SPEED ESTIMATOR FOR AC MOTOR, DRIVE DEVICE FOR AC MOTOR, REFRIGERATING COMPRESSOR AND REFRIGERATING CYCLE DEVICE

Abstract

A speed estimation device (101, 101C, 101D, 101E) for an AC motor (2), the speed estimation device (101, 101C, 101D, 101E) comprising: a model deviation calculation unit (11) for calculating a model deviation based on a voltage, a current and an estimated angular velocity of the AC motor (2); a first angular velocity estimation unit (21) for calculating a first estimated angular velocity based on the model deviation; a second angular velocity estimation unit (22) for calculating a second estimated angular velocity based on the model deviation, the second estimated angular velocity being different from the first estimated angular velocity in terms of frequency; a compensation phase calculation unit (51) for calculating a compensation phase based on a disturbance frequency; and an estimated angular velocity calculator (23) for calculating an estimated angular velocity of the AC motor (2) on the basis of the first and second estimated angular velocities, wherein an angular velocity estimated from the first and second is calculated on the basis of the compensation phase.

Description

Technical FieldThe present invention relates to a speed estimation device for an AC motor that estimates the speed of an AC motor such as an asynchronous machine or a synchronous machine, a drive device for an AC motor, a refrigerant compressor, and a refrigeration cycle device.General State of the ArtIn the control of an AC motor, when the load torque or torque generated by the AC motor has a variation, a certain amount of pulsation occurs even at the rotational speed of the AC motor. The occurrence of pulsation in the rotational speed of the AC motor may generate vibration in a device on which the AC motor is installed, which may be problematic in terms of the occurrence of noise, mechanical strength, or the like. In response to these problems, a control for reducing torque pulsation and rotational speed pulsation has been considered.For example, Patent Document 1 listed below teaches a technique for achieving feedback control for reducing torque pulsation and rotational speed pulsation by a sensorless technique without using a position sensor or a speed sensor to reduce cost or to enable application to a device on which a sensor is difficult to install. According to Patent Document 1, a torque compensation value is obtained based on a rotational ripple component extracted from a difference between an instruction angular frequency and a rotational feedback angular frequency. The variation of the rotational speed of the AC motor is thus reduced or suppressed, which makes do without any map for correction amounts entirely. Patent Document 2 relates to a rotation speed estimation device that estimates the rotation speed of an AC motor, such as an induction machine or a synchronous machine, a drive device for the AC motor, a refrigerant compressor, and a refrigeration cycle device.Patent Document 3 relates to a motor control device, particularly to a motor control device that variably controls the rotation speed of a permanent magnet synchronous motor by sensorless control.Patent Document 4 relates to the field of electric machines, and more particularly, to synchronous machines including a rotor and a stator. More specifically, Patent Document 4 relates to a correction system for correcting an estimate of a position of the rotor.List of InstructionsPatent LiteraturePatent Document 1: JP 6 222 417 B1Patent Document 2: DE 11 2017 002 279 B4Patent Document 3: US 2013 / 0 314 016 A1Patent Document 4: EP 2 706 659 A1SummaryTechnical TaskIn the case of position sensorless control, an upper limit of the response in the speed estimation in conventional control systems is several hundred [rad / s], and therefore a response to high-frequency pulsation is insufficient and pulsation can hardly be accurately estimated. Further, in Patent Document 1, since a vibration reducing unit is configured to use an estimated rotation speed, the performance of the vibration reducing unit depends on a response in the rotation speed estimation, and is thereby considered to be insufficient in a high frequency range.The present invention has been made in view of the above, and an object thereof is to provide a speed estimation device for an AC motor capable of further enhancing the accuracy of speed estimation at high frequency in sensorless control of an AC motor.Solution of the ProblemIn order to solve the above problems and achieve the object, the present invention provides a rotation speed estimation device for an AC motor, the rotation speed estimation device comprising: a model deviation calculation unit for calculating a model deviation based on a voltage, a current, and an estimated angular speed of the AC motor; a first angular speed estimation unit for calculating a first estimated angular speed based on the model deviation; a second angular speed estimation unit for calculating a second estimated angular speed based on the model deviation, the second estimated angular speed being different in frequency from the first estimated angular speed; a balance phase calculation unit for calculating a balance phase based on a disturbance frequency; and an estimated angular velocity calculator for calculating an estimated angular velocity of the AC motor based on the first and second estimated angular velocities, wherein one of the first and second estimated angular velocities is calculated based on the compensation phase.Advantageous Effects of the InventionThe speed estimation device for an AC motor according to the present invention produces an advantageous effect in that it is capable of further enhancing the accuracy of speed estimation at high frequency in sensorless control of an AC motor.Brief Description of the DrawingsFIG. 1 is a block diagram illustrating a configuration of a speed estimation device for an AC motor according to a first embodiment. FIG. 2 is a block diagram illustrating a configuration of a rotation speed estimation device according to a comparative example. FIG. 3 is a Bode diagram illustrating transmission characteristics of the speed estimation device illustrated in FIG. 2. FIG. 4 is a block diagram illustrating a configuration of a rotation speed estimation device according to a comparative example other than FIG. 2. FIG. 5 is a Bode diagram illustrating transmission characteristics of the speed estimation device illustrated in FIG. 4. FIG. 6 is a diagram used for comparing Bode diagrams illustrating transmission characteristics from a model deviation ε to a first estimated angular acceleration of the speed estimation device illustrated in FIG. 2 in an open-loop characteristic and a closed-loop characteristic. FIG. 7 is a block diagram illustrating a detailed configuration of a second angular velocity estimation unit in the rotational speed estimation device shown in FIG. 1. FIG. 8 is a block diagram illustrating a modification of the detailed configuration illustrated in FIG. 7. FIG. 9 is a first diagram provided for explaining the effect of the rotation speed estimation device according to the first embodiment. FIG. 10 is a second diagram provided for explaining the effect of the speed estimation device according to the first embodiment. FIG. 11 is a diagram of a hardware configuration of the rotation speed estimation device according to the first embodiment. FIG. 12 is a block diagram illustrating a configuration of a speed estimation device according to a second embodiment. FIG. 13 is a block diagram illustrating a configuration of a speed estimation device according to a third embodiment. FIG. 14 is a block diagram illustrating a configuration of a speed estimation device according to a fourth embodiment. FIG. 15 is a diagram illustrating an example of a waveform of a load torque of a rotary compressor. FIG. 16 is a block diagram illustrating a configuration of a drive device for an AC motor according to a fifth embodiment. FIG. 17 is a block diagram illustrating a configuration of a drive device for an AC motor according to a sixth embodiment. FIG. 18 is a cross-sectional view illustrating a schematic structure inside a refrigerant compressor illustrated as a driven object in FIG. 17. FIG. 19 is a cross-sectional view illustrating a structure inside a compression space of the refrigerant compressor illustrated in FIG. 18. FIG. 20 is a diagram illustrating a configuration of a refrigeration cycle device according to a seventh embodiment.DESCRIPTION OF EMBODIMENTSA speed estimation device for an AC motor, a driving device for an AC motor, a refrigerant compressor, and a refrigeration cycle device according to certain embodiments of the present invention will be described in detail below with reference to the drawings. It should be noted that the present invention is not limited by the embodiments described below. Hereinafter, the rotation speed estimating device for an AC motor will be referred to simply as a "rotation speed estimating device", as appropriate. Further, the driving device for an AC motor is simply referred to as a "driving device", as appropriate.First EmbodimentFIG. 