Control device, control method, and air conditioner

Abstract

A control device according to the present invention controls an inverter that performs AC driving of a motor which rotates and drives a compressor, thereby controlling the rotational speed of the motor. The control device corrects a torque command value, which is calculated according to a deviation between the rotational speed of the motor and a rotational speed command value on the basis of any one of a plurality of patterns to correspond to the load fluctuations of the compressor, and, when controlling the inverter on the basis of the corrected torque command value, recognizes an extreme value of a first polarity and two extreme values ​​of a second polarity different from the first polarity, the extreme values being included in a deviation waveform during a rotation of the compressor, and selects any one of the plurality of patterns on the basis of pieces of information, which are used in control of the motor and respectively obtained at timings when the plurality of extreme values ​​occurred.

Description

Control device, control method, and air conditioner

[0001] The present disclosure relates to a control device, a control method, and an air conditioner.

[0002] In a rotary compressor, steady load torque fluctuations occur due to changes in refrigerant gas pressure during each of the suction, compression, and discharge strokes during one rotation. The control device described in Patent Document 1 suppresses motor speed fluctuations by compensating the output torque command based on the estimated rotor position using the product of the average torque and a normalized torque pattern. The normalized torque pattern described in Patent Document 1 is a pattern of coefficient values ​​set, for example, every 30 degrees of rotation of the motor rotor. The coefficient values ​​for each section are normalized so that the product of the average torque and the coefficient values ​​for each section equals the average torque in total across all sections. Furthermore, when multiple normalized torque patterns are prepared, this control device selects a normalized torque pattern based on the average load torque driving the motor, the motor rotation speed fluctuation range, the peak value of the motor current, or the rotor angle at which the motor rotation speed peaks.

[0003] Japanese Patent Application Laid-Open No. 2008-245506

[0004] According to the control device described in Patent Document 1, as described above, a normalized torque pattern corresponding to the rotational state is selected from among a plurality of normalized torque patterns, and the selected normalized torque pattern is used to compensate the output torque command in accordance with the estimated rotor position, thereby suppressing motor speed fluctuations.

[0005] The present disclosure has been made against the background of the above technology, and aims to provide a control device, a control method, and an air conditioner that are capable of appropriately selecting a pattern.

[0006] A control device according to the present disclosure is a control device that controls the rotation speed of a motor by controlling an inverter that drives an AC motor to rotate a compressor, and corrects a torque command value calculated in accordance with a deviation between the rotation speed of the motor and a rotation speed command value based on one of a plurality of patterns for responding to load fluctuations of the compressor. When controlling the inverter based on the corrected torque command value, the control device recognizes one extreme value of a first polarity and two extreme values ​​of a second polarity different from the first polarity included in a waveform of the deviation during one rotation of the compressor, and selects one of the plurality of patterns based on information used for controlling the motor obtained at each timing when the multiple extreme values ​​occur. According to this aspect and each of the following aspects, it is possible to appropriately select a pattern.

[0007] A control method according to the present disclosure is a method for controlling the rotation speed of a motor by controlling an inverter that AC drives the motor that rotates a compressor, the method comprising: correcting a torque command value calculated in accordance with a deviation between the rotation speed of the motor and a rotation speed command value based on one of a plurality of patterns for dealing with load fluctuations on the compressor; and, when controlling the inverter based on the corrected torque command value, recognizing one extreme value of a first polarity and two extreme values ​​of a second polarity different from the first polarity that are included in the waveform of the deviation during one rotation of the compressor; and selecting one of the plurality of patterns based on information used in control of the motor obtained at each timing when the plurality of extreme values ​​occur.

[0008] The air conditioner according to the present disclosure comprises a compressor, a motor that drives the compressor to rotate, an inverter that drives the motor with AC, and a control device that controls the inverter to control the rotation speed of the motor, the control device correcting a torque command value calculated in accordance with the deviation between the rotation speed of the motor and a rotation speed command value based on one of a plurality of patterns for responding to load fluctuations of the compressor, and when controlling the inverter based on the corrected torque command value, recognizing one extreme value of a first polarity and two extreme values ​​of a second polarity different from the first polarity contained in the waveform of the deviation during one rotation of the compressor, and selecting one of the plurality of patterns based on information used in control of the motor obtained at each timing when the plurality of extreme values ​​occur.

[0009] According to the control device, control method, and air conditioner of the present disclosure, it is possible to appropriately select a pattern.

[0010] FIG. 1 is a block diagram showing an example configuration of a control device for a motor connected to an air conditioning rotary compressor according to the first embodiment of the present disclosure. FIG. 2 is a block diagram showing an example configuration of a load torque compensation unit according to the first embodiment of the present disclosure. FIG. 3 is a schematic diagram showing an example of a normalized torque pattern according to the first embodiment of the present disclosure. FIG. 4 is a schematic diagram showing an example of a normalized torque pattern multiplied by a modulation factor according to the first embodiment of the present disclosure. FIG. 5 is a block diagram showing an example configuration of a normalized torque pattern selection unit according to the first embodiment of the present disclosure. FIG. 6 is a schematic diagram for explaining an example operation of the normalized torque pattern selection unit according to the first embodiment of the present disclosure. FIG. 7 is a schematic diagram for explaining an example operation of the normalized torque pattern selection unit according to the first embodiment of the present disclosure. FIG. 8 is a schematic diagram for explaining torque compensation according to the first embodiment of the present disclosure. FIG. 9 is a schematic diagram for explaining torque compensation according to the first embodiment of the present disclosure. Fig. 1 is a schematic diagram for explaining torque compensation according to a first embodiment of the present disclosure; Fig. 2 is a schematic diagram for explaining torque compensation according to the first embodiment of the present disclosure; Fig. 3 is a block diagram for explaining a configuration example of a pattern switching determination unit according to a second embodiment of the present disclosure; Fig. 4 is a schematic block diagram showing a configuration of a computer according to at least one embodiment;

