JP2010284016A - Two-phase stepping motor drive device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To readily drive a two-phase stepping motor at a step angle unit smaller compared to a half step angle. <P>SOLUTION: The drive device 1, a device for driving a two-phase stepping motor M of common type with a common AB phase, includes a bipolar type switching section 10, and an excitation control section 20 for turning on and off each of switching elements Q1-Q8 in accordance with an input pulse α. The excitation control section 20 is configured to turn on and off the switching elements Q1-Q8, in a predetermined pattern per split step (0.45°) obtained by dividing a basic step into four. The control section is configured to control some of the switching elements Q1-Q8 for the current change phase coils per microstep in a period of split step, and to bring the other switching elements into an active state or an inactive state in the period of the split step. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a two-phase stepping motor driving apparatus capable of driving a two-phase stepping motor at low cost with high resolution and high accuracy.

  Stepping motors are widely used in various devices by taking advantage of the characteristics that positioning control and confirmation can be easily performed in an open loop without using a position sensor. When stepping motors are categorized by the number of phases, the two-phase stepping motors that are most frequently used at present are. The main reason is that the cost of the entire motor device including the driving device (driver) can be kept low.

  In the case of a two-phase stepping motor, representative examples of the excitation method include a one-phase excitation method, a two-phase excitation method, and a 1-2 phase excitation method. Full-step drive (basic step angle: 1.8 °) is realized by the 1-phase excitation method or 2-phase excitation method, and half-step drive (half-step angle: 0.9 °) is realized by the 1-2 phase excitation method. The In addition, the micro-step drive method, which can reduce the step angle, has developed a two-phase excitation method in principle because a current is always passed through a two-phase coil and the current level is changed finely. It is a thing.

  The circuit configuration of the two-phase stepping motor drive device differs greatly depending not only on the excitation method but also on the motor coil connection method. For example, as an example of a drive device used for an AB-phase common common type two-phase stepping motor, there is one disclosed in Patent Document 1 or the like.

JP-A-10-174416

  However, according to the above conventional example, it is difficult to drive the two-phase stepping motor in units of a step angle smaller than the half step angle unless the microstep driving method is adopted. Therefore, when high positioning accuracy is required, the current situation is that a 5-phase stepping motor or the like is used instead of the 2-phase stepping motor, resulting in a significant increase in cost. If the microstep drive method is used, it is possible to drive the motor with high resolution. However, in reality, the uniformity of angle division is not maintained, and it is difficult to achieve high accuracy. The problem is also pointed out.

  The present invention has been created under the above-described background, and the object of the present invention is to provide a two-phase stepping motor that can be easily driven by a step angle unit smaller than a half step angle. It is to provide a stepping motor driving device.

  In order to solve the above problems, the two-phase stepping motor driving device of the present invention includes a midpoint a between the positive terminal A and the negative terminal / A of the A phase coil and the positive terminal B of the B phase coil. A device for driving a two-phase stepping motor having a coil connection structure in which a midpoint b between the negative terminal / B and a common terminal is electrically connected to each other, using two sets of full bridge circuits of switching elements A bipolar switching unit that generates currents flowing in the A-phase and B-phase coils of the motor, and each switching element that constitutes the switching unit according to the input pulse is divided into four basic steps in a predetermined pattern. And an excitation control unit for turning on and off. Especially for the excitation controller, (1) The current flowing in the A phase coil is changed sequentially from the positive direction to the negative direction in the period of the basic step n, and the current flowing in the B phase coil is maintained at the H level in the positive direction. The current flowing through the A phase coil at the basic step n + 1 is maintained at the H level in the negative direction, the current flowing through the B phase coil is sequentially changed from the positive direction to the negative direction, and flows through the A phase coil during the basic step n + 2. The current is sequentially changed from the negative direction to the positive direction, the current flowing through the B phase coil is maintained at the H level in the negative direction, the current flowing through the A phase coil is maintained at the H level in the positive direction at basic step n + 3, and B The current flowing in the phase coil is changed sequentially from the negative direction to the positive direction. (2) In the process of changing the current flowing in the A phase coil from the positive direction to the negative direction, In the process of changing the current flowing through the A-phase coil from the negative direction to the positive direction, the current flows sequentially from the middle point a to the negative terminal / A and similarly from the middle point a to the positive terminal A. , The current flowing through the B-phase coil from the middle point a through the middle point b to the positive terminal A, and from the middle point a to the negative terminal / A sequentially, In the process of changing from the negative direction to the negative direction, a current flows sequentially from the middle point b to the negative terminal / B through the middle point a of the A-phase coil, and similarly from the middle point b to the positive terminal B. In the process of changing the current flowing through the phase coil from the negative direction to the positive direction, the middle point b is changed from the middle point a through the middle point a to the positive terminal B, and similarly from the middle point b to the negative terminal / B sequentially. The configuration is such that a current flows.

  According to the above-described invention, the two-phase stepping motor has a coil connection structure in which the middle point a of the A-phase coil and the middle point b of the B-phase coil are electrically connected to each other in common. It is possible to drive with a 1/4 step excitation pattern. Therefore, it is very significant in reducing the cost of the entire configuration including the motor and increasing the resolution of driving of the motor.

