Control device

Abstract

Each time digital data of a detected current I is generated by an AD converter, a q-axis current (iq) corresponding to the current I is multiplied by a sine function value in a multiplication unit (60) in an arithmetic circuit (36), and by a cosine function value in a multiplication unit (62) in the arithmetic circuit (36), the arithmetic circuit (36) being provided in a control device. The values outputted by the multiplication units (60, 62) are integrated in integration processing units (68, 70). The sampling frequency of an AD converter (50) and the number of integrations performed in the integration processing units (68, 70) are changed by the setting of a register (74).

Description

Control device

[0006]

[0001] This disclosure relates to a control device.

[0002] Patent Document 1 describes a control device that executes a process of correcting a target value of the rotational speed of a motor according to a frequency fluctuation component obtained by Fourier-transforming the rotational speed of the motor. This process aims to suppress fluctuations in the output torque of the motor.

[0003] Japanese Patent Application Laid-Open No. 2016-127649

[0004] The frequency of the frequency fluctuation component desired in motor control changes depending on the rotational speed of the motor. Therefore, when the sampling period of the rotational speed is fixed, the calculation accuracy of the frequency fluctuation component may decrease depending on the rotational speed.

[0005] The control device from the first aspect for solving the problem is a control device that controls a control amount of a control target, and includes a software processing circuit and a hardware processing circuit. The hardware processing circuit includes an AD converter that converts an analog signal into digital data, and a Fourier transform circuit that converts conversion data into coefficient data. When frequency specification data is input from the software processing circuit to the hardware processing circuit, the hardware processing circuit is configured to output to the software processing circuit coefficient data calculated using at least one of a sampling frequency and a number of operations according to the frequency specification data that is changed under a predetermined condition. The conversion data is the digital data or data calculated from the digital data. The frequency specification data is data for determining the frequency for which Fourier coefficients are to be obtained. The coefficient data is data indicating the Fourier coefficients of the frequency specified by the frequency specification data. The software processing circuit is configured to execute a predetermined process related to the control target based on the coefficient data as an input variable.

[0006] According to the above configuration, the Fourier transform circuit can set its frequency resolution to an appropriate resolution for the frequency for which the Fourier coefficients are to be determined by changing at least one of the two factors: the sampling frequency and the number of operations, depending on the frequency for which the Fourier coefficients are to be determined.

[0007] The control device in the second aspect is the control device in the first aspect, wherein the Fourier transform circuit includes a first Fourier transform circuit and a second Fourier transform circuit, the software processing circuit is configured to input the first frequency-specific data as frequency-specific data to the first Fourier transform circuit and to input the second frequency-specific data as frequency-specific data to the second Fourier transform circuit, the first Fourier transform circuit is configured to output the coefficient data calculated using at least one of the first frequency-specific data to the software processing circuit when the first frequency-specific data is input, and the second Fourier transform circuit is configured to output the coefficient data calculated using at least one of the second frequency-specific data to the software processing circuit when the second frequency-specific data is input.

[0008] In the above configuration, by providing a first Fourier transform circuit and a second Fourier transform circuit, it is possible to handle cases where there are two frequencies for which the Fourier coefficients are to be determined. In the control device according to the third aspect, in the control device according to the first or second aspect, the Fourier transform circuit is configured to perform a process that generates a first integrated value obtained by multiplying the value indicated by the corresponding conversion data by the value of a sine function of a predetermined phase and integrating the results, and a second integrated value obtained by multiplying the value of a cosine function of a predetermined phase and integrating the results, each time the analog signal is converted to digital data by the AD converter.

[0009] In the above configuration, each time an analog signal is converted to digital data, the value indicated by the corresponding conversion data is multiplied by the values ​​of the sine function and the cosine function, respectively, and then the result is accumulated. This eliminates the need to temporarily store a large amount of digital data. Therefore, the storage capacity can be reduced.

[0010] The control device according to the fourth aspect is the control device according to any one of the first to third aspects, wherein the AD converter is a first AD converter, and the control device includes a second AD converter separate from the first AD converter, and is configured such that the digital data output by the second AD converter is input to the software processing circuit.

[0011] In the above configuration, the second AD converter used by the software processing circuit and the first AD converter that generates the input data for the Fourier transform circuit are separate. This makes it possible to suppress interference between the requirements of the software processing circuit and the requirements of the Fourier transform circuit for the first AD converter.

[0012] The control device according to the fifth aspect is the control device according to any one of the first to fourth aspects described above, wherein the software processing circuit is configured to input resolution specification data to the hardware processing circuit, and the resolution specification data is data that specifies at least one of the frequency specification data.

[0013] In the above configuration, the software processing circuit specifies at least one of the two factors necessary for accurately determining the Fourier coefficients—the sampling frequency and the number of calculations—so the hardware processing circuit does not need to have the function to perform calculations to determine these factors. Therefore, the hardware processing circuit can be designed more simply.

[0014] The control device in the sixth aspect is the control device described in any one of the first to fifth aspects, wherein the controlled object is a rotating electric machine. The characteristic frequencies of physical quantities resulting from the operation of a rotating electric machine tend to be frequencies that are rational multiples of the rotational speed. Furthermore, if the characteristic frequency is the frequency for which we want to find the Fourier coefficients, the frequency for which we want to find the Fourier coefficients tends to fluctuate depending on the rotational speed of the rotating electric machine. For this reason, the usefulness of a process that changes at least one of the two, the sampling frequency and the number of calculations, is particularly great.

