JP6052971B2 - Synchronous motor control device and synchronous motor control method - Google Patents

Description

  The present invention relates to a synchronous motor control device and a synchronous motor control method.

  In recent years, it has been proposed to use a stepping motor as a synchronous motor in a closed loop as a drive motor used as a power source of an electric actuator.

  In general, in the case of a stepping motor, a fixed excitation sequence is executed regardless of the position of the rotor when the stepping motor is started. That is, the initial excitation position at the time of start-up is fixed, and excitation stable points exist every 360 ° on the electrical angle. Then, the rotor after the initial excitation moves so as to be drawn from the local point to the excitation stable point.

  In addition, stepping motors have inherent instability points. For example, in the case of a PM type (Permanent Magnet Type) stepping motor or a hybrid type (HB: Hybrid Type) stepping motor, there is an unstable point of detent torque due to the permanent magnet of the rotor.

  Further, in the case of a variable reluctance type (VR) stepping motor or an HB type stepping motor, an unstable point exists at a position where the small teeth of the stator and the rotor are shifted by 1/2 pitch. These exist without depending on the magnitude of the excitation current and the phase to be excited, and if the excitation stable point at the time of multi-phase excitation is in the same position as this unstable point, the stability is impaired.

  Further, even in a stepping motor that is driven in an open loop without providing a rotation detector in the rotor, when it is excited to an arbitrary position at the time of startup, the rotor may move there and vibrate for a minute time.

  For these problems, for example, a method for realizing a stable start-up operation, a method for making the first excitation time shorter than the second time, and an absolute encoder for detecting the electrical angle of the rotor are mounted. There have been proposed a method, a method of mounting a VR resolver for detecting an electrical angle of a rotor, detecting an absolute position per electrical angle, and performing stable initial driving. For example, Patent Document 1 and Patent Document 2 disclose such inventions.

JP 2000-37090 A JP 2003-18738 A

  However, in the conventional configuration described above, the excitation sequence is executed when the stepping motor is started, and the rotor after the initial excitation moves so as to be drawn to the excitation stable point near the local point, but the rotor position is electrically If the angle is 180 ° away from the excitation stable point and the rotation direction of the rotor accompanying excitation is the same as the rotation direction of the rotor caused by external force due to the arrangement of the stepping motor, the magnetic pole determination operation fails there's a possibility that. Specifically, when excitation is performed, the target excitation position may be exceeded by urging by angular acceleration and gravitational acceleration generated when the rotor moves.

  The present invention has been made in view of the problems, and an object of the present invention is to more reliably perform the magnetic pole determination process.

In order to achieve the object, a synchronous motor control device according to a first aspect of the present invention is a synchronous motor control device that controls a synchronous motor including a rotor and a stator winding,
Signal output means for outputting a periodic signal while switching the level according to the position of the rotor;
A first stator that is considered to face the position of the rotor within a predetermined range determined by the period of the signal output from the signal output means based on the level of the signal output from the signal output means First stator position specifying means for specifying a position;
First current supply control means for performing control for supplying a current of a stator current vector necessary for the position of the stator to face the first stator position to the stator winding;
A count value that changes according to the number of times of level switching of the signal output from the signal output means after the start of current supply control by the first current supply control means, and increases or decreases according to the rotation direction of the rotor. First count value determining means for determining whether or not a period during which the increase / decrease is not equal to or greater than the first predetermined value continues for a predetermined period
When it is determined by the first count value determining means that the period during which the increase / decrease in the count value does not exceed the first predetermined value continues for the predetermined period or longer, the increase / decrease in the count value is the first predetermined value. Second count value determining means for determining whether or not the second predetermined value is smaller than a second predetermined value;
When the second count value determining means determines that the increase / decrease in the count value is not equal to or greater than the second predetermined value, the specific stator that directly faces the first stator position to the rotor position First specific stator position specifying means for specifying the position;
The first count value corresponding to the increase / decrease number of the count value from the first stator position when the second count value determination means determines that the increase / decrease of the count value is equal to or greater than the second predetermined value. A second specific stator position specifying means for specifying the second stator position moved by the movement direction and the first movement amount as a specific stator position facing the rotor position;
It is characterized by providing.

