control device

Abstract

A control device is provided that can prevent the calculation accuracy of Fourier coefficients from being determined by the sampling frequency of an AD converter. [Solution] An AD converter 38 converts an analog signal into digital data at a sampling frequency required for synchronous PWM processing of a motor. The digital data output by the AD converter 38 is input to a DFT circuit 36. The DFT circuit 36 ​​includes a thinning circuit 54. The thinning circuit 54 thins out time-series data sampled at the sampling frequency and inputs the thinned data to an FFT 56. The FFT 56 uses the input data to calculate data related to Fourier coefficients.

Description

[Technical Field]

[0001] The present disclosure relates to a control device. [Background technology]

[0002] Patent Document 1 describes a control device that executes a process to correct a target value of a motor's rotation speed in accordance with frequency fluctuation components resulting from a Fourier transform of the motor's rotation speed. This process aims to suppress fluctuations in the motor's output torque.

[0003] On the other hand, synchronous PWM processing is well known as a method for controlling the control amount of a motor. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-127649 Summary of the Invention [Problem to be solved by the invention]

[0005] When performing synchronous PWM processing, it is necessary to sample the input data at a sampling frequency that is an integral multiple of the electrical angular frequency. On the other hand, if the input data used in the Fourier transform is matched to the sampling frequency of the synchronous PWM processing, the resolution is limited by the sampling frequency, and there is a risk that the desired resolution will not be achieved. [Means for solving the problem]

[0006] A control device according to a first aspect for solving the above-described problem is a control device for controlling a control amount of a control target, the control device comprising: a control circuit; an AD converter for converting an analog signal into digital data; a thinning circuit; and a Fourier transform circuit, wherein the control circuit is configured to execute a process for controlling the control amount based on first digital data, which is the digital data obtained by converting a predetermined analog signal by the AD converter; the Fourier transform circuit is configured to output coefficient data, which is data indicating Fourier coefficients, to the control circuit based on time series data of conversion data, the conversion data being second digital data, which is the digital data converted by the AD converter, or data calculated from the second digital data, and the second digital data being data synchronized with the first digital data; and the thinning circuit is a circuit for selecting the conversion data to be used in calculating the coefficient data by thinning out the time series data.

[0007] In the above configuration, the sampling frequency of the conversion data used to calculate the coefficient data can be changed relative to the sampling frequency of the AD converter by the thinning circuit thinning out the conversion data, thereby preventing the calculation accuracy of the coefficient data from being determined by the sampling frequency of the AD converter.

[0008] A control device according to a second aspect is the control device according to the first aspect, wherein a sampling frequency of the conversion data is equal to a sampling frequency of the first digital data input to the control circuit. In the above configuration, the conversion data sampled at a frequency equal to the sampling frequency of the digital data input to the control circuit is input to the thinning circuit, and by thinning out the conversion data, coefficient data can be calculated from the time series data of the conversion data sampled at a sampling frequency different from the sampling frequency of the digital data input to the control circuit.

[0009] A control device according to a third aspect is the control device according to the second aspect, wherein the controlled object is a rotating electric machine, and an output voltage of an inverter is applied to a terminal of the rotating electric machine, the AD converter is configured to convert the predetermined analog signal into the first digital data at a frequency that is an integer multiple of an electrical angular frequency of the rotating electric machine, and the control circuit is configured to perform synchronous PWM processing, which is a process of setting a switching pattern of the inverter based on the first digital data as an input variable each time the predetermined analog signal is converted into the first digital data at the integer multiple frequency.

[0010] In the above configuration, even though the conversion data is sampled at a sampling frequency equal to the sampling frequency defined by the synchronous PWM processing, the sampling frequency of the conversion data used to calculate the coefficient data can be changed by thinning out the conversion data.

[0011] A control device according to a fourth aspect is the control device according to any one of the first to third aspects, wherein the thinning circuit includes a first thinning circuit and a second thinning circuit, the Fourier transform circuit includes a first Fourier transform circuit and a second Fourier transform circuit, the first thinning circuit and the second thinning circuit have different intervals for thinning out the conversion data, the first Fourier transform circuit is configured to calculate the coefficient data using the conversion data thinned out by the first thinning circuit, and the second Fourier transform circuit is configured to calculate the coefficient data using the conversion data thinned out by the second thinning circuit.

[0012] In the above configuration, since the first and second thinning circuits are provided, the first and second Fourier transform circuits can calculate coefficient data based on conversion data sampled at different sampling frequencies. Therefore, even if the frequencies at which the coefficient data are to be calculated are different, the coefficient data can be calculated with high accuracy.

[0013] A control device according to a fifth aspect is the control device according to any one of the first to fourth aspects, wherein the Fourier transform circuit is configured to generate the coefficient data by fast Fourier transform. In the above configuration, by adopting a fast Fourier transform algorithm, it is possible to reduce the computation load on the Fourier transform circuit due to the calculation of coefficient data.

[0014] A control device of a sixth aspect is a control device according to any one of the first to fifth aspects, wherein the control circuit is configured to input frequency identification data, which is data for identifying a frequency for which a Fourier coefficient is to be calculated, to the Fourier transform circuit, and the thinning circuit is configured to select the conversion data to be used in calculating the coefficient data by thinning the conversion data in accordance with the frequency identification data.

[0015] In the above configuration, the Fourier transform circuit thins out the transform data in accordance with the frequency identification data, so that the ratio between the frequency for which a Fourier coefficient is to be obtained and the sampling frequency can be changed. A control device according to a seventh aspect is a control device according to any one of aspects 3 to 6 above (excluding those not including the matters of the third aspect), wherein the rotating electric machine is a motor that drives a compressor, and the output voltage of an inverter is applied to the terminals of the motor, the Fourier transform circuit is configured to calculate the coefficient data corresponding to a frequency that is a rational multiple of the mechanical angular frequency of the motor using the conversion data that has been thinned out by the thinning circuit, and the control circuit is configured to execute an output voltage adjustment process, and the output voltage adjustment process is configured to manipulate the output voltage of the inverter based on the coefficient data as an input variable.

