Control apparatus, camera platform system, lens unit, image projection apparatus, robot arm, and control method

Abstract

To provide a technique for determining an initial phase of a rotor of a motor so as to pull the rotor in a desired direction even when the rotor cannot rotate in a specific direction.SOLUTION: An initial phase of a rotor of a motor is determined based on whether a change amount of a rotation phase of the rotor detected before and after control of the rotation phase of the rotor is a specified value or not, or whether the change amount is the specified value or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a motor control technique. [Background technology]

[0002] A control method called vector control is known as a method for controlling a motor. In vector control, the motor is controlled based on the rotational phase of the rotor. Therefore, before starting to drive the motor using vector control, it is necessary to determine the initial phase of the rotor.

[0003] Patent Document 1 discloses a method for determining the initial phase of the rotor, in which a predetermined current is supplied to the windings of the motor, and the rotor is attracted by a magnetic field generated by the supplied current. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2018-207733 A Summary of the Invention [Problem to be solved by the invention]

[0005] The technology disclosed in Patent Document 1 has a problem in that the rotor fails to be pulled in if it cannot rotate in the attracting direction due to the influence of the mechanical end of the movable range of the load connected to the motor. The present invention provides a technology for determining the initial phase of a motor rotor so that the rotor is pulled in the desired direction even when the rotor cannot rotate in a specific direction. [Means for solving the problem]

[0006] One aspect of the present invention is characterized in that it comprises a determination means for determining the initial phase of the rotor based on whether the amount of change in the rotational phase of the rotor detected before and after control of the rotational phase of the rotor of the motor is a specified value or is less than or equal to the specified value. [Effects of the Invention]

[0007] According to the present invention, even if the rotor of the motor cannot rotate in a specific direction, the initial phase of the rotor can be determined so as to pull the rotor in a desired direction. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a block diagram showing an example of the configuration of a motor control device 100. [Figure 2] FIG. 2 is a schematic diagram showing a configuration example of a motor 101. [Figure 3] 2 is a diagram illustrating the relationship between the phase of the stator 210 and the angle of the rotor 220. FIG. [Figure 4] FIG. 4 is a diagram for explaining a method of generating a current vector in determining the initial phase of a rotor. [Figure 5] 4 is a flowchart of a process performed by the motor control device 100 to determine the initial phase of the rotor of the motor 101. [Figure 6] FIG. 10 is an explanatory diagram of an example of failure in initial phase determination due to hitting the end of the mechanism. [Figure 7] FIG. 10 is a diagram showing the effect on vector control when a phase shift θ1 occurs. [Figure 8] FIG. 8 is a diagram showing an example of the appearance of a pan head imaging system 800. [Figure 9] FIG. 2 is a block diagram showing an example of the configuration of a lens unit 900. [Figure 10] FIG. 1 is a block diagram showing an example of the configuration of an image projection device 1000. [Figure 11] FIG. 11 is a block diagram showing an example of the configuration of a robot arm 1100. [Figure 12] 4 is a flowchart of a process performed by the motor control device 100 to determine the initial phase of the rotor of the motor 101. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the scope of the invention claimed. Although multiple features are described in the embodiments, not all of these multiple features are necessarily essential to the invention, and multiple features may be combined arbitrarily. Furthermore, in the accompanying drawings, the same reference numerals are used to designate the same or similar components, and redundant explanations will be omitted.

[0010] [First embodiment] The motor control device 100 according to this embodiment makes it possible to determine the initial phase (initial rotation angle) of the rotor even when the motor (rotor) cannot rotate in one direction due to the influence of a mechanical end or the like. An example configuration of the motor control device 100 according to this embodiment will be described using the block diagram of FIG. 1. As shown in FIG. 1, the motor control device 100 includes a motor 101, an angle sensor 102, an operation unit 103, an inverter 104, a load 105, and a control unit 110.

[0011] The motor 101 is a permanent magnet synchronous motor that uses an armature winding as a stator and a permanent magnet as a rotor. The rotor can be rotated by controlling the current flowing through the stator. The motor 101 is connected to a load 105.

[0012] The angle sensor 102 is an incremental rotary encoder for detecting the rotation angle (rotation phase) of the rotor of the motor 101, and outputs pulses according to the rotation amount and rotation speed of the motor.

[0013] The operation unit 103 is a user interface such as a switch or joystick, and by operating the operation unit 103, the user can input operation information related to the control of the motor 101, such as instructions for driving the motor 101, to the motor control device 100.

[0014] The inverter 104 has a switching element that controls the current flowing to each phase coil of the motor 101. The inverter 104 drives the switching element in accordance with a PWM control signal output from the control unit 110, thereby causing a current to flow to each phase coil of the motor 101.

[0015] The load 105 is a load connected to the motor 101, and is, for example, a pan-tilt drive system when the motor control device 100 is applied to a camera-head imaging system. The load 105 has a mechanical end (mechanical end) of its movable range, and if the load 105 hits the mechanical end, the motor 101 will no longer be able to rotate in a particular direction.

[0016] Next, we will explain control unit 110. CPU (Central Processing Unit) 191 executes various processes using computer programs and data stored in RAM 192. In this way, CPU 191 controls the overall operation of motor control device 100, and also executes or controls various processes that will be explained as processes performed by motor control device 100.

[0017] RAM (Random Access Memory) 192 has an area for storing computer programs and data loaded from ROM 193, and a work area used when CPU 191 executes various processes. In this way, RAM 192 can provide various areas as needed.

[0018] ROM (Read Only Memory) 193 stores setting data for motor control device 100, computer programs and data related to the startup of motor control device 100, computer programs and data related to the basic operation of motor control device 100, and the like.

[0019] The rotational position detection unit 111 detects the rotation angle of the rotor of the motor 101 based on the pulses output from the angle sensor 102. If the number of pulses output from the angle sensor 102 during one rotation of the rotor is N, then the number of rising edges and falling edges of the pulses detected by the angle sensor 102 during one rotation of the rotor is 4N. Therefore, the mechanical angle θm through which the rotating shaft (rotor) of the motor 101 rotates is expressed by the following equation (1) using the number of pole pairs P of the motor 101.

[0020] θm=Px360 / (4xN) (1) Here, θm corresponds to the mechanical angle of the rotating shaft (rotor) of the motor 101, and the angle obtained by dividing θm by the number of pole pairs P corresponds to the electrical angle of the motor 101. Furthermore, the number of pole pairs P is a value specific to the motor being used, and the number of pulses N is a value specific to the rotary encoder being used. The mechanical angle θm is stored in RAM 192 of the control unit 110. The rotational position detection unit 111 calculates the rotational phase θ of the rotor based on the number m of detected edges, using the following equation (2).

