JP6184221B2 - Motor drive control device, motor and drive control method thereof - Google Patents

Description

  The present invention relates to a motor drive control device, a motor, and a drive control method thereof, and more particularly, to a device that detects a rotational position using a position detector.

  Conventionally, as a drive control device for a position control motor, there is a control device that selectively switches between an open loop stepping motor drive method that switches excitation by an external command pulse (drive pulse) and a closed loop brushless motor drive method. Are known. As a result, the motor does not step out and can thus operate stably against load fluctuations.

  The invention described in Patent Document 1 adjusts the timing of the winding drive signal by using a single-phase encoder having a number of pulses larger than the number of steps of the motor in order to drive the motor in the brushless motor mode.

  The invention described in Patent Document 2 switches between stepping motor mode driving (microstep) and brushless motor mode driving in accordance with a two-phase encoder signal indicating the driving timing of the brushless motor mode and an external command. is there.

JP-A-11-113289 Japanese Patent Laid-Open No. 3-74199

  In the motors described in Patent Documents 1 and 2, the encoder used is expensive. Furthermore, an expensive microcomputer or the like is necessary for the drive control means.

  Therefore, the present invention provides a motor drive control device, a motor, and a drive control method thereof that enable a stable operation with respect to a load fluctuation by following a rotor without stepping out while having an inexpensive configuration. The task is to do.

  In order to solve the above-described problems, the control unit of the present invention is configured as follows.

According to the first aspect of the present invention, a motor drive control device includes: a drive unit that outputs a drive signal to each phase of a two-phase motor based on a drive command signal; and a control unit that outputs the drive command signal. Including. The control unit is based on a brushless motor drive timing generation circuit that generates a brushless motor drive timing signal based on a detection signal from a position detector that detects a rotor position of the motor, and a drive pulse input from the outside. A stepping motor drive timing generation circuit for generating a stepping motor drive timing signal, a reference timing generation circuit for generating a reference timing signal obtained by dividing the drive pulse , and the brushless motor drive from a level change edge of the reference timing signal Comparing whether the level change edge of the timing signal is delayed by a predetermined phase or more, and generating a comparison information, and based on the comparison information, the stepping motor drive timing signal and the brushless motor drive timing signal Either And-option, a mode selection circuit for outputting as said drive command signal, by counting the delay of the level change edge of the brushless motor driving timing signal for the level change edge of the reference timing signal, and a deviation counter to accumulate the pulse signal with Ru. The control unit continues to select the brushless motor drive timing signal and outputs it as the drive command signal if the pool pulse signal exists, and the stepping motor drive timing if the pool pulse signal disappears. At the next edge of the signal, the stepping motor drive timing signal is selected and output as the drive command signal. The brushless motor drive timing signal is a signal with a fixed advance value advanced in a range of 45 degrees ± 12.5 degrees.

  In this way, when the drive control device detects the phase delay of the detection signal of the position detector while driving the motor with the stepping motor drive timing signal, the drive control device drives with the brushless motor drive timing signal. Switch as follows. Therefore, it is possible to suppress the motor step-out with an inexpensive configuration.

According to a fourth aspect of the present invention, a drive control device that executes a motor drive control method includes: a drive unit that outputs a drive signal to each phase of a two-phase motor based on a drive command signal; and the drive command signal And a control unit for outputting. The control unit generates a brushless motor drive timing signal with a fixed advance value that is advanced in a range of 45 degrees ± 12.5 degrees based on a detection signal from a position detector that detects the rotor position of the motor. And generating a stepping motor drive timing signal based on a drive pulse input from the outside, generating a reference timing signal obtained by dividing the drive pulse, and driving the brushless motor from the level change edge of the reference timing signal. A comparison information is generated by comparing whether or not a level change edge of the timing signal is delayed by a predetermined phase or more, and based on the comparison information, either the stepping motor drive timing signal or the brushless motor drive timing signal is selected, and output as the drive command signal, a level change edge of the reference timing signal The delay of the level change edge of the brushless motor drive timing signal is counted as a pool pulse signal, and if the pool pulse signal exists, the selection of the brushless motor drive timing signal is continued as the drive command signal. When the accumulated pulse signal is output, at the next edge of the stepping motor drive timing signal, switching to the selection of the stepping motor drive timing signal and outputting it as the drive command signal , the motor drive control Execute the method.

In this way, when the drive control device detects the phase delay of the detection signal of the position detector while driving the motor with the stepping motor drive timing signal, the drive control device drives with the brushless motor drive timing signal. Switch as follows. Therefore, it is possible to suppress the motor step-out with an inexpensive configuration.
Other means will be described in the embodiment for carrying out the invention.

  According to the present invention, a highly reliable motor drive control device that can follow a command position without stepping out of the command position and enables stable operation against load fluctuations while having an inexpensive configuration. A motor and its drive control method can be provided.

