JPS58165697A - Drive device using pulse motor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] The present invention uses a pulse motor as a driving source to move objects (loads).
This relates to a drive device for a moving object that moves the object, and after driving the moving object to a target position using a pulse motor,
The structure is configured to reduce residual vibration when stopped, and to achieve both high-speed drive and high resolution.

The present invention is a drive device capable of achieving both high-speed drive and high resolution of a pulse motor.
I made one proposal as No. 7.

When a pulse motor is desired to be fed at high speed, it is normally driven by a chopper constant current power supply with a fast current rise.

As described in Japanese Patent Application No. 56-97877, when driving a load to a target position by gradually increasing or decreasing the phase current of a pulse motor, the motor torque will decrease because the current of the chopper constant current power source is a pulsating current. This causes pulsation in the motor, which causes the rotor of the motor to vibrate, deteriorating the stability when stopped.

If you increase the chopper frequency of the chopper constant current power supply, that is, if you increase the torque fluctuation frequency, the flywheel effect of the motor rotor and load will increase and stability will improve, but there is a limit to increasing the chopper frequency. The higher the resolution, the more difficult it was to obtain stability.

In view of this, an object of the present invention is to provide a drive device that eliminates vibration of the motor rotor when stopped, improves stopping stability, and can easily achieve both high-speed drive and high resolution.

Referring to FIG. 1, an embodiment in which the present invention is applied in a closed loop system will be described. 1 is a pulse motor, A, B
, A, and B, and drives the screw shaft 2.

3 is fixed to the table 4 with a nut screwed onto the screw shaft 2. 5 is a linear scale fixed to the table 4 and has an optical scale or a magnetic scale; 6 is a fixed head for reading the scale of the scale 6; The signals generated sequentially as the table 4 moves from the head 6 are detected by the counter 8.
The counter 8 inputs the position signal 9 of the table 4 to B
It is outputted to the control circuit 1o using a CD code or the like. Tr11
Tr21Tr31Tr4 are each A.

This is a transistor for driving the B, A, and B coils.

11 is an excitation switching circuit for 2-phase excitation of the pulse motor 1, and a pulse output 1 in the CW direction from the control circuit 1o.
2 or CCW direction pulse output 13, the transistor "rl 1Tr" is activated at a predetermined timing.
2+” r31” Base voltage of r4 is 0N-OFFL
, drives the pulse motor 1. Further, the excitation switching circuit 11 outputs an excitation position signal 14 indicating which phase is excited to the control circuit 1o. A variable bias circuit 16 applies a continuously changing bias signal to the base of a predetermined transistor by a variable bias application signal 16 from the control circuit 1o. Therefore, the base voltage of the transistor becomes a composite voltage in which the output voltages to the bases of the excitation switching circuit 11 and the variable bias circuit 15 are superimposed. 17 is a monitor signal for the base voltage of each transistor. 18 is for sending the table 4 to the target position.
This is a target position command signal. Although not described in detail, the control circuit 10 has a known acceleration/deceleration function for driving the pulse motor 1 at high speed. 19 is a known chopper constant current power supply (hereinafter abbreviated as chopper power supply); 2o is a known DC power supply having a better waveform factor than the chopper power supply 19, that is, having a ripple removal function and close to pure DC. 2 and 2
2 is a switching element such as a thyristor or a relay, which is selectively turned on and off by signals 25 and 26 from the power supply switching circuit.

Reference numeral 27 is a switching command signal for controlling the power supply switching circuit 23.

When the target position command signal 18 is input, the control circuit 1o compares it with the current position signal 9 of the table 4 and determines whether the pulse motor 1
The rotation direction, the number of steps required when driving with two-phase excitation, the number of acceleration/deceleration pulses, acceleration/deceleration timing, control switching setting positions, etc. are set as shown in FIGS. When the setting is completed, the control circuit 10 uses the switching command 27 to turn the power supply switching circuit 23 so that the switching element 21 is turned on and the switching element 22 is turned off.
A chopper power source 19 for high-speed driving is connected to the pulse motor 1.