[0021] θ=θ0+mxPx360 / (4xN) (2) Here, θ0 is the rotational phase (initial phase) of the rotor when driving of the motor 101 starts. The position servo 112 calculates dq-axis current command values ​​(q-axis current command value and d-axis current command value) from the input / set "target rotation angle of the rotor" and the "current rotation angle of the rotor calculated by the rotational position detection unit 111." The position servo 112 calculates the dq-axis current command values ​​based on feedback control such as PID control so that the deviation between the "target rotation angle of the rotor" and the "current rotation angle of the rotor" becomes zero. Note that a permanent magnet is used in the rotor of the motor 101, and the d-axis current command value, which affects the strength of the magnetic flux penetrating the windings, is usually set to zero.

[0022] The current servo 113 generates drive voltages VdVq (drive voltages Vd and Vq) in the rotating coordinate system based on the dq-axis current command values ​​calculated by the position servo 112 and the dq-axis current current values ​​calculated by the second coordinate transformation unit 117.

[0023] The first coordinate conversion unit 114 inversely converts the drive voltages Vq and Vd in the rotating coordinate system generated by the current servo 113 into drive voltages Vu, Vv, and Vw in the stationary coordinate system. The PWM signal generation unit 115 generates a PWM control signal based on the drive voltages obtained by the inverse conversion by the first coordinate conversion unit 114, and outputs the generated PWM control signal to the inverter 104. As a result, the inverter 104 drives the motor 101 by supplying a drive current corresponding to the drive voltage to the windings of each phase of the motor 101.

[0024] The current detection unit 116 is an A / D converter that detects the drive current flowing through the windings of the motor 101. The second coordinate conversion unit 117 converts the drive currents iu, iv, and iw in the stationary coordinate system detected by the current detection unit 116 into drive currents iq and id (current d- and q-axis current values) in the rotating coordinate system.

[0025] The initial phase determination unit 118 sets dq-axis current command values ​​for the current servo 113 so as to determine the rotor rotation phase (initial phase) when the motor 101 starts to be driven. Specifically, the initial phase determination unit 118 sets dq-axis current command values ​​so as to generate a current vector in the direction of the stator that is desired to be attracted. As a result, the rotor is attracted to the magnetic flux resulting from the current supplied to the stator winding, and the rotor rotation phase can be determined as the initial phase. The initial phase determination unit 118 also controls the rotor rotation angle used in the calculations in the first coordinate transformation unit 114 and the second coordinate transformation unit 117, thereby controlling the direction in which the current vector is generated.

[0026] An example configuration of the motor 101 will now be described using the schematic diagram of FIG. 2. The motor 101 has a stator 210 and a rotor 220. The stator 210 has multiple stator poles 211, each with a winding wound around an iron core of the stator 210, and has six slots (magnetic poles). The windings of opposing stator poles 211 are connected in series to form one phase, each consisting of a UVW three-phase winding. The rotor 220 has permanent magnets 221 and is disposed on the inner periphery of the stator 210. FIG. 2 shows an example in which the number of magnetic poles is four, i.e., the number of pole pairs is two. The number of magnetic poles of the stator 210 and rotor 220 is not limited to this and can be freely selected. The stator poles 211 can attract the permanent magnets 221 by magnetic flux resulting from current supplied to the windings of the stator 210. For example, by making the stator magnetic pole 211 an S pole, it is possible to attract the N pole of the permanent magnet 221. Furthermore, the polarity (N pole, S pole) can be changed depending on the direction of the current in the winding. The stator magnetic pole 211 marked as U phase is set to 0°, which is the reference position, and the rotation phase of the rotor 220 is determined by the rotation angle from there. The clockwise direction of the rotor 220 is set to the positive direction. The angle of the rotor 220 is detected by the angle sensor 102.

[0027] Next, the relationship between the phases of the stator 210 and the angle of the rotor 220 will be described with reference to FIG. 3. The three-phase windings of U, V, and W are arranged at intervals of 120° electrical angle, and a three-phase (U, V, W) stationary coordinate system is defined based on this. Here, the electrical angle refers to the angle obtained by multiplying the rotation angle of the rotor 220, which is a mechanical angle, by the number of magnetic poles of the rotor 220. In other words, when the three phases of U, V, and W are formed at intervals of 60° mechanical angle, the intervals in electrical angle are 120°. A two-phase (d, q) rotating coordinate system is defined, with the d-axis being the magnetic flux direction (north pole direction) of the permanent magnet 221 of the rotor 220, i.e., the rotation phase Δθ of the rotor 220 in electrical angle, and the q-axis being rotated 90° electrical angle in the positive direction from the d-axis. Specifically, a three-phase (U, V, W) stationary coordinate system and a two-phase (d, q) rotating coordinate system can be mutually converted based on the rotational phase Δθ of rotor 220 in electrical angle by processing by first coordinate conversion unit 114 and processing by second coordinate conversion unit 117. Specifically, second coordinate conversion unit 117 converts from the three-phase (U, V, W) stationary coordinate system to the two-phase (d, q) rotating coordinate system, and the conversion equation is expressed by the following equation (3).

[0028]

number

[0029] where θ is the rotational phase of the rotor in electrical angle. Similarly, the first coordinate converter 114 converts from the two-phase (d, q) rotating coordinate system to the three-phase (U, V, W) stationary coordinate system, and the conversion formula is expressed by the following formula (4) (although the conversion formula for current is shown here, the conversion for voltage is also performed using an equivalent conversion formula).

[0030]

number

[0031] Here, θ is the rotational phase of the rotor in electrical angle. Next, a method for generating a current vector in determining the initial phase of the rotor of the motor 101 will be described with reference to Fig. 4. Fig. 4(a) shows a method for generating a current vector in a 90° clockwise direction, with the U phase as the reference 0°, in a three-phase (U, V, W) stationary coordinate system.

[0032] The initial phase determination unit 118 controls the direction of the generated current vector by controlling the rotation phase of the rotor used in the coordinate transformation, which is the calculation performed by the first coordinate transformation unit 114 and the second coordinate transformation unit 117.

[0033] The initial phase determination unit 118 sets a dq-axis current command value 401 for the current servo 113. The q-axis current command value in the dq-axis current command value 401 is set to 0, and the d-axis current command value in the dq-axis current command value 401 is set to an arbitrary current value determined based on the configuration of the motor 101 and the load 105. The initial phase determination unit 118 sets the rotor rotation phase Δθ used in the coordinate transformation in the first coordinate transformation unit 114 and the second coordinate transformation unit 117 to 90°.

[0034] The first coordinate transformation unit 114 converts the dq-axis current command value 401 into current vectors (U-phase current vector 402, V-phase current vector 403, and W-phase current vector 404) in a three-phase (U, V, W) stationary coordinate system by setting the rotational phase Δθ to θ in the above equation (4) and performing the calculation of equation (4). The first coordinate transformation unit 114 then generates a resultant vector 405, which is a vector obtained by combining the U-phase current vector 402, the V-phase current vector 403, and the W-phase current vector 404. The resultant vector 405 is a current vector generated in a 90° clockwise direction with the U phase as the reference 0°, and coincides with the rotational phase Δθ set by the initial phase determination unit 118. The resultant vector 405 acts to pull the rotor of the motor 101 in the direction of the rotational phase Δθ, i.e., the 90° electrical angle.