  When the two-phase stepping motor is driven by microsteps, the excitation control unit controls some switching elements among the switching elements related to the current change phase coil for each microstep during the division step, and other switching elements. May be configured to be in an active state or an inactive state during the division step. The current maintenance phase coil referred to here is a coil on the side of the A phase and B phase coils that maintains the current at the H level or the L level during the basic step.

  According to the above-described invention of the subordinate concept, the number of steps of the excitation sequence pattern, which is a premise of microstep drive, is doubled compared to the prior art, so that it is possible to further increase the resolution of the motor. Moreover, since the switching elements related to the fine current control required for microstep drive are only a part rather than all phases, the structure related to the fine current control is simplified, and this also makes it possible to reduce the cost. Become.

  As a specific example of the excitation control unit in this case, the duty ratio data of the PWM waveform necessary for pulse width modulation (PWM) control of the output current of some switching elements related to the current changing phase coil is the microstep angle. A memory unit pre-recorded every time, an address generation unit that sequentially reads data on the memory unit according to an input pulse, a PWM signal generation unit that generates a PWM signal based on the data on the memory unit, and the input pulse The phase excitation counter unit that calculates the number of steps of the excitation sequence by counting the PWM signal output from the PWM signal generation unit with the phase distribution pattern corresponding to the number of steps indicated by the phase excitation counter unit, the H level signal, L Level signals are phase-distributed and the switching elements constituting the switching unit are turned on by the phase-distributed signals. There is a structure having a phase distribution circuit section for off.

  In the above-described constant current control system, the excitation control unit is preferably configured so that the current values of the H level and the L level can be finely adjusted when the other switching elements are in the active state and the inactive state. .

  According to the subordinate concept invention described above, the current values of the H level and the L level when the other switching elements are in the active state and the inactive state, that is, the current related to the current maintenance phase are finely adjusted in the positive or negative direction. As a result, the current related to the current changing phase also changes in the opposite direction. Therefore, even if there are variations in the characteristics of the output stage of the two-phase stepping motor or the driving device, the lead angle of the motor can be adjusted by appropriately balancing the current related to the current maintaining phase and the current related to the current changing phase. As a result, it becomes possible to increase the precision of microstep drive.

  In the above apparatus, the duty ratio data of the PWM waveform is divided into basic step angles or divisions so that the stepping motor can be microstep driven in units of angles obtained by equally finely dividing the basic step angle. It is preferable that the entire range of the step angle is finely adjusted for each micro step angle.

  According to the invention of the subordinate concept described above, since the data of the duty ratio of the PWM waveform recorded in the memory unit is finely adjusted for each microstep angle for the entire range of the basic step angle or the divided step angle, the two-phase stepping When the motor is micro-step driven, the uniformity of the angle division is maintained, and accordingly, it is possible to increase the accuracy of the micro-step drive.

1 is a configuration diagram of a two-phase stepping motor driving apparatus according to an embodiment of the present invention. It is a figure which shows the excitation sequence employ | adopted as the same apparatus. It is a figure for demonstrating the content of the data recorded on the memory part contained in the excitation control part of the apparatus. It is the figure which showed typically the change of the electric current which flows into each phase coil of a two-phase stepping motor with progress of every 1/4 step of the excitation sequence pattern shown in FIG. It is a timing chart which shows the change of the electric current which flows into each phase coil of the 2 phase stepping motor. It is a figure which concerns on a 1st modification, Comprising: It is a figure which shows another excitation sequence employ | adopted as the same apparatus. It is a figure which shows the waveform of the various excitation signals which turn on / off each switching element of the apparatus. It is the figure which showed the change of the electric current which flows into each phase coil of a two-phase stepping motor with progress of every 1/4 step of the excitation sequence pattern shown in FIG. It is a figure which concerns on a 2nd modification, Comprising: It is a figure which shows another excitation sequence of the apparatus. It is a figure which shows the waveform of the various excitation signals which turn on / off each switching element of the apparatus. It is a figure which concerns on a 3rd modification, Comprising: It is a figure which shows another excitation sequence pattern employ | adopted as the same apparatus. It is the figure which showed typically the change of the electric current which flows into each phase coil of a two-phase stepping motor with progress of every 1/4 step of the excitation sequence pattern shown in FIG.

  Hereinafter, a two-phase stepping motor driving apparatus (hereinafter simply referred to as a driving apparatus) according to an embodiment of the present invention will be described with reference to FIGS. It should be noted that those for which the correspondence between the invention-specifying matters described in the claims and the components of the apparatus is unknown are shown together in the description of reference numerals described later.

  For the driving apparatus 1 exemplified here, as shown in FIG. 1, a two-phase stepping motor M (hereinafter simply referred to as a stepping motor M) is controlled by a constant current pulse width modulation (PWM) control system in accordance with an input pulse α. This is a device for microstep driving. In the figure, 10 is a switching unit, 20 is an excitation control unit, 30 is a power supply circuit unit, and 40 is a constant current circuit unit. The drive device 1 is configured by these units.