When it is determined by the first count value determination means that a period during which the increase / decrease in the count value is not equal to or greater than the first predetermined value does not continue for the predetermined period or longer, the count value is determined from the first stator position. Third stator position specifying means for specifying the third stator position moved by the second movement direction and the second movement amount corresponding to the increase / decrease number of
Control for supplying a current of a stator current vector necessary for the position of the rotor to face the third stator position specified by the third stator position specifying means to the stator winding Second current supply control means for performing
A third count value for determining whether or not a period during which the increase or decrease in the count value does not exceed the first predetermined value after the start of current supply control by the second current supply control means continues for the predetermined period or more; A determination means;
When it is determined by the third count value determination means that the period during which the increase / decrease in the count value does not exceed the first predetermined value continues for the predetermined period or longer, the third stator position is set to the rotor. A third specific stator position specifying means for specifying the specific stator position as opposed to the position of
You may make it provide.

A first movement direction and a movement amount that specify a third movement direction and a third movement amount of the rotor for causing the position of the rotor that faces the specific stator position to face the target stator position. Specific means,
A current of a stator current vector for causing the rotor to rotate according to the third movement direction and the third movement amount of the rotor specified by the first movement direction and movement amount specifying means is Third current supply control means for controlling the supply to the stator winding;
After the start of the current supply control by the third current supply control means, a first determination is made as to whether or not the count value is less than or equal to a third predetermined value or less from the count value corresponding to the third movement amount. 4 count value judging means;
When the fourth count value determining means determines that the count value is less than or equal to the third predetermined value from the count value corresponding to the third movement amount, it is output from the signal output means. Final stator position specifying means for specifying the final stator position based on the level of the
You may make it provide.

When the fourth count value determining means determines that the count value is not an increase or decrease equal to or less than the third predetermined value from the count value corresponding to the third movement amount, it faces the specific stator position. A second moving direction that specifies a fourth moving direction and a fourth moving amount opposite to the previous moving direction of the rotor for causing the position of the rotor to face the target stator position. And a moving amount specifying means,
The third current supply control means causes the rotor to rotate in accordance with the fourth movement direction and the fourth movement amount of the rotor specified by the second movement direction and movement amount specification means. Control for supplying a current of a stator current vector for the stator winding may be performed.

In order to achieve the object, a synchronous motor control method according to a second aspect of the present invention is a synchronous motor control method by a synchronous motor control device that controls a synchronous motor including a rotor and a stator winding,
A signal output step of outputting a periodic signal while switching the level according to the position of the rotor;
A first stator that is considered to face the position of the rotor within a predetermined range determined by the period of the signal output in the signal output step based on the level of the signal output in the signal output step A first stator position specifying step for specifying a position;
A first current supply control step for performing control for supplying a current of a stator current vector necessary for the position of the stator to face the first stator position to the stator winding;
A count value that changes in accordance with the number of level switching times of the signal output in the signal output step after the start of current supply control in the first current supply control step and increases or decreases in accordance with the rotation direction of the rotor. A first count value determination step for determining whether or not a period during which the increase / decrease of the value does not exceed the first predetermined value continues for a predetermined period
When it is determined in the first count value determining step that the period during which the increase / decrease in the count value does not exceed the first predetermined value is continued for the predetermined period or longer, the increase / decrease in the count value is the first predetermined value. A second count value determination step for determining whether or not the second predetermined value is smaller than a second predetermined value,
When it is determined in the second count value determining step that the increase / decrease in the count value is not equal to or greater than the second predetermined value, the specific stator that directly faces the first stator position to the rotor position A first specific stator position identifying step for identifying a position;
When it is determined in the second count value determination step that the increase / decrease in the count value is greater than or equal to the second predetermined value, the first corresponding to the increase / decrease number in the count value from the first stator position. A second specific stator position specifying step for specifying the second stator position moved by the movement direction and the first movement amount as a specific stator position directly facing the rotor position;
It is characterized by including.

  According to the present invention, the magnetic pole determination operation can be performed more reliably.

It is a figure showing a schematic structure of an electric actuator system concerning an embodiment. It is a figure which shows the structure of the stepping motor control apparatus which concerns on embodiment. It is a figure which shows an example of the position on the electrical angle of the stator and rotor which concern on embodiment. It is a 1st flowchart which shows the magnetic pole determination process of the stepping motor control apparatus which concerns on embodiment. It is a 2nd flowchart which shows the magnetic pole determination process of the stepping motor control apparatus which concerns on embodiment. It is a 3rd flowchart which shows the magnetic pole determination process of the stepping motor control apparatus which concerns on embodiment. It is a figure which shows an example of the table of the correspondence of the specific stator position which concerns on embodiment, and the moving direction and movement amount of a rotor.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram illustrating a schematic configuration of an electric actuator system 100 according to the embodiment. An electric actuator system 100 shown in FIG. 1 includes a housing 1, a motor cover 3, a stepping motor 5, a joint member 7, a bearing member 8, a ball screw 9, a bearing member 10, a ball nut 11, a hollow rod 13, a rod 15, and an encoder 21. And a stepping motor control device 23.