[0035] Fig. 4(b) shows a method for generating a current vector in a three-phase (U, V, W) stationary coordinate system in a direction of 0° clockwise, with the U phase as the reference 0°. Explanation of the same content as that explained using Fig. 4(a) will be omitted.

[0036] The initial phase determination unit 118 sets a dq-axis current command value 411 for the current servo 113, and also sets the rotor rotation phase Δθ used in the coordinate transformation in the first coordinate transformation unit 114 and the second coordinate transformation unit 117 to 0°.

[0037] The first coordinate transformation unit 114 sets the rotational phase Δθ to θ in the above equation (4) and performs the calculation of equation (4), thereby transforming the dq-axis current command value 411 into a U-phase current vector 412, a V-phase current vector 413, and a W-phase current vector 414. The first coordinate transformation unit 114 then generates a resultant vector 415, which is a vector obtained by combining the U-phase current vector 412, the V-phase current vector 413, and the W-phase current vector 414. The resultant vector 415 acts to pull the rotor of the motor 101 in the direction of the rotational phase Δθ in terms of electrical angle, i.e., in the direction of 0°.

[0038] Figure 4(c) shows a method for generating a current vector in a three-phase (U, V, W) stationary coordinate system, with the U phase as the reference 0° and in the direction of 90° counterclockwise, i.e., -90°. The details explained using Figure 4(a) will be omitted.

[0039] The initial phase determination unit 118 sets a dq-axis current command value 421 for the current servo 113, and also sets the rotor rotation phase Δθ used in the coordinate transformation in the first coordinate transformation unit 114 and the second coordinate transformation unit 117 to −90°.

[0040] The first coordinate transformation unit 114 sets the rotational phase Δθ to θ in the above equation (4) and performs the calculation of equation (4), thereby transforming the dq-axis current command value 421 into a U-phase current vector 422, a V-phase current vector 423, and a W-phase current vector 424. The first coordinate transformation unit 114 then generates a resultant vector 425, which is a vector obtained by combining the U-phase current vector 422, the V-phase current vector 423, and the W-phase current vector 424. The resultant vector 425 acts to pull the rotor of the motor 101 in the direction of the rotational phase Δθ in terms of electrical angle, i.e., in the direction of −90°.

[0041] Figure 4(d) shows a method for generating a current vector in a three-phase (U, V, W) stationary coordinate system in a direction of 180° clockwise, with the U phase as the reference 0°. The details explained using Figure 4(a) will be omitted.

[0042] The initial phase determination unit 118 sets a dq-axis current command value 431 for the current servo 113, and also sets the rotor rotation phase Δθ used in the coordinate transformation in the first coordinate transformation unit 114 and the second coordinate transformation unit 117 to 180°.

[0043] The first coordinate transformation unit 114 sets the rotational phase Δθ to θ in the above equation (4) and performs the calculation of equation (4), thereby transforming the dq-axis current command value 431 into a U-phase current vector 432, a V-phase current vector 433, and a W-phase current vector 434. The first coordinate transformation unit 114 then generates a resultant vector 435, which is a vector obtained by combining the U-phase current vector 432, the V-phase current vector 433, and the W-phase current vector 434. The resultant vector 435 acts to pull the rotor of the motor 101 in the direction of the rotational phase information Δθ in terms of electrical angle, i.e., in the direction of 180°.

[0044] As described above, the initial phase determination unit 118 sets the rotational phase Δθ, which is the same angle as the direction in which the rotor of the motor 101 is desired to be pulled, in the first coordinate transformation unit 114 and the second coordinate transformation unit 117, and sets the d-axis to an arbitrary current value and the q-axis to 0 in the dq-axis current command value in the current servo 113, thereby making it possible to generate a current vector that acts to pull the rotor to the desired angle.

[0045] The process performed by the motor control device 100 to determine the initial phase of the rotor of the motor 101 will be described with reference to the flowchart in Fig. 5. The process according to the flowchart in Fig. 5 is executed, for example, when the motor control device 100 starts to control the motor 101.

[0046] In step S501, the initial phase determination unit 118 sets the rotational phase Δθ used in the coordinate transformation in the first coordinate transformation unit 114 and the second coordinate transformation unit 117 to 90°. The initial phase determination unit 118 also sets, for the current servo 113, a d-axis current command value set to an arbitrary current value determined based on the configuration of the motor 101 and the load 105, and a q-axis current command value set to 0.

[0047] The first coordinate transformation unit 114 converts the dq-axis current command value into a current vector (U-phase current vector, V-phase current vector, W-phase current vector) in a three-phase (U, V, W) stationary coordinate system by setting the rotational phase Δθ=90 to θ in the above equation (4) and performing the calculation of equation (4).The first coordinate transformation unit 114 then generates a composite vector by combining the U-phase current vector, V-phase current vector, and W-phase current vector.

[0048] Since this resultant vector is a current vector that acts to pull the rotor of motor 101 in a direction of an electrical angle of 90°, motor control device 100 operates based on this current vector to pull the rotor of motor 101 in a direction of an electrical angle of 90°, and rotational position detection unit 111 detects the rotational angle of the rotor.

[0049] In step S502, the initial phase determination unit 118 sets the rotational phase Δθ used in the coordinate transformation in the first coordinate transformation unit 114 and the second coordinate transformation unit 117 to 0°. The initial phase determination unit 118 also sets, for the current servo 113, a d-axis current command value set to an arbitrary current value determined based on the configuration of the motor 101 and the load 105, and a q-axis current command value set to 0.

[0050] The first coordinate transformation unit 114 converts the dq-axis current command value into a current vector (U-phase current vector, V-phase current vector, W-phase current vector) in a three-phase (U, V, W) stationary coordinate system by setting the rotational phase Δθ=0 to θ in the above equation (4) and performing the calculation of equation (4).The first coordinate transformation unit 114 then generates a composite vector by combining the U-phase current vector, V-phase current vector, and W-phase current vector.

[0051] Since this resultant vector is a current vector that acts to pull the rotor of motor 101 in the direction of an electrical angle of 0°, motor control device 100 operates based on this current vector to pull the rotor of motor 101 in the direction of an electrical angle of 0°, and rotational position detection unit 111 detects the rotational angle of the rotor.

[0052] In step S503, the initial phase determination unit 118 determines whether the amount of change from the "rotation angle detected by the rotation position detection unit 111 in step S501" to the "rotation angle detected by the rotation position detection unit 111 in step S502" is equal to or less than a threshold value (for example, a specified value of 0). If the result of this determination is that the amount of change is equal to or less than the threshold value (equal to or less than the specified value), the process proceeds to step S504, and if the amount of change is greater than the threshold value, the process proceeds to step S507.

