JPH09182476A - Controller for rotational speed of motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a controller for the rotational speed of a motor whose rotational accuracy is good and stable and which is miniaturized by a method wherein more rotational speed information signals of the motor are drawn out so as to control its rotation. SOLUTION: A means which generates a rotational speed information signal (a) according to the rotational speed of a motor 31 is installed. Comparators 34, 16 which create a first FG pulse and a second FG pulse on the basis of the level of the rotational speed information signal (a) is installed. A means by which cycles of the first and second FG pulses are compared with a predetermined reference cycle so as to create a first torque control command signal (c) and a second torque control signal (e) is installed. In a section in which the first FG pulse rises and in a section in which the second FG pulse rises, the first control command signal (c) is created by a multiplexer 19, and, in other sections, a torque control command signal (g) which outputs the second torque control command signal (e) is created by the multiplexer 19. Thereby, the rotational speed of the motor 31 is controlled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotation speed control device for rotating a motor at a constant speed, and a new rotation speed control device for controlling the rotation of the motor on the basis of two extracted torque control command signals. It is characterized in that a torque control command signal is generated to control the rotation speed of the motor.

[0002]

2. Description of the Related Art In recent years, motors have been able to obtain stable rotation with the improvement of machining accuracy, and further improvement in the rotational accuracy is also desired. A conventional motor rotation speed control device will be described below. FIG. 3 is a block diagram of a conventional rotation speed control device. In FIG. 3, 31 is a motor, 32 is an FG detection head which is attached to the motor and generates a rotation speed information signal (hereinafter referred to as FG) having a frequency corresponding to the rotation speed, and 33 is an FG signal generated in this FG detection head 32. An amplifier 34 for amplifying the FG pulse b compares the FG amplified signal a with the center voltage value (DC component voltage value) of the FG amplified signal.
Is a comparator 35 for outputting the speed of the reference FG pulse at a predetermined rotation speed of the motor 31 and a speed discrimination circuit for comparing the cycle of the FG pulse b detected by the FG detection head 32. The motor driver drives the motor 31 by the motor torque control command signal obtained as a result of the determination.

The operation of the motor rotation speed control device configured as described above will be described below. First, the motor driver 36 causes the motor 31 to generate a rotational torque in response to the torque control command signal c from the speed determination circuit 35. As a result, when the motor 31 starts to rotate, a sine wave whose cycle changes according to the rotation speed of the motor 31 produces a sine wave.
2 occurs. This signal is amplified, and the cycle of the FG pulse b waveform-shaped by the comparator 34 using the waveform center, which is the DC component value of the sine wave, as a threshold value, and the predetermined reference cycle at the rotation speed of the motor 31 are set. Speed comparison is performed by comparison.

That is, when the cycle of the FG pulse detected by the FG detection head 32 of the motor 31 is longer than the predetermined reference cycle of the motor, it is determined that the rotation of the motor 31 is slower than the preset speed. On the contrary, if it is short, it is determined that the rotation of the motor 31 is fast. The speed discriminating circuit 35, which discriminates the slow speed of the rotation of the motor 31, outputs a control signal corresponding to the error amount of this cycle to the motor driver 36 as a torque control command signal c. The torque control command signal c controls the motor driver 36 so as to decelerate when the rotation of the motor 31 is faster than a preset speed and accelerate it when the rotation is slow. Thus, 1 of the FG pulse b
At every cycle, the motor 31 is fed back to control the rotation so as to reach a preset rotation speed.

Next, the above operation will be described with reference to FIG. When the reference cycle at the preset speed of the motor 31 is t, the rotation of the motor 31 is slower than the reference cycle t and returns to the reference cycle t again in an extreme case.
It shows how the amplified signal a, the FG pulse b, and the torque control command signal c change.

Since one cycle of the rising edge i at the left end and the second rising edge j shown in the FG pulse b is equal to the reference cycle t, the voltage of the torque control command signal c is 0 (v). Assuming that the torque control amount per reference period t is V (v), the next j and k time is 2t and the rotation speed is halved. Therefore, the torque control command signal c is + V (v) control voltage. Become. Since the next cycle of k and l is 3t, the torque control command signal c further increases by + V (v) and becomes a control voltage of + 2V (v). Similarly, since the cycles between 1 to m, m to n, and n to o are t, 0.5t, and t, respectively, the torque control command signal c is 0 (v), -0.5V (v), and 0, respectively.
The control voltage is (v). This torque control command signal c
Is output at each rising timing (indicated by an arrow in the figure) of the FG pulse b, which is a speed detection point, according to an error from the reference period t.

[0007]

However, with the conventional structure as described above, it was not possible to obtain sufficient rotation accuracy in a video tape recorder or the like which requires a high degree of rotation accuracy. In order to improve the rotation accuracy, the number of FG pulses per one rotation of the motor is generated as much as possible to increase the detection timing of rotation information and increase the number of speed control per rotation. For that purpose, the number of poles of the magnet of the motor must be increased, which complicates the FG detection device, and the device itself becomes large. In particular, it is small as in a video camera equipped with the video tape recorder. In the equipment required to be improved, the number of FG pulses for obtaining necessary rotation information cannot be increased, and there is a problem that rotation information cannot be obtained for improving rotation accuracy.