  A motor cover 3 is connected to the housing 1. A stepping motor 5 is accommodated and arranged in the motor cover 3. The stepping motor 5 is a two-phase HB type stepping motor. The stepping motor 5 includes a columnar rotor 6b, a cylindrical stator 6a disposed so as to accommodate the rotor 6b at a predetermined interval, and a rotating shaft 6c connected to the rotor 6b. Consists of including. In the present embodiment, the stepping motor 5 is a two-phase HB type stepping motor, and an A-phase winding and a B-phase winding (not shown) are wound around the stator 6a as a stator winding.

  A ball screw 9 is connected to the rotating shaft 6 c of the stepping motor 5 via a joint member 7. A ball nut 11 is screwed to the ball screw 9, and a hollow rod 13 is fixed to the ball nut 11. A rod 15 is connected to the tip of the hollow rod 13. The joint member 7 is rotatably supported by bearing members 8 and 10.

  When the stepping motor 5 is driven according to the current supplied from the stepping motor control device 23, the rotor 6b and the rotating shaft 6c rotate, and the ball screw 9 further rotates, so that the rotation of the ball screw 9 regulates the rotation. The ball nut 11 is moved in the axial direction. The movement of the ball nut 11 moves the hollow rod 13 and further the rod 15 in the axial direction.

  The encoder 21 is of a magnetic type, and multipolar magnetization is applied to the outer peripheral surface or thrust direction surface of a disk-type magnet, and the magnetoresistive portion is interposed through a fine gap with respect to the multipolar magnetized portion. Magnetic detection elements such as elements are arranged opposite to each other. Then, as the magnet rotates, the change in the fine magnetic flux is detected by the magnetic detection element and output as a multi-pulse signal.

  In the present embodiment, the encoder 21 outputs two signals (first signal and second signal). The combination of the first signal and the second signal changes every time a change in the fine magnetic flux is detected, in other words, every time the stator position facing the rotor position P is switched. The encoder 21 has a combination in which the first signal is at a high level and the second signal is at a high level, the combination in which the first signal is at a low level and the second signal is at a high level, and the first signal is at a low level. The combination in which the second signal is at a low level, the combination in which the first signal is at a high level, and the second signal is at a low level are output periodically in this order. The encoder 21 is not limited to a magnetic type, and may be an optical encoder or the like.

  Further, the stepping motor 5 is configured to be controlled by a stepping motor control device 23. That is, the stepping motor control device 23 controls the stepping motor 5 based on a detection signal (encoder signal) from the encoder 21 and a command signal input separately. Further, the stepping motor control device 23 executes predetermined start control when the stepping motor 5 is started, thereby providing stable start characteristics.

  FIG. 2 is a diagram illustrating a configuration of the stepping motor control device 23. As shown in FIG. 2, the stepping motor control device 23 includes a control unit 102, a memory 104, a motor driver circuit 106, a current sensor 108, and an interface (I / F) unit 110.

  The control unit 102 is configured by a microcomputer, for example. The control unit 102 controls the entire stepping motor control device 23 by executing a program stored in the memory 104 and processing various data stored in the memory 104. The control unit 102 has a function of a current supply control unit 122 as a current control unit and a determination unit 124 as a determination unit. The control unit 102 connects the encoder 21 in the electric actuator. The memory 104 is, for example, a RAM (Random Access Memory) or a ROM (Read Only Memory). The memory 104 stores various information.

  The motor driver circuit 106 connects the stepping motor 5. The motor driver circuit 106 supplies current to the stepping motor 5 and controls driving of the stepping motor 5 under the control of the control unit 102. The current sensor 108 connects the stepping motor 5. The current sensor 108 acquires the value of the current flowing through the stepping motor 5 when the electric actuator system 100 is driven, in other words, when the stepping motor 5 is driven. The I / F unit 110 transmits and receives data with an external device (not shown) under the control of the control unit 102.

  Next, the control at the time of starting of the stepping motor control device 23 will be described. In this embodiment, the stepping motor 5 is an electrical angle 50 pole pair (50 electrical angles), and the resolution of the encoder 21 is 800. That is, the resolution per electrical angle (electrical angle 360 °) of the encoder 21 is 16.