1 is a block diagram illustrating a configuration of a speed estimation device 101 for an AC motor according to a first embodiment. The rotation speed estimation device 101 illustrated in FIG. 1 estimates the rotation speed of an AC motor 2 in an adaptive observer technique using a voltage vector applied to the AC motor 2 and a current vector, and outputs the estimation result as the estimated angular speed ω^ r.The rotation speed estimation device 101 includes a model deviation calculation unit 11, a first angular velocity estimation unit 21, a compensation phase calculation unit 51, a second angular velocity estimation unit 22, and an estimated angular velocity calculator 23.The model deviation calculation unit 11 calculates a model deviation ε on the basis of the voltage vector, the current vector, and the estimated angular velocity ω^ r. The first angular velocity estimation unit 21 calculates a first estimated angular velocity ω^ r1 on the basis of the model deviation ε. The compensation phase calculation unit 51 calculates a compensation phase θ pls on the basis of a specific interference frequency f d. The second angular velocity estimation unit 22 calculates a second estimated angular velocity ω^ r2 on the basis of the compensation phase θ pls, the model deviation ε, and the disturbance frequency f d. The estimated angular velocity calculator 23 calculates an estimated angular velocity ω^ r of the AC motor 2 based on the first estimated angular velocity ω^ r1 and the second estimated angular velocity ω^ r2.The speed estimation device 101 includes the compensation phase calculation unit 51 and the second angular velocity estimation unit 22, and operations performed by these components constitute one of the features of the present invention. Details of the compensation phase calculation unit 51 and the second angular velocity estimation unit 22 will be described later.In the first embodiment, the disturbance frequency f d is assumed to be known. The interference frequency f d can be obtained in any desired manner. For example, in such a system in which interference of each frequency occurs, the interference frequency f d may be provided as a constant in advance. Alternatively, in an application such as a compressor in which a disturbance occurs depending on the rotation frequency, the rotation frequency may be used as the disturbance frequency f d. The rotational frequency referred to herein may be obtained by a rotational position measurement sensor or a speed sensor. Alternatively, in the case of an apparatus including means for estimating the angular velocity, as in the first embodiment, the rotational frequency may be obtained from the estimated angular velocity ω^ r. As a further alternative, the frequency of the torque pulsation can be detected or estimated with the aid of a torque meter, an acceleration sensor or a vibration sensor and used as the interference frequency f d.The first angular velocity estimation unit 21 and the second angular velocity estimation unit 22 both estimate the angular velocity. The difference therebetween is a frequency for an angular velocity to be estimated. Although the first embodiment is directed to a configuration in which the first angular velocity estimation unit 21 estimates a low-frequency component including a direct current (DC) component of an angular velocity and the second angular velocity estimation unit 22 estimates a high-frequency component of the angular velocity, the present invention is not limited to this configuration. It is understood that an opposite configuration may alternatively be used in which the first angular velocity estimation unit 21 estimates an angular velocity component having a higher frequency.Next, a configuration and functions of the model deviation calculation unit 11 will be described. The model deviation calculation unit 11 includes a state estimator 12, a subtractor 13, and a deviation calculator 14. the state estimator 12 calculates and outputs a vector related to the estimated magnetic flux and a vector related to the estimated current on the basis of the voltage vector applied to the AC motor 2, the current vector output by the AC motor 2, and the estimated angular velocity ω^ r. The estimated angular velocity ω^ r is an estimated angular velocity calculated by the aforementioned estimated angular velocity calculator 23, and also an output of the rotational speed estimator 101.The subtracter 13 subtracts the current vector from the estimated current vector to calculate a current deviation vector. The deviation calculator 14 receives the current deviation vector as its input, extracts an orthogonal component of the estimated magnetic flux related vector as a scalar quantity, and outputs a value of the quantity as a model deviation ε. Note that the technique of extracting an orthogonal component of a vector related to the estimated magnetic flux is known as a scalar quantity. For example, a technique of performing coordinate transformation on a current deviation vector on two rotation axes, a technique of calculating the size of the cross product of the current deviation vector and the estimated magnetic flux related vector, and others are known in the art.Specifically, the state estimator 12 estimates an electric current and a magnetic flux according to a state equation of the AC motor 2, although the AC motor 2 is assumed to be a typical synchronous AC electric motor of the type in which magnets are installed in this example, any other AC motors may be used as long as a state equation similar to that described below can be established in the state estimator 12. Examples of other AC motors include a synchronous electric motor of the type having surface magnets and an asynchronous electric motor.In the case of a synchronous AC motor of the type in which magnets are installed, the equation of state is expressed by the following equations (1) and (2). [Formula 1] [Formula 2]In Equations (1) and (2), L d and L q represent inductances on a d-axis and a q-axis, respectively. R stands for an armature resistance. ω stands for a primary angular frequency. ω r stands for an angular velocity. v ds stands for a d-axis voltage. vqs stands for a q-axis voltage. i ds stands for a d-axis current. iqs stands for a q-axis current. φ ds stands for a d-axis stator magnetic flux. φqs stands for a q-axis stator magnetic flux. φ ar stands for a d-axis rotor magnetic flux. h 11 to h 32 stand for observer gains. The symbol "^" represents an estimated value.Note that the primary angular frequency is given as expressed according to the following equation (3). [Formula 3]In the above equation (3), h 41 and h 42 represent observer gains similar to the aforementioned h 11 to h 32.Although the above equations (1) and (2) are equations based on the normal induced voltage, similar calculation may be made by modifying the above equations (1) and (2) to express a shape using an extended induced voltage. Since the above equation (1) includes the estimated angular velocity ω^ r an error occurs in current estimation when the estimated angular velocity ω^ r and an actual angular velocity ω r do not match each other. The model deviation ε is defined according to the following equation (4). The rotation speed estimation device 101 adjusts the value of the estimated angular velocity ω^ r using the first angular velocity estimation unit 21 and the second angular velocity estimation unit 22 so that the model deviation ε becomes zero. [Formula 4]As described above, one of the characteristics of the rotation speed estimation device 101 is that the rotation speed estimation device 101 includes the compensation phase calculation unit 51 and the second angular speed estimation unit 22. Here, in order to explain this feature, a rotation speed estimation device which does not include the compensation phase calculation unit 51 and the second angular velocity estimation unit 22 will be first explained as a comparative example.FIG. 2 is a block diagram illustrating a configuration of a rotation speed estimation device 101A according to the comparative example. The speed estimating device 101A shown in FIG. 2 functions according to a sensorless vector control method in a manner similar to the speed estimating device 101 shown in FIG. 1. The rotation speed estimation device 101A functions to adjust the model deviation ε to zero, which is performed by using only the first angular velocity estimation unit 21.In the case of the speed estimation device 101A illustrated in FIG. 2, the first angular velocity estimation unit 21 includes a proportional and integral behavior (PI) controller 24 and an integrator 25. [Formula 5]In the equation (5), K P represents a proportional gain of the entire first angular velocity estimation unit 21. K I represents an integral gain of the entire first angular velocity estimation unit 21. s represents an operator of a Laplace transform, where s refers to differentiation and 1 / s refers to integration.In the first angular velocity estimation unit 21, the PI controller 24 calculates a first estimated angular acceleration ω·^ r1 on the basis of the model deviation ε. The integrator 25 integrates the first estimated angular acceleration ω·^ rı, to calculate the first estimated angular velocity ω^ r1. In the first angular velocity estimation unit 21, the first estimated angular velocity ω^ r1 is adjusted by the PI controller 24 and the integrator 25. The first estimated angular velocity ω^ r1 is output to the outside as the output of the speed estimator 101A. Further, the first estimated angular velocity ω^ r1 is fed back to the model deviation calculation unit 11. As described above, the PI controller 24 functions as the first angular acceleration estimator and the integrator 25 functions as the first angular velocity calculator.Further, the transfer function Ga(s) from the first estimated angular velocity ω^ r1 to the model deviation ε is previously known from the 226-side speed sensorless vector control method of induction motor including A low speed region, The transactions of the Institute of Electrical Engineers of Japan (Vol. 120-D, No. 2, 2000), which is non-patent literature. The transfer function Ga(s) can be approximated by a first-order delay as in the following equation (6). [Formula 6]FIG. 3 is a Bode diagram illustrating transmission characteristics of the rotation speed estimation device 101A illustrated in FIG. 2. The horizontal axis represents the frequency, the vertical axis the gain. A transfer function (1) shown by a broken line in FIG. 3 is designed such that the gain is higher in a lower frequency range. In the tansfer function of (1), the gain decreases as the frequency is higher. Specifically, the gain decreases at a rate of -40 [dB / decade] in a low frequency band; at frequencies higher than those at the changeover point P1, it decreases at a rate of -20 [dB / decade].In addition, a tansfer function of (2), which is shown as a dotted line in FIG. 3, corresponds to the tansfer function Ga(s) of the above equation (6). Since the tansfer function Ga(s) has