Magnetic pole position estimation device and magnetic pole position estimation method

Abstract

To provide a magnetic pole position estimation device and a magnetic pole position estimation method which can estimate a magnetic pole position of a mover.SOLUTION: A magnetic pole position estimation device includes a voltage command setting part, a first calculation part, and a second calculation part. The voltage command setting part sets a plurality of d-axis voltage commands which are voltage commands in a d-axis direction that is a field direction of a motor so that the voltage command values are different. The first calculation part applies a d-axis voltage which is a voltage in the d-axis direction on the basis of the d-axis voltage command, for each of the d-axis voltage commands set by the voltage command setting part, and calculates a temporal magnetic pole position obtained by vibrating a mover with respect to a stator at predetermined amplitude and frequency, and estimating a magnetic pole position of the mover. The second calculation part calculates an estimated magnetic pole position obtained by estimating the magnetic pole position of the mover, on the basis of a relation between the d-axis voltage command set by the voltage command setting part and the temporal magnetic pole position calculated by the first calculation part.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] This specification discloses techniques relating to a magnetic pole position estimation device and a magnetic pole position estimation method. [Background technology]

[0002] The magnetic pole position detection device described in Patent Document 1 includes a signal selection means, an average value calculation means, and a relative magnetic pole position calculation means. The signal selection means compares the magnitudes of three magnetic detection signals generated by the magnetic detection element unit and shifted in phase by 120 degrees in electrical angle, and assigns an H level signal to the maximum magnetic detection signal and an L level signal to the minimum magnetic detection signal. The average value calculation means calculates the average value of the two magnetic detection signals to which the H level signal and the L level signal are assigned, to generate an average value signal. The relative magnetic pole position calculation means calculates the relative magnetic pole position within a predetermined angular range of electrical angle based on the average value signal.

[0003] The drive device for a synchronous motor described in Patent Document 2 includes a command voltage generating means for generating a three-phase voltage command signal for applying a high-frequency voltage to the synchronous motor, a current detecting means for detecting a current flowing through the synchronous motor when the high-frequency voltage is applied, and a magnetic pole position estimating means for estimating a magnetic pole position of the synchronous motor based on the current detection result. The command voltage generating means generates a three-phase voltage command signal by sequentially switching between a first applied voltage mode, a second applied voltage mode, and a third applied voltage mode. The first applied voltage mode applies a harmonic voltage that alternates between positive and negative to an arbitrary phase with an arbitrary voltage amplitude. The second applied voltage mode applies a high-frequency voltage of the same amplitude to a phase shifted by 120 degrees in electrical angle from the arbitrary phase. The third applied voltage mode applies a high-frequency voltage of the same amplitude to a phase shifted by 240 degrees in electrical angle from the arbitrary phase.

[0004] The current detection means detects the positive and negative values ​​of the pulsating current generated by the application of the high frequency voltage in the first applied voltage mode, the second applied voltage mode, and the third applied voltage mode, one phase at a time in each mode, to detect the current values ​​of each positive and negative phase. The magnetic pole position estimation means calculates an estimated magnetic pole position of the synchronous motor using the detected current values ​​of each positive phase and the detected current values ​​of each negative phase. Specifically, the drive device for the synchronous motor includes an averaging processing means that averages the current values ​​detected at at least one point in each of the first applied voltage mode, the second applied voltage mode, and the third applied voltage mode, for each detection point in each mode.

[0005] The magnetic saturation characteristic calculation unit described in Patent Document 3 includes a magnetic saturation table storage unit and a magnetic saturation function fitting unit. The magnetic saturation table storage unit stores the estimated magnetic flux amount and the final d-axis current value for the number of times calculated by the magnetic flux estimation unit. The magnetic saturation function fitting unit fits the obtained estimated magnetic flux amount and the final d-axis current value with an exponential function using the least squares method or the like. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2001-136776 A [Patent Document 2] JP 2011-050198 A [Patent Document 3] JP 2010-068627 A Summary of the Invention [Problem to be solved by the invention]

[0007] When controlling an electric motor using a position sensor, it is necessary to estimate the magnetic pole position of the mover in order to grasp the positional relationship between the magnetic pole position of the mover and the position sensor.

[0008] In consideration of the above circumstances, this specification discloses a magnetic pole position estimation device and a magnetic pole position estimation method capable of estimating the magnetic pole position of a mover. [Means for solving the problem]

[0009] This specification discloses a magnetic pole position estimation device including a voltage command setting unit, a first calculation unit, and a second calculation unit. The voltage command setting unit sets a plurality of d-axis voltage commands, which are voltage commands in the d-axis direction, which is the field direction of the motor, so that the voltage command values ​​are different. The first calculation unit applies a d-axis voltage, which is a voltage in the d-axis direction, based on the d-axis voltage command for each of the d-axis voltage commands set by the voltage command setting unit, and vibrates a mover with respect to a stator at a predetermined amplitude and frequency to calculate a tentative magnetic pole position by estimating the magnetic pole position of the mover. The second calculation unit calculates an estimated magnetic pole position by estimating the magnetic pole position of the mover based on the relationship between the d-axis voltage command set by the voltage command setting unit and the tentative magnetic pole position calculated by the first calculation unit.

[0010] This specification also discloses a magnetic pole position estimation method including a voltage command setting step, a first calculation step, and a second calculation step. The voltage command setting step sets a plurality of d-axis voltage commands, which are voltage commands in the d-axis direction, which is the field direction of the motor, so that the voltage command values ​​are different. The first calculation step applies a d-axis voltage, which is a voltage in the d-axis direction, based on the d-axis voltage command for each of the d-axis voltage commands set by the voltage command setting step, and vibrates a mover with a predetermined amplitude and frequency relative to a stator to calculate a tentative magnetic pole position by estimating the magnetic pole position of the mover. The second calculation step calculates an estimated magnetic pole position by estimating the magnetic pole position of the mover based on the relationship between the d-axis voltage command set by the voltage command setting step and the tentative magnetic pole position calculated by the first calculation step.

[0011] This specification discloses the technical idea of ​​changing "the magnetic pole position estimation device according to claim 3" to "the magnetic pole position estimation device according to any one of claims 3 to 5" in claim 6 of the claims originally attached to the application (hereinafter referred to as the initial claims). Also, this specification discloses the technical idea of ​​changing "the magnetic pole position estimation device according to claim 1" to "the magnetic pole position estimation device according to any one of claims 1 to 6" in claim 7 of the initial claims. Effect of the Invention

[0012] According to the above magnetic pole position estimation device, a tentative magnetic pole position can be calculated for each of a plurality of d-axis voltage commands, and an estimated magnetic pole position can be calculated based on the relationship between the d-axis voltage command and the tentative magnetic pole position. What has been described above about the magnetic pole position estimation device can also be said about the magnetic pole position estimation method. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a configuration diagram showing an example of an electric motor control system. [Diagram 2] FIG. 2 is a diagram illustrating an example of a configuration of a mover. [Diagram 3] FIG. 2 is a block diagram showing an example of a control block of the control device. [Figure 4] FIG. 2 is a block diagram showing an example of a control block of the magnetic pole position estimation device. [Diagram 5] 4 is a flowchart showing an example of a control procedure performed by the magnetic pole position estimation device. [Figure 6] FIG. 11 is a diagram showing an example of a change over time in a d-axis voltage command. [Figure 7] 11 is a diagram showing an example of a change over time in a position command of a mover. FIG. [Figure 8] 11A and 11B are diagrams illustrating an example of a change over time in a detection result of a position sensor. [Figure 9] FIG. 11 is a diagram showing an example of the relationship between a d-axis voltage command and a provisional magnetic pole position. [Figure 10] FIG. 10 is an enlarged view of a part of FIG. [Figure 11] FIG. 1 is a perspective view showing an example of an ultrasound diagnostic system. [Figure 12] FIG. 12 is a side view of the robot of FIG. [Figure 13] FIG. 4 is a block diagram showing another example of a control block of the control device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] 1. Embodiment 1-1. Configuration example of electric motor control system 10 The magnetic pole position estimation device 70 can be applied to an electric motor control system 10. As shown in Fig. 1, the electric motor control system 10 of the embodiment includes a power supply 20, a smoothing capacitor 30, a power converter 40, and a control device 60. In addition, an electric motor 50 is electrically connected to the power converter 40.