Next, the control circuit 10 outputs a pulse 12 to the excitation switching circuit 11.
Alternatively, the pulse motor 1 is driven by two-phase excitation, and the table 4 is sent toward the target position.

Next, the operation of each part after the table 4 reaches the vicinity of the control switching setting position shown in FIG. 6 will be explained with reference to FIG. 2.3.4.

FIG. 2 shows changes in the base voltage of each transistor, the broken line shows the voltage applied to each transistor by the excitation switching circuit 11, and the dashed line shows the voltage applied to each transistor by the variable bias circuit 15. Therefore, the voltage actually applied to the base of each transistor is a composite voltage of the respective voltages shown by the solid line. FIG. 3 shows changes in the current flowing through each phase. FIG. 4 shows the displacement of the rotor of the pulse motor, and AB, BA, AB, and BA indicate the equilibrium positions of the rotor when the respective two phases are excited.

For example, assume that the AB2 phase is excited before the control switching setting position, then switch to the BA phase at time t1, and then at time t
2, when the table 4 reaches the control switching setting position, the control circuit 1o determines this based on the position signal 9, and outputs a pulse 1.
2 or 13 is stopped, and the BA phase is kept in the excited state.

Further, when the table 4 reaches the control switching setting position, the control circuit 1o switches the switching element 21 from ON to OFF, 22
The power supply switching circuit 23 switches from OFF to ON.
At time t2', the pulse motor 1 is excited by pure direct current with a good waveform ratio from the pulsating current generated by the chopper, as shown in FIG.
After the preset time T has elapsed, that is, the time t
At step 3, the control circuit 10 determines which phase is currently excited based on the excitation position signal 14, and controls the variable bias circuit 15.
When the base voltage of Tr2 is gradually lowered as shown in FIG. 4 by controlling the
It moves gradually from the BA position toward an intermediate position between the BA position and the AB position, without allowing it to naturally attenuate. When the B-phase current becomes zero at time t4, that is, the base voltage of r2 becomes zero, the control circuit 1 determines this based on the base voltage monitor signal 17, and controls the excitation switching circuit 11 to switch the excitation from the B-phase. B
At the same time as switching to the phase, the variable bias circuit 16 is controlled to gradually increase the base voltage of "r4. As a result, the rotor continues to gradually move toward the AB position. At time T6, the voltage of "r4 '1) is increased. When the base eaves power rises to the maximum, the base voltage monitor signal 1
7, the control circuit 1o determines this, controls the variable bias circuit to gradually lower the A-phase current, and moves the rotor toward the target position.

When the O rotor reaches the target at time t6, the control circuit 1o determines this based on the position signal 9, and controls the variable bias circuit 16 using a known servo method (not described in detail) to stop the A-phase current change. The rotor is stopped at the target position, and the positioning of the table 4 is completed.

At this time, for example, in a state of being excited by a chopper current, from t3 to t
If the operations up to 6 are performed, the phase currents of the two phases are the same at times t3 and t5, and at t4, one phase is excited, so no vibration occurs, but when the two phase currents are different, the motor The rotor 1 vibrates due to the pulsation of the chopper current, and the rotor displacement becomes as shown in Figure 7.
High-resolution positioning cannot be expected.

According to the above method, it is possible to easily achieve both high-speed drive using a chopper constant current in which the current rises and falls quickly, and theoretically infinitesimal resolution due to DC excitation positioning operation in which the motor rotor does not cause imaging. I can do it.

Since the object of the present invention is achieved by exciting the pulse motor with a direct current having a good waveform ratio during the final positioning operation, the configuration shown in FIG. 8 may be adopted. 19 is a chopper power supply, 30 is a smoothing circuit using, for example, LC, and 28 is a switching element similar to 21 and 22, which is selectively turned ON and OFF by a signal 29 from the power supply switching circuit 23.