It is a schematic block diagram which shows the drive control apparatus of the motor in 1st Embodiment. It is a timing chart which shows a case where there is no current delay among drive timings (advance 45 degrees) in the stepping motor mode. It is a timing chart which shows the case where a current delay is 25 degree | times among the drive timings (advance angle 45 degree | times) in a stepping motor mode. It is a timing chart which shows that a step-out occurs due to the rotor being delayed at the time of driving at a current delay of 25 degrees out of the driving timing (advance angle of 45 degrees) in the stepping motor mode. It is a timing chart which shows the drive timing (no advance angle, no current delay) in the brushless motor mode. It is a timing chart which shows the drive timing (45 degrees advance, no current delay) in brushless motor mode. It is a timing chart which shows the state which switched to brushless motor mode and prevented step-out when the rotor was delayed at the time of driving with a current delay of 25 degrees out of the drive timing (advance angle of 45 degrees) in the stepping motor mode. 6 is a timing chart showing that positioning control can be performed by switching to a stepping motor mode when the rotor has advanced during driving at the driving timing (advance angle 45 degrees) in the brushless motor mode. It is a graph which shows the specific example of the torque curve with respect to each advance value. It is a schematic block diagram which shows the drive control apparatus of the motor in 2nd Embodiment. It is a timing chart which shows the state which a motor heads out of step in stepping motor mode (advance 45 degrees). It is a timing chart which shows avoidance of the step-out by switching from the stepping motor mode (advance angle 45 degrees) to the brushless motor mode.

Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.
(First embodiment)
FIG. 1 is a schematic configuration diagram of a drive control device 10 for a motor 20 in the first embodiment.
As shown in FIG. 1, the motor 20 includes a two-phase encoder 30 (an example of a position detector). The motor 20 includes a two-phase coil (not shown) of a sin phase and a cos phase, and a rotor (not shown) that is rotationally driven by a magnetic field generated in the two-phase coil. The two-phase encoder 30 detects the rotational position of a rotor (not shown).
The two-phase encoder 30 is configured separately or integrally with the motor 20 and is encoder signals Se1 and Se2 (phase is 90) that are advanced by approximately 45 degrees (an example of a predetermined advance value θ) from the drive timing in the brushless motor mode. It is adjusted in advance so as to output two-phase signals different from each other; an example of a detection signal. The two-phase encoder 30 detects the rotor position of the motor 20 and outputs two encoder signals Se1 and Se2 that are 90 degrees out of phase. The frequency fe of the encoder signals Se1 and Se2 is obtained by multiplying the driving frequency fb in the brushless motor mode by m times (m is a natural number) as shown in the equation (1). The magnification m of the first embodiment is 1, and the frequency fe of the encoder signals Se1 and Se2 and the drive frequency fb in the brushless motor mode are the same.
The brushless motor mode will be described in detail with reference to FIGS.

The drive control device 10 for the motor 20 includes a drive circuit 11 (an example of a drive unit) and a control unit 12. The drive control device 10 outputs drive signals Sd1 and Sd2 (an example of drive current) to each phase of the two-phase motor 20 based on a drive pulse signal Sp (an example of drive pulse) input from the outside, The motor 20 is rotationally driven to control the rotational position of the rotor.
The control unit 12 outputs drive command signals Sm1 and Sm2 for instructing driving of the motor 20 based on comparison information obtained by comparing the encoder signals Se1 and Se2 and the drive pulse signal Sp from the outside. To control.
The drive circuit 11 (an example of a drive unit) outputs drive signals Sd1 and Sd2 to each phase of the two-phase motor 20 based on the drive command signals Sm1 and Sm2.

(Configuration of control unit 12)
The control unit 12 includes a reference timing generation circuit 17, a brushless motor drive timing generation circuit 15, a stepping motor drive timing generation circuit 14, a comparison circuit 16, and a mode selection circuit 13. In FIG. 1, the brushless motor drive timing generation circuit 15 is abbreviated as “BLM drive timing generation circuit”. Hereinafter, similarly, the brushless motor may be abbreviated as “BLM”.
In FIG. 1, the stepping motor drive timing generation circuit 14 is abbreviated as “STM drive timing generation circuit”. Similarly, the stepping motor is sometimes abbreviated as “STM” in some cases.

The reference timing generation circuit 17 generates a reference timing signal Sr based on a drive pulse signal Sp (an example of a drive pulse) input from the outside. The reference timing generation circuit 17 generates the reference timing signal Sr by dividing the drive pulse signal Sp by 8 and synchronizing it with the stepping motor drive timing signals Ss1, Ss2.
The frequency fp of the drive pulse signal Sp is a frequency obtained by multiplying the drive frequency fs at the time of driving in the stepping motor mode by the magnification p, as shown in Expression (2). The magnification p is a value obtained by dividing a value obtained by dividing 90 degrees by a predetermined advance value θ by n times (n is a natural number).

The driving pulse signal Sp of the first embodiment has a frequency that is eight times the driving frequency during driving in the stepping motor mode. That is, the advance value θ of the encoder signals Se1 and Se2 is 45 degrees, and n is 4.
The reference timing signal Sr is a signal indicating switching between the stepping motor drive timing signals Ss1 and Ss2 and the brushless motor drive timing signals Sb1 and Sb2. The reference timing generation circuit 17 outputs the generated reference timing signal Sr to the comparison circuit 16.

The brushless motor drive timing generation circuit 15, based on the encoder signals Se 1 and Se 2 (two-phase detection signals) input from the two-phase encoder 30, combines the encoder signal Se (synthesis detection signal) and the brushless motor drive timing. Signals Sb1 and Sb2 are generated. The brushless motor drive timing generation circuit 15 amplifies the encoder signal Se1 to generate a brushless motor drive timing signal Sb1, and amplifies the encoder signal Se2 to generate a brushless motor drive timing signal Sb2. The brushless motor drive timing generation circuit 15 synthesizes the encoder signal Se by, for example, exclusive OR of the brushless motor drive timing signals Sb1 and Sb2. The brushless motor drive timing generation circuit 15 outputs the generated brushless motor drive timing signals Sb1 and Sb2 to the mode selection circuit 13 and outputs the combined encoder signal Se to the comparison circuit 16.
Note that the brushless motor drive timing generation circuit 15 may synthesize the encoder signal Se by a logical operation other than exclusive OR.