  FIG. 3 is a diagram used for explaining the control at the time of starting the stepping motor control device 23, and is a diagram showing an example of the positions of the stator 6a and the rotor 6b on one electrical angle. The positions of the stator 6a and the rotor 6b are divided into 16 in the circumferential direction according to the resolution per electrical angle of the encoder 21, and the stator 6a is sequentially arranged from the position of electrical angle 0 ° in the circumferential direction. Numbers identifying the stator positions of 1 to 16 are assigned clockwise every electrical angle of 22.5 °. In addition, there are four combinations of the first signal and the second signal output from the encoder 21, and corresponding to the periodic output by repeating these four combinations, the stator positions 1 to 1 of the stator 6a. 16 is classified into four quadrants. Specifically, the stator positions 1 to 4 are the first quadrant, the stator positions 5 to 8 of the stator 6a are the second quadrant, the stator positions 9 to 12 of the stator 6a are the third quadrant, and the stator 6a. The stator positions 13 to 16 are classified into the fourth quadrant.

  In the present embodiment, when the positive phase current is supplied only to the A-phase winding and the rotor 6b is locked, the rotor position P (see FIG. 3), which is a predetermined position of the rotor 6b, is It is assumed that it faces the stator position 1 of the stator 6a corresponding to the angle 0 °.

  More specifically, in the encoder 21, when the rotor position P of the rotor 6b is directly opposed to the stator positions 1, 5, 9, and 13 of the stator 6a, the first signal is at a high level, and the second signal When the signal is output at a high level and the rotor position P of the rotor 6b faces the stator positions 2, 6, 10, and 14 of the stator 6a, the first signal is at the low level. When the combination of the two signals becomes a high level and the rotor position P of the rotor 6b faces the stator positions 3, 7, 11, and 15 of the stator 6a, the first signal is at a low level. A combination in which the second signal is at a low level is output, and the first signal is at a high level when the rotor position P of the rotor 6b faces the stator positions 4, 8, 12, 16 of the stator 6a. , The combination that the second signal becomes low level To.

  4 to 6 are flowcharts showing the magnetic pole determination process of the stepping motor control device 23. FIG. First, the determination unit 124 in the control unit 102 determines the stator position of the stator 6a that directly faces the rotor position P based on the level of the encoder signal (first signal and second signal) output from the encoder 21. Identify. As described above, there are only four combinations of the first signal and the second signal, and the repetition is performed in units of quadrants. Therefore, in which quadrant the stator position is directly opposed only by the combination of the first signal and the second signal. Until it cannot be specified. Therefore, it is assumed that the rotor position P is directly facing one of the stator positions 1 to 4 in the first quadrant of the stator 6a, and the determination unit 124 determines the first based on the level of the encoder signal. Of the stator positions 1 to 4 in the quadrant, the stator position (first stator position) that faces the rotor position P is identified (step S101).

  Specifically, the determination unit 124 specifies the first stator position as the stator position 1 when the first signal is at a high level and the second signal is at a high level, and the first signal is When the second signal is at the low level and the second signal is at the high level, the first stator position is identified as the stator position 2, the first signal is at the low level, and the second signal is at the low level. The first stator position is identified as the stator position 3, and when the first signal is at a high level and the second signal is at a low level, the first stator position is the stator position 4. Is identified.

  Next, the current supply control unit 122 outputs the current of the stator current vector necessary for the rotor position P to directly face the identified first stator position, at least one of the A-phase winding and the B-phase winding. (Step S102).

  Next, the determination unit 124 in the control unit 102 counts the number of times of switching the level of the encoder signal output from the encoder 21 after the current supply of the stator current vector in step S102 is started (step S103). In the present embodiment, the count value decreases when the rotor 6b rotates clockwise in FIG. 3, and the count value increases when it rotates counterclockwise.

  When the current supply of the stator current vector necessary for the rotor position P to directly face the first stator position in step S102 is started, the determination unit 124 is a period in which the increase / decrease of the count value is not 2 or more. Is determined for a first predetermined period or longer (step S104). Here, the first predetermined period is, for example, 150 [ms].

  When the period during which the increase / decrease in the count value is not 2 or more continues for the first predetermined period or longer (step S104: YES), the determination unit 124 determines whether the increase / decrease in the count value is 1 (step S105). ). When the increase / decrease in the count value is 1 (step S105: YES), the determination unit 124 determines whether the rotor position P and the positive value are based on the first stator position specified in step S101 and the count value in step S103. The corresponding stator position (second stator position) is specified (step S106). On the other hand, when the increase / decrease in the count value is not 1 (step S105: NO), the process of step S106 is not performed, and the process proceeds to the subsequent stage.