[0015] The control device described in Perspective 7 is a control device described in the sixth perspective, wherein the rotating electric machine is a motor that drives a compressor, the output voltage of an inverter is applied to the terminals of the motor, the software processing circuit is configured to perform frequency specification processing and output voltage adjustment processing, the frequency specification processing is a process of inputting data relating to frequencies that are rational multiples of the mechanical angular frequency of the motor as frequency specification data to the hardware processing circuit, and the output voltage adjustment processing is a process of manipulating 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 fluctuates according to the compressor's rotation angle. Therefore, the load torque applied by the compressor to the motor is a rational number 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. In the above configuration, by specifying the frequency of this fluctuation component using frequency-specific data, coefficient data related to the Fourier coefficient of this fluctuation component can be obtained. Then, by manipulating the inverter's output voltage based on this coefficient data, torque fluctuations can be suppressed.

[0017] The control device described in the eighth aspect is the control device described in the sixth or seventh aspect, wherein the output voltage of the inverter is applied to the terminals of the rotating electric machine, the software processing circuit is configured to perform frequency specification processing and output voltage adjustment processing, the frequency specification processing is a process of inputting data relating to a frequency that is 3n times the electrical angular frequency of the rotating electric machine (where n is a natural number of 1 or more) as frequency specification data to the hardware processing circuit, and the output voltage adjustment processing is configured to operate the output voltage of the inverter based on the coefficient data as an input variable.

[0018] Spatial harmonics in rotating electric machines tend to show a prominent frequency component at 3n times the electrical angular frequency. Therefore, in the above configuration, frequency identification data indicating that this component is the frequency for which the Fourier coefficients are to be calculated is input to the hardware processing circuit. By then manipulating the inverter output voltage based on the coefficient data of the frequency component at 3n times the electrical angular frequency, the decrease in controllability of the controllable variable of the rotating electric machine caused by spatial harmonics can be suppressed.

[0019] The control device described in viewpoint 9 is a control device described in any one of viewpoints 6 to 8, wherein the software processing circuit is configured to perform frequency specification processing and diagnostic processing, the frequency specification processing is a process of inputting data relating to frequencies that are rational multiples of the mechanical angular frequency of the rotating electric machine as frequency specification data to the hardware processing circuit, and the diagnostic processing is a process of diagnosing whether or not there is an abnormality in the controlled object based on the coefficient data.

[0020] The characteristic frequencies of physical quantities resulting from the operation of a rotating electric machine tend to be rational multiples of the rotational speed. Therefore, these characteristic frequency components tend to differ depending on whether or not there is a malfunction in the rotating electric machine or the equipment driven by it. In the above configuration, frequency identification data indicating that this component is the frequency for which the Fourier coefficients are to be calculated is input to the hardware circuit. Then, by diagnosing the presence or absence of a malfunction based on the Fourier coefficients of this frequency, the presence or absence of a malfunction can be appropriately diagnosed.

[0021] The control device described in the tenth aspect is the control device described in the ninth aspect, wherein the Fourier transform circuit includes a first Fourier transform circuit and a second Fourier transform circuit, the software processing circuit is configured to input the same frequency-specific data to both the first Fourier transform circuit and the second Fourier transform circuit, and the first Fourier transform circuit and the second Fourier transform circuit are configured to output coefficient data corresponding to time-series data of different digital data, using the digital data output by the AD converter at different sampling timings as the initial input data.

[0022] The time required to calculate coefficient data is greater than the time from input of the first data to input of the last data in a time series data consisting of multiple digital data. Therefore, in the above configuration, the time interval at which new coefficient data is calculated can be shortened by having the first and second Fourier transform circuits output coefficient data using different time series data. As a result, the update interval of the diagnostic results can be shortened.

[0023] This is a block diagram showing the configuration of an air conditioning system according to the first embodiment. This is a block diagram showing the processing performed by the CPU of the control device according to the same embodiment. This is a block diagram showing the configuration of the arithmetic circuit of the control device according to the same embodiment. This is a flowchart showing the procedure of processing performed by the CPU according to the same embodiment. This is a block diagram showing the configuration of the arithmetic circuit according to the second embodiment. This is a block diagram showing the configuration of an air conditioning system according to the third embodiment. This is a block diagram showing the processing performed by the CPU according to the same embodiment. This is a flowchart showing the procedure of processing performed by the CPU according to the fourth embodiment.

[0024] <First Embodiment> The first embodiment will be described below with reference to the drawings. "Prerequisite Configuration" Figure 1 shows the configuration of the air conditioning system according to this embodiment.

[0025] The air conditioning system 10 receives power from, for example, a grid power supply 20. The air conditioning system 10 includes a compressor 12. The rotating shaft 12a of the compressor 12 is mechanically connected to the rotating shaft 14a of a motor 14. The motor 14 is, for example, a three-phase synchronous motor. The motor 14 may also be, for example, an embedded magnet synchronous motor. The output voltage of the 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 it to the motor 14.

[0026] The inverter 16 has three series connections of switching elements S#p on the upper arm and S#n on the lower arm, where "# = u, v, w". Freewheeling diodes D#p and D#n are connected in antiparallel to each of these switching elements S#p and S#n.

[0027] Power from the grid power supply 20 is supplied to the input terminals of the inverter 16 via the AC / DC conversion circuit 18. A smoothing capacitor 17 is provided between the AC / DC conversion circuit 18 and the inverter 16.

[0028] The control device 30 comprises a CPU 32, memory 34, arithmetic circuit 36, and AD converter 38. The CPU 32 controls the control amount of the motor 14, which is the object controlled by the control device 30, by executing a program stored in the memory 34. The arithmetic circuit 36 ​​and AD converter 38 are hardware processing circuits.

[0029] The CPU 32 refers to the mechanical angle θm of the motor 14 detected by the rotation angle sensor 40 in order to control the control variable. The CPU 32 also refers to the vibration detection signal O of the compressor 12 detected by the vibration sensor 42. The CPU 32 also refers to the current I flowing through the motor 14 detected by the current sensor 44. The current sensor 44 is configured, for example, with a shunt resistor provided on the DC bus on the negative side of the inverter 16 and a voltage sensor that detects the voltage drop across the shunt resistor. In other words, the current I in this embodiment is the current flowing through the DC bus on the negative side. The CPU 32 also refers to the input voltage Vin of the inverter 16 detected by the voltage sensor 46.

