JP2011239541A - Motor controlling device and motor controlling method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor controlling device and motor controlling method that execute speed control with excellent responsiveness.SOLUTION: The motor controlling device comprises a position sensor 107 which detects a rotational position of a rotor 12 of a motor 10, a comparator circuit 102 which calculates a differential value between a current number of rotations of the motor 10 and a preset value, and an advance angle setting circuit 104 which sets an advance angle to generate a drive pulse obtained by advancing a pulse gained from the output of the position sensor 107. When the differential value is larger than a first threshold Th1, the advance angle setting circuit 104 sets the advance angle to give a higher torque than the one when the differential value is smaller than or equal to the first threshold Th1.

Description

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

  Patent Documents 1 to 3 disclose a brushless motor that switches a current flowing through a coil by a signal obtained by advancing the output of a position sensor that detects the rotational position of a rotor and prevents high-speed rotation by preventing a current rising delay. ing. Here, the phase of the drive pulse advanced with respect to the output pulse of the position sensor is called “advance angle”.

  In general, there is a relationship between the advance angle and the motor rotation speed (rotation speed) (pps: pulses / second), and the rotation speed increases as the advance angle increases. The rotational speed of the motor can be controlled by adjusting the advance angle so that the difference between the two becomes zero.

Japanese Patent Publication No. 06-0667259 JP 2002-359997 A JP-A-10-150798

  Conventional motor control devices perform feedback control that adjusts the advance angle by changing the duty ratio of the drive pulse so that the difference between the current rotational speed of the motor obtained from the position sensor and the set value becomes zero. . However, in this feedback control, the time required to obtain the desired rotation speed is relatively long, and the response is sometimes low.

  Accordingly, an object of the present invention is to provide a motor control device and a motor control method capable of performing speed control with excellent responsiveness.

  The motor control device according to the present invention is configured to determine the number of rotations of a motor having a stator having a coil and a rotor having a magnet and configured to be rotatable with respect to the stator. A motor control device that controls by changing an advance angle that is a phase, a position detection unit that detects a rotation position of the rotor of the motor, and a current rotation of the motor obtained from an output of the position detection unit A difference value calculation unit for calculating a difference value between the number and the set value, and an advance angle setting unit for setting the advance angle for generating the drive pulse obtained by advancing the pulse obtained from the output of the position detection unit; The advance angle setting means corresponds to the advance angle set when the difference value is less than or equal to the threshold value when the difference value calculated by the difference value calculation unit is greater than the threshold value. And sets the advance angle corresponding to high torque than torque.

  ADVANTAGE OF THE INVENTION According to this invention, the motor control apparatus and motor control method which can perform speed control excellent in the responsiveness can be provided.

FIG. 1 is a block diagram of the motor control device of this embodiment. FIG. 2 is a schematic cross-sectional view showing the relationship between the motor and the position sensor shown in FIG. FIG. 3 is a graph showing the relationship between the advance angle and torque of the motor shown in FIG. 1 for each rotation speed of the motor. 4A is a graph showing an example of a temporal change in the rotational speed of the motor shown in FIG. 1, and FIG. 4B is a difference value between the set value of the motor shown in FIG. 1 and the actual rotational speed. It is a graph which shows the example of a time change of. FIG. 5 is a graph showing the relationship between the torque and the rotational speed of the motor shown in FIG.

  FIG. 1 is a block diagram of a motor control device that controls the number of rotations (rotational speed) of the motor 10 of this embodiment.

  The motor 10 of this embodiment is a stepping motor that can operate as a brushless motor, and can be applied to, for example, a motor that drives a zoom lens of an imaging apparatus. However, the motor of the present invention only needs to have the function of a brushless motor, and includes a stator having a coil (stator) and a rotor having a magnet and configured to be rotatable with respect to the stator. It is enough if you have it.

  FIG. 2 is a schematic cross-sectional view of the motor 10 and the position sensor 107 in a plane perpendicular to the rotation axis of the motor 10. As shown in FIG. 2, the motor 10 has a rotor 12 having a cylindrical permanent magnet (magnet) 14 whose outer periphery is magnetized with a plurality of poles (S pole and N pole in FIG. 2). . The magnet 14 is magnetized so that the magnetic force in the radial direction changes substantially sinusoidally with respect to the angular position. In FIG. 2, the motor 10 is an inner rotor type, but the present invention can also be applied to an outer rotor type.

  The motor control device controls the rotation speed (rotation speed) of the motor 10 by changing the advance angle, which is the phase of the drive pulse of the current supplied to the coil. The motor control device has two control modes, a first control mode and a second control mode.