[0008]

In order to solve this problem, in the motor rotation speed control device of the present invention, the levels of the sinusoidal rotation speed information signals having the frequencies corresponding to the rotation speed of the motor are different from each other. Create first and second FG pulses indicating a section equal to or greater than the first and second threshold values,
The respective sections of the first and second FG pulses are respectively compared with a predetermined reference section, and first and second torque control command signals having levels corresponding to the difference are created, and the first and second torque control command signals are generated. The first torque control command signal is extracted during the period after the first FG pulse is created until the second FG pulse is created, and the second torque control command signal is extracted in the other intervals. The rotation speed of the motor is controlled according to the extracted torque control command signal.

According to the present invention, it is possible to increase the number of poles of the motor magnet without increasing the size of the FG detection device.
Since more rotation speed information of the motor can be extracted from the detection head and the rotation speed of the motor can be closely controlled, it is possible to provide a stable rotation speed control device of the motor with high rotation accuracy.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is the first and second thresholds in which the levels of the sinusoidal rotational speed information signal having a frequency corresponding to the rotational speed of the motor are different from each other. 1st and 2nd FG showing the section that is equal to or greater than the value
A pulse is created, and each of the sections of the first and second FG pulses is compared with a predetermined reference section,
After creating the first and second torque control command signals having levels corresponding to the difference and creating the first FG pulse,
The period until the second FG pulse is generated is the first
And a second torque control command signal in the other sections, and the rotation speed of the motor is controlled according to the extracted torque control command signal. Therefore, precise speed control can be performed from the extracted speed information, and stable rotation of the motor with high rotation accuracy can be obtained.

According to a second aspect of the invention, means for generating a sinusoidal rotation speed information signal having a frequency corresponding to the rotation speed of the motor, and the first and the first rotation speed information signals having mutually different levels. Comparing the first and second FG pulse indicating a section equal to or larger than the threshold value of 2 with each of the sections of the first and second FG pulse and a predetermined reference section, respectively. , Means for generating first and second torque control command signals having levels corresponding to the difference, rising of the first FG pulse and second F
Means for extracting the first torque control command signal in the section up to the rise of the G pulse, and second torque control command signal in the other sections, and the means for extracting the torque control command signal Controlling the rotation speed of the motor, wherein the rotation speed of the motor is closely controlled by the torque control signal created by the extracted first and second torque control command signals. Therefore, stable rotation of the motor with high rotation accuracy can be obtained.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
1 to 2 will be described. The blocks having the same functions as those of the conventional configuration shown in FIG. FIG. 1 is a block diagram of a motor rotation speed control device according to an embodiment. The difference from the conventional example is that, in addition to the conventional comparator 34 and speed discriminating circuit 35, a second inverted output having a predetermined threshold value is provided.
Of the output pulse d of the second comparator 16, the second speed discriminating circuit 17 for discriminating the speed by the time from the rising pulse to the next rising pulse, and the two speed discriminating circuits 35, 17. It has a multiplexer 19 for switching the output and a timing generator 18 for taking the switching timing.

Next, the operation will be described with reference to FIG. 2. Assuming that the rotation of the motor 31 is rotating at the same rotation speed as in the conventional example, the FG waveform detected by the FG detection head 32 is amplified. When amplified by 33, its output waveform becomes the same output waveform a as the waveform a of FIG. 4 used in the description of the conventional example. Similarly, the comparator 34 and the speed discriminating circuit 35 perform exactly the same circuit operation as in the conventional example. Therefore, the output waveform of the comparator 34 is as shown in FIG. 4B, and the output waveform of the speed discriminating circuit 35 (torque control command signal ) Has a waveform like c. Further, the second comparator 16 newly added in the present invention sets a threshold value at a point deviated from the center threshold value of the comparator 34 by Δe (v), and the output voltage waveform of the second comparator 16 is The output waveform becomes an output voltage waveform as shown by d in FIG.

In the second speed discriminating circuit 17, the rising cycle of the pulse d (indicated by the arrow in FIG. 2) is compared with a predetermined rotation reference cycle t of the motor, and control is performed according to the error amount. The signal is output as an output waveform (torque control command signal) e of the second speed determination circuit 17. Assuming that the torque control amount per rotation reference period t is V (v), 1.4t is detected between the left-side rising edge p of the pulse d and the next rising edge q, so that the torque control command signal is 0. The output voltage is 0.4 V (v). The torque control command signal has an output voltage of 1.6 V (v) because 2.6 t is detected between q and the next rising r. Similarly, the time between r to s, s to t, and t to u is 2 respectively.
Since they are t, t, and 0.5t, the torque control command signals are output voltages of V (v), 0 (v), and -0.5V (v), respectively. The torque control command signal e created in this way has a positive voltage when the motor rotates slowly and acts to accelerate the motor, and a negative voltage when the motor rotates quickly, and decelerates the motor. work.