[0030] "CPU Processing" Figure 2 shows a part of the processing performed by the CPU 32. The processing shown in Figure 2 is achieved by the CPU 32 repeatedly executing a program stored in memory 34, for example, at a predetermined cycle.

[0031] The target angular velocity setting process M10 is the process of setting the target angular velocity ω*0, which is the target value of the rate of change of the machine angle θm. The correction process M12 is the process of substituting the value obtained by correcting the target angular velocity ω*0 by the correction amount Δωc, which will be described later, into the target angular velocity ω*. The angular velocity calculation process M14 is the process of calculating the angular velocity ωm based on the machine angle θm, which has been converted into digital data by the AD converter 38, as an input variable. The deviation calculation process M16 is the process of calculating the deviation Δω, which is the value obtained by subtracting the angular velocity ωm from the target angular velocity ω*. The current command value setting process M18 is the process of calculating the current command value id* for the d axis and the current command value iq* for the q axis based on the deviation Δω as an input variable.

[0032] The electrical angle calculation process M19 is a process that assigns the remainder obtained by dividing the value obtained 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, by 360, to the electrical angle θe. The two-phase conversion process M20 is a process that calculates the d-axis current id and the q-axis current iq based on the input variables: the current I, which has been converted into digital data by the AD converter 38, the switching pattern, and the electrical angle θe. The switching pattern is determined by the on and 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 that calculates 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 that calculates 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*.

[0033] The voltage command value setting process M26 is a process that sets the output voltage command value of the inverter 16 based on the deviation output of the deviation calculation processes M22 and M24, the q-axis current command value iq*, and the d-axis current command value id*, which are input variables. As an example, the voltage command value setting process M26 includes a process to calculate the q-axis voltage command value and the d-axis voltage command value based on the sum of the output values ​​of the proportional element and the differential element, each of which is an input variable of the pair of deviations. Furthermore, the voltage command value setting process M26 includes a process to correct the above voltage command value by non-interference control based on the q-axis current command value iq* and the d-axis current command value id*, which are input variables. The voltage command value setting process M26 may also include a process to correct the above voltage command value for induced voltage compensation based on the rate of change of the electrical angle θe, which is an input variable.

[0034] The voltage command value setting process M26 outputs amplitude Va and phase δ as variables indicating the output voltage of the inverter 16. The operation signal generation process M28 calculates the operation signals g#p and g#n for the switching elements S#p and S#n based on the amplitude Va and phase δ as input variables.

[0035] The vibration suppression process M30 is a process that calculates a correction amount Δωc to suppress the vibration of the compressor 12. This vibration is synchronized with the change in the rotation angle of the rotation shaft 12a of the compressor 12. The input variable for the vibration suppression process M30 is the Fourier amplitude Ift. The Fourier amplitude Ift is calculated by the calculation circuit 36.

[0036] "Configuration of the Arithmetic Circuit 36" Figure 3 shows the configuration of the arithmetic circuit 36. The AD converter 50 is a circuit that converts an input analog signal into digital data. The AD converter 50 is a dedicated hardware circuit used for processing within the arithmetic circuit 36, separate from the AD converter 38 used by the CPU 32.

[0037] The electrical angle calculation unit 52 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 50, by the number of pole pairs p and then dividing the result by 360. The q-axis current calculation unit 54 is a process that calculates the q-axis current iq based on the current I, which has been converted into digital data by the AD converter 50 as an input variable. The q-axis current calculation unit 54 refers to the switching pattern of the inverter 16 and the electrical angle θe in order to calculate the q-axis current iq.

[0038] The q-axis current iq is input to the DFT circuit 55. In the DFT circuit 55, the sine function value calculation unit 64 is a circuit that calculates the value of the dependent variable of a sine function in which "2・π・k・m / N" is the independent variable. Here, the number of operations N, the specified variable k, and the counter m are used. These variables will be described in detail later. The cosine function value calculation unit 66 is a circuit that calculates the value of the dependent variable of a cosine function in which "2・π・k・m / N" is the independent variable.

[0039] The multiplication unit 60 is a circuit that calculates a value obtained by multiplying the q-axis current iq by the value of the sine function. The multiplication unit 62 is a circuit that calculates a value obtained by multiplying the q-axis current iq by the value of the cosine function. The integration unit 68 is a circuit that sequentially integrates the value calculated by the multiplication unit 60 each time a new value is calculated. The integration unit 70 is a circuit that sequentially integrates the value calculated by the multiplication unit 62 each time a new value is calculated.

[0040] The Fourier amplitude calculation unit 72 is a circuit that calculates the Fourier amplitude Ift, which is the square root of the sum of the squares of the output values ​​of the integration processing units 68 and 70. The register 74 stores data related to the sampling frequency fs of the AD converter 50, the number of operations N which is the number of integration operations performed by the integration processing units 68 and 70, and the target frequency ft. The target frequency ft is the frequency for which the Fourier amplitude Ift is to be calculated.

[0041] The AD converter 50 converts an input analog signal into digital data according to the sampling frequency fs stored in the register 74. In the present embodiment, as an example, the AD converter 50 periodically converts the current I and the mechanical angle θm into digital data at a period that is the reciprocal of the sampling frequency fs. The change of the sampling frequency by the AD converter 50 is realized, for example, by mounting an operating clock that is sufficiently higher than the assumed sampling frequency fs on the AD converter 50. That is, the sampling frequency fs is realized by thinning out the operating clock.

[0042] The integration processing units 68 and 70 output the integrated value according to the number of operations N stored in the register 74 to the Fourier amplitude calculation unit 72, and then repeat the process of initializing the integrated value. Further, the sine function value calculation unit 64 and the cosine function value calculation unit 66 initialize the counter m each time the integrated value is initialized.