  In step S106, specifically, the determination unit 124 starts from the first stator position to the left when the count value after the current supply of the stator current vector in step S102 starts increasing. The stator position moved around by 1 is specified as the second stator position. Further, when the count value after the start of the current supply of the stator current vector in step S102 is in a decreasing direction, the determination unit 124 has moved the clockwise direction by 1 from the first stator position. The stator position is specified as the second stator position. For example, when the first stator position is 2 and the count value increases by 1, the determination unit 124 sets the second stator position to 1. When the first stator position is 2 and the count value is decreased by 1, the determination unit 124 sets the second stator position to 3.

  On the other hand, when the period in which the increase / decrease of the count value is not 2 or more does not continue for the first predetermined period or longer (step S104: NO), the process proceeds to the operation shown in FIG. Based on the stator position of 1 and the count value in step S103, the stator position (third stator position) facing the rotor position P is specified (step S111).

More specifically, the determination unit 124, when the count value after the current supply is started in the stator current vector in step S102 is in the increasing direction from the first stator positions, the count value clockwise The stator position that has been moved by the increment of is specified as the third stator position. The determination unit 124, when the count value after the current supply of the stator current vector in step S102 is started is in the decreasing direction from a first stator position, reduction of the count value in the counter-clockwise The stator position that has been moved only by this is specified as the third stator position. For example, when the first stator position is 2 and the count value is increased by 2, the determination unit 124 sets the third stator position to 4 . When the first stator position is 2 and the count value is decreased by 2, the determination unit 124 sets the third stator position to 16 .

  Next, the current supply control unit 122 outputs the current of the stator current vector necessary for the rotor position P to directly face the specified third stator position, at least one of the A-phase winding and the B-phase winding. (Step S112).

  Next, the determination unit 124 in the control unit 102 counts the number of times of switching the level of the encoder signal output from the encoder 21 after the current supply of the stator current vector in step S112 is started (step S113).

  When the current supply of the stator current vector necessary for the rotor position P to directly face the third stator position is started in step S112, the determination unit 124 determines a period during which the increase / decrease of the count value is not 2 or more. Is determined for a first predetermined period or longer (step S114).

  When the period in which the increase / decrease of the count value does not become 2 or more does not continue for the first predetermined period or longer (step S114: NO), the determination unit 124 determines that the number of repetitions (retry count) of the operations in steps S111 to S114 is the predetermined number of times. It is determined whether or not (for example, 10 times) has been reached (step S115). If the number of retries is greater than or equal to the predetermined number (step S115: YES), the series of operations ends. On the other hand, when the number of retries is less than the predetermined number (step S115: NO), the operations after step S111 are repeated. In the second and subsequent steps S111, the determination unit 124 replaces the first stator position with the current third stator position, and the current third stator position and the previous step S111. Based on the count value of the number of switching times of the encoder signal output from the encoder 21 after specifying the current third stator position, a new third stator position facing the rotor position P is established. Is identified.

  Further, when it is determined in step S105 that the increase / decrease in the count value is not 1 (step S105: NO), when the second stator position is specified in step S106, or in step S114, the count value is changed. When it is determined that the period during which the increase / decrease is not 2 or more has continued for the first predetermined period or longer (step S114: YES), the operation proceeds to the operation shown in FIG. Based on the specific stator position specified as being directly facing and the table shown in FIG. 7, the moving direction and moving amount of the rotor 6b for directly facing the rotor position P to the stator position 1 are specified ( Step S121).

  Here, the specific stator position is the first stator position specified in step S101 when NO is determined in step S105 of FIG. 4 and the process proceeds to step S121. In step S106 of FIG. If the second stator position is specified and the process proceeds to step S121, it is the second stator position. If YES in step S114 of FIG. 5 and the process proceeds to step S121, the process proceeds to step S111. The third stator position specified most recently.

  The table shown in FIG. 7 shows the correspondence between the specific stator position and the moving direction and moving amount of the rotor 6b. Here, the movement amount 1 corresponds to an electrical angle of 22.5 °, in other words, corresponds to a range corresponding to one stator position in the stator 6a. Further, every time the rotor 6b moves by the movement amount 1, the combination of the first signal and the second signal output from the encoder 21 changes. For example, when the specific stator position is 5, the movement amount is 12 when the rotor 6b is turned clockwise, and the movement amount is 4 when the rotor 6b is turned counterclockwise. When the shortest travel distance from the specific stator position to the stator position 1 is less than 90 ° electrical angle, the travel amount shown in FIG. 7 is 1 electrical angle (electrical angle 360 °). The amount of movement added.