  The stepping motor M is a stepping motor having an HB type motor structure with two phases, and is externally attached to the driving device 1 using four lead wires. The coil connection structure is an AB phase common common type, a midpoint a between the positive terminal A and the negative terminal / A of the A phase coil, the positive terminal B and the negative terminal / B of the B phase coil, The middle point b is electrically connected in common.

  The power supply circuit 30 is a circuit in which a power transformer, a rectifying diode bridge, and the like are combined. The input commercial alternating current is converted into a predetermined level of direct current voltage and supplied to each circuit component.

  The constant current circuit unit 40 is a known constant current circuit connected between the power supply circuit unit 30 and the switching unit 10, and the power source current supplied to the switching unit 10 is negatively feedback controlled using a transistor or the like. The current is constant.

  The switching unit 10 is a bipolar drive circuit using switching elements Q1 to Q8 which are NPN type transistors, and is a full bridge circuit 11 of switching elements Q1 to Q4 and a full bridge circuit of switching elements Q1 to Q4. 12 are used to generate each current flowing in the A-phase and B-phase coils of the stepping motor M.

  The excitation signals input to the bases of the switching elements Q1, Q2, Q3, Q4, Q5, Q6, Q7, and Q8 are represented by A +, A−, / A +, / A−, B +, B−, / Expressed as B +, / B-.

  The excitation control unit 20 generates excitation signals A +, A-, / A +, / A-, B +, B-, / B +, / B- to turn on and off the switching elements Q1 to Q8 according to the input pulse α. The switching elements Q1 to Q8 can be turned on / off in a predetermined pattern every divided step (divided step angle: 0.45 °) obtained by dividing the basic step (basic step angle: 1.8 °) into four. It has become a structure. In addition, some switching elements among the switching elements Q1 to Q8 related to the current changing phase coil to be described later are controlled for each microstep during the division step, and the other switching elements are in the active state during the division step. Alternatively, it is configured to be in an inactive state.

  The excitation sequence for turning on / off the switching elements Q1 to Q8 is as shown in FIG. 2, and the current actually flowing through the A phase coil and the B phase coil of the stepping motor M by this excitation sequence is as shown in FIG. 2 and FIG. 5, “0” to “3” shown in the upper part indicate the number of basic steps, and “0-0” to “3-3” shown in the lower part thereof. Indicates the number of division steps. “H” in FIG. 2 indicates that an H level signal is distributed to each excitation signal for each division step. For “L” in FIG. 2, an L level signal is provided for each division step. This shows that the excitation signal is distributed. The same applies to FIG. 6, FIG. 9 and FIG. “PWM (I)” to “PWM (IV)” in FIG. 2 indicates that four types of patterns of PWM signals are distributed to each excitation signal.

  That is, as shown in FIGS. 2 and 5, the current flowing through the A-phase coil is changed sequentially from the positive direction to the negative direction during the basic step 0 period, and the current flowing through the B-phase coil is maintained at the H level in the positive direction. The current flowing in the A phase coil in the basic step 1 is maintained at the H level in the negative direction, the current flowing in the B phase coil is sequentially changed from the positive direction to the negative direction, and the A phase coil is changed in the basic step 2 period. The current flowing is changed sequentially from the negative direction to the positive direction, the current flowing in the B phase coil is maintained at the H level in the negative direction, and the current flowing in the A phase coil in the basic step 3 is maintained at the H level in the positive direction. The current flowing through the B-phase coil is sequentially changed from the negative direction to the positive direction.

  As described above, in the basic steps 0 and 2, the magnitude and direction of the current flowing through the A-phase coil of the stepping motor M are changed, and the magnitude of the current flowing through the B-phase coil is maintained at the H level or the L level. On the other hand, in basic steps 1 and 3, the magnitude of the current flowing through the A-phase coil is maintained at the L level or the H level, and the magnitude and direction of the current flowing through the B-phase coil changes.

  Of the A-phase and B-phase coils of the stepping motor M, the coil on the side that maintains the current at the H level or the L level in each period of the basic steps 0 to 3 is defined as the current maintaining phase coil. The coil that changes the current in the period is a current changing phase coil.

  A specific configuration of the excitation control unit 20 having a function for realizing the above-described excitation sequence is as follows.

  In this embodiment, the excitation control unit 20 includes an address generation unit 21, a memory unit 22, a PWM signal generation unit 23, a phase distribution circuit unit 24, a phase excitation counter unit 25, and a resolution setting unit 26 as shown in FIG. It has become the composition.

  For the memory unit 22, the duty ratio data of the PWM waveform necessary for PWM control of the output current of some of the switching elements related to the current changing phase coil is every microstep angle in all angle regions corresponding to the basic step. Pre-recorded.

  FIG. 3 shows the contents of the data recorded in the memory 22 in the case of performing the microstep drive in which the stepping motor M is angle-divided by 100 with respect to the basic step angle (1.8 °). The horizontal axis of the graph in FIG. 3 indicates the microstep angle, and the vertical axis indicates the duty ratio of the PWM waveform.