  The first control mode is a control mode in which the advance angle is changed so that the rotation speed of the motor 10 becomes a set value (target rotation speed) (that is, the difference between the two becomes zero). Corresponds to the mode. The second control mode is a control mode performed in place of the first control mode because the difference between the current rotational speed of the motor 10 and the set value is large and takes time in the first control mode. This is a control mode performed when it is necessary to change.

  The motor control device includes a rotation speed setting circuit 101, a comparison circuit 102, a first switch 103, an advance angle setting circuit 104, a motor driving circuit 105, a position sensor 107, a look-up table (LUT) 108, a second switch 109, and a switching circuit. 110 and a rotation speed detection circuit 111.

  The rotational speed setting circuit 101 is rotational speed setting means for setting the rotational speed of the motor 10. The rotation speed of the motor 10 set by the rotation speed setting circuit 101 is stored in advance in a memory (not shown) that is suitable for the electronic device on which the motor 10 is mounted. The electronic device on which the motor 10 is mounted may be provided with a function for manually setting the rotation speed.

  The comparison circuit 102 is connected to the rotation speed setting circuit 101 and the rotation speed detection circuit 111, and the output (set value) of the rotation speed setting circuit 101 and the output of the rotation speed detection circuit 111 (difference between the current rotation speed of the motor 10). A difference value calculation unit that calculates a value and outputs an amount corresponding to the difference value.

  The first switch 103 is ON / OFF (open / close) controlled by the switching circuit 110 and is provided between the comparison circuit 102 and the advance angle setting circuit 104. In the first control mode, the first switch 103 is closed and turned on, whereby the output of the comparison circuit 102 is supplied to the advance angle setting circuit 104. In the second control mode, the first switch 103 is opened and turned off, so that the output of the comparison circuit 102 is not supplied to the advance angle setting circuit 104.

  The advance angle setting circuit (advance angle setting means) 104 sets an advance angle for generating a drive pulse in which a pulse obtained from the output of the position sensor 107 is advanced. The advance angle setting circuit 104 is connected to the first switch 103, the position sensor 107, the second switch 109, and a memory (not shown). In this memory, the relationship between the advance angle and the rotation speed (rotation speed) of the motor 10 is stored. As described above, this relationship is generally a relationship in which the rotational speed of the motor 10 increases as the advance angle is increased.

  In the first control mode, the advance angle setting circuit 104 advances based on a relationship stored in a memory (not shown) so that the difference value output from the comparison circuit 102 becomes small (preferably zero). Set the corner. As a result, the rotational speed (rotational speed) of the motor 10 is feedback-controlled so that the current rotational speed of the motor 10 detected by the rotational speed detection circuit 111 matches the target rotational speed set by the rotational speed setting circuit 101. be able to. The advance angle setting circuit 104 increases the amount of change in advance when the absolute value of the difference value is large, and decreases the amount of change in advance when the absolute value of the difference value is small.

  In the second control mode, the advance angle setting circuit 104 sets the advance angle based on the information stored in the LUT 108 so that the difference value output from the comparison circuit 102 becomes small (preferably zero). To do. The advance angle range that can be set in the second control mode is different from the advance angle range that can be set in the first control mode, and is a range in which the relationship between the advance angle and the torque is non-linear (particularly from the first control mode). Also includes an advance angle or advance angle range that gives high torque.

  The motor drive circuit 105 is connected to the advance angle setting circuit 104, and is a drive means for supplying a current drive pulse to a coil (not shown) of the motor 10 so that the advance angle set by the advance angle setting circuit 104 is reflected. It is.

  The position sensor 107 detects the rotational position of the rotor 12 of the motor 10, and in this embodiment, is a position detection means constituted by a non-contact type magnetic detection element (magnetic sensor) constituted by a Hall element or the like. The position sensor 107 detects a magnetic change (magnetic pattern) of the magnet 14 accompanying the rotation of the rotor 12, and counts the number of changes to detect the position of the rotor 12.

  In FIG. 2, the position sensor 107 has a pair of magnetic poles 107 a and 107 b that detect magnetism, and the pair of magnetic poles 107 a and 107 b detect magnetic field changes accompanying rotation of the magnet 14, respectively. The position sensor 107 has one output terminal (not shown) for each of the pair of sensitive magnetic poles 107a and 107b, and a voltage signal proportional to the magnetic flux density detected by the corresponding sensitive magnetic pole is output from each output terminal. Is output.