When sending at high speed by two-phase excitation, switching element 28
<)NL, that is, it is equivalent to connecting the chopper power supply 19 directly to the pulse motor 1 without going through the smoothing circuit 3o, and it is possible to obtain a current with a fast rise Table 4
When reaches the control switching position, the switching element 28 is turned OFF.
When F is applied, the chopper current is smoothed through the smoothing circuit 3o, becomes a direct current with a good waveform rate, and excites the pulse motor 1. If the current is passed through a smoothing circuit, the rise of the current will be slow due to the large time constant of the smoothing circuit, but there is no problem since there is no need to drive at high speed.

Therefore, in this configuration, the power supply and switching elements are 1
It's inexpensive because you only need one at a time.

In addition, the distance between the control switching position and the target position, the time T, the time between t4 and 13, and the time between t4 and 15 in Fig. 4 must be selected so that residual vibration of the rotor does not interfere with positioning. Bye. Therefore, the time between t4 and 13 and the time between t4 and 16 may be lengthened by shortening T or setting it to zero. Further, the method of gradually increasing and decreasing the current of the phase drive transistor is not limited to the method of this embodiment. Although the motor has been described as a four-phase rotary type motor, it may be of a linear type even if the number of phases changes. Moreover, although the load position detection has been described as a linear type, a rotary type may also be used. Further, the excitation switching circuit is not limited to the unipolar two-phase drive, but may be one-two phase drive, bipolar drive, or other types. Also, the base supply voltage of a variable bias circuit is not limited to one that varies linearly, but may vary stepwise or gradually according to a sine wave or other function, although the resolution may decrease depending on the purpose. It may be.

In the embodiment described above, a closed loop method using a linear scale has been described, but if the following method is used, the position accuracy will be lowered, but the open loop method can achieve both high speed drive and high resolution.