a property of first-order delay from the first estimated angular velocity ω^ r1 to the model deviation ε, the gain decreases at a rate of -20 [dB / decade] in a frequency range that is above a cutoff angular frequency f1. The addition of the two transfer functions yields a transfer function of (3) having an open circle characteristic, shown as a solid line.In the PI controller, when there is a gain in the above equation (5), that is, the proportional gain K P and the integral gain K I can be set to be sufficiently large in the first angular velocity estimation unit 21, the rotation speed pulsation at high frequencies can be accurately estimated. However, these gain values are limited by the time for the calculation of the estimation and the influence of an error in a motor constant. A forced increase in gains increases susceptibility to high frequency noise, making proper estimation processing impossible. Consequently, the rotation speed estimation device 101A according to the comparative example is accompanied with a problem in that it is difficult to detect a high-frequency rotation speed pulsation.Next, another comparative example will be explained. FIG. 4 is a block diagram illustrating a configuration of a rotation speed estimation device 101B according to a comparative example other than FIG. 2. To distinguish FIG. 2, the comparative example of FIG. 2 will be referred to as "first comparative example" and the comparative example of FIG. 4 will be referred to as "second comparative example" below. In comparison with the rotation speed estimation device 101A in FIG. 2, the rotation speed estimation device 101B according to the second comparative example illustrated in FIG. 4 is additionally provided with a second angular velocity estimation unit 22B.In the case of the rotational speed estimation device 101B in FIG. 4, the second angular velocity estimation unit 22B includes a second angular acceleration estimation unit 30B and an integrator 31. the second angular acceleration estimation unit 30B calculates a second estimated angular acceleration ω·^ r2 on the basis of the disturbance frequency f d and the model deviation ε. The integrator 31 integrates the second estimated angular acceleration ω·^ r2 and outputs a second estimated angular velocity ω·^ r2.Further, the second angular acceleration estimating unit 30B includes a Fourier coefficient calculator 26, RI controllers 27 and 28, and an AC motor restoring unit 29.The Fourier coefficient calculator 26 converts a specific frequency component of the model deviation into DC power and extracts the obtained DC power component. A cosine coefficient E c and a sine coefficient E s are output from the Fourier coefficient calculator 26 and correspond to the specific frequency component obtained by the DC conversion.In this process, the cosine coefficient E c of the model deviation ε and the sine coefficient E s of the model deviation ε are calculated from the following equations (7) and (8), respectively, based on the model deviation ε and the disturbance frequency f d. [Formula 7] [Formula 8]In the formulas (7) and (8), t represents time. In addition, T d represents a period of oscillation of the disturbance, which is the reciprocal of the disturbance frequency f d. That is, T d=1 / f d.The cosine coefficient E c of the model deviation is subjected to the PI control by the PI controller 27 as expressed by the following equation (9): Further, the sine coefficient E s is subjected to the model deviation of the PI control by the PI controller 28 as expressed by the following equation (10): [Formula 9] [Formula 10]In Equations (9) and (10), K P2 represents a proportional gain of the entire second angular velocity estimation unit 22B. K I2 represents an integral gain of the entire second angular velocity estimation unit 22B. A point above each character denotes differentiation; the number of points represents the differentiation order.The AC recovery unit 29 performs calculation of the following equation (11) on the basis of the cosine coefficient E c of the model deviation and the sine coefficient E s of the model deviation. Equation (11) is an arithmetic expression for calculating the second estimated angular acceleration ω·^ r2. [Formula 11]FIG. 5 is a Bode diagram illustrating transmission characteristics of the rotation speed estimation device 101B illustrated in FIG. 4. The horizontal axis represents the frequency, the vertical axis the gain. A transfer function of (1) in FIG. 5 agrees with the transfer function of (1) in FIG. 3. A transfer function of (2) in FIG. 5 agrees with the transfer function of (2) in FIG. 3. A transfer function of (3) in FIG. 5 illustrates a transfer function of the second angular velocity estimation unit 22B illustrated in FIG. 4. The addition of the three transfer functions yields an open circle characteristic of (4) shown as a solid line.In FIG. 5, as compared with FIG. 3, the gain in a specific frequency band is stronger in the open-circle characteristic of (4) shown by the solid line. More specifically, the rotation speed estimation device 101B according to the second comparative example increases the gain in a specific frequency band in which occurrence of rotation speed pulsation due to periodic disturbance can be predicted, which is performed using the first angular velocity estimation unit 21 and the second angular velocity estimation unit 22B, thereby enabling an increase in the accuracy of the rotation speed estimation. As a result, the rotation speed estimation device 101B according to the second comparative example enables estimation of the high-frequency rotation speed pulsation with high accuracy, which is difficult for the rotation speed estimation device 101A according to the first comparative example.As described above, the speed estimation device 101B according to the second comparative example can estimate the high-frequency speed pulsation with high accuracy; however, it is considered that the control system may be unstable depending on the amount of phase error. In view of these circumstances, the present inventors have considered the need for phase compensation for a proposal of the present invention, and such consideration will be described below.FIG. 6 is a diagram used for comparing Bode diagrams representing the transmission characteristics from the model deviation ε to the first estimated angular acceleration ω·^ r1 of the rotation speed estimation device 101A illustrated in FIG. 2 in an open-circle characteristic and a closed-circle characteristic. The open circle property is a transfer property in a state where the first estimated angular velocity ω^ r1 is not fed back to the model deviation calculation unit 11. The closed-loop characteristic is a transfer characteristic in a state in which the first estimated angular velocity ω^ r1 is fed back to the model deviation calculation unit 11 as illustrated in FIG. 2. Note that FIGS. 3 and 5 are Bode plots from the model deviation ε to the first estimated angular velocity ω^ r1. In contrast, FIG. 6 illustrates the transfer characteristics from the input of the model deviation ε to the output of the first estimated angular acceleration ω·^ r1 and it should be noted that FIGS. 3 and 5 have been supplemented with a characteristic of a first-order differential. As illustrated in FIG. 4, when the second angular velocity estimation unit 22B calculates the second estimated angular acceleration ω·^ r2 on the basis of the model deviation ε, the characteristic from the input of the model deviation ε to the output of the second estimated angular acceleration ω·^ r2, illustrated in FIG. 6, may be regarded as a characteristic to be controlled by the second angular velocity estimation unit 22B.In feedback control, a design technique is often used in consideration of open loop characteristics of a controlled object and control. In this situation, first, a case of configuring the second angular velocity estimation unit in view of the open-circle property of the controlled object is considered.According to the open loop characteristics in FIG. 6, the gain decays at -20 [dB / decade] in a low frequency band. The phase is -90 [deg] in the low frequency band, is delayed at higher frequency, and converges to -180 [deg]. While the frequency band used depends on the application, it can be considered that the phase at -90 [deg] is substantially constant in a case where a low frequency band is mainly used. In such a case, when the open-loop property is a controlled object in designing the second angular velocity estimation unit, phase compensation seems to be unnecessary.However, the PI controllers 27 and 28 serving as the second angular acceleration estimator perform calculation in a state where the PI controller 24 serving as the first angular acceleration estimator operates. For this reason, it should be considered that the first estimated angular velocity ω^ r1, which is estimated by the first angular velocity estimation unit 21 including the PI controller 24, is fed back to the model deviation calculation unit 11.Accordingly, the second angular velocity estimation unit 22B needs to be designed in consideration of the closed-loop property to be controlled by the angular velocity estimation unit 22B.The closed loop characteristic in FIG. 6 includes a characteristic of a first order integral in a high frequency band and a characteristic of a first order differential in a low frequency band. The gain has a characteristic that decreases with a gradient of -20 [dB / decade] in accordance with the characteristic of an open loop in a high frequency band, but has a characteristic that increases with a gradient of +20 [dB / decade] in a low frequency band and causes the gain to decrease at a lower frequency. Further, the phase converges to -180 [deg] in a high frequency band, which is consistent with the case of the open loop; however, in a low frequency band, it is +90 [deg]. Thus, the phase significantly changes from +90 [deg] to -180 [deg] in the frequency band therebetween.Note that, as described above, the calculation of the angular acceleration in the second angular velocity estimation