  Each data group indicated by “I”, “II”, “III”, and “IV” in FIG. 3 includes “PWM (I)”, “PWM (II)”, and “PWM (III)” shown in FIG. And data necessary for creating a waveform of a PWM signal related to “PWM (IV)”. Conventional data is represented by a linear expression, but the data used in the present invention varies as shown in the partially enlarged view of FIG. Specifically, the duty ratio data of the PWM waveform on the memory unit 22 is experimental data obtained by actually driving the stepping motor M by microstep driving and measuring the advance angle, and the basic step angle is equalized. The total angular range (basic step angle) of the basic step is finely adjusted every microstep angle (0.018 ° in the illustrated example) so that the stepping motor M can be microstep driven in units of finely divided angles. Is.

  The resolution setting unit 26 is a switch or the like for setting and inputting the resolution of the microstep angle, and can be set in three stages in this embodiment. For example, if the maximum microstep angle is 0.018 ° as in the above example, 0.018 ° (resolution: 1/100), 0.036 ° (resolution 1/50), 0 through the resolution setting unit 26. .072 ° (resolution: 1/25) can be set.

  The address generation unit 21 is a circuit unit that sequentially reads data on the memory unit 22 in accordance with the input pulse α as shown in FIG. Specifically, the input pulse α is counted using a counter or the like, and an address signal for sequentially reading data on the memory unit 22 based on the count value and the setting value of the resolution setting unit 26 is generated. It has become.

  A specific operation will be described using the example shown in FIG. When the set value of the resolution setting value 26 is 0.018 °, when 24 input pulses α are input, the address is sequentially changed from 0 to 25 and counted up. All the data of “PWM (I)” is read out. Subsequently, when 25 input pulses α are input, the address is sequentially changed from 25 to 49, and all the data of “PWM (II)” on the memory unit 22 is read in this process. The data of “PWM (III)” and “PWM (IV)” on the memory unit 22 are read out in the same manner. This is repeated thereafter. When the direction signal is in the negative direction, it is read out in the opposite manner to the above.

  When the set value of the resolution setting value 26 is 0.036 °, when twelve input pulses α are input, the address is sequentially changed by skipping two addresses from 0 to 24, that is, compared with the above. Counting up at twice the speed, and in this process, a part of the data of “PWM (I)” on the memory unit 22 is read out. Subsequently, two addresses are skipped from 26 to 48, and the addresses are sequentially changed and counted up. In this process, a part of the data of “PWM (II)” on the memory unit 22 is read. The data “PWM (III)” and “PWM (IV)” on the memory unit 22 are read in exactly the same way. This is repeated thereafter. When the direction signal is in the negative direction, it is read out in the opposite manner to the above.

  When the set value of the resolution setting value 26 is 0.072 °, when six input pulses α are input, the address is changed sequentially from four to four from 0 to 24, that is, compared with the above. The data is counted up four times faster, and in this process, a part of the data of “PWM (I)” on the memory unit 22 is read. Subsequently, four addresses are skipped from 28 to 48 and sequentially changed and counted up. In this process, a part of the data of “PWM (II)” on the memory unit 22 is read. The data “PWM (III)” and “PWM (IV)” on the memory unit 22 are read in exactly the same way. This is repeated thereafter. When the direction signal is in the negative direction, it is read out in the opposite manner to the above.

  The phase excitation counter unit 25 is a counter that counts the input pulse α in accordance with the set value of the resolution setting value 26. The number of steps of the excitation sequence, that is, the number of basic steps 0 to 3 or the number of decomposition steps 0-0 to 3-3. Are counted.

  A specific operation will be described using the example shown in FIG. When the set value of the resolution setting value 26 is 0.018 °, it is counted each time 24 (or 25) input pulses α are input, and the counted value is divided into decomposition steps 0-0, 0-1, 0. -2, 0-3, 1-0 ... 3-3 are shown sequentially. This is repeated thereafter. When the set value of the resolution setting value 26 is 0.036, it is counted every time 12 input pulses α are input, and the counted value is divided into decomposition steps 0-0, 0-2, 1-0, 1-2. ... 3-3 are shown sequentially. This is repeated thereafter. When the set value of the resolution setting value 26 is 0.072, it is counted every time six input pulses α are input, and the counted value is the basic step 0, 1, 2, 3 or the decomposition step 0-0, 1 -0, 2-0, 3-0 are shown sequentially. This is repeated thereafter.

  The PWM signal generation unit 23 is a circuit unit that generates a PWM signal based on data on the memory unit 22 read by the address generation unit 21 as shown in FIG. Specifically, when the data on the memory unit 22 is read, a PWM signal having a PWM waveform having a duty ratio equal to the read data is generated.

  The phase distribution circuit unit 24 outputs a PWM signal, an H level signal, and an L level signal output from the PWM signal generation unit 23 with the phase distribution pattern shown in FIG. 2 corresponding to the number of steps indicated by the phase excitation counter unit 25. And the phase-distributed excitation signals A +, A-, / A +, / A-, B +, B-, / B +, / B- with switching elements Q1, Q2, Q3, Q4, Q5, Q6, Q7 , Q8 is turned on and off.

