Control device for bearingless motor, motor system, and control method for bearingless motor

Abstract

A control device (30) for a bearingless motor, which controls the bearingless motor provided with a rotor and a stator having a motor winding for generating torque, the rotor and the stator being disposed with a predetermined gap therebetween, is provided with an observer (32) and a speed estimator (33). The observer (32) determines a voltage detection value based on a voltage command value of the motor winding or a voltage detection value that is a detection value of a voltage applied to the motor winding. At least one of an estimated current, which is an estimated value of a current flowing in the bearingless motor, and an estimated rotor magnetic flux, which is an estimated value of a rotor magnetic flux generated in a motor winding by a rotor, is calculated. The speed estimator (33) calculates and outputs an estimated axial speed, which is an estimated value of the axial speed of the rotor, using as input at least one of a current error, which is a difference between the estimated current and a current detection value, which is a value of the current of the motor winding, and an estimated rotor magnetic flux.

Description

Technical Field

[0001] The present invention relates to a control device, a motor system and a control method for a bearingless motor in which a rotor is supported by magnetic levitation without contact with a stator and rotates. Background Art

[0002] The bearingless motor has the function of a motor that generates torque and the function of a magnetic bearing that generates a supporting force for the rotor to float non-contact with the stator on the same magnetic circuit. In order to float the rotor, all five degrees of freedom except the rotating axis need to be actively controlled, or some of them need not be actively controlled but passively set to a stable structure.

[0003] In a 2-axis control type bearingless motor, in the radial direction, specifically only in the two directions of the X-axis and the Y-axis that are orthogonal to each other, the position is detected by a sensor, and the support force is adjusted so that the detected position is consistent with the target position, thereby actively controlling the 2-axis direction. The rotor is usually arranged with a gap portion in the radial direction relative to the stator. Regarding the axial direction of the 2-axis control type bearingless motor, the axis perpendicular to both the X-axis and the Y-axis, that is, the Z-axis and the tilt direction (θx, θy), are usually not actively controlled, and are passively set to a stable structure. Below, the direction in which control is performed is referred to as the control direction. On the other hand, the direction that is not controlled and passively becomes stable is referred to as the passive stable direction. In order to passively set it to be stable, the attraction between the permanent magnet of the rotor and the iron core of the stator is used. In one example, when the rotor is displaced in the axial direction, a magnetic flux flows between the permanent magnet of the rotor and the iron core of the stator separated by the radial gap portion to generate a force that attracts each other, so as to act in a way that the axial displacement of the rotor is returned. As a result, a restoring force is generated in the opposite direction of the axial displacement without control. The attractive force acting between the permanent magnet and the core is proportional to the distance, so it can be considered as a spring force. Hereinafter, the ratio of the restoring force [N] to the axial displacement [m] is called the restoring force coefficient k z [N / m].

[0004] In the axial direction of the 2-axis control type bearingless motor, stability is ensured only by the above-mentioned restoring force generated by the radial gap portion, so it lacks stability compared to the control direction. In addition, the restoring force does not have the effect of attenuating vibration. The damping force that has the effect of attenuating vibration in proportion to the speed is not generated in the passive stability direction in principle. Therefore, the vibration in the passive stability direction sometimes continues or diverges and becomes unstable.

[0005] Patent document 1 proposes a method of passing an excitation current through the winding of the teeth of a stator that is radially spaced apart from a rotor by a gap, thereby controlling the axial position of the rotor. In the technology described in patent document 1, the rotor and the stator have surface portions that are not opposite to each other in the axial direction, a displacement sensor detects the axial position of the rotor, and a control device generates an excitation current command for controlling the axial position of the rotor based on the position information detected by the displacement sensor. In the technology described in patent document 1, an axial force is generated in the rotor by the magnetic flux generated by the excitation current flowing through the winding arranged between the teeth of the stator protruding toward the rotor side and the magnetic flux generated by the permanent magnet.

[0006] Patent Document 1: Japanese Patent Application Publication No. 2015-171165 Summary of the invention

[0007] In order to control the position of the rotor in the axial direction, an axial displacement sensor or a sensor that can measure the velocity or acceleration that can calculate the displacement is required. If the acceleration is integrated, it becomes the velocity, and if the velocity is integrated, it becomes the displacement. In addition, if the displacement is differentiated, it becomes the velocity, and if the velocity is differentiated, it becomes the acceleration. If at least one of the displacement, velocity, and acceleration can be detected, the remaining other physical quantities can also be calculated. In the technology described in Patent Document 1, a sensor that detects the position using the rotor shaft as a sensor target is arranged on the shaft end side. At this time, the structure is extended in the axial direction by the amount of the sensor, so the volume increases. In addition, the side where the sensor is set in the two directions in which the shaft extends physically interferes with the sensor, so there is the following problem, that is, it is difficult to connect the shaft to a load such as a fan. In addition, in the technology described in Patent Document 1, the sensor is used in the above manner, so the increase in cost caused by the use of the sensor, the failure of the sensor, the disconnection of the signal line connected to the sensor, or the change in sensor characteristics or the increase in error caused by temperature changes become a problem.

[0008] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a control device for a bearingless motor that has a simpler structure than conventional devices and can estimate the axial displacement, velocity, or acceleration of a rotor.

[0009] In order to solve the above-mentioned problems and achieve the purpose, the control device of the bearingless motor involved in the present invention controls the bearingless motor which has a rotor and a stator having a motor winding that generates torque, and the rotor and the stator are arranged with a predetermined gap, and has an observer and a speed estimator. The observer calculates at least one of the estimated value of the current flowing in the bearingless motor, i.e., the estimated current, and the estimated value of the rotor magnetic flux generated in the motor winding through the rotor, i.e., the estimated rotor magnetic flux, based on the voltage command value of the motor winding or the detected value of the voltage applied to the motor winding, i.e., the voltage detection value. The speed estimator takes as input at least one of the difference between the estimated current and the value of the current of the motor winding, i.e., the current detection value, i.e., the current error, and the estimated rotor magnetic flux, and calculates and outputs the estimated value of the axial speed of the rotor, i.e., the estimated axial speed.

[0010] Effects of the Invention

[0011] The control device for a bearingless motor according to the present invention has the effect of being able to estimate the axial displacement, velocity, or acceleration of the rotor while simplifying the structure compared with the related art. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a cross-sectional view schematically showing an example of the structure of the bearingless motor according to the first embodiment.

[0013] Figure 2 This is a block diagram showing an example of the configuration of a control device for a bearingless motor according to the first embodiment.

[0014] Figure 3 1 is a block diagram showing an example of the configuration of a velocity estimator that takes a current error as input and outputs an estimated axial velocity.

[0015] Figure 4 1 is a block diagram showing an example of the configuration of a velocity estimator that takes a current error as input and outputs an estimated axial velocity.

[0016] Figure 5 1 is a block diagram showing an example of the configuration of a velocity estimator that takes a current error as input and outputs an estimated axial velocity.

[0017] Figure 6 1 is a block diagram showing an example of the configuration of a velocity estimator that takes a current error as input and outputs an estimated axial velocity.

[0018] Figure 7 1 is a block diagram showing an example of the configuration of a velocity estimator that takes a current error as input and outputs an estimated axial velocity.

[0019] Figure 8This is a block diagram showing an example of the configuration of a control device for a bearingless motor according to the second embodiment.

[0020] Fig. 9 This is a block diagram showing an example of the configuration of a d-axis current command value generator in the bearingless motor control device according to the third embodiment.

[0021] Fig.10 This is a block diagram showing an example of the configuration of a d-axis current command value generator in the bearingless motor control device according to the third embodiment.

[0022] Fig.11 This is a block diagram showing an example of the configuration of a speed estimator of a control device for a bearingless motor according to a fourth embodiment.

[0023] Fig.12 This is a block diagram showing an example of the configuration of a control device for a bearingless motor according to a fourth embodiment.

[0024] Fig.13 This is a block diagram showing an example of the configuration of a speed estimator used in the control device for a bearingless motor according to the fourth embodiment.

[0025] Fig.14 This is a block diagram showing an example of the configuration of a speed estimator used in the control device for a bearingless motor according to the fourth embodiment.