[0011] A control device, a control method, and an air conditioner according to embodiments of the present disclosure will be described below with reference to FIGS. 1 to 20 . FIG. 1 is a block diagram showing an example configuration of a control device for a motor connected to an air conditioning rotary compressor according to a first embodiment of the present disclosure. FIG. 2 is a block diagram showing an example configuration of a load torque compensation unit according to a first embodiment of the present disclosure. FIG. 3A is a schematic diagram showing an example of a normalized torque pattern according to a first embodiment of the present disclosure. FIG. 3B is a schematic diagram showing an example of a normalized torque pattern multiplied by a modulation factor according to a first embodiment of the present disclosure. FIG. 4 is a schematic diagram showing an example of load torque compensation control according to a first embodiment of the present disclosure. FIG. 5 is a block diagram showing an example configuration of a normalized torque pattern selection unit according to a first embodiment of the present disclosure. FIGS. 6 to 8 are schematic diagrams for explaining an example operation of the normalized torque pattern selection unit according to a first embodiment of the present disclosure. FIGS. 9 to 18 are schematic diagrams for explaining torque compensation according to a first embodiment of the present disclosure. FIG. 19 is a block diagram showing an example configuration of a pattern switching determination unit according to a second embodiment of the present disclosure. FIG. 20 is a schematic block diagram showing the configuration of a computer according to at least one embodiment. In addition, the same or corresponding components in each drawing are designated by the same reference numerals, and the description thereof will be omitted as appropriate.

[0012] First Embodiment FIG. 1 shows a configuration example of a control device 1 according to a first embodiment of the present disclosure. The control device 1 controls an inverter 4 that drives an AC motor 2, which in turn drives a compressor 5 included in an air conditioner 100, thereby controlling the rotation speed (i.e., the rotational speed) of the motor 2. The inverter 4 uses an AC power supply 3 as a power source to supply power to the motor 2. A current sensor 10 detects the value of a current passed from the inverter 4 to the motor 2. In the example shown in FIG. 1 , the air conditioner 100 includes the control device 1, the motor 2, the inverter 4, and the current sensor 10. The control device 1 includes a computer, such as a microcontroller, and peripheral devices and circuits for the computer. The control device 1 also includes a subtraction unit 14, a speed control unit 20, a load torque compensation unit 13, a normalized torque pattern selection unit 26, a speed / position estimation unit 11, a two-phase / three-phase conversion unit 21, and a three-phase / two-phase conversion unit 22 as a functional configuration formed by a combination of hardware, such as a computer, and software, such as a program executed by the computer. The speed control unit 20 includes a speed PI control unit (speed proportional integral control unit) 12 , an adder 15 , a current converter 16 , a subtractor 17 , and a current PI control unit 18 .

[0013] The control device according to this embodiment is not limited to the example shown in Fig. 1, but may be any control device that controls a motor that drives a compressor such as a rotary compressor. The compressor is not limited to that provided in an air conditioner. Fig. 1 shows the main components related to the control of the rotation speed of the motor 2 by the control device 1, and does not illustrate some other components of the air conditioner 100 or the control device 1, such as the refrigerant circuit, the fan, and temperature sensors related to temperature and humidity control.

[0014] The three-phase / two-phase converter 22 receives the three-phase current values ​​I detected by the current sensor 10 and the rotational position (rotation angle) θes of the rotor of the motor 2 estimated by the speed / position estimator 11, converts the three-phase current values ​​I detected by the current sensor 10 into a d-axis current value id and a q-axis current value iq for two phases, the d-axis and q-axis, and outputs them. The two-phase / three-phase converter 21 receives the rotational position θes and the d-axis command voltage value vd* and the q-axis command voltage value vq* for two phases, the d-axis and q-axis, output by the current PI control unit 18, converts them into three-phase voltage values ​​V, and outputs them to the inverter 4. The inverter 4 controls a plurality of switching elements (not shown) provided in the inverter based on the three-phase voltage values ​​V output by the two-phase / three-phase converter 21.

[0015] The speed / position estimation unit 11 estimates the rotational position θes and rotational speed ωes of the rotor of the motor 2 based on the two-phase d-axis voltage value vd and q-axis voltage value vq output by the current PI control unit 18 and the two-phase d-axis current value id and q-axis current value iq output by the three-phase / two-phase conversion unit 22.

[0016] The subtraction unit 14 subtracts the rotation speed ωes from the rotation speed command value ω* to calculate a deviation Δω (also called a speed fluctuation value Δω), and outputs it to the speed PI control unit 12 and the normalized torque pattern selection unit 26 .

[0017] The speed PI control unit 12 calculates an average torque command value τa*, which is the average value of the output torque command values ​​τ* of the motor 2 for reducing the deviation Δω by proportional-plus-integral action with respect to the deviation Δω, and outputs the calculated average torque command value τa* to the adder 15 and the load torque compensator 13. In this case, the speed PI control unit 12 calculates and outputs the average torque command value τa* in accordance with the deviation Δω between the rotation speed ωes of the motor 2 and the rotation speed command value ω*.

[0018] Load torque compensation unit 13 receives as input the average torque command value τa* output by speed PI control unit 12, the rotational position θes and rotational speed ωes output by speed / position estimator 11, and the pattern switching command output by normalized torque pattern selector 26, calculates a compensation torque value, and outputs it to adder 15. The compensation torque value is a torque value for compensating for fluctuations in the load torque of motor 2 during one rotation of motor 2. FIG. 2 shows an example configuration of load torque compensation unit 13. Load torque compensation unit 13 shown in FIG. 2 includes a load torque compensation control unit 131, a compensation torque value calculation unit 132, and a normalized torque pattern storage unit 133.