  Next, the current supply control unit 122 causes the rotor 6b to rotate in accordance with the movement direction and the movement amount specified in step S121, and causes the rotor position P to face the stator position 1 in order to face the stator current. A vector current is supplied to at least one of the A-phase winding and the B-phase winding (step S122). Here, when the movement amount is 2 or more, the current supply control unit 122 supplies the current of the stator current vector to at least one of the A-phase winding and the B-phase winding while switching the current.

  Next, the determination unit 124 in the control unit 102 counts the number of times of switching the level of the encoder signal output from the encoder 21 after the current supply of the stator current vector in step S122 is started (step S123).

  Next, the determination unit 124 determines whether or not the count value is a value within plus or minus 3 of the count value corresponding to the movement amount specified in step S121 (step S124). As described above, every time the rotor 6b moves by the movement amount 1, the combination of the first signal and the second signal output from the encoder 21 changes. Therefore, the count value corresponding to the movement amount specified in step S121 is the movement amount itself specified in step S121 when the rotor 6b turns clockwise, and when the rotor 6b turns counterclockwise. This is a value obtained by multiplying the movement amount specified in step S121 by -1.

  When it is not a value within plus or minus 3 of the count value corresponding to the movement amount specified in step S121 (step S124: NO), the determination unit 124 determines that the number of repetitions (retry number) of the operations in steps S122 to S124 is a predetermined number. It is determined whether or not (for example, 10 times) has been reached (step S125). When the number of retries is equal to or greater than the predetermined number (step S125: YES), a series of operations ends. On the other hand, when the number of retries is less than the predetermined number (step S125: NO), the current supply control unit 122 is based on the specific stator position specified as facing the rotor position P and the table shown in FIG. Then, the moving direction and the moving amount of the rotor 6b for making the rotor position P directly face the stator position 1 are specified (step S126). However, the current supply control unit 122 sets the moving direction of the rotor 6b in the opposite direction to the moving direction specified immediately before. Thereafter, the operations after step S122 are repeated.

  On the other hand, when the value is within plus or minus 3 of the count value corresponding to the movement amount specified in step S121 (step S124: YES), the current supply control unit 122 switches the current of the stator current vector in step S122. The current supply in the completed state is maintained for a second predetermined period (for example, 50 [ms]) (step S127).

  Thereafter, the determination unit 124 identifies a final stator position (final stator position) that can be regarded as facing the rotor position P based on the level of the encoder signal (step S128). When the rotor position P faces the final stator position, the rotor 6b is at the final excitation excitation position.

  Specifically, considering that the rotor position P is likely to face the vicinity of the stator position 1 in the stator 6a, the determination unit 124 determines that the first signal is at a high level and the second signal Is at the high level, the final stator position is specified as the stator position 1, and when the first signal is at the low level and the second signal is at the high level, the final stator position is the stator. When the position 2 is specified and the first signal is at a high level and the second signal is at a low level, the final stator position is specified as the stator position 16. On the other hand, when the first signal is at a low level and the second signal is at a low level, the stator position 1 can be regarded as the stator position 3 or the stator position 15 separated by two movement amounts. However, since the accuracy is lacking, the determination unit 124 cannot specify.

  Next, the determination unit 124 determines whether or not the final stator position cannot be specified (step S129). If it is not unidentifiable (step S129: NO), the series of operations ends. On the other hand, if it is not possible to specify (step S129: YES), the operation after the determination in step S125 as to whether or not the number of retries has reached a predetermined number is repeated.

  If it is determined in step S105 that the increment / decrement of the count value is not 1 (step S105: NO) without performing the operations in steps S121 to S127, the second stator position is specified in step S106. If it is determined in step S114 that the period in which the increase / decrease of the count value is not 2 or more has been continued for a predetermined period or longer (step S114: YES), the operation of step S128 is performed directly. The final stator position may be specified.

  As described above, in the present embodiment, in the initial state, the stepping motor control device 23 faces the rotor position P to any one of the stator positions 1 to 4 in the first quadrant based on the encoder signal. Assuming that the stator position P is directly opposed to the assumed stator positions 1 to 4, the current of the stator current vector is supplied to at least one of the A-phase winding and the B-phase winding. . At this time, if the count value indicating the number of times of switching of the level of the encoder signal output from the encoder 21 is 0, the stepping motor control device 23 specifies the assumed stator position as the position where the rotor position P directly faces. If the count value is 1, the stator position adjacent to the assumed stator position is specified as the final position where the rotor position P directly faces.