[0026] Fig.15 This is a block diagram showing an example of the configuration of a control device for a bearingless motor according to the fifth embodiment.

[0027] Fig.16 This is a block diagram showing an example of the configuration of a control device for a bearingless motor according to the sixth embodiment.

[0028] Fig.17 This is a diagram showing an example of a hardware configuration for realizing a control device for a bearingless motor according to the first to sixth embodiments. DETAILED DESCRIPTION

[0029] Hereinafter, a control device for a bearingless motor, a motor system, and a control method for a bearingless motor according to embodiments of the present invention will be described in detail with reference to the drawings.

[0030] In the following embodiments, when a character represents a vector, it is labeled as "character (vector)", and when a character represents a matrix, it is labeled as "character (matrix)". In addition, for characters marked by a symbol attached to the top in the formula, they are labeled as "character (symbol attached to the top)" in the text. In one example, a character with "^" attached to the top is labeled as "character ^".

[0031] Implementation method 1.

[0032] Figure 1 1 is a cross-sectional view schematically showing an example of the structure of the bearingless motor according to Embodiment 1. Here, the axial direction of the rotor 20 is defined as the z-axis, and two axes perpendicular to each other on a plane perpendicular to the z-axis are defined as the x-axis and the y-axis. Figure 1 The zx section of the bearingless motor 1 is shown. The bearingless motor 1 has a stator 10 and a rotor 20 .

[0033] The stator 10 has a stator core 11, a motor winding 12, and a support winding 13. The stator core 11 is a generally cylindrical shape surrounding the central axis CA of the bearingless motor 1. The central axis CA is the rotation center of the rotor 20 in the bearingless motor 1, and in one example, is a virtual straight line passing through the center of the rotor 20. The central axis CA is an example of a rotation axis. Hereinafter, the extending direction of the central axis CA is also referred to as the axial direction. In addition, in Figure 1 , the central axis CA is oriented in the vertical direction. The motor winding 12 is provided in the slots of the stator core 11 to rotate the rotor 20, that is, to generate torque. The support winding 13 is provided in the slots of the stator core 11 for magnetic suspension.

[0034] The rotor 20 has a shaft 21 and a permanent magnet 22. In one example, the shaft 21 is a cylindrical member made of a magnet. The shaft 21 has the z-axis as the rotation axis. The diameter of the shaft 21 in the direction perpendicular to the z-axis is smaller than the inner diameter of the stator core 11. The permanent magnet 22 is arranged on the outer periphery of the shaft 21. The permanent magnet 22 can be fixed to the shaft 21 by magnetic force, but can also be fixed by a fixing member such as an adhesive. In addition, Figure 1 , a bearingless motor 1 of a surface magnet type (Surface Permanent Magnet: SPM) in which a permanent magnet 22 is embedded on the surface of a shaft 21 is shown, but a bearingless motor 1 of an interior magnet type (Interior Permanent Magnet: IPM) in which a permanent magnet 22 is embedded inside the core of the shaft 21 may also be used. The stator 10 and the rotor 20 are arranged with a predetermined gap therebetween. In this example, the rotor 20 is provided on the inner side of the cylindrical stator 10 and is separated from the inner circumference of the stator 10 by a predetermined gap.

[0035] By passing a current through the motor winding 12 of the stator 10, a magnetic flux with a pole number of p is generated, and a torque is generated. By passing a current through the support winding 13 of the stator 10, a magnetic flux with a pole number of p±2 or 2 is generated, and a support force in the radial direction is generated. In the case of a general bearingless motor including a surface magnet type bearingless motor, a support force is generated by a magnetic field with a pole number of p±2 generated by the support winding 13. In the case of a commutated pole type bearingless motor or a unipolar type bearingless motor, a support force is generated by a magnetic field with a pole number of 2 generated by the support winding 13.

[0036] At least a portion of the magnetic circuit of the magnetic flux of the pole number p for generating torque and the magnetic circuit of the magnetic flux of the pole number p±2 or 2 for generating the supporting force are shared. At least a portion of the magnetic circuit is shared, and the magnetic flux of the pole number p±2 or 2 is superimposed on the magnetic flux of the pole number p, thereby generating sparseness and density in the magnetic flux density. Therefore, by adjusting the magnitude and phase of the supporting current, the magnitude and direction of the supporting force in the radial direction can be controlled.

[0037] If the gravitational acceleration is g and the mass of the rotor 20 is m, the deadweight mg always acts downward on the rotor 20. When the rotor 20 is located on the lower side in the axial direction, that is, on the negative side in the z-axis direction, an axial restoring force F acts upward from the stator 10. z Moreover, in terms of self-weight mg and restoring force F z The rotor 20 floats at the equilibrium position. Figure 1 As shown in FIG. 1 , when the z-axis is arranged in a manner facing the vertical direction, the rotor 20 becomes a balanced position after being displaced downward from the axial magnetic center, i.e., the position z=0. On the other hand, when the rotor 20 is displaced axially upward, i.e., in the positive direction of the z-axis, the restoring force F z Same as deadweight, facing downward.

[0038] In addition, although not shown in the figure, a fan or the like is sometimes installed on the rotor 20. In this case, the reaction when the air or the like is circulated by the fan acts on the axial direction of the rotor 20. As a result, the balanced position in the axial direction of the rotor 20 also changes. This reaction also occurs when the axial direction of the rotor 20 is horizontal. That is, when the central axis CA of the rotor 20 is in the horizontal direction, the balanced position may also shift from the axial magnetic center.

[0039] Figure 1 An inner rotor type bearingless motor 1 in which the rotor 20 is located inside the stator 10 is shown, but the same phenomenon occurs in an outer rotor type in which the rotor 20 is located outside the stator 10, and the technology of the embodiment described below can be applied to the outer rotor type bearingless motor 1.

[0040] Figure 21 is a block diagram showing an example of the structure of the control device of the bearingless motor involved in Embodiment 1. Here, the bearingless motor 1 is set as the plant 40 to be controlled, and the observer 32 that takes the voltage as input and the speed estimator 33 that takes the current error as input and outputs the estimated axial speed are shown. The thin lines in the figure are index quantities, and the thick lines are vectors, and the same applies to the following block diagrams.

[0041] Figure 1 The bearingless motor 1 shown is composed of Figure 2 The control is performed by a control device 30 shown. The control device 30 includes a current controller 31, an observer 32, and a speed estimator 33. The motor system includes the bearingless motor 1 and the control device 30.

[0042] The current controller 31 controls the current i flowing in the motor winding 12 of the bearingless motor 1 as the complete plant 40. s (Vector) The current detection value detected by the current detector (not shown) for detection and the current command value i to the motor winding 12 of the stator 10 d * 、i q * In a consistent manner, the voltage command value v is output as the voltage command value applied to the motor winding 12. s * (Vector). Figure 2 In the example, the current command value in the d-axis direction, i.e., the d-axis current command value i d * The deviation of the d-axis current id, which is the value of the current in the d-axis direction as the output of the plant 40, and the q-axis current command value i, which is the current command value in the q-axis direction q * and the value of the current in the q-axis direction as the output of the plant 40, that is, the q-axis current i q The voltage command value v in the d-axis direction is outputted so that the deviations of d and the voltage command value v in the q-axis direction q Here, the subscript s is the designator 10. The subscript d refers to the d-axis, and the subscript q refers to the q-axis. The superscript * refers to the command value. In addition, the input Figure 2 The voltage v of the observer 32 s (Vector) can be a voltage detection value or a voltage command value. The voltage detection value refers to the value of the voltage applied to the motor winding 12 of the stator 10 detected by a sensor such as a voltage sensor, but the voltage command value can also be used without using a sensor. Considering both the voltage detection value and the voltage command value, Figure 2 There is no superscript * in the text and it is abbreviated as v s(Vector) The same also applies to other embodiments and the drawings described.