  The stepping motor drive timing generation circuit 14 generates stepping motor drive timing signals Ss1, Ss2 based on a drive pulse signal Sp input from the outside. The stepping motor drive timing generation circuit 14 of the first embodiment divides the drive pulse signal Sp by 8 to generate stepping motor drive timing signals Ss1 and Ss2 that are 90 degrees out of phase. The stepping motor drive timing generation circuit 14 outputs the generated stepping motor drive timing signals Ss1, Ss2 to the mode selection circuit 13.

  The comparison circuit 16 outputs a mode switching signal Sc (an example of comparison information) based on the reference timing signal Sr from the reference timing generation circuit 17 and the encoder signal Se from the brushless motor drive timing generation circuit 15. . The comparison circuit 16 determines whether or not the level change edge of the encoder signal Se is delayed by a predetermined phase (electrical angle 90 degrees of the reference signal) from the level change edge of the reference timing signal Sr, and the mode switching signal Sc (comparison) An example of information) is output. The encoder signal Se is an exclusive OR of the brushless motor drive timing signals Sb1 and Sb2. Therefore, the level change edge of the brushless motor drive timing signals Sb1 and Sb2 can be determined from the level change edge of the encoder signal Se.

The mode selection circuit 13 receives the brushless motor drive timing signals Sb1 and Sb2 and the stepping motor drive timing signals Ss1 and Ss2, and based on the mode switching signal Sc, the drive command signal Sm1 corresponding to the drive mode of the motor 20 Sm2 is output to the drive circuit 11.
The mode selection circuit 13 selects the brushless motor drive timing signals Sb1 and Sb2 when the mode switch signal Sc is at the H level and outputs them as drive command signals Sm1 and Sm2. When the mode switch signal Sc is at the L level, the mode selection circuit 13 performs stepping. Motor drive timing signals Ss1, Ss2 are selected and output as drive command signals Sm1, Sm2. The operation of the mode selection circuit 13 is not limited to this embodiment. For example, when the mode switching signal Sc is at the H level, the stepping motor drive timing signals Ss1, Ss2 are selected, and the mode switching signal Sc Brushless motor drive timing signals Sb1 and Sb2 may be selected and output as drive command signals Sm1 and Sm2 at the L level.

Hereinafter, the operation of each unit of the control unit 12 will be described with reference to the timing charts of FIGS. 2 to 8, the horizontal axis indicates a common electrical angle [deg].
“Motor output torque waveform” indicates a waveform of the output torque of the motor 20 by a solid line.
The “torque waveform of each phase” indicates the torque waveform of the sin phase and the cos phase of the motor 20 by a solid line and a broken line, respectively. Similarly, each signal relating to the sin phase of the motor 20 is indicated by a solid line, and each signal relating to the cos phase is indicated by a broken line.
“Driving signal Sd for each phase” indicates the waveforms of the driving signals Sd1 and Sd2 input to the sin phase and the cos phase of the motor 20 by solid lines and broken lines, respectively.
“Back electromotive force of each phase” indicates a waveform of the back electromotive force of the sin phase and the cos phase, respectively, by a solid line and a broken line. The back electromotive force is a virtual signal indicating the magnitude and direction of torque generation.

The “mode switching signal Sc” is a signal for selecting one of the brushless motor drive timing signals Sb1 and Sb2 and the stepping motor drive timing signals Ss1 and Ss2.
The “STM drive timing signal Ss” indicates a sin phase stepping motor drive timing signal Ss1 by a solid line, and a cos phase stepping motor drive timing signal Ss2 by a broken line.
“BLM drive timing signal Sb” is a case where the magnification m = 1, and a solid line indicates a sin-phase brushless motor drive timing signal Sb1, and a broken line indicates a cos-phase brushless motor drive timing signal Sb2. The brushless motor drive timing signals Sb1 and Sb2 are signals obtained by amplifying the encoder signals Se1 and Se2, respectively, and are signals for indicating a level change edge of the brushless motor drive timing.
The “encoder signal Se” is a signal obtained by synthesizing the encoder signals Se1 and Se2 by exclusive OR.
The “reference timing signal Sr” is a signal obtained by dividing the drive pulse signal Sp by eight.
The “drive pulse signal Sp” indicates a case where the magnification is p = 8 (n = 4 and the advance value θ = 45 degrees) in the time charts shown in FIGS.

(Stepping motor mode operation)
The operation in the stepping motor mode will be described with reference to FIGS. Here, the stepping motor mode refers to a mode in which the control unit 12 selects the stepping motor drive timing signals Ss1, Ss2 and outputs them as drive command signals Sm1, Sm2.
FIG. 2 is a timing chart showing a case where there is no current delay among the drive timings in the stepping motor mode. At this time, the motor 20 is at a relatively low speed, the load is not excessive, and there is no current delay.
As shown in FIG. 2, all the level change edges of the encoder signal Se follow each level change edge of the reference timing signal Sr with a delay of a predetermined phase (an electrical angle of the reference signal of about 90 degrees). . At this time, the mode switching signal Sc is at the L level. When the mode switching signal Sc becomes L level, the stepping motor drive timing signals Ss1, Ss2 are selected as the drive command signals Sm1, Sm2 at the next edge of the stepping motor drive timing signals Ss1, Ss2. Therefore, the drive signal Sd for each phase is controlled by the stepping motor drive timing signals Ss1, Ss2.

