JPS62290399A - Extractor of excitation change-over timing signal for stepping motor - Google Patents

Abstract

PURPOSE:To expand variable limits and shorten the processing time from the rotor position detection to the excitation change-over, by making the excitation change-over timing continuously variable. CONSTITUTION:From an encoder 2 are obtained rotor position signals of phase A of sinusoidal wave corresponding to the rotor position of a stepping motor 1 and of phase B deviated from the phase A by 90 deg. in phase. These rotor position signals are amplified by non-reversing amplifiers 3 and 5, and by reversing amplifiers 4 and 6, signals of phase A bar and phase B bar are made out. These total four position detecting signals are regulated in level by variable resistance 7, 8 and 10 and added through buffers 11, 12, 13 and 14, so that the position signal of phase C is obtained. Setting the zero cross point of this addition signal as the exciting change-over point, the stepping motor rotates continuously.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to an excitation switching timing signal extraction device for a stepping motor that obtains an excitation switching timing signal based on a rotor position detection signal.

(Prior technology) It has an optical or magnetic rotary encoder,
There is a stepping motor whose excitation timing is adjusted based on a rotor position detection signal from this encoder. There are various types of stepping motors as described below.

(a) The rotor position is detected by the sine wave output level of the encoder, and the excitation switching timing signal is generated by comparing the sine wave output level with a reference level, and the excitation switching timing is determined by switching the comparison reference level. The one that adjusted the.

(b) The rotor position is detected by counting the number of output pulses from the encoder, and the excitation switching timing is adjusted based on this.

(C) The rotor position is detected by a digital pattern of several bits of an encoder, and the excitation switching timing is adjusted based on this.

(Problems to be Solved by the Invention) According to the method (a) above, since the peak point of the encoder output cannot be detected, the adjustment of the excitation switching timing becomes discontinuous. According to the methods (b) and (c) above, the excitation switching timing is varied digitally and is not continuous, and the number of divisions to make the excitation switching timing variable is variable. Due to limitations, it is not possible to widen the variable range.

The present invention has been made in order to solve such conventional problems, and makes it possible to continuously vary the excitation switching timing, widen the variable range, and furthermore, It is an object of the present invention to provide an extraction device for an excitation switching timing signal for a stepping motor that can shorten the processing time from position detection to excitation switching.

(Means for Solving the Problems) The present invention provides 9
Four position detection signals are obtained by two position signals with a phase difference of 0 degree and a signal with an opposite phase of these two position signals, and each of at least two position detection signals among these four position detection signals is The present invention is characterized in that the excitation switching timing signal is extracted by changing the ratio and adding it.

(Function) By the rotation of the stepping motor, a total of four position detection signals are obtained by two position signals having a phase difference of 90 degrees from each other and a signal with the opposite phase of these two position signals. The stepping motor rotates continuously by adding at least two of these four position detection signals and setting, for example, a zero-crossing point of the added signal as an excitation switching point. If the ratio of the at least two signals to be added is changed, the zero-crossing point of the added signals moves, and the excitation switching point moves.

(Example) Hereinafter, an example of an extraction device for an excitation switching timing signal for a stepping motor according to the present invention will be described with reference to the drawings.

In FIG. 1, an optical or magnetic encoder 2 is directly connected to the rotational output shaft of a stepping motor 1.
As the stepping motor 1 rotates, the encoder 2 provides a sine wave A phase corresponding to the loaf position of the stepping motor 1 and a B phase rotor position signal that is 90 degrees out of phase with the A phase. . The encoder 2 may be externally attached to the stepping motor l,
The A-phase and B-phase rotor position signals, which may be built-in, are amplified to the required level by the non-inverting amplifier 3.5, and the A-phase and B-phase rotor position signals are amplified to the required level by the inverting amplifier 4.6, respectively. A signal is being generated. These four position detection signals in total are level-adjusted by variable resistors 7.8.9.1o, and then added via buffers 11.12.13.14 to obtain a C-phase position signal. It has become. This C-phase position signal is input to the comparator 15, and is compared at the center level of the input signal, that is, at the zero cross point. The output of the comparator 15 is an edge detection circuit 1 having a delay circuit and an exclusive OR circuit.
6 and generates narrow pulses at the rising edge and falling edge of the output of the comparator 15.

Reference numeral 17 is a start pulse generation circuit, which generates 1 at startup.
It is designed to generate pulses. Pulses from the start pulse generation circuit 17 and the edge detection circuit 16 are input to the excitation controller 19 via an OR circuit 18. The excitation controller 19 advances the excitation state of the stepping motor I one by one each time one pulse is input. This embodiment is an example of four-phase excitation, and the excitation controller 19 sequentially switches four outputs each time one pulse is input, and the four buffer amplifiers 20, 21, 22, and 23 each output the excitation controller 19. The power is amplified and supplied to each phase of the stepping motor 1.

Next, the operation of the above embodiment will be explained with reference to FIGS. 2 to 5.