  For example, if the magnetic flux passing through the magnetic sensing pole is N-pole, a positive voltage signal is output from the corresponding output terminal, and if the magnetic flux is S-pole, a negative voltage signal is output. . The output signal of the position sensor 107 is binarized by a binarization circuit (not shown) and is waveform-shaped as a pulse signal (first signal). The phase difference between the first signal and the drive pulse (second signal) obtained by advancing the first signal corresponds to the advance angle.

  The LUT 108 is provided in a memory such as a ROM, and as shown in FIG. 3 to be described later, discrete advance angle information indicating torque peaks in the advance angle-torque (T) characteristics for each rotation speed of the plurality of motors 10. Holding.

  The LUT 108 retains discrete advance angle information with respect to the rotation speed of the motor 10, thereby reducing the capacity compared to holding advance angle information with respect to the rotation speed of any motor 10. In this case, the advance angle setting circuit 104 obtains an advance angle corresponding to the actual rotation speed of the motor 10 from the advance angle information of the rotation speed adjacent thereto by interpolation calculation.

  Outputs from the switching circuit 110 and the rotation speed detection circuit 111 are input to the LUT 108, and advance angle information corresponding to the current rotation speed of the motor 10 is input to the advance angle setting circuit 104 via the second switch 109. Thereby, a present Example can change the rotation speed of the motor 10 efficiently.

  The second switch 109 is ON / OFF (open / close) controlled by the switching circuit 110 and is provided between the LUT 108 and the advance angle setting circuit 104. In the first control mode, since the second switch 109 is open and in the off state, the output of the LUT 108 is not supplied to the advance angle setting circuit 104.

  When the second switch 109 is closed and turned on, information on the LUT 108 is supplied to the advance angle setting circuit 104. The advance angle setting circuit 104 calculates and sets an appropriate advance angle by interpolation from the discrete advance angle information stored in the LUT 108 and the current rotation speed.

  The switching circuit 110 switches between the first control mode and the second control mode. The switching circuit 110 has a memory (not shown) that stores a threshold value of a difference value (or an absolute value of the difference value) output from the comparison circuit 102. The switching circuit 110 selects the first control mode when it is determined that the absolute value of the difference value output from the comparison circuit 102 is equal to or less than the threshold value, and selects the second control mode when it is determined that the absolute value is greater than the threshold value. select.

  Specifically, in the first control mode, the switching circuit 110 closes the first switch 103 and opens the second switch 109, and in the second control mode, the switching circuit 110 opens the first switch 103 and opens the second switch 109. close. The switching circuit 110 instructs the LUT 108 to read advance angle information to the advance angle setting circuit 104 in the second control mode.

  In this embodiment, the switching circuit 110 determines the absolute value of the difference and the threshold value. However, another control unit or the like makes this determination, and the switching circuit 110 operates based on the determination result of the control unit. May be.

  The rotation speed detection circuit 111 has a pulse counter (not shown) that detects the rotation speed of the rotor by counting changes per unit time of the position sensor 107 and counts the number of pulses of the pulse signal of the position sensor 107.

  FIG. 3 is a graph showing the advance angle and torque characteristics of the motor 10 according to the present embodiment for each number of rotations of the motor 10. The horizontal axis is the advance angle (°), and the vertical axis is the torque (T: unit is N). · M or kgf · m). In FIG. 3, C1 to C4 indicate the advance angle-torque characteristics when the rotation speed of the motor 10 is 1500 ppm, 2000 pps, 3000 pps, and 4000 pps, respectively, and torque peaks at different advance angles for each rotation speed. It can be seen that exists.

  In the first control mode, in this embodiment, the motor is driven in the advance angle range R of FIG. 3 when the rotational speed is 1500 ppm. In the advance angle range R, linear approximation is possible in the advance angle-torque characteristic, so that the control characteristic can be easily grasped and the design becomes easy. However, when this advance angle range is also applied to the second control mode, there is a problem that speed control takes time because there is no advance angle corresponding to the torque peak.

  Therefore, the advance angle setting circuit 104 of this embodiment sets an advance angle corresponding to a torque higher than the torque corresponding to the advance angle set in the first control mode when the difference value is larger than the threshold value. Thereby, the responsiveness is improved as compared with the prior art. In this case, the advance angle setting circuit 104 may set an advance angle corresponding to the torque peak in FIG. By using the advance angle that can generate the most torque, it is possible to drive the motor with improved response characteristics.

  Hereinafter, the motor control operation of this embodiment will be described with reference to FIG. FIG. 4A is a graph showing an example of a temporal change in the rotational speed of the motor 10, and FIG. 4B is a time of a difference value between the set rotational speed of the motor 10 and the actual rotational speed. It is a graph which shows an example of a change. FIG. 4B corresponds to a temporal change in the output of the comparison circuit 102.