[0016] The torque applied by the compressor to the motor varies depending on the compressor's rotation angle. Therefore, the load torque applied by the compressor to the motor is a rational multiple of the motor's mechanical angle. To evaluate the effect of this load torque, the amplitude of the fluctuation component at a frequency that is an integer multiple of the fluctuation period of the load torque applied by the compressor to the motor is useful information. However, using conversion data sampled at a sampling frequency determined by the requirements of synchronous PWM processing may result in inaccurate calculation of coefficient data corresponding to the frequency of the fluctuation component. Therefore, the above configuration thins out the conversion data, allowing coefficient data related to the Fourier coefficients of this fluctuation component to be calculated with the desired resolution. Then, by manipulating the inverter output voltage based on this coefficient data, torque fluctuations can be suppressed.

[0017] A control device of an eighth aspect is a control device according to any one of aspects 3 to 7 above (excluding those not including the matters of the third aspect), configured so that the output voltage of an inverter is applied to the terminals of the rotating electric machine, the Fourier transform circuit is configured to calculate the coefficient data corresponding to a frequency that is 3n times (n is a natural number greater than or equal to 1) the electrical angular frequency of the rotating electric machine using the conversion data thinned out by the thinning circuit, and the control circuit is configured to execute an output voltage adjustment process, which is configured to manipulate the output voltage of the inverter based on the coefficient data as an input variable.

[0018] Spatial harmonics in rotating electrical machines tend to be prominent at frequencies 3n times the electrical angular frequency. However, using conversion data sampled at a sampling frequency determined by the requirements of synchronous PWM processing may result in inaccurate calculation of coefficient data corresponding to frequencies 3n times the electrical angular frequency. Therefore, the above configuration thins out the conversion data, allowing the coefficient data to be calculated with the desired resolution. Furthermore, by manipulating the inverter output voltage based on the coefficient data for the frequency components 3n times the electrical angular frequency, it is possible to suppress degradation of the controllability of the rotating electrical machine control variables caused by spatial harmonics.

[0019] A control device of a ninth aspect is a control device according to any one of the third to eighth aspects (excluding those not including the matters of the third aspect) above, wherein the control circuit is configured to execute a diagnostic process, the Fourier transform circuit is configured to calculate the coefficient data corresponding to a frequency that is a rational multiple of the mechanical angular frequency of the rotating electric machine using the conversion data that has been thinned out by the thinning circuit, and the diagnostic process is a process for diagnosing the presence or absence of an abnormality in the controlled object based on the coefficient data as an input variable.

[0020] Because frequencies characteristic of physical quantities resulting from the operation of a rotating electric machine tend to be frequencies that are rational multiples of the rotational speed, the value of the characteristic frequency component tends to vary depending on whether or not there is an abnormality in the rotating electric machine or the equipment driven by the rotating electric machine. However, using conversion data sampled at a sampling frequency determined by the requirements of synchronous PWM processing may result in inaccurate calculation of coefficient data corresponding to the characteristic frequency. Therefore, with the above configuration, by thinning out the conversion data, the coefficient data can be calculated with the desired resolution. This allows for highly accurate diagnosis of the presence or absence of an abnormality. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a block diagram showing a configuration of an air conditioning system according to a first embodiment. [Figure 2] FIG. 2 is a block diagram showing a process executed by a CPU of the control device according to the embodiment. [Figure 3] FIG. 2 is a block diagram showing the configuration of a DFT circuit of the control device according to the embodiment. [Figure 4] 4 is a flowchart showing the procedure of processing executed by a CPU according to the embodiment. [Figure 5] 4 is a flowchart showing the procedure of processing executed by the DFT circuit according to the embodiment. [Figure 6] FIG. 10 is a block diagram showing processing executed by a CPU of a control device according to a second embodiment. [Figure 7]FIG. 10 is a block diagram showing the configuration of a DFT circuit of a control device according to a third embodiment. [Figure 8] 10 is a flowchart showing a procedure of processing executed by a CPU according to a fourth embodiment. [Figure 9] 4 is a flowchart showing the procedure of processing executed by a CPU according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0022] First Embodiment The first embodiment will be described below with reference to the drawings. "Prerequisite configuration" FIG. 1 shows the configuration of an air conditioning system according to this embodiment.

[0023] As an example, the air conditioner 10 receives a supply of power from a system power supply 20. The air conditioner 10 includes a compressor 12. A rotating shaft 12a of the compressor 12 is mechanically coupled to a rotating shaft 14a of a motor 14. As an example, the motor 14 is a three-phase synchronous motor. The motor 14 may be, for example, an interior permanent magnet synchronous motor. The output voltage of an inverter 16 is applied to each terminal of the motor 14. The inverter 16 is a circuit that converts the voltage of a DC voltage source into an AC voltage and applies the AC voltage to the motor 14.

[0024] Inverter 16 has three sets of series-connected upper-arm switching elements S#p and lower-arm switching elements S#n, where #=u, v, w. Freewheel diodes D#p and D#n are connected in anti-parallel to switching elements S#p and S#n, respectively.

[0025] Power from a system power supply 20 is supplied to the input terminal of the inverter 16 via an AC-DC conversion circuit 18. A smoothing capacitor 17 is provided between the AC-DC conversion circuit 18 and the inverter 16.

