JP3365089B2 - Driving device for stepping motor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving device for a stepping motor, and more particularly to a driving device for a stepping motor for reducing vibration and noise. 2. Description of the Related Art A conventional driving device for a stepping motor is disclosed, for example, in Japanese Patent Application Laid-Open No. 63-174592. The stepping motor driving device includes a selection circuit that switches the A-phase, B-phase, A (bar) phase, and B (bar) phase excitation coils with time, and selects a one-phase or two-phase excitation coil. A current setting circuit for setting the current value of the excitation current supplied to the excitation coil of the selected phase, and the excitation of the current value set by the current setting circuit for the one-phase or two-phase excitation coil selected by the selection circuit It is constituted by an excitation circuit that supplies a current and drives a stepping motor. A current setting circuit configured to connect a first to a fifth resistor in series; a first series resistor circuit;
A second series resistor circuit in which sixth to tenth resistors are connected in series; one end of the first and second series resistor circuits is commonly grounded via an eleventh resistor, and the other end is connected to the other end; Connected to a fixed potential power supply. [0003] In the above configuration, the selection circuit is A-phase, A-phase
Phase and B phase, B phase, B phase and A (bar) phase, A (bar) phase, A (bar) phase and B (bar) phase, B (bar)
The excitation coils are selected in a predetermined rotation order such as a phase. At the same time, the current setting circuit sets the first reference point of the first reference resistance point to the ground potential in the predetermined series for the excitation coils of the A-phase and the A (bar) phase in a predetermined order. The changing voltage division value is read, a current value corresponding to the voltage division value is set, and the second series resistance circuit of the second series resistance circuit is set for the B-phase and B (bar) -phase excitation coils. The voltage division value is read from the reference point in the same manner, and a current value corresponding to the voltage division value is set. The excitation circuit supplies an excitation current having a current value set with time by the current setting circuit to the one-phase or two-phase excitation coil selected by the selection circuit to drive the stepping motor. At this time, the current setting circuit sets the excitation vector when driven by the one-phase excitation coil and the excitation vector when driven by the two-phase excitation coil by setting the resistance value of each resistor as described above. Set the current value of the excitation current. This makes the rotation of the stepping motor smooth, and reduces vibration and noise. However, according to the conventional stepping motor driving apparatus, the rotor is determined by the exciting current during low-speed driving, for example, in the two-phase excitation state of A-phase and B-phase. After a positional deviation from the step angle corresponding to the phase angle, and a minute vibration is repeated near the step angle, the rotation is shifted to the next step angle. For this reason, the reduction of vibration at the time of low-speed driving and the accompanying noise is insufficient. Accordingly, it is an object of the present invention to reduce vibration and noise by appropriately shifting the rotor to a step angle corresponding to a phase angle determined by an exciting current in a two-phase excitation state at the time of low-speed driving. An object of the present invention is to provide a motor driving device. According to the present invention, in order to achieve the above object, one-phase and two-phase excitation coils are periodically selected in a predetermined order from a plurality of phase excitation coils, and the selection is made. A stepping motor driving device for driving the stepping motor by supplying an exciting current having a predetermined current value so that the lengths of the exciting vectors become equal to the excited exciting coils. Selection means for selecting the one-phase and two-phase excitation coils; current setting means for setting the predetermined current value; and the current setting means for the one-phase and two-phase excitation coils selected by the selection means Excitation means for supplying the excitation current having the predetermined current value set by the first current control means, wherein the current setting means determines a first current determined by an excitation current supplied to the two-phase excitation coil. The first phase angle magnetic vector is first determined by the excitation current at the time of each single-phase excitation of the exciting coils of the two phases 2
And when the phase angle is smaller than a fourth phase angle corresponding to a half of the phase difference between the second and third phase angles of the third excitation vector, the first phase angle is set to the second phase angle. An exciting current supplied to the two-phase exciting coil is set so as to be smaller than a fifth phase angle corresponding to a phase difference of a half of a phase difference between the first phase angle and the fourth phase angle; Is larger than the fourth phase angle, the first phase angle is
1/2 of the phase difference between the fourth phase angle and the third phase angle
A step of setting the exciting current supplied to the two-phase exciting coil so as to be larger than a sixth phase angle corresponding to the phase difference of the stepping motor. For example, three phase angles based on two-phase excitation are provided between one-phase excitation of phase A and one-phase excitation of phase B, and the three phase angles correspond to the three phase angles by the magnetic field generated by the excitation current. 3
Rotate the rotor to one step angle. At this time, the first
Is usually 90 ° × １ ／ = 22.5 °
However, by increasing the ratio of the excitation current of the A phase to the excitation current of the B phase, for example, 17.0 ° (22.5 °)
-5.5 °). The second phase angle is usually 9
0 ° × ２ = 45 °. On the other hand, the third phase angle is
Normally, 90 ° × 3/4 = 67.5 °,
This is increased by increasing the ratio of the B-phase excitation current to the A-phase excitation current, for example, 73.0 ° (67.5 ° + 5.5).