[0043] Note that the arithmetic circuit 36 according to the present embodiment is integrated into one chip as an example. The setting of the register 74 is executed by the CPU 32. "Setting of the register 74" Fig. 4 shows the procedure of the process related to the setting of the register 74. The process shown in Fig. 4 is realized by the CPU 32 repeatedly executing the program stored in the memory 34, for example, at a predetermined period. In the following, the step numbers of each process are represented by numbers with "S" added at the beginning.

[0044] In the series of processes shown in Fig. 4, the CPU 32 first acquires the angular velocity ωm (S10). Next, the CPU 32 substitutes the value obtained by multiplying the angular velocity ωm by the coefficient Kt into the target frequency ft (S12). The target frequency ft is the frequency for which the Fourier amplitude Ift is to be obtained. 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 of 1 or more.

[0045] Next, the CPU 32 substitutes the value obtained by dividing the target frequency ft by the resolution required value M into the resolution Δf (S14). Then, the CPU 32 searches for the number of operations N and the sampling frequency fs that satisfy the following conditions A and B (S16).

[0046] Condition A: A condition that the value obtained by dividing the sampling frequency fs by the number of operations N is equal to the resolution Δf. Condition B: A condition that the sampling frequency fs is not less than the lower limit value fsL and not more than the upper limit value fsH.

[0047] The CPU 32 outputs the target frequency ft, the number of operations N obtained by the S16 process, and the sampling frequency fs to the arithmetic circuit 36 (S18). When the CPU 32 completes the process of S18, the series of processes shown in FIG. 4 is temporarily terminated.

[0048] "Operations and Effects of the Present Embodiment" The CPU 32 sets the target frequency ft to the frequency corresponding to the fluctuation frequency of the load torque of the compressor 12 or its harmonic based on the angular velocity ωm as an input variable. Then, the CPU 32 sets the sampling frequency fs and the number of operations N so as to satisfy a desired resolution, and transmits them to the arithmetic circuit 36.

[0049] Thereby, the target frequency ft, the number of operations N, and the sampling frequency fs are stored in the register 74 of the arithmetic circuit 36. Hereinafter, the operation of the arithmetic circuit 36 will be described by taking as an example the case where the target frequency ft is 30 Hz, the sampling frequency fs is 6000 Hz, and the number of operations N is 200 times.

[0050] The AD converter 50 of the arithmetic circuit 36 ​​samples the current I and the mechanical angle θm at a period of "1 / 6000s", which is the reciprocal of the sampling frequency fs. Meanwhile, the sine function value calculation unit 64 and the cosine function value calculation unit 66 set the specified variable k to "1" because the target frequency ft is 30 Hz. The sine function value calculation unit 64 and the cosine function value calculation unit 66 then increment the counter m each time the digital data of the current I is updated at a period of "1 / 6000s". The integration processing units 68 and 70 integrate the output values ​​of the multiplication units 60 and 62, which are updated at a period of "1 / 6000s". After the integration processing is performed 200 times, the integration processing units 68 and 70 output the integrated value to the Fourier amplitude calculation unit 72. The Fourier amplitude calculation unit 72 calculates the Fourier amplitude Ift based on the output values ​​of the integration processing units 68 and 70. When the Fourier amplitude is calculated by the Fourier amplitude calculation unit 72, the counter m and the integrated values ​​of the integration processing units 68 and 70 are initialized.

[0051] Thus, in this embodiment, the number of calculations N and the sampling frequency fs are changed to appropriate values ​​according to the target frequency ft, which fluctuates in accordance with the change in angular velocity ωm. Therefore, a Fourier amplitude Ift with the desired resolution can be calculated. Moreover, by implementing the calculation circuit 36 ​​with a dedicated hardware processing circuit separate from the CPU 32, the computational load on the CPU 32 can be reduced even when the control device 30 performs the Fourier transform.

[0052] As described above, the following effects and advantages can be obtained with respect to this embodiment. (1-1) The arithmetic circuit 36 ​​is a circuit that, each time a new q-axis current iq is calculated, performs the following operations: multiplying the q-axis current iq by "sin(2・π・k・m・N)" and integrating, and multiplying the q-axis current iq by "cos(2・π・k・m・N)" and integrating. Therefore, compared to, for example, the case where the Fourier amplitude Ift is calculated using the FFT algorithm, the amount of storage capacity required to store the data can be reduced.

[0053] (1-2) The arithmetic circuit 36 ​​is equipped with an AD converter 50 separate from the AD converter 38 that generates the digital data used by the CPU 32. This allows the sampling frequency of the AD converter 50 to be set independently of the sampling frequency of the AD converter 38. Therefore, interference between the CPU 32's request for digital data conversion and the arithmetic circuit 36's request for sampling frequency can be suppressed.

[0054] (1-3) The CPU 32 outputs the sampling frequency fs and the number of operations N to the arithmetic circuit 36. As a result, the arithmetic circuit 36 ​​does not need to set the sampling frequency fs and the number of operations N from the target frequency ft, thus simplifying the configuration of the arithmetic circuit 36.

[0055] (1-4) The torque applied by the compressor 12 to the motor 14 fluctuates according to the rotation angle of the compressor 12. Therefore, the load torque applied by the compressor 12 to the motor 14 is a rational number multiple of the mechanical angle θm of the motor 14. In evaluating 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 12 to the motor 14 is useful information. Therefore, the CPU 32 set the target frequency ft to a rational number multiple of the electrical angular frequency. Then, the target angular velocity ω*0 was corrected 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.

[0056] <Second Embodiment> The second embodiment will be described below, focusing on the differences from the first embodiment, with reference to the drawings.