[0043] The observer 32 is based on the voltage command value v s * (vector), the estimated value of the current flowing in the bearingless motor 1, that is, the estimated current i s ^(vector) and the rotor flux Φ generated by the rotor 10 in the motor winding 12 r The estimated value of (vector) is the estimated rotor flux Φ r In the first embodiment, the observer 32 calculates the voltage command value v output from the current controller 31. s *(vector) is used as input, and the estimated value of the state variable of the bearingless motor 1 as the complete set 40 is calculated, and the calculation model that estimates the current flowing in the motor winding 12 of the bearingless motor 1 is estimated. That is, the observer 32 is a calculation model that reproduces the action of the bearingless motor 1. Therefore, it is possible to estimate the value of the current, magnetic flux, etc. that are the output and state variables of the observer 32 without using a detector for calculation. In addition, it is also possible to compare the estimated value with the detected value, perform calculations, and obtain the difference. However, the observer 32 is set so that the rotor 20 of the bearingless motor 1 does not move in the axial direction, and the calculation is performed by estimation. The current flowing in the motor winding 12 estimated by the observer 32 is called the estimated current i s ^ (vector), with a cap "^". In addition, the observer 32 outputs the estimated current i s ^ (vector) and the current detection value i detected by the current detector s The difference between the vectors is the current error Δi s (Vector).

[0044] The speed estimator 33 calculates the current error Δi s (vector) and estimated rotor flux Φ r The axial speed of the rotor 20 is estimated by using at least one of the vectors d|z^| and the value obtained from the value calculated by the observer 32 as an input. The axial speed estimated by the speed estimator 33 is referred to as an estimated axial speed d|z^| / dt.

[0045] The axial position z of the rotor 20 is calculated based on the axial motion equation of the rotor 20. Figure 2 The axial motion model 41 shows the axial motion equations of the rotor 20. The axial motion equations of the rotor 20 are expressed as the following equations (1) and (2).

[0046] [Formula 1]

[0047]

[0048] F z =-mg-(k z0 +k zi i d )z··· (2)

[0049] The ratio of the restoring force to the displacement is the stiffness. The stiffness is a constant value k when the current is not controlled. z0 But if the d-axis current i d In other words, the attraction force generated between the stator core 11 and the permanent magnet 22 of the rotor 20 can be increased or decreased. zi is the d-axis current i d The ratio of the rigidity change is k. z0 +k zi i d .

[0050] The plant 40 to be controlled is a bearingless motor 1, and the input voltage is set to v s (vector) = [v d v q ] T , the output is set to current i s (vector) = [i d i q ] T . Where T refers to transpose.

[0051] In addition, the variable which represents the state between the input and output of the set 40 is called a state variable. Among the state variables, there is the armature reaction flux Φ s (vector) = [Φ ds Φ qs ] T and rotor flux Φ r (vector) = [Φ dr Φ qr ] T Here, the subscript r refers to the rotor 20. The armature reaction flux Φ s (vector) and rotor flux Φ r (Vector) each has two components, so the total number of state variables is 4.

[0052] In addition, as shown in the following equation (3), the armature reaction flux Φ s (vector) and the current i observed in the motor winding 12 of the stator 10 s (vector) is in proportional relationship. Therefore, even if the armature reaction flux Φ is not used in the state variable s (vector), but uses the current i observed in the motor winding 12 s(vector), the elements of a part of the matrix constituting the state equation described later are also set to only constant multiples of 1 / L based on the following formula (3), and the essence of the formula is almost unchanged.

[0053] [Formula 2]

[0054] Φ s =Li s …(3)

[0055] The current i observed in the motor winding 12 of the stator 10 s (Vector) is a three-phase system consisting of U phase, V phase, and W phase, but it can be converted into current on the rotating dq axis by performing uvw-dq transformation. u 、i v 、i w Converted to d-axis current i d and q-axis current i q The formula is the following formula (4). Here, θ is the angle of the rotating dq axis relative to the stationary coordinate, that is, the rotation angle.

[0056] [Formula 3]

[0057]

[0058] When the true rotation angle θ is unknown, the estimated rotation angle θ^, which is an estimated value of the rotation angle, can be used for conversion. u 、i v 、i w The estimated rotation angle θ is converted into the d-axis current i d and q-axis current i q In the case of , the following equation (5) is obtained. In addition, the values ​​on the left side at this time become the estimated current values ​​on the d-axis and the estimated current values ​​on the q-axis.

[0059] [Formula 4]

[0060]

[0061] In addition, Figure 2 In the example, the current i output by the complete set 40 is s (Vector) is converted into the current on the dq axis, that is, it shows i s (vector) = [i d i q ] T That is, in Figure 2 In the figure, the module for converting the three-phase current into dq axes is omitted.

[0062] As described above, the output of the plant 40, i.e., the current i s(vector) = [i d i q ] T Feedback is performed to respectively control the d-axis current command value i d * and q-axis current command value i q * The deviation is calculated and input to the current controller 31. d and d-axis current command value i d * The deviation of the current value deviation calculation unit 34d is executed, and the q-axis current i q and q-axis current command value i q * The current value deviation calculation unit 34q calculates the deviation of the current value. Then, the current controller 31 outputs the voltage command value v so that the deviation is set to 0. s * (vector) = [v d * v q * ] T .

[0063] In addition, the inverter follows the voltage command value v s * (vector) voltage is applied to the plant 40. In fact, voltage is applied to each winding of the U phase, V phase and W phase, but Figure 2 The uvw-dq transformation module is omitted in the figure, and the values ​​on the dq coordinates are directly shown. Figure 2 The inverter is omitted in the illustration.

[0064] The observer 32 is configured to calculate the voltage v applied to the stator 10. s (vector) as input, the estimated value of the state variable of the plant 40, namely the estimated armature reaction flux Φ s ^(vector) and estimated rotor flux Φ r ^ (vector) is calculated to calculate the current i flowing in the motor winding 12 of the stator 10 s The observer 32 estimates and outputs the current error Δi according to the following equation (6): s (vector) to perform calculations.

[0065] [Formula 5]

[0066]

[0067] As described above, the speed estimator 33 calculates the current error Δi s (vector) As input, the estimated axial velocity d|z^| / dt of the rotor 20 is estimated.

[0068] In addition, the voltage input to the observer 32 may be a voltage command value v s * (vector), can also be the voltage detection value v s (vector). When the input voltage command value v s * In the case of (vector), no voltage sensor is required, and the structure can be simplified. s In the case of (vector), the voltage command value v caused by the dead time etc. can be eliminated. s * (vector) and voltage detection value v s (vector) error.

[0069] As described above, the estimated axial velocity d|z^| / dt of the rotor 20 can be estimated without providing a displacement sensor, a velocity sensor, or an acceleration sensor for detecting the axial position of the rotor 20. As described above, the estimated axial velocity d|z^| / dt can be estimated by integrating the remaining physical quantity, i.e., the displacement, and differentiating the acceleration based on the estimated velocity. In addition, by configuring the voltage command value v s * (vector) is input to the observer 32, so that the voltage sensor can be eliminated. In this case, the only sensor required is the current sensor. That is, there is no need to newly provide hardware such as a sensor required for estimating the axial displacement, velocity or acceleration.

[0070] Here, the processing in the speed estimator 33 will be described. The observer 32 estimates that the rotor 20 of the bearingless motor 1 does not move in the axial direction, and the speed estimator 33 calculates the speed of the rotor 20 based on the estimated current i obtained by the observer 32. s ^(vector) and the current i of the complete equipment 40 including the influence of the axial velocity d|z| / dt s The difference between the vectors is the current error Δi s The estimated axial velocity d|z^| / dt is obtained by using the relationship between (vector) and the axial velocity d|z| / dt. The calculation of the estimated axial velocity d|z^| / dt is described in detail below. The state equation and output equation of the plant 40 are respectively expressed as the following equations (7) and (8).

[0071] [Formula 6]

[0072]

[0073] [Formula 7]

[0074]

[0075] Here, in Figure 2 In the equation (7) and (8), the matrices in the equation (9), (10), and (11) are determined as A' (matrix), B (matrix), and C (matrix).

[0076] [Formula 8]

[0077]

[0078] [Formula 9]

[0079]

[0080] [Formula 10]

[0081]

[0082] In addition, variables used in equations (7) to (11) are as follows.