  It is assumed that the set value of the rotation speed by the rotation speed setting circuit 101 changes from R1 to R2 at time T1 shown in FIG. 4A and is switched from R2 to R1 at time T4.

  Since the actual rotational speed of the motor 10 at time T1 is approximately R1, as shown in FIG. 4A, the differential value of the rotational speed is ΔR = R2−R1 (see FIG. 4B). . The advance angle setting circuit 104 sets an advance angle so as to reduce the difference value of the rotation speed (that is, to zero), and the motor drive circuit 105 drives the motor 10 to accelerate.

  At this time, in this embodiment, a threshold value of the difference value of the rotation speed (for example, a first threshold value Th1 shown in FIG. 4B) is provided, and the second control mode and the first control mode are switched. In this embodiment, the second threshold value Th2 shown in FIG. 4A is provided, and the advance angle value to be used is changed between the case where the rotational speed of the motor 10 is larger than the second threshold value Th2 and the following case. Yes.

  At the time of acceleration between times T1 and T3 shown in FIG. 4B, the difference value of the rotation speed is equal to or greater than the first threshold value Th1, so that the second control mode is set, and the difference value of the rotation speed is the first threshold value at time T3. Since it becomes equal to Th1, the switching circuit 110 switches the second control mode to the first control mode.

  Since the actual rotational speed of the motor 10 at time T4 is substantially R2, as shown in FIG. 4A, the difference value of the rotational speed is −ΔR = R1−R2 (see FIG. 4B). ). The advance angle setting circuit 104 sets an advance angle so as to decrease the difference value of the rotation speed (that is, to zero), and the motor drive circuit 105 drives the motor 10 to decelerate.

  Here, the mode is not switched until the rotation speed of the motor 10 reaches the set value. As a result, in this embodiment, as shown in FIG. 4B, driving is performed in the second control mode from time T4 to time T5, and when the rotational speed reaches the set value at time T5, the first control mode is entered. Transition.

  As described above, in this embodiment, different switching is performed at the time of acceleration for increasing the rotation speed of the motor 10 and at the time of deceleration for decreasing the rotation speed of the motor 10, that is, switching between the second control mode and the first control mode. (The threshold for -ΔR is 0). As a result, in FIG. 4, the advance angle setting circuit 104 varies the amount of advance angle to be changed when the absolute value of the difference value is the same but the sign is opposite. As a result, it is possible to perform control that matches the acceleration characteristics including the mechanical characteristics and the deceleration characteristics.

  Further, in this embodiment, only the first threshold value Th1, which is a positive threshold value, is provided, and the corresponding negative threshold value -Th1 is not provided, so that a wide range of the second control mode during deceleration is ensured. . As a result, in FIG. 4, the time required to decrease the rotational speed from R2 to R1 is shorter than the time required to increase the rotational speed from R1 to R2.

  This is because, as shown in FIG. 3, since the torque peak is on the side where the advance angle is small, it is not possible to secure a wide range of the second control mode so as to approach the torque peak when decelerating the advance angle. This is because it is advantageous in improving responsiveness. However, in the present invention, a third threshold value of -Th1 may be provided, and the first control mode may be performed between the first threshold value Th1 and the third threshold value -Th1.

  When the motor 10 is applied to an imaging apparatus, in this embodiment, it is determined whether the lens barrel is retracted when the power is turned on. If the lens barrel is retracted, the motor 10 is rotationally driven to extend the lens barrel by a predetermined amount. At this time, the motor 10 is required to quickly increase its rotational speed.

  In this embodiment, for example, when the power is turned on, the rotation speed of the motor 10 is increased from 0 ppm to 4000 ppm in the second control mode. When the lens barrel is extended when the power is turned on, the advance angle setting circuit 104 sets the advance angle data according to the rotational speed of the rotor. For example, the switching circuit 110 switches to the first control mode when the rotational speed of the rotor 12 reaches 3500 ppm.

  Thereafter, the first control mode continues and the motor 10 is driven at 4000 ppm. In this embodiment, when the motor 10 is applied to an image pickup apparatus, it is possible to shorten an extension time of the lens barrel from a retracted state such as when the power is turned on.

  In this way, the second control mode may be activated only when the lens barrel is extended (acceleration). This is because in the case of storing the lens barrel, since it is after the end of shooting, there is no problem even if the lens barrel storage time is extended for the photographer. Thereby, an energy saving effect is also obtained.