unit 22B of the rotation speed estimation device 101B according to the second comparative example is performed using the above equations (7) to (11). Equations (7) and (8) are arithmetic expressions for obtaining the cosine coefficient and the sine coefficient corresponding to DC components, equations (9) and (10) are arithmetic expressions for PI control, and equation (11) is an arithmetic expression for restoring an AC component by re-including the DC components in the AC component. In the series of calculation processes, the phase is not taken into account. That is, it is assumed that the phase does not change with frequency in a range from the input of the model deviation ε to the output of the second estimated angular acceleration ω·^ 2.For example, as described above, in the case where only the open loop property is considered to be a controlled object and the operation is performed in a low frequency range, the phase change may be considered to be small enough, and it is considered to apply the control configuration as described above. However, the phase characteristic of a controlled object changes significantly with frequency as shown in the Bode diagrams in FIG. 6. For this reason, an error is caused with respect to an estimated phase of each angular acceleration unless an estimated angular acceleration is calculated in view of the fact that the phase characteristic of a controlled object changes with the disturbance frequency.The second angular acceleration estimating unit 30B in the second comparative example calculates an angular acceleration using the PI controllers 27 and 28. When a phase error is small enough, the phase in this configuration may converge to an appropriate value due to adjustment of a controlled variable by the PI controllers 27 and 28. However, in a frequency band in which a phase error is significantly large, the feedback control may become unstable.In view of these circumstances, the second angular velocity estimation unit 22 in the first embodiment includes a control system for performing phase compensation so that an angular velocity can be calculated at an appropriate phase. FIG. 7 is a block diagram illustrating a detailed configuration of the second angular velocity estimation unit 22 in the rotation speed estimation device 101 shown in FIG. 1. As illustrated in FIG. 7, the second angular acceleration estimation unit 30 includes a Fourier coefficient calculator 52, integral (I) controllers 53 and 54, and an AC motor recovery unit 55. Further, in the second angular acceleration estimating unit 30, the Fourier coefficient calculator 52 functions as a specific frequency extractor that extracts a specific frequency component, and the I controllers 53 and 54 and the AC motor restoring unit 55 function as a specific frequency angular acceleration estimator.In FIG. 7, the disturbance frequency f d is input to the compensation phase calculation unit 51, the Fourier coefficient calculator 52, and the AC motor recovery unit 55. The compensation phase calculation unit 51 determines a compensation phase θ pls in view of the closed loop property to be controlled. Specifically, the compensation phase θ pls is stored as a graph associated with the interference frequency, and the compensation phase θ pls can be determined by referring to the graph. Alternatively, an approximation formula changed depending on the disturbance frequency may be applied, and the compensation phase θ pls may be determined using the approximation formula. The compensation phase θ pls is input to the Fourier coefficient calculator 52.The Fourier coefficient calculator 52 obtains the cosine coefficient E c' and the sine coefficient E s' of the model deviation based on the disturbance frequency f d and the compensation phase θ pls using the following equations (12) and (13). [Formula 12] [Formula 13]The cosine coefficient E c' of the model deviation is subjected to the I control by the I controller 53 as expressed by the following equation (14): Further, the sine coefficient E s' is subjected to the model deviation of the I control by the I controller 54 as expressed by the following equation (15): [Formula 14] [Formula 15]In the above equations (14) and (15), K rpl_i represents the integral gain of the I regulators 53 and 54, and it should be noted that the cosine coefficient E c' and the sine coefficient E s', which are control inputs to the I regulators 53 and 54, are in a magnitude of angular velocity, whereas control outputs of the I regulators 53 and 54 are in a magnitude of angular acceleration. In addition, the conversion of an angular velocity to an angular acceleration has a differentiation ratio, whereas a controlled object naturally has an integrating property. Therefore, the cosine coefficient E c' and the sine coefficient E s', which are control inputs, each appear as a gain of a multiple of the conversion frequency in a coordinate system resulting from the conversion to direct current. The cosine coefficient E c' and the sine coefficient E s' are therefore considered to be a proportional property in this coordinate system and not an integrating property. In this situation, the control can be made only by integrators, and therefore the I controllers 53 and 54 are used. It is understood that PI controllers may be used as needed to improve responsiveness as in the second comparative example.The AC restoration unit 55 performs the calculation of the following equation (16) on the basis of the cosine coefficient E c' and the sine coefficient E s'. This equation (16) is an arithmetic expression for calculating the second estimated angular acceleration ω·^ r2. [Formula 16]FIG. 9 is a first diagram used for explaining the effect of the rotation speed estimation device 101 according to the first embodiment. FIG. 10 is a second diagram used for explaining the effect of the rotation speed estimation device 101 according to the first embodiment. Both FIGS. 9 and 10 illustrate an example of a result of a simulation in which the AC motor 2 is driven by being provided with rotation speed pulsation and the rotation speed of the AC motor 2 is estimated. In this simulation, the second angular velocity estimation unit 22 is activated and estimation of the rotational speed pulsation is started five seconds after driving the AC motor 2.Further, FIG. 9 illustrates waveforms obtained by plotting cosine components Ω c ·^ of angular acceleration estimated with estimation response set to 1 [rad / s], and sine components O s ·^ of angular acceleration. The upper part thereof represents waveforms in a case without phase compensation, which corresponds to a result obtained by the configuration in the second comparative example. The lower part thereof represents waveforms in a case of phase compensation corresponding to a result obtained by the configuration of the first embodiment.Because of some susceptibility to errors in an estimated phase of the rotational speed pulsation as described above, the value for the angular acceleration does not converge but diverges in the case without phase compensation, and a fixed response cannot be obtained. In contrast, in the case of phase compensation, it can be recognized that the estimated angular acceleration converges and the operation is stable. It can also be seen that the response speed increases by 63% in approximately one second from the start of the estimation and the desired response is thus achieved.Further, FIG. 10 illustrates curves of an estimated angular velocity, the upper part of which represents a case with no phase compensation and the lower part of which represents a case with phase compensation. A left part of each of the upper and lower parts represents waveforms before activation of the second angular velocity estimation unit 22, and a right part of each of the upper and lower parts represents waveforms after the second angular velocity estimation unit 22 is activated and the value is converged. Each bold curve represents an actual angular velocity and each sparse curve represents an estimated angular velocity.Before activation, the phase of the estimated angular velocity lags behind the actual angular velocity; moreover, the amplitude of the estimated angular velocity is less than that of the actual angular velocity. After activation, in the case without phase compensation, the control diverges and the amplitude of the estimated angular velocity is significantly greater than that of the actual angular velocity, and the phase thereof also has a difference from the latter. In contrast, in the case of phase compensation, the estimated angular velocity corresponds to the actual angular velocity, and it can be seen that the control is performed satisfactorily.The integrator 31 integrates the second estimated angular acceleration ω·^ r2, which is calculated by the AC recovery unit 55 from the following equation (17), to obtain the second estimated angular velocity ω^ r2. The integrator 31 functions as a second angular velocity calculator. The second estimated angular velocity ω^ r2 is calculated as a specific high frequency component of the actual angular velocity. [Formula 17]It should be noted that it will be apparent to those skilled in the art that a block diagram of a control system may be modified. For example, a configuration as in FIG. 8 may be implemented. FIG. 8 is a block diagram illustrating a modification of the configuration of a single part illustrated in FIG. 7. For example, the configuration of integrators 25 and 31 in FIG. 7 may be modified to be such a configuration that the estimated angular accelerations are added before passing through an integrator. Specifically, while two integrators 25 and 31 are located on input sides of the estimated angular velocity calculator 23 in the configuration in FIG. 7, one integrator 32 may be located on an output side of the estimated angular velocity calculator 23, as in the rotation speed estimation device 101- 1 in FIG. 8, this configuration brings about an advantageous effect that it is possible to reduce the number of integrators.An equation for estimating a final angular velocity is expressed by the