  “PWM (I)”, “PWM (II)”, “PWM (III)”, and “PWM (IV)” in FIG. 2 are “I”, “II”, “III” and “III” shown in FIG. It shows that a PWM signal created by the data group “IV” is assigned. “H” and “L” in FIG. 2 indicate that signals of H level and L level created by the phase distribution circuit unit 24 are assigned. The same applies to FIG. 6, FIG. 9 and FIG. Here, the H level signal means a signal having a voltage level at which the switching element Q1 and the like are completely activated, and the L level signal completely brings the switching element Q1 and the like into an inactive state. A signal having a level voltage.

  The specific operation of the phase distribution circuit unit 24 is as follows.

  When the number of steps of the excitation sequence indicated by the phase excitation counter unit 25 is 0-0, during that period, the PWM signal related to “PWM (I)” shown in FIG. 2 is distributed to the excitation signal A +, and the H level signal Are distributed to the excitation signals / A-, B +, / B-, respectively, and L level signals are respectively distributed to the excitation signals A-, / A +, B-, / B +. In this case, only the switching element Q1 is controlled for each microstep, and the switching elements Q2 to Q8 are in an active state or an inactive state. The same applies to the case where the number of steps of the excitation sequence of the phase excitation counter unit 25 is 0-1, 0-2, 0-3, and only the switching elements Q4, Q2, Q3 are controlled for each microstep, The switching element is in an active state or an inactive state. That is, in the period of the basic step 0, the A phase coil is a current changing phase coil, and the B phase coil is a current maintaining phase coil.

  When the number of steps of the excitation sequence indicated by the phase excitation counter unit 25 is 1-0, during that period, the PWM signal related to “PWM (I)” shown in FIG. 2 is distributed to the excitation signal B +, and the H level signal Are distributed to the excitation signals / B− and / B−, respectively, and L level signals are respectively distributed to the excitation signals A +, A−, / A +, B− and / B +. In this case, only the switching element Q5 is controlled for each microstep, and the switching elements Q2 to Q8 are in an active state or an inactive state. The same applies to the case where the number of steps of the excitation sequence of the phase excitation counter unit 25 is 1-1, 1-2, 1-3, and only the switching elements Q8, Q6, Q7 are controlled for each microstep, Other switching elements are active or inactive. That is, during the basic step 1, the B phase coil is a current change phase coil, and the A phase coil is a current maintaining phase coil.

  In addition, when the number of steps of the excitation sequence indicated by the phase excitation counter unit 25 is 2-0 to 3-3, the distribution is performed in the same manner as described above.

  When the set value of the resolution set value 26 is 0.018 ° as described above, the excitation sequence is sequentially changed to the division steps 0-0, 0-1,. As a result of switching by the excitation signal A + and the like, the magnitudes of currents flowing through the A-phase and B-phase coils of the stepping motor M and the changes thereof are as shown in FIGS. The arrow in FIG. 4 has shown the flow of the electric current of each phase coil. The solid line in the figure is the current related to the current maintenance phase. The broken line shown in the figure is the current related to the current changing phase, and indicates that it is changing every microstep under microstep control.

  In the excitation sequence shown in FIG. 2, when the set value of the resolution setting value 26 is 0.036 °, the excitation sequence is sequentially changed into divided steps 0-0, 0-2, 1-0. When the setting value of the setting value 26 is 0.072 °, the number of decomposition steps changes sequentially as 0-0, 1-0, 2-0, 3-0. The magnitudes of the currents flowing through the A-phase and B-phase coils of the stepping motor M in these cases and the changes thereof are the same as those shown in the corresponding steps of FIGS.

  In the case of the driving apparatus 1 configured as described above, the excitation sequence which is a premise of microstep driving is a 1/4 step excitation pattern, and the number of steps is doubled compared to the conventional stepping motor M. It is possible to further increase the drive resolution. Further, since the switching elements related to the fine current control necessary for the microstep drive are not all phases but only a part, the configuration of the PWM signal generation unit 23 is simplified, and the cost can be reduced. Further, since the duty ratio data of the PWM waveform recorded in the memory unit 22 is finely adjusted for each microstep angle for the entire angle range of the basic step, when the stepping motor M is driven by the microstep, the angle division is performed. Uniformity is maintained, and accordingly, it is possible to increase the accuracy of driving the motor. Therefore, it is very significant in reducing the cost of the entire configuration including the stepping motor M and increasing the resolution of driving of the motor.

  Next, a first modification of the excitation sequence of the drive device 1 will be described with reference to FIGS. The description will focus on differences from the example shown in FIG. 1 and the like, and the description of common parts will be omitted. 6 and 8 correspond to FIGS. 2 and 4 in the above example.

  The excitation sequence employed in the phase distribution circuit unit 24 is as shown in FIG. 6, and the waveforms of the excitation signals at the predetermined timing during the division step 0-0 are as shown in FIG. “PWM” and “/ PWM” in FIG. 6 indicate that two types of PWM signals are assigned. As for the excitation signal related to “PWM”, as shown in FIG. 7, the excitation signal related to “/ PWM” is inverted in a mirror shape with a point at 1 / 2T (T: PWM cycle) as a reference. Yes.