[0019] The normalized torque pattern storage unit 133 stores a plurality of normalized torque patterns, which are patterns of a plurality of coefficient values ​​that change according to the rotational position (rotational angle) θes of the motor 2. In this embodiment, as shown in FIG. 3A , the normalized torque pattern storage unit 133 stores 13 normalized torque patterns (hereinafter also referred to as torque patterns or patterns) TP1 to TP13. Each of the patterns TP1 to TP13 is a pattern for responding to load fluctuations on the compressor 5 and corresponds to a plurality of different pressure ratios of the compressor 5. The pressure ratio is the value obtained by dividing the discharge pressure (absolute pressure) of the compressor 5 by the suction pressure (absolute pressure). In the example shown in FIG. 3A , the pressure ratio of pattern TP1 is the smallest, and the pressure ratios of patterns TP1 to TP13 increase in the order of patterns TP1 to TP13 at predetermined intervals, with pattern TP13 having the largest pressure ratio. 3A, the horizontal axis corresponds to the rotational position (mechanical angle) of one rotation of the motor 2 from 0° to 360°, and the vertical axis corresponds to the load torque of the motor 2 (driving torque of the compressor 5). Furthermore, each of the patterns TP1 to TP13 is normalized so that the average load torque per rotation is the same.

[0020] The compensation torque value calculation unit 132 selects one of the patterns TP1 to TP13 based on the pattern switching command output by the normalization torque pattern selection unit 26, and calculates a compensation torque value based on the selected pattern TP1 to TP13. The selection of one of the patterns TP1 to TP13 is performed in the order of the magnitude of the pressure ratio in the direction of increasing or decreasing the pressure ratio. For example, if the currently selected pattern is pattern TP1, and a pattern switching command (UP) instructing an increase in the pressure ratio is input, the compensation torque value calculation unit 132 selects pattern TP2. Also, if the currently selected pattern is pattern TP1, and a pattern switching command (DOWN) instructing a decrease in the pressure ratio is input, the compensation torque value calculation unit 132 selects pattern TP1 as is. Also, if the currently selected pattern is pattern TP13, and a pattern switching command (UP) instructing an increase in the pressure ratio is input, the compensation torque value calculation unit 132 selects pattern TP13 as is.

[0021] The compensation torque value calculation unit 132 determines a coefficient value according to the rotational position (rotational angle) θes of the motor 2 based on one of the normalized torque patterns TP1 to TP13, multiplies the determined coefficient value by the average torque command value τa*, and then multiplies this by a predetermined modulation factor to calculate a compensation torque value. The modulation factor is a coefficient for adjusting the degree of torque compensation. The compensation torque value and the coefficient value can be positive, negative, or zero. In this case, the compensation torque value calculation unit 132 calculates the compensation torque value at each rotational position using the formula (compensation torque value at each rotational position = average torque command value τa* × normalized torque pattern at each rotational position × modulation factor). FIG. 3B shows example values ​​of (normalized torque pattern × modulation factor) when the modulation factor is 75% (solid line) and 100% (dashed line). The value of (normalized torque pattern × modulation factor) is calculated by multiplying the modulation factor for each positive and negative value, with zero as the reference. By adding the compensation torque value calculated by the above formula to the average torque command value τa*, an output torque command value τ* (output value of the adder 15) is calculated, in which the load torque fluctuation is compensated for according to the rotational position θes. The compensation torque value is a value that compensates for the load torque fluctuation during one rotation. The average value of the output torque command value for one rotation compensated by the compensation torque value is required to match the average torque command value τa*. That is, the total value of the compensation torque value for one rotation is required to be zero. In this case, the total value of the coefficient values ​​constituting (defining) the normalized torque pattern for one rotation is also required to be zero. The compensation torque value calculation unit 132 may calculate the compensation torque value after offsetting the rotational angle θes of the motor 2 by a predetermined value. That is, the compensation torque value calculation unit 132 can calculate the compensation torque value based on the rotational angle θes after phase adjustment by a predetermined value. In this case, the magnitude of the phase adjustment may be a predetermined fixed value or may be a variable value depending on, for example, the operating state of the motor 2.

[0022] The load torque compensation control unit 131 controls the value of the compensation torque value output by the load torque compensation unit 13, for example, according to the example of control content shown in FIG. 4. In FIG. 4, the horizontal axis represents the rotational speed of the motor 2. In the example shown in FIG. 4, load torque compensation control is performed from rotational speed Na to rotational speed Nc, and load torque compensation control is not performed once rotational speed Nc is exceeded. Furthermore, automatic pattern switching control is performed from rotational speed Na to rotational speed Nb, and pattern fixed control is performed from rotational speed Nb to rotational speed Nc. When load torque compensation control is performed, the load torque compensation control unit 131 outputs the compensation torque value calculated based on the normalized torque pattern. When load torque compensation control is not performed, the load torque compensation control unit 131 sets the compensation torque value to a constant zero. In this case, the output torque command value τ* is constant at the average torque command value τa*. In addition, automatic pattern switching control is control in which the load torque compensation unit 13 outputs the torque compensation value calculated by the compensation torque value calculation unit 132 by switching the pattern to one of patterns TP1 to TP13 in accordance with a pattern switching command (UP or DOWN). In addition, in automatic pattern switching control, the load torque compensation control unit 131 sets the modulation rate to a value between 50% and 100% (for example, a constant 75%), for example. In pattern fixed control, the pattern is fixed to one of patterns TP1 to TP13 (this pattern is called a fixed pattern), and the load torque compensation unit 13 outputs the torque compensation value calculated by the compensation torque value calculation unit 132. In addition, in pattern fixed control, the load torque compensation control unit 131 sets the modulation rate to a value less than 50%, for example (since the effect of inertia comes into play, it is possible to reduce the modulation rate as the rotation speed increases, and the compensation amount is set to, for example, 50% to 30%) as the rotation speed increases). When the rotation speed exceeds Nb from below Nb, the automatic pattern switching is switched to a fixed pattern, but after the rotation speed exceeds Nb, the patterns are switched to approach the fixed pattern one by one. When the rotation speed exceeds Nb and drops below Nb, the pattern switching is switched from the fixed pattern to the automatic pattern switching, thereby switching to the optimal pattern one by one. Note that Figure 4 shows an example of control by the load torque compensation control unit 131, and the control by the load torque compensation control unit 131 is not limited to this example.

