JP5327667B2 - Stepping motor driving apparatus and stepping motor driving method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stepping motor drive device in which smoothness of the rotation from a low rotation zone to a high rotation zone by a micro-step drive is ensured, and an increase in power consumption, heat generation and radiation noise is reduced when it is caused because both a high-side drive element and a low-side drive element for switching excitation against excitation coils are put into a conductive state simultaneously for a moment. <P>SOLUTION: Four-phase excitation is achieved by synthesizing two-phase excitation obtained by connecting all terminals of the excitation coils of a stepping motor to either a positive electrode or a negative electrode. Furthermore, the dead time for putting both the drive elements into a cut-off state for a moment is inserted into a control command of the high-side drive element and the low-side drive element, which controls electric power supplied to the excitation coils. The length of this dead time is determined according to a voltage value applied to the excitation coils or the number of rotations of a motor rotor. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention is a drive device for driving a stepping motor having a plurality of excitation coils such as star connection, annular connection, etc., and a stepping motor drive device that changes excitation to the excitation coil in response to a rotation command pulse. And a driving method thereof.

  Generally, when driving a motor rotor of an N-phase stepping motor, a rotation command pulse is input from the outside to the stepping motor drive device, and the drive device counts the input rotation command pulse, and the count value Accordingly, the motor rotor is rotated by an angle proportional to the total number of rotation command pulses by switching the excitation to the excitation coil of the N-phase stepping motor according to the above.

  When refining the positioning resolution of the motor rotor of the N-phase stepping motor, the mechanical angle determined from the mechanical structure of the N-phase stepping motor is divided into half steps or divided into finer angles. Micro-step driving for positioning is performed.

  For example, in the stepping motor drive system described in Japanese Patent No. 3232216 (hereinafter referred to as Patent Document 1), PWM (Pulse Width Modulation) at the time of four-phase excitation is performed in a low rotation range. By changing the duty, the excitation current of each phase is adjusted stepwise to perform microstep drive (described in Patent Document 1 as minute angle drive). Then, in the high rotation range where the frequency of the rotation command pulse is shorter than the PWM frequency, the control is switched to the full step drive control by the four-phase excitation without using the PWM.

  However, as described in Patent Document 1, when switching from micro-step driving to full-step driving at the boundary between micro-step driving and full-step driving, vibration caused by a sudden change in the excitation pattern (The rotational speed of the motor rotor fluctuates.) Occurs.

  When the vibration generated at the rotational speed of this boundary part resonates with the natural frequency of the carriage controlled by the stepping motor, the amplitude increases, causing support for workpiece transfer, noise generation, etc. Cause. Therefore, in Patent Document 1, switching between micro-step driving and full-step driving is gradually performed according to the number of rotations. As a result, smoother rotation can be obtained at the boundary between microstep driving and full step driving.

  Here, in order to clarify the difference between the invention described in Patent Document 1 and the present invention described later, a figure is cited for the driving method of the stepping motor described in Patent Document 1. The outline will be described.

  First, a drive circuit for realizing the drive system of the stepping motor described in Patent Document 1 will be described with reference to FIG. The driving method of the stepping motor described in Patent Document 1 is a driving method for a five-phase stepping motor. Since Patent Document 1 does not describe a drive circuit for the 5-phase stepping motor, FIG. 2 of Japanese Patent No. 2821696 (hereinafter referred to as Patent Document 2) will be described with reference to FIG. I will decide.

  First, an excitation pattern at the time of full-step driving by four-phase excitation used in a high rotation range among driving methods of a five-phase stepping motor described in Patent Document 1 will be described.

In the case of performing full-step drive by four-phase excitation using the drive circuit shown in FIG. 27, excitation is performed by applying a voltage to each terminal of the excitation coil as follows, for example. First, the FET of the high side (described in Patent Document 1 as the upper arm) connected to the terminal A is turned on, and the low side (described as the lower arm in Patent Document 1) is driven. The FET of the element Q2 is turned off. In this way, a positive voltage of + V (V) is applied to the terminal A. At the same time, the low-side drive element Q6 is turned on, the high-side drive element Q5 is turned off, and the terminal C is connected to the negative electrode of 0 (V). Similarly, the low-side drive element Q8 is turned on, the high-side drive element Q7 is turned off, and the terminal D is connected to the negative electrode of 0 (V).

In this way, by connecting the three terminals to the power source, current flows from the terminal A via the Aφ and Bφ to the terminal C, and current flows from the terminal A via the Eφ and Dφ to the terminal D. , Aφ, Bφ, Eφ, and Dφ are excited. This excitation state will be referred to as the basic step position of step 0 * N.

  FIG. 28 shows a driving pattern at the time of full step driving for each terminal between steps 0 * N to 9 * N. FIG. 28 is a diagram shown in FIG. As shown in FIG. 28, since the positive or negative voltage is applied to the three terminals at any step angle, four-phase excitation is always performed.

  As shown in FIG. 28, by switching the excitation for each excitation coil, the electrical angle of the stepping motor is 360 ° (in the case of a 5-phase hybrid stepping motor with 50T teeth, the electrical angle is equivalent to 360 ° = mechanical angle is 7.2 °). Can be divided into 10 steps from step 0 * N to 9 * N.

  For example, when the excitation of step 0 * N is performed at the time of full step driving, no voltage is applied to the terminal B and the terminal E, and the high impedance state in which the voltage is not always controlled. It has become. That is, the high side drive element Q3 and the low side drive element Q4, and the high side drive element Q9 and the low side drive element Q10 shown in FIG. 27 are all off.

  Next, an excitation pattern at the time of microstep driving by four-phase excitation used in a low rotation range among driving methods of the five-phase stepping motor described in Patent Document 1 will be described.

  For example, when microstep driving is performed in the section E0 between step 0 * N and step 1 * N, as shown in FIG. 29, the voltage applied via the terminal B is increased according to the electrical angle. At the same time, the voltage applied via the terminal C is reduced according to the electrical angle. The current is increased or decreased by changing the PWM duty. Note that FIG. 29 is a diagram shown in FIG.

  When excitation of step 0 * N is performed at the time of microstep driving, voltages of + V (V) and 0 (V) are applied to terminal B and terminal E that are always in a high impedance state at the time of full step driving. This is realized by alternately applying a duty of 50%. Therefore, in this state, the high-side drive element Q3 and the low-side drive element Q4 and the high-side drive element Q9 and the low-side drive element Q10 FET shown in FIG. As described above, in Patent Document 1, although excitation is performed in the same step 0 * N, completely different excitation is performed in the microstep drive and the full step drive. Therefore, in the excitation switching method described in Patent Document 1, it is necessary to clearly switch between microstep drive excitation and full step drive excitation.

  An excitation method at the time of microstep drive by four-phase excitation using PWM will be described with reference to FIGS. 30 and 31. FIG. FIG. 30 is a diagram for explaining the voltage (duty) applied to the terminal A during steps 0 * N to 9 * N during microstep driving, and is a diagram shown in FIG. Note that FIG. 31 is obtained by capturing the diagram shown in FIG.

  As shown in FIG. 30, in the range of the section E0 and the section E9, the high-side drive element Q1 applies + V (V) to the terminal A with an on-duty of 100%. Therefore, the low-side drive element Q2 has an on-duty of 0% (Note that during full-step driving, as shown in FIG. 28, the on-duty of 100% or 0% in all the sections E0 to E9. Either).

  On the other hand, in the section E4 and the section E5, the high-side drive element Q1 has an on-duty of 0% with respect to the terminal A, and the low-side drive element Q2 applies a voltage of 0 (V) with an on-duty of 100%. To do.

  In the range of the section E2 and the section E7, + V (V) is applied to the terminal A with both the high-side drive element Q1 and the low-side drive element Q2 having an on-duty of 50%.

  In the range of sections E1, E3, E6, and section E8, the microstep is realized by changing the electrical angle by finely changing the duty of the high-side drive element Q1 and the low-side drive element Q2 with respect to the terminal A. doing.

  Next, a PWM waveform at the time of microstep driving by four-phase excitation will be described with reference to FIG. As shown in FIG. 31, in the range of section E0 and section E9, the high-side drive element Q1 applies a voltage of + V (V) to the terminal A with an on-duty of 100%. Therefore, the low-side drive element Q2 has an on-duty of 0%.

  In the range of the section E4 and the section E5, the high-side drive element Q1 has an on-duty of 0% with respect to the terminal A, and the low-side drive element Q2 applies a voltage of 0 (V) with an on-duty of 100%. Yes.

  In the range of the section E2 and the section E7, the high-side drive element Q1 and the low-side drive element Q2 apply + V (V) to the terminal A with 50% on-duty.

  In the range of the section E1 and the section E8, the on-duty of the driving element Q1 exceeds 50%, and the on-duty of the driving element Q2 is less than 50%. In the range of the section E3 and the section E6, the on-duty of the driving element Q1 is less than 50%, and the on-duty of the driving element Q2 exceeds 50%.

  When this stepping motor drive system is used and a sudden changeover from microstep drive to full step drive occurs at the speed of a certain motor rotor, vibration caused by a sudden change in the excitation pattern (motor rotor) The number of rotations varies).

  Therefore, in Patent Document 1, switching between micro-step driving and full-step driving is gradually performed between two threshold values using a rotation speed (referred to as a boundary portion) according to the rotation speed between the two threshold values. I tried to do it. In Patent Document 1, as shown in FIG. 32, transition speed bands TS1 to TS4 for gradually transitioning the excitation pattern according to the number of rotations of the motor rotor are provided at the boundary between the microstep driving pattern and the full step driving pattern. Provided. FIG. 32 is a diagram obtained by adding capture to FIG.

  Next, PWM waveforms in the transition speed bands TS1 to TS4 will be described with reference to FIG. FIG. 33 is obtained by adding capture to FIG. In Patent Document 1, in the transition speed band, the pulse width MW of M1 and M2 shown in FIG. 33 is lengthened according to the rotation speed of the motor rotor, so that the PWM waveform for microstep driving is used for full step driving. The transition is made to a 100% on-duty waveform.

  In the invention described in Patent Document 1, in this transition speed band, the pulse widths of M1 and M2 shown in FIG. 33 are gradually changed according to the rotation speed of the motor rotor. Thereby, since there are no discontinuous points in the change in the rotational speed, smooth rotation can be obtained from the low rotation range to the high rotation range.

  Patent Document 3 (Japanese Patent Laid-Open No. 2006-340510) discloses a motor that is generated when an excitation state during switching is continued in the transition speed band when the driving method described in Patent Document 1 is used. An invention aimed at reducing the vibration of the rotor is disclosed.

  In Patent Document 1, as shown in FIG. 32 described above, in the transition speed bands TS1 to TS4, by increasing the pulse widths of M1 and M2 in accordance with the rotational speed of the motor rotor, the PWM waveform for microsteps To the excitation waveform of 100% on-duty for full-step driving. Thus, when the excitation state is changed based only on the rotation speed of the motor rotor, if the rotation speed in the transition speed band is commanded as the command rotation speed, the excitation state in the middle of switching is continued as it is. For this reason, an unstable and undesired driving state such as vibration of the motor rotor may continue.

  Therefore, in the stepping motor control method described in Patent Document 3, in view of the problem of the driving method described in Patent Document 1, it is avoided that the excitation state during the switching of the driving mode is continued, The purpose is to drive the stepping motor more stably and smoothly.

  In the stepping motor control method described in Patent Document 3, the transition speed bands TS1 to TS4 depending on the rotational speed are abolished, and when the rotational speed of the motor rotor exceeds F1 (rpm), a predetermined time Within the TW, the pulse width of M is gradually increased to shift from the PWM waveform for microstep to the excitation waveform of 100% on-duty for full step drive.

  Further, when the rotational speed of the motor rotor falls below F2 (rpm) (F1> F2), the pulse width of M is gradually shortened within a predetermined time TW, and 100% for full-step driving. Transition from the on-duty excitation waveform to the micro-step PWM waveform is performed. Further, when the rotational speed is suddenly decreased, a function for setting the pulse width of M to 0 is added without waiting for the elapse of time TW.

  According to the invention described in Patent Document 3, it is ensured that the excitation state in the middle of switching the drive mode is always finished within the predetermined time TW, thereby avoiding continuing the excitation state in the middle of the switching. Thus, the stepping motor can be driven more stably and smoothly.

Patent Document 4 (Japanese Patent Laid-Open No. 2008-61439) discloses a stepping motor drive method that improves the resolution of microstep drive and enables ultra-low speed rotation with low vibration. The stepping motor driving method described in Patent Document 4 is a technique for further developing microstep driving to a low speed range. On the other hand, the present invention makes it possible to develop the low vibration characteristic, which is the feature of the microstep drive described in Patent Document 4, to a higher speed rotation range.
Japanese Patent No. 3232216 Japanese Patent No. 2821696 JP 2006-340510 A JP 2008-61439 A

  First, problems in the driving method of the stepping motor described in Patent Document 1 will be considered.

  As a first problem in the stepping motor driving method described in Patent Document 1, there is a problem that vibration is generated in the motor rotor when a high rotational speed is commanded during microstep driving.

  For example, as described in Paragraph No. [0004] of Patent Document 1, in the driving method of Patent Document 1, switching of the output element (switching of the driving element when the minute angle driving is performed) Interference occurs due to switching of excitation sequences by pulse signals input from an external oscillator, and the motor rotor vibrates. This is because, in the driving method described in Patent Document 1, the excitation switching interval becomes shorter as the rotational speed of the motor rotor increases during microstep driving. This is because when the PWM on / off duty switching period approaches, the PWM excitation is not completed and is terminated midway, and incomplete PWM excitation is continued. And the influence which the duty of ON / OFF by this incomplete PWM excitation brings about becomes large.

  For example, as shown in FIG. 34, rotation command pulses are input at predetermined intervals, and an address counter that counts electrical angles during microstep driving is updated in synchronization with the timing of the rotation command pulses. And On the other hand, it is assumed that the PWM period TP is slightly shorter than the interval between rotation command pulses, and the excitation coil is excited with a duty of 50%.

  Then, as shown in FIG. 34, what is supposed to be excited with a duty of 50% resets the PWM excitation cycle every time a rotation command pulse is input. It becomes a duty. If the actual duty is different, the excitation current flowing in each phase winding will be incompletely controlled, causing fluctuations in the excitation current flowing in each period, resulting in vibrations in the motor rotor. It will be. In order to reduce this influence, it is necessary to lower the number of rotations to be switched from microstep driving to full step driving and to switch at a lower number of rotations so that the interval between rotation command pulses is considerably longer than the PWM cycle TP. .

  However, when switching from micro-step drive to full-step drive at a low rotation speed, the speed fluctuation of the motor rotor is particularly noticeable at the low rotation speed, so that the fluctuation of the rotation speed of the motor rotor is further reduced. Is required.