FIG. 3 is a timing chart showing a case where the current delay is 25 degrees among the drive timings in the stepping motor mode.
Each level change edge of the encoder signal Se follows the level change edge of the reference timing signal Sr with a delay of 25 degrees with respect to the electrical angle of the predetermined phase shown in FIG. It is followed by a delay. At this time, the mode switching signal Sc is at the L level. Stepping motor drive timing signals Ss1, Ss2 are selected as the drive command signals Sm1, Sm2. Therefore, the drive signal Sd for each phase is controlled by the stepping motor drive timing signals Ss1, Ss2.

FIG. 4 is a timing chart showing that a step-out occurs due to a delay of the rotor during driving in the stepping motor mode. From the state of the current delay of 25 degrees shown in FIG. 3, the load on the motor 20 is increased, the delay of the rotor is further increased, and a step-out has occurred. The step-out means a state in which the output torque of the motor 20 is negative and does not rotate in the commanded direction.
The rising edge (level change edge) of the encoder signal Se in the vicinity of the electrical angle of 45 degrees in FIG. 4 is relative to the rising edge (level change edge) in the vicinity of the electrical angle of 0 degrees (not shown) of the corresponding reference timing signal Sr. The electrical angle of the reference signal is delayed by about 140 degrees.

Thereafter, each level change edge of the encoder signal Se gradually increases in electrical angle delay with respect to each level change edge of the corresponding reference timing signal Sr.
For example, the rising edge of the encoder signal Se in the vicinity of the electrical angle 450 degrees in FIG. 4 is delayed by about 90 degrees in electrical angle with respect to the corresponding rising edge of the reference timing signal Sr (near 360 degrees electrical angle). Yes. From this time onward, the output torque waveform of the motor 20 continuously becomes a negative value, resulting in a step-out state in which the motor 20 does not rotate in the commanded direction.

(Brushless motor mode operation)
The operation in the brushless motor mode will be described with reference to FIGS. Here, the brushless motor mode refers to a mode in which the control unit 12 selects brushless motor drive timing signals Sb1 and Sb2 obtained by amplifying the encoder signals Se1 and Se2 and outputs them as drive command signals Sm1 and Sm2.

FIG. 5 is a timing chart showing a case where there is no advance angle and no current delay among the drive timings in the brushless motor mode.
The timing chart shown in FIG. 5 is a case where the two-phase encoder 30 is adjusted in advance without an advance angle, and the drive control device 10 is operated in the brushless motor mode.
As shown in FIG. 5, at the drive timing in the brushless motor mode without advance angle, the period in which the sin phase drive signal Sd1 is at the H level coincides with the period in which the sin phase back electromotive force is positive. Similarly, the period in which the cos-phase drive signal Sd1 is at the H level coincides with the period in which the cos-phase back electromotive force is positive.

  The two-phase encoder 30 outputs an encoder signal Se1 that coincides with a period in which the sin phase counter electromotive force is positive, and outputs an encoder signal Se2 that coincides with a period in which the cos phase counter electromotive force is positive. The encoder signals Se1 and Se2 are amplified to generate a brushless motor drive timing signal Sb (Sb1, Sb2). The brushless motor drive timing signal Sb is selected as a drive signal Sd (Sd1, Sd2) for each phase. In this way, the motor 20 can continue to rotate without stepping out in the brushless motor mode.

FIG. 6 is a timing chart showing a case where the advance angle is 45 degrees and there is no current delay among the drive timings in the brushless motor mode.
The timing chart shown in FIG. 6 is a case where the two-phase encoder 30 is adjusted in advance to be advanced by 45 degrees, and the drive control device 10 is operated in the brushless motor mode.
As shown in FIG. 6, at the drive timing of the brushless motor mode advanced by 45 degrees, the period when the sin phase drive signal Sd1 is at the H level is an electrical angle than the period when the sin phase back electromotive force is positive. It is 45 degrees ahead. Similarly, the period in which the cos-phase drive signal Sd1 is at the H level is advanced by 45 degrees in electrical angle from the period in which the cos-phase back electromotive force is positive.

The two-phase encoder 30 outputs the encoder signal Se1 advanced by 45 degrees from the period in which the sin phase counter electromotive force is positive, and is advanced 45 degrees from the period in which the cos phase counter electromotive force is positive. The encoder signal Se2 is output. The encoder signals Se1 and Se2 are amplified to generate a brushless motor drive timing signal Sb (Sb1, Sb2). The BLM drive timing signal Sb shown in FIG. 6 is advanced by 45 degrees compared to the BLM drive timing signal Sb shown in FIG.
The brushless motor drive timing signal Sb is selected as a drive signal Sd (Sd1, Sd2) for each phase. In this way, the drive control device 10 can output the drive signals Sd (Sd1, Sd2) of each phase advanced by 45 degrees.

