JP4166327B2 - Stepping motor apparatus having a position sensor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a stepping motor device that includes a rotor position sensor in a stepping motor and suppresses vibration of the rotor of the stepping motor during operation.
[0002]
[Prior art]
Conventionally, this kind of stepping motor is controlled by rotating the magnetic field of the stator (hereinafter referred to as a rotating magnetic field) and causing the rotor to follow the rotating magnetic field by attracting and repelling the magnetic force. Rotational force is generated. A popular stepping motor has a multi-pole such as 50 rotor teeth, but a simple two-pole stepping motor is shown in FIG.
[0003]
In FIG. 4, an alternating current is passed through the stator winding A phase and the stator winding B phase wound around the magnetic poles of the two-pole stepping motor M, and generated by the respective stator windings. A rotating magnetic field is formed by synthesizing an A phase magnetic field and a B phase magnetic field having a phase difference of 90 degrees from each other. The rotating magnetic field is rotated so that the rotor magnetized to a predetermined polarity follows to generate a mechanical rotational force.
[0004]
[Problems to be solved by the invention]
However, there has been a problem that the rotor often vibrates during the normal operation of the conventional stepping motor M. The following factors can be considered as the cause of the vibration.
(A) Torque ripple and inertia resonance (b) Effects of sampling control time interval roughness (c) Other unknown factors
That is, the stepping motor M may suddenly increase in vibration in a certain speed region or the output torque may drop. In some cases, reverse rotation and misstep occur. These phenomena occur when the frequency of the input pulse matches the natural frequency of the motor in the low speed region.
The conditions under which such resonance occurs vary depending on the frictional load, inertial load, and the like, but generally, the vicinity of 100 to 250 pps is the resonance region in the low speed region. It also occurs in the high speed region due to other factors. When resonance becomes a problem, it has been used in the 1-2 phase excitation method or measures are taken on a mechanical damper or a drive circuit, but this is not sufficient.
[0006]
The present invention has been made in view of such a point, and an object thereof is to provide a stepping motor device including a position sensor that eliminates the above-described problems and suppresses vibrations generated in a rotor during operation. .
[0007]
[Means for Solving the Problems]
The configuration of the apparatus of the present invention for achieving the above object is a stepping motor including a position sensor 2, which demodulates a rotor position detection signal output from the position sensor via a demodulator. Are input to one input terminal of the microcomputer 4, and the microcomputer converts the demodulated position detection signal and the position command signal input to the other input terminal into respective speed signals, and converts the respective speed signals. Based on the difference between the two signals after applying a low-pass filter to the signal , a correction amount of the excitation phase of the stator pole of the motor is calculated, and a signal obtained by adding the calculated correction amount to the position command signal is calculated. output, its output signal, via an amplifier, and supplied to the motor as the excitation current is a stepping motor device including a position sensor which comprises suppressing vibration during operation of the motor
[0008]
The microcomputer 4 includes a speed command unit 4a having a low-pass filter 4h that uses the position command signal as a speed command signal, and a speed detection unit that includes a low-pass filter 4h that uses the position detection signal as a speed detection signal. 4b, a subtraction unit 4c that takes the difference between the speed command signal from the speed command unit 4a and the speed detection signal from the speed detection unit 4b, and the difference signal as an excitation phase correction amount. Multiplication unit 4d for multiplying the coefficient, and step-out prevention for switching to either the position command signal side (ST mode (stepping motor mode) side) or the position detection signal side (BL mode (brushless motor mode) side) By switching between the switch 4f and the step-out prevention switch 4f, an output signal as a correction of the excitation phase from the multiplication unit 4d is passed through the step-out prevention switch 4f. And an addition unit 4e that outputs an excitation phase signal for exciting the motor in addition to either the position command signal or the position detection signal, and the position sensor detects the rotor of the motor. A stepping motor device comprising a position sensor that detects vibration and outputs the excitation phase signal so that the microcomputer adds the correction amount of the excitation phase to either the position command signal or the position detection signal. is there.
[0009]
The microcomputer 4 further includes a switching control unit 4j for switching the step-out prevention switch 4f, and the switching control unit allows a deviation amount between the position command signal and the position detection signal to be changed.
(A) If −90 ° ≦ deviation amount ≦ + 90 °, switch to the position command signal side (ST mode side)
(B) In the case of -90 [deg.]> Deviation amount and +90 [deg.] <Deviation amount, the stepping motor device includes a position sensor that switches to the position detection signal side (BL mode side) .