°). When the stepping motor was driven under these driving conditions, the displacement from the step angle corresponding to the phase angle of the rotor was reduced, thereby reducing the amplitude of minute vibrations generated near the step angle and reducing noise. . FIG. 1 shows an embodiment of a driving device for a stepping motor according to the present invention, in which an exciting coil 5A and a rotor 5B are provided.
And a circuit configuration for reducing vibration and noise when the motor 5 is driven at a low speed. The current setting circuit 1 has an A phase and an A
The (bar) phase reference signal Vref ₁ and the B and B (bar) phase reference signals Vref ₂ are input to input the A phase, B phase, and A phase.
The selection circuit 2 outputs current value signals of the (bar) phase and the B (bar) phase.
Phase, phase B, phase B and phase A (bar), phase A (bar), phase A
The phase of the excitation coil is selected for one-phase excitation and two-phase excitation in the order of (bar) phase and B (bar) phase, B (bar) phase, B (bar) phase, A phase, and A phase. Yes,
The excitation circuit 3 supplies an excitation current of the current value set by the current setting circuit 1 to the one-phase or two-phase excitation coil 5A selected by the selection circuit 2, and the control unit 4 outputs a start signal START. Input current setting circuit 1,
The control circuit controls the selection circuit 2 and the excitation circuit 3.
The current setting circuit 1 outputs output terminals C1 and C2 that output a ground potential signal of "1" in synchronization with the clock signal.
And the C3, the output terminal A for outputting a current value signal described above, B, A ¯ and B and (bar), the input terminal V for inputting a reference signal Vref ₁ and Vref ₂ described above
with a ref ₁ and Vref _2. Input terminal Vref
₁ and Vref ₂ is connected to the connection point N _A and N _B of the capacitor C _A and C _B series resistor group R1~R5 and R7 to R10, the output terminal C1~C3 the node A ₁ between the series resistor group resistance to a ₃ and B ₁ .about.B inverter I ₃ the output terminal is connected to the ₃ and I _4, I ₂ and I _5, and is connected to an input terminal of the I ₁ and I _6, the output terminal a, B, a ( Bar) and B (bar) are connected to three input terminals A, B, A (bar) and B (bar) of the excitation circuit, respectively. Series resistance groups R1 to R5 and R7 to R
10 are connected in common at node N _C and N _D, the power supply Vcc node N _C via the inverter I ₇ (a fixed potential, e.g., + 5V) is set to always ground potential by being connected to the node N _D is connected to the power source Vcc through a resistor R _11. The operation of the above configuration will be described below. In FIG. 2, when a clock signal t ₀ is output, the selection circuit 2 selects a B (bar) phase excitation coil (hereinafter, simply referred to as a B (bar) phase), and the current setting circuit 1 selects from C1 to C3. Both output a ground potential signal of "0". Sum of the potential of the resistor node N _B to the (R
First becomes a potential determined in proportion to the 7 + R8 + R9 + R10) , is input to the current setting circuit 1 as a reference signal Vref _2. As a result, an exciting current having a first current value corresponding to the first potential is supplied from the exciting circuit 3 to the B (bar) phase.