[0026] The control device 30 includes a CPU 32, a memory 34, a DFT circuit 36, and an AD converter 38. The CPU 32 executes a program stored in the memory 34 to control the control amount of the motor 14, which is the control target of the control device 30. The DFT circuit 36 ​​and the AD converter 38 are hardware processing circuits.

[0027] To control the controlled variable, the CPU 32 refers to the mechanical angle θm of the motor 14 detected by the rotation angle sensor 40. The CPU 32 refers to the detection signal O of the vibration of the compressor 12 detected by the vibration sensor 42. The CPU 32 refers to the current I flowing through the motor 14 detected by the current sensor 44. As an example, the current sensor 44 is configured to include a shunt resistor provided on the negative DC bus of the inverter 16 and a voltage sensor that detects the amount of voltage drop across the shunt resistor. That is, the current I in this embodiment is the current flowing through the negative DC bus. The CPU 32 refers to the input voltage Vin of the inverter 16 detected by the voltage sensor 46.

[0028] "CPU32 processing" Fig. 2 shows part of the processing executed by the CPU 32. The processing shown in Fig. 2 is realized by the CPU 32 repeatedly executing a program stored in the memory 34, for example, at a predetermined interval.

[0029] The target angular velocity setting process M10 is a process for setting a target angular velocity ω*0, which is a target value for the rate of change of the mechanical angle θm. The correction process M12 is a process for substituting a value obtained by correcting the target angular velocity ω*0 using a correction amount Δωc, which will be described later, for the target angular velocity ω*. The angular velocity calculation process M14 is a process for calculating the angular velocity ωm based on the mechanical angle θm, which has been converted into digital data by the AD converter 38, as an input variable. The deviation calculation process M16 is a process for calculating a deviation Δω, which is a value obtained by subtracting the angular velocity ωm from the target angular velocity ω*. The current command value setting process M18 is a process for calculating a d-axis current command value id* and a q-axis current command value iq* based on the deviation Δω as an input variable.

[0030] The electrical angle calculation process M19 is a process of multiplying the mechanical angle θm, which has been converted into digital data by the AD converter 38, by the number of pole pairs p, as an input variable, and dividing the result by 360, and assigning the remainder to the electrical angle θe. The two-phase conversion process M20 is a process of calculating the d-axis current id and the q-axis current iq based on the current I, the switching pattern, and the electrical angle θe, which have been converted into digital data by the AD converter 38, as input variables. The switching pattern is determined by the on / off states of the switching elements S#p and S#n of the inverter 16. The switching pattern determines the voltage vector of the output voltage of the inverter 16. The deviation calculation process M22 is a process of calculating the q-axis current deviation, which is the value obtained by subtracting the q-axis current iq from the q-axis current command value iq*. The deviation calculation process M24 is a process of calculating the d-axis current deviation, which is the value obtained by subtracting the d-axis current id from the d-axis current command value id*.

[0031] The voltage command value setting process M26 sets a command value for the output voltage of the inverter 16 based on the deviation output by the deviation calculation processes M22 and M24, and the q-axis current command value iq* and the d-axis current command value id* as input variables. The voltage command value setting process M26, for example, includes a process of calculating a q-axis voltage command value and a d-axis voltage command value based on the sum of the output value of a proportional element and the output value of a differential element, each of which is an input variable for the pair of deviations. The voltage command value setting process M26 also includes a process of correcting the voltage command value by non-interference control based on the q-axis current command value iq* and the d-axis current command value id* as input variables. The voltage command value setting process M26 may also include a process of correcting the voltage command value for induced voltage compensation based on the rate of change of the electrical angle θe as an input variable.

[0032] The voltage command value setting process M26 is a process for outputting the amplitude Va and the phase δ as variables indicating the output voltage of the inverter 16. The operation signal generation process M28 is a process for calculating operation signals g#p, g#n for the switching elements S#p, S#n based on the amplitude Va and phase δ as input variables. In this embodiment, as an example, the operation signals g#p, g#n are calculated by triangular wave comparison PWM process. In particular, in this embodiment, the operation signals g#p, g#n are calculated by so-called synchronous PWM process, in which the carrier frequency is set to an integer multiple of the electrical angular frequency of the motor 14. In other words, the switching pattern of the inverter 16 is set by synchronous PWM process.

[0033] Figure 2 shows an example in which half a cycle of the U-phase voltage command value vu*, determined by the amplitude Va and phase δ, corresponds to two cycles of a triangular carrier. The PWM signal gu in Figure 2 is determined based on a comparison of the magnitude between the voltage command value vu* and the carrier. Dead time compensation processing is performed on the PWM signal gu to generate the final operation signals gup and gun.

[0034] The vibration suppression process M30 is a process for calculating a correction amount Δωc for suppressing vibration of the compressor 12. This vibration is synchronized with a change in the rotation angle of the rotary shaft 12a of the compressor 12. The input variable of the vibration suppression process M30 is the Fourier amplitude Ift. The Fourier amplitude Ift is calculated by the DFT circuit 36.

[0035] "About DFT Circuit 36" FIG. 3 shows the configuration of the DFT circuit 36. The electrical angle calculation unit 50 is a circuit that calculates the electrical angle θe by multiplying the mechanical angle θm, which has been converted into digital data by the AD converter 38, by the number of pole pairs p, and dividing the resulting value by 360 to obtain the remainder. The q-axis current calculation unit 52 calculates the q-axis current iq based on the current I, which has been converted into digital data by the AD converter 38 as an input variable. To calculate the q-axis current iq, the q-axis current calculation unit 52 refers to the switching pattern of the inverter 16 and the electrical angle θe.