[0015] The power source 20 supplies driving power for the electric motor 50. The power source 20 may take various forms as long as it can supply driving power for the electric motor 50. The power source 20 outputs, for example, DC power. For example, a lead storage battery (battery), a lithium ion battery, a power generation device (for example, a fuel cell), or the like can be used as the power source 20. In addition, the power source 20 can also boost low-voltage DC power using, for example, a known boost converter. The smoothing capacitor 30 smoothes the DC power output from the power source 20. For example, an electrolytic capacitor can be used as the smoothing capacitor 30. The DC power supplied from the power source 20 is smoothed by the smoothing capacitor 30, thereby reducing ripples.

[0016] The power converter 40 converts DC power output from the power source 20 into AC power and outputs the converted AC power to the electric motor 50. As shown in Fig. 1, the power converter 40 includes a plurality of (six) switching elements (three pairs of switching elements 41 in the embodiment), which are full-bridge connected. In each of the three pairs of switching elements 41, a positive-side switching element 4xp connected to the positive side of the power source 20 and a negative-side switching element 4xn connected to the negative side of the power source 20 are connected in series. Note that the electric motor 50 in the embodiment is a three-phase machine, and x is any one of u, v, and w (the same applies below).

[0017] The control device 60 controls the power converter 40 by controlling the opening and closing of a plurality of (six) switching elements (positive-side switching elements 4xp and negative-side switching elements 4xn constituting three pairs of switching elements 41) of the power converter 40. In this way, the power converter 40 converts the DC power output from the power source 20 into AC power. As shown in FIG. 1, an output terminal 42x is provided between the positive-side switching element 4xp and the negative-side switching element 4xn. The output terminal 42x is electrically connected to a phase terminal 43x of the electric motor 50 by a power cable 44x. The power cable 44x supplies the AC power converted by the power converter 40 to the electric motor 50.

[0018] The electric motor 50 includes a stator 51 and a mover 52. The electric motor 50 of the embodiment may be a cylindrical electric motor of a radial air gap type or an axial air gap type in which the stator 51 and the mover 52 are arranged coaxially, or may be a linear electric motor in which the mover 52 moves linearly relative to the stator 51. In either case, the stator 51 includes coils (U-phase coil 51u, V-phase coil 51v, and W-phase coil 51w), and the mover 52 includes a permanent magnet 52b. As shown in FIG. 1, the coils (U-phase coil 51u, V-phase coil 51v, and W-phase coil 51w) can be connected in a Y-connection. In the figure, the neutral point is indicated by a neutral point 51n. The coils (U-phase coil 51u, V-phase coil 51v, and W-phase coil 51w) can also be connected in a Δ-connection.

[0019] As shown in Fig. 2, the mover 52 includes a mover core 52a, a predetermined number of magnetic pole pairs (eight, four magnetic pole pairs in the embodiment), and a shaft 52c. This figure is a schematic diagram of the mover 52 as viewed in the axial direction (perpendicular to the paper surface of the figure), and shows the arrangement of these elements. The mover core 52a is formed into a cylindrical shape by laminating a plurality of thin electromagnetic steel plates (e.g., silicon steel plates) in the axial direction (perpendicular to the paper surface of the figure). The mover core 52a is provided with a shaft 52c, which passes through the axis of the mover core 52a along the axial direction. Both axial ends of the shaft 52c are supported movably (rotatably) by bearing members such as bearings.

[0020] A plurality of (eight) permanent magnets 52b are embedded in the mover core 52a. Specifically, a plurality of magnet housing sections are provided in the mover core 52a at equal intervals in the circumferential direction. A predetermined number of magnetic pole pairs (eight, four magnetic pole pairs in this embodiment) of permanent magnets 52b are embedded in the plurality of magnet housing sections. For example, known ferrite magnets, rare earth magnets, etc. may be used as the permanent magnets 52b. The number of slots in the stator 51 and the number of magnetic poles in the mover 52 are not limited.

[0021] The control device 60 includes a known arithmetic device and a storage device, and configures a control circuit. The control device 60 controls a power conversion system including the power converter 40. For example, the control device 60 can control the opening and closing of a plurality of (six) switching elements (positive pole side switching element 4xp and negative pole side switching element 4xn) of the power converter 40 by pulse width modulation control.

[0022] As shown in Fig. 1, the control device 60 includes a DC voltage sensor 60a, a drive circuit 60b, a current sensor 60c, and a position sensor 60d. The DC voltage sensor 60a detects a DC voltage Vdc of the DC power smoothed by the smoothing capacitor 30. In this specification, the DC voltage Vdc detected by the DC voltage sensor 60a is referred to as a DC voltage detection value Vdc_fb. The drive circuit 60b is a drive circuit that amplifies a drive signal output from the control device 60, and may be, for example, a known driver circuit. For example, when the electric motor 50 is a servo motor, the drive circuit 60b is included in a servo amplifier.

[0023] The current sensor 60c detects an output current output from the power converter 40. The current sensor 60c in the embodiment is provided on the power cable 44u and the power cable 44v, and detects a U-phase current flowing through the power cable 44u and a V-phase current flowing through the power cable 44v. In this specification, the U-phase current detected by the current sensor 60c is referred to as a U-phase current detection value Iu_fb, and the V-phase current detected by the current sensor 60c is referred to as a V-phase current detection value Iv_fb. The W-phase current flowing through the power cable 44w is calculated by subtracting the U-phase current detection value Iu_fb and the V-phase current detection value Iv_fb from zero. The current sensor 60c can be a known current detector (for example, a current detector using a current transformer, a current detector using a shunt resistor, etc.).

[0024] The position sensor 60d detects the position of the mover 52 relative to the stator 51. A known position sensor (e.g., an encoder, a resolver, a Hall sensor, etc.) can be used as the position sensor 60d. In this specification, the position of the mover 52 detected by the position sensor 60d (when the motor 50 is a cylindrical motor, the rotational position) is referred to as the mover position θ. Note that the control device 60 can be equipped with various sensors in addition to the sensors already described.

[0025] The arithmetic unit of the control device 60 reads out the control program for the power converter 40 stored in the storage device and executes the control program. The detection values ​​and the like described above are input to the control device 60 via an insulating unit. The arithmetic unit outputs an opening / closing signal to each switching element of the power converter 40 via the insulating unit and a drive circuit 60b shown in FIG. 1 to control the opening and closing of the power converter 40. The insulating unit electrically insulates the low-voltage side circuit including the control device 60 from the high-voltage side circuit including the power source 20. The insulating unit can be, for example, a known photocoupler.

[0026] 1-2. Example of control by the control device 60 As shown in FIG. 3, the control device 60 of the embodiment, when considered as a control block, includes a three-phase / two-phase conversion unit 61, an angular velocity calculation unit 62, a position control unit 63, a speed control unit 64, a q-axis current control unit 65, a d-axis current control unit 66, a two-phase / three-phase conversion unit 67, and a magnetic pole detection command unit 68, and is capable of performing vector control.