For example, if the required operating distance of the load is S, and the operating distance per step by the excitation switching circuit is P, the required number of steps n is S/P. The integer part of n is n1 the decimal part is n
2, the nth, A-th step is the control switching setting position,
The nl A step is driven by the excitation switching circuit using the chopper power supply, and the n 2 + A is driven by gradually increasing and decreasing the phase current with an electric discharge with a good waveform ratio, and the final fractional distance S P n
, stops changing the phase current when it reaches a preset phase current ratio corresponding to the fractional distance, the load stops at the target position. Whether the load has reached the control switching position may be determined by counting the number of pulses. However, A=0.1, 2.3...
! 1
' The present invention has a means for detecting the position of the load, and a pulse motor that switches each phase current from 0N to OFF until the load reaches a predetermined position near the target position, causing the phase current to rise rapidly and then fall to a high level. a first drive means that generates torque to drive the load at high speed; and a second drive means that smoothly drives the load to the target position by gradually increasing or decreasing the phase current of the pulse motor after the load reaches the predetermined position. a driving means, a power source for driving the load by at least the second driving means, the power source having a better waveform factor than the power source for driving the load by the first driving means, and selectively a power source for driving the load by the first driving means; By configuring it with a power supply switching circuit connected to a power supply pulse motor, it is possible to easily achieve both high-speed drive and high resolution due to improved stopping stability.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of one embodiment of the drive device of the present invention, FIG. 2 is a diagram showing changes in the pace voltage of the transistor in the configuration of FIG. 1, and FIG. 3 is a diagram of each phase in the configuration of FIG. 1. Figure 4 shows the displacement of the rotor of the pulse motor in the vicinity of the target position in the configuration shown in Figure 1. Figure 5 shows the speed diagram of the pulse motor from start to stop. Figure 6 shows the change in current. is a travel distance diagram of a pulse motor from start to stop, FIG. 7 is a diagram showing changes in the vicinity of the target position of the pulse motor rotor when the pulse motor excitation power source is only a chopper power source, and FIG. FIG. 7 is a schematic configuration diagram of main parts of another embodiment. 1---0-pulse motor, 2---screw shaft,
3. . ...Natsuto, 4...Table, 6.Fist...
...Scale, 6...Fixed head, 8...
IIe counter, 1°... Control circuit, 11...
...Excitation switching circuit, 16...Variable bias circuit, 19...Chopper constant current power supply, 2o...
...DC power supply with good waveform ratio, 21.22.28...
...1. Switching element, 23... Power supply switching circuit, 3o... Smoothing circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
Figure 13 Figure 4 Cause Figure 5 Figure $7 Procedural Amendment 1 Display of the case 1988 Patent Application Publication Department No. 7560 2 Name of the invention Drive device using a pulse motor 3 Relationship with the person who makes corrections Special ・Application for permission Colonel Address: 1006 Oaza Kadoma, Kadoma City, Osaka Name (582) Matsushita Electric Industrial Co., Ltd.
Toshihiko Yamashita 4 Agent Address 6, Matsushita Electric Industrial Co., Ltd., 1006 Oaza Kadoma, Kadoma City, Osaka 571 Contents of Amendment (1) The scope of claims column of the specification will be corrected as shown in the attached sheet. . (2) On page 3, lines 11-12 of the specification letter, ``The flywheel effect has become larger'' has been corrected to ``The flywheel effect and the current smoothing effect due to the inductance of the coil have become larger.'' (3) On page 11, line 14, correct the words ``or by other methods'' and ``or by other methods such as double 1-2 phase.'' (4) "It may be something" on page 11, line 19.
Next, ``In other words, it is sufficient to drive to a predetermined position near the target position by a driving means with a stepwise pitch, and to drive from the said position to the target position by a driving means with a small stepwise pitch.'' .”. (6) "Each phase current 0N-OFF' on page 12, line 20 of the same
"switch" should be corrected to "switch each phase current in steps". (6) In the second line of page 13, "a first driving means that drives at high speed," is corrected to "a first driving means that drives at high speed, that is, a step-pitch dog." (7) "The 24th driving means to drive" in the 5th line of page 13 is driven by 1, that is, the 24th driving means with a small step pitch is
and the means of driving it.'' 2. Scope of Claims (1) A pulse motor that drives a load to a target position, a detection means that detects the drive position of the load, and each of the pulse motors until the load reaches a predetermined position near the target position. phase! The first pulse motor was replaced with Li Goji Nisho.
a first driving means that drives at a stepwise pitch of 4, and a second drive means that gradually increases/decreases the current of the required phase of the pulse motor after reaching the predetermined position to increase the current of the required phase of the pulse motor from -10 stepwise. a second driving means that drives the pulse motor to a target position at pitch; a first power source that supplies current to the pulse motor; and a second power source that supplies the pulse motor with a current that has a better waveform ratio than the first power source. and a power supply switching circuit that selectively connects the first and second power supplies to the pulse motor, and at least when the second drive means drives the pulse motor, the second power supply connects the pulse motor to the pulse motor. A drive device using a pulse motor that supplies current. (2) A drive device using a pulse motor according to claim 1, wherein the first power source is a DC power source having a ripple removal function. (3) The first power supply is configured by a chopper constant current power supply,
Claim 1, characterized in that the second power supply is constituted by the chopper constant current power supply and a smoothing circuit, and the power supply switching circuit is constituted by a switching element connected in parallel with the smoothing circuit. A drive device using the pulse motor described in .

Claims (2)

[Claims] (1) A pulse motor that drives a load to a target position, a detection means that detects the driving position of the load, and a current of each phase of the pulse motor that is turned OFF until the load reaches a predetermined position near the target position. a first driving means for driving the pulse motor by switching; a second driving means for driving the pulse motor to the target position by gradually increasing the current of a required phase of the pulse motor after reaching the predetermined position; a first power source that supplies current to the pulse motor; a second power source that supplies current to the pulse motor with a better waveform factor than the first power source; and a second power source that selectively connects the first and second power sources to the pulse motor. A drive device using a pulse motor, comprising a power supply switching circuit connected to the pulse motor, and supplying current to the pulse motor from the second power supply at least when the pulse motor is driven by the second drive means. . (2) A drive device using a pulse motor according to claim 1, wherein the first power source is a DC power source having a ripple removal function. (3) The first power source is configured by a chopper constant current power source, the second power source is configured by the chopper constant current power source and a smoothing circuit, and the power source switching circuit is configured by a switching element connected in parallel with the smoothing circuit. A drive device using a pulse motor according to claim 1, characterized in that the drive device is configured as follows.