  Usually, the PWM frequency is normally set to about 15 kHz to 20 kHz excluding the audible sound. For example, if the PWM frequency is set to 20 kHz and a microstep drive with a mechanical angle divided by 100 is performed on a commonly used 5-phase hybrid stepping motor with 50T teeth, the rotation command pulse of the angle command is The PWM frequency exceeding 20 kHz is 240 rpm (= 4 rps).

  Regarding the driving of stepping motors, the demand for higher resolution and lower vibration is increasing every year. For example, in the past, the motor rotor was required to rotate stably at a rotational speed of about 6 rpm to 60 rpm (0.1 rps to 1 rps), but in recent years, the mechanical angle of the stepping motor has been divided to 1/2000. There is a demand for smooth rotation at an ultra-low speed of 6 rps (0.1 rpm) or less while driving at a high resolution.

  Therefore, when the mechanical angle is divided into 2000 in the above example, it is 12 rpm (= 0.2 rps) that the rotation command pulse of the angle command exceeds 20 kHz of the PWM frequency. If it does so, the vibration which generate | occur | produces in a motor rotor will become large before 12 rpm before a rotation command pulse approaches PWM frequency.

  As a second problem in the stepping motor driving system described in Patent Document 1, there can be cited a problem caused by simultaneously instructing to turn on the high side driving element and turn off the low side driving element. In general, during the transition period of the on-off operation performed by the high-side drive element and the low-side drive element, there is a state where both the drive elements are simultaneously turned on. When both are turned on at the same time, the positive and negative electrodes of the power supply are directly connected (short circuit state), and a spike-like through current flows.

  FIG. 35 shows a transient state of a change in the gate voltage of the drive element when the high-side drive element is turned on and the low-side drive element is turned off simultaneously. Note that the horizontal axis of FIG. 35 represents time, and represents an embodiment using a MOS-FET (Metal Oxide Field Effect Effect Transistor) that is frequently used as a drive element.

  For example, as shown in the upper part of FIG. 35, assume that the digital output for the high-side drive element input terminal is changed from low to high and the digital output for the low-side element input terminal is dropped from high to low at the same time. Even in this case, the potential change during charging of the gate with respect to the source potential of the high-side drive element and the potential change during discharge of the gate of the low-side drive element are as shown in the lower part of FIG. Has transient characteristics.

  As shown in FIG. 35, when a command to drop the low-side element input terminal from high to low at the same time as the high-side driving element input terminal is changed from low to high, the high-side driving element and low-side driving element are simultaneously A short-circuiting time (overlapping portion) in which the short-circuit current flows when it is turned on occurs.

  Thus, the short-circuit current generated when the high-side driving element and the low-side driving element are temporarily turned on simultaneously becomes a source of wasteful power consumption in the stepping motor driving device and a source of increased heat generation. It has become. The heat generation in the stepping motor drive device reduces the reliability of the device including the drive element and accelerates aging degradation. It also becomes a factor that disturbs constant current control in the motor current control means.

  Furthermore, since the short-circuit current in this drive element flows rapidly and stops in a short time, a large radiation noise is emitted. This radiated noise is caused by electromagnetic interference such as inducing malfunctions in other circuits arranged in its own stepping motor drive device or propagating to other equipment and inducing malfunctions in other equipment. It can also be a cause.

  For the high-side drive element and the low-side drive element, drive elements having different rated current standards are selected according to the winding specifications (including differences in inductance and DC resistance) of the stepping motor to be driven and the torque. As a result, the short-circuit time during which the high-side drive element and the low-side drive element are simultaneously turned on and the short-circuit current flows also varies depending on the selected drive element. Therefore, conventionally, the corresponding stepping motor type, rated current, winding It was necessary to design the circuit configuration and circuit constants around the drive elements according to the line specifications and the like.

  In order to eliminate the short-circuit current due to the high-side drive element and the low-side drive element being in the conductive state at the same time, a sufficient period (dead time) for temporarily shutting off both the high-side drive element and the low-side drive element is sufficient. A long setting is effective.

  As described above, setting the dead time sufficiently long is an effective means for reducing the short-circuit current, but since both the high-side drive element and the low-side drive element are in the cut-off state during the dead time, the output The terminal is not connected to either the positive electrode or the negative electrode of the drive power supply (high impedance state). If the stepping motor's excitation coil terminal is in a high impedance state in a low rotation range such as during micro-step driving, the motor rotor rotation will not stabilize and vibration will increase significantly, and stop accuracy will deteriorate significantly. Will result.

  Therefore, when emphasizing the performance during microstep driving, it is preferable to set the dead time to 0. However, in order to reduce the short-circuit current and protect the driving element, the dead time should be set sufficiently long. It is required to have a conflicting setting that is preferable.

  Conventionally, in order to reduce problems caused by short-circuit current, the short-circuit current is reduced as much as possible in the circuit around the high-side drive element and the low-side drive element, and no high-impedance state is generated at the excitation coil terminal of the stepping motor. In order to do so, the circuit configuration and circuit constants have been selected with a great deal of man-hours. Therefore, the conventional stepping motor driving apparatus has been a product that has left some problems such as an increase in heat generation due to a short-circuit current and generation of radiation noise.

  In addition to the short-circuit current due to the gate voltage of the drive element shown in FIG. 35, the speed characteristics (delay) when the drive element switches from off to on and the speed when the drive element switches from on to off. There is also a problem of a slew rate in which the short circuit time increases due to characteristics (delay). Since the short circuit time due to the slew rate increases in proportion to the voltage between the source and drain of the drive element, it has a property of changing according to the drive voltage of the exciting coil.

  Independent of this, the change in the terminal voltage due to the on / off operation of the driving element induces the gate of the element, and the driving element in the off state temporarily changes to the on state, and the high side driving element and the low side driving element There is also a short-circuit current due to induction, where both are turned on simultaneously.

  For example, in the microstep driving method of the stepping motor using PWM described in Patent Document 1, as shown in FIG. 31, in the sections E1, E2, E3, E6, E7 and E8, It is repeatedly performed that ON and OFF of the low side driving element are simultaneously commanded. For example, in the excitation in the section E1, for each PWM cycle TP, the driving element Q1 is turned on and the driving element Q2 is simultaneously turned off at the time TM, and the driving element Q1 is turned off and the driving element Q2 is turned on at the time TE1. Are commanded simultaneously. In the transition period of the on-off operation performed by the drive element Q1 and the drive element Q2, a state occurs in which both the drive elements are turned on at the same time, and a spike-like through current flows here.

  The driving elements Q1 and Q2 are switched at the same time in a period E2 at time TM and time TE2, at section E3 at time TM and time TE3, at section E6 at time TM and time TE6, and at section E7 at time E7. In TM and time TE7 and in section E8, they occur at time TM and time TE8, respectively.

  On the other hand, in the case shown in FIG. 33, the drive element Q1 and the drive element Q2 are both switched simultaneously by shifting the excitation switching timing using the pulse widths of M1 and M2. Time E1 occurs at time TE1 and time TM2, time TE2 occurs at section E2, time TE3 at section E3, time TM1 and time TE6 at section E6, time TE7 at section E7, and time TE8 at section E8. Therefore, the number of times that both the drive elements Q1 and Q2 are switched simultaneously is smaller than that shown in FIG. 31, but it still exists.

  As a third problem in the driving method of the stepping motor described in Patent Document 1, there is a problem that vibration is generated in the motor rotor when switching from microstep driving to full step driving at a low rotation speed. it can.

  As described above, in recent years, there has been an increasing demand for precise positioning using a stepping motor, high rotation driving, and constant speed driving. As described in Patent Document 1, when switching to full-step driving by four-phase excitation at a relatively low rotation, the terminals of two or more exciting coils are always in a high impedance state during full-step driving. This causes a problem that the constant rotation of the motor rotor is impaired.

  As described above, when the resolution of microstep drive is improved, it is necessary to switch to full step drive by four-phase excitation in a relatively constant rotation range. Then, when switching to the full step drive in the low rotation region, there arises a problem that vibration is generated in the motor rotor.

  When the carriage or the like is driven using the stepping motor controlled in this way, there is a problem that the carriage vibrates in a low rotation range where stable driving is required.

  As a fourth problem in the driving method of the stepping motor described in Patent Document 1, there is a problem of vibration of the motor rotor that occurs when acceleration / deceleration is performed in the transition speed band.

  For example, in the transition speed zone TS1 shown in FIG. 32, step 2 in which the speed of the motor rotor is switched from the section E1 to the section E2 even though the rotational speed of the motor rotor is close to the speed range driven by the complete microstep drive pattern. * Before and after N, the waveform is such that the on-duty of the drive element Q1 decreases steeply in a staircase pattern. However, in the subsequent section E3, the on-duty gradually changes, and there is a problem that the rotational fluctuation increases rapidly only by a slight change in the rotational speed of the motor rotor.

  Therefore, when a gentle acceleration / deceleration is commanded in the transition speed range, smooth rotation cannot be obtained, and vibration is generated. When such a stepping motor drive system is used, there arises a problem that it is not suitable for a precise drive intended to transport liquids or lightweight parts. Furthermore, the effects of the motor rotor vibration, which increases when the rotation command pulse approaches the switching frequency of the PWM on / off duty, mentioned in the first problem above, are combined to produce a larger vibration. May occur.

  On the other hand, in the stepping motor control method described in Patent Document 3, even when a constant rotation speed is commanded in the transition speed band, the excitation state during the switching of the drive mode is within a predetermined time TW. Therefore, it is avoided that the excitation state during switching is continued. However, as long as microstepping is performed by combining 4-phase excitation and control that changes the duty of PWM, the influence of vibration generated when the rotation command pulse approaches the switching frequency of PWM on / off duty, In order to avoid vibration, there remains a problem that the timing for switching from microstep driving to full step driving must be executed at a low rotational speed.

  In addition, there are still problems such as an increase in power consumption due to the simultaneous command of turning on the high-side drive element and turning off the low-side drive element, problems of heat generation, and radiation noise.

  The present invention has been made in view of the above problems, and in the stepping motor drive device, the stopping accuracy (static characteristics) at a minute angle such that the resolution of the electrical angle is 1/100 or less is ensured. The purpose is to ensure smoothness of rotation (dynamic characteristics) from the low rotation range to the high rotation range.

  Further, the present invention reduces the period during which both the high-side drive element for applying the positive voltage to the coil terminal of the stepping motor and the low-side drive element for applying the negative voltage are in the conductive state simultaneously. The purpose is to reduce the short-circuit current, increase the power consumption due to this, and reduce heat generation and radiation noise.

In order to solve the above-mentioned problem, the present invention is a stepping motor driving apparatus that realizes a microstep for dividing a basic step angle α of an N-phase stepping motor into fine steps by m,
When a rotation command pulse of the N-phase stepping motor is input, the m-dividing counter that counts and outputs the number of steps in the fine step, and the number of steps in the basic step that is located in the upper digit of the m-dividing counter are counted. An electrical angle position management means having a basic step counter for outputting
In order to position the motor rotor of the N-phase stepping motor at one basic step position corresponding to the number of steps of the basic step, one excitation set for exciting a predetermined combination of two phases among the N-phase excitation coils And excitation phase combination output means for outputting an excitation combination with another excitation group for exciting another two-phase combination for positioning at another basic step position,
Excitation that determines the excitation ratio of the two excitation combinations by gradually increasing and decreasing the number of excitations or excitation times of the two excitation combinations according to the value of the m-dividing counter and the value of the basic step counter, respectively. A ratio determining means; a unit excitation cycle output means for outputting a unit excitation switching command for switching excitation for the unit excitation phases constituting the excitation set each time a predetermined unit excitation period T is counted; and the unit excitation A combination excitation cycle output means for outputting a combination excitation switching command for switching excitation according to the two excitation combinations according to the excitation ratio each time a combination excitation cycle TC constituted by an integer multiple of the cycle T is counted. When,
Each time the combination excitation switching command is output, an excitation ratio storage means for storing a new excitation ratio and an N-phase excitation coil terminal are provided, and the conduction between the excitation coil and the positive electrode of the drive power supply A high-side drive element that controls blocking, and a low-side drive element that controls conduction or blocking between the excitation coil and the negative electrode of the drive power source,
In order to switch the excitation for the unit excitation phases constituting the two excitation combinations every time the unit excitation switching command is output, using the excitation ratio stored in the excitation ratio storage means, Driving element command generating means for generating high-side command data for driving and low-side command data for driving the low-side driving element;
Dead time generating means for generating a dead time determined according to the voltage value applied to the exciting coil or the rotational speed of the motor rotor, and the high side command data and the low side command each time the unit excitation switching command is output. When a high-side command and a low-side command according to data are output, and when the unit excitation switching command is output, if the high-side command and the low-side command are switched simultaneously, the high-side command and the low-side command are switched at the time of the switching. In response to either the side command or the low side command, a new high side command or low side command in which the dead time is inserted is generated, and a high impedance state in which both the high side driving element and the low side driving element are cut off is generated. And a dead time insertion means for inserting,
The high-side drive element and the low-side drive element excite the N-phase excitation coil based on the high-side command and the low- side command, and use a new high-side command or low-side command in which the dead time is inserted. Excitation for the N-phase excitation coil is excitation for three or more phases formed based on the two excitation combinations before and after insertion of the dead time.

  In the stepping motor driving apparatus according to the present invention, four-phase excitation is realized by combining a plurality of two-phase excitations in which all the terminals of the excitation coil of the stepping motor are connected to either the positive electrode or the negative electrode of the power supply with a time shift. However, high resolution of microstep drive is realized while ensuring stop accuracy and smooth rotation during microstep drive at a resolution exceeding 1/200 of the basic step. According to this driving method, the excitation at the basic angle step can be unified in both the micro step driving and the full step driving.

  In addition to this, in the present invention, a high-side drive element that controls conduction or interruption between the excitation coil of the stepping motor and the positive electrode of the drive power supply, and a low side that controls conduction or interruption between the excitation coil and the negative electrode of the drive power supply. When switching the excitation using the drive element, when both the high-side drive element and the low-side drive element are simultaneously switched, either the high-side command or the low-side command at the time of the switching, Generate a new high-side command or low-side command in which a dead time determined according to the voltage value applied to the exciting coil or the rotation speed of the motor rotor is inserted, and both the high-side drive element and the low-side drive element are It was configured to insert a blocked high impedance state.

  By inserting a high-impedance state in which both the high-side drive element and the low-side drive element are cut off, it is possible to reduce the short-circuit time during which the high-side drive element and the low-side drive element are turned on simultaneously. Therefore, useless power consumption caused by the short-circuit current can be reduced, and useless heat generation can be reduced. By reducing this heat generation, the reliability of the device including the driving element can be improved, and the aging of the device can be reduced. Further, by reducing the short-circuit current, it is possible to reduce large radiation noise caused by this short-circuit current and reduce electromagnetic interference.