[0027] 2, the field direction (main magnetic flux direction) of the mover magnetic poles (permanent magnets 52b in this embodiment) of the motor 50 is defined as the d-axis direction, and the direction (torque direction) electrically perpendicular to the d-axis direction is defined as the q-axis direction. The motor 50 in this embodiment is an eight-pole motor, and for convenience of illustration, the angle (electrical angle of 90 degrees) between the d-axis direction and the q-axis direction is shown as 22.5 degrees (mechanical angle). Furthermore, the voltage equation in the d-axis-q-axis coordinate system of an embedded magnet type synchronous motor in which the permanent magnets 52b are embedded in the mover 52 can be expressed by (Equation 1).

[0028]

number

[0029] However, the voltage in the d-axis direction is represented by d-axis voltage Vd, and the voltage in the q-axis direction is represented by q-axis voltage Vq. Furthermore, the winding resistance of each coil (U-phase coil 51u, V-phase coil 51v, W-phase coil 51w) is represented by winding resistance R. Furthermore, the d-axis inductance is represented by d-axis inductance Ld, and the q-axis inductance is represented by q-axis inductance Lq. Furthermore, the current in the d-axis direction is represented by d-axis current Id, and the current in the q-axis direction is represented by q-axis current Iq. Furthermore, the angular velocity of the mover 52 is represented by angular velocity ω, and the induced voltage constant is represented by induced voltage constant Φ. Furthermore, the differential operator is represented by differential operator p (=d / dt).

[0030] The control device 60 sets, for example, a d-axis voltage command Vd_ref based on a d-axis current command Id_ref, and sets a q-axis current command Iq_ref and a q-axis voltage command Vq_ref based on a position command θ_ref to drive and control the power converter 40. Here, the d-axis current command Id_ref refers to a current command in the d-axis direction, and the q-axis current command Iq_ref refers to a current command in the q-axis direction. The d-axis voltage command Vd_ref refers to a voltage command in the d-axis direction, and the q-axis voltage command Vq_ref refers to a voltage command in the q-axis direction. Furthermore, the position command θ_ref refers to a position command (electrical angle) of the mover 52.

[0031] 1-2-1. Three-phase / two-phase conversion unit 61 The three-phase / two-phase converter 61 calculates a d-axis current calculated value Id_fb and a q-axis current calculated value Iq_fb. Here, the d-axis current calculated value Id_fb refers to a calculated current value in the d-axis direction, and the q-axis current calculated value Iq_fb refers to a calculated current value in the q-axis direction. As shown in FIG. 3, the three-phase / two-phase converter 61 receives a U-phase current detection value Iu_fb and a V-phase current detection value Iv_fb detected by the current sensor 60c. As described above, the W-phase current can be calculated by subtracting the U-phase current detection value Iu_fb and the V-phase current detection value Iv_fb from zero. The detection value (calculated value) of the W-phase current is the W-phase current detection value Iw_fb. The three-phase / two-phase converter 61 also receives a mover position θ detected by the position sensor 60d.

[0032] The three-phase / two-phase conversion unit 61 calculates the d-axis current calculated value Id_fb and the q-axis current calculated value Iq_fb based on (Equation 2) using the U-phase current detection value Iu_fb, the V-phase current detection value Iv_fb, and the W-phase current detection value Iw_fb, as well as the mover position θ. Note that the mover position θ can also be estimated from, for example, changes over time in the U-phase current detection value Iu_fb, the V-phase current detection value Iv_fb, and the W-phase current detection value Iw_fb. The mover position θ can also be estimated from, for example, changes over time in the induced voltage of each phase. In the embodiment, the mover position θ is detected by the position sensor 60d.

[0033]

number

[0034] 1-2-2. Angular velocity calculation unit 62 The angular velocity calculation unit 62 calculates the angular velocity calculation value ω_fb. Here, the angular velocity calculation value ω_fb refers to a calculated value of the angular velocity ω. As shown in FIG. 3, the mover position θ detected by the position sensor 60d is input to the angular velocity calculation unit 62. For example, the angular velocity calculation unit 62 can calculate the mover velocity by time differentiating the mover position θ, and calculate the angular velocity ω from the mover velocity to calculate the angular velocity calculation value ω_fb. The control device 60 can also detect the mover velocity using a known detector.

[0035] 1-2-3. Position control unit 63 Position control unit 63 calculates an angular velocity command ω_ref based on the position command θ_ref and the mover position θ. Here, the angular velocity command ω_ref refers to a command for the angular velocity ω. Specifically, position control unit 63 calculates the angular velocity command ω_ref so that the mover position θ coincides with the position command θ_ref. Position control unit 63 may take various forms as long as it is able to calculate the angular velocity command ω_ref as described above.

[0036] 3, position control unit 63 includes a subtractor 63a. A position command θ_ref and a mover position θ are input to subtractor 63a. Subtractor 63a subtracts the mover position θ from the position command θ_ref to calculate a deviation Δθ. For example, position control unit 63 receives the deviation Δθ as an input and calculates an angular velocity command ω_ref by at least one of proportional control (P control), integral control (I control), and differential control (D control). That is, position control unit 63 can calculate angular velocity command ω_ref by performing known P control, PI control, PID control, or the like.

[0037] 1-2-4. Speed ​​control section 64 The speed control unit 64 calculates the q-axis current command Iq_ref based on the angular velocity command ω_ref and the angular velocity calculation value ω_fb. Specifically, the speed control unit 64 calculates the q-axis current command Iq_ref so that the angular velocity calculation value ω_fb matches the angular velocity command ω_ref. The speed control unit 64 may take various forms as long as it is able to calculate the q-axis current command Iq_ref as described above.

[0038] As shown in Fig. 3, the speed control unit 64 includes a subtractor 64a. An angular velocity command ω_ref and an angular velocity calculation value ω_fb are input to the subtractor 64a. The subtractor 64a subtracts the angular velocity calculation value ω_fb from the angular velocity command ω_ref to calculate a deviation Δω. For example, the speed control unit 64 receives the deviation Δω as an input and calculates the q-axis current command Iq_ref by at least one of proportional control (P control), integral control (I control), and differential control (D control). That is, the speed control unit 64 can calculate the q-axis current command Iq_ref by performing known P control, PI control, PID control, or the like.

[0039] 1-2-5. q-axis current control section 65 and d-axis current control section 66 The q-axis current control unit 65 calculates the q-axis voltage command Vq_ref based on the q-axis current command Iq_ref and the q-axis current calculated value Iq_fb. Specifically, the q-axis current control unit 65 calculates the q-axis voltage command Vq_ref so that the q-axis current calculated value Iq_fb matches the q-axis current command Iq_ref. The q-axis current control unit 65 may take various forms as long as it is able to calculate the q-axis voltage command Vq_ref as described above.

[0040] As shown in Fig. 3, the q-axis current control unit 65 includes a subtractor 65a. The subtractor 65a receives the q-axis current command Iq_ref and the q-axis current calculation value Iq_fb. The subtractor 65a subtracts the q-axis current calculation value Iq_fb from the q-axis current command Iq_ref to calculate the deviation ΔIq. For example, the q-axis current control unit 65 receives the deviation ΔIq as an input and calculates the q-axis voltage command Vq_ref by at least one of proportional control (P control), integral control (I control), and differential control (D control). That is, the q-axis current control unit 65 can calculate the q-axis voltage command Vq_ref by performing known P control, PI control, PID control, or the like.