[0053] In step S504, the initial phase determination unit 118 sets the rotation phase used in the coordinate transformation in the first coordinate transformation unit 114 and the second coordinate transformation unit 117 to −90°. The initial phase determination unit 118 also sets, for the current servo 113, a d-axis current command value set to an arbitrary current value determined based on the configuration of the motor 101 and the load 105, and a q-axis current command value set to 0.

[0054] The first coordinate transformation unit 114 converts the dq-axis current command value into a current vector (U-phase current vector, V-phase current vector, W-phase current vector) in a three-phase (U, V, W) stationary coordinate system by setting the rotational phase Δθ=−90 to θ in the above equation (4) and performing the calculation of equation (4).The first coordinate transformation unit 114 then generates a composite vector by combining the U-phase current vector, V-phase current vector, and W-phase current vector.

[0055] Since this resultant vector is a current vector that acts to pull the rotor of motor 101 in the direction of an electrical angle of -90°, motor control device 100 operates based on this current vector to pull the rotor of motor 101 in the direction of an electrical angle of -90°, and rotational position detection unit 111 detects the rotational angle of the rotor.

[0056] In step S505, the initial phase determination unit 118 determines whether the amount of change from the "rotation angle detected by the rotation position detection unit 111 in step S501" or the "rotation angle detected by the rotation position detection unit 111 in step S502" to the "rotation angle detected by the rotation position detection unit 111 in step S504" is equal to or less than a threshold value (for example, 0). If the result of this determination shows that the amount of change is equal to or less than the threshold value, the process proceeds to step S506, and if the amount of change is greater than the threshold value, the process proceeds to step S507.

[0057] In step S506, the initial phase determination unit 118 sets the rotation phase used in the coordinate transformation in the first coordinate transformation unit 114 and the second coordinate transformation unit 117 to 180°. The initial phase determination unit 118 also sets, for the current servo 113, a d-axis current command value set to an arbitrary current value determined based on the configuration of the motor 101 and the load 105, and a q-axis current command value set to 0.

[0058] The first coordinate transformation unit 114 converts the dq-axis current command value into a current vector (U-phase current vector, V-phase current vector, W-phase current vector) in a three-phase (U, V, W) stationary coordinate system by setting the rotational phase Δθ=180 to θ in the above equation (4) and performing the calculation of equation (4).The first coordinate transformation unit 114 then generates a composite vector by combining the U-phase current vector, V-phase current vector, and W-phase current vector.

[0059] Since this resultant vector is a current vector that acts to pull the rotor of motor 101 in a direction of 180° electrical angle, motor control device 100 operates based on this current vector to pull the rotor of motor 101 in a direction of 180° electrical angle, and rotational position detection unit 111 detects the rotational angle of the rotor.

[0060] In step S507, initial phase determination unit 118 determines the initial phase of the rotor. When the process proceeds from step S503 to step S507, the rotational phase set by initial phase determination unit 118 is 0°, so initial phase determination unit 118 determines that the initial phase is 0°. On the other hand, when the process proceeds from step S505 to step S507, initial phase determination unit 118 determines that the initial phase of the rotor is -90°. When the process proceeds from step S506 to step S507, initial phase determination unit 118 determines that the initial phase of the rotor is 180°.

[0061] By this processing, if the amount of change is below a threshold, it is detected as a failure of the retraction operation due to hitting the end of the mechanism, and by changing the direction of the current vector to change the retraction direction, even if rotation in a specific direction is not possible due to the influence of the end of the mechanism, etc., the rotor can be successfully retracted and the initial phase can be determined.

[0062] In the above description, the d-axis current command value set by the initial phase determination unit 118 may be a fixed value or may be a value that changes over time. If it changes over time, a period in which the d-axis current command value is increased and a period in which the d-axis current command value is not changed may be provided, and the d-axis current command value may be changed by measuring each period using a timer unit of the CPU 191.

[0063] The threshold values ​​used in steps S503 and S505 may be 0 or may be appropriately set depending on the configurations of the motor 101 and the load 105. For example, if the rotation angle detected by the rotational position detection unit 111 changes due to the motor 101 biting into or riding over the mechanical end when the motor is driven toward the mechanical end in order to determine the initial phase, this may be used as the threshold value. Alternatively, the determination may be made based on whether the amount of change in the rotational angle detected by the rotational position detection unit 111 reaches a desired amount of change. For example, in step S503, it is assumed that the rotor of the motor 101 will rotate by −90° electrical angle in step S502. Therefore, if the amount of change in the rotational angle detected by the rotational position detection unit 111 is −90° electrical angle, control may be performed to transition to step S507. Similarly, in step S505, it is assumed that the rotor of the motor 101 will rotate by 90° or −90° electrical angle in step S504. Therefore, when the amount of change in the rotation angle detected by the rotation position detection unit 111 is −45° or 45° in electrical angle, control may be performed so as to transition to step S507.

[0064] That is, in this embodiment, the initial phase of the rotor of the motor 101 is determined based on whether the amount of change in the rotational phase of the rotor detected before and after control of the rotational phase of the rotor is equal to or less than a threshold value.

[0065] 6 is an explanatory diagram of an example of failure in initial phase determination due to hitting the end of the mechanism. In Fig. 6, the same parts as in Fig. 2 are given the same reference numerals, and the description of these parts will be omitted.

[0066] The motor 101 is connected to the load 105. The mechanical end 601 is a mechanical end provided on the load 105. FIG. 6 shows a state in which the mechanical end 601 hits, preventing the rotor 220 of the motor 101 from rotating counterclockwise. The current vector 602 is a current vector generated for the initial phase determination operation that acts to attract the rotor 220 toward the U-phase. The arrow 603 indicating the direction of the rotor's magnetic poles indicates the direction of the rotor 220, showing a state in which the rotor 220 has rotated 45° clockwise with the U-phase being the reference angle of 0°. When the current vector 602 corresponds to the arrow 603 (the direction of the rotor's magnetic poles), the rotor 220 is rotated counterclockwise and pulled in. However, the mechanical end 601 prevents the rotor 220 from rotating counterclockwise, resulting in a failed pull-in. This results in a phase shift θ1 between the current vector 602 and the arrow 603.