[0036] The thinning circuit 54 is a circuit that selects the q-axis current iq to be used in the FFT 56 by thinning out the time series data of the q-axis current iq calculated by the q-axis current calculation unit 52 . The FFT 56 is a circuit that calculates the Fourier amplitude Ift by fast Fourier transform of the q-axis current selected by the thinning circuit 54. The FFT 56 calculates the Fourier amplitude Ift using, for example, the Cooley-Tukey FFT algorithm.

[0037] The register 58 stores a target frequency ft, which is a frequency at which the Fourier amplitude Ift is to be obtained, and a resolution Δf required for the Fourier amplitude Ift. The sampling frequency setting unit 60 is a circuit that sets the sampling frequency of the AD converter 38 .

[0038] "Setting register 58" Fig. 4 shows the procedure for processing related to setting register 58. The series of processes shown in Fig. 4 is realized by CPU 32 repeatedly executing a program stored in memory 34, for example, at a predetermined interval. Note that, below, the step number of each process is represented by a number preceded by "S."

[0039] In the series of processes shown in Fig. 4, the CPU 32 first acquires the angular velocity ωm (S10). Then, the CPU 32 multiplies the angular velocity ωm by a coefficient Kt and assigns the result to the target frequency ft (S12). The target frequency ft is a frequency for which the Fourier amplitude Ift is to be calculated. The coefficient Kt is a coefficient for converting the angular velocity ωm into the frequency of the load torque caused by the compressor 12. The coefficient Kt is, for example, an integer equal to or greater than 1.

[0040] Next, the CPU 32 sets the resolution Δf (S14). Then, the CPU 32 outputs the target frequency ft and the resolution Δf to the DFT circuit 36 ​​(S16). When the CPU 32 completes the process of S16, it temporarily ends the series of processes shown in FIG.

[0041] "Operation of DFT circuit 36" FIG. 5 shows the operation of the DFT circuit 36 ​​according to the setting of the register 58. The sampling frequency setting unit 60 first multiplies the electrical angular frequency fe by the value of 2 to the power "n" and assigns the result to the PWM frequency fpwm (S20), where "n" is an integer equal to or greater than 1. The sampling frequency setting unit 60 then outputs the PWM frequency fpwm to the AD converter 38 (S22).

[0042] On the other hand, the thinning circuit 54 searches for a value of the thinning interval M that satisfies the following conditions A to D (S24). Condition A: The number of operations N for calculating the Fourier amplitude Ift is 2 to the power "t", where "t" is an integer equal to or greater than 1. This is a condition that takes into account that in FFT algorithms, the number of operations is generally a power of 2.

[0043] Condition B: A value obtained by dividing the sampling frequency fs by the number of calculations N is equal to the resolution Δf. This condition is for satisfying the set resolution Δf. Condition C: The value obtained by dividing the PWM frequency fpwm by the value of the thinning interval M is equal to the sampling frequency fs.

[0044] Condition D: The specified variable k used to determine the target frequency ft is equal to the value obtained by dividing the target frequency ft by the resolution Δf. Here, the specified variable k is a variable that appears in the independent variable of the exponential function in the discrete Fourier transform, "2·π·j·k·m / (2^t)." Note that "2^t" here indicates 2 to the tth power. Also, the variable m is a variable used to add the value of the exponential function from 0 to 2^t-1. Also, the imaginary unit is written as "j."

[0045] The thinning circuit 54 sets the thinning interval M obtained by the process of S24 as the actual thinning interval (S26). The thinning circuit 54 also outputs the value of the designated variable k obtained by the process of S24 to the FFT 56 (S28).

[0046] When the process of S28 is completed, the process of FIG. 5, which is periodically executed, is temporarily terminated. "Actions and Effects of the Present Embodiment" The CPU 32 controls the angular velocity of the motor 14 by synchronous PWM processing. To this end, the CPU 32 samples input variables of the synchronous PWM processing, such as the current I, at a PWM frequency fpwm that is an integer multiple of the electrical angular frequency of the motor 14.

[0047] On the other hand, the DFT circuit 36 ​​shares the AD converter 38 with the CPU 32. Therefore, the output of the AD converter 38 input to the DFT circuit 36 ​​is updated at a cycle that is the reciprocal of the PWM frequency fpwm.

[0048] When the FFT 56 calculates the Fourier amplitude Ift using digital data obtained by sampling where the PWM frequency fpwm is the sampling frequency, it may be difficult to achieve a desired resolution.

[0049] Therefore, the data decimated by the decimation circuit 54 is input to the FFT 56. This allows the sampling frequency of the digital data input to the FFT 56 to be changed with respect to the PWM frequency fpwm, thereby enabling the FFT 56 to calculate the Fourier amplitude Ift with a desired resolution.

[0050] For example, if the angular velocity ωm is 35 Hz, the number of pole pairs p is 3, and the variable n in S20 is 8, the PWM frequency fpwm is set to 105×256=26880 Hz. The CPU 32 then updates the switching pattern based on the sampled values ​​of the current I 256 times per electrical angle period.

[0051] On the other hand, in this case, if the target frequency ft and the resolution Δf are both "35," for example, the thinning interval M by the thinning circuit 54 is set to "1." This allows the FFT 56 to calculate the Fourier amplitude Ift at the desired resolution using all of the current I input to the DFT circuit 36. In other words, the FFT 56 can calculate the Fourier amplitude Ift at the desired resolution without thinning by the thinning circuit 54 using all of the current I input to the DFT circuit 36. However, the number of calculations N in this case is 256.

[0052] However, for example, if the angular velocity ωm and target frequency ft are "30 Hz", the number of pole pairs p is "3", the variable n of S20 is "8", and the resolution Δf is "10", then if no thinning is performed, the number of operations required to meet the resolution Δf requirement will be "9·256". This does not meet the requirement of FFT56 that the number of operations N be a power of 2.