[0041] Similarly, the d-axis current control unit 66 calculates the d-axis voltage command Vd_ref based on the d-axis current command Id_ref and the d-axis current calculated value Id_fb. Specifically, the d-axis current control unit 66 calculates the d-axis voltage command Vd_ref so that the d-axis current calculated value Id_fb matches the d-axis current command Id_ref. The d-axis current control unit 66 may take various forms as long as it is able to calculate the d-axis voltage command Vd_ref as described above.

[0042] As shown in Fig. 3, the d-axis current control unit 66 includes a subtractor 66a. The subtractor 66a receives the d-axis current command Id_ref and the d-axis current calculation value Id_fb. The subtractor 66a subtracts the d-axis current calculation value Id_fb from the d-axis current command Id_ref to calculate the deviation ΔId. For example, the d-axis current control unit 66 receives the deviation ΔId as an input and calculates the d-axis voltage command Vd_ref by at least one of proportional control (P control), integral control (I control), and differential control (D control). That is, the d-axis current control unit 66 can calculate the d-axis voltage command Vd_ref by performing known P control, PI control, PID control, or the like.

[0043] 1-2-6. Two-phase / three-phase converter 67 A two-phase / three-phase conversion unit 67 calculates three-phase voltage commands (U-phase voltage command Vu_ref, V-phase voltage command Vv_ref, and W-phase voltage command Vw_ref) from two-phase voltage commands (d-axis voltage command Vd_ref and q-axis voltage command Vq_ref), where the U-phase voltage command Vu_ref refers to the voltage command for the U phase, the V-phase voltage command Vv_ref refers to the voltage command for the V phase, and the W-phase voltage command Vw_ref refers to the voltage command for the W phase.

[0044] 3, the two-phase / three-phase converter 67 receives the d-axis voltage command Vd_ref calculated by the d-axis current controller 66 and the q-axis voltage command Vq_ref calculated by the q-axis current controller 65. The two-phase / three-phase converter 67 also receives the mover position θ detected by the position sensor 60d. The two-phase / three-phase converter 67 performs inverse conversion in the d-axis-q-axis coordinate system using the d-axis voltage command Vd_ref, the q-axis voltage command Vq_ref, and the mover position θ to calculate a U-phase voltage command Vu_ref, a V-phase voltage command Vv_ref, and a W-phase voltage command Vw_ref.

[0045] The drive circuit 60b receives a U-phase voltage command Vu_ref, a V-phase voltage command Vv_ref, a W-phase voltage command Vw_ref, a DC voltage detection value Vdc_fb detected by the DC voltage sensor 60a, etc. The drive circuit 60b generates opening / closing signals (pulse signals) for a plurality of (six) switching elements (positive pole side switching element 4xp and negative pole side switching element 4xn) of the power converter 40 based on the U-phase voltage command Vu_ref, the V-phase voltage command Vv_ref, the W-phase voltage command Vw_ref, the DC voltage detection value Vdc_fb, etc.

[0046] 1-3. Configuration example of magnetic pole position estimation device 70 When controlling the electric motor 50 using the position sensor 60d, it is necessary to estimate the magnetic pole position 52p of the mover 52 in order to grasp the positional relationship between the magnetic pole position 52p of the mover 52 and the position sensor 60d.

[0047] For example, when the position sensor 60d is attached or detached, the positional relationship between the magnetic pole position 52p of the mover 52 and the position sensor 60d (the relationship between the magnetic pole position 52p of the mover 52 and the reference position of the position sensor 60d) becomes unclear. Therefore, when the position sensor 60d is attached, it is necessary to grasp the above positional relationship again. As shown in Fig. 2, the magnetic pole position 52p of the mover 52 is the reference position of the permanent magnets 52b for a predetermined number of magnetic pole pairs (in this embodiment, four magnetic pole pairs, i.e., eight), and can be the position of a predetermined permanent magnet 52b (mover magnetic pole).

[0048] As shown in Fig. 4, the magnetic pole position estimation device 70 includes a voltage command setting unit 71, a first calculation unit 72, and a second calculation unit 73, and estimates the magnetic pole position 52p of the mover 52. The voltage command setting unit 71, the first calculation unit 72, and the second calculation unit 73 can be provided in various arithmetic devices, control devices, management devices, etc. For example, at least one of the voltage command setting unit 71, the first calculation unit 72, and the second calculation unit 73 can be provided in the control device 60 shown in Fig. 1. At least one of the voltage command setting unit 71, the first calculation unit 72, and the second calculation unit 73 can also be formed on the cloud.

[0049] In the embodiment, the voltage command setting unit 71, the first calculation unit 72, and the second calculation unit 73 are provided in the control device 60. Moreover, the magnetic pole position estimation device 70 executes control according to the flowchart shown in FIG. 5. Specifically, the voltage command setting unit 71 performs the process shown in step S11. The first calculation unit 72 performs the processes and judgments shown in steps S12 to S17. The second calculation unit 73 performs the process shown in step S18. The matters described in this specification can be appropriately selected and applied. Moreover, the matters described in this specification can be appropriately combined.

[0050] 1-3-1. Voltage command setting unit 71 The voltage command setting unit 71 sets a plurality of d-axis voltage commands Vd_ref, which are voltage commands in the d-axis direction, with different voltage command values ​​(step S11). The voltage command setting unit 71 may take various forms as long as it can set a plurality of d-axis voltage commands Vd_ref with different voltage command values. FIG. 6 shows an example of the change over time of the d-axis voltage command Vd_ref. The vertical axis of the figure indicates the d-axis voltage command Vd_ref, and the horizontal axis indicates time. The broken line L1 shows an example of the change over time of the d-axis voltage command Vd_ref. It is assumed that at time T0, the mover 52 is stationary with respect to the stator 51.

[0051] The voltage command setting unit 71 sets the d-axis current command Id_ref to a first predetermined value (constant value) at time T0. As a result, the d-axis voltage command Vd_ref increases at a constant rate of increase, reaches the voltage V11 at time T11, and is set to the constant voltage V11. The d-axis voltage command Vd_ref is set to the voltage V11 from time T11 to time T12. The voltage command setting unit 71 sets the d-axis current command Id_ref to a second predetermined value (constant value) greater than the first predetermined value at time T12. As a result, the d-axis voltage command Vd_ref increases at a constant rate of increase, reaches the voltage V12 at time T13, and is set to the constant voltage V12. The d-axis voltage command Vd_ref is set to the voltage V12 from time T13 to time T14.

[0052] At time T14, the voltage command setting unit 71 sets the d-axis current command Id_ref to a third predetermined value (constant value) that is greater than the second predetermined value. As a result, the d-axis voltage command Vd_ref increases at a constant rate of increase, reaches voltage V13 at time T15, and is set to the constant voltage V13. The d-axis voltage command Vd_ref is set to voltage V13 from time T15 to time T16. At time T16, the voltage command setting unit 71 sets the d-axis current command Id_ref to zero. As a result, the d-axis voltage command Vd_ref decreases at a constant rate of decrease, becomes zero at time T17, and is set to zero thereafter.

[0053] In this manner, the voltage command setting unit 71 can set a plurality of d-axis voltage commands Vd_ref (three in the above example) having different voltage command values ​​(see broken line L1 in FIG. 6). Note that the voltage command setting unit 71 can also set two d-axis voltage commands Vd_ref. Also, the voltage command setting unit 71 can also set four or more d-axis voltage commands Vd_ref.