[0083] Φ s (vector) = [Φ ds Φ qs ] T : Armature reaction flux

[0084] Φ r (vector) = [Φ dr Φ qr ] T : Rotor flux

[0085] R: stator resistance

[0086] L: Inductance

[0087] v s (vector) = [v d v q ] T : Input voltage to the complete equipment 40

[0088] i s (vector) = [i d i q ] T : Current output from the complete set 40

[0089] ω1: power supply angular frequency

[0090] ω r : Rotational angular velocity of the rotor 20 (electrical angle)

[0091] Among them, the inductance L is the d-axis inductance L d and q-axis inductance L q Let them be equal and represented by L. When distinguishing between the two, let L in the first row and first column of A' (matrix) in formula (9) be Ld , set L in row 2, column 2 to L q In addition, the rotor 20 is displaced in the axial direction, so it is considered that the rotor magnetic flux Φ r (vector) changes, k refers to the rotor flux Φ r (Vector) The inverse of the ratio of change relative to axial displacement.

[0092] The state equation and output equation of the observer 32 are set to the following equations (12) and (13), respectively. In equation (12), it is assumed that the rotational angular velocity ω of the rotor 20 cannot be determined. r When performing detection, the estimated rotation angular velocity ω is used r ^Mark.

[0093] [Formula 11]

[0094]

[0095] [Formula 12]

[0096]

[0097] Here, in Figure 2 In the equation (12) and (13), the matrices in the equation (14) and (15) are determined as A^(matrix) and H(matrix).

[0098] [Formula 13]

[0099]

[0100] [Formula 14]

[0101]

[0102] In addition, the rotation angular velocity ω r When performing detection, the detected rotational angular velocity ω can be used r The rotational angular velocity ω of the rotor 20 is used in the 1st row and 4th column, the 2nd row and 3rd column, the 3rd row and 4th column, and the 4th row and 3rd column of A^ (matrix) in equation (14). r A (matrix) is expressed as shown in the following formula (16).

[0103] [Formula 15]

[0104]

[0105] In addition, the variables used in equations (12) and (13) are as follows: In addition, H (matrix) represented by equation (15) represents the feedback gain.

[0106] Φ s^(vector)=[Φ ds ^Φ qs ^] T : Estimated armature reaction flux

[0107] Φ r ^(vector)=[Φ dr ^Φ qr ^] T : Estimated rotor flux

[0108] i s ^(vector)=[i d ^i q ^] T : Estimated current

[0109] Δi s (vector) = i s ^(vector)-i s (Vector)

[0110] =[Δi d Δi q ] T

[0111] =[i d ^-i d i q ^-i q ] T : Current error

[0112] In equations (14) and (16), the 1st row and 3rd column, the 2nd row and 4th column, the 3rd row and 3rd column, and the 4th row and 4th column of A^ (matrix) are set to 0. This is because, unlike the plant 40, the observer 32 estimates that the rotor 20 of the bearingless motor 1 does not move in the axial direction.

[0113] Here, if the above formula is transformed and rearranged, the current error Δi s (vector) becomes the following equation (17).

[0114] [Formula 16]

[0115]

[0116] Here, s refers to the time differential d / dt, and the superscript “-1” refers to the inverse matrix. In equation (17), instead of using A^ (matrix) and A' (matrix), A (matrix) and the rotation angular velocity error Δω are used. r And the estimated axial velocity d|z| / dt. In addition, the matrix and variables used in equation (17) are as follows.

[0117] I4 (matrix): 4-row 4-column identity matrix

[0118] I (matrix): 2-row, 2-column identity matrix

[0119] [Formula 17]

[0120]

[0121] Δω r =ω r ^-ω r : Rotational angular velocity error

[0122] [Formula 18]

[0123]

[0124] When the d-axis of the controlled dq-axis is substantially aligned with the direction of the N-pole of the permanent magnet 22 of the rotor 20, the rotor magnetic flux Φ in the q-axis direction qr and the estimated rotor flux Φ in the q-axis direction qr The value of ^ can be approximated to 0. In this case, as shown in the following equation (18), equation (17) can be simplified.

[0125] [Formula 19]

[0126]

[0127] As a result, the axial velocity d|z| / dt can be estimated as Δi d / Φ dr Or Δi q / Φ dr The estimated result can be output as the estimated axial velocity d|z ^| / dt by using the function of (18). That is, the velocity estimator 33 can calculate and output the estimated axial velocity d|z ^| / dt using the equation (18).

[0128] In addition, the current error Δi s (vector) is the estimated rotor magnetic flux Φ in the d-axis direction dr The rotor magnetic flux Φ in the ^ and d-axis directions dr Here, the rotor flux Φ in the d-axis direction can be expressed as dr The estimated rotor flux Φ in the d-axis direction dr Alternatively, the rotor flux Φ can be calculated in advance. r The rotor magnetic flux constant, which is a representative constant of the vector, is used instead, and the estimated rotor magnetic flux Φ in the d-axis direction that changes during operation is not used. dr ^.

[0129] As mentioned above, the left side of equation (17) or equation (18), i.e., the current error Δi s(vector) contains the information of the axial velocity d|z| / dt on the right, and the relationship between the two can be clearly understood. s (Vector) It becomes easy to design the coefficient of the gain for estimating the axial velocity d|z| / dt.

[0130] In addition, when estimating the estimated axial velocity d|z ^| / dt, the estimated axial velocity d|z ^| / dt is not set as a state variable, but the current error Δi s (vector) is estimated by the velocity estimator 33. Therefore, the size of the matrix of the plant 40 and the observer 32 does not increase. That is, the state variables can be kept constant at 4, and A (matrix) can be kept constant at 4×4. That is, the amount of calculation in the observer 32 does not increase. As described above, the estimated axial velocity d|z^| / dt is estimated by the velocity estimator 33, thereby reducing the calculation load and facilitating adjustment.

[0131] The control method for controlling the bearingless motor 1 having the rotor 20 and the stator 10 having the motor winding 12 generating torque includes an observation step and a speed estimation step. In the observation step, the observer 32 detects the current value i of the motor winding 12 based on the current value i d 、i q With the current command value i d * 、i q * The voltage command value v is output in a consistent manner d * 、v q * , or the detected value of the voltage applied to the motor winding 12, that is, the voltage detection value v d 、v q , the estimated value of the current flowing in the bearingless motor 1, that is, the estimated current i s ^ (vector) and the estimated value of the rotor magnetic flux generated in the motor winding 12 by the rotor 10, that is, the estimated rotor magnetic flux Φ r In the speed estimation step, the speed estimator 33 estimates the current i s ^(vector) and current detection value i s The difference between the vectors is the current error Δi s (vector), and estimated rotor flux Φ r The estimated axial velocity d|z^| / dt, which is an estimated value of the axial velocity of the rotor 20, is estimated and outputted using at least one of ^ (vector).

[0132] In addition, when not using the voltage detection value vd 、v q In the case of the bearingless motor 1, the control method includes a current detection step and a voltage command value output step. In the current detection step, the current detector of the bearingless motor 1 detects the current of the motor winding 12. In the voltage command value output step, the current controller 31 outputs the current detected in the motor winding 12, i.e., the current detection value i. d 、i q With the current command value i d * 、i q * Output voltage command value v in a consistent manner d * 、v q * Moreover, the output voltage command value v d * 、v q * Even when the voltage detection value is used, the current detection step and the voltage command value output step may be included.

[0133] Next, a configuration example of the speed estimator 33 will be described. The estimated current i input to the speed estimator 33 is s ^(vector) and current detection value i s The vector is obtained by transforming the d-q axis coordinates into a rotating two-axis coordinate. The speed estimator 33 calculates the d-axis current error Δi d The value obtained by multiplying the q-axis current error Δi by the predetermined first coefficient q At least one of the values ​​obtained by multiplying the predetermined second coefficient is output as the estimated axial velocity d|z^| / dt.