[0023] The adder 15 adds the average torque command value τa* output by the speed PI control unit 12 and the compensation torque value output by the load torque compensation unit 13 to calculate the output torque command value τ*, and outputs it to the current conversion unit 16 and the normalized torque pattern selection unit 26.

[0024] The current conversion unit 16 receives the output torque command value τ* output by the addition unit 15, converts the output torque command value τ* into a current, calculates a d-axis command current value id* and a q-axis command current value iq*, and outputs them to the subtraction unit 17.

[0025] The subtraction unit 17 receives the d-axis command current value id*, the q-axis command current value iq*, and the d-axis current value id and the q-axis current value iq, subtracts the d-axis current value id and the q-axis current value iq from the d-axis command current value id* and the q-axis command current value iq*, respectively, calculates the deviations of the d-axis component and the q-axis component between the command value and the motor current value, and outputs the deviations to the current PI control unit 18.

[0026] The current PI control unit 18 calculates a d-axis command voltage value vd* and a q-axis command voltage value vq* for reducing each deviation output by the subtraction unit 17 through proportional-plus-integral operation, and outputs the calculated values ​​to the two-phase / three-phase conversion unit 21, the speed / position estimation unit 11, and the normalized torque pattern selection unit 26.

[0027] Next, the normalized torque pattern selection unit 26 will be described with reference to Fig. 5 etc. Fig. 5 shows an example of the configuration and operation of the normalized torque pattern selection unit 26. As shown in Fig. 5 , in this embodiment, the normalized torque pattern selection unit 26 includes a torque command difference calculation unit 261, a speed fluctuation extreme value comparison unit 262, a first pattern switching determination unit 263, a second pattern switching determination unit 264, and a pattern switching determination unit 265.

[0028] The torque command difference calculation unit 261 receives the speed fluctuation value Δω, the output torque command value τ*, and the rotational position θes, and calculates and outputs a predetermined torque command difference Δτs. FIGS. 6 to 8 show examples of calculations of the torque command difference Δτs. With the horizontal axis representing the angle (rotational position θes), FIGS. 6 to 8 show examples of the correspondence between torque (load torque and motor output torque), changes in the speed fluctuation value Δω (waveform W1), and changes in the torque deviation Δτ (waveform). FIG. 6 shows a case where the motor output torque leads the load torque, FIG. 7 shows a case where the motor output torque roughly matches the load torque, and FIG. 8 shows a case where the motor output torque lags the load torque. First, the torque command difference calculation unit 261 recognizes one extreme value of a first polarity (positive maximum value P11 in FIGS. 6 to 8 ) and two extreme values ​​of a second polarity different from the first polarity (negative minimum values ​​P21 and P22 in FIGS. 6 to 8 ) included in the waveform W1 of the deviation Δω during one rotation of the compressor 5. For example, assuming that the waveform W1 of the deviation Δω always includes one maximum value P11 and two extreme values ​​P21 and P22 before and after the maximum value P11, the torque command difference calculation unit 261 first recognizes the maximum value on the waveform W1 as the maximum value P11 and the minimum values ​​before and after the maximum value P11 as the extreme values ​​P21 and P22. Note that in this embodiment, the extreme value P21 and the extreme value P22 are referred to as the minimum value (first half) and the minimum value (second half). The positive or negative sign of the deviation Δω is relative, and if the sign is reversed from that shown in the figure, the maximum value P11 may be the minimum value, and the minimum values ​​P21 and P22 may be the maximum values. Note that the extreme values ​​include the maximum value and the minimum value.

[0029] Next, the torque command difference calculation unit 261 calculates a difference Δτs between the difference Δτ (T1 in FIG. 6 , T2 in FIG. 7 , and T2 in FIG. 8 ) between the corrected torque command value (output torque command value τ*) obtained at the timing when the extreme value (P11) of the first polarity occurs and the average value of the torque command values ​​(average torque command value), and the difference Δτ (T2 in FIG. 6 , T1 in FIG. 7 , and T1 in FIG. 8 ) between the corrected torque command value (output torque command value τ*) obtained at the timing when the extreme value (P11) of the first polarity occurs, which has the larger absolute value (P22 in FIG. 6 , P21 in FIG. 7 , and P21 in FIG. 8 ) of the two extreme values ​​(P21 and P22) of the second polarity occurs and the average value of the torque command values ​​(average torque command value). Note that in this embodiment, the extreme values ​​P21 and P22 and the difference Δτs are examples of "information used in controlling the motor" according to the present disclosure. However, the "information used to control the motor" is not limited to these examples, and can be, for example, estimated values ​​or command values ​​of motor current, voltage, rotation speed, and torque, or calculated values ​​based on these values.