[0067] Figure 7 shows the effect of a phase shift θ1 on vector control. Figure 7(a) shows a three-phase (U, V, W) stationary coordinate system for vector control, in which the rotor phase is controlled by the current values ​​iu, iw, and iv for each axis. Figure 7(a) shows a state in which the phase shift θ1 described in Figure 6 causes a phase shift of θ2 (the angle obtained by dividing the phase shift θ1 by the number of pole pairs) in electrical angle terms. Figure 7(b) shows a two-phase (d, q) rotating coordinate system for vector control, in which the current value iq of the q-axis component (torque current component) that generates torque in the rotor and the current value id of the d-axis component (excitation current component) that affects the strength of the magnetic flux penetrating the winding are used. The d'-axis and q'-axis represent coordinate axes that are offset by the phase shift θ2 from the dq-axis, which is determined by the actual rotor phase. The three-phase (U, V, W) stationary coordinate system and the two-phase (d, q) rotating coordinate system are mutually converted by the first coordinate converter 114 and the second coordinate converter 117 based on the rotor rotation phase Δθ in electrical angle. If the three-phase (U, V, W) stationary coordinate system shown in FIG. 7(a) is shifted by θ2, the coordinate system is transformed to the d'- and q'-axes shown in FIG. 7(b). In the d'- and q'-axes coordinate system, the d'-axis component current value i' and the q'-axis component current value i' are not independent components because they are shifted by Δθ from the true d- and q-axes. In this case, controlling i' affects the d-axis current value, which may cause problems such as unstable control due to torque changes and increased power consumption. Furthermore, if Δθ is 180°, the rotor rotation direction corresponding to the i'q' current direction is reversed, potentially resulting in reverse running. For this reason, the initial phase determination unit 118 must perform control so that the rotor pull-in during initial phase determination does not fail due to factors such as hitting the end of the mechanism. The following table shows the behavior during pull-in depending on the state at the start of initial phase determination.

[0068] [Table 1]

[0069] The leftmost column of the table shows the magnetic pole orientation of the rotor of motor 101 at the start of initial phasing. The magnetic pole orientation of the rotor of motor 101 at the start of initial phasing is divided into mechanical angles of 0°, 45°, 90°, and -45°, or electrical angles of 0°, 90°, 180°, and -90°. Because the number of magnetic poles on the rotor of motor 101 is four, i.e., the number of pole pairs is two, the division into mechanical angles with the same electrical angle is omitted. A diagram showing a schematic representation of the orientation of the rotor of motor 101 at this time is included, with the upward direction of the table being the U-phase direction of the stator of motor 101, and the magnetic pole orientation is shown when this is set to the reference position of 0°.

[0070] The second column from the left of the table distinguishes between cases where the rotor of motor 101 cannot rotate clockwise or counterclockwise due to the end of the mechanism attached to load 105 hitting the end at the start of initial phase determination, and cases where it can rotate both clockwise and counterclockwise. "None" indicates a case where it can rotate in both directions, CW indicates a case where the rotor of motor 101 cannot move clockwise due to the end of the mechanism hitting the end in the clockwise direction, and CCW indicates a case where the rotor of motor 101 cannot move counterclockwise due to the end of the mechanism hitting the end in the counterclockwise direction.

[0071] The third, fourth, fifth, and sixth columns from the left in the table correspond to the processing in step S501, the processing in step S502, the processing in steps S503 and S504, and the processing in steps S505 and S506, respectively. For the sake of explanation, the direction of generation of the current vectors in the table is expressed in mechanical angles, but when expressed as electrical angles, it coincides with the direction of generation of each current vector described with reference to FIG.

[0072] The values ​​in the table are the angle reached by the rotor of motor 101 after completion of each process (processes 1 to 4) in the third, fourth, fifth, and sixth columns from the left of the table, and the angle traveled to reach that angle, each expressed in mechanical angle.

[0073] Looking at the table for the cases where "None" is displayed in the second column from the left, we can see that after process 2 is completed, the rotor reaches a mechanical angle equivalent to 0°. Furthermore, when process 2 is executed, the rotor rotates at a mechanical angle equivalent to 45°. In other words, in the process of step S502, which corresponds to process 2, a current vector is generated in the 0° direction, successfully pulling the rotor to an electrical angle of 0°. Furthermore, in the next process, step S503, the amount of change in the rotation angle is not below the threshold (not 0), so the process proceeds to step S507, where the initial phase can be determined to be an electrical angle of 0°. There are four cases in which pulling in the initial phase in processes 1 and 2 fails.

[0074] The first pattern is 0° in the leftmost column of the table and CW in the second column from the left; the second pattern is 45° in the leftmost column of the table and CCW in the second column from the left; the third pattern is 90° in the leftmost column of the table and CCW in the second column from the left; and the fourth pattern is -45° in the leftmost column of the table and CW in the second column from the left. In all of the first through fourth patterns, the drive direction is limited by the end of the mechanism, so processes 1 and 2 are unable to pull the rotation in the direction of the current vector generation, resulting in a movement amount of 0. In other words, the change in the rotation angle is 0. In this case, process 3 is executed from the third column from the left of the table onwards. Process 3 specifically corresponds to the processes of steps S503 and S504. In step S503, the change in the rotation angle is equal to or less than the threshold (0), so the process of step S504 generates a current vector in the direction of a mechanical angle of -45°, i.e., in the direction of an electrical angle of -90°. At this time, only patterns 1 and 3 are capable of retracting the current vector in the direction of an electrical angle of -90°. In the case of pattern 1, retraction is successful after rotation in the direction of a mechanical angle of -45°, and in the case of pattern 3, retraction is successful after rotation in the direction of a mechanical angle of 45°. On the other hand, in patterns 2 and 4, the drive direction is limited by the end of the mechanism, so retraction in the direction in which the current vector is generated is not possible, and the movement amount is 0. In other words, the change in the rotation angle is 0. In this case, process 4 is executed. Process 4 specifically corresponds to the processes of steps S505 and S506. In step S505, the change in the rotation angle is equal to or less than the threshold (0), so in step S506, a current vector is generated in the direction of a mechanical angle of 90°, i.e., an electrical angle of 180°. At this time, patterns 2 and 4 are the only patterns that can be pulled in to a direction equivalent to an electrical angle of 180°. In the case of pattern 2, the pull-in is successful when the rotation is in the direction of a mechanical angle of 45°, and in the case of pattern 4, the pull-in is successful when the rotation is in the direction of a mechanical angle of -45°.

[0075] By performing the above steps 1 to 4, the initial phase determination pull-in operation is successful regardless of the magnetic pole orientation at the start of initial phase determination or the drive direction limitation by the mechanical end. Furthermore, when performing steps 1 to 4, the rotation direction closest to collision with the mechanical end can be determined by which step succeeded in pull-in and the direction of drive when pull-in was successful. Specifically, if pull-in is successful by step 3, in the case of pattern 1, pull-in is successful when rotating in the -45° mechanical angle direction, and in the case of pattern 3, pull-in is successful when rotating in the 45° mechanical angle direction. This indicates that the former will collide with the mechanical end if rotating clockwise, and the latter will collide with the mechanical end if rotating counterclockwise. Similarly, if pull-in is successful by step 4, in the case of pattern 2, pull-in is successful when rotating in the 45° mechanical angle direction, and in the case of pattern 4, pull-in is successful when rotating in the -45° mechanical angle direction. This indicates that the former will collide with the mechanical end if rotating counterclockwise. The latter will collide with the end of the mechanism if it rotates counterclockwise. After the initial phase determination is completed, when the control unit 110 receives a drive command from the operation unit 103, the control unit 110 may suppress the drive command in the direction of the end of the mechanism detected by the above method to prevent the latter from colliding with the end of the mechanism again.