[0054] 1-3-2.First calculation section 72 The first calculation unit 72 calculates a tentative magnetic pole position AP0 by estimating the magnetic pole position 52p of the mover 52 for each d-axis voltage command Vd_ref set by the voltage command setting unit 71 (steps S12 to S17). For each d-axis voltage command Vd_ref, the first calculation unit 72 applies a d-axis voltage Vd, which is a voltage in the d-axis direction, based on the d-axis voltage command Vd_ref, and vibrates the mover 52 with a predetermined amplitude and frequency relative to the stator 51 to calculate the tentative magnetic pole position AP0. The amplitude and frequency at which the mover 52 is vibrated can be set arbitrarily.

[0055] 7 shows an example of the change over time of the position command θ_ref of the mover 52. The vertical axis in the figure indicates the position command θ_ref of the mover 52, and the horizontal axis indicates time. A curve L2 shows an example of the change over time of the position command θ_ref of the mover 52. As described above, the d-axis voltage command Vd_ref is set to a constant voltage V11 from time T11 to time T12 by the voltage command setting unit 71. As a result, the constant voltage V11 is applied to the d-axis voltage Vd from time T11 to time T12 (step S12).

[0056] The first calculation unit 72 vibrates the mover 52 at a predetermined amplitude and frequency in a state where the voltage V11 is applied as the d-axis voltage Vd (step S13). Specifically, the first calculation unit 72 sinusoidally changes the position command θ_ref in the negative and positive directions with reference to the rest position (0 position in the figure) of the mover 52 during the period from time T11a, which is later than time T11, to time T12. In the figure, the minimum value of the position command θ_ref is indicated by the position θ11, which is a negative value, and the maximum value of the position command θ_ref is indicated by the position θ12, which is a positive value. In addition, the position command θ_ref can be varied by any period of a sine wave. In the embodiment, the position command θ_ref varies, for example, by five periods of a sine wave.

[0057] The voltage command setting unit 71 can apply a d-axis voltage Vd based on a d-axis voltage command Vd_ref using, for example, a magnetic pole detection command unit 68 shown in Fig. 3, and vibrate the mover 52 with respect to the stator 51 at a predetermined amplitude and frequency. The magnetic pole detection command unit 68 generates each command (position command θ_ref shown in Fig. 7, d-axis voltage command Vd_ref shown in Fig. 6, and q-axis voltage command Vq_ref set to zero) when detecting the magnetic pole. The magnetic pole detection command unit 68 also includes switches 68a, 68b, and 68c.

[0058] When detecting a magnetic pole, the switch 68a switches the mover position θ detected by the position sensor 60d to the position command θ_ref shown in Fig. 7 so that it can be input to the two-phase / three-phase conversion unit 67. When detecting a magnetic pole, the switch 68b switches the d-axis voltage command Vd_ref calculated by the d-axis current control unit 66 to the d-axis voltage command Vd_ref shown in Fig. 6 so that it can be input to the two-phase / three-phase conversion unit 67. When detecting a magnetic pole, the switch 68c switches the q-axis voltage command Vq_ref calculated by the q-axis current control unit 65 to zero so that it can be input to the two-phase / three-phase conversion unit 67. The magnetic pole detection command unit 68 can generate a rotating magnetic field by the position command θ_ref shown in Fig. 7 to vibrate the mover 52.

[0059] The above also applies to the case where the d-axis voltage command Vd_ref is set to the voltage V12. The first calculation unit 72 vibrates the mover 52 with the same amplitude and the same frequency as the above-mentioned amplitude during the period from time T13a, which is later than time T13, to time T14 in a state where the voltage V12 is applied as the d-axis voltage Vd. The above also applies to the case where the d-axis voltage command Vd_ref is set to the voltage V13. The first calculation unit 72 vibrates the mover 52 with the same amplitude and the same frequency as the above-mentioned amplitude during the period from time T15a, which is later than time T15, to time T16 in a state where the voltage V13 is applied as the d-axis voltage Vd. In this way, the first calculation unit 72 applies the d-axis voltage Vd based on the d-axis voltage command Vd_ref for each d-axis voltage command Vd_ref, and can vibrate the mover 52 with respect to the stator 51 at a predetermined amplitude and frequency.

[0060] A rotating magnetic field is generated by the position command θ_ref shown in Fig. 7. The first calculation unit 72 can estimate the magnetic pole position 52p of the mover 52 based on the rotating magnetic field, and can calculate a tentative magnetic pole position AP0. For example, the first calculation unit 72 calculates the maximum and minimum values ​​in one period of the electrical angle, which are detection results of the position sensor 60d that detects the position of the mover 52 relative to the stator 51, for a predetermined number of periods, and calculates the average value of the calculated maximum and minimum values ​​for the predetermined number of periods as the tentative magnetic pole position AP0.

[0061] FIG. 8 shows an example of the change over time in the detection result of the position sensor 60d. The vertical axis of the figure shows the detection result of the position sensor 60d, and the horizontal axis shows time. A curve L3 shows an example of the change over time in the detection result of the position sensor 60d. Specifically, the curve L3 shows an example of a response to the position command θ_ref shown in the curve L2 of FIG. 7. For example, the detection result of the position sensor 60d fluctuates from time T11b, which is later than time T11a, to time T12a, which is later than time T12.

[0062] In the example shown in Fig. 7, the position command θ_ref fluctuates for five periods of the sine wave. In Fig. 8, the maximum and minimum values ​​of the detection result of the position sensor 60d in one period of the electrical angle are indicated by a maximum value M11 and a minimum value N11 for the first period (step S14). The same is true for the remaining four periods (if No in step S15), and the maximum and minimum values ​​of the detection result are indicated by a maximum value M12 and a minimum value N12, a maximum value M13 and a minimum value N13, a maximum value M14 and a minimum value N14, and a maximum value M15 and a minimum value N15 (step S14).

[0063] When the maximum and minimum values ​​for a predetermined number of cycles (five cycles in the above example) are calculated and recorded (Yes in step S15), the first calculation unit 72 calculates the average value of the calculated maximum values ​​(maximum value M11 to maximum value M15) and minimum values ​​(minimum value N11 to minimum value N15) for the predetermined number of cycles as a tentative magnetic pole position AP0. The average value is obtained by dividing the above 10 calculated values ​​by the number 10, and the same applies below. For ease of explanation, the above tentative magnetic pole position AP0 is set as a tentative magnetic pole position AP1 (step S16).

[0064] Similarly, the detection result of position sensor 60d fluctuates from time T13b, which is later than time T13a, to time T14a, which is later than time T14. The maximum and minimum values ​​of the detection result in one period of the electrical angle are indicated by maximum value M21 and minimum value N21, maximum value M22 and minimum value N22, maximum value M23 and minimum value N23, maximum value M24 and minimum value N24, and maximum value M25 and minimum value N25 (Step S14 if No in Step S17).

[0065] When the maximum and minimum values ​​for a predetermined number of cycles (five cycles in the above example) are calculated and recorded (Yes in step S15), the first calculation unit 72 calculates an average value of the calculated maximum values ​​(maximum value M21 to maximum value M25) and minimum values ​​(minimum value N21 to minimum value N25) for the predetermined number of cycles as a tentative magnetic pole position AP0. For ease of explanation, the tentative magnetic pole position AP0 is set as a tentative magnetic pole position AP2 (step S16 if No in step S17).

[0066] Furthermore, the detection result of position sensor 60d fluctuates from time T15b, which is later than time T15a, to time T16a, which is later than time T16. The maximum and minimum values ​​of the detection result in one period of the electrical angle are indicated by maximum value M31 and minimum value N31, maximum value M32 and minimum value N32, maximum value M33 and minimum value N33, maximum value M34 and minimum value N34, and maximum value M35 and minimum value N35 (Step S14 if No in Step S17).