  Furthermore, the present invention provides current detection means for detecting a current flowing through the excitation coil, and current control means for controlling a voltage value of the drive power source applied to the excitation coil so that the detected current is determined within a predetermined range; The dead time generating means sets the dead time longer when the voltage value after the constant current control is high.

  In a state where the rotational speed of the motor rotor is low, the impedance of the excitation coil is also low, so the voltage value of the drive power supply applied to the excitation coil may be low. In this case, even if there is a short-circuit time in which the high-side drive element and the low-side drive element are simultaneously turned on, the short-circuit current does not take a large value. Therefore, even if the dead time is shortened, no major problem occurs. Conversely, by combining two-phase excitation with a shortened dead time, it is possible to ensure stop accuracy and smooth rotation during microstep drive. Become.

  On the other hand, when the rotational speed of the motor rotor increases, the voltage value of the drive power source applied to the excitation coil increases due to the increase in impedance of the excitation coil. Then, since the short-circuit current when the high-side drive element and the low-side drive element are turned on at the same time becomes a large value, the dead time is set to be long and wasteful power consumption and waste due to the short-circuit current are set. Heat generation and radiation noise are reduced. If the motor rotor speed is high, the importance of the smoothness of the motor rotor's rotation decreases, so even if the ratio of two-phase excitation decreases by providing a long dead time, there is a problem. Must not.

  Furthermore, the present invention provides current detection means for detecting a current flowing through the excitation coil, and current control means for controlling a voltage value of the drive power source applied to the excitation coil so that the detected current is determined within a predetermined range; The dead time generating means adds a first dead time when the voltage value after the constant current control exceeds a first threshold value, and the voltage value after the constant current control is The first dead time is subtracted when the value falls below a second threshold value that is lower than the first threshold value after exceeding the threshold value of 1.

  According to the present invention, it is possible to set the dead time in a stepwise manner in accordance with an increase in the voltage value of the drive power supply, and to set the dead time in a short manner as the voltage value of the drive power supply decreases. In addition, since there is a difference between the threshold value of the driving power source for increasing the dead time and the threshold value of the driving power source for decreasing the dead time, the voltage of the driving power source fluctuates in the vicinity of the threshold value. However, it is possible to prevent a problem that the dead time frequently fluctuates and the motor rotor speed fluctuates frequently.

  Furthermore, the present invention provides current detection means for detecting a current flowing through the excitation coil, and current control means for controlling a voltage value of the drive power source applied to the excitation coil so that the detected current is determined within a predetermined range; And the dead time generating means gradually increases the first dead time at a first increase rate when the voltage value after the constant current control exceeds a first threshold, and the constant current When the voltage value after the control exceeds the first threshold and then falls below the second threshold lower than the first threshold, the first dead time is gradually decreased at the first decrease rate. It is characterized by going.

  According to the present invention, it is possible to set the dead time in a stepwise manner in accordance with an increase in the voltage value of the drive power supply, and to set the dead time in a short manner as the voltage value of the drive power supply decreases. In addition, by gradually increasing the dead time at the first increase rate and gradually decreasing at the first decrease rate, the rotation of the motor rotor is caused by a sudden change in the excitation state of the excitation coil. The fluctuation of the number can be prevented.

  Furthermore, the present invention provides current detection means for detecting a current flowing through the excitation coil, and current control means for controlling a voltage value of the drive power source applied to the excitation coil so that the detected current is determined within a predetermined range; And the dead time generating means gradually increases the dead time at a predetermined increase rate until a time corresponding to the unit excitation period T when the voltage value exceeds the first threshold value, When it is determined that the voltage value has fallen below the second threshold value after the value has exceeded the first threshold value, the dead time is gradually decreased from the time corresponding to the unit excitation period T at a predetermined decrease rate. Features.

  According to the present invention, micro-step driving is realized in which four-phase excitation is realized by combining a plurality of two-phase excitations with time shift, but when the voltage value of the drive power source exceeds the first threshold, the unit excitation cycle T is reached. The dead time can be gradually increased to the corresponding time, and the microstep driving can be switched to the full step driving within a predetermined transition time. If it is determined that the voltage value has fallen below the second threshold value after the voltage value has exceeded the first threshold value, the dead time is gradually reduced from the time corresponding to the unit excitation period T to obtain a predetermined transition time. It is possible to switch from full-step driving to micro-step driving.

  As described above, the increase / decrease of the dead time is gradually performed and the increase / decrease of the dead time is completed within a predetermined transition time, so that the rotation of the motor rotor caused by a sudden change in the excitation state of the excitation coil The fluctuation of the number can be prevented, and the excitation with mixed dead time can be completed in a short time.

  Furthermore, the present invention is characterized in that the excitation ratio storage means stores a new excitation ratio each time the combination excitation switching command is output or the value of the basic step counter is updated. .

  According to the present invention, an excitation cycle at the time of microstep driving is ensured by performing excitation update accompanying input of a rotation command pulse based on a combination excitation switching command output every combination excitation cycle TC. And incomplete excitation can be prevented. Thus, the rotation command pulse interval is obtained when the rotation command for increasing the number of rotations of the motor rotor is input by updating the excitation accompanying the input of the rotation command pulse every combination excitation cycle TC. Even if this becomes shorter than the combination excitation cycle TC, the rotation of the motor rotor is stabilized.

  Further, by updating the excitation every time the value of the basic step counter is updated, the basic step counter update interval is larger than the interval of the combination excitation cycle TC by a rotation command to further increase the rotation speed of the motor rotor. Even in the case of shortening, by continuing the four-phase excitation by synthesizing the two-phase excitation while enlarging the steps, it is possible to secure the constant speed rotation of the motor rotor and stabilize the rotation. Further, switching from microstep driving to full step driving can be performed seamlessly, and switching from microstep driving to full step driving can be selected from a wide rotation range.

  Further, according to the present invention, the combination excitation cycle output means performs excitation by the two excitation combinations according to the excitation ratio each time a combination excitation cycle TC constituted by an integral multiple of the unit excitation cycle T is counted. A combination excitation switching command for switching is output, and each time the value of the basic step counter is updated, the combination excitation switching command is output, and counting of the combination excitation cycle TC is newly started. To do.

  According to the present invention, an excitation cycle at the time of microstep driving is ensured by performing excitation update accompanying input of a rotation command pulse based on a combination excitation switching command output every combination excitation cycle TC. By performing the renewal of the excitation accompanying the input of the rotation command pulse every combination excitation cycle TC, which can prevent incomplete excitation from occurring, the number of rotations of the motor rotor can be increased. Even when the rotation command pulse interval is shorter than the combined excitation cycle TC due to the input of the motion command, the rotation of the motor rotor is stabilized.

  Furthermore, in the present invention, the combination excitation switching command is output every time the value of the basic step counter is updated, and the counting of the combination excitation cycle TC is newly started, so the value of the basic step counter is updated. The excitation can be updated whenever it is done. As a result, even when the basic step counter update interval is shorter than the interval of the combination excitation cycle TC due to a rotation command for further increasing the rotation speed of the motor rotor, the two-phase excitation is increased while increasing the step thinning. By continuing the four-phase excitation by synthesis, it is possible to secure the constant speed rotation of the motor rotor and stabilize the rotation. Further, switching from microstep driving to full step driving can be performed seamlessly, and switching from microstep driving to full step driving can be selected from a wide rotation range.

  According to the present invention, the period during which both the high-side drive element for applying the positive voltage to the coil terminal of the stepping motor and the low-side drive element for applying the negative voltage are simultaneously turned on can be shortened. Thus, it is possible to reduce the short-circuit current of the drive element, thereby increasing power consumption, heat generation, and radiation noise due to this.

  Further, according to the present invention, in the stepping motor drive device, the resolution of the electrical angle can be reduced to 1/100 or less by enlarging the rotation speed band for performing microstep drive using four-phase excitation by combining two-phase excitation. The stop accuracy (static characteristics) at such a small angle can be ensured, and the smoothness of rotation (dynamic characteristics) from the ultra low rotation range to the high rotation range can be ensured.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail based on examples shown in the accompanying drawings.

  FIG. 1 is a block diagram showing an internal configuration of a stepping motor driving apparatus 10 that can switch the excitation mode each time a rotation command pulse is input to each excitation coil of the five-phase stepping motor 1.

  FIG. 1 shows a state in which a stepping motor driving apparatus 10 according to the present invention is connected to a 5-phase stepping motor 1 of a Pedagon connection system. In the embodiment shown in the figure, an embodiment is shown in which a Pendagon connection type five-phase stepping motor 1 is connected to perform microstep drive control. However, the present invention is a pentagon connection type stepping motor or a five-phase stepping motor. The present invention is not limited to this stepping motor, but can be applied to a star connection type stepping motor or a three-phase stepping motor. It can also be applied to a direct-acting stepping motor.

  As shown in FIG. 1, the stepping motor driving apparatus 10 according to the present invention includes a rotation command pulse CWP (Clock Wise Pulse) of the five-phase stepping motor 1 or a rotation command pulse CCWP from an external device such as a host computer. (Counter Clock Wise Pulse) is input, and excitation waveform determining means 12 for outputting high side commands and low side commands for exciting the respective excitation coils 1a to 1e of the five-phase stepping motor 1 to the drive elements TR1 to TR10. I have. Note that MOS-FETs, power transistors, and other power elements can be used as the drive elements TR1 to TR10.

  Further, the stepping motor driving apparatus 10 includes motor current control means 16 for controlling the current of the driving power supply to be supplied in accordance with the impedances of the excitation coils 1a to 1e, and excitation coils 1a to 1e and motor current control means 16 for each phase. Low-side drive element that controls conduction or interruption between the high-side drive elements TR1, TR3, TR5, TR7, and TR9, and the excitation coils 1a to 1e of each phase and the negative electrode of the drive power source. TR2, TR4, TR6, TR8, and TR10 are provided. Further, the stepping motor driving apparatus 10 includes diodes D1 to D10 that bypass electromotive forces generated by the exciting coils 1a to 1e.

  The above-described rotation command pulse CWP is a command pulse for causing the motor rotor of the five-phase stepping motor 1 to rotate forward clockwise to a predetermined rotation position, and CCWP is counterclockwise to the predetermined rotation position. This is a command pulse for reverse rotation.

  The excitation waveform determination means 12 shown in FIG. 1 counts the number of rotation command pulses input within a unit time, thereby detecting a command rotation speed detection means 12v for detecting the command rotation speed of the commanded motor rotor, The electrical angle position management means 12a that counts the number of steps of the fine step and the basic step using the input rotation command pulse, and the basic step of the motor rotor of the five-phase stepping motor 1 according to the number of steps of the basic step. Excitation phase combination output means 12b for outputting a combination of a first excitation set for positioning at a position and a second excitation set for positioning at another basic step position, the value of a frequency division step counter and a basic step counter Excitation number ratio determining means 12d (one form of excitation ratio determining means) for determining the excitation frequency ratio or excitation time ratio of the two excitation combinations according to the value of It is equipped with a door.

  The excitation waveform determining means 12 includes a unit excitation cycle output means 12h that outputs a unit excitation switching command every time a predetermined unit excitation cycle T is counted, and a combination excitation every time a predetermined combination excitation cycle TC is counted. And a combination excitation cycle output means 12c for outputting a switching command.

  Further, the excitation waveform determining means 12 stores an excitation frequency ratio storage means 12i that stores a new excitation frequency ratio or excitation time ratio every time a combination excitation switching command is output or the value of the basic step counter is updated. (One form of excitation ratio storage means), high side command data for driving the high side drive element using the excitation frequency ratio or excitation time ratio stored in the excitation frequency ratio storage means 12i, and the low side Drive element command generation means 12j for generating low side command data for driving the drive element, and a high side command for driving the high side drive element and the low side drive element using the high side command data and the low side command data And dead time insertion means 1 for switching and outputting the low-side command every time the unit excitation switching command is input. And a k.

  The excitation waveform determining means 12 includes a dead time generating means 12l for generating a dead time determined according to the voltage value applied to the excitation coil or the rotation speed of the motor rotor, and the voltage value applied to the excitation coil is the first. First threshold value judging means for detecting that the voltage value exceeds the second threshold value, and second threshold value judging means for detecting that the voltage value applied to the exciting coil is lower than the second threshold value.

  It should be noted that the functions of the excitation phase combination output means 12b, the excitation frequency ratio determination means 12d, the excitation frequency ratio storage means 12i, and the drive element command generation means 12j can be integrated and configured as a single element. However, in this embodiment, in order to facilitate explanation of each function, the configuration is described separately for each function.

  The motor current control means 16 includes a power source PS that supplies power for exciting the excitation coils 1a to 1e of the five-phase stepping motor 1, a capacitor C1 that smoothes the voltage of the power source PS, and an excitation for constant current driving. The current detection resistor 15 (current detection means) for detecting the current flowing in the coils 1a to 1e and the voltage supplied to the excitation coils 1a to 1e are adjusted by performing PWM driving that repeatedly supplies and cuts off the voltage in a short time. Transistor TR11.

  Further, the motor current control means 16 controls the transistor TR11 on and off according to the voltage generated at both ends of the current detection resistor 15, so that a predetermined current is obtained without depending on the impedance change of the exciting coils 1a to 1e. A constant current control circuit 14 that performs supply control, a diode D11 that bypasses the electromotive force generated by the exciting coils 1a to 1e, and a choke that generates an intermittent voltage generated by PWM to generate a smooth motor drive voltage. A coil L1 and a capacitor C2 are provided.

  The constant current control circuit 14 detects the current supplied to the exciting coils 1a to 1e, generates a difference between the detected current and the reference current as an error signal, and performs on / off control of the transistor TR11. As a result, the voltage supplied to the exciting coils 1a to 1e can be adjusted to control the total current for the exciting coil of the stepping motor to be a predetermined current. The voltage pulsating due to the turning on and off of the transistor TR11 is smoothed by the choke coil L1 and the capacitor C2, and supplied to the exciting coils 1a to 1e via the driving elements TR1 to TR10.

  For example, when the current flowing through the current detection resistor 15 decreases, the level of the error signal increases, so the on-time of the transistor TR11 is lengthened. Then, the voltage that has passed through the transistor TR11 is smoothed by the choke coil L1 and the capacitor C2 and becomes a high voltage, which is applied to the excitation coils 1a to 1e, so that the excitation voltage can be controlled to increase. Further, when the current flowing through the current detection resistor 15 increases, the level of the error signal decreases, so the on-time of the transistor TR11 is shortened. In this way, it is possible to perform control to reduce the voltage applied to the exciting coils 1a to 1e.

  As described above, by appropriately adjusting the excitation voltage of the five-phase stepping motor 1 using the motor current control means 16, what is the excitation period T of the first excitation group or the second excitation group output from the excitation waveform determining means 12? Irrespectively, the excitation current can be stabilized and the five-phase stepping motor 1 can be driven at a constant current. The motor current control means 16 is provided with voltage detection means for measuring the motor drive voltage and outputting the result. Instead of the embodiment shown in FIG. 1, the voltage detection means may be configured to measure the voltage value applied to the exciting coil. An analog voltage value may be used as the voltage value output from the voltage detection means, or a voltage value converted into digital voltage data using an A / D converter may be used.