[0030] The first pattern switching determination unit 263 determines whether to increase or decrease the pressure ratio of the pattern based on the difference Δτs calculated by the torque command difference calculation unit 261, and outputs the determination result as a first switching command. In this embodiment, the first pattern switching determination unit 263 determines to increase (increase) the output pattern pressure ratio when Δτs > 0. Furthermore, the first pattern switching determination unit 263 determines to decrease (decrease) the output pattern pressure ratio when Δτs < 0.

[0031] In this embodiment, a switching method is adopted in which a target output pattern is selected based on the phase where the difference (Δτ) in the output torque command value at the minimum and maximum speed points reverses between positive and negative and the compressor low vibration point, utilizing the correlation between the phase where Δτ reverses between positive and negative. The control start phase, where the difference (Δτ) in the torque command value at the minimum and maximum speed fluctuation Δω reverses between positive and negative, is correlated with the minimum vibration phase. The control start phase where Δτ reverses between positive and negative varies depending on the pressure ratio of the output pattern, and the control start phase tends to increase as the pressure ratio increases. By setting the control start phase, it is possible to select an arbitrary output pattern based on the positive / negative determination of Δτ.

[0032] Meanwhile, the speed fluctuation extreme value comparison unit 262 receives the speed fluctuation value Δω and the rotational position θes and outputs a comparison result of the magnitude of each deviation Δω obtained at each timing when two extreme values ​​(P21 and P22) of the second polarity occur. In the example shown in FIGS. 6 to 8 , the speed fluctuation extreme value comparison unit 262 first recognizes, in the same manner as the torque command difference calculation unit 261, one extreme value of the first polarity (positive maximum value P11 in FIGS. 6 to 8 ) and two extreme values ​​of a second polarity different from the first polarity (negative minimum value (first half) P21 and minimum value (second half) P22 in FIGS. 6 to 8 ) included in the waveform W1 of the deviation Δω during one rotation of the compressor 5. Next, the speed fluctuation extreme value comparison unit 262 compares the magnitudes (absolute values) of the minimum value (first half) P21 and the minimum value (second half) P22.

[0033] The second pattern switching determination unit 264 determines whether to increase, decrease, or maintain the pressure ratio of the pattern based on the comparison result of the speed fluctuation extreme value comparison unit 262, and outputs the determination result as a second switching command. In this embodiment, the second pattern switching determination unit 264 determines to maintain the output pattern pressure ratio when |First Half - Second Half| < a predetermined speed fluctuation difference threshold. Here, the first half is the value of the minimum value (first half) P21, and the second half is the value of the minimum value (second half) P22. Furthermore, the second pattern switching determination unit 264 determines to increase the output pattern when the first half is greater than the second half. Furthermore, the second pattern switching determination unit 264 determines to decrease the output pattern when the first half is less than the second half.

[0034] In this embodiment, a method is adopted in which the lead / lag relationship of the output torque peak position relative to the load torque peak position is determined based on the magnitude relationship between two minimum values ​​of the estimated speed fluctuation Δω during rotation, and an output torque pattern is selected to match the load torque peak position. Focusing on the two speed minimum values ​​of the estimated speed fluctuation during one rotation, it is possible to determine whether the output torque peak position is lead / lag relative to the load torque peak position based on the magnitude relationship between the first and second halves. As shown in FIG. 3A , the output torque pattern has a characteristic in which the torque peak position advances / delays depending on whether the pressure ratio is low or high. For example, if the speed minimum of the estimated speed fluctuation is smaller in the first half than in the second half, it is determined that the output torque peak is lagging relative to the load torque peak position, and a "low pressure ratio pattern" that shifts the torque peak position to advance is selected, thereby achieving pattern matching with the load torque.

[0035] The pattern switching determination unit 265 includes a determination unit 266 and a determination stabilization unit 267. The determination unit 266 outputs a determination result of maintain, UP, or DOWN based on the first switching command and the second switching command. When the first switching command and the second switching command are both UP, the determination unit 266 determines the determination result as UP. When the first switching command and the second switching command are both DOWN, the determination unit 266 determines the determination result as DOWN. In other cases, the determination unit 266 determines the determination result as maintain.

[0036] The determination stabilization unit 267 functions as a filter for the determination result of the determination unit 266, and outputs an UP or DOWN pattern switching command when the determination result is UP or DOWN n times or more during m rotations.

[0037] (Regarding Torque Compensation) Here, with reference to FIGS. 9 to 16 , examples of the relationship between the modulation rate in torque compensation, the selected pattern, and the torque deviation will be described. FIGS. 9 to 16 show simulation results of the load torque, motor torque, and torque deviation (the difference between the load torque and the motor torque), with the horizontal axis representing the angle. FIG. 9 shows an example in which the modulation rate is 75%, a pattern is used in which the pressure ratio is increased by approximately 35% relative to the load torque, and a phase difference is 12 degrees. Here, the pattern in which the load torque is increased by approximately 35% refers to, for example, a pattern among the multiple patterns shown in FIG. 3A that does not correspond to the pressure ratio corresponding to the load torque, but rather a pattern in which the pressure ratio is increased by approximately 35%. The phase difference is a phase adjustment value, and a fixed value is used in the examples shown in FIGS. 9 to 15 . FIG. 10 shows an example in which the modulation rate is 75%, a pattern is used in which the pressure ratio is increased by approximately 60% relative to the load torque, and a phase difference is 12 degrees. FIG. 11 shows an example in which a modulation rate of 75% is used, a pattern with a pressure ratio equal to the load torque, and a phase difference of 12 degrees. FIG. 12 shows an example in which a modulation rate of 75% is used, a pattern with a pressure ratio increased by approximately 30% relative to the load torque, and a phase difference of 12 degrees. FIG. 13 shows an example in which a modulation rate of 60% is used, a pattern with a pressure ratio increased by approximately 30% relative to the load torque, and a phase difference of 12 degrees. FIG. 14 shows an example in which a modulation rate of 50% is used, a pattern with a pressure ratio increased by approximately 30% relative to the load torque, and a phase difference of 12 degrees. FIG. 15 shows an example in which a modulation rate of 40% is used, a pattern with a pressure ratio increased by approximately 30% relative to the load torque, and a phase difference of 12 degrees. FIG. 16 shows an example in which a modulation rate of 85% is used, a pattern with a pressure ratio reduced by approximately 20% relative to the load torque, and a phase difference of 6 degrees.