[0076] In this way, according to this embodiment, it is possible to provide a motor control device that can control the initial phase setting so that the rotor is pulled in the desired direction even when it cannot rotate in a specific direction due to the influence of the mechanical ends or the like.

[0077] 1, the functional units other than the CPU 191, RAM 192, ROM 193, and current detection unit 116 may be implemented by hardware or software (computer programs). In the latter case, such computer programs are stored in ROM 193, and the CPU 191 reads the computer programs into RAM 192 and executes them to realize the functions of the corresponding functional units.

[0078] [Second embodiment] In each of the following embodiments, including this embodiment, differences from the first embodiment will be described, and unless otherwise specified below, they will be considered to be the same as the first embodiment. In this embodiment, a case will be described in which the motor control device 100 is applied to a camera-head imaging system. An example of the appearance of the camera-head imaging system 800 is shown in FIG. 8. The camera-head imaging system 800 has a camera-head device 801 and an imaging device 802.

[0079] The camera platform device 801 has a mechanism for rotatably holding the imaging device 802, and is also provided with a pan drive unit 803 for controlling the attitude of the imaging device 802 in the pan direction, and a tilt drive unit 804 for controlling the attitude of the imaging device 802 in the tilt direction. The pan drive unit 803 and the tilt drive unit 804 are provided with the motor control device 100 as a power source.

[0080] The imaging device 802 is an imaging device that captures still images periodically or irregularly, or an imaging device that captures moving images. The attitude of the imaging device 802 can be changed by a pan driving unit 803 and a tilt driving unit 804, thereby controlling the imaging direction of the imaging device 802.

[0081] The pan drive unit 803 is provided with a mechanical end that limits the range of movement, and is configured to drive within a range of 180° in both the clockwise and counterclockwise directions, with the front direction (the direction shown in the figure) being 0°. When the pan drive unit 803 drives in the clockwise direction, the motor control device 100 rotates in the clockwise direction, and when the pan drive unit 803 drives in the counterclockwise direction, the motor control device 100 drives in the counterclockwise direction.

[0082] Tilt drive unit 804 is provided with a mechanical end that limits the range of motion, and is configured to drive within a range of 40° in both the up and down directions, with the front direction (the direction shown in the figure) being 0°. When tilt drive unit 804 drives upward, motor control device 100 rotates clockwise, and when tilt drive unit 804 drives downward, motor control device 100 drives counterclockwise.

[0083] When the pan drive unit 803 and tilt drive unit 804 reach positions of 180° and 40°, respectively, they collide with the end of the mechanism. At that time, the motor control device 100 is unable to rotate in either the clockwise or counterclockwise direction. By performing the control shown in the first embodiment with the motor control device 100, even if rotation in a specific direction is not possible due to the influence of the end of the mechanism or the like, it is possible to perform initial phase determination control to pull the rotor in the desired direction, and motor control can be started.

[0084] [Third embodiment] In this embodiment, a case will be described in which the motor control device 100 is applied to a lens unit. As shown in FIG.

[0085] The lens 901 is an imaging or projection optical system, and is a projection or imaging optical system composed of multiple lenses including a focus adjustment group. Driving the focus adjustment group enables focus adjustment, which moves the focus position (image plane) of a captured or projected image along the optical axis of the lens 901. The image plane has a certain depth (depth of field), and if the subject and screen are within this range, a sufficiently focused image can be obtained. This allows the focus state of the captured or projected image to be adjusted, allowing for the capture and display of a captured or projected image without blur. The focus adjustment group is a lens group composed of one or more lenses. The lens group is connected to the motor control device 100, which functions as a drive device for driving the lens group. The lens group has a mechanical end that limits its movable range. When the lens group reaches the close end or telephoto end, it hits the mechanical end, and the motor control device 100 is unable to rotate either clockwise or counterclockwise due to the mechanical end. By performing the control shown in the first embodiment using the motor control device 100, even if rotation in a specific direction is not possible due to the influence of the mechanical end or the like, initial phase determination control can be performed to pull the rotor in the desired direction, and motor control can be started.

[0086] [Fourth embodiment] In this embodiment, a case will be described in which the motor control device 100 is applied to an image projection device. As shown in Figure 10, the image projection device 1000 has a projection lens 1001, a lens shift mechanism 1002, a light source unit 1003, an image forming unit 1004, and the motor control device 100.

[0087] The projection lens 1001 is a projection optical system composed of multiple lenses including a focus adjustment group. The projection lens 1001 projects an image (projected image) onto the screen by focusing light (image) modulated by the light modulation panel. The projection lens 1001 may be replaceable, or may be an interchangeable lens unit of the image projection device 1000.

[0088] The lens shift mechanism 1002 is a part of the image projection device 1000 where the projection lens 1001 is attached, and is a mechanism that shifts the projection lens 1001 attached to this part in a shift direction perpendicular to the optical axis of the projection lens 1001 relative to the light modulation panel. By shifting the projection lens including the focus adjustment group, it is possible to move the position of the projected image (projection position of image light) on the projection surface. Note that the shift direction is not limited to a direction perpendicular to the optical axis, and may be an oblique direction as long as it has a component perpendicular to the optical axis. The motor control device 100 drives the lens mount in the shift direction using the driving force of the actuator.

[0089] The light source unit 1003 includes a light source and a light source drive circuit. The light source may be any of various discharge lamps, such as a xenon lamp, a high-pressure mercury lamp, a metal halide lamp, or a halogen lamp, or may be a semiconductor light source, such as an LED (Light Emitting Diode) or a laser diode (LD). The illumination light emitted from the light source unit is guided to a light modulation panel of the image forming unit 1004 via an optical system (not shown), such as an integrator optical system or a color separation optical system.

[0090] The image forming unit 1004 forms image light by controlling the light modulation panel based on the video signal VS. The image light is projected onto a projection surface such as a screen SC via the projection optical system of the projection lens 1001. As a result, a projected image is displayed on the projection surface.

[0091] The lens shift mechanism 1002 is provided with a mechanical end that limits the movable range. When the lens shift mechanism 1002 reaches the drive range end in either direction on a plane perpendicular to the optical axis of the projection lens 1001, it hits the mechanical end, and the motor control device 100 is unable to rotate in either the clockwise or counterclockwise direction due to the mechanical end. By performing the control shown in the first embodiment with the motor control device 100, even if rotation in a specific direction is not possible due to the influence of the mechanical end or the like, it is possible to perform initial phase determination control to pull the rotor in the desired direction, and motor control can be started.