[0134] Figures 3 to 7 FIG. 1 is a block diagram showing an example of the structure of a velocity estimator that takes a current error as input and outputs an estimated axial velocity. Figure 3 , shows the use of only the current error Δi s (vector) = [Δi d Δi q ] T The d-axis current error Δi d The speed estimator 33 in this case includes a calculation unit 331a and a P (Proportional) controller 332a. That is, the calculation unit 331a calculates the speed of the d-axis current error Δi d Divide by the estimated rotor flux Φ in the d-axis direction dr ^, the P controller 332a multiplies the calculation result in the calculation unit 331a by the P gain K as the first coefficientP1 , output the estimated axial velocity d|z^| / dt.

[0135] exist Figure 4 The current error Δi is shown in s (vector) = [Δi d Δi q ] T The q-axis current error Δi q The speed estimator 33 in this case includes a calculation unit 331b and a P controller 332b. That is, the calculation unit 331b calculates the q-axis current error Δi q Divide by the estimated rotor flux Φ in the d-axis direction dr ^, the P controller 332b multiplies the calculation result in the calculation unit 331b by the P gain K as the second coefficient P2 , output the estimated axial velocity d|z^| / dt.

[0136] exist Figure 5 The current error Δi is shown in s (vector) = [Δi d Δi q ] T The speed estimator 33 in this case includes a calculation unit 331c and a P controller 332c. That is, the calculation unit 331c calculates the current error Δi s (vector) divided by the estimated rotor magnetic flux Φ in the d-axis direction dr ^, the P controller 332c calculates the calculation result in the calculation unit 331c and the P gain matrix [K P1 K P2 ] is calculated to output the estimated axial velocity d|z^| / dt. In addition, the inner product of the calculation result and the P gain matrix is ​​calculated according to the following formula (19).

[0137] The inner product of the operation result and the P gain matrix = K P1 *(Δi d / Φ dr ^)+K P2 *(Δi q / Φ dr ^)···(19)

[0138] also, Figure 3 and Figure 4 It is equal to P gain matrix [K P1 K P2 ] is set to 0. That is, Figure 3 and Figure 4 The speed estimator 33 shown is Figure 5 In the specific case of the speed estimator 33, Figure 5 The speed estimator 33 shown comprises Figure 3 and Figure 4 The speed estimator 33 is used.

[0139] Figure 6 The speed estimator 33 shown is relative to Figure 5 The speed estimator 33 also has a high-pass filter that removes only DC and low-frequency components. Figure 6 , the case where the high-pass filter is a DC (Direct Current) cutoff HPF (High-Pass Filter) 333 is shown. The current error Δi s The important frequency component of the (vector) is the axial vibration frequency component of the rotor 20, and the DC component is unnecessary. s If there is a DC component in (vector), the DC component will also remain in the estimated axial velocity d|z^| / dt. Therefore, the DC cutoff HPF 333 removes the DC component. In one example, in order to remove the DC component, the DC cutoff HPF 333 with a cutoff frequency of 1 Hz is used.

[0140] exist Figure 7 The current error Δi is shown in s (vector) as input, but not divided by the estimated rotor flux Φ in the d-axis direction dr The speed estimator 33 in this case includes a P controller 332d. The P controller 332d controls the input current error Δi s (vector) and P gain matrix [K P1 K P2 ] is calculated by the inner product of the axial velocity d|z^| / dt. In this case, the estimated rotor magnetic flux Φ in the d-axis direction is equivalent to dr The division operation of ^ is pre-applied to the P gain matrix [K P1 K P2 ]. As a result, it is possible to avoid division operations during operation, reduce the calculation load, and avoid the output becoming unstable due to division by a value close to 0.

[0141] As described above, in order to calculate the estimated axial velocity d|z^| / dt, the current error Δi sThe operation of multiplying (vector) by a coefficient is the P controller 332a-332d. Usually, in order to perform a differential operation to estimate the speed based on the displacement information, a D (Derivative) controller is required. However, if a differential operation is performed, high frequencies will be amplified, so there is a problem that noise including frequencies higher than the frequency components of the required signal will be amplified. However, in embodiment 1, P controllers 332a-332d are used instead of D controllers, so it is possible to suppress the situation where noise including frequencies higher than the frequency components of the required signal is amplified.

[0142] also, Figures 3 to 7 The speed estimator 33 shown is equivalent to taking the coordinate center of the axial position of the rotor 20, i.e., z=0, as the center position magnetically relative to the stator 10, and performing time differentiation on the absolute value of the axial position, and outputting an estimated axial speed d│z^│ / dt. According to the above-mentioned structure, after determining whether the rotor 20 is moving away from or approaching the axis center, the speed can be estimated. If a displacement sensor is used to detect the position of the rotor 20, a signal equivalent to z=0 is obtained in advance, and subsequent processing must be performed to change the sign with this value as a boundary. However, the speed estimator 33 used in the control device 30 of the bearingless motor 1 of embodiment 1 can directly obtain the estimated axial speed d│z^│ / dt without subsequent processing. Therefore, there is no need to adjust the signal equivalent to z=0 in advance.

[0143] As described above, the control device 30 of the bearingless motor 1 according to the first embodiment controls the bearingless motor 1 including the rotor 20 and the stator 10 including the motor winding 12 generating torque. The control device 30 of the bearingless motor 1 includes an observer 32 and a speed estimator 33. The observer 32 uses the current detection value i of the motor winding 12 as the basis for the speed estimation. s (vector) and current command value i d * 、i q * The voltage command value v is output in a consistent manner s * (vector) or the detected value of the voltage applied to the motor winding 12, that is, the voltage detected value, the estimated current i of the bearingless motor 1 s ^(vector) and estimated rotor flux Φ r The speed estimator 33 calculates at least one of the estimated current i s * (vector) and current detection value i s The difference between the vectors is the current error Δi s(vector) and estimated rotor flux Φ r The estimated axial velocity d|z^| / dt of the rotor 20 is calculated by taking at least one of the vectors ^ as an input. The axial position of the rotor 20 can be obtained using the estimated axial velocity d|z^| / dt, and a sensor for detecting the axial displacement, velocity or acceleration of the rotor 20 is not required. That is, compared with the conventional bearingless motor having a sensor for detecting the axial displacement, velocity or acceleration of the rotor 20, the following effect is achieved, that is, the axial displacement, velocity or acceleration of the rotor 20 can be estimated while simplifying the structure.

[0144] Implementation method 2.

[0145] In the first embodiment, the armature reaction flux Φ is used as the state variable. s (vector) or current i s (vector) and rotor flux Φ r (Vector) Both. However, the state variables can also be reduced. In the second embodiment, the control device 30 of the bearingless motor 1 that can calculate the estimated axial velocity d|z^| / dt by reducing the state variables will be described.

[0146] Figure 8 1 is a block diagram showing an example of the structure of the control device for the bearingless motor according to the second embodiment. Here, when the state variable is only the current, the bearingless motor 1 is taken as the control object, that is, the plant 40, and the voltage v is taken as s (vector) as input to the observer 32A, and the current error Δi s (vector) A velocity estimator 33 outputs an estimated axial velocity d|z^| / dt as input.

[0147] The control device 30A of the bearingless motor 1 according to the second embodiment includes a current controller 31, an observer 32A, and a speed estimator 33. The second embodiment is different from the first embodiment in that the observer 32A uses the state variable as the current i s (vector), for the estimated current i s ^(vector)=[i d ^i q ^] T The same components as those in Embodiment 1 are denoted by the same reference numerals, and their description is omitted.

[0148] The following describes a method for calculating the estimated axial velocity d|z^| / dt using the current error Δis (vector) as input. s (vector) = [i d iq ] T The state equation and output equation of the complete set of equipment 40 at this time are shown in the following equations (20) and (21) respectively.

[0149] [Formula 20]

[0150]

[0151] [Formula 21]

[0152]

[0153] Here, Δθ is the deviation of the estimated rotation angle θ^ from the rotation angle θ, that is, the rotation angle error, which is expressed by θ^-θ, Φ m is the rotor magnetic constant.

[0154] When the rotation angle error Δθ is close to 0, if it can be approximated as cosΔθ≒1 and sinΔθ≒Δθ, the state equation of formula (20) can also be expressed as the following formula (22).