  When the number of steps of the excitation sequence indicated by the phase excitation counter section 25 is 0-0, during that period, the PWM signals of the pattern shown as PWM and / PWM are respectively distributed to the excitation signals A + and A- Signals are distributed to excitation signals / A-, B +, / B-, respectively, and L level signals are distributed to excitation signals / A +, B-, / B +. In this case, the switching elements Q1 and Q2 are controlled for each microstep, and the switching elements Q3 to Q8 are in an active state or an inactive state.

  When the number of steps of the excitation sequence indicated by the phase excitation counter unit 25 is 0-1, the PWM signal of the pattern shown as / PWM and PWM is distributed to the excitation signals A + and A-, respectively, and the H level signal is the excitation signal. The signals are distributed to B + and / B-, respectively, and the L level signal is distributed to the excitation signals A +, A-, B- and / B +. In this case, the switching elements Q3 and Q4 are controlled for each microstep, and the switching elements Q1, Q2, and Q4 to Q8 are in an active state or an inactive state. The same applies to the case where the number of steps of the excitation sequence of the phase excitation counter unit 25 is 0-2, 0-3. Even when the number of steps of the excitation sequence indicated by the phase excitation counter unit 25 is 1-0 to 3-3, the distribution is performed in the same manner as described above.

  The excitation sequence is sequentially changed into divided steps 0-0, 0-1,... And the switching elements Q1 to Q8 are switched by the excitation signal A +. As a result, the A phase and B phase coils of the stepping motor M are switched. FIG. 8 shows the magnitude of the current flowing and the change thereof.

  Since the above-described excitation sequence is employed in the phase distribution circuit unit 24, the memory unit 22, the address generation unit 21, and the PWM signal generation unit 23 also have the following differences. Only the parts different from the above example will be described, and the description of the common parts will be omitted.

  In the memory unit 22, data necessary for creating the waveform of the PWM signal related to “PWM” shown in FIG. 6 is recorded in advance for each microstep angle in the angle region corresponding to the division step. In the example shown in FIG. 3, only a data group corresponding to “I” shown in FIG. 3 is recorded in the memory unit 22.

  The specific operation of the address generator 21 will be described with reference to the example shown in FIG. 3. When the resolution setting value 26 is 0.018 °, 24 (or 25) input pulses α are input. In this process, all data groups corresponding to “I” shown in FIG. 3 are read from the memory unit 22. This is repeated thereafter. When the resolution setting value 26 is 0.036 and 0.072 °, when 12 or 6 input pulses α are input, data corresponding to “I” shown in FIG. A part of the group is read out. This is repeated thereafter. When the direction signal is in the negative direction, it is read out in the opposite manner to the above.

  The specific operation of the PWM signal generation unit 23 will be described using the example shown in FIG. 3. A PWM signal related to “PWM” is generated from the memory unit 22 by a data group corresponding to “I” in FIG. 3. In addition, the PWM signal related to “/ PWM” can be created by the method of inverting the PWM signal in a mirror shape as described above.

  In the case of the driving apparatus 1 according to the first modified example configured as described above, the capacity of the memory unit 22 may be ¼ that of the above example, and the number of data points prepared in advance is small, so that the super high resolution is achieved. There is a great merit in performing micro step drive.

  Next, a second modification of the excitation sequence of the drive device 1 will be described with reference to FIGS. The description will focus on differences from the first modification, and the description of common parts will be omitted. 9 and 10 correspond to FIGS. 6 and 7 in the above example, respectively.

  The excitation sequence adopted in the phase distribution circuit section 24 is as shown in FIG. 9, and the waveforms of the excitation signals at the predetermined timing during the division step 0-0 are as shown in FIG. “Had” and “Lad” in FIG. 9 indicate that a signal having an H level signal or a signal close to an L level signal and having a finely adjusted voltage level is assigned.

  When the number of steps of the excitation sequence indicated by the phase excitation counter unit 25 is 0-0, during the period, the PWM signals having the patterns indicated as “PWM” and “/ PWM” are respectively distributed to the excitation signals A + and A−. , The H level signal is distributed to the excitation signal / A−, the “Had” signal is distributed to the excitation signals B + and / B−, and the L level signal is distributed to the excitation signal / A +. The signals are distributed to excitation signals B− and / B +, respectively. In this case, the switching elements Q1 and Q2 are controlled for each microstep, the switching elements Q3 and Q4 are in an active state or an inactive state, and the switching elements Q5 to Q8 are in an active or inactive state.

  When the number of steps of the excitation sequence indicated by the phase excitation counter unit 25 is 0-1, the PWM signals of the pattern shown as / PWM and PWM are respectively distributed to the excitation signals / A + and / A-, and the L level signal is The excitation signals A + and A− are respectively distributed, the “Had” signal is respectively distributed to the excitation signals B + and / B−, and the “Lad” signal is respectively distributed to the excitation signals B− and / B +. In this case, the switching elements Q3 and Q4 are controlled for each microstep, the switching elements Q1 and Q2 are in an inactive state, and the switching elements Q5 to Q8 are in an active or nearly inactive state. The same applies to the case where the number of steps of the excitation sequence of the phase excitation counter unit 25 is 0-2, 0-3. Even when the number of steps of the excitation sequence indicated by the phase excitation counter unit 25 is 1-0 to 3-3, the distribution is performed in exactly the same manner as described above.