Now, when driving a 4-phase stomping motor with 1-phase excitation, the relationship between the positions at which each of the excitation phases φ1, φ2, φ3, and φ4 stops due to excitation and the two outputs of encoder 2 is shown in Figure 3. so that the relationship is as shown in
That is, the stop positions ■■■■ are set so as to coincide with the zero-crossing points of the A-phase output of the encoder 2, respectively. The rotation direction is clockwise CW.

In Figure 2, when the rotor rotates at position 2, the excitation is switched from φ1 to φ2, and when the rotor rotates to position 2, the excitation is switched from φ2 to φ3, and so on. By switching the excitation while detecting this, smooth rotation is possible without any adjustment or disturbance. However, high-speed rotation is not possible in this state.

Here, for example, when the excitation is switched from φ1 to φ2 and the rotor is moving from position ■ to position ■, it is detected that the rotor has reached position 2', for example, and the next excitation phase φ is detected.
If the excitation can be switched to 3, it will be possible to stably rotate at high speed. According to the embodiment shown in FIG. 1, the excitation can be switched to the next excitation phase while the rotor is rotating toward a predetermined stop position as described above, and this allows stable high-speed operation. You can get rotation.

It is now assumed that φl of the stamping motor 1 is excited and the rotor is stopped at position ■. The direction of rotation is clockwise discharge. Adjust variable resistors 7 to 10 to connect phase A and B.
The phase is set to zero, the A phase and the B phase are set to a one-to-one level, and a C-phase signal is created by adding these together. It is assumed that the comparator level of the comparator 15 is set at the zero-crossing point of the input signal. When one pulse is input from the start pulse generation circuit 17 to the excitation controller 19, the excitation is switched from φ1 to φ2, and the rotor starts rotating from position ① toward position ②. When the rotor passes position b while rotating from position ■ to position ■,
The output of the comparator 15 is inverted when the C-phase signal passes the zero cross point, that is, the comparison level of the comparator 15, and one pulse is output from the edge detection circuit 16, and the excitation is switched from φ2 to φ3, and the rotor passes through position ■ and continues rotating toward position ■.

When the rotor passes the position C during the rotation from ■ to ■, the C phase signal passes through the comparator level of the comparator 15 again, so one pulse is output from the edge detection circuit 16, and the excitation changes from φ3. The rotation is switched to ψ4, and the rotor passes through ■ and continues rotating toward ■. Thereafter, the same operation is repeated, and the rotor continuously rotates.

Here, since the C-phase signal is the sum of the A-phase and B-phase signals, by changing the ratio of the A-phase and B-phase signals,
The zero-crossing point of the phase signal can be moved within a range of 45 electrical degrees. For example, the point b can be moved between the positions ■ and 2 degrees, and in this way, the extraction position of the excitation switching timing signal of the stamping motor can be made continuously variable.

Furthermore, by sequentially changing the variable resistors 7, 8, 9 and IO, the excitation switching point can be sequentially moved. Figure 4 shows the position detection signal and φ1 during clockwise CW rotation.
This shows the positional relationship with switching point b from φ3 to φ3, and shows the movement of switching point b when the stop position due to excitation of φ3 is set as a reference (0°). As shown in Fig. 4, if each variable resistor 7, 8, 9, and lO are selectively and sequentially changed, the excitation switching point b from φ2 to φ3 is 2°-
It can be moved sequentially like (f)-■-■. In other words, in order to move the switching point b with reference to the stop position due to φ3 excitation, it is sufficient to set the levels of each signal based on FIG. 4 and add them. For example, in order to move the switching point b in the region shown in FIG. 2, it is sufficient to set the levels of the A phase and B phase and add them.

Moreover, when rotating in the counterclockwise direction cch, the switching order of each excitation phase may be reversed. The positional relationship between the position detection signal and the excitation switching point +-b in this case is shown in FIG. In this case as well, in order to move the switching point, the A phase,
Select each phase, B phase, and π phase signals, set their levels, and add them.

Note that the other switching points c, d, and a also move at the same time as the above-mentioned switch moves.

FIG. 6 shows the relationship between the advance angle θ of excitation timing and the pulse rate. As is clear from FIG. 6, it can be seen that the rotational speed can be controlled by adjusting the advance angle θ.

Next, the embodiment shown in FIG. 7 will be described. In this embodiment, as shown in FIG. 8, each of the four excitation phases φl, φ
2. Stop position by excitation of φ3 and φ4 respectively
In the case of (2), these stop positions (■■■■) are made to coincide with the zero-crossing points of the human phase and B phase detection signals as shown in FIG. In this case, as can be seen by comparing FIG. 3 and FIG. 9, the period of the position detection signal per predetermined rotation becomes 1/2 of that in the first embodiment. Therefore, two sets of devices were installed to change the ratios of the A-phase, A-phase, B-phase, and π-phase rotational position detection signals obtained by the output of the encoder 2 and add them.
A C1 phase signal and a C2 phase signal having a phase difference of degrees are obtained.