  Next, excitation when the mechanical angle of the five-phase stepping motor 1 is divided into 10 for each basic step will be described with reference to FIGS.

  First, as shown in FIG. 2A, the excitation coils 1a to 1e of the five-phase stepping motor 1 adopting the pentagon connection method and the direction of the excitation current of the excitation phase ABCDEabcde are defined. Then, as shown in FIG. 2B, the relationship between the excitation phase ABCDEabcde of the five-phase stepping motor 1 and the torque vectors VA to Ve is defined.

  As shown in FIG. 2A, the excitation phase A and the excitation phase a are defined according to the direction of the current flowing through the excitation coil 1a. In the same manner, excitation phases BbCcDdEe are respectively defined according to the directions of currents flowing through the excitation coils 1b to 1e. Then, the directions of the torque vectors VA to VE and the torque vectors Va to Ve when the respective excitation phases are excited are defined as shown in FIG. As shown in FIGS. 2 (a) and 2 (b), the current flowing through the exciting coil 1a is in the opposite direction between excitation A and excitation a, and the torque vector is also in the opposite direction between VA and Va.

  Next, FIG. 3 shows a combination example of excitation phases for positioning the motor rotor at a predetermined basic step position.

  In order to simplify the expression, unit excitation when synthesizing torque vectors by multi-phase excitation by simultaneously passing excitation currents to a plurality of excitation coils of the five-phase excitation coils 1a to 1e. The combination of phases is called an excitation group. For example, a state in which two unit excitation phases of excitation phase A and excitation phase B are excited simultaneously is called two-phase excitation, and this is expressed as an excitation group (AB). Further, in order to realize pseudo four-phase excitation, the excitation group (AB) and the excitation group (CD) are synthesized in time series with the time being shifted, and the excitation group (AB-CD) is referred to as an excitation group (AB-CD). I will write it.

  In the embodiment shown in FIG. 3, when the motor rotor of the five-phase stepping motor 1 is stopped at the basic step of step = 0 * N, the four phases of the excitation phase ABCD are excited. However, since these four phases cannot be excited simultaneously using a single power source, the excitation group (BC) and the excitation group (AD) are alternately excited in time series by shifting the time, and four-phase excitation is performed. Is realized. That is, when the motor rotor is stopped at the basic step of step = 0 * N, the excitation set (BC-AD) is excited for the five-phase stepping motor 1.

  Further, as shown in FIG. 3, when the motor rotor of the 5-phase stepping motor 1 is stopped at the basic step of step = 1 * N, the excitation set (CD-BE) for the 5-phase stepping motor 1 is used. Excitation is performed. Thus, positioning in each basic step can be performed by switching the excitation from step = 0 * N to step = 9 * N.

  For example, when the basic step angle α of a 5-phase stepping motor is 0.72 °, the excitation phase is switched 10 times in the order of ABCD → BCDE → CDEa → DEab → Eabc → abcd → bcde → cdeA → deAB → eABC. Thus, the motor rotor can be rotated by 7.2 °. Further, if the step of 10 steps (0 to 9) is repeated 50 times, the motor rotor rotates 360 °, that is, just one rotation.

  Next, FIG. 4 shows another embodiment of a combination of excitation phases for positioning the motor rotor at a predetermined basic step position.

  In the embodiment shown in FIG. 4, when the motor rotor is stopped at the basic step of step = 0 * N, the excitation set (AB-CD) is excited. Further, when the motor rotor is stopped at the basic step of step = 1 * N, the excitation set (BC-DE) is excited. Thus, positioning in each basic step can be performed by switching the excitation from step = 0 * N to step = 9 * N.

  In the embodiment shown in FIGS. 3 and 4, both ends of the exciting coils 1a to 1e are always connected to the controlled potential of either the positive electrode (+) or the negative electrode (−) of the motor current control means 16. Excited like that. Thus, by performing two-phase excitation so that the terminals of the exciting coils 1a to 1e are not always opened, the overshoot of the current when switching from the previous step to the next step is reduced, and the damping characteristic Thus, it is possible to reduce vibrations and noise generated in the motor rotor.

  Next, the processing of each block constituting the excitation waveform determining means 12 shown in FIG. 1 will be described with reference to FIG.

  The excitation waveform determining means 12 shown in FIG. 5 inputs rotation command pulses of the five-phase stepping motor 1, counts the number of rotation command pulses input within a unit time, and instructs the command of the motor rotor. Command rotational speed detecting means 12v for detecting the rotational speed is provided.

  Further, the electrical angle position managing means 12a of the excitation waveform determining means 12 counts and outputs the number of steps in the basic step every time the rotation command pulse of the five-phase stepping motor 1 is input m times in order from the upper digit. A basic step counter, and an m-divided counter (hereinafter referred to as a number-divided step counter) that counts and outputs the number of steps in a number-of-times-divided step obtained by dividing the basic step angle α by m every time a rotation command pulse is input. It has.

  The number division step counter shown in FIG. 5 counts up the number of steps in the number of division steps every time the rotation command pulse CWP is inputted, and counts down the number of steps in the number of division steps every time the rotation command pulse CCWP is inputted. The value is output to the excitation frequency ratio determining means 12d. It is also possible to separately provide a counter for further subdividing the frequency division step below the frequency division step counter.

  The basic step counter corresponds to the upper digit of the number division step counter, and is configured to count up by one when the value of the number division step counter is switched from “9” to “0”. Further, the count division step counter is configured to count down by one when the value is switched from “0” to “9”. The step number of the basic step counted by the basic step counter represents the basic step position (step = 0 * N to 9 * N) shown in FIGS. 3 and 4, and the motor rotor is positioned at a predetermined step position. It is a counter for determining the combination of excitation phases.

  When the step number of the basic step is input from the basic step counter, the excitation phase combination output means 12b receives the first excitation group for positioning the motor rotor of the five-phase stepping motor 1 at one basic step position, and other A combination of excitation phases of the second excitation set for positioning to the basic step position is output. When driving a five-phase stepping motor, the number of combinations of the first excitation group and the second excitation group is twice the number N of phases of the five-phase stepping motor 1 as shown in FIGS. There are 10 types.

  The excitation phase combination output means 12b shown in FIG. 5 stores a combination of excitation phases when the five-phase stepping motor 1 is excited. When exciting the four phases of the first excitation group, an excitation group (F1-F2) for exciting the two-phase excitation group F1 and the two-phase excitation group F2 in two steps is output. Further, when exciting the four phases of the second excitation group, an excitation group (F3-F4) for exciting the two-phase excitation group F3 and the two-phase excitation group F4 in two steps is output.

  For example, when the excitation shown in FIG. 3 is performed and the basic step counter outputs “0” as the step number of the basic step (when step = 0 * N), the step of the basic step is performed. In order to realize a microstep in which the decimal number between “0” and “1” is divided into m, an excitation group (AD-BC) is output as the first excitation group and an excitation group (BE-CD) as the second excitation group. ) Is output.

  When the basic step counter outputs “1” as the step number of the basic step (in the case of step = 1 * N), the step number of the basic step is divided into “1” and “2” by m. In order to realize the microstep, the excitation group (BE-CD) is output as the first excitation group, and the excitation group (Ca-DE) is output as the second excitation group. Thereafter, similarly, the first excitation group and the second excitation group are output according to the number of steps in the basic step.

  As an element for realizing the function of the excitation phase combination output means 12b, a memory such as a ROM can be used. In that case, the electrical angle position management means 12a is configured to function as an address counter of the memory.

  The excitation frequency ratio determining means 12d gradually increases or decreases the number of times or time to excite the first excitation group according to the number of steps in the frequency division step, and gradually decreases or decreases the number of times or time to excite the second excitation group. By gradually increasing, a function of determining and outputting the excitation frequency ratio or excitation time of the first excitation group and the second excitation group is provided.

  For example, when the number of divisions in the frequency division step is set to m = 10, the number of times of exciting the first excitation group is gradually decreased from 10 to 1, and the number of times of exciting the second excitation group is set to 0. By gradually increasing up to 9 times, it has a function of changing and outputting the number of excitation times of the first excitation group and the second excitation group from 10: 0 to 1: 9. In the embodiment shown in FIG. 5, since the two-phase excitation is output twice and synthesized in order to realize the four-phase excitation, the number of excitation is 2 times × m division = 20 times (0P to 19P). It has become.

  According to the embodiment shown in FIG. 5, when the number division step counter outputs “0” as the step number of the number division step, the repetition of F1 and F2 of the first excitation group is performed as the excitation phases 0P to 19P. Assign to and output. As a result, the ratio of the number of excitations between the first excitation group and the second excitation group is set to 10: 0, and the motor rotor can be positioned at the position of the step number “0” of the basic step.

  When the number division step counter outputs “1” as the step number of the number division step, F3 and F4 of the second excitation set are substituted into the excitation phases 0P and 1P and output, and the first excitation set is output. The repetition of F1 and F2 is assigned to 2P to 19P and output. Thereby, the ratio of the number of times of excitation between the first excitation group and the second excitation group is set to 9: 1, and the motor rotor is located at a position obtained by dividing the step number “0” and “1” of the basic step into ten. Can be positioned.

  Similarly, the excitation phases 0P to 19P are determined by gradually increasing or decreasing the number of times of exciting the first excitation group according to the number of steps in the number dividing step, and gradually decreasing or gradually increasing the number of times of exciting the second excitation group. The excitation frequency ratio between the first excitation group and the second excitation group is determined and output.

  In the embodiment shown in the excitation frequency ratio determining means 12d in FIG. 5, the excitation group F1 (AD), the excitation group F2 (BC), and the excitation group F3 (BE) are described for the sake of convenience in explaining the transition of the excitation frequency ratio. ) And the excitation group F4 (CD) are alternately time-sequentially excited at different times to realize the four-phase excitation. However, as shown in FIG. Can be excited continuously. As shown in FIG. 6, by exciting each excitation group together, it is possible to reduce the number of times of excitation switching, and to reduce the heat loss and noise generated at the time of excitation switching.

  The excitation frequency ratio storage means 12i includes a first excitation group and a second excitation group that are output by the excitation frequency ratio determination means 12d each time the combination excitation switching command is output or the value of the basic step counter is updated. The excitation frequency ratio or excitation time ratio is stored.

  The unit excitation cycle output means 12h outputs a unit excitation switching command for switching excitation for the unit excitation phases constituting the excitation set every time a predetermined unit excitation cycle T is counted.

  The combination excitation cycle output means 12c is excited by two excitation combinations (for example, excitation) according to the number of times of excitation or the rate of excitation time each time the combination excitation cycle TC composed of an integral multiple of the unit excitation cycle T is counted. A combination excitation switching command for switching phases 0P to 19P.) Is output. For example, 50 μs can be used as the combination excitation cycle TC, and 2.5 μs can be used as the unit excitation cycle T.

  By repeatedly outputting the excitation phases 0P to 19P output by the excitation frequency ratio determining means 12d for each combination excitation cycle TC, it is possible to realize a microstep by dividing the basic step angle α into m.

  For example, as shown in the excitation frequency ratio determining means 12d in FIG. 5, when the number of steps in the frequency division step is 0, only the first excitation group (F1-F2) is repeatedly excited every combination excitation cycle TC. The motor rotor is positioned at the position of basic step = 0 * N. When one rotation command pulse CWP is input in this state, the value of the number division step counter is incremented by 1, and the number of steps in the number division step becomes 1. Then, within the combination excitation cycle TC, the second excitation group (F3-F4) is excited once, and the first excitation group (F1-F2) is excited nine times. By repeating the excitation at this ratio every combination excitation cycle TC, the motor rotor is positioned at a position of (basic step = 0 * N) + (number of times dividing step = 1).

  In this way, the first excitation group and the second excitation group are gradually decreased by gradually decreasing the number of times of exciting the first excitation group according to the number of steps in the number dividing step, and gradually increasing the number of times of exciting the second excitation group. The excitation frequency ratio can be changed from 10: 0 to 1: 9, and positioning according to the number of steps in the frequency division step can be performed.

  In the embodiment described above, the embodiment has been described in which the microstep is obtained by dividing the number of steps of one basic step into 10 by dividing the number of excitation times, but the present invention is limited to 10 divisions. However, 20 divisions, 40 divisions, and other division numbers may be used. Further, in addition to the number of times division, the time for exciting the first excitation group (F1-F2) is gradually decreased, and the time for exciting the second excitation group (F3-F4) is gradually increased to obtain the first excitation group. It is also possible to use microsteps by time division that change the excitation time ratio with the second excitation set.

  The drive element command generation means 12j uses the excitation frequency ratio or the excitation time ratio stored in the excitation frequency ratio storage means 12i, and uses the high-side command data for driving the high-side drive element and the low-side drive element. Generate and output low-side command data for driving.

  FIG. 7 shows a configuration example of high-side command data and low-side command data generated by the drive element command generation unit 12j. The high-side command data and low-side command data shown in FIG. 7 are obtained when the number of steps in the basic step shown in FIG. In this case, the data is 0P, 1P, 2P, 3P... In step 0 * N + (1/10) * 1).

  When the high-side command data for the high-side drive elements TR1, TR3, TR5, TR7, or TR9 is 1, these drive elements are turned on, and a positive voltage of + V (V) is applied through each output terminal. Can be output. When the low-side command data for the low-side drive elements TR2, TR4, TR6, TR8, or TR10 is 1, these drive elements are turned on, and each output terminal can be connected to the negative electrode of 0 (V). Although not shown in FIG. 7, when both the high-side command data and the low-side command data are 0, the output terminal is not connected to either + V (V) or 0 (V). It becomes.

  The first threshold value determination unit 12m acquires the voltage value of the driving power source applied to the exciting coil from the voltage detection unit of the motor current control unit 16, and compares it with a predetermined first threshold value. If the voltage value of the drive power supply becomes higher than the first threshold value, the first rotational speed information indicating that is stored and the first rotational speed information is also output to the dead time generating means 12l. When the dead time generating unit 121 acquires the first rotation speed information, the dead time generating unit 121 generates and outputs a first dead time instead of the second dead time output to the dead time inserting unit 12k.

For example, 2.5 μs is set as the unit excitation cycle T, and the motor current control means 16 can output 3 to 23 (V) as a voltage to be applied to the excitation coil. When the voltage value exceeds 10 (V) set as the first threshold value, the dead time generating unit 121 outputs 50 ns as the first dead time. Note that 0 ns may be used as the second dead time value, or an initial value such as 10 ns may be used. The dead time generating unit 12l can use a configuration that outputs an analog dead time or a configuration that includes a dead time counter and outputs the dead time as a numerical value.