  The excitation sequence is sequentially changed into divided steps 0-0, 0-1,... And the switching elements Q1 to Q8 are switched by the excitation signal A +. As a result, the A phase and B phase coils of the stepping motor M are switched. The magnitude of the current flowing and the change thereof are exactly the same as those shown in FIGS.

  As described above, the phase distribution circuit unit 24 outputs not only H level and L level signals but also “Had” and “Lad” signals as shown in FIG. In this embodiment, the signals “Had” and “Lad” are PWM signals as in “PWM”, but differ from the signals in “PWM” in that the duty ratio is not adjusted for each microstep angle. . The duty ratio of each of the signals “Had” and “Lad” can be adjusted by the current balance adjusting unit 27 shown in FIG.

  The current balance adjustment unit 27 is a switch or the like for finely adjusting the duty ratio of each of the signals “Had” and “Lad”. That is, the duty ratios of the signals “Had” and “Lad” generated by the phase distribution circuit unit 24 through the current balance adjustment unit 27 are finely adjusted. As a result, the A phase coil and B phase coil of the stepping motor M are adjusted. The magnitude of the current related to the current maintenance phase indicated by the solid line in FIG. 8 can be finely adjusted.

  In the case of the drive device 1 according to the second modified example configured as described above, in addition to the above-described effects, the following effects can be obtained. Due to variations in characteristics such as residual magnetic characteristics, winding resistance and inductance of each phase coil of the stepping motor M, and variations in characteristics of the output stage of the driving device 1, the current related to the current changing phase of the stepping motor M and the current maintenance phase are changed. As a result, the desired step angle may not be obtained simply by controlling the current related to the current changing phase. In this regard, in the case of the driving device 1 according to the second modification, since the current related to the current maintenance phase can be finely adjusted in the constant current control, the current related to the current maintenance phase is finely adjusted in the positive or negative direction. Then, according to this, the electric current which concerns on an electric current change phase changes to an opposite direction. This is independent of whether or not the midpoint of the stepping motor M is connected. As a result, the balance between the current related to the current changing phase and the current related to the current maintaining phase can be made appropriate, and as a result, the advance angle at the time of microstep driving becomes accurate. Therefore, it is possible to improve the accuracy of the micro step drive without being greatly affected by the characteristics of the stepping motor M and the variations in the output stage of the drive device 1.

  Next, a driving device 1 according to a third modification will be described with reference to FIGS. 11 and 12. Unlike the above example, the third modification is not a microstep drive, but a full step drive (basic step angle: 1.8 °), a half step drive (half step angle: 0.9 °), and a 1/4 step drive. (¼ step angle: 0.45 °). The description will focus on differences from the example shown in FIG. 1 and the like, and the description of common parts will be omitted. 11 and 12 correspond to FIGS. 2 and 4 of the above example, respectively.

  Of the excitation control unit 20, those corresponding to the address generation unit 21, the memory unit 22, and the PWM signal generation unit 23 are omitted. In this embodiment, the resolution setting unit 26 can be set in three stages of 1.8 ° (full step drive), 0.9 ° (half step drive), and 0.45 ° (1/4 step drive). ing. The excitation sequence employed in the phase distribution circuit unit 24 is as shown in FIG.

  When the set value of the resolution set value 26 is 0.45 °, the phase excitation counter 25 is counted each time the input pulse α is input, and the counted value is determined as the decomposition steps 0-0, 0-1, 0-2. , 0-3, 1-0... 3-3 are sequentially shown. This is repeated thereafter. When the excitation sequence changes sequentially as described above and the switching elements Q1 to Q8 are switched according to the excitation signal A +, etc., the magnitude of the current flowing through the A-phase and B-phase coils of the stepping motor M and its change are as follows. As shown in FIG.

  When the set value of the resolution setting value 26 is 0.9 °, the phase excitation counter 25 is counted each time the input pulse α is input, and the counted value is determined as the decomposition steps 0-0, 0-2, 0-2. , 1-0, 1-2... 3-2 are sequentially shown. This is repeated thereafter. When the set value of the resolution setting value 26 is 1.8 °, the phase excitation counter 25 is counted each time the input pulse α is input, and the counted value is determined as the decomposition steps 0-0, 1-0, 2-0. , 3-0 sequentially. This is repeated thereafter. When the excitation sequence is sequentially changed as described above and the switching elements Q1 to Q8 are switched in accordance with the excitation signal A + or the like, the magnitude of current flowing through the A-phase and B-phase coils of the stepping motor M and the change thereof are as follows. This is the same as that shown in the corresponding step of FIG.

  In the case of the driving apparatus 1 according to the third modification configured as described above, the stepping motor M can be driven with a 1/4 step excitation pattern, and basically only the excitation sequence needs to be changed. It can be realized easily. Therefore, it is significant in reducing the cost of the entire configuration including the motor M 1 and increasing the drive resolution of the motor.