Specifically, the A-phase, input phase, B-phase, and π-phase signals are added together via a group of variable resistors 71.81.91.101 and a group of buffers 111.121.131 and 141, and the C
In order to obtain one phase signal, another group of variable resistors 72, 82, 92, 102 and another group of buffers 11
2.122.132.142 and the above C1
A C2 phase signal having a phase difference of 90 degrees with respect to the C2 phase signal is obtained. These C1 phase and 02 phase signals are input to the excitation controller 19 via the edge detection circuits 161 and 162, respectively, and the OR circuit 18. The other circuit configurations are the same as in the first embodiment.

In the embodiment shown in Fig. 7, if the C1 phase and C2 phase are obtained by adding each signal as shown in Fig. 1O (a) and (b), the zero cross point of the C1 phase will be the excitation from φ1 to φ2. This becomes the switching point and the excitation switching point from φ3 to φ4, and the zero cross point of the C2 phase becomes the excitation switching point from φ2 to φ3 and the excitation switching point from φ4 to φl.

In this way, two sets of detection signals with a phase difference of 90 degrees are required in order to match the rotor stop position with the zero-crossing points of phase A and phase B and to obtain four excitation switching signals. In the embodiment shown in FIG. 7, the 01 phase and 02 phase with a phase difference of 90 degrees
In order to obtain two phase signals and to shift the excitation switching timing based on these two signals, a total of eight variable resistors in two groups are used.

Contrary to the case of the embodiment shown in FIG. 7, one phase of the position detection signal, for example, as shown in FIG. The stop position of the rotor may be made to coincide with the point. In this case, the period of the position detection signal is twice that of case 3 of the first embodiment as shown in FIG. Therefore, for example, in the embodiment shown in FIG. 11, the edge detection circuit 16 detects only the rising edge in clockwise rotation, and the edge detection circuit 16 detects only the rising edge in counterclockwise rotation. (By switching to detect only the edge 11, it is possible to adjust the excitation switching timing in the same manner as described above.

The present invention is applicable not only to a four-phase stepping motor, but also to a four-phase stepping motor.
Applicable to stepping motors with any number of phase configurations. For example, in the case of a three-phase or five-phase configuration, the stop position may be aligned with the zero cross point of one of the rising and falling edges of the detection signal of one phase, as in the case of FIG. Moreover, it is also possible to control excitation switching timing.

Further, in the case of two-phase excitation, it is possible to realize the same if the relationship between the rotor stop position and the detected output corresponds to that of each of the embodiments described above.

The excitation switching timing does not necessarily need to be changed continuously; for example, as shown in FIG. 12, the excitation switching timing may be changed stepwise using a changeover switch 30 instead of a variable resistor.

The same effect can be obtained even if the stop position of the rotor does not necessarily correspond to the zero-crossing point of the position detection signal.

(Effects of the Invention) According to the present invention, four position detection signals are obtained by two position signals having a phase difference of 90 degrees and a reverse phase signal of these position signals, and among these four position detection signals, By changing the ratio of at least two signals and adding them, the timing can be varied continuously over a wide range. Furthermore, since the excitation switching timing signal is created by combining the position detection signals, there is little time loss from position detection to excitation switching.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of an excitation switching timing signal extraction device for a stepping motor according to the present invention, and FIG.
The figure is an explanatory diagram of the relationship between each excitation phase and the rotor stop position in the above embodiment, Figure 3 is a waveform diagram showing the relationship between the position detection signal and the rotor stop position in the above embodiment, and Figure 4 is the excitation timing signal Figure 5 is an explanatory diagram showing the addition ratio of each phase signal of the position detection signal for adjusting the position detection signal, Figure 5 is an explanatory diagram showing the ratio of each phase signal during reverse rotation, and Figure 6 is the advance angle of excitation timing and stepping Diagram showing the relationship with the motor rotation speed, No. 7
9 is a circuit diagram showing another embodiment of the excitation switching timing signal extraction device for a stepping motor according to the present invention; FIG. 8 is an explanatory diagram of the relationship between each excitation phase and the rotor stop position in the same embodiment; The figure is a waveform diagram showing the relationship between the position detection signal and the rotor stop position in the above embodiment, and Figure 10 shows the addition ratio of each phase signal of the position detection signal for adjusting the excitation timing signal in the above another embodiment. FIG. 11 is a waveform diagram showing the relationship between the position detection signal and the rotor stop position according to yet another embodiment of the present invention, and FIG. 12 is a circuit diagram showing still another modification of the present invention. . U 7 Mouth shape 4 U O mouth 6 Kuni Shin, soup angle θ (waste)

Claims (1)

[Claims] Four position detection signals are obtained by two position signals with a phase difference of 90 degrees obtained by the rotation of the stepping motor and a signal with an opposite phase of these two position signals, and at least two of these four position detection signals are An apparatus for extracting an excitation switching timing signal for a stepping motor, which extracts an excitation switching timing signal by changing and adding the ratios of two position detection signals.