Next, in the output waveform of the comparator 34 (b in FIG. 4) and the output waveform of the second comparator 16 (d in FIG. 2), a pulse f that rises when b rises and falls when d rises. (Hereinafter referred to as switching timing pulse) is created by the timing generator 18, and this is input to the output switching terminal of the multiplexer 19. The multiplexer 19 time-divides the two inputs of the torque control command signal c of the speed discriminating circuit 35 and the torque control command signal e of the second speed discriminating circuit 17 with the switching timing pulse f, and switches them alternately. And outputs a torque control command signal g.

That is, the torque control command signal g outputs the waveform of the first torque control command signal c when the switching timing pulse f is at "H" level, and the waveform when the switching timing pulse f is at "L" level. The waveform of the second torque control command signal e is output.

More specifically, in the waveform of the torque control command signal g, since the section A indicated by the switching timing pulse f is at the "H" level, the voltage 0 (v) of the first torque control command signal c is first. Is output and the next section of B is "
Since it is at the L "level, the voltage 0.4v (v) of the second torque control command signal e is output. Since the next section C is at the" H "level, the first torque control is performed again. The voltage v (v) of the command signal c is output, and in the section D, the voltage of the second torque control command signal e is 1.6 in the same manner as above.
Output v (v). Similarly, in the sections of E, G, I and K, which are "H" level sections, the voltages 2v (v), 0 (v), -0.5 of the first torque control command signal c are obtained.
v (v) and 0 (v) are output, and the voltage of the second torque control command signal e is v (v) and 0 (v) in the F, H, and J sections, which are "L" level sections, respectively. , -0.5 (v) is output.

That is, the first torque control command signal c is output during the period from the generation of the first FG pulse b to the generation of the second FG pulse d, and the second interval is the second torque control command signal c. Of the torque control command signal e, and the rotation speed of the motor 31 is controlled according to the extracted torque control command signal g.

In this way, the torque control command signal g created by alternately switching the first and second torque control command signals c and e by the switching timing pulse f is input to the motor driver 36 to control the motor 31. To do. As a result, the motor 31 is controlled to increase the rotation torque when the rotation is slow and to decrease the rotation torque when the rotation is fast. As described above, according to the embodiment of the present invention, more rotation speed information can be extracted from the same FG signal, and the rotation control of the motor 31 can be performed more closely.

In the embodiment of the present invention, the comparator 3
The waveform center, which is the DC component value of the waveform a obtained by amplifying the sine wave of the motor 31 in which the rotation frequency of the FG detection head 32 changes at the detection point of the FG pulse of 4, is set as the threshold value. The detection points may be shifted by setting to the level of. Also, amplified FG
The rotational frequency shift is detected by differentiating the pulse waveform a, and based on this waveform, the motor 31
Since the rotation speed of the motor 31 can be controlled, stable and accurate control of the rotation speed of the motor 31 can be performed as in the above-described embodiment.

[0021]

As described above, according to the present invention, since the precise rotation speed control can be performed from one rotation speed information signal,
It is possible to realize a stable and miniaturized motor rotation speed control device with good rotation accuracy.

[Brief description of the drawings]

FIG. 1 is a block diagram of a motor rotation speed control device according to an embodiment of the present invention.

FIG. 2 is a waveform diagram of each part of the block diagram of the device.

FIG. 3 is a block diagram of a conventional motor rotation speed control device.

FIG. 4 is a waveform diagram of each part of the block diagram.

[Explanation of symbols]

 31 motor 32 FG detection head 33 amplifier 34 comparator 35 speed determination circuit 36 motor driver 16 comparator 17 speed determination circuit 18 timing generator 19 multiplexer a FG amplification signal b FG pulse c torque control command signal d FG pulse e torque control command signal f Switching timing pulse g Torque control command signal

Claims (2)

[Claims] 1. A first FG and a second FG indicating sections in which the levels of sinusoidal rotational speed information signals having a frequency corresponding to the rotational speed of a motor are equal to or higher than first and second thresholds, which are different from each other. A pulse is created, and each of the sections of the first and second FG pulses is compared with a predetermined reference section, and the first and second torque control command signals having levels according to the difference are compared. The period from the creation of the first FG pulse to the creation of the second FG pulse is
The first torque control command signal is set to the second section for other sections.
Of each of the torque control command signals described above, and controlling the rotation speed of the motor according to the extracted torque control command signal. 2. Means for generating a sinusoidal rotation speed information signal having a frequency corresponding to the rotation speed of the motor, and first and second rotation speed information signals having mutually different levels.
Comparing the first and second FG pulse indicating a section equal to or more than the threshold value of, and each section of the first and second FG pulse with a predetermined reference section, respectively, Means for creating first and second torque control command signals having levels according to the difference, and the section from the rising of the first FG pulse to the rising of the second FG pulse is the first torque control. Rotation speed control of the motor, which comprises means for extracting the command signal and second torque control command signal in other sections, and means for controlling the rotation speed of the motor in accordance with the extracted torque control command signal. apparatus.