[0011]
Since the present invention is configured as described above, the vibration of the rotor of the motor is detected by the position sensor assembled in the stepping motor, and the excitation phase of the motor is corrected by the microcomputer. I have to.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, exemplary embodiments of the invention will be described in detail with reference to the drawings. 1 and 2 are diagrams showing an embodiment of a stepping motor device having a position sensor according to the present invention. FIG. 1 is a configuration diagram showing a circuit including a stepping motor and a microcomputer in which the position sensor is assembled. These are the figures which show the structure control block in a microcomputer which corrects an excitation phase by negatively feeding back the detection signal from a position sensor to the microcomputer side.
[0013]
In FIG. 1, a variable reluctance type (hereinafter referred to as VR type) resolver is coupled to a stepping motor (for example, two-phase) 1 as a position sensor 2 for detecting the operating position of the rotor. The position detection signal of the rotor of the motor 1 output from the sensor 2 is demodulated by the demodulator 3 and input to one input terminal of the microcomputer (microcomputer or central processing unit) 4. A position command signal is input to the other input terminal of the microcomputer 4 from a position setter (not shown).
[0014]
In the microcomputer 4, the respective speeds are obtained from the demodulated position detection signal from the demodulator 3 and the position command signal, and the rotation generated by the stator magnetic poles of the motor 1 due to the difference between the respective speeds. A magnetic field angle, that is, an excitation phase correction is calculated, the excitation phase correction is added to the position command signal, and is output as an excitation phase signal for exciting the motor 1.
The output signal from the microcomputer 4, that is, the excitation phase signal for exciting the motor 1 is amplified by a power amplifier 5 and supplied to the motor 1 as an excitation current (for example, two phases). .
[0015]
In this case, since the torque ripple of the motor 1 depends on the period of the number of teeth of the rotor, the position sensor 2 needs a high resolution in order to correspond to the torque ripple. For this reason, the VR type resolver is adopted for the position sensor 2, and the resolver has the same number of poles as the number of teeth of the rotor, and ensures high resolution.
[0016]
Next, the main operation of the present embodiment will be described with reference to FIG.
The microcomputer 4 includes a speed command unit 4a that uses the position command signal as a speed command signal, a speed detection unit 4b that uses the position detection signal from the position sensor 2 as a speed detection signal, and a speed command unit 4a A subtraction unit 4c that takes the difference between the speed command signal and the speed detection signal from the speed detection unit 4b, a multiplication unit 4d that multiplies the difference signal by a coefficient described later, and an output signal from the multiplication unit 4d (the excitation signal) Is added to the position command signal via the step-out prevention switch 4f (injected into the ST mode (stepping motor mode) side), and an excitation phase signal for exciting the motor 1 is output. And an out-of-step prevention switch 4f. The step-out prevention switch 4f is normally turned on to the ST mode side.
[0017]
Furthermore, the addition unit 4e the output signal from the multiplication section 4d (correction amount of the excitation phase), through a dehydration tone prevention switch 4f (BL mode (input to the brushless motor mode) side), the position In addition to the detection signal, an excitation phase signal for exciting the motor 1 is output.
[0018]
Regarding the step-out prevention switch 4f, in the microcomputer 4, the deviation between the position command signal and the position detection signal is monitored by the switching control unit 4j, and the step-out prevention switch 4f is determined by the deviation amount (electrical angle). The prevention switch 4f is switched between the ST mode (stepping motor mode) and the BL mode (brushless motor mode). That is,
(A) When −90 ° ≦ deviation amount ≦ + 90 °, the ST mode is set and the excitation state of the motor winding is switched. So-called open loop control is used.
(B) When −90 °> deviation amount and + 90 ° <deviation amount, the BL mode is set and excitation is performed so that the excitation current phase is an excitation stable point 90 ° ahead of the rotor position. So-called closed loop control is used.
By switching the step-out prevention switch 4f by the switching control unit 4j, the rotor of the motor 1 can follow the position command signal without stepping out and can be positioned.
[0019]
In the present embodiment, the original control by the microcomputer 4 is to control the motor 1 at time intervals at a constant unit time Δt interval. This time step is performed in the difference extraction unit 4g as follows.
... t _in , t _in-1 , ..., t _i-3 , t _i-2 , t _i-1 , t _i , ...
Here, at time t _i-1 and t _i , the position detection signal from the resolver as the position sensor 2 becomes x _i-1 and x _i at the speed detection unit 4b. The difference Δx _i at the position time interval Δt corresponds to the speed of the rotor at time t _i .
That is, Δx _i = x _i −x _i−1 .
Furthermore, in order to reduce the influence of detection accuracy, a signal obtained by applying a low- pass filter 4h is defined as a speed detection signal _VFB .
[0020]
The speed command signal V _CMD is also obtained by applying a low- pass filter 4h to the position command signal that has been processed by the speed command unit 4a equivalent to the difference extraction unit 4g of the speed detection unit 4b. .