[0053] According to the present embodiment described above, the following actions and effects can be further obtained. (1-1) The sampling frequency of the current I input to the DFT circuit 36 ​​is equal to the sampling frequency of the current I used by the CPU 32 to control the motor 14. Therefore, the sampling frequency of the current input to the DFT circuit 36 ​​is completely determined by the requirements of the synchronous PWM processing. Therefore, the thinning-out circuit 54 is particularly useful.

[0054] (1-2) The DFT circuit 36 ​​includes an FFT 56 that calculates the Fourier amplitude Ift using a fast Fourier transform algorithm. This allows the Fourier amplitude Ift to be calculated efficiently.

[0055] (1-3) The CPU 32 inputs the target frequency ft and the resolution Δf to the register 58, causing the thinning circuit 54 to set the thinning interval M. This allows the CPU 32 to calculate the Fourier amplitude Ift of the target frequency ft intended by the CPU 32 so as to satisfy the resolution Δf.

[0056] (1-4) The torque applied by the compressor 12 to the motor 14 varies depending on the rotation angle of the compressor 12. Therefore, the load torque applied by the compressor 12 to the motor 14 is a rational multiple of the mechanical angle θm of the motor 14. In evaluating the influence of this load torque, the amplitude of the fluctuation component of a frequency that is an integer multiple of the fluctuation period of the load torque applied by the compressor 12 to the motor 14 is effective information. Therefore, the CPU 32 sets the target frequency ft to a rational multiple of the electrical angular frequency. Then, the CPU 32 corrects the target angular velocity ω*0 according to the Fourier amplitude Ift corresponding to the target frequency ft. This makes it possible to suppress torque fluctuations caused by fluctuations in the load torque of the compressor 12.

[0057] <Second embodiment> The second embodiment will be described below with reference to the drawings, focusing on the differences from the first embodiment.

[0058] 6 shows the processing executed by the CPU 32. In FIG. 6, the processing corresponding to the processing shown in FIG. 2 is denoted by the same reference numerals for convenience. As shown in FIG. 6, in the deviation calculation process M16 according to this embodiment, the deviation between the target angular velocity ω* set in the target angular velocity setting process M10 and the angular velocity ωm is input to the current command value setting process M18.

[0059] The phase correction process M30a calculates a correction amount Δδ for correcting the phase δ of the output voltage of the inverter 16 in order to suppress torque ripple caused by spatial harmonics. The correction process M12a is a process in which the phase δ set by the voltage command value setting process M26 is corrected by the correction amount Δδ, and the corrected value is input to the operation signal generation process M28.

[0060] The phase correction process M30a calculates a correction amount Δδ based on the Fourier amplitude Vft as an input variable. The target frequency ft corresponding to the Fourier amplitude Vft is a multiple of three of the angular velocity ωm. Specifically, the target frequency ft is a multiple of three of the electrical angular frequency of the motor 14. This setting takes into account the fact that the spatial harmonics of the motor 14 tend to have prominent frequency components that are 3n times the electrical angular frequency.

[0061] In this embodiment, the input voltage Vin is converted into digital data by the AD converter 38 and input to the DFT circuit 36. The AD converter 38 also sequentially converts analog signals other than the current I into digital data at the sampling period of the current I.

[0062] Here, for example, assume that the angular velocity ωm is 23 Hz, the number of pole pairs p is 4, the target frequency ft is 23 Hz, and the resolution is 1 Hz. In this case, the electrical angular frequency is 92 Hz. The sampling frequency of the AD converter 38 is set to an integer multiple of 92 Hz, for example, 92 × 128 Hz. The thinning circuit 54 then sets the thinning interval M to 92. This allows the number of calculations N to be 128 and the resolution to be 1 Hz.

[0063] <Third embodiment> The third embodiment will be described below with reference to the drawings, focusing on the differences from the first embodiment.

[0064] Fig. 7 shows the configuration of the DFT circuit 36 ​​according to this embodiment. In Fig. 7, circuits corresponding to the circuits shown in Fig. 3 are denoted by the same reference numerals for convenience. 7, this embodiment includes two thinning circuits 54(1) and 54(2) and two FFTs 56(1) and 56(2). In this embodiment, the DFT circuit 36 ​​receives the detection signal O converted into digital data by the AD converter 38. The AD converter 38 also converts the detection signal O into digital data at the sampling period of the current I.

[0065] Fig. 8 shows the procedure for processing related to setting register 58. The series of processes shown in Fig. 8 are realized by CPU 32 repeatedly executing a program stored in memory 34, for example, at a predetermined interval. For convenience, the same step numbers are assigned to processes in Fig. 8 that correspond to those shown in Fig. 4.

[0066] 8, when completing the process of S10, the CPU 32 assigns a value obtained by multiplying the angular velocity ωm by a coefficient Kt(1) to the target frequency ft(1) and assigns a value obtained by multiplying the angular velocity ωm by a coefficient Kt(2) to the target frequency ft(2) (S12a). The coefficients Kt(1) and Kt(2) are coefficients that convert the angular velocity ωm into a frequency that becomes noticeable due to an abnormality in the compressor 12. The coefficients Kt(1) and Kt(2) are rational numbers.

[0067] The CPU 32 sets a resolution Δf(1) for the target frequency ft(1) and a resolution Δf(2) for the target frequency ft(2) (S14a). Then, the CPU 32 outputs the target frequencies ft(1) and ft(2) and the resolutions Δf(1) and Δf(2) to the DFT circuit 36 ​​(S16a).