[0092] [Fifth embodiment] In this embodiment, a case will be described in which the motor control device 100 is applied to a robot arm. As shown in FIG. 11, a robot arm 1100 according to this embodiment includes the motor control device 100, an arm 1101, and a joint axis 1102.

[0093] The arm 1101 is configured to be capable of performing tasks such as "tightening a screw" and "grabbing a part" in assembly work. The indirect shaft 1102 drives the arm 1101 to move closer to an object. The motor control device 100 functions as a power source for driving the indirect shaft 1102.

[0094] The indirect shaft 1102 is provided with a mechanical end that limits its movable range. When the indirect shaft 1102 reaches the end of its driving range, it hits the mechanical end, and the motor control device 100 is unable to rotate in either the clockwise or counterclockwise direction due to the mechanical end. By performing the control shown in the first embodiment with the motor control device 100, even if rotation in a specific direction is not possible due to the influence of the mechanical end or the like, it is possible to perform initial phase determination control to pull the rotor in the desired direction, and motor control can be started.

[0095] As described above, in the second and subsequent embodiments, various application examples of motor control device 100 have been described, but the above application examples are merely examples. In other words, even if the motor hits the mechanical end when it reaches the end of its drive range and is therefore unable to rotate in a specific direction, motor control device 100 can be applied to a variety of cases as long as initial phase determination control is performed to pull the rotor in the desired direction.

[0096] [Sixth embodiment] In this embodiment, the motor control device 100 performs processing to determine the initial phase of the rotor of the motor 101. After performing pull-in toward an electrical angle of 90° and an electrical angle of 0°, if the encoder change amount has not changed by 90° in electrical angle, a current vector is generated in the direction of an electrical angle of 180° and an electrical angle of -90° (=270°), and the rotor is pulled in the direction of an electrical angle of -90°. Specific processing steps will be described with reference to the flowchart in FIG. 12. The processing according to the flowchart in FIG. 12 is executed, for example, when the motor control device 100 starts controlling the motor 101. Step S1201 is similar to step S501, and step S1202 is similar to step S502, so description thereof will be omitted.

[0097] In step S1203, the initial phase determination unit 118 determines whether the amount of change from the "rotation angle detected by the rotation position detection unit 111 in step S501" to the "rotation angle detected by the rotation position detection unit 111 in step S502" is a specified value of 90°. If the result of this determination is 90°, the process proceeds to step S1206, and if not, the process proceeds to step S1204.

[0098] At this time, a range may be set around 90°, such as 80° to 100°, and the determination may be made based on whether the angle is within that range. The range of values ​​may be a fixed range, or may be an adjustment value that changes for each individual motor.

[0099] In step S1204, the initial phase determination unit 118 sets the rotation phase used in the coordinate transformation in the first coordinate transformation unit 114 and the second coordinate transformation unit 117 to 180°. The initial phase determination unit 118 also sets, for the current servo 113, a d-axis current command value set to an arbitrary current value determined based on the configuration of the motor 101 and the load 105, and a q-axis current command value set to 0.

[0100] The first coordinate transformation unit 114 converts the dq-axis current command value into a current vector (U-phase current vector, V-phase current vector, W-phase current vector) in a three-phase (U, V, W) stationary coordinate system by setting the rotational phase Δθ=180 to θ in the above equation (4) and performing the calculation of equation (4).The first coordinate transformation unit 114 then generates a composite vector by combining the U-phase current vector, V-phase current vector, and W-phase current vector.

[0101] Since this resultant vector is a current vector that acts to pull the rotor of motor 101 in a direction of 180° electrical angle, motor control device 100 operates based on this current vector to pull the rotor of motor 101 in a direction of 180° electrical angle, and rotational position detection unit 111 detects the rotational angle of the rotor.

[0102] In step S1205, the initial phase determination unit 118 sets the rotation phase used in the coordinate transformation in the first coordinate transformation unit 114 and the second coordinate transformation unit 117 to −90°. The initial phase determination unit 118 also sets, for the current servo 113, a d-axis current command value set to an arbitrary current value determined based on the configuration of the motor 101 and the load 105, and a q-axis current command value set to 0.

[0103] The first coordinate transformation unit 114 converts the dq-axis current command value into a current vector (U-phase current vector, V-phase current vector, W-phase current vector) in a three-phase (U, V, W) stationary coordinate system by setting the rotational phase Δθ=−90 to θ in the above equation (4) and performing the calculation of equation (4).The first coordinate transformation unit 114 then generates a composite vector by combining the U-phase current vector, V-phase current vector, and W-phase current vector.

[0104] Since this resultant vector is a current vector that acts to pull the rotor of motor 101 in the direction of an electrical angle of -90°, motor control device 100 operates based on this current vector to pull the rotor of motor 101 in the direction of an electrical angle of -90°, and rotational position detection unit 111 detects the rotational angle of the rotor.

[0105] In step S1206, initial phase determination unit 118 determines the initial phase of the rotor. When the process proceeds from step S1203 to step S1206, the rotation phase set by initial phase determination unit 118 is 0°, so initial phase determination unit 118 determines that the initial phase is 0°. On the other hand, when the process proceeds from step S1205 to step S1206, initial phase determination unit 118 determines that the initial phase of the rotor is −90°.

[0106] By this processing, if the amount of change is outside a specified range of 90° or thereabouts, it is detected as a failure of the retraction operation due to hitting the end of the mechanism, and by changing the direction of the current vector to change the retraction direction, even if rotation in a specific direction is not possible due to the influence of the end of the mechanism, etc., the rotor can be successfully retracted and the initial phase can be determined.

[0107] The numerical values, processing timing, processing order, processing subject, data (information) configuration / acquisition method / sending destination / sending source / storage location, etc. used in the above embodiment are given as examples to provide a concrete explanation, and are not intended to be limited to these examples.

[0108] In addition, some or all of the embodiments described above may be used in appropriate combination, and some or all of the embodiments described above may be selectively used.

[0109] (Other embodiments) The present invention can also be realized by supplying a program that realizes one or more functions of the above-described embodiments to a system or device via a network or a storage medium, and having one or more processors in the computer of the system or device read and execute the program.The present invention can also be realized by a circuit (e.g., ASIC) that realizes one or more functions.

