before) the estimation process was restricted, etc.

[0216] [Second presumption restriction process] Next, the second estimation restriction process will be described. The second estimation restriction process is a process for correcting an estimation result obtained by the estimation process. In the second estimation restriction process, the control unit (31) continues the estimation process while correcting the estimation result obtained by the estimation process to a "predetermined estimation result." This directly restricts the estimation process so that the predetermined estimation result is output. In this way, it is possible to prevent an erroneous estimation result from being obtained, thereby suppressing erroneous estimation of the state of the device (70).

[0217] [Third Presumption Restriction Processing] Next, the third estimation restriction process will be described. The third estimation restriction process is a process for prohibiting (stopping) the execution of the calculation process. In the third estimation restriction process, the control unit (31) stops the calculation process and sets a variable used in the estimation process (a variable calculated based on the amplitude of the first frequency component (C1)) to a "predetermined variable" so that a predetermined estimation result is obtained in the estimation process. This indirectly restricts the estimation process so that a predetermined estimation result is output. In this way, it is possible to prevent an erroneous estimation result from being obtained, thereby suppressing erroneous estimation of the state of the device (70).

[0218] [Fourth Presumption Restriction Processing] Next, the fourth estimation restriction process will be described. The fourth estimation restriction process is a process for correcting the first frequency component (C1) calculated by the calculation process. In the fourth estimation restriction process, the control unit (31) continues the calculation process, while correcting the first frequency component (C1) calculated by the calculation process to a "predetermined first frequency component (C1)" so that a predetermined estimation result is obtained in the estimation process. This indirectly restricts the estimation process so that a predetermined estimation result is output. In this way, it is possible to prevent an erroneous estimation result from being obtained, thereby suppressing erroneous estimation of the state of the device (70).

[0219] [5th ​​Presumption Restriction Processing] Next, the fifth estimation restriction process will be described. The fifth estimation restriction process is a process performed when the control unit (31) estimates the state of the device (70) based on a result of comparison between a variable (a variable calculated based on the amplitude of the first frequency component (C1)) and a predetermined threshold in the estimation process, and is a process of correcting at least one of the variable and the threshold. In the fifth estimation restriction process, the control unit (31) corrects the threshold used in the estimation process to a "predetermined threshold" so that a predetermined estimation result is obtained in the estimation process. Alternatively, in the fifth estimation restriction process, the control unit (31) corrects the variable used in the estimation process to a "predetermined variable" so that a predetermined estimation result is obtained in the estimation process. This directly restricts the estimation process so that a predetermined estimation result is output. In this way, it is possible to prevent an erroneous estimation result from being obtained, thereby suppressing erroneous estimation of the state of the device (70).

[0220] [Operation restriction processing] Next, the operation restriction process will be described. In this example, the operation restriction process is a process of changing the operating conditions of the motor (50) so as to prevent erroneous estimation in the estimation process. The process of changing the operating conditions of the motor (50) is a process of changing the rotation frequency of the motor (50). In the operation restriction process, the control unit (31) changes the operating conditions of the motor (50), including the rotation frequency of the motor (50), so as to prevent erroneous estimation in the estimation process.

[0221] In this way, by changing the operating conditions of the motor (50) (in this example, the rotational frequency of the motor (50)), it is possible to prevent the first frequency component (C1) included in the first signal correlated with the state of the device (70) from being affected by amplitude fluctuations in the DC voltage. This makes it possible to suppress amplitude fluctuations (unintended amplitude fluctuations) in the first frequency component (C1) caused by amplitude fluctuations in the DC voltage, thereby suppressing erroneous estimation of the state of the device (70).

[0222] (Refrigeration system) 17 illustrates the configuration of a refrigeration system (RR). The refrigeration system (RR) includes a refrigerant circuit (RR1) filled with a refrigerant, a motor drive device (20), and a control device (30). The motor drive device (20) and the control device (30) illustrated in FIG. 27 are the motor drive device (20) and the control device (30) illustrated in FIG. 1.

[0223] The refrigerant circuit (RR1) includes a compressor (CC), a radiator (RR5), a pressure reduction mechanism (RR6), and an evaporator (RR7). In this example, the pressure reduction mechanism (RR6) is an expansion valve. The refrigerant circuit (RR1) performs a vapor compression refrigeration cycle.

[0224] The compressor (CC) has a compression mechanism (CCa) and a motor (50). The compression mechanism (CCa) is connected to the motor (50) by a rotary shaft. The motor (50) rotationally drives the compression mechanism (CCa) by driving the rotary shaft. The motor drive device (20) drives the motor (50). The control device (30) determines the state of the refrigeration system (RR) equipped with the compressor (CC) having the motor (50).