(Operation of the first embodiment)
The operation of the first embodiment will be described with reference to FIGS.
FIG. 7 is a time chart showing a state in which step-out is prevented by switching to the brushless motor mode when the rotor is delayed during driving with a current delay of 25 degrees, among the driving timings in the stepping motor mode. The electrical angle of 0 to 450 degrees in the time chart of FIG. 7 is the same as the electrical angle of 0 to 450 degrees in the time chart of FIG.
The rising edge of the encoder signal Se near the electrical angle of 450 degrees in FIG. 7 is delayed by about 90 degrees of the electrical angle of the reference signal with respect to the corresponding rising edge of the reference timing signal Sr (near the electrical angle of 360 degrees). Yes.

  When the comparison circuit 16 detects that the delay of the level change edge of the encoder signal Se corresponding to the level change edge of the reference timing signal Sr exceeds 90 degrees in electrical angle, the mode switching signal Sc is set to the H level. Set. When the mode switching signal Sc becomes H level and the next edge of the brushless motor drive timing signals Sb1 and Sb2 is detected, the mode selection circuit 13 selects the brushless motor drive timing signals Sb1 and Sb2 and drives the drive command signal. Output as Sm1, Sm2. The motor output torque waveform has a predetermined positive value. Thereby, the drive control apparatus 10 can drive the motor 20 without stepping out.

FIG. 8 is a time chart showing that the positioning control is enabled by switching to the stepping motor mode when the rotor advances during driving at the driving timing in the brushless motor mode. The time chart of FIG. 8 is, for example, after the time chart of FIG.
The falling edge of the encoder signal Se in the vicinity of the electrical angle of 200 degrees is delayed by about 110 degrees in terms of the electrical angle of the reference signal with respect to the corresponding falling edge of the reference timing signal Sr (near the electrical angle of 90 degrees). doing.
The falling edge of the encoder signal Se at an electrical angle of 360 degrees is delayed by about 90 degrees in terms of the electrical angle of the reference signal from the corresponding falling edge of the reference timing signal Sr (near the electrical angle of 270 degrees). Yes.

The comparison circuit 16 detects that the delay of the level change edge of the encoder signal Se corresponding to the level change edge of the reference timing signal Sr is less than 90 degrees in electrical angle, and the stepping motor drive timing signals Ss1, Ss2 When the next level change edge is detected, the mode switching signal Sc is set to the L level. In the vicinity of the electrical angle of 450 degrees in FIG. 8, the mode switching signal Sc is switched from the H level to the L level.
If the mode switching signal Sc is at the L level, the mode selection circuit 13 selects the stepping motor drive timing signals Ss1, Ss2 and outputs them as drive command signals Sm1, Sm2. Thereby, the drive control apparatus 10 can perform positioning control of the motor 20 again.

FIG. 9 is a graph showing a torque curve corresponding to each advance value in the brushless motor mode and a torque curve corresponding to the stepping motor mode. The vertical axis in FIG. 9 indicates the motor torque in millinewton meters (mN · m). The horizontal axis in FIG. 9 indicates the rotational speed in terms of the number of rotations per minute (r / min).
“No advance” is a torque curve of the motor when the drive command signals Sm1, Sm2 are applied at the drive timing in the brushless motor mode. “Advance 25 °”, “Advance 32.5 °”, “Advance 45 °”, “Advance 57.5 °”, and “Advance 70 °” indicate that the drive command signals Sm1 and Sm2 are brushless. It is a torque curve of a motor when it advances and gives only each electrical angle with respect to the drive timing in a motor mode. “STM drive” is a torque curve when driven in the stepping motor mode.

  As shown in FIG. 9, the drive control device 10 (see FIG. 1) performs drive control by switching between both the brushless motor drive timing signals Sb1 and Sb2 advanced by a predetermined value and the stepping motor mode. As a result, the drive control device 10 can expand the range to a rotational speed in a high speed region (in FIG. 9, a region of about 1750 (r / min or higher)) than the range of the normal torque curve characteristics as a stepping motor. In particular, by switching to the brushless motor drive timing signals Sb1 and Sb2 that are advanced by 45 degrees, it is possible to drive with a high torque even at a high rotational speed, and the drive control device 10 can detect the positive of the motor 20. Since switching between rotation and reverse rotation can be realized only by exchanging signals, the advance value is an optimum value of 45 degrees, but is not limited to this, and the advance value is 45 ± 12. If it is in the range of 5 degrees, a desired torque can be obtained in a predetermined rotational speed range.

The drive control device 10 switches between the stepping motor mode and the brushless motor mode without using an expensive and complicated device such as a high-resolution encoder or a microcomputer, and an inexpensive position detector such as the two-phase encoder 30. It can be realized only with a simple logic circuit such as the control unit 12.
When driving in the stepping motor mode, the drive control device 10 can be switched to the brushless motor mode and rotated without stepping out even if a load more than expected is applied to the motor 20. Thereby, since the torque characteristic of the motor 20 is improved and step-out can be avoided, the motor 20 can be made smaller than before.

  According to the first embodiment, the magnetic pole position of the stepping motor can be detected with a pulse encoder that can output a signal having a phase difference of 90 degrees with one sensor. This pulse encoder is inexpensive. Therefore, the robust performance of this stepping motor can be raised to the same level as a brushless motor at a slight cost, and step-out due to disturbance can be suppressed.