[0038] As shown in FIG. 9, if the pressure ratio of the output torque is appropriately set relative to the pressure ratio of the load (for example, if it is set to a value obtained by multiplying the pressure ratio of the load by the reciprocal of the modulation factor (≈1 / modulation factor-1)), the torque deviation can be reduced, and vibration suppression can be expected.

[0039] Furthermore, as shown in FIG. 10, if the pressure ratio of the output torque is made too large compared to the pressure ratio of the load, the torque deviation (deviation between the output torque and the load torque) becomes large.

[0040] Furthermore, as shown in FIG. 11, if the pressure ratio of the load and the pressure ratio of the output torque are set to be the same, the torque deviation (deviation between the output torque and the load torque) becomes large.

[0041] 12 to 15, if the output torque pattern is set so that the modulation rate of the output torque is a maximum of 75% and the torque deviation is minimized, lowering the modulation rate will increase the torque deviation and vibration (although losses can be reduced). However, since the effect of inertia comes into play, it is also possible to set a control specification that lowers the modulation rate as the rotation speed increases. In this case, by reducing the fluctuation range of the torque command value, it is possible to reduce losses, etc. that accompany changes in motor current, for example, and therefore improve efficiency.

[0042] Furthermore, as shown in Figure 16, increasing the modulation factor can suppress the increase in torque deviation without increasing the pressure ratio of the output torque. However, in the dashed-line area RA, the motor torque command (and the motor current value) becomes zero or a negative value. In this embodiment, position estimation is performed using the motor current, which may result in a deterioration in estimation accuracy. Therefore, in this embodiment, for example, by setting the modulation factor low (e.g., 75% or less), the deterioration in position estimation accuracy is avoided, and the pressure ratio of the output torque is appropriately set so as not to increase the torque deviation.

[0043] Next, the relationship between torque deviation and speed fluctuation will be explained with reference to Figures 17 and 18. For ease of understanding, let us consider the case where the load torque and output torque are sinusoidal. The relationship between torque deviation and speed fluctuation is as shown in Figures 17 and 18, and can be considered as follows. In actuality, when the torque waveform deviates from a sinusoidal waveform, multiple minimum or maximum values ​​appear in one rotation cycle, and a similar approach can be taken by comparing with the larger of these. Figures 17 and 18 show examples of changes in load torque, output torque, torque deviation (deviation between output torque and load torque), and speed fluctuation, with the horizontal axis representing the angle.

[0044] Figure 17 shows the torque deviation between the load torque and output torque (when delayed) and the acceleration / deceleration state. In the state shown in Figure 17, when the speed is at its maximum value and the torque command is small, the phase of the output torque is delayed, so the pattern is changed to one with a lower pressure ratio to advance the phase. Also, when the speed is at its minimum value and the torque command is large, the phase of the output torque is delayed, so the pattern is changed to one with a lower pressure ratio to advance the phase.

[0045] Figure 18 shows the torque deviation between the load torque and the output torque (when leading) and the acceleration / deceleration state. In the state shown in Figure 18, when the speed is at its maximum value and the torque command is large, the phase of the output torque is in a leading state, so the pattern is changed to one with a higher pressure ratio to delay the phase. Also, when the speed is at its minimum value and the torque command is small, the phase of the output torque is in a leading state, so the pattern is changed to one with a higher pressure ratio to delay the phase.

[0046] (Actions, Effects, etc.) According to this embodiment, compressor vibration can be suppressed over a wide range of load pressure conditions, making it possible to stabilize control (avoid motor step-out). Furthermore, since there is a trade-off between vibration suppression control and efficiency, when priority is given to vibration suppression, the modulation rate is set high, and when priority is given to efficiency, the modulation rate is lowered (while controlling the estimated rotation speed fluctuation to be within a predetermined threshold), allowing a certain degree of vibration, thereby reducing the effective value of the motor current and improving efficiency.

[0047] As described above, in this embodiment, multiple torque patterns are provided for active torque control. Furthermore, as shown in FIG. 3A , by including control phase information in the torque pattern, phase adjustment is essentially unnecessary when switching patterns. Furthermore, the torque modulation rate can be set somewhat low (approximately 75%), and the pressure ratio of the torque pattern can be set correspondingly higher (approximately 30% increase relative to the load). Note that torque pattern switching may also be determined based on, for example, estimated rotational speed fluctuation characteristics, heat exchanger temperature sensor values, pressure sensor values, or a combination thereof. Furthermore, the switching timing may be determined based on a position where the compression load is zero, a position where the estimated speed is low, or the like.

[0048] According to the control device, control method, and air conditioner of this embodiment, the control device 1 controls the inverter 4, which drives the motor 2 with AC current, to rotate the compressor 5, thereby controlling the rotation speed of the motor 2. The control device 1 also corrects the torque command value (average torque command value τa*) calculated based on the deviation Δω between the rotation speed of the motor 2 and the rotation speed command value based on one of multiple patterns TP1 to TP13 designed to accommodate load fluctuations on the compressor 5, and controls the inverter 4 based on the corrected torque command value (output torque command value τ*). In this process, the control device 1 recognizes one extreme value (P11) of a first polarity and two extreme values ​​(P21 and P22) of a second polarity different from the first polarity included in the waveform W1 of the deviation Δω during one rotation of the compressor 5, and selects one of multiple patterns based on information (P21, P22, Δτs) used to control the motor 2 obtained at each timing when the multiple extreme values ​​occur. This configuration allows the pattern to be appropriately selected in response to fluctuations in the load torque.