[0155] [Formula 22]

[0156]

[0157] On the other hand, the state equation and output equation of the observer 32A are set to the following equations (23) and (24).

[0158] [Formula 23]

[0159]

[0160] [Formula 24]

[0161]

[0162] Here, in Figure 8 In the formula (22) and (23), the matrices in the formula (25) to (28) are defined as H2 (matrix), A2 (matrix), E' (matrix), and E^ (matrix). In addition, H2 (matrix) is a matrix representing feedback gain.

[0163] [Formula 25]

[0164]

[0165] [Formula 26]

[0166]

[0167] [Formula 27]

[0168]

[0169] [Formula 28]

[0170]

[0171] Here, if the above formula is transformed and rearranged, the current error Δi s (vector) becomes the following equation (29).

[0172] [Formula 29]

[0173]

[0174] Here, the following property is used: when Δθ, |z| / k, and (1 / k)*d|z| / dt are values ​​close to 0, Δθ*|z| / k and Δθ*(1 / k)*d|z| / dt are very small and can be ignored compared with other terms.

[0175] The current error Δi on the left side of equation (29) s (Vector) contains a component related to the first term d|z| / dt on the right side and a component related to the rotation angle error Δθ in the second term. Therefore, it is possible to calculate the current error Δi s (Vector) The estimated axial velocity d|z^| / dt and the estimated rotation angle θ^ are estimated.

[0176] In the second embodiment, the state variable representing the state of the plant 40 is set to be only the current i observed in the motor winding 12 of the stator 10. s (vector), that is, as the d-axis current i d and q-axis current i q , forming a current error Δi s The relationship between (vector) and the axial velocity d|z| / dt and the rotation angle θ. And, based on this relationship, the estimated axial velocity d|z^| / dt and the estimated rotation angle θ^ are calculated. As described above, by setting the state variables to two, there is the following effect, that is, the amount of calculation can be reduced compared to the case where the state variables are four.

[0177] Implementation method 3.

[0178] In the third embodiment, the control device 30, 30A of the bearingless motor 1 further has a function of generating a d-axis current command value i d * The d-axis current command value generator generates the d-axis current command value i using the estimated axial velocity d|z^| / dt output from the velocity estimator 33. d * , output to the current controller 31.

[0179] Fig. 9 1 is a block diagram showing an example of the structure of a d-axis current command value generator in the bearingless motor control device according to Embodiment 3. The d-axis current command value generator 35 receives the estimated axial velocity d|z^| / dt from the velocity estimator 33 as input and outputs a d-axis current command value i d * The d-axis current command value generator 35 includes an axial position controller 351, a zero value output device 352, and a switch 353. The axial position controller 351 outputs a d-axis current command value i according to the estimated axial velocity d|z^| / dt. d * The 0 value output device 352 takes the d-axis current command value i d * The switch 353 selects one of the output of the axial position controller 351 and the output from the zero value output device 352 as the d-axis current command value i d * The 0 value output device 352 sometimes outputs the d-axis current command value i d * Used when set to 0. Fig. 9 In the example, the estimated axial velocity d|z^| / dt is input and the axial position controller 351 outputs the d-axis current command value i d * , the d-axis current can be adjusted.

[0180] The d-axis current command value generator 35 can specify a positive d-axis current when the estimated axial velocity d|z^| / dt is positive, and specify a negative d-axis current when it is negative. A typical controller that outputs the above-described command is a P controller. Fig.10 1 is a block diagram showing an example of the structure of a d-axis current command value generator in the bearingless motor control device according to the third embodiment. Fig.10 , the case where the P controller 351a is used in the axial position controller 351 is shown. The P gain of the P controller 351a is set to K P5 By adding K P5 Set to a positive value to make the signs of the input and output consistent.

[0181] In addition, the axial position controller 351 is not limited to the P controller 351a that makes the output proportional to the input. It is also possible to use a function that outputs 1 if the input value is positive and -1 if the input value is negative, that is, a sgn (signum) function. It is also possible to use the sgn function in combination with the P controller 351a. In addition, a limiter may be set for the input value. In addition, the value of the cube of the input may also be used.

[0182] The P controller 351a is used in the axial position controller 351, and the d-axis current i d is the K for estimating the axial velocity d|z^| / dt P5 times, and the condition that the axial velocity d|z^| / dt is equal to the axial velocity d|z| / dt is satisfied. At this time, the axial motion equation becomes the following equation (30).

[0183] [Formula 30]

[0184]

[0185] Here, when z ≥ 0, the following equation (31) is obtained, k zi K p5 z>0 holds. In addition, when z<0, the following equation (32) is obtained, k zi K p5 (-z)>0 holds.

[0186] [Formula 31]

[0187]

[0188] [Formula 32]

[0189]

[0190] As described above, it is proportional to the axial velocity d|z| / dt, and a force can be generated in the direction opposite to the velocity. This is equivalent to a damping force that attenuates vibration. That is, the d-axis current command value i is generated based on the estimated axial velocity d|z^| / dt output from the velocity estimator 33. d * Therefore, when the rotor 20 vibrates in the axial direction, a damping force can be generated to attenuate the vibration.

[0191] In the third embodiment, the control method of the bearingless motor 1 includes taking the estimated axial velocity d|z^| / dt as input and outputting the d-axis current command value i d * The d-axis current command value generator 35 specifies a positive d-axis current command value i if the estimated axial velocity d|z^| / dt becomes positive. d *If it becomes a negative value, a negative d-axis current command value i is specified. d * The d-axis current command value generator 35 is configured to generate the d-axis current command value of the motor winding 12. d The force increases or decreases in accordance with the axial vibration of the rotor 20. As a result, an axial attraction force can be generated between the stator 10 and the rotor 20 in such a way that the axial vibration of the rotor 20 is attenuated. In addition, in this control, there is no need to add a thrust magnetic bearing or other device, so the structure is compact and the cost is not increased, and the stability of the original passive stability direction of the two-axis control type bearingless motor 1, that is, the axial direction, can be improved.

[0192] Implementation method 4.

[0193] Fig.11 1 is a block diagram showing an example of the configuration of a speed estimator of a bearingless motor control device according to the fourth embodiment. In the fourth embodiment, the speed estimator 33 calculates the current error Δi s (vector) as input, output estimated axial velocity d|z^| / dt and estimated rotational angular velocity ω r The current error Δi described in the first embodiment is s In the equation (17) of (vector), the first term on the right side represents the rotation angular velocity error Δω r , the second term on the right represents the axial velocity d|z| / dt. That is, the current error Δi s (vector) has a rotational angular velocity error Δω r and axial speed d|z| / dt. Therefore, according to the current error Δi s (vector), not only the axial velocity d|z| / dt can be estimated, but also the rotational angular velocity ω r .

[0194] Fig.12 1 is a block diagram showing an example of the structure of a control device for a bearingless motor according to Embodiment 4. Figure 2 The same structural elements as those described in the above are denoted by the same reference numerals and their description is omitted. Fig.12 In the control device 30B of the bearingless motor 1, the estimated rotation angular velocity ω estimated by the speed estimator 33 is used in the observer 32. r That is, the observer 32 does not use the signal of the rotation angular velocity sensor, but uses the estimated rotation angular velocity ω output from the velocity estimator 33. r The value of ^ replaces the rotation angular velocity ω r .

[0195] Next, a configuration example of the speed estimator 33 used in the fourth embodiment will be described. Fig.13 1 is a block diagram showing an example of the configuration of a speed estimator used in the control device for a bearingless motor according to Embodiment 4. The speed estimator 33 includes a calculation unit 331c, a P controller 332c, and a PI controller 334. That is, the calculation unit 331c calculates the current error Δi s (vector) divided by the estimated rotor magnetic flux Φ in the d-axis direction dr The calculation unit 331c outputs the result of the division to the P controller 332c and the PI controller 334. The processing in the P controller 332c is the same as that in the first embodiment. Figure 5 The description is the same and therefore will be omitted.