  The second threshold value determination unit 12n acquires the voltage value of the driving power source applied to the exciting coil and compares it with a predetermined second threshold value. The value of the second threshold is set to a value lower than the first threshold, thereby providing hysteresis when setting the dead time according to the voltage value. If the voltage value of the drive power supply is lower than the second threshold value, the second rotation speed information indicating that is output to the first threshold value judging means 12m. When the first threshold value determination unit 12m acquires the second rotation number information, the first threshold value determination unit 12m resets the stored first rotation number information and outputs the second rotation number information to the dead time generation unit 12l.

  For example, when the voltage value of the drive power supply falls below 9 (V) set as the second threshold value, the second rotation speed information indicating that is output to the first threshold value judging means 12m. The first threshold value determination unit 12m that has acquired the second rotation number information resets the stored first rotation number information and outputs the second rotation number information to the dead time generation unit 12l.

  When the dead time generating unit 12l acquires the second rotation speed information, a second dead time (for example, 0 ns) is generated instead of the first dead time (for example, 50 ns) output to the dead time inserting unit 12k. Output. When the voltage applied to the excitation coil of the N-phase stepping motor 1 is high, generally, the time during which the high-side drive element and the low-side drive element are turned on at the same time becomes longer, so that the dead time depends on the voltage value applied to the excitation coil. A long time should be set.

  Each time the unit excitation switching command is output from the unit excitation cycle output unit 12h, the dead time insertion unit 12k outputs a high side command and a low side command corresponding to the high side command data and the low side command data.

  The drive elements TR1 to TR10 excite the respective excitation coils 1a to 1e of the five-phase stepping motor 1 in accordance with the high side command and the low side command acquired from the dead time insertion unit 12k.

  An example of the high-side command and the low-side command output from the dead time insertion unit 12k described above is shown in the timing chart of FIG.

  The high-side command and the low-side command shown in FIG. 8 are output by switching the high-side command and the low-side command every time the unit excitation switching command is output using the high-side command data and the low-side command data shown in FIG. It is a figure which shows the state to perform, and is a command when not inserting a dead time.

  In the example shown in FIG. 8, at time TF0, the high-side drive element TR5 and the low-side drive element TR6 of OUT3 are switched simultaneously. In this case, a gate-on overlapping portion as shown in FIG. 35 occurs and a short-circuit current due to the slew rate of the drive element increases. Similarly, at time TF1, the high-side drive elements TR1 and TR5 and the low-side drive elements TR2 and TR6 are simultaneously switched. At time TF2, the high side drive element TR7 and the low side drive element TR8 are simultaneously switched. At times TF3 and TF4, the high side drive elements TR1 and TR7 and the low side drive elements TR2 and TR8 are simultaneously switched.

  When the voltage of the drive power supply is low, the short-circuit current generated by switching the high-side drive element and the low-side drive element at the same time is not a problem, but when the voltage of the drive power supply is increased (for example, five-phase The short-circuit current in the case where the rotational speed of the motor rotor of the stepping motor 1 is increased) may cause problems such as increased power consumption, reduced device reliability due to heat generation, and emission noise. become.

  Therefore, in the present invention, when the high-side drive element and the low-side drive element are switched at the same time, a high-impedance state in which both the drive elements are cut off for a period of time is inserted. Thereby, it is possible to reduce the short-circuit current due to the gate-on overlapping portion as shown in FIG. 35 and to reduce the short-circuit current due to the slew rate of the drive element. In addition, it is possible to prevent an increase in power consumption, prevent heat generation, prevent a problem that the reliability of the device is lowered, and reduce generated radiation noise.

  If a high impedance state in which both the high-side drive element and the low-side drive element are cut off is inserted by inserting a dead time, the stop accuracy at the time of microstep driving deteriorates or the motor rotation of the five-phase stepping motor 1 When the number of rotations of the child is low, the rotation becomes unstable and vibration occurs. Therefore, when the rotation speed of the motor rotor is low and the voltage of the drive power supply is low, it is preferable that the dead time is short in order to improve stop accuracy and stabilize the rotation of the motor rotor.

  FIG. 9 shows an example of a timing chart of the high side command and the low side command in which the dead time DT is inserted by the dead time inserting means 12k. FIG. 9 shows the case of the combination 1 of the two-phase excitation shown in FIG. 3 and the high-side command including the dead time DT inserted when the number of steps in the basic step = 0 and the number of steps in the number dividing step = 1. It is a figure showing the low side command.

  As shown in FIG. 9, when the unit excitation switching command is output at time TF0, when the high-side drive element TR5 and the low-side drive element TR6 are simultaneously switched, the high-side command for the high-side drive element TR5 is switched. Insert an on-delay dead time DT. By inserting the dead time DT, the output terminal OUT3 is in a high impedance state during this period, so that the excitation group that is actually excited during the dead time DT is a three-phase BCE.

  The torque vector of the excitation set (BCE) is 22.4 ° when calculated with reference to FIG. The torque vector of this excitation group (BCE) is a torque vector located between the torque vector 36 ° in the excitation group (BC) immediately before time TF0 and the torque vector 0 ° in the excitation group (BE) up to time TF1. It becomes. Thus, since the torque vector obtained by inserting the dead time DT becomes a torque vector located between them, there is no problem that fluctuations appear in the rotational speed of the motor rotor by inserting the dead time DT. .

  At the next time TF1, the four-phase excitation of the excitation set (BCDE) is performed by inserting an on-delay dead time DT into the low-side drive elements TR2 and TR6. The torque vector of the excitation set (BCDE) is 0 °, which is equal to the torque vector 0 ° in the excitation set (BE) up to time TF1 and the torque vector 0 ° in the excitation set (CD) up to time TF2. Therefore, there is no problem that the rotational speed of the motor rotor changes due to the insertion of the dead time DT.

  At the next time TF2, the three-phase excitation of the excitation set (ACD) is performed by inserting an on-delay dead time DT into the low-side drive element TR8. The torque vector of the excitation group (ACD) is 13.6 °, and it is between the torque vector 0 ° in the excitation group (CD) until time TF2 and the torque vector 36 ° in the excitation group (AD) until time TF3. It is what is located. Therefore, there is no problem that the rotational speed of the motor rotor changes due to the insertion of the dead time DT.

  At the next time TF3, four-phase excitation of the excitation group (ABCD) is performed by inserting an on-delay dead time DT into the high-side drive elements TR1 and TR7. The torque vector of the excitation group (ABCD) is 36 °, which is equal to the torque vector 36 ° in the excitation group (AD) up to time TF3 and the torque vector 36 ° in the excitation group (BC) up to time TF4. Therefore, there is no problem that the rotational speed of the motor rotor changes due to the insertion of the dead time DT.

  Similarly, when the high-side command and the low-side command are switched at the same time, the dead time for setting the output terminal to the high-impedance state with respect to either the high-side command or the low-side command at the time of switching. A new high-side command or low-side command in which is inserted is generated.

  In the present invention, the dead time is increased as the voltage value of the drive power supply increases. Therefore, the dead time becomes longer as the rotational speed of the motor rotor increases. In general, in a stepping motor drive device, when the rotation speed of the motor rotor increases, a process of switching from micro-step drive to full-step drive in which excitation is performed for each basic angle step at any timing is performed.

  In the embodiment shown in FIG. 9, an embodiment in which an on-delay dead time DT is inserted in a portion where the high-side command or the low-side command changes from 0 to 1 is shown. In addition, by changing the high side command or the low side command from 1 to 0 without waiting for the unit excitation period T to elapse, the dead time DT for shutting off both the high side drive element and the low side drive element is set. It can also be inserted.

  Next, consider the case where the dead time DT is gradually extended from the state shown in FIG. 9 as the rotational speed of the motor rotor increases. It is also possible to extend the dead time DT from the state shown in FIG. 9 to the dead time DT = T. In that case, the torque vectors are 22.4 °, 0 °, 13.6 °, 36 °, 36 °, etc., and the original torque vector of dead time DT = 0 is 0 °, 0 °, 36 °, 36 °. It will be slightly different from…. If the problem due to the difference in torque vector becomes prominent, the problem can be avoided by switching from micro-step driving to full-step driving.

  FIG. 10 shows the case of the combination 1 of the two-phase excitation shown in FIG. 3, in which the full step drive with the step number of basic steps = 0 is performed and the dead time DT = T / 2 is inserted and the high side command and low side An example of a command timing chart is shown.

  As shown in FIG. 10, the torque vector does not change even when the excitation phase (AD-BC) is excited and the dead time DT is inserted to perform the excitation phase (ABCD) four-phase excitation. . Therefore, in the basic step, even if the dead time DT is set longer and the dead time DT = T, no problem occurs.

  In other words, the dead time DT is increased in order to reduce the short-circuit current flowing through the high-side drive element and the low-side drive element as the rotational speed of the motor rotor increases, and by switching to full-step drive, It is possible to shift to full-step driving with four-phase excitation.

  When full-step driving is performed, the combination of excitations related to the number-of-times division step or the like is not necessary, so that two-phase excitation that enables quiet operation with low vibration until the basic step update period reaches 2 × T ( Full step drive can be performed by excitation in which all terminals of the excitation coil of the stepping motor are connected to either the positive electrode or the negative electrode of the power source. In addition, when switching to full-step driving by four-phase excitation, normal high-speed rotation can be performed even when the basic step update period is further shortened.

  9 and 10 described above, the combination 1 of the two-phase excitation shown in FIG. 3 is used, and the excitation set (AD-BC) and the excitation set (BE) when the step number of the basic step is 0. -CD) was explained. FIG. 11 shows the excitation group in the step number of each basic step from Step 0 * N to Step 9 * N when the two-phase excitation combination 1 is used. As shown in FIG. 11, by inserting the dead time DT into the high-side command or the low-side command, three-phase excitation or four-phase excitation is formed between the two-phase excitations.

  Next, the combination 2 of the two-phase excitation shown in FIG. 3 will be described. 9 and 10, the two-phase excitation combination 1 shown in FIG. 3 has been described. Similarly, in the case of the two-phase excitation combination 2, excitation with the dead time DT inserted can be performed. FIG. 12 shows the high-side command and the low-side command in which the dead time DT is inserted in the case of the combination 2 of the two-phase excitation when the number of steps in the basic step = 0 and the number of steps in the number dividing step = 1. FIG.

As shown in FIG. 12, when the unit excitation switching command is output at time TF0, if the high-side drive element TR1 and the low-side drive element TR2 are switched simultaneously, the high-side command for the high-side drive element TR1. Insert an on-delay dead time DT. By inserting the dead time DT, the output terminal OUT1 becomes the high impedance state, excitation set actually excited is the three-phase BC D.

The torque vector of the excitation group (BC D ) is 18 ° when calculated with reference to FIG. The torque vector of the excitation set (BC D ) is a torque vector between the torque vector 0 ° in the excitation set (CD) immediately before time TF0 and the torque vector 36 ° in the excitation set (BC) up to time TF1. Therefore, there is no problem that the rotational speed of the motor rotor changes due to the insertion of the dead time DT.

  At the next time TF1, by inserting an on-delay dead time DT into the low-side drive element TR2 and the high-side drive element TR5, four-phase excitation of the excitation set (BCDE) is performed. The torque vector of the excitation group (BCDE) is 0 °, and the intermediate torque between the torque vector 36 ° in the excitation group (BC) until time TF1 and the torque vector -36 ° in the excitation group (DE) until time TF2. It becomes a vector. Therefore, there is no problem that the rotational speed of the motor rotor changes due to the insertion of the dead time DT.

  At the next time TF2, the five-phase excitation of the excitation set (ABCDE) is performed by inserting an on-delay dead time DT into the high-side drive element TR1 and the low-side drive elements TR6 and TR8. The torque vector of the excitation group (ABCDE) is 18 °, which is exactly halfway between the torque vector -36 ° in the excitation group (DE) up to time TF2 and the torque vector 72 ° in the excitation group (AB) up to time TF3. It is what is located. Therefore, there is no problem that the rotational speed of the motor rotor changes due to the insertion of the dead time DT.

  At the next time TF3, an on-delay dead time DT is inserted into the low-side drive element TR2 and the high-side drive element TR7 to perform four-phase excitation of the excitation set (ABCD). The torque vector of the excitation group (ABCD) is 36 °, and is located just in the middle between the torque vector 72 ° in the excitation group (AB) up to time TF3 and the torque vector 0 ° in the excitation group (CD) up to time TF4. To do. Therefore, there is no problem that the rotational speed of the motor rotor changes due to the insertion of the dead time DT.

  Similarly, when the high-side command and the low-side command are switched at the same time, the dead time for setting the output terminal to the high-impedance state with respect to either the high-side command or the low-side command at the time of switching. A new high-side command or low-side command in which is inserted is generated.

  Similarly to the above-described case, it is possible to extend the dead time DT from the state shown in FIG. 12 and extend to the dead time DT = T. In this case, the torque vectors are 22.4 °, 0 °, 18 °, 36 °, 36 °, etc., and the original torque vectors 36 °, −36 °, 72 °, 0 °, etc. with dead time DT = 0. Will be slightly different. If the problem due to the difference in torque vector becomes prominent, the problem can be avoided by switching from micro-step driving to full-step driving.

  FIG. 13 shows the timing chart of the high-side command and the low-side command in the case of the combination 2 of the two-phase excitation, in which the full step drive with the step number of basic steps = 0 is inserted and the dead time DT = T / 2 is inserted. An example is shown.

  As shown in FIG. 13, even when the excitation phase (AB-CD) is excited and the dead time DT is inserted to perform the excitation phase (ABCD) four-phase excitation, the torque vector changes to the synthesized torque vector. Does not occur. Therefore, in the basic step, even if the dead time DT is set longer and the dead time DT = T, no problem occurs. In other words, the dead time DT is increased in order to reduce the short-circuit current flowing through the high-side drive element and the low-side drive element as the rotational speed of the motor rotor increases, and by switching to full-step drive, It is possible to shift to full-step driving with four-phase excitation.

  12 and 13 described above, the combination 2 of the two-phase excitation shown in FIG. 4 is used, and the excitation group (AB-CD) and the excitation group (BC) when the number of steps in the basic step = 0. -DE) has been described. FIG. 14 shows the excitation group in the step number of each basic step from Step 0 * N to Step 9 * N when the two-phase excitation combination 2 is used. As shown in FIG. 14, by inserting the dead time DT into the high-side command or the low-side command, three-phase excitation, four-phase excitation, or five-phase excitation is formed between the two-phase excitations.

  When full-step driving is performed, the combination of excitations related to the number-of-times division step or the like is not necessary, so that two-phase excitation that enables quiet operation with low vibration until the basic step update period reaches 2 × T ( Full step drive can be performed by excitation in which all terminals of the excitation coil of the stepping motor are connected to either the positive electrode or the negative electrode of the power source. In addition, when switching to full-step driving by four-phase excitation, normal high-speed rotation can be performed even when the basic step update period is further shortened.