Then, the difference between the speed detection signal V _FB and the speed command signal V _CMD, by multiplying the K _D as the coefficient correction amount P _D of the exciting phase, _{i.e., P D = K D (V} CMD - V _FB ) is added to the position command signal to form an excitation phase signal for the motor 1.
[0021]
In this case, since the speed detection is reflected in the microcomputer 4 in an inverted manner, the excitation phase of the rotating magnetic field is advanced in the direction in which the excitation phase of the rotating magnetic field is delayed with respect to the excessive speed, and the excitation phase of the rotating magnetic field is advanced with respect to insufficient speed. The direction is controlled. Thereby, the vibration of the rotor of the stepping motor 1 can be suppressed.
FIG. 3 is a diagram showing the torque with respect to the phase angle when the excitation phase is controlled. By utilizing this phase angle-torque characteristic, the vibration suppression control of the rotor can be performed.
[0022]
Note that the technology of the present invention is not limited to the technology in the above-described embodiment, and may be implemented by means of other modes that perform the same function, and the technology of the present invention may be variously modified within the scope of the above-described configuration. Can be added.
[0023]
【The invention's effect】
As is apparent from the above description, according to the stepping motor apparatus including the position sensor of the present invention, the stepping motor includes a rotor position sensor, and the rotor position of the motor output from the position sensor is determined. A detection signal is input to one input terminal of the microcomputer, a position command signal is input to the other input terminal of the microcomputer, and the microcomputer outputs an excitation phase signal for exciting the motor from the microcomputer, The vibration of the rotor of the motor is detected by the position sensor, and the excitation phase signal is output by the microcomputer so as to add the correction amount of the excitation phase to the position command signal. Since an excitation current is supplied to the motor, vibration generated in the rotor can be suppressed during operation of the motor.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing a circuit including a stepping motor and a microcomputer incorporating a position sensor according to an embodiment of the present invention.
FIG. 2 is a diagram showing a control block in a microcomputer that negatively feeds back a detection signal from a position sensor to the microcomputer side to apply excitation phase correction.
FIG. 3 is a diagram illustrating a torque characteristic with respect to a phase angle when the excitation phase of the stepping motor is controlled.
FIG. 4 is an explanatory diagram showing a model of a two-pole stepping motor.
[Explanation of symbols]
1 Stepping motor 2 Position sensor (variable reluctance type resolver)
3 Demodulator 4 Microcomputer 4a Speed command section 4b Speed detection section 4c Subtraction section 4d Multiplication section 4e Addition section 4f Step-out prevention switch 4g Difference extraction section 4h Low- pass filter 5 Power amplifier

Claims (3)

A stepping motor comprising a position sensor,
The rotor position detection signal output from the position sensor is demodulated via a demodulator and input to one input terminal of the microcomputer. The microcomputer detects the demodulated position detection signal and the other signal. The position command signal input to the input terminal is converted into each speed signal, and after the low-pass filter is applied to each speed signal, the excitation phase of the stator magnetic pole of the motor is determined by the difference between the two signals . Calculate a correction amount, and output a signal obtained by adding the calculated correction amount to the position command signal ,
A stepping motor device provided with a position sensor, wherein the output signal is supplied to the motor as an excitation current via an amplifier to suppress vibration during operation of the motor. The microcomputer is
A speed command unit including a low-pass filter, which makes the position command signal a speed command signal;
A speed detection unit including a low-pass filter that converts the position detection signal into a speed detection signal;
A subtraction unit that takes a difference between the speed command signal from the speed command unit and the speed detection signal from the speed detection unit;
A multiplication unit for multiplying the difference signal by a coefficient as a correction amount of the excitation phase;
A step-out prevention switch for switching to either the position command signal side or the position detection signal side;
By switching the step-out prevention switch, the output signal as the correction of the excitation phase from the multiplication unit is added to either the position command signal or the position detection signal through the step-out prevention switch. An adder for outputting an excitation phase signal for exciting the motor;
Consisting of
The vibration of the rotor of the motor is detected by the position sensor, and the excitation phase signal is added by the microcomputer so as to add the correction amount of the excitation phase to either the position command signal or the position detection signal. a stepping motor device including a position sensor according to claim 1, characterized in Rukoto is output. The microcomputer further includes a switching control unit for switching the step-out prevention switch, and the switching control unit allows a deviation amount between the position command signal and the position detection signal,
(A) If −90 ° ≦ deviation amount ≦ + 90 °, switch to the position command signal side,
The stepping motor device having a position sensor according to claim 2 , wherein when (b) -90 [deg.]> Deviation amount and +90 [deg.] <Deviation amount, switching to the position detection signal side is performed .

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