The first current value is the maximum value level of the stepped current waveform shown in FIG. When the clock signal t ₁ is output, the selection circuit 2 selects an A-phase exciting coil (hereinafter, simply referred to as A-phase), and the current setting circuit 1 outputs a “0” ground potential signal from the output terminals C1 and C2. And outputs a ground potential signal of "1" from the output terminal C3. As a result, the reference signal Vre
f ₁ becomes the fourth potential that is proportional to the resistance R2, Vref
₂ is a second potential proportional to the sum of the resistors (R7 + R8 + R9). As a result, the excitation current having the fourth current value (the fourth current level in the step-like current waveform) is supplied to the A phase, and the second current value (the second current level in the step-like current waveform) is supplied to the B (bar) phase. (A current level). Thereafter, when the clock signals t ₂ and t ₃ are output, the excitation current of the A phase increases stepwise, and the excitation current of the B (bar) phase decreases stepwise. Next, when the clock signal t ₄ is output, the selection circuit 2 select the A-phase, the current setting circuit 1 outputs a ground potential signal of "0" from the output terminal C1 to C3. Therefore, the reference signal Vref ₁ is the sum of the resistance (R2 + R
3 + R4 + R5), and the first potential flows in the A phase. In FIG. 3, A
The phase excitation vector is denoted by A. Next, the clock signal t
₅ is output, the A phase and the B phase are selected, and the output terminal C
A ground potential signal of 1 to “1” is output, and a ground potential signal of “0” is output from the output terminals C2 and C3. Therefore, the reference signal Vref ₁ sum of the resistance (R2 + R3 + R
4) becomes a second potential proportional to the reference signal Vref ₂
Becomes a fourth potential proportional to the resistance R7. As a result, as shown in FIG. 2, the excitation current having the second current value indicated by 'is supplied to the A phase, and the excitation current having the fourth current value indicated by' is supplied to the B phase. . At this time, the phase angle θ ₁ of the excitation vector becomes' as shown in FIG. The phase angle of the excitation vector ′ is set to 17.0 ° (=
22.5 °-5.5 °). On the other hand, according to the conventional stepping motor driving device, the phase A and the phase B
The phase excitation current is set as shown by the broken line in FIG. 2, and the phase angle θ ₂ of the excitation vector at this time is set to 22.5 ° (= 90 ° × １ ／) as shown in FIG. are doing. Next, when the clock signal t ₆ is output, and then continue with the selection of the A-phase and B-phase, also the output terminals C1 and C3 outputs a ground potential signal of "0", the output terminal C2 is "1 Is output. Thus, the third reference signal Vref ₁ is proportional to the sum of the resistances (R2 + R3)
, And the reference signal Vref ₂ is the sum of the resistances (R7 +
The third potential is proportional to R8). As a result, the A-phase and B-phase excitation currents are:
Both have the third current value, and the excitation vector has a phase angle θ ₃ of 45 ° (= 90 ° × ２) as shown by FIG. Next, when the clock signal t ₇ are output in the same way, and then continue with the selection of the A-phase and B-phase, also the output terminals C1 and C2 outputs a ground potential signal of "0", the output terminal C3 outputs a ground potential signal of "1". Therefore, the reference signal Vref ₁ is equal to the resistance R
2 and the reference signal Vref ₂ becomes a second potential proportional to the sum of the resistors (R7 + R8 + R9). As a result, the excitation current of the A-phase has a fourth current value as indicated by 'in FIG. 2, and the excitation current of the B-phase has a second current value as indicated by' in FIG. At this time, the phase angle of the excitation vector is set to θ ₅ , and the resistance values of the series resistance groups R1 to R5 and R6 to R10 are set to 73.0 ° as indicated by 'in FIG.
(= 67.5 ° + 5.5 °). On the other hand, according to the conventional stepping motor driving apparatus, the excitation currents of the A-phase and the B-phase are set as shown by the broken lines in FIG. 2, and the excitation vector at this time is set to 67.5 as shown in FIG. is set to the phase angle theta ₄ of ° (= 90 ° × 3/ 4). Next, when the clock signal t ₈ is output,
Only the phase B is selected, the ground potential signals of the output terminals C1 to C3 become "0", the exciting current of the phase B becomes the first current value as shown by B in FIG.
As shown by B in FIG.
This operation is periodically repeated in response to the output of the clock signals t ₉ , t ₁₀ , t ₁₁ }, and the stepping motor 5 operates at a speed corresponding to the frequency of the clock signals t ₀ , t ₁ , t ₂ }. Driven. In the above embodiments, the excitation current of phase A during the output of the clock signal t ₅ 'is, I _a cos17 °, and the excitation current of phase B' is a I _b sin17 °. Here, _Ia and _Ib are the exciting currents of the first current values of the A phase and the B phase. Similarly, the excitation current of the A-phase at the time of outputting the clock signal t ₇ is I _a cos 73 °, and the excitation current of the B-phase is I _b sin 73 °. In FIG. 2, when the stepping motor 5 was driven by the exciting current having the stepped waveform represented by the solid line as in the example, the noise level was 72.5 dBA. On the other hand, when the stepping motor 5 was driven by the exciting current having a step-like waveform partially shown by a broken line, the noise level was 77.4 dBA. As a result, the effect of reducing the vibration and the accompanying noise according to the present invention was confirmed. FIGS. 4 and 5 show the step angle when the rotor 5B rotates with respect to time (millisecond), and the waveform shows the vibration of the rotor 5B. The rotation direction was clockwise, one step angle was 0.45 °, and the clock signal was 20 pps (pulses / second). FIG. 4 is of the present invention, and FIG. 5 is of the prior art. FIG. 6 is obtained by superposing FIGS. 4 and 5 on the same time axis, and the present invention has a vibration amplitude smaller than that of the related art,
In addition, the one-step angle is close to 0.45 °, indicating that they are equal. 7 and 8 show an error angle (vertical axis) which is a deviation from an ideal position with respect to a step angle (horizontal axis) of 40 samples. FIG. 7 shows an example of the present invention, and FIG. is there. In the present invention, a maximum error of 0.05 ° was observed for the 25th sample. On the other hand, conventionally, a maximum error of 0.14 ° was observed in the fifteenth sample. 9 and 10 show time (milliseconds)
, The step angle at the time of rotation of the rotor 5B, the clock signal is 500 pps, and the step angle range is 1
Except for 8.0 ° to 22.5 °, they are common to FIGS. 4 and 5. FIG. 9 shows the present invention, in which the swell (ripple) is smaller than that of the conventional one shown in FIG. 1 from FIG.