(Second Embodiment)
Unlike the first drive control device 10, the motor drive control device of the second embodiment counts the deviation of the level change edge of the encoder signal Se with respect to the level change edge of the reference timing signal Sr, and uses this deviation. Based on this, switching between the stepping motor mode and the brushless motor mode is performed. Thereby, the step-out of the motor 20 can be reliably avoided, and the rotational position commanded by the drive pulse signal Sp can be recovered by the motor 20.

FIG. 10 is a schematic configuration diagram illustrating the drive control device 10a of the motor 20 according to the second embodiment. The same components as those of the drive control device 10 for the motor 20 of the first embodiment shown in FIG.
As shown in FIG. 10, the drive control device 10a for the motor 20 includes a control unit 12a different from the control unit 12 of the first embodiment. Other than that, the configuration is the same as that of the drive control apparatus 10 of the first embodiment.

The control unit 12a of the second embodiment includes a deviation counter 18 (an example of a pool pulse detector), and includes a comparison circuit 16a different from the comparison circuit 16 of the first embodiment. Other than that, it is comprised similarly to the control part 12 of 1st Embodiment.
The comparison circuit 16a determines whether or not the level change edge of the encoder signal Se is behind the level change edge of the reference timing signal Sr, and outputs a signal for increasing or decreasing the deviation. The comparison circuit 16a outputs a signal for increasing the deviation each time the level change edge of the encoder signal Se is delayed with respect to the level change edge of the reference timing signal Sr, and the encoder signal is output with respect to the level change edge of the reference timing signal Sr. Each time the Se level change edge advances, a signal for reducing the deviation is output.

  The deviation counter 18 (an example of a pool pulse detector) counts a signal output from the comparison circuit 16a and sets it as a deviation count signal St (stack pulse). Thereby, the control part 12a can count the delay of the level change edge of brushless motor drive timing signal Sb1, Sb2 with respect to the level change edge of the reference timing signal Sr, and can use it as the deviation count signal St (stack pulse signal). . The deviation counter 18 sets the output mode switching signal Sc to the H level when the deviation count signal St is 1 or more and the level change edge of the encoder signal Se is detected. As a result, when the drive control device 10a detects the next edge of the brushless motor drive timing signals Sb1 and Sb2, the drive control device 10a can control the motor 20 with the brushless motor drive timing signals Sb1 and Sb2, thereby avoiding step-out.

Further, the drive control device 10a sets the mode switching signal Sc to be output to L level when the deviation count signal St becomes 0. If the mode switching signal Sc becomes L level and the next pulse of the stepping motor drive timing signals Ss1, Ss2 is detected, the drive control device 10a has recovered the rotational position commanded by the drive pulse signal Sp. Thus, the motor 20 can be controlled again by the stepping motor drive timing signals Ss1, Ss2.
Hereinafter, operations of the comparison circuit 16a and the deviation counter 18 will be described with reference to timing charts of FIGS. 11 and 12 display an item “deviation count signal St” in addition to the same items as those in the timing charts of FIGS.
The “deviation count signal St” indicates a deviation counter.

FIG. 11 is a timing chart showing a state in which the motor 20 goes out of step in the stepping motor mode. Here, the case where the drive control device 10a is fixed in the stepping motor mode and does not switch to the brushless motor mode is shown as a comparative example.
As shown in FIG. 11, in the driving in the stepping motor mode, a rotation delay of the rotor occurs due to an excessive load or the like.

  In the vicinity of the electrical angle of 450 degrees in FIG. 11, the encoder signal Se has a falling edge. The falling edge of the reference timing signal Sr corresponding to the falling edge of the encoder signal Se is near the electrical angle of 360 degrees, and is one time before the level change edge of the immediately preceding reference timing signal Sr. That is, the level change edge of the encoder signal Se is delayed only once with respect to the level change edge of the reference timing signal Sr. At this time, the deviation count signal St of the deviation counter 18 increases from 0 to 1. Thereafter, the motor 20 is in a step-out state.

  The encoder signal Se has a rising edge near the electrical angle of 1350 degrees in FIG. The falling edge of the reference timing signal Sr corresponding to the rising edge of the encoder signal Se is in the vicinity of the electrical angle of 1170 degrees, and is two times before the level change edge of the immediately preceding reference timing signal Sr. That is, the level change edge of the encoder signal Se is delayed by two times with respect to the level change edge of the reference timing signal Sr. At this time, the deviation count signal St of the deviation counter 18 increases from 1 to 2.

FIG. 12 is a time chart showing avoidance of step-out by switching from the stepping motor mode to the brushless motor mode.
The motor 20 is driven in the stepping motor mode from the electrical angle of 0 degrees to the vicinity of the electrical angle of 740 degrees in FIG. The drive control device 10a avoids stepping out of the motor 20 by switching to the brushless motor mode when the rotor phase of the motor 20 shifts.
The deviation counter 18 counts the number of times the level change edges of the brushless motor drive timing signals Sb1 and Sb2 are delayed with respect to the level change edge of the reference timing signal Sr as a deviation count signal St (stack pulse signal).
The control unit 12a continues to select the brushless motor drive timing signals Sb1 and Sb2 and outputs the drive command signals Sm1 and Sm2 while the deviation count signal St is 1 or more.

  As shown in FIG. 12, the encoder signal Se has a falling edge in the vicinity of an electrical angle of 720 degrees. The falling edge of the reference timing signal Sr corresponding to the falling edge of the encoder signal Se is in the vicinity of the electrical angle of 630 degrees, and is one time before the level change edge of the immediately preceding reference timing signal Sr. That is, the level change edge of the encoder signal Se is delayed only once with respect to the level change edge of the reference timing signal Sr. At this time, the deviation count signal St of the deviation counter 18 increases from 0 to 1.