[0067] When the maximum and minimum values ​​for a predetermined number of cycles (five cycles in the above example) are calculated and recorded (Yes in step S15), the first calculation unit 72 calculates an average value of the calculated maximum values ​​(maximum values ​​M31 to M35) and minimum values ​​(minimum values ​​N31 to N35) for the predetermined number of cycles as a tentative magnetic pole position AP0. For ease of explanation, the tentative magnetic pole position AP0 is set as a tentative magnetic pole position AP3 (step S16). In this manner, tentative magnetic pole positions AP0 are calculated for each of the predetermined (three in the above example) d-axis voltage commands Vd_ref (Yes in step S17), and the control by the magnetic pole position estimation device 70 proceeds to the process shown in step S18.

[0068] 1-3-3.Second calculation section 73 9 shows an example of the relationship between the d-axis voltage command Vd_ref and the tentative magnetic pole position AP0. The vertical axis in the figure indicates the magnetic pole position 52p of the mover 52, and the horizontal axis indicates the d-axis voltage command Vd_ref expressed in common logarithm. As described above, when the d-axis voltage command Vd_ref is set to the voltage V11, the tentative magnetic pole position AP0 is the tentative magnetic pole position AP1. When expressed in common logarithm, the voltage V11 is represented by the voltage V21. The circles in the figure indicate the position on the graph of the tentative magnetic pole position AP1 with respect to the voltage V21.

[0069] Similarly, when the d-axis voltage command Vd_ref is set to voltage V12, the tentative magnetic pole position AP0 is tentative magnetic pole position AP2. When expressed in common logarithm, the voltage V12 is represented as voltage V22. The square marks in the figure indicate the position on the graph of the tentative magnetic pole position AP2 for the voltage V22. Furthermore, when the d-axis voltage command Vd_ref is set to voltage V13, the tentative magnetic pole position AP0 is tentative magnetic pole position AP3. When expressed in common logarithm, the voltage V13 is represented as voltage V23. The triangle marks in the figure indicate the position on the graph of the tentative magnetic pole position AP3 for the voltage V23.

[0070] 9 indicates the correct magnetic pole position 52p of the mover 52. As shown in the figure, the smaller the d-axis voltage command Vd_ref, the farther the tentative magnetic pole position AP0 is from the correct magnetic pole position 52p of the mover 52. When the d-axis voltage command Vd_ref is increased, the tentative magnetic pole position AP0 approaches the correct magnetic pole position 52p of the mover 52. However, in an actual device, there is a limit to the voltage that can be applied, and it is difficult to make the tentative magnetic pole position AP0 coincide with the correct magnetic pole position 52p of the mover 52.

[0071] Therefore, the second calculation unit 73 calculates an estimated magnetic pole position EP0 by estimating the magnetic pole position 52p of the mover 52, based on the relationship between the d-axis voltage command Vd_ref set by the voltage command setting unit 71 and the tentative magnetic pole position AP0 calculated by the first calculation unit 72 (step S18). The second calculation unit 73 may take various forms as long as it is able to calculate the estimated magnetic pole position EP0 based on the relationship between the d-axis voltage command Vd_ref and the tentative magnetic pole position AP0.

[0072] For example, in the relationship between the d-axis voltage command Vd_ref and the tentative magnetic pole position AP0, the second calculation unit 73 can calculate the estimated magnetic pole position EP0 using a predetermined function F(Vd_ref) with which an approximation curve of the tentative magnetic pole position AP0 with respect to the d-axis voltage command Vd_ref asymptotically approaches a steady value. A curve L4 in Fig. 9 shows an example of an approximation curve of the tentative magnetic pole position AP0 with respect to the d-axis voltage command Vd_ref. The curve L4 asymptotically approaches the estimated magnetic pole position EP0, which is a steady value, and the second calculation unit 73 can calculate the steady value as the estimated magnetic pole position EP0.

[0073] The predetermined function F(Vd_ref) may be any function that approximates the tentative magnetic pole position AP0 with respect to the d-axis voltage command Vd_ref and asymptotically approaches a steady value, and various functions may be used. For example, the predetermined function F(Vd_ref) may be expressed by an exponential function, a higher-order function, a fractional function, a hyperbolic function, or the like. The approximate curve shown by the curve L4 may be expressed by an exponential function. Specifically, the predetermined function F(Vd_ref) may be expressed by (Equation 3). However, the magnetic pole position is expressed by the magnetic pole position X. In this way, the predetermined function F(Vd_ref) may be expressed by an exponential function using the coefficients A and B, and the natural logarithm exp.

[0074]

number

[0075] The second calculation unit 73 can derive the coefficient A and the coefficient B by various methods to calculate the estimated magnetic pole position EP0. For example, the second calculation unit 73 can calculate the estimated magnetic pole position EP0 by the least squares method. The least squares method calculates the coefficients of the approximation curve (coefficient A and coefficient B in the above example) so that the sum of squares of the deviation between the predetermined function F(Vd_ref) and the measurement points is minimized.

[0076] FIG. 10 is an enlarged view of a part of FIG. 9. In FIG. 10, the deviation between the predetermined function F(Vd_ref) representing the curve L4 and the tentative magnetic pole position AP1 is indicated by the deviation DF1. Similarly, the deviation between the predetermined function F(Vd_ref) and the tentative magnetic pole position AP2 is indicated by the deviation DF2. Moreover, the deviation between the predetermined function F(Vd_ref) and the tentative magnetic pole position AP3 is indicated by the deviation DF3. The second calculation unit 73 determines the coefficients A and B so that the sum of squares obtained by adding the squares of the deviations DF1, DF2, and DF3 is minimized. In this case, the estimated magnetic pole position EP0 is the coefficient A, and can be expressed by (Equation 4).

[0077]

number

[0078] The predetermined function F(Vd_ref) can also be expressed as a fractional function. For example, the magnetic force generated in the coils (U-phase coil 51u, V-phase coil 51v, W-phase coil 51w) of the electric motor 50 is proportional to the current flowing through the coil. As the vibration frequency of the position command θ_ref used to estimate the magnetic pole position 52p becomes smaller, the voltage applied to the coil and the current flowing through the coil can be considered to be proportional, and it can be said that the voltage applied to the coil and the magnetic force generated in the coil are proportional.

[0079] Furthermore, when the mover 52 is near the magnetic pole position, the magnetic attractive force is proportional to the distance from the magnetic pole position to the mover 52, and an equation of motion can be derived. The equation of motion in this case can be expressed by (Equation 5). Here, coefficient K is a proportionality coefficient between the voltage command of the voltage applied to the coil and the magnetic attractive force, coefficient G is a constant, and coefficient J represents the inertia of the mover 52. Furthermore, the magnetic pole position is represented by magnetic pole position X. The magnetic pole position when the motion system represented by (Equation 5) has sufficiently damped and a sufficient amount of time has passed without vibrating can be expressed by (Equation 6), and can be expressed by a fractional function that asymptotically approaches the estimated magnetic pole position EP0.

[0080]

number

[0081]

number

[0082] When an external force F0 is applied to the mover 52, the position sensor 60d detects the position of the mover 52 to which the external force F0 is applied relative to the stator 51. For example, the external force F0 is gravity. Gravity acts downward in the vertical direction (Z direction). Therefore, when the output torque of the motor 50 is the same and the mover 52 is moved downward in the vertical direction (Z direction), the mover 52 moves more easily than when the mover 52 is moved upward in the vertical direction (Z direction). The same situation occurs when the first calculation unit 72 vibrates the mover 52 along the vertical direction (Z direction) at a predetermined amplitude and frequency to calculate the tentative magnetic pole position AP0.