[0049] Second Embodiment Fig. 19 shows an example configuration of a pattern switching determination unit 265a according to a second embodiment of the present disclosure. The pattern switching determination unit 265a shown in Fig. 19 has a configuration corresponding to the pattern switching determination unit 265 shown in Fig. 5, and the second embodiment differs from the first embodiment only in the configuration of the pattern switching determination unit 265a. Compared to the pattern switching determination unit 265 shown in Fig. 5, the pattern switching determination unit 265a shown in Fig. 19 newly includes a pressure ratio change determination unit 268.

[0050] The pressure ratio change determination unit 268 estimates the pressure ratio of the compressor 5 based on the detection results of a heat exchanger temperature sensor (not shown) that measures the temperature of each part of the heat exchanger provided in the air conditioner 100, and partially restricts the function of the pattern switching command based on the estimated pressure ratio. The pressure ratio change determination unit 268 first converts the heat exchanger temperature to a pressure ratio (step S1). Next, the pressure ratio change determination unit 268 stores the pressure ratio (current) (step S2). Next, the pressure ratio change determination unit 268 does not output a pattern switching command if |current - previous| < a predetermined pressure ratio threshold. If current > previous, the pressure ratio change determination unit 268 only permits the output of a pattern switching command that increases the pressure ratio. If current < previous, the pressure ratio change determination unit 268 only permits the output of a pattern switching command that decreases the pressure ratio (step S3).

[0051] According to this embodiment, the torque pattern switching can be limited to when the pressure ratio changes by a predetermined pressure ratio threshold or more.

[0052] Other Embodiments Although the embodiments of the present disclosure have been described above in detail with reference to the drawings, the specific configuration is not limited to this embodiment and includes design modifications within the scope of the present disclosure. In the above embodiment, the rotational position, rotational speed, etc. are estimated based on current values, etc., without detecting them using sensors. However, the rotational position, rotational speed, etc. may be detected using sensors. Furthermore, the current value is not limited to detecting AC current using a sensor. For example, AC current may be estimated by detecting DC current input to an inverter circuit. In the above embodiment, the normalized torque pattern selector 26 includes the torque command difference calculator 261 and the speed fluctuation extreme value comparator 262. However, either one of these components may be omitted. In this case, either the first pattern switching determiner 263 or the second pattern switching determiner 264 may also be omitted. Furthermore, the pattern switching determiner 265 may not include the determiner 266, for example, and may output a pattern switching command based on either the first switching command or the second switching command.

[0053] <Computer Configuration> Fig. 20 shows an example configuration of a computer according to at least one embodiment. The computer 90 includes a processor 91, a main memory 92, a storage 93, and an interface 94. The above-described control devices 1, 1a, and 1b are implemented in the computer 90. The operations of the above-described processing units are stored in the storage 93 in the form of a program. The processor 91 reads the program from the storage 93, loads it into the main memory 92, and executes the above-described processing in accordance with the program. The processor 91 also allocates storage areas in the main memory 92 corresponding to the above-described storage units in accordance with the program.

[0054] The program may be for realizing some of the functions to be performed by the computer 90. For example, the program may be combined with other programs already stored in storage or implemented in other devices to perform the functions. In other embodiments, the computer may include a custom LSI (Large Scale Integrated Circuit) such as a PLD (Programmable Logic Device) in addition to or instead of the above configuration. Examples of PLDs include PAL (Programmable Array Logic), GAL (Generic Array Logic), CPLD (Complex Programmable Logic Device), and FPGA (Field Programmable Gate Array). In this case, some or all of the functions realized by the processor may be realized by the integrated circuit.

[0055] Examples of storage 93 include a hard disk drive (HDD), a solid state drive (SSD), a magnetic disk, a magneto-optical disk, a compact disc read-only memory (CD-ROM), a digital versatile disc read-only memory (DVD-ROM), and a semiconductor memory. Storage 93 may be an internal medium directly connected to the bus of computer 90, or an external medium connected to computer 90 via interface 94 or a communication line. Furthermore, if this program is distributed to computer 90 via a communication line, computer 90 that receives the program may load the program into main memory 92 and execute the above-described processing. In at least one embodiment, storage 93 is a non-transitory tangible storage medium.

[0056] <Additional Notes> The control device 1 described in each embodiment can be understood, for example, as follows.

[0057] (1) A control device 1 according to a first aspect of the present invention is a control device 1 that controls the rotation speed of a motor 2 by controlling an inverter 4 that AC-drives a motor 2 that rotates a compressor 5. The control device 1 corrects a torque command value (average torque command value τa) calculated according to a deviation Δω (speed fluctuation value Δω) between the rotation speed ωes of the motor 2 and a rotation speed command value ω* based on one of a plurality of patterns (TP1 to TP13) for responding to load fluctuations of the compressor 5. When controlling the inverter 4 based on the corrected torque command value (output torque command value τ*), the control device recognizes one extreme value (P11) of a first polarity and two extreme values ​​(P21, P22) of a second polarity different from the first polarity contained in a waveform W1 of the deviation (speed fluctuation value Δω) during one rotation of the compressor 5, and selects one of the plurality of patterns (TP1 to TP13) based on information (P11, P12, P22, Δτs) used in control of the motor 2 obtained at each timing when the plurality of extreme values ​​occurred.