  The two-phase stepping motor driving apparatus according to the present invention is applicable to two-phase as long as it has a coil connection structure in which the middle point a of the A-phase coil and the middle point b of the B-phase coil are electrically connected to each other in common. The type of stepping motor is not questioned. About a switching part, as long as it is a bipolar type which produces | generates each electric current which flows into the A phase and B phase coil of the motor, a circuit structure is not ask | required. The configuration of the excitation control unit is not limited as long as each switching element configuring the switching unit according to the input pulse is configured to be turned on and off in a predetermined pattern for each divided step obtained by dividing the basic step into four. The settable range of the resolution setting unit, the type of the constant current control method, and the like may be appropriately changed.

1 Drive device (2-phase stepping motor drive device)
10 Switching section
20 Current controller
21 Address generation unit 22 Memory unit 23 PWM signal generation unit 24 Phase distribution circuit unit M Stepping motor (two-phase stepping motor)

Claims (5)

  The midpoint a between the positive terminal A and the negative terminal / A of the A phase coil and the midpoint b between the positive terminal B and the negative terminal / B of the B phase coil are electrically connected to each other in common. A device for driving a two-phase stepping motor having a coil connection structure, wherein a bipolar type switching unit for generating currents flowing in the A-phase and B-phase coils of the motor and a switching unit according to an input pulse are configured. Each of the switching elements to be turned on and off in a predetermined pattern for each divided step obtained by dividing the basic step into four, and the excitation controller flows to the A-phase coil during the period of (1) basic step n The current is sequentially changed from the positive direction to the negative direction, the current flowing through the B-phase coil is maintained at the H level in the positive direction, and the current flowing through the A-phase coil is maintained at the negative H level at the basic step n + 1. The current flowing in the B-phase coil is sequentially changed from the positive direction to the negative direction, the current flowing in the A-phase coil is sequentially changed from the negative direction to the positive direction in the basic step n + 2, and the current flowing in the B-phase coil is negatively changed. The current flowing through the A phase coil at the basic step n + 3 is maintained at the H level in the positive direction, and the current flowing through the B phase coil is sequentially changed from the negative direction to the positive direction. (2) In the process of changing the current flowing through the A-phase coil from the positive direction to the negative direction, the intermediate point a is changed from the middle point b through the middle point b to the negative terminal / A, and similarly from the middle point a to the positive terminal A sequentially. In the process of changing the current flowing in the A-phase coil from the negative direction to the positive direction, the middle point a is changed from the middle point b to the positive terminal A in the same way. Sequential to side terminal / A In the process of changing the current flowing in the B-phase coil from the positive direction to the negative direction while allowing the current to flow, the middle point b is similarly changed from the middle point b to the negative terminal / B through the middle point a of the A-phase coil. In the process of causing current to flow sequentially from the positive terminal B to the positive terminal B and changing the current flowing through the B phase coil from the negative direction to the positive direction, the middle point b is changed from the middle point a to the positive terminal B. Similarly, the two-phase stepping motor driving device is configured such that current flows sequentially from the middle point b to the negative terminal / B.   2. The two-phase stepping motor driving apparatus according to claim 1, wherein the two-phase stepping motor is driven by microstep driving, wherein the current is maintained at the H level or the L level during the basic step of the A phase and B phase coils. When the coil is a current sustaining phase coil and the current changing phase coil is a current changing phase coil during the basic step, the excitation control unit is configured to switch some of the switching elements related to the current changing phase coil. A two-phase stepping motor characterized in that the switching element is controlled for each micro step during the division step and the other switching elements are made active or inactive during the division step. Drive device.   3. The two-phase stepping motor drive device according to claim 2, wherein the excitation control unit has a duty of a PWM waveform necessary for pulse width modulation (PWM) control of an output current of a part of the switching elements related to the current change phase coil. A memory unit in which ratio data is recorded in advance for each microstep angle, an address generation unit that sequentially reads data on the memory unit according to an input pulse, and a PWM signal generation that generates a PWM signal based on the data on the memory unit A phase excitation counter that calculates the number of steps in the excitation sequence by counting the input pulses, a PWM signal output from the PWM signal generator with a phase distribution pattern corresponding to the number of steps indicated by the phase excitation counter, The H level signal and the L level signal are phase-distributed and the switching unit is controlled by the phase-distributed signal. A two-phase stepping motor drive device characterized by comprising a phase distribution circuit section for turning on and off each switching element.   3. The two-phase stepping motor driving apparatus according to claim 2, wherein the excitation control unit has a small current value of H level and L level when other switching elements are in an active state and an inactive state. A two-phase stepping motor driving device characterized in that it has an adjustable configuration.   4. The two-phase stepping motor driving apparatus according to claim 3, wherein the memory unit stores PWM waveform duty ratio data so that the stepping motor can be micro-step driven in units of angles obtained by equally dividing a basic step angle. A two-phase stepping motor drive device, wherein the basic step angle or the divided step angle range is finely adjusted for each micro step angle.

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