[0225] In the refrigeration cycle, the refrigerant discharged from the compressor (CC) dissipates heat in the radiator (RR5). The refrigerant flowing out from the radiator (RR5) is decompressed in the pressure reducing mechanism (RR6) and evaporated in the evaporator (RR7). The refrigerant flowing out from the evaporator (RR7) is then drawn into the compressor (CC).

[0226] In this example, the refrigeration system (RR) is an air conditioner. The air conditioner may be a dedicated cooling unit or a dedicated heating unit. The air conditioner may also be an air conditioner that switches between cooling and heating. In this case, the air conditioner has a switching mechanism (e.g., a four-way switching valve) that switches the refrigerant circulation direction. The refrigeration system (RR) may also be a water heater, a chiller unit, a cooling device that cools the air inside a storage unit, etc. The cooling device cools the air inside a refrigerator, freezer, container, etc.

[0227] (Fan system) 18 illustrates the configuration of a fan system (FF). The fan system (FF) includes a fan (FF1), a motor drive device (20), and a control device (30). The motor drive device (20) and the control device (30) illustrated in FIG. 28 are the motor drive device (20) and the control device (30) illustrated in FIG. 1.

[0228] The fan (FF1) is provided in a flow path (not shown) through which a fluid (e.g., a gas such as air) flows. The fan (FF1) has a rotor (FFa) having blades and a motor (50). The rotor (FFa) is connected to the motor (50) by a rotary shaft. The motor (50) drives the rotor (FFa) by driving the rotary shaft to rotate. A motor drive device (20) drives the motor (50). A control device (30) estimates the state of the fan system (FF) equipped with the motor (50). The state of the fan system (FF) estimated by the control device (30) includes blockage of the flow path in which the fan (FF1) is provided (a state in which the flow path is blocked).

[0229] (Pump system) 19 illustrates the configuration of a pump system (PP). The pump system (PP) includes a pump (PP1), a motor drive device (20), and a control device (30). The motor drive device (20) and the control device (30) illustrated in FIG. 19 are the motor drive device (20) and the control device (30) illustrated in FIG. 1.

[0230] The pump (PP1) is provided in a flow path (not shown) through which a fluid (e.g., a liquid such as water) flows. The pump (PP1) is connected to a motor (50) by a rotating shaft. The motor (50) rotates the pump (PP1) by driving the rotating shaft. The motor drive device (20) drives the motor (50). The control device (30) estimates the state of the pump system (PP) in which the motor (50) is mounted.

[0231] (Other embodiments) In the above description, the state of the device (70) may refer to the state of the device (70) as a whole, or may refer to the state of some of the elements included in the device (70). For example, if the device (70) is an "outdoor unit equipped with a compressor (CC) having a motor (50)," the state of the device (70) may refer to the state of the outdoor unit, the state of the compressor (CC), the state of the motor (50), or the state of other elements of the outdoor unit.

[0232] Furthermore, in the above description, the estimation process is performed to estimate whether or not there is an abnormality in the device (70), but the present invention is not limited to this.

[0233] For example, in the estimation process, the control unit (31) may estimate the degree of wear of a rotating shaft (not shown) rotated by the motor (50) or a bearing (not shown) of the rotating shaft. In this case, the control unit (31) may estimate the degree of wear according to the first frequency component (C1) obtained by the calculation process such that the degree of wear of the rotating shaft or the bearing increases as the first frequency component (C1) obtained by the calculation process increases. Examples of the "predetermined estimation result" output when the estimation process for estimating the degree of wear is restricted include an estimation result indicating that the degree of wear of the device (70) is unknown, an estimation result indicating that the estimation process is prohibited (stopped), etc.

[0234] Furthermore, the control unit (31) may estimate the remaining life of the motor (50) in the estimation process. In this case, the control unit (31) may estimate the remaining life in accordance with the feature amount obtained by the calculation process such that the larger the feature amount obtained by the calculation process, the shorter the remaining life of the motor (50). Examples of the "predetermined estimation result" output when the estimation process for estimating the remaining life is restricted include an estimation result indicating that the remaining life of the device (70) is unknown, an estimation result indicating that the estimation process is prohibited (stopped), etc.

[0235] In the above description, a bandpass filter that extracts a signal in a frequency band including the frequency of the first frequency component (C1) may be used in the calculation process. Also, a bandpass filter process that extracts a signal in a frequency band including the frequency of the first frequency component (C1) may be performed in the calculation process.

[0236] In the above description, various filters such as a Kalman filter may be used to extract the periodic component contained in the first frequency component (C1). Furthermore, various frequency analysis processes such as wavelet analysis may be used to extract the periodic component contained in the first frequency component (C1). The same applies to the calculation (extraction) of the first frequency component (C1).