[0068] When the CPU 32 completes the process of S16a, it temporarily ends the series of processes shown in FIG. 9 shows a procedure for a process related to diagnosing whether or not there is an abnormality in the compressor 12 based on the detection signal O. The process shown in FIG. 9 is realized by the CPU 32 repeatedly executing a program stored in the memory 34, for example, at a predetermined interval.

[0069] 9, the CPU 32 first acquires the Fourier amplitude Oft(1) for the target frequency ft(1) calculated by the FFT 56 (S30). Then, the CPU 32 determines whether the Fourier amplitude Oft(1) is equal to or greater than a threshold Oft1th (S32). This process is for determining whether a first abnormality has occurred in the compressor 12.

[0070] When the CPU 32 determines that the Fourier amplitude Oft(1) is equal to or greater than the threshold value Oft1th (S32: YES), the CPU 32 determines that the compressor 12 has a first abnormality (S34). When the CPU 32 completes the process of S34 or when a negative determination is made in the process of S32, the CPU 32 acquires the Fourier amplitude Oft(2) for the target frequency ft(2) calculated by the FFT 56 (S36). Then, the CPU 32 determines whether the Fourier amplitude Oft(2) is equal to or greater than a threshold value Oft2th (S38). This process is to determine whether a second abnormality has occurred in the compressor 12.

[0071] When the CPU 32 determines that the Fourier amplitude Oft(2) is equal to or greater than the threshold value Oft2th (S38: YES), the CPU 32 determines that the compressor 12 has a second abnormality (S40). It should be noted that the CPU 32 temporarily ends the series of processes shown in FIG. 9 when it completes the process of S40 or when it makes a negative determination in the process of S38.

[0072] For example, consider the case where the angular velocity ωm is 60 Hz, the number of pole pairs p is 3, the target frequencies ft(1) and ft(2) are 60 Hz and 90 Hz, respectively, the resolutions Δf(1) and Δf(2) are 2 Hz and 3 Hz, respectively, and the variable n in S20 is 7. In this case, the PWM frequency fpwm is 180 × 128 = 23,040 Hz. The decimation circuit 54(1) sets the decimation interval M to 90. This allows calculation of the Fourier amplitude Oft(1) when the resolution Δf(1) is 2 Hz and the target frequency ft(1) is 20 Hz. The decimation circuit 54(2) sets the decimation interval M to 60. This allows calculation of the Fourier amplitude Oft(3) when the resolution Δf(2) is 3 Hz and the target frequency ft(2) is 30 Hz.

[0073] According to the present embodiment described above, in addition to the effects (1-1) to (1-3) of the first embodiment, the following actions and effects can be obtained. (3-1) Because frequencies characteristic of physical quantities resulting from the operation of the motor 14 tend to be frequencies that are rational multiples of the electrical angular frequency, the value of the characteristic frequency component tends to differ depending on whether or not there is an abnormality in the motor 14 or the compressor 12 driven by the motor 14. Therefore, the CPU 32 sets the target frequencies ft(1) and ft(2) to these frequencies. This allows the CPU 32 to diagnose whether or not there is an abnormality based on the Fourier amplitudes Oft(1) and Oft(2) as input variables.

[0074] (3-2) A plurality of decimation circuits 54 and FFTs 56 are provided, which allows simultaneous calculation of Fourier amplitudes Oft(1) and Oft(2) at different target frequencies ft(1) and ft(2).

[0075] <Correspondence> The correspondence between the matters in the above embodiments and the matters described in the "Means for Solving the Problems" section is as follows. Below, the correspondence is shown for each number of the viewpoints described in the "Means for Solving the Problems" section. [1, 2, 5] The control circuit corresponds to the CPU 32. The AD converter corresponds to the AD converter 38. The decimation circuit corresponds to the decimation circuits 54, 54(1), and 54(2). The Fourier transform circuit corresponds to the FFTs 56, 56(1), and 56(2). The first digital data, the second digital data, and the conversion data correspond to the current I, the current I, and the q-axis current iq, respectively, in the first embodiment. The first digital data, the second digital data, and the conversion data correspond to the current I, the input voltage Vin, and the input voltage Vin, respectively, in the second embodiment. The first digital data, the second digital data, and the conversion data correspond to the current I, the detection signal O, and the detection signal O, respectively, in the third embodiment. [3] The rotating electric machine corresponds to the motor 14. [4] The first and second thinning circuits correspond to the thinning circuits 54(1) and 54(2). The first and second Fourier transform circuits correspond to the FFTs 56(1) and 56(2). [6] The frequency identification data corresponds to the data indicating the target frequency ft. [7] The output voltage adjustment process corresponds to the process shown in Figure 2. [8] The output voltage adjustment process corresponds to the process shown in Figure 6. [9] The diagnosis process corresponds to the process shown in Figure 9.

[0076] <Other embodiments> This embodiment can be modified as follows: This embodiment and the following modifications can be combined and implemented within the scope of technical compatibility.

[0077] "About the sampling frequency setting unit 60" In the above embodiment, there is no particular mention of taking into account factors such as the resolution Δf of the coefficient data when the sampling frequency setting unit 60 sets the PWM frequency fpwm, but the resolution Δf may also be taken into account. In more detail, for example, the DFT circuit 36 ​​may execute a process for simultaneously determining the thinning interval M, the PWM frequency fpwm, and the number of calculations N. This more reliably prevents a situation in which coefficient data satisfying the resolution Δf cannot be set despite the execution of the thinning process.

[0078] The sampling frequency setting unit 60 does not necessarily have to be packaged together with the FFT 56 and the like. It is not essential that the control device 30 includes the sampling frequency setting unit 60 as a hardware processing circuit. For example, the processes of S20 and S22 may be executed by the CPU 32.

[0079] "About thinning circuits" The number of thinning circuits provided in the control device 30 is not limited to one or two. For example, it may be three or more.