[0083] As a result, as shown in Fig. 9, due to gravity, the tentative magnetic pole position AP0 is estimated to be lower in the vertical direction (Z direction) than the 0 position (correct magnetic pole position 52p of the mover 52) shown in the same figure. Even in such a situation, the second calculation unit 73 can calculate the estimated magnetic pole position EP0 based on the relationship between the d-axis voltage command Vd_ref and the tentative magnetic pole position AP0. The estimated magnetic pole position EP0 is sufficiently closer to the 0 position (correct magnetic pole position 52p of the mover 52) than the tentative magnetic pole position AP0. Therefore, the magnetic pole position estimation device 70 can improve the estimation accuracy of the magnetic pole position.

[0084] The external force F0 is not limited to gravity. For example, the position sensor 60d can detect the position of the mover 52 relative to the stator 51 to which the external force F0 acting in the horizontal direction is applied. In this case, the tentative magnetic pole position AP0 is likely to be displaced in the direction in which the external force F0 acts among the moving directions of the mover 52 that is movable in the horizontal direction. Even in such a situation, the second calculator 73 can calculate the estimated magnetic pole position EP0 based on the relationship between the d-axis voltage command Vd_ref and the tentative magnetic pole position AP0.

[0085] The magnetic pole position estimation device 70 can be applied to various electric motor control systems 10. For example, when the external force F0 described above is gravity, the electric motor 50 can drive the robot arm 820a extending along the vertical direction (Z direction) against gravity. An example of a system equipped with the above-mentioned robot arm 820a is an ultrasonic diagnostic system 810.

[0086] 1-4. Example of the configuration of the ultrasound diagnostic system 810 11 shows an example of an ultrasound diagnostic system 810. In the figure, the extension direction of the horizontal portion 821b of the first extension portion 821 is defined as the X direction. The direction perpendicular to the X direction on the horizontal plane is defined as the Y direction. Furthermore, the direction perpendicular to the X direction and the Y direction is defined as the vertical direction (Z direction).

[0087] The ultrasonic diagnostic system 810 is a medical device that performs ultrasonic diagnosis by holding a probe PB0, which is an end effector EF0, on a robot 820 and driving the robot 820 so that the probe PB0 is pressed against an examination target part (e.g., skin) of a subject. The ultrasonic diagnostic system 810 of the embodiment is used for echo diagnosis in which ultrasonic waves are applied to the examination target part of the subject, a cross-sectional image of the examination target part is obtained, and the state of the examination target part is confirmed from the obtained image. As shown in Figs. 11 and 12, the ultrasonic diagnostic system 810 includes a robot 820 and an ultrasonic diagnostic device 100.

[0088] The ultrasound diagnostic device 100 also includes a probe PB0 and a main body 102 to which the probe PB0 is connected via a cable. The main body 102 includes a control unit 103, an input unit 104, an image processing unit 105, and a display unit 106. The control unit 103 controls the entire device. The input unit 104 is used by an examiner to input instructions such as to start diagnosis. The image processing unit 105 processes signals transmitted from the probe PB0 to generate an ultrasound image. The display unit 106 displays the ultrasound image generated by the image processing unit 105.

[0089] The robot 820 includes a robot arm 820a and a robot body 820b. The robot body 820b includes a base 826 and an elevator 840. The robot arm 820a includes a first extension portion 821, a second extension portion 822, a base 825, a first joint shaft 831, a second joint shaft 832, a third joint shaft 833, a first extension portion drive motor 835, a second extension portion drive motor 836, a posture holding device 837, and a three-axis rotation mechanism 850.

[0090] The base end of the first extension portion 821 is connected to the base 825 via the first joint shaft 831. The main body of the first joint shaft 831 is fixed to the base 825, and the rotating portion of the first joint shaft 831 is connected to the base end of the first extension portion 821. The first extension portion drive motor 835 is built into the main body of the first joint shaft 831, and rotates the rotating portion of the first joint shaft 831 around a rotation axis (axis along the vertical direction (Z direction)), thereby rotating (turning) the first extension portion 821 along a horizontal plane (XY plane). The first joint shaft 831 has a built-in position sensor, and the position sensor detects the position (rotation position) of the first extension portion drive motor 835. For the position sensor, for example, a known position sensor such as a rotary encoder can be used.

[0091] The first extension portion 821 includes a vertical portion 821a extending along the vertical direction (Z direction) and a horizontal portion 821b extending horizontally from an upper end of the vertical portion 821a. A lower end of the vertical portion 821a is connected to a rotating portion of the first joint shaft 831. A base end of the horizontal portion 821b is connected to an upper end of the vertical portion 821a, and a tip end of the horizontal portion 821b is connected to a rotating portion of the second joint shaft 832. Note that the first extension portion 821 may omit the vertical portion 821a.

[0092] The base end of the second extension portion 822 is connected to the tip end of the first extension portion 821 via the second joint shaft 832. The main body of the second joint shaft 832 is fixed to the base end of the second extension portion 822, and the rotating portion of the second joint shaft 832 is connected to the tip end of the first extension portion 821. The second extension portion drive motor 836 is built into the main body of the second joint shaft 832, and rotates the rotating portion of the second joint shaft 832 around a rotation axis (axis along the vertical direction (Z direction)), thereby rotating (turning) the first extension portion 821 along a horizontal plane (XY plane). The second joint shaft 832 has a built-in position sensor, and the position sensor detects the position (rotation position) of the second extension portion drive motor 836. For the position sensor, for example, a known position sensor such as a rotary encoder can be used.

[0093] The lifting device 840 is installed on a base 826, and lifts and lowers the base 825 relative to the base 826. The base 826 is provided with wheels 826a. As shown in FIG. 11 and FIG. 12, the lifting device 840 includes a slider 841, a guide member 842, a ball screw shaft 843, and a lifting drive motor 844. The slider 841 is fixed to the base 825. The guide member 842 is fixed to the base 826 and provided along the vertical direction (Z direction), and guides the movement of the slider 841. The ball screw shaft 843 is an elevator shaft provided along the vertical direction (Z direction), and a ball screw nut fixed to the slider 841 is rotatably connected to the ball screw shaft 843. The lifting drive motor 844 drives the ball screw shaft 843 to rotate.

[0094] The lifting device 840 rotates a ball screw shaft 843 using a lifting drive motor 844, thereby moving a base 825 fixed to a slider 841 in the vertical direction (Z direction) along a guide member 842. The lifting device 840 has a built-in position sensor, which detects the position (lift position) of the lifting drive motor 844. The position sensor may be, for example, a known position sensor such as a linear encoder.

[0095] The three-axis rotating mechanism 850 is connected to the tip of the second extension section 822 via a third joint shaft 833 provided along the vertical direction (Z direction). The three-axis rotating mechanism 850 includes a first rotation shaft 851, a second rotation shaft 852, and a third rotation shaft 853 which is a tip shaft and which are perpendicular to each other, a first rotation shaft drive motor 855 which rotates the first rotation shaft 851, a second rotation shaft drive motor 856 which rotates the second rotation shaft 852, and a tip shaft drive device 860 which drives the third rotation shaft 853. The first rotation shaft 851 is supported in an orthogonal orientation with respect to the third joint shaft 833. The second rotation shaft 852 is supported in an orthogonal orientation with respect to the first rotation shaft 851. The third rotation shaft 853 is supported in an orthogonal orientation with respect to the second rotation shaft 852. The third rotation shaft 853 holds a probe PB0 as an end effector EF0 so as to be coaxial with the third rotation shaft 853.