[Embodiment for setting a plurality of dead times]
In the embodiment described above, when the voltage value of the drive power supply exceeds the first threshold, the dead time insertion unit 12k adds the first dead time to either the high side command or the low side command, The embodiment has been described in which the first dead time is subtracted when the voltage value of the drive power source exceeds the first threshold value and then falls below the second threshold value that is lower than the first threshold value. More types of dead times can be set according to the voltage value of the drive power supply.

  For example, as shown in FIG. 15, a plurality of dead times DT can be set according to the voltage value of the drive power supply. In the embodiment shown in FIG. 15, the dead time DT = 0 ns when the voltage value of the driving power supply is less than 10 (V), and the dead time DT when the voltage value of the driving power supply rises to 10 (V) or more. = 50 ns is set. Thereafter, when the voltage value of the drive power supply drops below 9 (V), the dead time DT = 0 ns is set.

  Further, when the voltage value of the driving power source rises to 12 (V) or more, the dead time DT = 100 ns is set, and when the voltage value of the driving power source rises to 14 (V) or more, the dead time DT = 500 ns. When the voltage value of the driving power supply rises to 16 (V) or more, the dead time DT = 1000 ns is set, and when the voltage value of the driving power supply rises to 20 (V) or more, the dead time DT = 2500 ns (= 2.5 μs = T) is set.

  After that, when the voltage value of the driving power supply falls below 17 (V), the dead time DT = 1000 ns is set. When the voltage value of the driving power supply falls below 13 (V), the dead time DT is set. = 500 ns is set, and when the voltage value of the driving power supply falls below 12 (V), the dead time DT = 100 ns is set, and when the voltage value of the driving power supply falls below 10 (V) , Dead time DT = 50 ns is set.

  As shown in FIG. 15, by setting a plurality of dead times DT according to the voltage value of the drive power supply, it is possible to prevent an increase in short circuit current due to the slew rate of the drive element. When the rotation speed of the motor rotor is low, the rotation of the motor rotor can be stabilized by shortening the dead time DT and approaching the two-phase excitation. Further, when the motor rotor is stopped, two-phase excitation with good stopping accuracy can be performed.

[Embodiment in which dead time is continuously changed]
Further, as shown in FIG. 15, instead of increasing the dead time DT stepwise according to the voltage value of the driving power source, the dead time DT is continuously increased according to the voltage value of the driving power source as shown in FIG. It can also be configured to increase. In this case, without using the first threshold value judging means 12m and the second threshold value judging means 12n shown in FIG. 5, the dead time generating means 12l directly outputs the voltage value of the drive power output from the motor current control means 16. This can be realized by obtaining and outputting the dead time DT corresponding to the voltage value of the driving power source to the dead time inserting means 12k.

[Embodiment in which dead time is set in accordance with the rotational speed of the motor rotor]
In the above embodiment, the short-circuit current due to the gate-on overlapping portion generated when the high-side drive element and the low-side drive element are switched at the same time and the short-circuit current due to the slew rate of the drive element are reduced. In order to make this happen, the embodiment in which the dead time DT is set according to the voltage value of the drive power supply has been described. In this way, by setting the dead time DT according to the voltage value of the drive power supply, it becomes possible to handle a plurality of types of stepping motors with different winding specifications with the same stepping motor driving device. The versatility of the stepping motor driving device can be improved.

  If a stepping motor driving device dedicated to a specific stepping motor is used, instead of setting the dead time DT according to the voltage value of the driving power supply, for example, the command rotational speed output by the command rotational speed detection means 12v, or The dead time DT can be set according to the rotation speed of the stepping motor.

  For example, as shown in FIG. 17, the relationship between the number of rotations of the motor rotor and the voltage value of the drive power supply differs depending on the type of stepping motor. FIG. 17 is a diagram illustrating the relationship between the rotation speed (rpm) of the motor rotor and the voltage value (V) of the drive power source in each of the stepping motors A, B, and B. . As shown in FIG. 17, by setting the dead time DT according to the voltage value of the drive power supply, it becomes possible to cope with a stepping motor having a plurality of types of winding specifications, and the versatility of the stepping motor drive device can be increased. Can be improved.

  As shown in FIG. 17, in the case of the stepping motor C having a small inductance, the voltage value of the drive power supply at a predetermined rotational speed is lower than that of the stepping motor A having a large inductance, and therefore the short circuit current is also small. Therefore, when the stepping motor C having a small inductance is driven using the stepping motor driving apparatus according to the present invention, the rotation speed region where the dead time DT = 0 can be widened. Therefore, when the stepping motor C having a small inductance is driven, a smooth rotation can be obtained up to a higher rotation speed. Furthermore, since the two-phase excitation including the dead time DT can be performed up to a higher rotation, the number of rotations in which a quiet operation can be performed with a low vibration can be expanded.

[Embodiment in which micro step driving and full step driving are switched by setting dead time]
FIG. 18 shows an embodiment in which the micro step driving and the full step driving are switched by setting the dead time DT according to the rotation speed of the motor rotor. In the embodiment shown in FIG. 18, when the motor rotor is accelerating and the rotation speed of the motor rotor is less than 1400 rpm, the dead time DT is set to 0 ns, and the rotation speed of the motor rotor is increased to 1400 rpm or more. In this case, dead time DT = T = 2500 ns is set. And when the rotation speed once increased to 1400 rpm or more falls below 1000 rpm, the dead time DT which was 2500 ns is set to 0 ns.

  This dead time DT = 2500 ns is the same value as the unit excitation period T = 2.5 μs. Therefore, when the dead time DT is set to 2500 ns, it is switched to full-step driving by four-phase excitation (see FIG. 10 or FIG. 13).

  When the dead time DT is changed from 0 ns to 2500 ns, the dead time generating unit 12l gradually increases the dead time at a predetermined increase rate (for example, 100 ns / T) until the time corresponding to the unit excitation period T. And good. By gradually changing the dead time in this way, it is possible to prevent the excitation state of the excitation coil from changing suddenly and to prevent fluctuations in the rotational speed of the motor rotor. When the dead time is gradually increased at an increase rate of 100 ns / T, the microstep driving is switched to the full step driving during 25 cycles × combination excitation cycle TC = 1250 μs.

  Similarly, when the dead time DT is changed from 2500 ns to 0 ns, the dead time generating means 12l gradually reduces the dead time at a predetermined increase rate (for example, 200 ns / T) until the time corresponding to the unit excitation period T. It is good to let it go. When the dead time is gradually reduced at a reduction rate of 200 ns / T, the full-step drive is switched to the micro-step drive during 13 cycles × combination excitation cycle TC = 650 μs.

[Embodiment in which dead time is changed using a predetermined dead time rate]
When changing the dead time DT to be inserted into the high-side command or the low-side command at a certain rotational speed, increase or decrease the dead time DT at a predetermined dead time rate as described above. Can do.

  For example, as shown in FIG. 19, when the voltage value of the drive power supply is less than 16 (V), an increase rate of 50 (ns / T) is set as the dead time rate. When the motor rotor is accelerating and the voltage value of the drive power supply rises to 16 (V) or more, the dead time rate is set to an increase rate of 100 (ns / T).

  Further, when the motor rotor decelerates once the voltage value of the drive power supply has increased to 16 (V) or more, a decrease rate of 200 ns / T is set as the dead time rate. Furthermore, when the motor rotor decelerates and the voltage value of the drive power supply falls below 13 (V), the dead time rate set to 200 (ns / T) is reduced by 100 (ns / T). Set to rate.

  Next, a case where the setting of the dead time DT shown in FIG. 15 and the setting of the dead time rate shown in FIG. 19 are used in combination will be considered. When the voltage value of the drive power supply rises from 13.9 (V) to 14.1 (V), in the first unit excitation cycle T, with respect to the high-side command or the low-side command inserted so far, A dead time DT = 150 ns obtained by adding 50 ns to the dead time DT = 100 ns is inserted. In the next unit excitation period T, a dead time DT = 200 ns obtained by further increasing the dead time by 50 ns is inserted. Then, the value of the dead time DT is increased by 50 ns for each unit excitation cycle T, and the maximum value 500 ns of the dead time DT is inserted after the eighth unit excitation cycle T.

  Further, when the rotation speed of the motor rotor rises and the voltage value of the drive power supply rises from 15.9 (V) to 16.1 (V), the dead time DT = 500 ns inserted so far The dead time DT = 600 ns increased by 100 ns is inserted into the high side command or the low side command, and the dead time DT = 700 ns further increased by 100 ns is inserted in the next unit excitation period T. In this way, the dead time DT is sequentially increased by 100 ns for each unit excitation period T, and the maximum value 1000 ns of the dead time DT is inserted in the unit excitation periods T after the fifth time.

In addition, when the voltage value of the drive power source once increased to 16 (V) or more and less than 20 (V) falls to 12.9 (V), it has been inserted so far in the first unit excitation period T. The dead time DT = 800 ns obtained by subtracting 200 ns from the dead time DT = 1000 ns is inserted into the high side command or the low side command, and the dead time DT = 600 ns obtained by further subtracting 200 ns is inserted in the next unit excitation period T. To do. In the third and subsequent unit excitation periods T, 500 ns is inserted as the dead time DT.

  The dead time increase rate and decrease rate can be set to different values as described above, or can be set to the same value. In addition to changing the increase rate or decrease rate of the dead time according to the voltage value of the drive power supply, it can also be changed according to the rotation speed of the motor rotor. Further, the increase rate or decrease rate of the dead time can be changed according to the acceleration or deceleration of the motor rotor. In addition to determining the dead time increase rate or decrease rate, the change time for changing the dead time is determined according to the voltage value of the drive power supply, the rotation speed of the motor rotor, the acceleration or deceleration of the motor rotor, A dead time rate can also be set based on the change time. These dead time values, dead time rate values, various threshold values, and other setting items may need to be changed according to the type of stepping motor and winding specifications. It is preferable to configure the function setting so that it can be changed.

  Moreover, the voltage value of the drive power supply and the increase / decrease in the dead time DT depending on the rotation speed of the motor rotor may be used in combination. For example, in this case, the setting for increasing the dead time DT may be given priority over the setting for decreasing the dead time DT.

For example, when the setting of the dead time DT determined by the number of revolutions of the motor rotor is 0 ns, but the setting of the dead time DT determined by the voltage value of the driving power source of the exciting coil is 2500 ns. Is preferably performed by inserting the longer dead time DT = 2500 ns.

Conversely, when the dead time DT determined by the voltage value of the drive power source of the exciting coil is 1000 ns , the dead time DT determined by the rotation speed of the motor rotor is 2500 ns. The excitation with the longer dead time DT = 2500 ns dead time inserted may be performed.

[Embodiment in which micro-step driving is switched to full-step driving within a predetermined transition time]
In the above, the embodiment in which the dead time DT is gradually increased or decreased by determining the dead time rate has been described. Instead of this, a transition time for gradually increasing or decreasing the dead time DT may be determined in advance, and the increase or decrease of the dead time DT may be completed within the transition time.

  For example, when switching between micro-step driving and full-step driving under the conditions shown in FIG. 18 and setting 2500 μs as the transition time during acceleration, the increasing rate is increased rate = unit excitation cycle T. / (Transition time during acceleration / combination excitation cycle TC) = 2.5 μs / (2500 μs / 50 μs) = 2.5 μs / 50 = 50 ns / T. In other words, by gradually increasing the dead time DT at an increase rate of 50 ns / T, the four-phase excitation of the dead time DT = T from the micro step driving by the two-phase excitation of the dead time DT = 0 within the transition time of 2500 μs. Can be switched to full-step driving.

  When 1250 μs is set as the transition time during deceleration, the decrease rate is as follows: decrease rate = unit excitation cycle T / (transition time during deceleration / combination excitation cycle TC) = 2.5 μs / (1250 μs / 50 μs) = 2.5 μs / 25 = 100 ns / T. That is, by gradually decreasing the dead time DT at a decreasing rate of 100 ns / T, two-phase excitation with dead time DT = 0 from full-step driving by four-phase excitation with dead time DT = T within the transition time of 1250 μs. Can be switched to microstep driving.

  In this way, by gradually switching between micro-step driving and full-step driving within a predetermined transition time, fluctuations in the rotational speed of the motor rotor due to sudden changes in the excitation state of the exciting coil are prevented. In addition, the excitation by microstep driving and the excitation in which the dead time DT is mixed can be completed in a short time. Therefore, the switching between the micro step driving and the full step driving can be smoothly finished.

  Further, not only when switching between micro-step driving and full-step driving, but also when changing dead time DT according to the voltage value of the drive power supply and the rotation speed of the motor rotor, the transition time is determined and dead time DT is determined. Can be configured to gradually increase or decrease. As described above, the transition time can be set to a different value between acceleration and deceleration, or the same value. Also, different transition times can be set according to the voltage value of the driving power source, the rotation speed of the motor rotor, and the rate of change thereof.

[Embodiment using basic step synchronous update 1]
Next, excitation switching timing when the motor rotor of the five-phase stepping motor 1 is rotating will be described with reference to FIGS. 20 and 21. FIG. Here, an excitation switching method for switching excitation every predetermined combination excitation cycle TC is referred to as excitation cycle synchronization update. In addition to this, as will be described below, an excitation switching method in which excitation is updated from the middle of the combined excitation cycle TC as the basic step counter is updated will be referred to as basic step synchronization update 1. 20 and FIG. 21 shows a case where the number of basic steps = 10 and the number of times of division m = 10, as shown in FIG.

  20 and 21 show the change in the value of the number division step counter (represented by a two-digit numerical value) when the rotation command pulse CWP is input, and the upper order of the number division step counter. Changes in the value of the basic step counter corresponding to this digit (represented by a two-digit numerical value), the combination excitation switching command output at each combination excitation cycle TC, and the excitation frequency ratio storage means 12i. The step position (represented by a four-digit numerical value) is shown with the horizontal axis representing time. The excitation number ratio storage means 12i stores the first excitation group and the second excitation group and the excitation number ratio, but here, for convenience of explanation, the value of the number division step counter and the basic step counter And the value of.

  Of these figures, FIG. 20 shows a change in the step position when the rotation command pulse interval is about 1 / 7.5 of the combined excitation cycle TC. FIG. 21 shows a change in the step position when the update interval of the basic step counter is shorter than the combination excitation cycle TC.

  First, the excitation switching timing using the basic step synchronization update 1 when the rotation command pulse interval is about 1 / 7.5 of the combined excitation cycle TC will be described with reference to FIG. For example, when the 5-phase stepping motor 1 with a mechanical angle of 7.2 ° is used and the basic step number = 10, the number of divisions m = 10, and the combination excitation cycle TC = 50 μs, the state shown in FIG. The rotor is rotating at about 30 rps (1800 rpm).