[0196] The PI controller 334 calculates the calculation result in the calculation unit 331c and the PI gain matrix [K P3 +K I3 / s K P4 +K I4 / s] is calculated by the inner product and the estimated rotation angular velocity ω is output r ^. The PI controller 334 also performs an integral operation. The K of the PI gain matrix I3 / s etc. is equivalent to an integral operation. That is, 1 / s of the term represents an integral operation, K I3 , K I4 represents the integral gain. In addition, the PI controller 334 amplifies the DC component and feeds it back. s When the DC component of (vector) is not 0, the rotation angular velocity ω is estimated r ^ changes, and the rotation angular velocity ω is estimated r ^ Approximate rotational angular velocity ω r At the same time, the current error Δi s The DC component of (vector) is close to 0, which is a stable state. Therefore, the estimated rotation angular velocity ω can be r ^ and the angular velocity ω r Consistent.

[0197] In order to make the rotation angular velocity error Δω r Convergence, current error Δi s Δω contained in (vector) r The DC and low-frequency components are important. In addition, in order to make the axial speed d|z| / dt converge, the current error Δi s The intermediate frequency component to the high frequency component of the axial direction close to the natural angular vibration frequency corresponding to the change of the axial velocity d|z| / dt contained in the (vector) is important. s The DC component of the vector is amplified to extract the rotational angular velocity ωr The information of the axial velocity d|z| / dt can be extracted by not amplifying the DC component. r The axial speed d|z| / dt is separated and fed back.

[0198] Fig.14 1 is a block diagram showing an example of the structure of a speed estimator used in the control device for the bearingless motor according to the fourth embodiment. Fig.13 The same components are denoted by the same reference numerals, and their description is omitted. Fig.14 The speed estimator 33 shown is Fig.13 The P controller 332c has a high-pass filter, namely, a DC cutoff HPF 333, which removes only DC and low-frequency components. As described above, by adding the DC cutoff HPF 333 to the detection module of the estimated axial velocity d|z^| / dt, the DC component can be removed from the estimated axial velocity d|z^| / dt, and the rotational angular velocity ω can be obtained. r The axial velocity d|z| / dt is separated and estimated with high accuracy.

[0199] In the fourth embodiment, the speed estimator 33 estimates the current error Δi s (vector) and outputs the estimated axial velocity d|z^| / dt and the estimated rotational angular velocity ω r That is, according to the current error Δi s (vector), it is not only possible to estimate the estimated axial speed d|z^| / dt of the rotor 20, but also possible to estimate the angle of the rotor 20 at the same time. By estimating the angle of the rotor 20 based on the current, the rotation control and floating control of the bearingless motor 1 can be implemented without using the signal of the angle sensor. As a result, it is possible to solve the problem that the noise of the angle sensor generated during the operation of the bearingless motor 1 with an angle sensor affects the control. In addition, it is used for noise countermeasures, and it is possible to avoid the phase delay of the angle sensor signal using the LPF (Low-Pass Filter) to remove the high-frequency component, the change in the characteristics of the angle sensor caused by temperature changes, etc., and it is possible to avoid problems such as the breakage of the signal line in the detection signal from the angle sensor. In addition, from the current error Δi s The DC component of this same input (vector) is amplified to estimate the estimated rotation angular velocity ω r ^, without amplifying the DC component, the estimated axial velocity d|z^| / dt can be estimated. r ^ and the estimated axial velocity d|z^| / dt are simultaneously separated and fed back.

[0200] Implementation method 5.

[0201] In the first embodiment, the armature reaction flux Φ is used as the state variable. s (vector) or current i s (vector) and rotor flux Φ r However, it is also possible to use the state variable as only the rotor flux Φ r (vector). In the fifth embodiment, the state variables are reduced to only the rotor magnetic flux Φ. r (vector), a control device 30 for the bearingless motor 1 that can calculate an estimated axial velocity d|z^| / dt.

[0202] Fig.15 1 is a block diagram showing an example of the structure of the control device for the bearingless motor according to the fifth embodiment. r (vector), the bearingless motor 1 is taken as the control object, that is, the plant 40, which has the voltage v s (vector) as input, and a speed estimator 33 which takes the rotor flux error as input and outputs an estimated axial speed d|z^| / dt. Fig.15 In the control device 30C for the bearingless motor 1 of the present invention, the same components as those in the first embodiment are denoted by the same reference numerals.

[0203] The calculation method of the estimated axial velocity d|z^| / dt is described below. Assuming that the state variable is only the rotor magnetic flux Φ r The state equations of the plant 40 when (vector) are shown in the following equations (33) and (34).

[0204] [Formula 33]

[0205]

[0206] [Formula 34]

[0207]

[0208] Next, the observer 32 is constructed as shown in the following equation (35).

[0209] [Formula 35]

[0210]

[0211] Here, in Fig.15 In the equation (35), the matrix expressions in equation (36) and (37) are determined as A2' (matrix) and F (matrix).

[0212] [Formula 36]

[0213]

[0214] [Formula 37]

[0215]

[0216] The right side of equation (35) does not include the rotor flux Φ which is difficult to measure directly. r (vector), are all known values ​​or values ​​calculated during operation. Therefore, by using this formula, it is possible to estimate the rotor flux [Φ dr ^Φ qr ^] T Here, if the right side related to F (matrix) of equation (37) is transformed, the following equation (38) is obtained.

[0217] [Formula 38]

[0218]

[0219] If it is set to Φ qr ≒0,Φ qr ^≒0 and Φ dr ≒Φ dr ^, then equation (38) becomes equation (39).

[0220] [Formula 39]

[0221]

[0222] Therefore, it is possible to construct an observer 32 that is constructed so as to be able to dr ^Φ qr ^] T After calculation, the estimated rotor flux [Φ dr ^Φ qr ^] T The velocity estimator 33 takes the function F (matrix) shown in equation (37) as input. If F (matrix) is taken as input, the value of the estimated axial velocity d|z ^| / dt or the rotational angular velocity error Δω can be estimated. r =ω r ^-ω r The value of .

[0223] In the fifth embodiment, the state variable indicating the state of the plant 40 is set to only the rotor magnetic flux Φ r (vector), will contain the axial velocity d|z| / dt and the rotational angular velocity error Δω rThe function including is input to the velocity estimator 33. Thus, as in the case of the second embodiment, the number of state variables is two, and thus the amount of calculation can be reduced compared to the case of four state variables. In addition, the differential calculation for estimating the estimated axial velocity d|z^| / dt can be eliminated.

[0224] Implementation method 6.

[0225] In the first to fifth embodiments, the control device 30 of the bearingless motor 1 is provided with the speed estimator 33. The speed estimator 33 estimates the current i s ^(vector) and current detection value i s The difference between the vectors is the current error Δi s (vector) and estimated rotor flux Φ r The estimated axial speed of the rotor 20 is calculated and outputted by taking at least one of the vectors d|z^| / dt as an input. However, the estimated axial speed d|z^| / dt may be calculated based on the current error Δi instead of being an intermediate variable. s (vector) and estimated rotor flux Φ r d-axis current command value i d * Perform calculations.

[0226] Fig.16 1 is a block diagram showing an example of the structure of a control device for a bearingless motor according to Embodiment 6. Figure 2 The same structural elements as those described in the above are denoted by the same reference numerals and their description is omitted. Fig.16 The control device 30D of the bearingless motor 1 includes an axial position controller 36 instead of the speed estimator 33. The axial position controller 36 determines the current error Δi s (vector) and estimated rotor flux Φ r The d-axis current command value i for controlling the axial position of the rotor 20 is obtained by using at least one of the vectors ^ and the value calculated by the observer 32. d * The axial position controller 36 calculates and outputs the calculated d-axis current command value i d * The current value deviation calculation unit 34d is outputted.

[0227] In addition, Fig.16, a case is shown in which the control device 30 of the bearingless motor 1 in embodiment 1 replaces the speed estimator 33 with an axial position controller 36, but the control devices 30A, 30B, and 30C of the bearingless motor 1 in embodiments 2 to 5 may also replace the speed estimator 33 with an axial position controller 36.

[0228] The control device 30 of the bearingless motor 1 according to the sixth embodiment has a control method based on the current error Δi s (vector) and estimated rotor flux Φ r At least one of the vectors ^(vector) has an influence on the d-axis current command value i d * The axial position controller 36 performs calculations and outputs the d-axis current command value i corresponding to the axial displacement, speed or acceleration of the rotor 20 can be directly controlled. d * Perform calculations.