  In another embodiment, an advance angle to be set for each range of the rotation speed of the motor 10 is used in the second control mode. FIG. 5 is a graph showing the relationship between the torque of the motor 10 and the rotational speed for each advance angle, and is stored in the LUT 108 (or memory). In FIG. 5, the horizontal axis represents torque (T: the unit is N · m or kgf · m), and the vertical axis represents the rotation speed (pps) of the motor 10. When the advance angle is 0 °, the maximum torque is relatively large, but the maximum rotational speed is low. As the advance angle increases, the maximum torque decreases, but the maximum rotational speed increases.

  In the second control mode, the switching circuit 110 reads the advance angle from the LUT 108 and sets it in the advance angle setting circuit 104 according to the output of the rotation speed detection circuit 111. As a result, the advance angle setting circuit 104 has an advance angle of 0 ° in the range where the rotational speed is from 0 ppm to less than 1500 rpm, an advance angle of 10 ° in the range where the rotational speed is from 1500 ppm to less than 2000 ppm, and the rotational speed is from 2000 ppm to less than 3000 ppm. In the range, an advance angle of 20 ° is used. The advance angle setting circuit 104 uses an advance angle of 30 ° when the rotational speed is in the range of 3000 ppm to less than 4000 ppm, and an advance angle of 40 ° when the rotational speed is 4000 rpm or more.

  As a result, in this embodiment, the number of rotation speed ranges and the number of lead angle data can be reduced, and the memory capacity can be reduced to reduce the cost.

  In FIG. 1, the comparison circuit 102 and the advance angle setting circuit 104 can be performed by a single microcomputer (control means or processor). In this case, the microcomputer executes a motor control method for controlling the rotation speed of the motor 10 by changing the advance angle which is the phase of the drive pulse of the current supplied to the coil. This motor control method includes a step of calculating a difference value between the current rotational speed of the motor 10 and a set value, and an advance angle setting step of setting an advance angle for generating a drive pulse. In the advance angle setting step, when the difference value is larger than the threshold value, an advance angle corresponding to a torque higher than the torque corresponding to the advance angle set when the difference value is equal to or smaller than the threshold value is set. The motor control method can be embodied as a program that can be executed by a computer.

  As mentioned above, although the preferable Example of this invention was described, this invention is not limited to these Examples, A various deformation | transformation and change are possible within the range of the summary.

  The motor control device can be applied to an application for controlling the rotational speed of the motor.

10 Motor 101 Rotation speed setting circuit (Rotation speed setting means)
102 Comparison circuit (difference value calculation unit)
104 Advance angle setting circuit (advance angle setting means)
107 Position sensor (position detection means)
111 Rotation speed detection circuit

Claims (5)

The rotation speed of a motor having a stator having a coil and a rotor having a magnet and configured to be rotatable with respect to the stator is changed in an advance angle which is a phase of a driving pulse of a current supplied to the coil. A motor control device controlled by
Position detecting means for detecting the rotational position of the rotor of the motor;
A difference value calculation unit for calculating a difference value between a current rotation number of the motor and a set value obtained from the output of the position detection unit;
Advance angle setting means for setting the advance angle for generating the drive pulse in which the pulse obtained from the output of the position detection means is advanced;
Have
When the difference value calculated by the difference value calculation unit is greater than a threshold value, the advance angle setting means sets a torque higher than the torque corresponding to the advance angle set when the difference value is equal to or less than the threshold value. A motor control device characterized by setting a corresponding advance angle. A memory for discretely holding advance angle information to be set for each rotation speed of the motor;
2. The motor control apparatus according to claim 1, wherein the advance angle setting means acquires an advance angle corresponding to the current rotation speed of the motor from the information by interpolation calculation. A memory for holding information on an advance angle to be set for each range of the rotational speed of the motor;
The motor control apparatus according to claim 1, wherein the advance angle setting unit acquires an advance angle corresponding to a current rotational speed of the motor from the information.   4. The advance angle setting unit varies the amount of advance angle that is changed when the absolute value of the difference value is the same even when the sign is opposite. 4. Motor control device. The rotation speed of a motor having a stator having a coil and a rotor having a magnet and configured to be rotatable with respect to the stator is changed in an advance angle which is a phase of a driving pulse of a current supplied to the coil. A motor control method for controlling by
Calculating a difference value between a current rotation number of the motor and a set value;
An advance angle setting step for setting the advance angle for generating the drive pulse;
Have
In the advance angle setting step, when the difference value is larger than a threshold value, the advance angle setting step sets an advance angle corresponding to a torque higher than the torque corresponding to the advance angle set when the difference value is equal to or smaller than the threshold value. A motor control method.