  When the deviation count signal St increases from 0 to 1 near the electrical angle of 720 degrees, the deviation counter 18 switches the mode at the timing of the next level change edge of the brushless motor drive timing signals Sb1 and Sb2 (near the electrical angle of 720 degrees). The signal Sc is switched to the H level. Thereby, the deviation counter 18 can suppress the hazard of the drive signals Sd1, Sd2 (drive command signals Sm1, Sm2) due to switching in the middle of the pulse, and can drive the motor 20 smoothly. Further, if the deviation count signal St is 1 or more, the deviation counter 18 sets the mode switching signal Sc to the H level. Thereby, the deviation counter 18 can prevent the motor 20 from stepping out.

After the deviation count signal St becomes 1 or more, immediately after the electrical angle of 990 degrees, the encoder signal Se has a falling edge. The falling edge of the reference timing signal Sr corresponding to the falling edge of the encoder signal Se is in the vicinity of an electrical angle of 810 degrees, and is two times before the level change edge of the immediately preceding reference timing signal Sr. That is, the level change edge of the encoder signal Se is delayed by two times with respect to the level change edge of the reference timing signal Sr. At this time, the deviation count signal St of the deviation counter 18 increases from 1 to 2.
Immediately before the electrical angle of 1350 degrees in FIG. 12, the encoder signal Se has a falling edge. The falling edge of the reference timing signal Sr corresponding to the falling edge of the encoder signal Se is in the vicinity of the electrical angle of 1170 degrees and is one time before the level change edge of the immediately preceding reference timing signal Sr. That is, the level change edge of the encoder signal Se is delayed only once with respect to the level change edge of the reference timing signal Sr. At this time, the deviation count signal St of the deviation counter 18 decreases from 2 to 1.

  Immediately before the electrical angle of 1530 degrees in FIG. 12, the encoder signal Se has a rising edge. The rising edge of the reference timing signal Sr corresponding to this rising edge is in the vicinity of the electrical angle of 1440 degrees and is the level change edge of the immediately preceding reference timing signal Sr. That is, there is no delay of the level change edge of the encoder signal Se with respect to the level change edge of the reference timing signal Sr. Therefore, the deviation count signal St of the deviation counter 18 decreases from 1 to 0.

  After the deviation count signal St decreases to 0, the reference timing signal Sr (stepping motor drive timing signal Ss1) has the next level change edge in the vicinity of the electrical angle of 1530 degrees. Thereby, the deviation counter 18 sets the mode switching signal Sc to the L level. The controller 12a controls the motor 20 by switching to the stepping motor mode, and thus controls the rotational position of the rotor.

  When the deviation count signal St decreases from 1 to 0 immediately before the electrical angle of 1530 degrees, the deviation counter 18 changes the mode at the timing of the next level change edge of the stepping motor drive timing signals Ss1 and Ss2 (near the electrical angle of 1530 degrees). The switching signal Sc is switched to the L level. Thereby, the deviation counter 18 can suppress the hazard of the drive signals Sd1, Sd2 (drive command signals Sm1, Sm2) due to switching in the middle of the pulse, and can drive the motor 20 smoothly.

  Since the control unit 12a monitors the delay of the level change edge of the encoder signal Se by the deviation counter 18, it can reliably avoid the step-out of the motor 20 and recover the rotational position commanded by the drive pulse. That is, the drive control device 10a can return to the stepping motor mode at a desired rotational position without stepping out even if a rotation delay of the rotor occurs while driving in the stepping motor mode.

  The drive control device 10a of the second embodiment counts the deviation between the reference timing signal Sr and the encoder signal Se, and determines whether or not the deviation count signal St is 0 by a simple method. The brushless motor mode can be easily switched, and the rotational position commanded by the drive pulse signal Sp can be recovered by the motor 20.

  The drive control device 10a of the motor 20 causes the deviation of the deviation count signal St (collection pulse) to overflow due to an abnormality such as a lock of the motor 20, and even if the deviation count signal St is reset, the current energization timing information is displayed. save. Therefore, the drive control device 10a of the motor 20 can constitute a system having high robustness, that is, a current maintenance capability and high resistance to disturbance.

(Modification)
The present invention is not limited to the above-described embodiment, and can be modified without departing from the spirit of the present invention. For example, there are the following (a) to (i).

(A) The position detector is not limited to the two-phase encoder 30 of the first embodiment. The position detector includes, for example, two Hall sensors that detect the rotational position of the rotor, generates a pulse signal that is synchronized with the detection signals of the two Hall sensors, and outputs the pulse signal to the control unit 12. Circuit) or the like.
(B) The type of the two-phase encoder 30 is not particularly limited, and may be, for example, an absolute encoder, an encoder with an origin signal, or the like.

(C) The type of the stepping motor is not particularly limited, and a PM type (Permanent Magnet Type), an HB type (Hybrid Type), and the like are applicable. Note that a pulse encoder capable of outputting a 90-degree phase difference signal with one sensor may be mounted on the HB type stepping motor. Thus, a magnetic encoder disk having the same number of magnetic poles as the number of steps of the motor can be attached to the motor, and the magnetic pole position of the motor can be detected and driven by the pulse encoder.