[0058] (2) A control device 1 according to a second aspect is the control device 1 of (1), and selects one of the plurality of patterns using a comparison result of the magnitude of each of the deviations obtained at each timing when two extreme values ​​of the second polarity occur as the information. According to this aspect, it is possible to appropriately select a torque pattern depending on whether the output torque peak is delayed relative to the load torque peak.

[0059] (3) A control device 1 according to a third aspect is the control device 1 of (1) or (2), and selects one of the plurality of patterns using, as the information, a difference between the corrected torque command value obtained at the timing when an extreme value of the first polarity occurs and an average value of the torque command value, and a difference between the corrected torque command value obtained at the timing when one of the two extreme values ​​of the second polarity with a larger absolute value occurs and an average value of the torque command value. According to this aspect, it is possible to select a torque pattern based on information that is highly correlated with vibration suppression.

[0060] (4) A fourth aspect of the control device 1 is the control device 1 of any one of (1) to (3), wherein the plurality of patterns correspond to different pressure ratios of the compressor, and the selection of one of the plurality of patterns is performed in the order of magnitude of the pressure ratio in a direction that increases or decreases the pressure ratio, and the next pattern is selected when the direction of selection based on the comparison result matches the direction of selection based on the difference. According to this aspect, a sudden change in the torque pattern can be easily suppressed.

[0061] (5) A control device 1 according to a fifth aspect is the control device 1 of (1) to (4), in which the control device appropriately selects one of the plurality of patterns based on the information, corrects the torque command value based on the selected pattern, and controls the inverter based on the corrected torque command value, and switches between these operating states, depending on the rotation speed of the motor, to control the rotation speed of the motor. According to this aspect, compensation using the torque pattern can be easily minimized, and vibration can be reduced while efficiency is maintained.

[0062] (6) A control device 1 according to a sixth aspect is the control device 1 of any one of (1) to (5), and corrects the torque command value based on a value obtained by multiplying the pattern by a predetermined modulation factor. According to this aspect, the torque command value can be appropriately corrected.

[0063] DESCRIPTION OF SYMBOLS 1...Control device 2...Motor 3...AC power supply 4...Inverter 5...Compressor 10...Current sensor 11...Speed / position estimation unit 12...Speed ​​PI control unit 13...Load torque compensation unit 14...Subtraction unit 15...Addition unit 16...Current conversion unit 17...Subtraction unit 18...Current PI control unit 20...Speed ​​control unit 26...Normalized torque pattern selection unit 27...Addition unit 100...Air conditioner

Claims

1. A control device that controls the rotation speed of a motor by controlling an inverter that drives an AC motor to rotate a compressor, and corrects a torque command value calculated in accordance with the deviation between the rotation speed of the motor and a rotation speed command value based on one of a plurality of patterns for dealing with load fluctuations of the compressor, and when controlling the inverter based on the corrected torque command value, recognizes one extreme value of a first polarity and two extreme values ​​of a second polarity different from the first polarity contained in the waveform of the deviation during one rotation of the compressor, and selects one of the plurality of patterns based on information used in control of the motor obtained at each timing when the plurality of extreme values ​​occur.

2. The control device according to claim 1, wherein the control device selects one of the plurality of patterns using a comparison result of the magnitude of each of the deviations obtained at each timing when two extreme values ​​of the second polarity occur as the information.

3. The control device according to claim 2, wherein one of the plurality of patterns is selected using as the information a difference between the difference between the corrected torque command value obtained at the timing when an extreme value of the first polarity occurs and an average value of the torque command value, and a difference between the corrected torque command value obtained at the timing when an extreme value of the second polarity having a larger absolute value occurs and an average value of the torque command value.

4. The control device according to claim 3, wherein the plurality of patterns correspond to different pressure ratios of the compressor, and selection of one of the plurality of patterns is performed in the order of magnitude of the pressure ratio in a direction that increases or decreases the pressure ratio, and the next pattern is selected when the direction of selection based on the comparison result coincides with the direction of selection based on the difference.

5. A control device as described in claim 4, which controls the rotation speed of the motor by switching between an operating state in which one of the plurality of patterns is appropriately selected based on the information, the torque command value is corrected based on the selected pattern, and the inverter is controlled based on the corrected torque command value, and an operating state in which the torque command value is corrected based on one of the patterns, and the inverter is controlled based on the corrected torque command value, depending on the rotation speed of the motor.

6. The control device according to any one of claims 1 to 5, wherein the torque command value is corrected based on a value obtained by multiplying the pattern by a predetermined modulation factor.

7. A method for controlling the rotation speed of a motor by controlling an inverter that drives an AC motor to rotate a compressor, comprising the steps of: correcting a torque command value calculated according to a deviation between the rotation speed of the motor and a rotation speed command value based on one of a plurality of patterns for dealing with load fluctuations of the compressor; and, when controlling the inverter based on the corrected torque command value, recognizing one extreme value of a first polarity and two extreme values ​​of a second polarity different from the first polarity contained in the waveform of the deviation during one rotation of the compressor; and selecting one of the plurality of patterns based on information used in controlling the motor obtained at each timing when the plurality of extreme values ​​occurred.

8. An air conditioner comprising: a compressor; a motor which rotates and drives the compressor; an inverter which AC drives the motor; and a control device which controls the inverter to control the rotation speed of the motor, the control device correcting a torque command value calculated according to a deviation between the rotation speed of the motor and a rotation speed command value based on one of a plurality of patterns for dealing with load fluctuations of the compressor, and controlling the inverter based on the corrected torque command value, the control device recognizing one extreme value of a first polarity and two extreme values ​​of a second polarity different from the first polarity contained in a waveform of the deviation during one rotation of the compressor, and selecting one of the plurality of patterns based on information used in control of the motor obtained at each timing when the plurality of extreme values ​​occur.

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