following equation (18). Specifically, in the estimated angular velocity calculator 23, the second estimated angular velocity ω^ r2, which has been calculated by the integrator 31, is added to the first estimated angular velocity ω^ r1 calculated by the first angular velocity estimator 21, thereby obtaining the estimated angular velocity ω^ r which is expressed by the following equation (18). [Formula 18]Although an example of using an adder is described in the above equation (18) and with respect to the estimated angular velocity calculator 23 shown in FIG. 7, the present invention is not limited to this example. In such a case that the definition of a positive value or negative value of the compensation phase in the compensation phase calculation unit 51 and the definition of an output of the AC recovery unit 55 have an opposite phase, a subtractor is used. In other words, the configuration of the estimated angular velocity calculator 23 is determined depending on the definition of a positive value or negative value of the compensation phase, the definition of an output of the AC recovery unit 55, and the like.A difference between the equation (18) and the equation (5) is that the second estimated angular velocity ω^ r2 is used in the equation (18). The second angular velocity estimation unit 22 converts each harmonic wave of the model deviation ε into DC currents by dividing the harmonic wave into a sine wave and a cosine wave, extracts the sine wave and the cosine wave, and I-controls so that the sine wave and the cosine wave become zero. The second angular velocity estimation unit 22 then restores the output of the I control to an alternating current to estimate a high-frequency component of the actual angular velocity, and increases the gain only partially at a certain frequency. Therefore, a rotational speed pulsation component due to periodic disturbance can be estimated with high accuracy as the second estimated angular speed ω^ r2. Note that the above-described second angular velocity estimation unit 22 has a structure of the type of an iterative controller or a learning controller. Accordingly, instead of the second angular velocity estimation unit 22, another type of iterative controller or learning controller may be used.FIG. 11 is a diagram of a hardware configuration of the rotation speed estimation device 101 according to the first embodiment. Although not illustrated in FIGS. 1 and 7, a voltage application unit 3 and a current detection unit 4 are illustrated in FIG. 11. The voltage application unit 3 serves as voltage application means for applying a voltage to the AC motor 2. The voltage vector corresponds to a voltage command generated by the voltage applying unit 3. A voltage generated based on the voltage command is applied to the AC motor 2, and information on the voltage command enters the rotation speed estimation device 101. Further, the current vector is generated by the current detection unit 4 and enters the rotation speed estimation device 101. The current vector is vector information regarding an alternating current flowing in the alternating current motor 2. An example of the current vector is a detected value of dq-axis current obtained by converting an alternating current detected by the current detection unit 4 to a value on a dq coordinate axis.The speed estimation device 101 includes a processor 901 and a memory 902. The memory 902 includes a volatile memory device not illustrated exemplified by a random access memory, and a nonvolatile auxiliary memory device not illustrated exemplified by a flash memory. Note that the memory 902 may include an auxiliary storage device of a hard disk in place of the volatile storage device and the auxiliary nonvolatile storage device. The processor 901 executes a program input from the memory 902. Since the memory 902 includes an auxiliary storage device and the volatile storage device, a program is input from the auxiliary storage device to the processor 901 via the volatile storage device. The processor 901 may input data on a calculation result to the volatile storage device of the memory 902 and store the data in the auxiliary storage device via the volatile storage device.Various systems have been considered for the voltage application unit 3 and the current detection unit 4, and basically, any system may be used therefor. The voltage application unit 3 and the current detection unit 4 may be provided inside the rotation speed estimation device 101. Further, the rotation speed estimation device 101 may include voltage detection means for detecting the voltage vector output by the voltage application unit 3. In this case, the voltage application unit 3 may be configured to transmit a voltage vector command to the processor 901 so as to transmit a numerical value related to the voltage detected by the voltage detection means to the processor 901. The current detection unit 4 may also be configured to transmit a detected numerical value to the processor 901.The processor 901 calculates the estimated angular velocity ω^ r based on the current vector and the voltage vector of the AC motor 2. by the processor 901 performing the calculation of the above-described second angular velocity estimation unit 22, the rotation speed pulsation due to periodic disturbance can be estimated with high accuracy. Note that the processor 901 may also serve as a driving device for the AC motor 2. Specifically, the processor 901 may be configured to not only perform the speed estimation but also calculate a voltage command vector so that an estimated speed has a desired value. Various methods for performing position sensorless torque control are known in the art, including that of the non-patent literature mentioned above.As described above, the rotation speed estimation device for an AC motor according to the first embodiment can estimate the rotation speed pulsation of the AC motor at an appropriate phase regardless of the frequency and achieve higher accuracy for the rotation speed estimation.Furthermore, the speed estimation device for an AC motor according to the first embodiment enables speed estimation with high accuracy even in the case of a high pulsation frequency, which has been a problem in the related art, and also can estimate pulsation in a higher frequency range than in the related art, which is thought to provide a computing unit for increasing the estimation response in a specific frequency band even if no special storage means is provided therefor. Since the compensation phase is obtained in view of the phase characteristic of a closed loop of the angular velocity estimation of the first angular velocity estimation unit which is an adaptive magnetic flux observer, the estimation of the angular velocity can be made at a desired response speed and stable control can be achieved.Second EmbodimentFIG. 12 is a block diagram illustrating a configuration of a rotation speed estimation device 101C according to a second embodiment. In FIG. 12, in the case of the rotation speed estimation device 101C according to the second embodiment, the second angular velocity estimation unit 22 in the configuration of the rotation speed estimation device 101 according to the first embodiment shown in FIG. 7 is replaced with a second angular velocity estimation unit 22C. In the case of the second angular velocity estimation unit 22C, the second angular acceleration estimation unit 30 is replaced with a second angular acceleration estimation unit 30C. In the case of the second angular acceleration estimating unit 30C, the Fourier coefficient calculator 52 is replaced with a Fourier coefficient calculator 52C, and the AC recovery unit 55 is replaced with an AC recovery unit 55C. While the compensation phase θ pls calculated by the compensation phase calculation unit 51 in FIG. 7 is input to the Fourier coefficient calculator 52, the compensation phase θ pls in FIG. 12 is input to the AC recovery unit 55C. Note that the other configuration is the same as or equivalent to that in FIG. 7, and the same or equivalent components are denoted by the same reference numerals, and description thereof will be omitted.The Fourier coefficient calculator 52 of the first embodiment shown in FIG. 7 calculates Fourier coefficients from the equations (12) and (13). On the other hand, the Fourier coefficient calculator 52C of the second embodiment shown in FIG. 12 calculates Fourier coefficients from the following equations (19) and (20). [Formula 19] [Formula 20]Further, the AC recovery unit 55 of the first embodiment shown in FIG. 7 calculates the second estimated angular acceleration ω·^ r2 from the above equation (16). In contrast, the AC recovery unit 55C of the second embodiment illustrated in FIG. 12 calculates the second estimated angular acceleration ω·^ r2 from the following equation (21). [Formula 21]When the ratio of the phases used for calculation using the Fourier coefficient calculator 52 ( 52C) and the AC recovery unit 55 ( 55C) is maintained, the effect of estimating the rotational speed pulsation with an appropriate phase regardless of the frequency mentioned in the first embodiment can be brought about similarly. Thus, the calculation expressed by the equations (19) to (21) can produce the same effect.Note that, similarly to the first embodiment, a configuration in which the cosine coefficient E c' of the model deviation ε and the sine coefficient E s' of the model deviation ε are obtained from the I controllers 53 and 54, respectively, can be adopted in the second embodiment, and the equations (14) and (15) are still the arithmetic expressions thereof without change.Third Embodiment.FIG. 13 is a block diagram illustrating a configuration of a rotation speed estimation device 101D according to a third embodiment. In FIG. 13, in the case of the rotation speed estimation device 101D according to the third embodiment, the first angular velocity estimation unit 21 and the second angular velocity estimation unit 22 in the configuration of the rotation speed estimation device 101 according to the first embodiment shown in FIG. 7 are replaced with a first angular velocity