(D) The two-phase encoder 30 of the first embodiment is adjusted in advance so as to output encoder signals Se1 and Se2 of drive timing in the brushless motor mode advanced by approximately 45 degrees. However, the present invention is not limited to this, and after outputting an arbitrary encoder signal, the brushless motor drive timing generation circuit outputs the brushless motor drive timing signals Sb1 and Sb2 advanced by about 45 degrees by shifting the phase of the encoder signal. May be.

(E) The comparison circuit 16 directly compares whether or not the level change edges of the brushless motor drive timing signals Sb1 and Sb2 are delayed by a predetermined phase or more with respect to the level change edges of the stepping motor drive timing signals Ss1 and Ss2. The comparison result may be output as the mode switching signal Sc.

(F) The driving method in the stepping motor mode is not limited to full step driving, and may be micro step driving or the like. The motor is reduced in vibration by micro-step driving, and a noise-free step is possible up to 0 Hz, and a small step angle and excellent positioning are possible.

(G) At least a part of the drive control device may be an integrated circuit.

(H) At least a part of each component of the drive control device may be a software process instead of a hardware process.
(I) The method of synthesizing the encoder signal Se is not limited to exclusive OR of the encoder signals Se1 and Se2, and may be synthesized by other logical operations such as logical sum and logical product.

10, 10a Drive control device 20 Motor 30 Two-phase encoder (an example of a position detector)
11 Drive circuit (example of drive unit)
12, 12a Control unit 13 Mode selection circuit 14 Stepping motor drive timing generation circuit (STM drive timing generation circuit)
15 Brushless motor drive timing generator (BLM drive timing generator)
16, 16a Comparison circuit 17 Reference timing generation circuit 18 Deviation counter Sp Drive pulse signal (an example of drive pulse)
Sr Reference timing signal Se, Se1, Se2 Encoder signal (an example of a detection signal)
Sc mode switching signal (an example of comparison information)
Sb, Sb1, Sb2 Brushless motor drive timing signal (BLM drive timing signal)
Ss, Ss1, Ss2 Stepping motor drive timing signal (STM drive timing signal)
Sm1, Sm2 drive command signal Sd, Sd1, Sd2 drive signal (an example of drive current)
St Deviation count signal

Claims (4)

A drive unit that outputs a drive signal to each phase of the two-phase motor based on the drive command signal;
A control unit for outputting the drive command signal;
Including
The controller is
A brushless motor drive timing generation circuit that generates a brushless motor drive timing signal based on a detection signal from a position detector that detects a rotor position of the motor;
A stepping motor drive timing generation circuit that generates a stepping motor drive timing signal based on an externally input drive pulse;
A reference timing generation circuit for generating a reference timing signal obtained by dividing the drive pulse;
A comparison circuit that generates comparison information by comparing whether the level change edge of the brushless motor drive timing signal is delayed by a predetermined phase or more than the level change edge of the reference timing signal;
Based on the comparison information, a mode selection circuit that selects either the stepping motor drive timing signal or the brushless motor drive timing signal and outputs it as the drive command signal;
A deviation counter that counts the delay of the level change edge of the brushless motor drive timing signal with respect to the level change edge of the reference timing signal and sets it as a pool pulse signal;
With
If the pool pulse signal is present, the selection of the brushless motor drive timing signal is continued and output as the drive command signal,
If the pool pulse signal is lost, at the next edge of the stepping motor drive timing signal, switch to the selection of the stepping motor drive timing signal and output as the drive command signal,
The motor drive control device according to claim 1, wherein the brushless motor drive timing signal is a signal with a fixed advance value advanced in a range of 45 ° ± 12.5 °. The frequency of the detection signal output by the position detector that detects the rotor position of the motor is a multiple of the drive frequency of the brushless motor drive timing signal, and the detection signal is predetermined with respect to the back electromotive force waveform. With an advance value of
The motor drive control device according to claim 1. The frequency of the drive pulse is a frequency obtained by multiplying the drive frequency of the stepping motor drive timing signal by a multiple of a value obtained by dividing 90 degrees by the predetermined advance value.
The motor drive control device according to claim 2. A drive unit that outputs a drive signal to each phase of the two-phase motor based on the drive command signal;
A control unit for outputting the drive command signal;
A drive control method for a motor performed by a drive control device including:
The controller is
Based on a detection signal from a position detector that detects a rotor position of the motor, a brushless motor driving timing signal with an advance value fixed in a range of 45 degrees ± 12.5 degrees is generated,
A stepping motor drive timing signal is generated based on an externally input drive pulse,
Generating a reference timing signal obtained by dividing the drive pulse;
Compare whether or not the level change edge of the brushless motor drive timing signal is delayed by a predetermined phase or more than the level change edge of the reference timing signal, to generate comparison information,
Based on the comparison information, select either the stepping motor drive timing signal and the brushless motor drive timing signal, and output as the drive command signal ,
Counting the delay of the level change edge of the brushless motor drive timing signal with respect to the level change edge of the reference timing signal, as a pool pulse signal,
If the pool pulse signal is present, the selection of the brushless motor drive timing signal is continued and output as the drive command signal,
If the pool pulse signal disappears, at the next edge of the stepping motor drive timing signal, switch to the selection of the stepping motor drive timing signal and output as the drive command signal.
A motor drive control method characterized by the above.

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