[0229] Fig.17 This is a diagram showing an example of a hardware configuration for realizing a control device for a bearingless motor according to the first to sixth embodiments. Fig.17 This is a structural example in which the main parts of the control device 30, 30A, 30B, 30C, 30D of the bearingless motor 1, namely the current controller 31, the observer 32, 32A, the speed estimator 33, the axial position controller 36 and the d-axis current command value generator 35, are implemented by a processing circuit 61 having a processor 63 and a memory 64.

[0230] The processor 63 is a CPU (Central Processing Unit). The processor 63 executes a control program. The control program is a program that describes processing for causing the processing circuit 61 to operate as the main parts of the control device 30, 30A, 30B, 30C, 30D of the bearingless motor 1, namely, the current controller 31, the observer 32, 32A, the speed estimator 33, the axial position controller 36, and the d-axis current command value generator 35.

[0231] In one example, the memory 64 is a nonvolatile or volatile memory such as RAM (Random Access Memory), ROM (Read Only Memory), flash memory, EPROM (Erasable Programmable ROM), EEPROM (registered trademark) (Electrically Erasable Programmable ROM). The memory 64 stores the control program. The memory 64 is also used as a temporary memory when the processor 63 executes various processes.

[0232] The input unit 62 is a circuit for receiving input signals to the control devices 30, 30A, 30B, 30C, 30D from the outside. The output unit 65 is a circuit for outputting signals generated by the control devices 30, 30A, 30B, 30C, 30D to the outside of the control devices 30, 30A, 30B, 30C, 30D.

[0233] The functions of the processing circuit 61 can be realized by a processing circuit as dedicated hardware. The processing circuit as dedicated hardware is, for example, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a circuit formed by combining them. A part of the main parts of the control device 30, 30A, 30B, 30C, 30D of the bearingless motor 1 is realized by the processor 63 and the memory 64, and the remaining part is realized by dedicated hardware.

[0234] The configuration described in the above embodiment is merely an example, and may be combined with other known technologies, the embodiments may be combined with each other, and part of the configuration may be omitted or changed without departing from the gist.

[0235] Description of the label

[0236] 1 bearingless motor, 10 stator, 11 stator core, 12 motor winding, 13 supporting winding, 20 rotor, 21 shaft, 22 permanent magnet, 30, 30A, 30B, 30C, 30D control device, 31 current controller, 32, 32A observer, 33 speed estimator, 34d, 34q current value deviation calculation unit, 35d axis current command value generator, 36, 351 axial position controller, 40 complete set of equipment, 41 axial motion model, 61 processing circuit, 62 input unit, 63 processor, 64 memory, 65 output unit, 331a, 331b, 331c calculation unit, 332a, 332b, 332c, 332d, 351a P controller, 333 DC cut-off HPF, 334 PI controller, 352 0 value output device, 353 switch.

Claims

1. A bearingless motor control device for controlling a bearingless motor having a rotor and a stator having a motor winding for generating torque, wherein the rotor and the stator are arranged with a predetermined gap therebetween. The control device for the bearingless motor is characterized by comprising: an observer that calculates at least one of an estimated current that is an estimated value of current flowing in the bearingless motor and an estimated rotor magnetic flux that is an estimated value of rotor magnetic flux generated in the motor winding by the rotor, based on a voltage command value of the motor winding or a voltage detection value that is a detection value of voltage applied to the motor winding; and A speed estimator calculates and outputs an estimated axial speed of the rotor, i.e., an estimated value of the axial speed of the rotor, by taking as input at least one of a current error, i.e., a difference between the estimated current and a current detection value of the motor winding current, and the estimated rotor magnetic flux.

2. The control device for a bearingless motor according to claim 1, characterized in that: The estimated current and the current detection value are obtained by transforming into a rotating two-axis coordinate system, namely, a d-q axis. The speed estimator outputs the estimated axial speed based on at least one of a value obtained by multiplying the d-axis current error by a predetermined first coefficient and a value obtained by multiplying the q-axis current error by a predetermined second coefficient.

3. The control device for a bearingless motor according to claim 1, characterized in that: The speed estimator uses the coordinate center of the axial position of the rotor as the center position magnetically relative to the stator, and outputs the estimated axial speed corresponding to a value obtained by time-differentiating an absolute value of the axial position.

4. The control device for a bearingless motor according to claim 2, characterized in that: The device further includes a current command value generator that receives the estimated axial velocity as an input and outputs a command value of the current of the d-axis.

5. The control device for a bearingless motor according to claim 4, characterized in that: The current command value generator outputs a positive command value of the d-axis current when the estimated axial velocity is a positive value, and outputs a negative command value of the d-axis current when the estimated axial velocity is a negative value.

6. The control device for a bearingless motor according to claim 1 or 2, characterized in that: The observer estimates that the rotor of the bearingless motor does not move in the axial direction. The speed estimator obtains the axial speed based on a relational expression between the current error, which is a difference between the estimated current obtained by the observer and the current of the plant including the influence of the axial speed, and the axial speed.

7. The control device for a bearingless motor according to claim 1, characterized in that: The speed estimator takes at least one of the current error and the estimated rotor flux as input and outputs the estimated axial speed, and simultaneously takes at least one of the current error and the estimated rotor flux as input and outputs an estimated value of the rotor's rotational angular velocity, namely, the estimated rotational angular velocity.

8. A bearingless motor control device for controlling a bearingless motor having a rotor and a stator having a motor winding for generating torque, wherein the rotor and the stator are arranged with a predetermined gap therebetween. The control device for the bearingless motor is characterized by comprising: an observer that calculates at least one of an estimated current that is an estimated value of current flowing in the bearingless motor and an estimated rotor magnetic flux that is an estimated value of rotor magnetic flux generated in the motor winding by the rotor, based on a voltage command value of the motor winding or a voltage detection value that is a detection value of voltage applied to the motor winding; and An axial position controller receives as input at least one of a current error, which is a difference between the estimated current and a current detection value of the motor winding current, and the estimated rotor flux, and outputs a d-axis current command value for controlling the axial position of the rotor.

9. The control device for a bearingless motor according to any one of claims 1 to 8, characterized in that: When the voltage command value is used, the following is also provided: A current detector for detecting the current of the motor winding; as well as A current controller outputs the voltage command value so that the current detection value detected by the current detector coincides with a current command value.

10. A motor system, characterized in that: have: A bearingless motor including a rotor and a stator having a motor winding for generating torque, wherein the rotor and the stator are arranged with a predetermined gap therebetween; and A control device for a bearingless motor, which controls the bearingless motor. The control device of the bearingless motor comprises: an observer that calculates at least one of an estimated current that is an estimated value of current flowing in the bearingless motor and an estimated rotor magnetic flux that is an estimated value of rotor magnetic flux generated in the motor winding by the rotor, based on a voltage command value of the motor winding or a voltage detection value that is a detection value of voltage applied to the motor winding; as well as A speed estimator calculates and outputs an estimated axial speed of the rotor, i.e., an estimated value of the axial speed of the rotor, by taking as input at least one of a current error, i.e., a difference between the estimated current and a current detection value of the motor winding current, and the estimated rotor magnetic flux.

11. A method for controlling a bearingless motor, comprising controlling a bearingless motor having a rotor and a stator having a motor winding for generating torque, wherein the rotor and the stator are arranged with a predetermined gap therebetween. The control method of the bearingless motor is characterized by comprising: an observation step of calculating at least one of an estimated current, which is an estimated value of a current flowing in the bearingless motor, and an estimated rotor flux, which is an estimated value of a rotor flux generated in the motor winding by the rotor, based on a voltage command value of the motor winding or a voltage detection value, which is a detection value of a voltage applied to the motor winding; and The speed estimating step calculates and outputs an estimated axial speed of the rotor, i.e., an estimated value of the axial speed of the rotor, by taking as input at least one of a current error, i.e., a difference between the estimated current and the current detection value of the motor winding, and the estimated rotor magnetic flux.

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