estimation unit 21D and a second angular velocity estimation unit 22D, respectively. In the case of the first angular velocity estimation unit 21D, the integrator 25 is omitted from the configuration of the first angular velocity estimation unit 21, and in the case of the second angular velocity estimation unit 22D, the integrator 31 is omitted from the second angular velocity estimation unit 22. Note that the other configuration is the same as or equivalent to that in FIG. 7, and the same or equivalent components are denoted by the same reference numerals, and description thereof will be omitted.A PI controller 24 included in the first angular velocity estimating unit 21D performs calculation processing expressed by the above equation (5). In other words, the first angular velocity estimation unit 21D generates the first estimated angular velocity ω^ r1 only in the PI control without using an integrator, and outputs the first estimated angular velocity ω^ r1 to the estimated angular velocity calculator 23. Similarly, a second angular acceleration estimation unit 30 included in the second angular velocity estimation unit 22D also generates the second estimated angular velocity ω^ r2 without using an integrator, and outputs the second estimated angular velocity ω^ r2 to the estimated angular velocity calculator 23. Subsequent operation steps are as described in the first embodiment.Since the speed estimation device 101D according to the third embodiment includes the second angular velocity estimation unit 22D, the speed estimation device 101D can estimate high-frequency speed pulsation more accurately than the speed estimation devices of the first and second comparative examples. The reasons for this are as described in the first embodiment.However, the accuracy of the rotation speed estimation in the third embodiment is lower than that in the first embodiment. In contrast, with respect to the amount of calculation required for the calculation for the estimation, the third embodiment is more advantageous because the calculation of the integration is omitted. For this reason, the third embodiment is more preferable in a case where the computing power of the processor 901 illustrated in FIG. 11 is low and the amount of calculation is to be as small as possible. Although details are provided later, a case where rotation pulsation suppression control described in a fifth embodiment is performed is more preferable to configure the rotation speed estimation device 101 according to the first embodiment.Further, for an example similar to the third embodiment, a configuration may be implemented in which the first angular velocity estimation unit 21D includes the integrator 25 and the second angular velocity estimation unit 22D does not include the integrator 31. Alternatively, another configuration may be implemented in which the first angular velocity estimation unit 21D does not include the integrator 25 and the second angular velocity estimation unit 22D includes the integrator 31.Fourth Embodiment.FIG. 14 is a block diagram illustrating a configuration of a rotation speed estimation device 101E according to a fourth embodiment. In FIG. 14, the rotation speed estimation device 101E according to the fourth embodiment includes a second compensation phase calculation unit 56 and a third angular speed estimation unit 33 in addition to the configuration of the rotation speed estimation device 101 according to the first embodiment illustrated in FIG. 1. Further, the estimated angular velocity calculator 23 is replaced with an estimated angular velocity calculator 23E. In other words, in the first to third embodiments, two angular velocity estimation units are provided, but the fourth embodiment relates to a configuration having three angular velocity estimation units. Note that the other configuration is the same as or equivalent to that in FIG. 7, and the same or equivalent components are denoted by the same reference numerals, and description thereof will be omitted.Typically, the characteristics of the angular velocity pulsation included in the rotational angular velocity of an AC motor vary with the application applied to the motor or with a load device connected to the AC motor. In the case where a linked load device has a periodic torque variation, a rotary compressor is considered as an example.FIG. 15 is a diagram illustrating an example of a waveform of a load torque of a rotary compressor. The horizontal axis represents the angle of rotation, the vertical axis the load torque. In the present case, the number of compression spaces in the rotary compressor is represented by k. A rotation angle of 0 to 360 degrees corresponds to a vibration period of a mechanical angle, that is, a mechanical angle period.First, in a case where only one compression space exists, that is, in a case of k=1, the load torque greatly oscillates with the mechanical angle period as shown by the solid curve in FIG. 15. Although second and third harmonics are also included in the load torque waveform, the first order oscillation is the largest. Thus, in a case where a configuration is adopted in the first to third embodiments, the largest first-order angular velocity pulsation can be estimated with high accuracy by setting the disturbance frequency f d, which is used for calculating the second estimated angular velocity ω^ r2 to a primary frequency of the mechanical angular frequency.In the fourth embodiment, a plurality of angular velocity estimation units are provided in parallel. Therefore, the rotation speed pulsation due to second-order and third-order torque fluctuations included in the load torque characteristics can also be estimated with high accuracy. In the example of FIG. 14, the frequency of the rotational speed pulsation to be estimated is used as the second disturbance frequency f d2 which is estimated by the third angular velocity estimation unit 33 and output as the third estimated angular velocity ω^ r3.The same applies to a case where the number of compression spaces is two or three, that is, in the case of k=2 or k=3. As the number of compression spaces is larger, the complexity of the structure and the cost increase, but the waveform has a smaller pulsation as illustrated in FIG. 15. Specifically, in the case of k=2, a second harmonic component of the mechanical angular frequency is large, and in the case of k=3, a third harmonic component is large.In the case of k=2 as an example, the second-order vibration is dominant in the mechanical angle period as illustrated in FIG. 15. For this reason, the disturbance frequency f d input to the second angular velocity estimation unit 22 is set as a secondary frequency of the mechanical angular frequency. Further, when higher-order frequencies than the secondary frequency are to be estimated, these higher-order frequencies may then be input as the second disturbance frequency f d2 to the third angular velocity estimation unit 33.In the case of k=3 as an example, the third-order vibration is dominant in the mechanical angle period as illustrated in FIG. 15. For this reason, the disturbance frequency f d input to the second angular velocity estimation unit 22 is set as the tertiary frequency of the mechanical angular frequency. Further, when higher-order frequencies than the tertiary frequency are to be estimated, these higher-order frequencies may then be input as the second disturbance frequency f d2 to the third angular velocity estimation unit 33.Note that a plurality of angular velocity estimation units are provided in parallel, and in the fourth embodiment, each of the angular velocity estimation units performs phase compensation, but the present invention is not necessarily limited by this example. The phase compensation may be performed by at least one of the angular velocity estimation units, and this single compensation is sufficient to produce the effects inherent in the above-described phase compensation.Fifth Embodiment.FIG. 16 is a block diagram illustrating a configuration of a drive device 102 for an AC motor according to a fifth embodiment. The driving device 102 according to the fifth embodiment is a driving device configured to control the AC motor 2 using the rotation speed estimation device 101, 101C, 101D, or 101E described in the first to fourth embodiments. FIG. 16 illustrates a configuration to which the rotation speed estimation device 101 according to the first embodiment is applied as an example.As illustrated in FIG. 16, the driving device 102 according to the fifth embodiment includes a speed control unit 5, an adder 7, a torque control unit 6, a compensation torque command calculation unit 8 which is a compensation amount calculation unit, and the speed estimation device 101. The compensation torque command calculation unit 8 functions as a "compensation command calculation unit"First, the operation of the compensation torque command calculation unit 8 will be explained. Note that the following description is exemplified for a configuration in which the compensation torque command calculation unit 8 performs calculation on the basis of angular acceleration information calculated by the second angular velocity estimation unit 22.The compensation torque command calculation unit 8 calculates a compensation torque command τ* rip using the following equations (22) to (24). [Formula 22] [Formula 23] [Formula 24]In Equations (22) and (23), K si _ rip represents an integral gain of the compensation torque command calculation unit 8, and T c in the above Equation (22) represents the amplitude of the compensation torque command τ* rip, which corresponds to the cosine component of the pulsation of the angular acceleration, and T s in Equation (23) represents the amplitude of the compensation torque command τ* rip, which corresponds to the sine component of the pulsation of the angular acceleration. As expressed by the above equations (22) and (23), a compensation torque command τ* rip is calculated such that each of the cosine component of the pulsation of the angular acceleration and the sine component of the pulsation of the angular acceleration is zero. The feedback