[0096] The three-axis rotating mechanism 850 includes a first position sensor and a second position sensor. The first position sensor detects the position (rotational position) of the first rotating shaft drive motor 855. The second position sensor detects the position (rotational position) of the second rotating shaft drive motor 856. The tip shaft drive device 860 includes a drive motor that drives and rotates the third rotating shaft 853, and a third position sensor that detects the position (rotational position) of the drive motor. The first position sensor, the second position sensor, and the third position sensor can be, for example, a known position sensor such as a rotary encoder.

[0097] In the embodiment, the robot 820 can move the probe PB0 of the third rotation axis 853 to an arbitrary position in an arbitrary posture by a combination of translational motion and rotational motion. The translational motion refers to motion in three directions, the X direction, the Y direction, and the vertical direction (Z direction), by the first extension unit drive motor 835, the second extension unit drive motor 836, and the lifting device 840. The rotational motion refers to motion in three directions, around the X axis (pitching), around the Y axis (rolling), and around the Z axis (yawing), by the three-axis rotation mechanism 850.

[0098] The attitude holding device 837 is built into the third joint shaft 833 and includes a motor for holding an attitude. The third joint shaft 833 has a built-in position sensor, which detects the position (rotational position) of the motor for holding an attitude. The position sensor may be, for example, a known position sensor such as a rotary encoder. The attitude holding device 837 holds the attitude of the three-axis rotating mechanism 850 (the orientation of the first rotating shaft 851) in a constant orientation regardless of the orientations of the first extension section 821 and the second extension section 822. The attitude holding device 837 controls the rotation angle of the third joint shaft 833 based on the rotation angle of the first joint shaft 831 and the rotation angle of the second joint shaft 832 so that the axial direction of the first rotating shaft 851 coincides with the X direction. This allows the translational motion in three directions and the rotational motion in three directions to be controlled independently of each other, making the control easier.

[0099] 1-5.Other forms The voltage command setting unit 71 can also apply a d-axis voltage Vd based on a d-axis voltage command Vd_ref using a magnetic pole detection command unit 69 shown in Fig. 13 to vibrate the mover 52 with respect to the stator 51 at a predetermined amplitude and frequency. The magnetic pole detection command unit 69 generates each command for magnetic pole detection (position command θ_ref shown in Fig. 7, d-axis current command Id_ref that increases stepwise corresponding to the voltage change of the d-axis voltage command Vd_ref shown in Fig. 6, and q-axis current command Iq_ref that is set to zero). The magnetic pole detection command unit 69 also includes switches 69a, 69b, and 69c.

[0100] The switch 69a switches the mover position θ detected by the position sensor 60d to the position command θ_ref shown in FIG. 7 during magnetic pole detection, and allows it to be input to the three-phase / two-phase conversion unit 61 and the two-phase / three-phase conversion unit 67. The switch 69b switches the d-axis current command Id_ref output from the upper system to the d-axis current command Id_ref that increases stepwise during magnetic pole detection, and allows it to be input to the subtractor 66a of the d-axis current control unit 66. The switch 69c switches the q-axis current command Iq_ref calculated by the speed control unit 64 to zero during magnetic pole detection, and allows it to be input to the subtractor 65a of the q-axis current control unit 65. Thereby, the current feedback control is performed, and the d-axis voltage command Vd_ref shown in FIG. 6 is generated. The magnetic pole detection command unit 69 can generate a rotating magnetic field by the position command θ_ref shown in FIG. 7 to vibrate the mover 52.

[0101] 2. Magnetic pole position estimation method What has already been described about the magnetic pole position estimation device 70 also applies to the magnetic pole position estimation method. Specifically, the magnetic pole position estimation method includes a voltage command setting step, a first calculation step, and a second calculation step. The voltage command setting step corresponds to the control performed by the voltage command setting unit 71. The first calculation step corresponds to the control performed by the first calculation unit 72. The second calculation step corresponds to the control performed by the second calculation unit 73.

[0102] 3. Examples of Effects of the Embodiments According to the magnetic pole position estimation device 70, a tentative magnetic pole position AP0 is calculated for each of a plurality of d-axis voltage commands Vd_ref, and an estimated magnetic pole position EP0 can be calculated based on the relationship between the d-axis voltage command Vd_ref and the tentative magnetic pole position AP0. What has been described above about the magnetic pole position estimation device 70 also applies to the magnetic pole position estimation method. [Explanation of symbols]

[0103] 50: Electric motor, 51: Stator, 52: Mover, 52p: Magnetic pole position, 60d: position sensor, 70: magnetic pole position estimation device, 71: voltage command setting unit, 72: first calculation unit, 73: second calculation unit, 820a: robot arm, AP0: tentative magnetic pole position, EP0: estimated magnetic pole position, F0: external force, F(Vd_ref): Predetermined function, Vd_ref: d-axis voltage command, Vd: d-axis voltage.

Claims

1. a voltage command setting unit that sets a plurality of d-axis voltage commands, which are voltage commands in a d-axis direction that is a field direction of the motor, so that the voltage command values ​​are different; a first calculation unit that applies a d-axis voltage, which is a voltage in the d-axis direction based on the d-axis voltage command, for each of the d-axis voltage commands set by the voltage command setting unit, and vibrates a mover with respect to a stator at a predetermined amplitude and frequency to calculate a tentative magnetic pole position by estimating a magnetic pole position of the mover; a second calculation unit that calculates an estimated magnetic pole position by estimating a magnetic pole position of the mover based on a relationship between the d-axis voltage command set by the voltage command setting unit and the tentative magnetic pole position calculated by the first calculation unit; and A magnetic pole position estimation device comprising:

2. 2. The magnetic pole position estimation device according to claim 1, wherein the first calculation unit calculates a maximum value and a minimum value in one period of an electrical angle, which are detection results of a position sensor that detects a position of the mover relative to the stator, for a predetermined number of periods, and calculates an average value of the calculated maximum value and minimum value for the predetermined number of periods as the provisional magnetic pole position.

3. 3. The magnetic pole position estimation device according to claim 1, wherein the second calculation unit calculates the estimated magnetic pole position using a predetermined function such that an approximation curve of the provisional magnetic pole position with respect to the d-axis voltage command asymptotically approaches a steady value in a relationship between the d-axis voltage command and the provisional magnetic pole position.

4. 4. The magnetic pole position estimation device according to claim 3, wherein the predetermined function is an exponential function.

5. 4. The magnetic pole position estimation device according to claim 3, wherein the predetermined function is a fractional function.

6. The magnetic pole position estimation device according to claim 3 , wherein the second calculation unit calculates the estimated magnetic pole position by a least squares method.

7. The magnetic pole position estimation device according to claim 1 , wherein the first calculation unit calculates the tentative magnetic pole position using a detection result of a position sensor that detects a position of the mover relative to the stator to which an external force is applied.

8. The magnetic pole position estimation device according to claim 7 , wherein the external force is gravity.

9. 9. The magnetic pole position estimation device according to claim 8, wherein the electric motor drives a robot arm extending in a vertical direction against the force of gravity.

10. a voltage command setting step of setting a plurality of d-axis voltage commands, which are voltage commands in a d-axis direction that is a field direction of the motor, so that the voltage command values ​​are different; a first calculation step of applying a d-axis voltage, which is a voltage in the d-axis direction based on the d-axis voltage command, for each of the d-axis voltage commands set by the voltage command setting step, and vibrating a mover with respect to a stator at a predetermined amplitude and frequency to calculate a tentative magnetic pole position by estimating a magnetic pole position of the mover; a second calculation step of calculating an estimated magnetic pole position by estimating a magnetic pole position of the mover based on a relationship between the d-axis voltage command set in the voltage command setting step and the tentative magnetic pole position calculated in the first calculation step; A magnetic pole position estimation method comprising:

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