[0080] It is not essential that the decimation circuit be packaged together with the Fourier transform circuit. It is not essential that the thinning circuit executes the processes of S24 to S28. For example, if there is a situation where the target frequency Ft is predetermined to one, the thinning circuit may be a circuit that simply executes thinning processing according to an invariable thinning interval M.

[0081] "About Fourier transform circuits" The number of decimation circuits does not necessarily have to be the same as the number of Fourier transform circuits. For example, one decimation circuit may be provided with multiple Fourier transform circuits. Here, if the sampling timing of the first data in the time-series data for conversion data used by different Fourier transform circuits to calculate coefficient data is different, the coefficient data update cycle can be shortened.

[0082] The fast Fourier transform algorithm does not necessarily have to be a Cooley-Tukey FFT algorithm. The Fourier transform circuit does not necessarily have to be a circuit that calculates coefficient data based on the fast Fourier transform algorithm.

[0083] "About DFT circuits" It is not essential that the DFT circuit 36 ​​include the q-axis current calculation unit 52. In this case, it is not essential that the q-axis current iq input to the thinning circuit 54 be a value calculated by a hardware processing circuit. For example, the q-axis current iq input to the thinning circuit 54 may be a value calculated by the CPU 32. "About conversion data" The conversion data related to the current of motor 14 is not limited to the q-axis current iq. The conversion data related to the current of motor 14 may be, for example, the d-axis current id. The conversion data related to the current of motor 14 may be, for example, the current I. Furthermore, the conversion data related to the current of motor 14 may be, for example, the output line current of inverter 16. Furthermore, the conversion data related to the current of motor 14 may be, for example, an α-phase current or a β-phase current obtained by performing a two-phase conversion on the output line current of inverter 16. The conversion data related to the current of motor 14 may be, for example, an M-axis current or a T-axis current obtained by a coordinate conversion based on the angle of the primary magnetic flux of motor 14. Note that the coordinate conversion used to generate the conversion data related to the current of motor 14 is not limited to the examples given above. The conversion data related to the current of motor 14 does not necessarily have to be data on a current that fluctuates from moment to moment. The conversion data related to the current of motor 14 may be, for example, a quantity proportional to the amplitude of the output line current, the α-phase current, or the β-phase current, or the square of that quantity. Furthermore, for example, the conversion data related to the current of motor 14 may be a quantity related to the difference between the maximum and minimum values ​​of the q-axis current or the d-axis current. The conversion data related to the voltage of the motor 14 is not limited to the input voltage Vin. The conversion data related to the voltage of the motor 14 may be, for example, the output line voltage of the inverter 16. Furthermore, the conversion data related to the voltage of the motor 14 may be, for example, the d-axis voltage or the q-axis voltage. Note that the coordinate transformation used to generate the conversion data related to the voltage of the motor 14 is not limited to coordinate transformation to the dq axes. The conversion data for the voltage of motor 14 does not necessarily have to be data on a voltage that fluctuates from moment to moment. The conversion data for the voltage of motor 14 may be a quantity proportional to the amplitude of the output line voltage or the square of that quantity. For example, the conversion data for the voltage of motor 14 may also be a quantity related to the difference between the maximum and minimum values ​​of the d-axis voltage or the q-axis voltage. The conversion data may be, for example, the instantaneous power of the motor 14. The power-related conversion data may be, for example, the instantaneous imaginary power, apparent power, active power, or reactive power. The conversion data may be, for example, armature flux linkage. The conversion data relating to magnetic flux may be, for example, d-axis magnetic flux or q-axis magnetic flux. The conversion data may be, for example, a physical quantity such as a magnetic pole position or the torque of the motor 14, which is estimated using a physical model based on the detected values ​​of a sensor. The analog signal for generating the digital data as the conversion data may be, for example, a magnetic pole position signal obtained by an encoder or the like. Alternatively, the analog signal for generating the digital data as the conversion data may be, for example, a sound signal obtained by a sound sensor that detects sound around the motor 14. Alternatively, the analog signal for generating the digital data as the conversion data may be, for example, a temperature signal obtained by a temperature sensor that detects the temperature around the motor 14. "About the coefficient data" The coefficient data does not necessarily have to be data related only to the amplitude of the target frequency component. The coefficient data may be data related to both the amplitude and phase of the target frequency component, for example.

[0084] "Countermeasures for load torque pulsation" The manipulated variable for the process of suppressing the load torque does not necessarily have to be the correction variable Δωc for the target angular velocity ω*. The manipulated variable for the process of suppressing the load torque may be, for example, either the amplitude Va or the phase δ of the output voltage of the inverter 16.

[0085] The Fourier coefficients used as inputs to the load torque pulsation countermeasure processing are not limited to those related to a single frequency. The Fourier coefficients used as inputs to the load torque pulsation countermeasure processing may be those related to a plurality of different frequencies.

[0086] The input variable of the FFT 56 for calculating the Fourier amplitude Ift, which is input to the processing for countering load torque pulsation, does not necessarily have to be the q-axis current iq. The input variable of the FFT 56 may be, for example, the U-phase current. Also, for example, the input variable of the FFT 56 may be the current I.

[0087] "Suppression of torque ripple caused by spatial harmonics" The manipulated variable for the process of suppressing torque ripple caused by spatial harmonics does not necessarily have to be the phase δ. The manipulated variable for the process of suppressing torque ripple caused by spatial harmonics may be, for example, the amplitude Va of the output voltage of the inverter 16.

[0088] The input variables of the torque ripple suppression process due to spatial harmonics do not necessarily have to be Fourier coefficients related to a single harmonic. For example, the input variables of the torque ripple suppression process due to spatial harmonics may be Fourier coefficients related to multiple different harmonics.