[0237] In the above description, the first variable (a variable calculated based on the amplitude of the first frequency component (C1)) may be an instantaneous value of the first frequency component (C1), the square root of the sum of the squares of the first frequency component (C1), the rate of change of the first frequency component (C1), the ratio of the short-term moving average to the long-term moving average of the first frequency component (C1), addition, subtraction, multiplication, or division of a plurality of first frequency components (C1), a power of the first frequency component (C1), or a combination of at least two of these. The estimation process may also be performed based on such a first variable. The estimation process may also be performed based on the duration during which such a first variable exceeds a threshold value, the number of times such a first variable exceeds a threshold value, or the like. The estimation process may also be performed based on a combination of the first frequency component (C1) and another characteristic frequency component (e.g., a frequency component corresponding to an integer multiple of the rotation frequency of the motor (50)). The same applies to the second variable calculated based on the amplitude of the second frequency component (C2).

[0238] The ratio of the short-term moving average to the long-term moving average of the first frequency component (C1) may be a value obtained by dividing the short-term moving average value of the first frequency component (C1) by the long-term moving average value. The short-term moving average value is the moving average value of the first frequency component (C1) within a first time period. The long-term moving average value is the moving average value of the first frequency component (C1) within a second time period. The second time period is longer than the first time period.

[0239] In the above description, the first frequency component (C1) may be a frequency component corresponding to a single frequency, or may be a frequency component corresponding to a frequency range based on the single frequency. The same applies to the second frequency component (C2).

[0240] Furthermore, in the above description, when the first signal is an AC signal, the estimation process may be performed based on either one of two first frequency components (C1) that are symmetrical about the fundamental frequency of the first signal, or the estimation process may be performed based on both of the two first frequency components (C1).

[0241] In the above description, the first signal may be a measured value, a command value, or an estimated value.

[0242] In addition, in the above description, the control unit (31) may be configured to perform the estimation process using an algorithm (an algorithm for determining a state based on a change in a signal) constructed by a neural network or machine learning.

[0243] In the above description, the control unit 31 may be realized by one processor or by multiple processors. The control unit 31 may also be realized by multiple arithmetic processing units (computers) that communicate with each other via a communication network.

[0244] Although the above description has been given of an example in which the power supply (60) is a three-phase AC power supply, the power supply (60) is not limited to this and may be, for example, a single-phase AC power supply.

[0245] Although the DC unit (22) includes a capacitor in the above description, the present invention is not limited to this. For example, the DC unit (22) may be an LC circuit including a capacitor and a reactor. This configuration can prevent noise currents caused by switching operations of the switching elements of the inverter (23) from flowing into the power supply (60).

[0246] The capacitance value of the capacitor may be set to a value that can barely smooth the output of the converter (21) but can smooth ripples generated by the switching operation of the inverter (23). Such a capacitor has a relatively small capacitance and does not absorb voltage fluctuations from the converter (21), but absorbs voltage fluctuations caused by the switching operation of the inverter (23). Specifically, the capacitor may be a small-capacity capacitor having a capacitance value approximately 1 / 100 of the capacitance of a smoothing capacitor (e.g., an electrolytic capacitor) used to smooth the output of the converter (21) in a typical power conversion device. The DC voltage generated by the DC section (22) having such a capacitor contains residual pulsating components corresponding to the frequency of the power supply voltage.

[0247] For example, when the power supply (60) is a three-phase AC power supply, the capacitance value of the capacitor of the DC unit (22) may be set to a value disclosed in, for example, Japanese Patent Application Laid-Open No. 2019-88088 or No. 2019-88090. When the power supply (60) is a single-phase AC power supply, the capacitance value of the capacitor of the DC unit (22) may be set so that the maximum value of the pulsating DC voltage is at least twice the minimum value of the DC voltage.

[0248] In addition, when the capacitor of the DC unit 22 is a small-capacity capacitor, amplitude fluctuations are more likely to occur in the DC voltage generated by the DC unit 22 than when the capacitor of the DC unit 22 is a smoothing capacitor, so it is important to consider the influence of amplitude fluctuations of the DC voltage. For example, when the capacitor of the DC unit 22 is a small-capacity capacitor, voltage distortion is more likely to propagate from the power supply 60 to the DC unit 22. Therefore, when a diagnosis based on the frequency component of the motor current (diagnosis of a state such as an abnormality in the device) such as MCSA is performed, the distortion may lead to an erroneous diagnosis.

[0249] Therefore, when the capacitor of the DC section (22) is a small-capacity capacitor, the above-described limiting process (a process of limiting the estimation process or the operation of the motor (50) based on the second frequency component (C2) contained in the DC voltage to prevent erroneous estimation in the estimation process) is particularly effective.