control using this compensation torque command τ* rip can reduce the pulsation of the angular acceleration and hence also reduce the rotation speed pulsation.The reason for using integrating control in equations (22) and (23) is that the property of the controlled object is a proportional property when the compensation torque command τ* rip is obtained based on the angular acceleration. In addition, it is because an ideal closed loop property can be achieved by causing a regulator to have an integrating property and perform feedback control. In the case of a configuration like the second angular velocity estimation unit 22 in which the compensation phase θ pls determined by the compensation phase calculation unit 51 is used, the compensation for the phase of Equation (24) may be made on the basis of the compensation phase θ pls. Alternatively, when the compensation phase θ pls is a compensation phase based on the interference frequency f d the calculation may be performed using an equation other than Equation (24). Although the explanation is not provided because the principle thereof is the same, the above-described calculation of the compensation torque command may be similarly performed using the second estimated angular velocity ω^ r2 calculated by the second angular velocity estimation unit 22.Next, the operation of the speed control unit 5, the torque control unit 6, and the adder 7 will be explained.The speed control unit 5 calculates a basic torque command τ*ω based on an angular speed command of the estimated angular speed ω^ r. The speed control performed by a typical PI controller may be applied to the calculation of the basic torque command τ*ω.The adder 7 adds the compensation torque command τ* rip to the basic torque command τ*ω to calculate a torque command τ* according to the following equation (25). [Formula 25]The torque control unit 6 includes the voltage application unit 3 illustrated in FIG. 11. The torque control unit 6 determines a voltage vector to be applied to the AC motor 2 on the basis of the torque command τ*. The voltage vector may be of a type controlled by electric current control such as, for example. PI control is calculated based on a current command value calculated based on the torque command τ*. Alternatively, an appropriate voltage set point that is dependent on the torque command τ* may be stored in the memory 902 and obtained directly based on the torque command τ*.The driving device 102 according to the fifth embodiment can reduce a compensation torque command for reducing the rotational speed pulsation on the basis of information on the angular speed pulsation obtained by the rotational speed estimation device 101. This brings about an effect of reducing uneven rotation of the AC motor 2.Although FIG. 16 illustrates a configuration including the compensation torque command calculation unit 8 that calculates the compensation torque command τ* rip the present invention is not limited to this configuration. Another configuration may be implemented in which a compensation current command calculation unit that calculates a compensation current command is used instead of the compensation torque command calculation unit 8. In the case of this configuration, an adder and a current control unit are provided in a subsequent stage of the torque control unit 6. The adder adds a basic current command generated by the torque control unit 6 to the compensation current command calculated by the compensation current command calculation unit to generate a current command. The current control unit determines a voltage vector to be applied to the AC motor 2 based on the current command output from the adder. Subsequent steps of operation are as described above.Sixth Embodiment.FIG. 17 is a block diagram illustrating a configuration of a drive device 102A for an AC motor according to a sixth embodiment. In FIG. 17, the AC motor 2 illustrated in FIG. 16 is replaced with a refrigerant compressor 2 athat includes the AC motor 2. The driving device 102A according to the sixth embodiment is configured to reduce the rotation speed pulsation of the refrigerant compressor 2 ausing the rotation speed estimation device 101 according to the first embodiment. FIG. 17 illustrates a configuration to which the rotation speed estimation device 101 according to the first embodiment is applied; however, the present invention is not limited to this example. The driving device 102A can be configured using each of the rotation speed estimation devices 101C, 101D, and 101E described in the second to fourth embodiments. Note that the configurations and functions of the rotation speed estimation devices 101, 101C, 101D, and 101E are as described above, and therefore, the description thereof will be omitted in this part.Next, the structure of the refrigerant compressor 2 aand a load torque in the refrigerant compressor 2 awill be described in detail with reference to FIGS. 18 and 19. FIG. 18 is a cross-sectional view illustrating a schematic structure of the inside of the refrigerant compressor 2 aillustrated as a driven object in FIG. 17. Further, FIG. 19 is a cross-sectional view illustrating a structure of the inside of a compression unit 202 of the refrigerant compressor 2 aillustrated in FIG. 18. Note that a refrigerant compressor referred to as a rotary compressor of the rotary piston type will be described herein, but the present invention is not limited to this example. The refrigerant compressor can also be of another compressor type, for example that of a scroll compressor.The refrigerant compressor 2 aincludes an airtight container 211, the AC motor 2 accommodated in the airtight container 211, a shaft 201 having one end passing through a rotor 2- 1 constituting the AC motor 2, the compression unit 202 through which the other end of the shaft 201 passes and which is fixed to the inside of the airtight container 211, an inflow pipe 203 provided to the airtight container 211, and an outflow pipe 204 provided to the airtight container 211.A stator 2-2 of the AC motor 2 is supported on and held by the airtight container 211 by shrink fitting, freeze fitting or welding. Electric power is supplied to a coil 2- 3 on the stator 2- 2 via an electric wire, which is not shown. The rotor 2- 1 is disposed inside the stator 2- 2 with a gap 2- 4 therebetween, and is rotatably supported by a bearing, which is not illustrated, via a shaft 201 located at the center of the rotor 2- 1.In the refrigerant compressor 2 ahaving the above-described configuration, when the AC motor 2 is driven, refrigerant drawn into the compression unit 202 via the inflow pipe 203 is compressed, and the compressed refrigerant is discharged from the discharge pipe 204. The refrigerant compressor 2 a often has a structure in which the AC motor 2 is immersed in the refrigerant, and because of large temperature variations thereon, it is difficult to attach a position sensor to the AC motor 2. For this reason, in the case of the refrigerant compressor 200, the AC motor 2 needs to be driven in a driving manner without a position sensor.As illustrated in FIG. 19, the compression unit 202 includes an annular cylinder 212, a piston 205 that is formed rotatably and integrally with the shaft 201 and is located inside the cylinder 212, and a compression space 213 provided in an inner circumferential part of the cylinder 212.The cylinder 212 has an inlet 206 communicating with the inflow pipe 203 illustrated in FIG. 18, and an outlet 207 through which the compressed refrigerant is discharged to the outside. The inlet 206 and the outlet 207 communicate with the compression space 213. The cylinder 212 includes a flap 210 that divides the compression space 213 into a low pressure space communicating with the inflow pipe 203 and a high pressure space communicating with the outlet 207, and a spring 209 that is set to activate the flap 210.The shaft 201 connects the AC motor 2 and the piston 205 to each other. The piston 205 is eccentric, so that the capacities on the suction side and the discharge side change depending on the rotation angle. The refrigerant drawn through the inlet 206 is compressed by the piston 205. When the pressure in the compression space 213 rises, a relief valve 208 opens and the refrigerant is discharged through the outlet 207. When the refrigerant is discharged, refrigerant simultaneously flows into the suction side. When the rotation of the AC motor 2 is continued, the refrigerant is discharged once per revolution at the mechanical angle of the piston 205.The load torque pulsation of the refrigerant compressor 2a corresponds to the periodic disturbance in the case of the AC motor 2, making it a factor for the rotational speed pulsation. It is generally known that a larger rotational speed pulsation in the refrigerant compressor 2 acauses amplified noises and vibrations.An important aspect is that the frequencies of the load torque pulsation and the rotational speed pulsation are predefined by the structure of the refrigerant compressor 2 aand are thus known in advance. In the case of the refrigerant compressor 2a according to the sixth embodiment, the control system shown in FIG. 17 is constructed in favor of this aspect. The refrigerant compressor 2 aestimates a specific frequency component of the rotational speed pulsation with high accuracy in the second angular velocity estimation unit 22, and calculates such a compensation torque command τ* rip, which suppresses the pulsation, which is performed in the compensation torque command calculation unit 8. As a result, the rotation speed pulsation can be reduced without pretreatment. Since the pretreatment is unnecessary, the cost of the treatment before shipping can be significantly reduced, which then brings about a great usefulness.Seventh Embodiment.FIG. 20 is a diagram illustrating a configuration of a refrigeration cycle device according to a seventh embodiment. The refrigeration cycle device 300 illustrated in FIG. 20 includes the driving device 102 for an AC motor, the refrigerant compressor 2 a, a condenser 301 connected to the refrigerant compressor 2 avia a line 305, a liquid