  As shown in FIG. 20, when the rotation command pulse CWP is input, the value of the frequency division step counter is updated at the rising edge (for example, updated from L08 to L09). Thus, each time the rotation command pulse CWP is input, the value of the number-of-times division step counter is updated, and when the value of the number-of-times division step counter is switched from L09 to L00, the value of the basic step counter is changed. It is updated (for example, updated from H00 to H01).

  The combination excitation switching command shown in FIG. 20 is generated at a timing unrelated to the rotation command pulse. This combination excitation switching command is generated for each combination excitation cycle TC by the combination excitation cycle output means 12c.

  In the excitation switching method based on the excitation cycle synchronization update shown in FIG. 20, only the first excitation set and the second excitation set stored in the excitation frequency ratio storage means 12i and the excitation frequency ratio (step) (step) Corresponding to the position). On the other hand, in the excitation switching method of basic step synchronization update 1, in addition to the combination excitation switching command, the first excitation group and the second excitation stored in the excitation frequency ratio storage means 12i with the update of the basic step counter. The set and the excitation frequency ratio are updated.

  As shown in FIG. 20, in the excitation switching method based on the excitation cycle synchronization update, the step position stored in the excitation frequency ratio storage means 12i is updated every combination excitation cycle TC generated every predetermined combination excitation cycle TC. Therefore, 5 to 6 microstep positions are thinned out.

  For example, when only the excitation switching method of excitation cycle synchronization update is used, when switching from microstep drive to full step drive, the excitation update cycle at step position 0100 is 2 × TC, and the excitation update cycle at step position 0200 is TC. Thus, the constant speed rotation is slightly deteriorated, and vibration is generated in the motor rotor.

  On the other hand, when microstep driving is performed using the excitation switching method of basic step synchronization update 1, the excitation update frequency increases in the vicinity of the basic step counter being updated, and the frequency division step is complemented. This makes the drive somewhat more stable. Further, since the basic step update cycle and the combination excitation cycle TC do not interfere with each other, no audible sound is generated. Therefore, even if the step position is updated in synchronization with the update of the basic step counter, there is no adverse effect.

  Further, in the rotation command pulse interval shown in FIG. 20, when switching from microstep driving to full step driving, the excitation update cycle at step position 0100, the excitation update cycle at step position 0200, and the excitation update cycle at step 0300. Therefore, by using the excitation switching method of the basic step synchronization update 1, the constant speed rotation at the time of full step driving is maintained.

  In the embodiment shown in FIG. 20, the step division stored as the step position stored in the excitation number ratio storage means 12i includes the number division step, and the microstep drive with thinning is performed. According to the experimental results, switching from microstep drive excitation to full step drive excitation at 5 rps (300 rpm) at the time of acceleration, and from full step drive excitation to microstep drive at 4.6 rps (276 rpm) at the time of deceleration. Even if it was configured to switch to excitation, vibration that would be a practical problem did not occur. Therefore, it is possible to already switch to full-step driving at a rotational speed much lower than that shown in FIG.

  Next, the excitation switching timing using the basic step synchronization update 1 when the update interval of the basic step counter becomes shorter than the interval of the combination excitation cycle TC will be described using FIG. For example, when the 5-phase stepping motor 1 with a mechanical angle of 7.2 ° is used and the basic step number = 10, the number of divisions m = 10, and the combination excitation cycle TC = 50 μs, the state shown in FIG. The rotor is rotating at about 60 rps (3600 rpm). Note that the description of the same items as those described in FIG. 20 is omitted.

  In the embodiment shown in FIG. 21, since the update interval of the basic step counter is shorter than the interval of the combination excitation cycle TC, many microstep positions including the basic angle step are thinned out. In the rotation command pulse interval shown in FIG. 21, it is no longer meaningful to perform microstep driving, so it is preferable to switch to full step driving.

  When full step driving is performed using the excitation switching method based on the excitation cycle synchronization update, the step positions in each excitation update cycle TC are 0100, 0200, 0400, 0600. The constant speed rotation of the rotor is slightly deteriorated, and vibration is generated in the motor rotor.

  On the other hand, when microstep driving by the excitation switching method of basic step synchronization update 1 is used, the excitation update frequency increases in the vicinity where the basic step counter is updated, and the number of times division step is complemented. As a result, the driving becomes somewhat stable, and even if the step position is updated in synchronization with the update of the basic step counter, no adverse effect is caused.

  In addition, when full step driving is performed using the excitation switching method of basic step synchronization update 1, the step position in each excitation update period TR is the step number of the basic step, and therefore constant speed rotation during full step driving. And calmness will be ensured.

  Therefore, by using the excitation switching method based on the basic step synchronization update 1 in addition to the excitation switching method based on the excitation cycle synchronization update, it is possible to reduce vibrations when the rotational speed of the motor rotor is high. Furthermore, by using the four-phase excitation that combines the two-phase excitation in the speed range where microstep drive is performed, by providing a state where all the coil terminals of the stepping motor are connected to either the positive electrode or the negative electrode, While stopping accuracy can be improved, smoothness of rotation can be ensured from the ultra low rotation range to the low rotation range. Further, as the number of rotations of the motor rotor increases, the number of steps for each combination excitation cycle TC can be increased naturally. In this way, the number of rotations to switch from microstep driving to full step driving can be selected from a wide rotation range without increasing the vibration of the motor rotor.

  In the case of performing full-step drive, the combination of excitations related to the number-of-times division step is not required, so that full-steps by two-phase excitation that enables quiet operation with low vibration until the excitation update period TR reaches 2 × T. Drive can be performed. Further, when switching to full-step driving by four-phase excitation, normal high-speed rotation can be performed even when the excitation update cycle TR is further shortened.

  Next, a method for switching excitation in the middle of the combination excitation cycle TC when realizing the excitation switching method based on the basic step synchronization update 1 will be described with reference to FIGS.

  FIG. 22 and FIG. 23 are diagrams showing the relationship between the excitation frequency ratio for each frequency division step, the unit excitation cycle T, and the combination excitation cycle TC in order to realize microstep driving. Among these, FIG. 22 is a diagram showing a state in which excitation according to a predetermined excitation frequency ratio is completed in the combination excitation cycle TC. The excitation ratio shown in FIG. 22 represents the excitation ratio determined by the excitation frequency ratio determining means 12d shown in FIG. 6 according to the number of steps in each frequency division step.

  On the other hand, FIG. 23 shows the excitation combination of the electrical angle position (step 1 * N) corresponding to H01 from the middle of the combination excitation cycle TC because the value of the basic step counter is switched from H00 to H01 within the combination excitation cycle TC. It is a figure showing the state currently switched to.

  As shown in FIG. 23, at time tc1, the value of the basic step counter is H00, and the value of the number-of-times division step counter is L08. Therefore, the electrical angle position at time tc1 = step 0 * N + (N / 10 ) The excitation ratio corresponding to * 8 is acquired by the excitation frequency ratio storage means 12i from the excitation frequency ratio determination means 12d and stored. Then, excitation output is performed at this excitation ratio.

  After the time tc1, when the rotation command pulse CWP is input and the value of the number division step counter transits from L08 to L09, and further when the rotation command pulse CWP is input at time tc2, the value of the number division step counter becomes L09. From L00 to L00, and the value of the basic step counter changes from H00 to H01. Then, the excitation frequency ratio storage means 12i newly acquires and stores the excitation ratio corresponding to the electrical angle position (step 1 * N) at time tc2 from the excitation frequency ratio determination means 12d. Then, as shown in FIG. 23, the newly stored excitation is output from time tc2 to time tc3.

  By doing so, in addition to the excitation switching method based on the excitation cycle synchronization update, the excitation switching method based on the basic step synchronization update 1 can be realized.

[Embodiment using basic step synchronous update 2]
Next, another embodiment of the excitation switching timing when the motor rotor of the five-phase stepping motor 1 is rotating will be described. In the embodiment using the basic step synchronization update 1 described above, in addition to the excitation switching method based on the excitation cycle synchronization update, an excitation switching method for updating excitation from the middle of the combined excitation cycle TC as the basic step counter is updated is used. It was. On the other hand, in the embodiment shown below, each time the value of the basic step counter is updated, the combination excitation cycle output means 12c outputs a combination excitation switching command and starts counting the combination excitation cycle TC anew. It is comprised so that it may do. Therefore, the excitation frequency ratio storage unit 12i can update excitation in synchronization with the basic step by switching excitation based on the combination excitation switching command output by the combination excitation cycle output unit 12c. This excitation switching method using the excitation switching timing will be referred to as basic step synchronization update 2.

  In addition to the excitation switching method using the basic step synchronization update 2, every time the value of the basic step counter is updated, the unit excitation cycle output means 12h outputs a unit excitation switching command and newly unit excitation. It can also be configured to start counting the period T.

  Excitation switching timing when the basic step synchronization update 2 is used together will be described with reference to FIGS. 24 and 25. FIG. The embodiment shown in FIGS. 24 and 25 shows a case where the number of basic steps = 10 and the number of times of division m = 10, as in the embodiment shown in FIG. Note that the same items as those shown in FIGS. 20 and 21 are given the same names, and descriptions thereof are omitted.

  24 and 25, the change in the value of the number division step counter (represented by a two-digit numerical value) when the rotation command pulse CWP is input, and the upper digit of the number division step counter. Of the basic step counter value (represented by a two-digit numerical value) corresponding to the above, a combination excitation switching command output at each combination excitation cycle TC, and a step stored in the excitation frequency ratio storage means 12i. The position (represented by a four-digit numerical value) is represented with the horizontal axis representing time. The excitation number ratio storage means 12i stores the first excitation group and the second excitation group and the excitation number ratio, but here, for convenience of explanation, the value of the number division step counter and the basic step counter And the value of.

  Of these figures, FIG. 24 shows a change in the step position when the rotation command pulse interval is about 1 / 7.5 of the combined excitation cycle TC. FIG. 25 shows a change in the step position when the update interval of the basic step counter is shorter than the combination excitation cycle TC.

  First, the excitation switching timing using the basic step synchronization update 2 when the rotation command pulse interval is about 1 / 7.5 of the combined excitation cycle TC will be described with reference to FIG. For example, when the 5-phase stepping motor 1 with a mechanical angle of 7.2 ° is used and the basic step number = 10, the number of divisions m = 10, and the combination excitation cycle TC = 50 μs, the state shown in FIG. The rotor is rotating at about 30 rps (1800 rpm). Note that the description of the same items as those described in FIG. 13 is omitted.

  As shown in FIG. 24, when the rotation command pulse CWP is input, the value of the frequency division step counter is updated at the rising edge (for example, updated from L08 to L09). Thus, each time the rotation command pulse CWP is input, the value of the number-of-times division step counter is updated, and the value of the basic step counter is updated when the value of the number-of-times division step counter is switched from L09 to L00. (For example, it is updated from H00 to H01).

  In the excitation switching method based on the excitation cycle synchronization update, the combination excitation switching command is generated for each combination excitation cycle TC by the combination excitation cycle output means 12c irrespective of the rotation command pulse. The combination excitation switching command by is output every time the value of the basic step counter is updated in addition to the conditions generated at each combination excitation cycle TC. Further, every time the value of the basic step counter is updated, counting of the combination excitation cycle TC is newly started.

  Therefore, in the excitation switching method of basic step synchronization update 2, in addition to the combination excitation switching command output every combination excitation cycle TC, the combination excitation switching command is output in synchronization with the update of the basic step counter, and the number of excitations The first excitation group and the second excitation group and the excitation frequency ratio stored in the ratio storage means 12i are updated.

  For example, in the embodiment shown in FIG. 24, since the rotation command pulse interval is considerably shorter than the combined excitation cycle TC, 5 to 6 microstep positions are thinned out. When only the excitation switching method of excitation cycle synchronization update is used, when switching from microstep drive to full step drive, the excitation update cycle at step position 0100 is 2 × TC, and the excitation update cycle at step position 0200 is As a result, the constant speed rotation is slightly deteriorated, and vibration is generated in the motor rotor.

  On the other hand, when microstep driving is performed using the excitation switching method of basic step synchronization update 2, the excitation update frequency is increased in the vicinity of the basic step counter being updated, and the frequency division step is complemented. This makes the drive somewhat more stable. Therefore, even if the step position is updated in synchronization with the update of the basic step counter, there is no adverse effect.

  Further, in the rotation command pulse interval shown in FIG. 24, when switching from micro-step driving to full-step driving, excitation update cycle at step position 0100, excitation update cycle at step position 0200, excitation update cycle at step 0300 Therefore, by using the excitation switching method of the basic step synchronization update 2, constant speed rotation at the time of full step driving is maintained.

  In the embodiment shown in FIG. 24, the step number stored in the excitation frequency ratio storage means 12i includes a frequency division step, and shows a state where microstep driving with thinning is performed. According to the experimental results, switching from microstep drive excitation to full step drive excitation at 5 rps (300 rpm) at the time of acceleration, and from full step drive excitation to microstep drive at 4.6 rps (276 rpm) at the time of deceleration. Even if it was configured to switch to excitation, vibration that would be a practical problem did not occur. Therefore, it is possible to already switch to full-step driving at a rotational speed much lower than that shown in FIG.

  Next, the excitation switching timing using the basic step synchronization update 2 when the update interval of the basic step counter becomes shorter than the interval of the combination excitation cycle TC will be described using FIG. For example, when a 5-phase stepping motor 1 with a mechanical angle of 7.2 ° is used and the basic step number = 10, the number of divisions m = 10, and the combination excitation cycle TC = 50 μs, the state shown in FIG. The rotor is rotating at about 60 rps (3600 rpm). Note that the description of the same items as those described in FIG. 13 is omitted.

  In the embodiment shown in FIG. 25, since the update interval of the basic step counter is shorter than the interval of the combination excitation cycle TC, many microstep positions including the basic angle step are thinned out. In the rotation command pulse interval shown in FIG. 25, it is no longer meaningful to perform microstep driving, so it is preferable to switch to full step driving.

  When full step drive is performed using the excitation switching method based on the excitation cycle synchronization update, the step positions in each excitation update cycle TC are 0100, 0200, 0400, 0600. The constant speed rotation of the rotor is slightly deteriorated, and vibration is generated in the motor rotor.

  On the other hand, when full-step driving by the excitation switching method of basic step synchronization update 2 is used, excitation is switched every time the basic step counter is updated, so the step position in each excitation update period TR is As the number of steps increases, constant speed rotation during full-step driving is ensured.

  Therefore, every time the value of the basic step counter is updated, a combination excitation switching command is output, and the excitation switching method of basic step synchronous update 2 that newly starts counting the combination excitation cycle TC is used. It is possible to reduce vibration when the rotational speed of the motor rotor is high. Furthermore, by using the four-phase excitation that combines the two-phase excitation in the speed range where microstep drive is performed, by providing a state where all the coil terminals of the stepping motor are connected to either the positive electrode or the negative electrode, While stopping accuracy can be improved, smoothness of rotation can be ensured from the ultra low rotation range to the low rotation range. Further, the number of steps can be increased naturally as the number of rotations of the motor rotor increases. In this manner, the rotation speed for switching from microstep driving to full step driving can be selected from a wider rotation range without increasing the vibration of the motor rotor.