[0250] Although the embodiments and modifications have been described, it will be understood that various changes in form and details are possible without departing from the spirit and scope of the claims. Furthermore, elements of the above-described embodiments, modifications, and other embodiments may be combined or substituted as appropriate. [Industrial Applicability]

[0251] As described above, the present disclosure is useful as a state estimation technique. [Explanation of symbols]

[0252] 10 Drive System 20 Motor drive unit 21 Converter 22 DC section 23 Inverter 30 Control device (state estimation device) 31 Control Unit 41 Phase current detection unit 42 Rotational frequency detector 50 motor 60 power supply 70 equipment CC Compressor RR Refrigeration System RR1 refrigerant circuit FF Fan System FF1 fan PP Pump System PP1 Pump

Claims

1. A state estimation device for estimating a state of equipment (70) equipped with a motor (50) driven by a motor drive device (20) including a DC section (22) that generates a DC voltage corresponding to a power supply voltage supplied from a power supply (60) and a conversion section (23) that converts the DC voltage generated by the DC section (22) into an AC voltage by a switching operation, A control unit (31) is provided, The control section (31) an estimation process of estimating a state of the device (70) based on a first frequency component (C1) among frequency components included in a first signal, which is not a signal indicating the DC voltage but a signal correlated with a state of the device (70); performing a limiting process for limiting the estimation process or the operation of the motor (50) to prevent erroneous estimation from occurring in the estimation process, based on a second frequency component (C2) excluding an integer multiple of the frequency of the power supply voltage from among frequency components included in the DC voltage; The amplitude fluctuation of the second frequency component (C2) is correlated with the amplitude fluctuation of the first frequency component (C1). State estimator.

2. 2. The state estimating device of claim 1, the first signal is a DC signal; The frequency of the second frequency component (C2) is the same as the frequency of the first frequency component (C1). State estimator.

3. 2. The state estimating device of claim 1, the first signal is an AC signal, the frequency of the first frequency component (C1) is a frequency obtained by subtracting a specific frequency from the fundamental frequency of the first signal, or a frequency obtained by adding the specific frequency to the fundamental frequency of the first signal, The frequency of the second frequency component (C2) is the specific frequency. State estimator.

4. 2. The state estimating device of claim 1, The restriction process is a process of prohibiting the execution of the estimation process. State estimator.

5. 2. The state estimating device of claim 1, In the estimation process, the control unit (31) estimates the state of the device (70) based on a result of comparison between a variable calculated based on the amplitude of the first frequency component (C1) and a predetermined threshold value, The limiting process is a process of correcting at least one of the variables and the threshold value so that erroneous estimation is not performed in the estimation process. State estimator.

6. 2. The state estimating device of claim 1, the frequency of the first frequency component (C1) is set to a frequency according to the operating conditions of the motor (50); The limiting process is a process for changing the operating conditions of the motor (50) so that erroneous estimation does not occur in the estimation process. State estimator.

7. 7. The state estimating device of claim 6, the frequency of the first frequency component (C1) is set to a frequency corresponding to the rotation frequency of the motor (50); The process of changing the operating conditions of the motor (50) is a process of changing the rotation frequency of the motor (50). State estimator.

8. The state estimation device according to any one of claims 1 to 7, The device (70) is one of a compressor, a fan, and a pump. State estimator.

9. a motor drive device (20) that drives a motor (50) mounted on the equipment (70); a state estimating device that estimates a state of the equipment (70), The state estimation device is a state estimation device according to any one of claims 1 to 7. Drive system.

10. a refrigerant circuit (RR1) including a compressor (CC) having a motor (50); A refrigeration system comprising a state estimation device, The state estimation device is a state estimation device according to any one of claims 1 to 7, and estimates the state of the refrigeration system. Refrigeration system.

11. a fan (FF1) having a motor (50); A fan system including a state estimating device, The state estimating device is a state estimating device according to any one of claims 1 to 7, and estimates the state of the fan system. Fan system.

12. A state estimation method for estimating a state of an apparatus (70) including a motor (50) driven by a motor drive device (20) having a DC section (22) that generates a DC voltage corresponding to a power supply voltage supplied from a power supply (60) and a conversion section (23) that converts the DC voltage generated by the DC section (22) into an AC voltage by a switching operation, comprising: an estimation step of estimating a state of the device (70) based on a first frequency component (C1) among frequency components included in a first signal, which is not a signal indicating the DC voltage but is a signal correlated with a state of the device (70); a limiting step of limiting the estimation step or the operation of the motor (50) to prevent erroneous estimation from being made in the estimation step, based on a second frequency component (C2) that is not an integer multiple of the frequency of the power supply voltage among frequency components included in the DC voltage; The amplitude fluctuation of the second frequency component (C2) is correlated with the amplitude fluctuation of the first frequency component (C1). State estimation methods.

13. A state estimation program that causes a computer to execute the state estimation method of claim 12.

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