[0089] "About output voltage adjustment processing" The dq-axis current feedback process is not limited to a process using PD control. For example, the dq-axis current feedback process may be a process using PID control. Furthermore, the dq-axis current feedback process is not limited to classical control, and may be, for example, model predictive control.

[0090] The output voltage adjustment process does not necessarily have to include d-axis and q-axis current feedback processing. For example, the output voltage adjustment process may be processing related to direct torque control.

[0091] "Regarding the control amount of motor 14" The control amount of the motor 14 does not necessarily have to be the angular velocity ωm. The control amount of the motor 14 may be, for example, the torque of the motor 14.

[0092] "About rotating electrical machines" The rotating electric machine is not limited to the motor 14 that drives the compressor 12. For example, it may be a motor mounted on a circulator.

[0093] "About motors" The motor is not limited to an interior permanent magnet synchronous motor, but may be, for example, an induction motor. Also, the motor may be, for example, a brushed DC motor.

[0094] "Software Processing Circuits" The software processing circuit does not necessarily have to be a CPU. For example, the software processing circuit may include a CPU and a GPU.

[0095] "About the control device" The object to be controlled by the control device is not limited to the motor 14 that drives the compressor 12.

[0096] Although the embodiments have been described above, it will be understood that various changes in form and details can be made without departing from the spirit and scope of the claims. [Explanation of symbols]

[0097] 10...Air conditioner 12...Compressor 14...Motor 30...Control device

Claims

1. A control device for controlling a control amount of a control object, The digital signal processing device comprises a control circuit (32), an AD converter (38) for converting an analog signal into digital data, a thinning circuit (54), and a Fourier transform circuit (56), the control circuit (32) is configured to execute a process of controlling the controlled variable based on first digital data, which is the digital data obtained by converting a predetermined analog signal by the AD converter (38); the Fourier transform circuit (56) is configured to output coefficient data, which is data indicating Fourier coefficients, to the control circuit (32) based on the time series data of the transform data; the conversion data is second digital data, which is the digital data converted by the AD converter (38), or data calculated from the second digital data; the second digital data is data synchronized with the first digital data, The thinning circuit (54) is a control device that selects the conversion data to be used in calculating the coefficient data by thinning out the time series data.

2. 2. The control device according to claim 1, wherein the sampling frequency of the data for conversion is equal to the sampling frequency of the first digital data input to the control circuit (32).

3. the controlled object is a rotating electric machine (14), The rotating electric machine (14) is configured so that an output voltage of an inverter (16) is applied to a terminal thereof, the AD converter (38) is configured to convert the predetermined analog signal into the first digital data at a frequency that is an integer multiple of an electrical angular frequency of the rotating electric machine (14); The control circuit (32) is configured to perform synchronous PWM processing; 3. The control device according to claim 2, wherein the synchronous PWM processing is processing for setting a switching pattern of the inverter (16) based on the first digital data as an input variable each time the predetermined analog signal is converted into the first digital data at the integral multiple frequency.

4. the thinning circuit (54) includes a first thinning circuit (54(1)) and a second thinning circuit (54(2)); the Fourier transform circuit (56) includes a first Fourier transform circuit (56(1)) and a second Fourier transform circuit (56(2)); The first thinning circuit (54(1)) and the second thinning circuit (54(2)) have different intervals for thinning out the conversion data, the first Fourier transform circuit (56(1)) is configured to calculate the coefficient data using the transform data decimated by the first decimation circuit (54(1)); 2. The control device according to claim 1, wherein the second Fourier transform circuit (56(2)) is configured to calculate the coefficient data using the transform data decimated by the second decimation circuit (54(2)).

5. 2. The control system of claim 1, wherein the Fourier transform circuitry (56) is configured to generate the coefficient data by a fast Fourier transform.

6. the control circuit (32) is configured to input frequency identification data, which is data for identifying a frequency for which a Fourier coefficient is to be calculated, to the Fourier transform circuit (56); 2. The control device according to claim 1, wherein the thinning circuit (54) is configured to select the conversion data to be used in calculating the coefficient data by thinning the conversion data in accordance with the frequency identification data.

7. The rotating electric machine (14) is a motor that drives a compressor, The motor is configured so that the output voltage of an inverter (16) is applied to the terminals of the motor; the Fourier transform circuit (56) is configured to calculate the coefficient data corresponding to a frequency that is a rational multiple of the mechanical angular frequency of the motor, using the transformation data that has been thinned out by the thinning circuit (54); The control circuit (32) is configured to perform an output voltage regulation process; 4. The control device according to claim 3, wherein the output voltage regulation process is configured to manipulate the output voltage of the inverter (16) based on the coefficient data as an input variable.

8. The rotating electric machine (14) is configured so that an output voltage of an inverter (16) is applied to a terminal thereof, the Fourier transform circuit (56) is configured to calculate the coefficient data corresponding to a frequency that is 3n times (n is a natural number equal to or greater than 1) the electrical angular frequency of the rotating electric machine (14) using the conversion data that has been thinned out by the thinning circuit (54); The control circuit (32) is configured to perform an output voltage regulation process; 4. The control device according to claim 3, wherein the output voltage regulation process is configured to manipulate the output voltage of the inverter (16) based on the coefficient data as an input variable.

9. The control circuit (32) is configured to perform a diagnostic process; the Fourier transform circuit (56) is configured to calculate the coefficient data corresponding to a frequency that is a rational multiple of a mechanical angular frequency of the rotating electric machine (14) using the transformation data decimated by the decimation circuit (54); 4. The control device according to claim 3, wherein the diagnostic process is a process for diagnosing the presence or absence of an abnormality in the controlled object based on the coefficient data as an input variable.

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