  By performing such excitation determination processing, the movement amount (rotation amount) of the rotor during the period from the start to the end of the current supply of the stator current vector to the A-phase winding and the B-phase winding once is electrically The angle can be within 90 °. For this reason, the angular acceleration generated when the rotor 6b moves is reduced, and it is possible to prevent the target excitation position from being exceeded due to the biasing by the angular acceleration and the gravitational acceleration. In particular, when the electric actuator system is placed vertically and the movable part composed of the rod 15 and the member attached to the rod 15 can move downward in the vertical direction, the angle generated when the rotor 6b moves. If the acceleration is large, the angular acceleration and the gravitational acceleration will increase the force, and the target excitation position may be exceeded. In this embodiment, the amount of movement (rotation amount) of the rotor is set to the electric amount. Since the angular acceleration can be suppressed within an angle of 90 °, it is possible to prevent the excitation position from being exceeded, and the magnetic pole determination process can be more reliably performed.

  If the count value is 2 or more, the assumption is considered to be an error, and the stepping motor control device 23 moves the new stator position moved from the assumed stator position by the movement amount according to the count value. Is repeated, and the final position where the rotor position P directly faces is specified. For this reason, even if there is an error in the assumption, the magnetic pole determination process can be performed reliably.

  Further, after the magnetic pole determination process described above, the rotor position P is directly opposed to the stator position 1 by causing the rotor 6b to rotate at an electrical angle of 90 ° or more using a table as shown in FIG. Therefore, it is possible to determine whether or not any restraint that hinders rotation occurs in the rotor 6b. Further, when the rotor position P cannot be directly opposed to the stator position 1, the rotor 6b is rotated by an electrical angle of 90 ° or more in the opposite direction to that immediately before, so that the rotor position P Can be directly opposed to the stator position 1, so that it is possible to improve the reliability of determination as to whether or not the rotor 6 b has some kind of restraint that hinders rotation.

  Although the embodiment has been described above, the present invention is not limited to the above-described embodiment.

  In the embodiment described above, in order to determine whether or not the rotor 6b is constrained, the rotor 6b is rotated by 90 ° or more in electrical angle, but the rotation angle is not limited to this. For example, in the above-described embodiment, the second stator position shifted by 1 count back and forth in electrical angle from the first stator position is also specified as a valid stator position, in other words, the stator position. When the rotor position P directly faces the range of the maximum electrical angle of 67.5 ° in the stator 6a, the magnetic pole can be determined. In such a case, in order to determine whether or not the rotor 6b is constrained, the deviation angle allowed for the rotor 6b in determining the magnetic pole, that is, an electrical angle of 67.5 ° or more is rotated. You just have to do.

  In the embodiment, the stepping motor 5 is a two-phase HB type stepping motor. However, the present invention can be similarly applied to a VR type stepping motor, a PM type stepping motor, and the like. Further, the number of phases of the stepping motor 5 is not limited, and the present invention can be applied to various configurations such as single phase, two phase, three phase, four phase, and five phase. Moreover, it is applicable not only to a stepping motor but also to a synchronous motor such as a DC brushless motor.

  Various embodiments and modifications can be made to the present invention without departing from the broad spirit and scope of the present invention. The above-described embodiments are for explaining the present invention, and do not limit the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Housing 3 Motor cover 5 Stepping motor 6a Stator 6b Rotor 6c Rotating shaft 7 Joint member 8 Bearing member 9 Ball screw 10 Bearing member 11 Ball nut 13 Hollow rod 15 Rod 21 Encoder 23 Stepping motor control device 100 Actuator system 102 Control part 104 Memory 106 Motor driver circuit 108 Current sensor 110 I / F unit 122 Current supply control unit 124 Judgment unit

Claims (5)