4 differs from FIG. 4, FIG. 5, FIG. 9, and FIG. 10 in the range of time and step angle, but is common in that the vibration of the rotor 5B is observed. (1) FIG. 11 (present invention) Step angle 0.45 ° Clock signal 1000 pps (2) FIG. 12 (conventional) step angle Same clock signal as FIG. 11 (3) FIG. 13 (present invention) Step angle 0 .45 ° clock signal 2000 pps (4) FIG. 14 (conventional) step angle Same clock signal as FIG. 13 Same as FIG. 13 FIG.
At rotational speeds above pps, no difference in vibration was observed between the present invention and the conventional one. As described above, according to the stepping motor driving apparatus of the present invention, the phase angle determined by the exciting current in the two-phase excitation state at the time of low-speed driving is, for example, 45 ° or less. When the phase angle is smaller than the phase angle generally set conventionally, and when the phase angle is 45 ° or more, it is larger than the phase angle generally set conventionally, the vibration and noise of the stepping motor are reduced. be able to.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a configuration of one embodiment of the present invention. FIG. 2 is a timing chart showing a current waveform in the operation of one embodiment of the present invention. FIG. 3 is a vector diagram showing a phase of an excitation vector by an excitation current according to the present invention. FIG. 4 is a graph showing a step angle of the rotor of the present invention. FIG. 5 is a graph showing a step angle of a rotor of a conventional driving device for a stepping motor. FIG. 6 is a graph showing a step angle of a rotor of a driving device for a stepping motor according to the present invention and a conventional one. FIG. 7 is a graph showing a step angle error of the rotor of the present invention. FIG. 8 is a graph showing a step angle error of a rotor of a conventional driving device for a stepping motor. FIG. 9 is a graph showing a step angle of the rotor of the present invention. FIG. 10 is a graph showing a step angle of a rotor of a conventional driving device for a stepping motor. FIG. 11 is a graph showing a step angle of the rotor of the present invention. FIG. 12 is a graph showing a step angle of a rotor of a conventional driving device for a stepping motor. FIG. 13 is a graph showing a step angle of the rotor of the present invention. FIG. 14 is a graph showing a step angle of a rotor of a conventional driving device for a stepping motor. [Description of Reference Numerals] 1 current setting circuit 2 select circuit 3 excitation circuit 4 control unit 5 motor 5A exciting coil 5B rotor R1~R11 resistance I ₁ ~I ₇ inverters C _A, C _B capacitor Vcc power supply

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-270696 (JP, A) JP-A-2-32797 (JP, A) JP-A 4-150795 (JP, A) JP-A-63-1988 174592 (JP, A) JP-A-61-218400 (JP, A) JP-A-63-171197 (JP, A) JP-A-1-298996 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02P 8/00

Claims (1)

(57) [Claim 1] One-phase and two-phase excitation coils are periodically selected in a predetermined order from a plurality of phases of excitation coils, and the lengths of excitation vectors are selected by the selected excitation coils. A stepping motor driving device that drives an stepping motor by supplying an exciting current having a predetermined current value so that the excitation coils of the one-phase and two-phase excitation coils are periodically arranged in the predetermined order. Selecting means for selecting the current value; current setting means for setting the predetermined current value; and the predetermined current value set by the current setting means for the one-phase and two-phase excitation coils selected by the selecting means. Exciting means for supplying the exciting current of the two-phase exciting coil, wherein the first phase angle of the first exciting vector determined by the exciting current supplied to the two-phase exciting coil, From a fourth phase angle corresponding to a half of the phase difference between the second and third phase angles of the second and third excitation vectors determined by the exciting current at the time of single-phase excitation of the exciting coil, respectively. When the first phase angle is smaller than the fifth phase angle, the first phase angle is smaller than a fifth phase angle corresponding to a half of the phase difference between the second phase angle and the fourth phase angle. When the first phase angle is larger than the fourth phase angle,
The two-phase excitation coil so that the first phase angle is larger than a sixth phase angle corresponding to a half of a phase difference between the fourth phase angle and the third phase angle. A driving device for a stepping motor, characterized by having a configuration for setting an exciting current supplied to the motor.