[0057] Figure 5 shows the configuration of the arithmetic circuit 36 ​​according to this embodiment. In Figure 5, for convenience, the same reference numerals are used for circuits corresponding to the circuit shown in Figure 3. As shown in Figure 5, the arithmetic circuit 36 ​​does not include an AD converter 50. Digital data converted from an analog signal by the AD converter 38 is input to the arithmetic circuit 36.

[0058] The AD converter 38 inputs digital data to the arithmetic circuit 36 ​​at a period equal to the reciprocal of the sampling frequency fs set in the register 74. <Third Embodiment> The third embodiment will be described below, focusing on the differences from the first embodiment, with reference to the drawings.

[0059] Figure 6 shows the configuration of the air conditioning system according to this embodiment. In Figure 6, the same reference numerals are used for the same components as those shown in Figure 1 for convenience. As shown in Figure 6, the control device 30 according to this embodiment includes a plurality of arithmetic circuits 36(1) to 36(s). Here, s is an integer of 2 or more.

[0060] Furthermore, in this embodiment, Fourier coefficients are used to suppress torque ripple caused by spatial harmonics of the motor 14. Figure 7 shows the process executed by the CPU 32. In Figure 7, for convenience, the same reference numerals are used for processes corresponding to those shown in Figure 2.

[0061] As shown in Figure 7, the deviation calculation process M16 in this embodiment inputs the deviation between the target angular velocity ω* set by the target angular velocity setting process M10 and the angular velocity ωm to the current command value setting process M18.

[0062] Phase correction process M30a calculates a correction amount Δδ to correct the phase δ of the output voltage 16 in order to suppress torque ripple caused by spatial harmonics. Correction process M12a is a process that inputs the value obtained by correcting the phase δ set by voltage command value setting process M26 with the correction amount Δδ to the operation signal generation process M28.

[0063] The phase correction process M30a is a process that calculates a correction amount Δδ based on two Fourier amplitudes Vft(1) and Vft(2) as input variables. The target frequencies ft(1) and ft(2) corresponding to the Fourier amplitudes Vft(1) and Vft(2) are both multiples of 3 of the angular velocity ωm. More specifically, the target frequencies ft(1) and ft(2) are multiples of 3 of the electrical angular frequency of the motor 14.

[0064] Figure 8 shows the procedure for setting register 74. In Figure 8, the same step numbers are assigned to the processes corresponding to those shown in Figure 4 for convenience. In the series of processes shown in Figure 8, after completing the process in S10, the CPU 32 assigns "1" to the variable i that identifies the target frequency ft (S20). Then the CPU 32 assigns the value obtained by multiplying the angular velocity ωm by the coefficient Kt(i) to the target frequency ft(i) (S12a). The coefficient Kt(i) is a multiple of 3. The CPU 32 executes the processes S14a to S18a, which correspond to the processes in S14 to S18 in Figure 4, for the target frequency ft(i). Then the CPU 32 determines whether the variable i is "2" or not (S22). If the CPU 32 determines that it is "1" (S22: NO), it increments the value of the variable i (S24) and returns to the process in S12a.

[0065] On the other hand, if the CPU 32 determines that the variable i is "2" (S22: YES), it terminates the series of processes shown in Figure 8. Now, the operation of the arithmetic circuit 36(1) corresponding to the process in Figure 8 will be explained. In the following, we will use as an example the case where the target frequency ft is 1620 Hz, the resolution is "1 Hz", the sampling frequency fs(1) is "100,000 Hz", and the number of operations N(1) is 100,000.

[0066] In this case, the AD converter 50 converts the input voltage Vin into digital data at a period of 1 / 100000. Meanwhile, the sine function value calculation unit 64 and the cosine function value calculation unit 66 set the specified variable k to "1620" because the target frequency ft is 1620 Hz. The sine function value calculation unit 64 and the cosine function value calculation unit 66 then update the counter m at a period of 1 / 100000. The integration processing units 68 and 70 output the integrated value to the Fourier amplitude calculation unit 72 each time the output values ​​of the multiplication units 60 and 62 are updated 1620 times. As a result, the Fourier amplitude Vft(1) corresponding to the target frequency ft(1) is calculated.

[0067] According to the embodiment described above, in addition to the effects similar to (1-1) to (1-3) of the first embodiment, the following further effects can be obtained: (3-1) Multiple calculation circuits 36 are provided. This makes it possible to calculate the Fourier amplitudes corresponding to each of the target frequencies ft simultaneously, even when there are multiple target frequencies ft.

[0068] (3-2) The spatial harmonics of the motor 14 tend to show a prominent frequency component at 3n times the electrical angular frequency. Therefore, the CPU 32 set the target frequency ft to a multiple of 3 of the electrical angular frequency. This suppresses the decrease in controllability of the controllable variable of the rotating electric machine caused by spatial harmonics.

[0069] <Fourth Embodiment> The fourth embodiment will be described below, focusing on the differences from the third embodiment, with reference to the drawings.

[0070] In this embodiment, the Fourier coefficient is included as an input variable for the diagnostic process to determine whether or not there is an abnormality in the compressor 12. That is, if the Fourier amplitude Oft of the target frequency ft related to the detection signal O from the vibration sensor 42 is greater than or equal to a threshold, it is determined that there is an abnormality in the compressor 12.

[0071] The target frequency ft is, for example, an integer multiple or fraction of the angular velocity ωm. The target frequency ft may also be one of the following: 1 / 3, 1 / 2, 1, 2, or 3 times the angular velocity ωm.

[0072] In this embodiment, we show an example where there is only one target frequency ft for diagnosing the presence or absence of an abnormality. However, it is assumed that the time required to calculate the Fourier coefficients of the target frequency ft is longer than the period required for the diagnosis result of the presence or absence of an abnormality. Therefore, in this embodiment, the period for updating the Fourier coefficients is shortened by staggering the start timing of the calculation of the Fourier coefficients by each of the multiple arithmetic circuits 36(1), 36(2), ...