A synchronous motor control device for controlling a synchronous motor including a rotor and a stator winding,
Signal output means for outputting a periodic signal while switching the level according to the position of the rotor;
A first stator that is considered to face the position of the rotor within a predetermined range determined by the period of the signal output from the signal output means based on the level of the signal output from the signal output means First stator position specifying means for specifying a position;
First current supply control means for performing control for supplying a current of a stator current vector necessary for the position of the stator to face the first stator position to the stator winding;
A count value that changes according to the number of times of level switching of the signal output from the signal output means after the start of current supply control by the first current supply control means, and increases or decreases according to the rotation direction of the rotor. First count value determining means for determining whether or not a period during which the increase / decrease is not equal to or greater than the first predetermined value has continued for a predetermined period;
When it is determined by the first count value determining means that the period during which the increase / decrease in the count value does not exceed the first predetermined value continues for the predetermined period or longer, the increase / decrease in the count value is the first predetermined value. Second count value determining means for determining whether or not the second predetermined value is smaller than a second predetermined value;
When the second count value determining means determines that the increase / decrease in the count value is not equal to or greater than the second predetermined value, the specific stator that directly faces the first stator position to the rotor position First specific stator position specifying means for specifying the position;
The first count value corresponding to the increase / decrease number of the count value from the first stator position when the second count value determination means determines that the increase / decrease of the count value is equal to or greater than the second predetermined value. A second specific stator position specifying means for specifying the second stator position moved by the movement direction and the first movement amount as a specific stator position facing the rotor position;
A synchronous motor control device comprising: When it is determined by the first count value determination means that a period during which the increase / decrease in the count value is not equal to or greater than the first predetermined value does not continue for the predetermined period or longer, the count value is determined from the first stator position. Third stator position specifying means for specifying the third stator position moved by the second movement direction and the second movement amount corresponding to the increase / decrease number of
Control for supplying a current of a stator current vector necessary for the position of the rotor to face the third stator position specified by the third stator position specifying means to the stator winding Second current supply control means for performing
A third count value for determining whether or not a period during which the increase or decrease in the count value does not exceed the first predetermined value after the start of current supply control by the second current supply control means continues for the predetermined period or more; A determination means;
When it is determined by the third count value determination means that the period during which the increase / decrease in the count value does not exceed the first predetermined value continues for the predetermined period or longer, the third stator position is set to the rotor. A third specific stator position specifying means for specifying the specific stator position as opposed to the position of
The synchronous motor control device according to claim 1, comprising: A first movement direction and a movement amount that specify a third movement direction and a third movement amount of the rotor for causing the position of the rotor that faces the specific stator position to face the target stator position. Specific means,
A current of a stator current vector for causing the rotor to rotate according to the third movement direction and the third movement amount of the rotor specified by the first movement direction and movement amount specifying means is Third current supply control means for controlling the supply to the stator winding;
After the start of the current supply control by the third current supply control means, a first determination is made as to whether or not the count value is less than or equal to a third predetermined value or less from the count value corresponding to the third movement amount. 4 count value judging means;
When the fourth count value determining means determines that the count value is less than or equal to the third predetermined value from the count value corresponding to the third movement amount, it is output from the signal output means. Final stator position specifying means for specifying the final stator position based on the level of the
The synchronous motor control device according to claim 2, further comprising: When the fourth count value determining means determines that the count value is not an increase or decrease equal to or less than the third predetermined value from the count value corresponding to the third movement amount, it faces the specific stator position. A second moving direction that specifies a fourth moving direction and a fourth moving amount opposite to the previous moving direction of the rotor for causing the position of the rotor to face the target stator position. And a moving amount specifying means,
The third current supply control means causes the rotor to rotate in accordance with the fourth movement direction and the fourth movement amount of the rotor specified by the second movement direction and movement amount specification means. The synchronous motor control device according to claim 3, wherein control for supplying a current of a stator current vector for the stator winding to the stator winding is performed. A synchronous motor control method by a synchronous motor control device for controlling a synchronous motor including a rotor and a stator winding,
A signal output step of outputting a periodic signal while switching the level according to the position of the rotor;
A first stator that is considered to face the position of the rotor within a predetermined range determined by the period of the signal output in the signal output step based on the level of the signal output in the signal output step A first stator position specifying step for specifying a position;
A first current supply control step for performing control for supplying a current of a stator current vector necessary for the position of the stator to face the first stator position to the stator winding;
A count value that changes in accordance with the number of level switching times of the signal output in the signal output step after the start of current supply control in the first current supply control step and increases or decreases in accordance with the rotation direction of the rotor. A first count value determination step for determining whether or not a period during which the increase / decrease of the value does not exceed the first predetermined value continues for a predetermined period
When it is determined in the first count value determining step that the period during which the increase / decrease in the count value does not exceed the first predetermined value is continued for the predetermined period or longer, the increase / decrease in the count value is the first predetermined value. A second count value determination step for determining whether or not the second predetermined value is smaller than a second predetermined value,
When it is determined in the second count value determining step that the increase / decrease in the count value is not equal to or greater than the second predetermined value, the specific stator that directly faces the first stator position to the rotor position A first specific stator position identifying step for identifying a position;
When it is determined in the second count value determination step that the increase / decrease in the count value is greater than or equal to the second predetermined value, the first corresponding to the increase / decrease number in the count value from the first stator position. A second specific stator position specifying step for specifying the second stator position moved by the movement direction and the first movement amount as a specific stator position directly facing the rotor position;
A method for controlling a synchronous motor, comprising:

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