[0110] The invention of this specification includes the following control device, pan head system, lens unit, image projection device, robot arm, control method, and computer program. (Item 1) A control device comprising a determination means for determining an initial phase of a rotor based on whether a change in the rotational phase of the rotor detected before and after control of the rotational phase of the rotor of a motor is a specified value or is less than a specified value. (Item 2) The determining means determines the initial phase of the rotor to be 0° when a change amount from a first rotation phase of the rotor, which is detected after controlling the rotor so that the rotation phase of the rotor is 90°, to a second rotation phase of the rotor, which is detected after controlling the rotor so that the rotation phase of the rotor is 0°, is greater than a specified value. 2. The control device according to item 1, (Item 3) The determining means determines the initial phase of the rotor to be -90° if the amount of change from the first rotational phase to the second rotational phase is equal to or less than a specified value, or if the amount of change from the first rotational phase or the second rotational phase to a third rotational phase of the rotor, which is detected after controlling the rotational phase of the rotor to be -90°, is greater than a specified value. 3. The control device according to item 2, (Item 4) The determining means determines the initial phase of the rotor to be 180° if the amount of change from the first rotation phase or the second rotation phase to the third rotation phase is equal to or less than a specified value. 4. The control device according to item 3, (Item 5) 5. The control device according to any one of items 1 to 4, wherein the determining means sets the rotation phase of the rotor in a direction to pull in for coordinate conversion between a three-phase stationary coordinate system and a two-phase rotating coordinate system in vector control, and generates a current vector that acts to pull in the rotor in the pulling direction by setting a current value on the d-axis and a current value on the q-axis of the two-phase rotating coordinate system. (Item 6) 6. The control device according to item 5, wherein the determining means changes the d-axis current value over time. (Item 7) 2. The control device according to claim 1, wherein the determining means determines the initial phase of the rotor to be 0° when an amount of change from a first rotational phase of the rotor, detected after control is performed so that the rotational phase of the rotor is 90°, to a second rotational phase of the rotor, detected after control is performed so that the rotational phase of the rotor is 0°, is within a predetermined range. (Item 8) 8. The control device according to item 7, wherein, if an amount of change from a first rotational phase of the rotor, which is detected after controlling the rotational phase of the rotor to 90°, to a second rotational phase of the rotor, which is detected after controlling the rotational phase of the rotor to 0°, is outside a predetermined range, the determining means controls the rotational phase of the rotor to 180°, then controls the rotational phase of the rotor to -90°, and then determines the initial phase of the rotor to be -90°. (Item 9) 9. The control device according to any one of items 1 to 8, wherein the rotation phase of the rotor is detected by an incremental rotary encoder. (Item 10) An imaging device; A control device according to any one of items 1 to 9 for controlling the attitude of the imaging device in the pan direction and the attitude of the imaging device in the tilt direction. A pan head imaging system comprising: (Item 11) A lens group; a control device according to any one of items 1 to 9 for driving the lens group; A lens unit comprising: (Item 12) A projection lens; a control device according to any one of items 1 to 9 for driving a lens mount; An image projection device comprising: (Item 13) Arm and a control device according to any one of items 1 to 9 for driving a joint shaft that drives the arm to approach an object; and A robot arm comprising: (Item 14) A control method performed by a control device, A control method characterized by comprising a determination step in which the determination means of the control device determines the initial phase of the rotor based on whether the amount of change in the rotational phase of the rotor detected before and after control of the rotational phase of the rotor of the motor is a specified value or is less than or equal to the specified value. (Item 15) A computer program for causing a computer to function as each means of the control device according to any one of items 1 to 9.

[0111] The invention is not limited to the above-described embodiments, and various changes and modifications can be made without departing from the spirit and scope of the invention. Accordingly, the following claims are appended to apprise the public of the scope of the invention. [Explanation of symbols]

[0112] 100: Motor control device 101: Motor 102: Angle sensor 103: Operation unit 104: Inverter 105: Load 110: Control unit 111: Rotation position detection unit 112: Position servo 113: Current servo 114: First coordinate conversion unit 115: PWM signal generation unit 116: Current detection unit 117: Second coordinate conversion unit 118: Initial phase determination unit 191: CPU 192: RAM 193: ROM

Claims

1. A control device comprising a determination means for determining an initial phase of a rotor based on whether a change in the rotational phase of the rotor detected before and after control of the rotational phase of the rotor of a motor is a specified value or is less than a specified value.

2. The determining means determines the initial phase of the rotor to be 0° when a change amount from a first rotational phase of the rotor, which is detected after control is performed so that the rotational phase of the rotor is 90°, to a second rotational phase of the rotor, which is detected after control is performed so that the rotational phase of the rotor is 0°, is greater than a specified value.

2. The control device according to claim 1.

3. The determining means determines the initial phase of the rotor to be −90° if the amount of change from the first rotational phase to the second rotational phase is equal to or less than a specified value, or if the amount of change from the first rotational phase or the second rotational phase to a third rotational phase of the rotor, which is detected after control is performed so that the rotational phase of the rotor becomes −90°, is greater than a specified value.

3. The control device according to claim 2.

4. The determining means determines the initial phase of the rotor to be 180° if the amount of change from the first rotational phase or the second rotational phase to the third rotational phase is equal to or less than a specified value.

4. The control device according to claim 3.

5. 2. The control device according to claim 1, wherein the determining means sets the rotation phase of the rotor in a direction to pull in for coordinate conversion between a three-phase stationary coordinate system and a two-phase rotating coordinate system in vector control, and sets a d-axis current value and a q-axis current value in the two-phase rotating coordinate system, thereby generating a current vector that acts to pull in the rotor in the pulling direction.

6. 6. The control device according to claim 5, wherein the determining means changes the d-axis current value over time.

7. 2. The control device according to claim 1, wherein the determining means determines the initial phase of the rotor to be 0° when an amount of change from a first rotational phase of the rotor, detected after control is performed so that the rotational phase of the rotor is 90°, to a second rotational phase of the rotor, detected after control is performed so that the rotational phase of the rotor is 0°, is within a predetermined range.

8. 8. The control device according to claim 7, wherein, if an amount of change from a first rotational phase of the rotor, detected after controlling the rotational phase of the rotor to 90°, to a second rotational phase of the rotor, detected after controlling the rotational phase of the rotor to 0°, is outside a predetermined range, the determining means controls the rotational phase of the rotor to 180°, then controls the rotational phase of the rotor to -90°, and then determines the initial phase of the rotor to be -90°.

9. 2. The control device according to claim 1, wherein the rotation phase of the rotor is detected by an incremental rotary encoder.

10. An imaging device; a control device according to claim 1 for controlling the attitude of the imaging device in the pan direction and the attitude of the imaging device in the tilt direction; A pan head imaging system comprising:

11. A lens group; a control device according to claim 1 for driving the lens group; A lens unit comprising:

12. A projection lens; a control device according to claim 1 for driving a lens mount; An image projection device comprising:

13. Arm and the control device according to claim 1 for driving a joint shaft that drives the arm to approach an object; A robot arm comprising:

14. A control method performed by a control device, A control method characterized by comprising a determination step in which the determination means of the control device determines the initial phase of the rotor based on whether the amount of change in the rotational phase of the rotor detected before and after control of the rotational phase of the rotor of the motor is a specified value or is less than or equal to the specified value.

15. A computer program for causing a computer to function as each of the means of the control device according to any one of claims 1 to 9.

Images