[0073] Figure 9 shows the procedure for diagnosing whether or not there is an abnormality. The series of processes shown in Figure 9 are realized by the CPU 32 repeatedly executing a program stored in memory 34, for example, at a predetermined cycle.

[0074] In the series of processes shown in Figure 9, the CPU 32 obtains the Fourier amplitude Off(j) (S40). Here, the variable j is a variable used to identify which output it is from the arithmetic circuits 36(1), 36(2), ... The CPU 32 determines whether the Fourier amplitude Off(i) is greater than or equal to the threshold Offth (S42). If the CPU 32 determines that the Fourier amplitude Off(i) is greater than or equal to the threshold Offth (S42: YES), it determines that there is an abnormality (S44). On the other hand, if the CPU 32 determines that the Fourier amplitude Off(i) is less than the threshold Offth (S42: NO), it assigns the remainder of the value obtained by incrementing the variable j by 1 and dividing by s to the variable j (S46).

[0075] When the CPU 32 completes the processes in S44 and S46, it terminates the series of processes shown in Figure 9. Below, as an example, the operation of the arithmetic circuit 36 ​​is shown for an example where the target frequency ft is 40.5 Hz, the resolution is 0.1 Hz, the sampling frequency fs is 1000 Hz, and the number of calculations is 10000.

[0076] In this case, the AD converter 50 converts the detection signal O into digital data at a period of 1 / 1000. Meanwhile, the sine function value calculation unit 64 and the cosine function value calculation unit 66 set the specified variable k to "405" because the target frequency ft is 40.5 Hz. The sine function value calculation unit 64 and the cosine function value calculation unit 66 then update the counter m at a period of 1 / 1000. The integration processing units 68 and 70 then update the integrated value at a period of 1 / 1000. After performing 10,000 integration processes, the integration processing units 68 and 70 output the integrated value to the Fourier amplitude calculation unit 72. This calculates the Fourier amplitude Oft at a frequency of 40.5 Hz.

[0077] Incidentally, the period for updating the Fourier amplitude Off by one arithmetic circuit 36 ​​is 10 seconds. Therefore, if there is a requirement to repeatedly perform a diagnosis of whether or not there is an abnormality with a 1-second period, for example, ten arithmetic circuits 36 are prepared. Then, the timing at which each of the ten arithmetic circuits 36 updates the Fourier amplitude Off is shifted by one second. This can be achieved by shifting the timing of the command to each of the ten arithmetic circuits 36 to calculate the Fourier amplitude Off by one second.

[0078] As a result, by executing the process in Figure 9 at a 1-second interval, the CPU 32 can calculate the latest abnormality diagnosis result every second. <Correspondence> The correspondence between the matters in the above embodiment 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 viewpoint described in the "Means for Solving the Problems" section. [1] The control device corresponds to the control device 30. The software processing circuit corresponds to the CPU 32. The hardware processing circuit corresponds to the arithmetic circuit 36 ​​in Figure 1 and the arithmetic circuit 36 ​​and AD converter 38 in Figure 5. The Fourier transform circuit corresponds to the DFT circuit 55. The frequency identification data corresponds to the data indicating the target frequency ft. The coefficient data corresponds to the Fourier amplitude Ift, the Fourier amplitude Vft, and the Fourier amplitudes Oft(1), Oft(2), Oft(3),... The predetermined conditions under which the frequency identification data is changed correspond to the conditions under which the value of the angular velocity ωm obtained by the processing in S10 is changed. The conversion data corresponds to the q-axis current, input voltage Vin, and detection signal O. The predetermined processing corresponds to the vibration suppression processing in Figure 2. The predetermined processing corresponds to the spatial harmonic suppression processing in Figure 5. The predetermined processing corresponds to the abnormality diagnosis processing in Figure 9. [2] The first Fourier transform circuit corresponds to the DFT circuit 55 provided in the arithmetic circuit 36(1). The second Fourier transform circuit corresponds to the DFT circuit 55 provided in the arithmetic circuit 36(2). The first frequency identification data corresponds to the data indicating the target frequency ft(1). The second frequency identification data corresponds to the data indicating the target frequency ft(2). [3] The "predetermined phase" corresponds to "2・π・k・m / N". The first integrated value corresponds to the value integrated by the integration processing unit 68. The second integrated value corresponds to the value integrated by the integration processing unit 70. [4] The second AD converter corresponds to the AD converter 38. [5] The resolution specification data corresponds to the sampling frequency fs and the number of calculations N. [6] The rotating electric machine corresponds to the motor 14. [7] The frequency specification process corresponds to the processes of S18 and S18a. The output voltage adjustment process corresponds to the process shown in Figure 2 and the process shown in Figure 7. [8] The frequency specification process corresponds to the process of S18a. [9, 10] The diagnostic process corresponds to the process shown in Figure 9.The first Fourier transform circuit corresponds to the DFT circuit 55 provided in the arithmetic circuit 36(1). The second Fourier transform circuit corresponds to the DFT circuit 55 provided in the arithmetic circuit 36(2).

[0079] <Other Embodiments> This embodiment can be implemented with the following modifications. This embodiment and the following modifications can be combined with each other to the extent that they do not contradict each other technically.

[0080] "Regarding a configuration with multiple Fourier transform circuits" - A configuration with multiple Fourier transform circuits is not limited to being used for torque ripple suppression processing caused by spatial harmonics or for abnormality diagnosis processing. For example, it may be used for both torque ripple suppression processing and abnormality diagnosis processing. Also, for example, when the pulsating component of the load torque applied by the compressor 12 to the rotating shaft 14a of the motor 14 has multiple frequency components, it may be used for a process that controls the torque of the motor 14 based on the Fourier coefficients relating to two or more of those frequencies.