receiver 302 connected to the condenser 301 via the line 305, an expansion valve 303 connected to the receiver 302 via the line 305, and an evaporator 304 connected to the expansion valve 303 via the line 305. The evaporator 304 is connected to the supply pipe 203.By the refrigerant compressor 2 a, the condenser 301, the liquid receiver 302, the expansion valve 303, the evaporator 304, and the inflow pipe 203 being connected to each other through the pipe 305, the refrigerant compressor 2 a, the condenser 301, the liquid receiver 302, the expansion valve 303, the evaporator 304, and the inflow pipe 203 constitute a refrigeration cycle structure 306 in which the refrigerant circulates. In the refrigeration cycle assembly 306, processes of evaporating, compressing, condensing, and expanding the refrigerant are repeated, and heat is transferred while the refrigerant is repeatedly changed from liquid to gas and from gas to liquid.The functions of the devices constituting the refrigeration cycle device 300 will be explained. The evaporator 304 evaporates liquid refrigerant in a low pressure state, extracts heat from the environment, and thus has a cooling effect. The refrigerant compressor 2a compresses gaseous refrigerant to high pressure gas to let the refrigerant condense. The refrigerant compressor 2 ais driven by the driving device 102A according to the sixth embodiment. The condenser 301 releases the heat to condense the gaseous refrigerant under high pressure into liquid refrigerant. The expansion valve 303 subjects the liquid refrigerant to the throttle expansion into low-pressure liquid to evaporate the refrigerant. The liquid receiver 302 is provided for adjusting the amount of refrigerant to be circulated, and may be omitted in the case of a compact device.Typically, an improvement in quietness and cost reduction is required for a refrigeration cycle device. In the case of a refrigeration cycle device for household use, particularly high demands are made with regard to cost reduction, which is why a single rotary compressor is often used. A single rotary compressor is a rotary compressor described in FIGS. 18 and 19, which is a compressor of a type including only a compression space 213. A rotary compressor is accompanied by a significantly high load torque pulsation and therefore tends to cause strong vibrations and loud noises. On the other hand, complicated adjustments to control in a feedforward control system in the related art have required reduction of vibration and noise.The refrigeration cycle device 300 according to the seventh embodiment performs feedback control so that the drive device 102A automatically brings the rotation speed pulsation to zero. As a result, the cost of adjustments prior to shipping can be significantly reduced. Further, according to the seventh embodiment, the speed pulsation is reduced by feedback control, thereby enabling a flexible response to manufacturing-related deviations, variations in motor constant, and changes in load conditions of the compressor. Accordingly, the refrigeration cycle device 300 having higher environmental resistance can be achieved.The configurations set forth in the above embodiments are examples of contents of the present invention, and may be respectively combined with other prior arts and partially omitted and / or modified without departing from the scope of the present invention.List of reference characters2 AC motor; 2a refrigerant compressor; 3 voltage applying unit; 4 current detecting unit; 5 speed control unit; 6 torque control unit; 7 adder; 8 compensation torque command calculating unit; 11 model deviation calculating unit; 12 state estimator; 13 subtractor; 14 deviation calculator; 21 first angular velocity estimating unit; 22, 22B, 22C, 22D second angular velocity estimating unit; 23 estimated angular velocity calculator; 24, 27, 28 PI controller; 25, 31, 32 integrator; 26, 52 Fourier coefficient calculator; 29, 55 AC restoration unit; 30, 30B, 30C second angular acceleration estimating unit; 33 third angular velocity estimating unit; 51 compensation phase calculating unit; 53, 54I controller; 56 second compensation phase calculating unit; 101, 101- 1, 101A, 101B, 101C, 101D, 101E speed estimation device; 102 driving device; 200 refrigerant compressor; 201 shaft; 202 compression unit; 203 inflow pipe; 204 outlet pipe; 205 piston; 206 inlet; 207 outlet; 208 discharge valve; 209 spring; 210 flap; 211 airtight container; 212 cylinder; 213 compression space; 300 refrigeration cycle device; 301 condenser; 302 liquid receiver; 303 expansion valve; 304 evaporator; 305 pipe; 306 refrigeration cycle assembly; 901 processor; 902 memory.

Claims

A speed estimation device (101, 101C, 101D, 101E) for an AC motor (2), the speed estimation device (101, 101C, 101D, 101E) comprising: a model deviation calculation unit (11) for calculating a model deviation based on a voltage, a current, and an estimated angular velocity of the AC motor (2); a first angular velocity estimation unit (21) for calculating a first estimated angular velocity based on the model deviation; a second angular velocity estimation unit (22) for calculating a second estimated angular velocity based on the model deviation, the second estimated angular velocity being different in frequency from the first estimated angular velocity; a compensation phase calculation unit (51) for calculating a compensation phase based on a disturbance frequency; and an estimated angular velocity calculator (23) for calculating an estimated angular velocity of the AC motor (2) based on the first and second estimated angular velocities, wherein one of the first and second estimated angular velocities is calculated based on the compensation phase.The rotational speed estimation device (101, 101C, 101D, 101E) for an AC motor (2) according to claim 1, wherein the first estimated angular speed has a frequency lower than a frequency of the second estimated angular speed, the first angular speed estimation unit (21) calculates the first estimated angular speed on the basis of the model deviation, and the second angular speed estimation unit (22) calculates the second estimated angular speed on the basis of the model deviation, the compensation phase, and the disturbance frequency.The rotation speed estimation device (101, 101C, 101D, 101E) for an AC motor (2) according to claim 2, wherein the compensation phase calculation unit (51) calculates the compensation phase in view of a phase characteristic of the first angular velocity estimation unit (21).The rotational speed estimation device (101) for an AC motor (2) according to any one of claims 1 to 3, wherein the second angular velocity estimation unit (22) includes: a specific frequency extractor (52) for extracting a specific frequency component of the model deviation based on the disturbance frequency and the compensation phase; and a specific frequency angular velocity estimator (53, 54, 55) for calculating the second estimated angular velocity based on the specific frequency component.The rotational speed estimation device (101C) for an AC motor (2) according to any one of claims 1 to 3, wherein the second angular velocity estimation unit (22C) includes: a specific frequency extractor (52C) for extracting a specific frequency component of the model deviation based on the disturbance frequency; and a specific frequency angular velocity estimator (53, 54, 55C) for calculating the second estimated angular velocity based on the specific frequency component and the compensation phase.The rotational speed estimation device (101) for an AC motor (2) according to any one of claims 1 to 3, wherein the first angular velocity estimation unit (21) includes: a first angular acceleration estimator (24) for calculating a first estimated angular acceleration from the model deviation; and a first angular velocity calculator (25) for calculating the first estimated angular velocity from the first estimated angular acceleration, and the second angular velocity estimation unit (22) includes: a specific frequency extractor (52) for extracting a specific frequency component of the model deviation based on the disturbance frequency and the compensation phase; a specific frequency angular acceleration estimator (53, 54, 55) for calculating a second estimated angular acceleration based on a specific frequency component of the model deviation; and a second angular velocity calculator (31) for calculating the second estimated angular velocity from the second estimated angular acceleration.The rotational speed estimation device (101E) for an AC motor (2) according to any one of claims 1 to 6, comprising: at least one other second angular velocity estimation unit configured similarly to the second angular velocity estimation unit (22), wherein at least one of the second angular velocity estimation units calculates the second estimated angular velocity based on the compensation phase.A driving apparatus (102) for an AC motor (2), the driving apparatus (102) comprising: the rotation speed estimating apparatus (101, 101C, 101D, 101E) for an AC motor (2) according to any one of claims 1 to 7, wherein the driving apparatus (102) determines a voltage to be applied to the AC motor (2) on the basis of a current flowing in the AC motor (2) and the angular velocity estimated by the rotation speed estimating apparatus (101, 101C, 101D, 101E).The driving device (102) for an AC motor (2) according to claim 8, further comprising: a compensation command calculation unit (8) for calculating a compensation current command or a compensation torque command based on an angular velocity or an angular acceleration calculated by the second angular velocity estimation unit (22).A refrigerant compressor (2a) comprising: the driving device (102) for an AC motor (2) according to claim 8 or 9; an AC motor (2) to which a voltage is applied by the driving device (102); and a compressing unit (202) in which refrigerant is compressed by the AC motor (2).A refrigeration cycle device (300) comprising the refrigerant compressor (2a) according to claim 10.

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