  In the case of performing full-step drive, the combination of excitations related to the number-of-times division step is not required, so that full-steps by two-phase excitation that enables quiet operation with low vibration until the excitation update period TR reaches 2 × T. Drive can be performed. Further, when switching to full-step driving by four-phase excitation, normal high-speed rotation can be performed even when the excitation update cycle TR is further shortened.

  Next, features of the stepping motor driving apparatus according to the present invention will be described with reference to FIG. FIG. 26A is a diagram schematically showing the range of the rotational speed at which the vibration reduction effect is obtained when Patent Document 1 or 3 is used. FIG. 26 (b) is a diagram schematically showing a rotation speed range in which a vibration reduction effect can be obtained when the stepping motor driving device according to the present invention is used.

  As shown in FIG. 26 (a), the vibration reduction effect when using Patent Document 1 or 3 cited as the background art is to reduce only the vibration generated at the boundary between microstep driving and full step driving. It is intended. Therefore, smooth rotation of the motor rotor to the highest possible number of revolutions, reduction of short-circuit current of the drive element, improvement of micro-step resolution, and support for more types of winding specifications for stepping motors It is difficult to provide a stepping motor drive device.

  On the other hand, in the stepping motor drive device according to the present invention, in the microstep drive region without dead time, the stop accuracy is improved and the motor rotation is achieved by the combination of two-phase excitation in which the excitation coil terminal is not in a high impedance state. It enables smooth driving with stable rotation of the child.

  In addition, in the microstep drive region including dead time, a short-circuit current that causes the high-side drive element and the low-side drive element to be in a conductive state at the same time due to the voltage value of the drive power source that increases as the rotation speed of the motor rotor increases. In order to reduce the dead time, a dead time is inserted into the high side command or the low side command. Thereby, it is possible to reduce the short-circuit current while stabilizing the rotation of the motor rotor by continuing the excitation by the combination of the two-phase excitation as much as possible.

  For example, this two-phase excitation can be continued until just before the voltage saturation of the constant current control executed by the motor current control means 16. In particular, for a stepping motor having an excitation coil having a low inductance, two-phase excitation having excellent rotational stability up to a higher rotation can be used.

  In addition, by performing full-phase drive with two-phase excitation including dead time, full-step drive with two-phase excitation is performed until the basic step update cycle reaches 2 × T (T = unit excitation cycle). The motor rotor can be smoothly rotated. In a region where the constant current control of the exciting coil is not effective due to saturation of the voltage value of the driving power supply, switching for microstep driving can be masked by inserting a dead time DT. As a result, it is possible to reduce the ripple of the voltage value of the drive power supply caused by switching in the region where the constant current control is not effective, and to reduce the vibration of the motor rotor.

  In addition, when the rotational speed of the motor rotor further increases, it is possible to switch to full-step driving by four-phase excitation in which the dead time DT is expanded to the unit excitation period T, and to cope with higher rotation. When the constant current control voltage controlled by the motor current control means 16 reaches the saturation voltage value, it is possible to switch to the full step drive by the four-phase excitation.

  The stepping motor driving apparatus and the microstep method according to the present invention are suitable for applications that require quietness in addition to precise positioning or low-vibration driving in a low rotation range. For example, the present invention can be applied to an optical measurement device, an optoelectronic device manufacturing device, an organic EL manufacturing device, a device process device, an organic semiconductor element manufacturing device, or the like.

  In addition, as an application of the optical measurement device, a parallel optical calculation technology, a laser stabilization technology, an ultra-high rotation region spectroscopy technology, an ultra-high rotation region light control technology, or an optical control technology field such as an optical pulse timing synchronization technology, There may be mentioned technical fields such as single-photon detection technology, ultra-high rotational speed optical measurement technology, hologram measurement technology, various surface spectroscopy technologies, electroluminescence measurement technology, mobility measurement technology, or interference measurement technology.

  In the above embodiments, the microstep method of the present invention is used to drive a rotary stepping motor. However, the microstep method can be applied to a direct-acting stepping motor.

It is a block diagram which shows the internal structure of a stepping motor drive device which can insert a high impedance state for a while when exciting each excitation coil of a 5-phase stepping motor. (A) is a figure which defines the excitation coil 1a-1e of the 5-phase stepping motor which employ | adopted the pentagon connection system, and the direction of the excitation current of excitation phase ABCDEabcde. (B) is a diagram defining the relationship between the excitation phase ABCDEabcde of the five-phase stepping motor and the torque vectors VA to Ve. It is a figure which shows the example of a combination of the excitation phase which positions a motor rotor in a predetermined | prescribed basic step position. It is a figure which shows the other Example of the combination of the excitation phase which positions a motor rotor in a predetermined | prescribed basic step position. It is a figure explaining each function in the excitation waveform determination means shown in FIG. It is a figure which shows the other excitation form which collectively outputs the excitation group of each excitation phase in an excitation frequency ratio determination means. It is a figure which shows the structural example of the high side command data and low side command data which a drive element command generation means produces | generates. It is a figure showing the timing of the high side command and low side command which a dead time insertion means outputs. It is a figure showing the timing of the high side command and low side command in which the dead time DT was inserted by the dead time insertion means. It is a figure showing the timing of the high side command and low side command which inserted the dead time DT = T / 2 using the combination 1 of 2 phase excitation. It is a chart showing the excitation group at the time of performing step of each basic step of Step 0 * N to Step 9 * N using the combination 1 of two-phase excitation. It is a figure showing the timing of the high side command and low side command which inserted the dead time DT using the combination 2 of 2 phase excitation. It is a figure showing the timing of the high side command and low side command which inserted the dead time DT = T / 2 using the combination 2 of 2 phase excitation. It is a chart showing the excitation group at the time of performing the step of each basic step of Step 0 * N to Step 9 * N using the combination 2 of two-phase excitation. It is a figure which shows the case where several dead time DT is set according to the voltage value of a drive power supply. It is a figure which shows the case where the dead time DT is increased continuously according to the voltage value of a drive power supply. It is a figure showing the relationship between the rotation speed of the motor rotor in multiple types of stepping motors, and the voltage value of a drive power supply. It is a chart showing embodiment which sets dead time DT according to the number of rotations of a motor rotor. It is a graph showing embodiment which sets a dead time rate according to the voltage value of a drive power supply. It is a figure explaining the excitation switching timing using the basic step synchronous update 1 in case a rotation command pulse interval is about 1 / 7.5 of the combination excitation cycle TC. It is a figure explaining the excitation switching timing using the basic step synchronous update 1 when the update interval of a basic step counter becomes shorter than the space | interval of the combination excitation period TC. FIG. 7 is a diagram showing a transition of the excitation frequency ratio according to the number of steps in the frequency division step determined by the excitation frequency ratio determining means shown in FIG. 6, and in the combination excitation cycle TC, the excitation according to a predetermined excitation frequency ratio It is a figure showing the state which is completed. It is a figure showing the state which switched the excitation combination within the combination excitation period TC in connection with the value of a basic step counter being updated. It is a figure explaining the excitation switching timing using the basic step synchronous update 2 in case a rotation command pulse interval is about 1 / 7.5 of the combination excitation cycle TC. It is a figure explaining the excitation switching timing using the basic step synchronous update 2 when the update interval of a basic step counter becomes shorter than the interval of the combination excitation cycle TC. (A) is the figure which represented typically the range of the rotation speed from which the vibration reduction effect is acquired when patent document 1 or 3 is used, (b) uses the stepping motor drive device which concerns on this invention. It is the figure which represented typically the range of the rotation speed from which a vibration reduction effect is acquired when there exists. It is a figure explaining the drive circuit for implement | achieving the drive system of the stepping motor described in patent document 1. FIG. It is a figure explaining the drive pattern at the time of the full step drive shown by FIG. 3 of patent document 1. FIG. It is a figure explaining the drive pattern at the time of the micro step drive shown by FIG. 2 of patent document 1. FIG. FIG. 9 is a diagram illustrating a voltage (duty) applied to a terminal A during microstep driving shown in FIG. 8 of Patent Document 1. It is a figure explaining the PWM pattern at the time of the micro step drive shown by FIG. 6 of patent document 1. FIG. FIG. 6 is a diagram for explaining a transition of a PWM pattern when shifting from microstep driving shown in FIG. 5 of Patent Document 1 to full step driving. FIG. 8 is a diagram for explaining the transition of a PWM pattern using M1 and M2 when shifting from microstep driving shown in FIG. 7 of Patent Document 1 to full step driving. It is the figure showing the relationship between a rotation command pulse and a PWM waveform in the case of updating an electrical angle in synchronization with a rotation command pulse during conventional microstep drive. The transient state of the gate voltage change of the drive element when the high side drive element is turned on and the low side drive element is turned off simultaneously is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 5-phase stepping motor 1a-1e Excitation coil 10 Stepping motor drive device 12 Excitation waveform determination means 12a Electrical angle position management means 12b Excitation phase combination output means 12c Combination excitation cycle output means 12d Excitation frequency ratio determination means (Excitation ratio determination means)
12h Single excitation cycle output means 12i Excitation number ratio storage means (excitation ratio storage means)
12j Driving element commanding means 12k Dead time inserting means 12l Dead time generating means 12m First threshold judging means 12n Second threshold judging means 12v Command rotational speed detecting means 14 Constant current control circuit 15 Current detecting resistor 16 Motor current controlling means C1 , C2 Capacitors D1 to D11 Diode L1 Choke coil PS Power supply TR1 to TR10 Drive element TR11 Transistors VA to VE, Va to Ve Torque vector

Claims (8)

In a stepping motor driving apparatus that realizes a microstep for dividing a basic step angle α of an N-phase stepping motor into m steps,
When a rotation command pulse of the N-phase stepping motor is input, the m-divided counter that counts and outputs the number of steps in the fine step, and the step number in the basic step that is located in the upper digit of the m-divided counter are counted. An electrical angle position management means having a basic step counter for outputting
The motor rotor of the N-phase stepping motor, said to position the basic step position of 1 corresponding to step radix basic steps, one for exciting the two-phase combination of excitation coils sac Chi plants constant of N phase An excitation phase combination output means for outputting an excitation combination of the excitation set and another excitation set for exciting another two-phase combination for positioning at another basic step position;
Excitation that determines the excitation ratio of the two excitation combinations by gradually increasing and decreasing the number of excitations or excitation times of the two excitation combinations according to the value of the m-dividing counter and the value of the basic step counter, respectively. A ratio determining means;
Unit excitation period output means for outputting a unit excitation switching command for switching excitation for the unit excitation phases constituting the excitation group each time a predetermined unit excitation period T is counted;
Each time a combination excitation cycle TC composed of an integral multiple of the unit excitation cycle T is counted, a combination excitation switching command for switching excitation according to the two excitation combinations according to the excitation ratio is output. Periodic output means;
Excitation ratio storage means for storing a new excitation ratio each time the combination excitation switching command is output;
A high-side drive element that is provided for each of the N-phase excitation coil terminals and controls conduction or interruption between the excitation coil and the positive electrode of the drive power supply, and controls conduction or interruption between the excitation coil and the negative electrode of the drive power supply. A low-side drive element to
In order to switch the excitation for the unit excitation phases constituting the two excitation combinations every time the unit excitation switching command is output, using the excitation ratio stored in the excitation ratio storage means, Driving element command generating means for generating high-side command data for driving and low-side command data for driving the low-side driving element;
Dead time generating means for generating a dead time determined in accordance with a voltage value applied to the exciting coil or the rotation speed of the motor rotor;
Each time the unit excitation switching command is output, a high side command and a low side command corresponding to the high side command data and low side command data are output, and when the unit excitation switching command is output, the high side command is output. When the command and the low-side command are switched simultaneously, a new high-side command or low-side command in which the dead time is inserted is generated for either the high-side command or the low-side command at the time of the switching. Dead time insertion means for inserting a high impedance state in which both the high side driving element and the low side driving element are cut off;
With
The high side driving element and the low side driving element are formed by exciting the N-phase excitation coil based on the high side command and the low side command ,
Three-phase excitation is performed on the N-phase excitation coil using the new high-side command or the low-side command with the dead time inserted based on the two excitation combinations before and after the dead time insertion. A stepping motor driving apparatus characterized by the above excitation. Current detecting means for detecting a current flowing in the exciting coil;
Current control means for controlling a voltage value of the drive power supply applied to the exciting coil so that the detected current is determined within a predetermined range;
With
2. The stepping motor driving apparatus according to claim 1, wherein the dead time generation unit sets the dead time to be long when the voltage value after the constant current control is high. Current detecting means for detecting a current flowing in the exciting coil;
Current control means for controlling a voltage value of the drive power supply applied to the exciting coil so that the detected current is determined within a predetermined range;
With
The dead time generating means adds a first dead time when the voltage value after the constant current control exceeds a first threshold value,
The first dead time is subtracted when the voltage value after the constant current control exceeds the first threshold and then falls below a second threshold lower than the first threshold. The stepping motor driving apparatus according to claim 1. Current detecting means for detecting a current flowing in the exciting coil;
Current control means for controlling a voltage value of the drive power supply applied to the exciting coil so that the detected current is determined within a predetermined range;
With
The dead time generation means gradually increases the first dead time at a first increase rate when the voltage value after the constant current control exceeds a first threshold value,
When the voltage value after the constant current control exceeds the first threshold value and then falls below a second threshold value that is lower than the first threshold value, the first dead time is set to a first decrease rate. The stepping motor driving apparatus according to claim 1, wherein the stepping motor is gradually reduced at a step. Current detecting means for detecting a current flowing in the exciting coil;
Current control means for controlling a voltage value of the drive power supply applied to the exciting coil so that the detected current is determined within a predetermined range;
With
When determining that the voltage value has exceeded the first threshold value, the dead time generation means gradually increases the dead time at a predetermined increase rate until a time corresponding to the unit excitation period T,
When it is determined that the voltage value has fallen below the second threshold value after the voltage value has exceeded the first threshold value, the dead time is gradually reduced from the time corresponding to the unit excitation period T at a predetermined decrease rate. The stepping motor driving apparatus according to claim 1, wherein:   6. The excitation ratio storage means stores the new excitation ratio each time the combination excitation switching command is output or the value of the basic step counter is updated. A stepping motor driving apparatus according to 1.   The combination excitation cycle output means is configured to switch the excitation according to the two excitation combinations according to the excitation ratio every time the combination excitation cycle TC composed of an integral multiple of the unit excitation cycle T is counted. 2. A switching command is output, and each time the value of the basic step counter is updated, the combination excitation switching command is output and counting of the combination excitation cycle TC is newly started. 5. A stepping motor driving device according to 5.   A driving method of an N-phase stepping motor using the stepping motor driving device according to any one of claims 1 to 7.

Images