[0081] "Regarding the output of a Fourier transform circuit": It is not essential that the output of a Fourier transform circuit be only the amplitude of the target frequency component. The output of a Fourier transform circuit may be, for example, both the amplitude and phase of the target frequency component.

[0082] Regarding the arithmetic circuit: It is not essential that the arithmetic circuit 36 ​​includes a q-axis current calculation unit 54. Furthermore, it is not essential that the q-axis current iq input to the DFT circuit 55 is a value calculated by a hardware processing circuit. For example, the q-axis current iq input to the DFT circuit 55 may be a value calculated by the CPU 32.

[0083] "Regarding the conversion data" - The conversion data for the motor 14's current is not limited to the q-axis current iq. The conversion data for the motor 14's current may be, for example, the d-axis current id. The conversion data for the motor 14's current may be, for example, the current I. Also, for example, the conversion data for the motor 14's current may be the output line current of the inverter 16. Also, for example, the conversion data for the motor 14's current may be the α-phase current or β-phase current obtained by two-phase conversion of the output line current of the inverter 16. The conversion data for the motor 14's current may be, for example, the M-axis current or T-axis current obtained by coordinate transformation based on the angle of the primary magnetic flux of the motor 14. Note that the coordinate transformation used to generate the conversion data for the motor 14's current is not limited to those exemplified above.

[0084] The conversion data for the motor 14's current does not necessarily have to be data for a current that fluctuates moment by moment. The conversion data for the motor 14's current may be, for example, a quantity proportional to the amplitude of the output line current, α-phase current, or β-phase current, or the square of the same quantity. Alternatively, for example, the conversion data for the motor 14's current may be a quantity relating to the difference between the maximum and minimum values ​​of the q-axis current or d-axis current.

[0085] The conversion data for the motor 14 voltage is not limited to the input voltage Vin. The conversion data for the motor 14 voltage may be, for example, the output line voltage of the inverter 16. Alternatively, the conversion data for the motor 14 voltage may be the d-axis voltage or the q-axis voltage. The coordinate transformation used to generate the conversion data for the motor 14 voltage is not limited to a coordinate transformation to the d and q axes.

[0086] The conversion data for the motor 14 voltage does not necessarily have to be voltage data that fluctuates moment by moment. The conversion data for the motor 14 voltage may be a quantity proportional to the amplitude of the output line voltage, or the square of the same quantity. For example, the conversion data for the motor 14 voltage may be a quantity relating to the difference between the maximum and minimum values ​​of the d-axis voltage or the q-axis voltage.

[0087] The conversion data may be, for example, the instantaneous power of the motor 14. The conversion data related to power may be, for example, instantaneous imaginary power, apparent power, active power, or reactive power.

[0088] - The conversion data may be, for example, the armature flux linkage. The conversion data related to magnetic flux may be, for example, the d-axis magnetic flux or the q-axis magnetic flux. - The conversion data may also be, for example, physical quantities estimated using a physical model based on sensor detection values, such as magnetic pole position or motor 14 torque.

[0089] - The analog signal used to generate the digital data for conversion may be, for example, a magnetic pole position signal obtained from an encoder or the like. Alternatively, the analog signal used to generate the digital data for conversion may be a sound signal obtained from a sound sensor that senses the sound around the motor 14. Alternatively, the analog signal used to generate the digital data for conversion may be a temperature signal obtained from a temperature sensor that senses the temperature around the motor 14.

[0090] "Regarding variables that are changed according to frequency-specific data": In the above embodiment, both the sampling frequency fs and the number of operations N can be changed according to the frequency-specific data, but this is not limited to this. For example, the number of operations N may be fixed.

[0091] "Regarding countermeasures for load torque pulsation" - It is not essential that the manipulated variable for the load torque suppression process is the correction amount Δωc of the target angular velocity ω*. The manipulated variable for the load torque suppression process may be, for example, either the amplitude Va or the phase δ of the output voltage of the inverter 16.

[0092] The Fourier coefficients used as input for the processing to address load torque pulsation are not limited to Fourier coefficients for a single frequency. The Fourier coefficients used as input for the processing to address load torque pulsation may be Fourier coefficients for multiple different frequencies.

[0093] "Regarding Torque Ripple Suppression Processing Caused by Spatial Harmonics" - It is not essential that the torque ripple suppression processing caused by spatial harmonics calculates a manipulated variable for suppressing torque ripple based on the Fourier coefficients of two distinct harmonics. For example, the torque ripple suppression processing caused by spatial harmonics may calculate a manipulated variable for suppressing torque ripple based on the Fourier coefficient of a single harmonic. Alternatively, for example, the torque ripple suppression processing caused by spatial harmonics may calculate a manipulated variable for suppressing torque ripple based on the Fourier coefficients of three distinct harmonics.

[0094] - It is not essential that the manipulated variable for torque ripple suppression due to spatial harmonics be the phase δ. The manipulated variable for torque ripple suppression due to spatial harmonics may be, for example, the amplitude Va of the output voltage of the inverter 16. Alternatively, for example, the manipulated variable for torque ripple suppression due to spatial harmonics may be the correction amount of the target angular velocity ω*.

[0095] Regarding output voltage adjustment processing: The dq-axis current feedback processing is not limited to processing using PD control. The dq-axis current feedback processing may, for example, use PID control. Furthermore, the dq-axis current feedback processing is not limited to classical control; for example, model predictive control may also be used.

[0096] - It is not mandatory for the output voltage adjustment process to include current feedback processing for the dq axis. For example, the output voltage adjustment process may be related to direct torque control.

[0097] Regarding the control variable of motor 14: It is not essential that the control variable of motor 14 be angular velocity ω. The control variable of motor 14 may be, for example, the torque of motor 14.

[0098] Regarding the hardware processing circuit: The arithmetic circuit 36 ​​does not need to include an electrical angle calculation unit 52 and a q-axis current calculation unit 54; the CPU 32 may perform the processing that the electrical angle calculation unit 52 and the q-axis current calculation unit 54 would perform.

[0099] - It is not essential that the arithmetic circuit 36 ​​be integrated into a single chip separate from the CPU 32, memory 34, AD converter 38, etc. - It is not essential that the Fourier transform circuit is a circuit that performs sequential integration processing for each value obtained by multiplying the transformation data by "sin(2・π・k・m / N)" and "cos(2・π・k・m / N)" each time transformation data is generated. For example, it may be a circuit that executes the Cooley-Tukey type FFT algorithm.

[0100] Regarding rotating electric machines: The rotating electric machine is not limited to the motor 14 that drives the compressor 12. For example, it could be a motor mounted on a circulator.

[0101] Regarding the motor: The motor is not limited to embedded magnet synchronous motors; for example, an induction motor may also be used. Furthermore, the motor may be a brushed DC motor.

[0102] Regarding software processing circuits: It is not mandatory for a software processing circuit to be a CPU. For example, a software processing circuit may include both a CPU and a GPU.

[0103] Regarding the control device: The control object of the control device is not limited to the motor 14 that drives the compressor 12. As described above, the embodiments can be modified in various ways and details without departing from the spirit and scope of the claims.

[0104] 10...Air conditioning system 12...Compressor 14...Motor 30...Control device

Claims

1. A control device for controlling a control variable of a controlled object, comprising: a software processing circuit (32) and a hardware processing circuit (36), wherein the hardware processing circuit (36) comprises: an AD converter (50) for converting an analog signal into digital data and a Fourier transform circuit (55) for converting the conversion data into coefficient data, wherein when frequency-specific data is input from the software processing circuit (32) to the hardware processing circuit (36), the hardware processing circuit (36) is configured to output coefficient data calculated using at least one of two factors: a sampling frequency and an operation count corresponding to the frequency-specific data which are changed under predetermined conditions, to the software processing circuit (32), wherein the conversion data is the digital data or data calculated from the digital data, the frequency-specific data is data for determining the frequency for which the Fourier coefficients are to be obtained, the coefficient data is data indicating the Fourier coefficients of the frequency specified by the frequency-specific data, and the software processing circuit (32) is configured to perform predetermined processing relating to the controlled object based on the coefficient data as an input variable.

2. The control device according to claim 1, wherein the Fourier transform circuit (55) includes a first Fourier transform circuit and a second Fourier transform circuit, the software processing circuit (32) is configured to input the first frequency-specific data as frequency-specific data to the first Fourier transform circuit and to input the second frequency-specific data as frequency-specific data to the second Fourier transform circuit, the first Fourier transform circuit is configured to output to the software processing circuit (32) the coefficient data calculated using at least one of the first frequency-specific data when the first frequency-specific data is input, and the second Fourier transform circuit is configured to output to the software processing circuit (32) the coefficient data calculated using at least one of the second frequency-specific data when the second frequency-specific data is input.

3. The control device according to claim 1 or 2, wherein the Fourier transform circuit (55) is configured to perform a process to generate a first integrated value obtained by multiplying the value indicated by the corresponding conversion data by the value of a sine function of a predetermined phase and integrating the results, and a second integrated value obtained by multiplying the value of a cosine function of a predetermined phase and integrating the results, each time the analog signal is converted to digital data by the AD converter (50).

4. The control device according to any one of claims 1 to 3, wherein the AD converter (50) is a first AD converter, and the control device comprises a second AD converter (38) separate from the first AD converter, and is configured such that the digital data output by the second AD converter (38) is input to the software processing circuit (32).

5. The control device according to any one of claims 1 to 4, wherein the software processing circuit (32) is configured to input resolution specification data to the hardware processing circuit (36), and the resolution specification data is data that specifies at least one corresponding to the frequency specification data.

6. The control device according to any one of claims 1 to 5, wherein the controlled object is a rotating electric machine (14).

7. The control device according to claim 6, wherein the rotating electric machine (14) is a motor (14) that drives a compressor (12), the terminals of the motor (14) are configured to receive the output voltage of an inverter, the software processing circuit (32) is configured to perform frequency specification processing and output voltage adjustment processing, the frequency specification processing is a process of inputting data relating to frequencies that are rational multiples of the mechanical angular frequency of the motor (14) to the hardware processing circuit (36) as frequency specification data, and the output voltage adjustment processing is a process of manipulating the output voltage of the inverter based on the coefficient data as an input variable.

8. The control device according to claim 6 or 7, wherein the output voltage of the inverter (16) is applied to the terminals of the rotating electric machine (14), the software processing circuit (32) is configured to perform frequency specification processing and output voltage adjustment processing, the frequency specification processing is a process of inputting data relating to a frequency that is 3n times the electrical angular frequency of the rotating electric machine (14) (where n is a natural number of 1 or more) as frequency specification data to the hardware processing circuit (36), and the output voltage adjustment processing is configured to operate the output voltage of the inverter (16) based on the coefficient data as an input variable.

9. The control device according to any one of claims 6 to 8, wherein the software processing circuit (32) is configured to perform frequency specification processing and diagnostic processing, the frequency specification processing is a process of inputting data relating to frequencies that are rational multiples of the mechanical angular frequency of the rotating electric machine (14) as frequency specification data to the hardware processing circuit (36), and the diagnostic processing is a process of diagnosing whether or not there is an abnormality in the controlled object based on the coefficient data.

10. The control device according to claim 9, wherein the Fourier transform circuit (55) includes a first Fourier transform circuit and a second Fourier transform circuit, the software processing circuit (32) is configured to input the same frequency-specific data to both the first Fourier transform circuit and the second Fourier transform circuit, and the first Fourier transform circuit and the second Fourier transform circuit are configured to output coefficient data corresponding to time-series data of different digital data, using the digital data output by the AD converter (50) at different sampling timings as the initial input data.

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