JPH0223081A - Speed controller - Google Patents

Abstract

PURPOSE:To obtain an error output which is not affected by the influence of the deviation of the period of a rotation signal by detecting the deviation of the period of the signal after the difference of deviated amounts of the value of the period of a continuous rotary signal becomes substantially constant, and storing it as reference value correction data in a memory. CONSTITUTION:A channel selector 3a updates an address signal of a memory 3c with a rotary signal obtained by waveform shaping an alternating voltage signal induced in the stator winding of a motor 1. A period detector 3d measures the period of the rotary signal, and stores it on the basis of the address signal in the memory 3c. A calculator 3b outputs an error signal between period data and reference speed data. If the deviation of the ratio of the period data of the address designated by the address signal is eliminated, the deviation of the period data of front and rear addresses is obtained, and the reference value is corrected in the address.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a speed control device that controls the rotational speed of a rotating body to a desired value.

Conventional technology Conventionally, as a method of controlling the rotational speed of a rotating body to a desired value, the alternating voltage induced in the stator winding of the rotating body is waveformed into a rectangular wave without connecting a speed all-electric machine to the rotating body. A method using a shaped signal (FC signal) (for example, "brushless DC motor drive system I that omit position detection
National Technical Report p6
14 Vol, 33 No. 5 OCT, 1911
7), the frequency or repetition of the FC signal 171
Speed control is performed using only the period as speed information, and section 1
It is possible to relatively stably control the speed of a rotating body with a simple configuration (for example, as shown in Japanese Patent Publication No. 18434/1983).By the way, this frequency or period detection method is applicable to stator windings. The alternating voltage induced in the rectangular wave signal is sufficiently amplified until it becomes a rectangular wave signal, and a predetermined edge of the rectangular wave signal is regarded as having speed information, and an error output signal is generated.

For example, in a typical period detection method, clock pulses are counted in the period from the leading edge (C front edge) of the amplified alternating voltage rectangular wave signal to the next leading edge. Then, based on this count value, a pulse width modulation signal (used when using a chopper type drive method) is generated, or the count value is converted into an analog voltage. I am getting the error output.

Therefore, in order to achieve more accurate control, it is necessary to make the alternating voltage induced in the stator windings the same at a constant rotation speed and to make the period of the rectangular wave signal more accurate.

Problems to be Solved by the Invention However, in the above-mentioned configuration, for example, a rotating body consisting of 12 poles (6 pole pairs) in the rotor and 9 coils in the stator can be used in three different ways. (■ When rotating using a half-wave driving/assisting system, the period of the rectangular wave signal obtained by amplifying the alternating voltage induced in the stator winding is Due to variations in the mounting accuracy of the child and stator, cycles that are longer and shorter than the normal cycle appear alternately in each cycle, resulting in a disturbance in the control system with a frequency that is half the frequency of the square wave signal. There was a problem in that the control characteristics deteriorated, especially in video tape recorders (VTRs).
) Schilling motors, which require high-precision rotation, have a problem with the frequency of disturbances, even though they are within the control system's inertia region.

In addition, since almost no adjustment is made during production, it is difficult to accurately control the period of the FG signal for all units.

In view of the above-mentioned problems, the present invention provides a method for determining whether the period of the rectangular wave signal is constant even if the period of the rectangular wave signal obtained from the alternating voltage induced in the stator winding is different during constant speed rotation. The present invention aims to realize a speed control device that corrects the period deviation of a rectangular wave signal and performs highly accurate control.

Means for Solving the Problems In order to solve the above problems, the speed control device of the present invention includes a period detection means for detecting the period of an AC signal having speed information of a rotating body, and a detection value of the period detection means is stored. an arithmetic unit that calculates an error output from the detected value and the base value; an i-driving unit that supplies driving power to the rotating body based on the error output; A first deviation amount is calculated from the first period detection value and the normal value of the detection value, a second deviation amount is calculated from the second period detection value and the normal A value, and the first deviation amount is calculated from the second period detection value and the normal value. The present invention is characterized by comprising an error output correction means for correcting the base $ value based on the calculation result when the subtracted value of the second deviation amount is substantially constant.

Effect of the present invention With the above-described configuration, even if the period of the rectangular wave signal obtained from the alternating voltage induced in the stator ω line is different during constant speed rotation, the period of the rectangular wave signal is as if it were constant. Since the shift in the period of the rectangular wave signal is corrected by the arithmetic unit, even if the period of the rectangular wave signal obtained from the induced alternating voltage is shifted, it does not appear as a disturbance in the control system, resulting in high accuracy. control.

EXAMPLE Hereinafter, a speed control device according to an example of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention, which is implemented using a processor.

An alternating voltage signal induced in a stator winding (not shown) of a motor 1 is input to a waveform shaping circuit 2 . The output of the waveform shaping circuit 2 is the chamber L"93a, the calculation 2S3b,
Memory 3c, frequency jjJl detector 3d, data buses 4, 5
．． Channel selector 3 of the processor 3 consisting of 6
a, the channel selector 3a generates an address update signal for the memory 3c of the processor 3, and the address update signal is supplied to the memory 3C of the processor 3 via the control hash 4.

Further, when the waveform shaping circuit 2 outputs an output signal, the timing signal output terminal 3 of the channel selector 3a
A timing signal is outputted from e and supplied to the period detector 3d. The period detector 3d measures the period of the timing signal output from the timing signal output terminal 3e, that is, the period of the output signal of the waveform shaping circuit 2, and sends the measured signal to the memory 3C of the processor 3 via the data bus 6. supply The memory 3C stores periodic data at an address based on the address update signal of the channel selector 3a.

Next, in the processor 3, the speed of the motor 1 is calculated by the calculator 3b from the period data stored in the memory 3C of the processor 3 and the reference speed data set in advance from the period detector 3d via the data bus 6. An error output is calculated and the calculated result is supplied to the digital-to-analog converter 7 via the data bus 5. The output of the digital-to-analog converter 7 is amplified by a power amplifier (indicated as a power amplifier in the figure) 8 and supplied to the motor 1 as driving power.

FIG. 2 is a signal waveform diagram for explaining the period correction operation, and is a signal waveform diagram when the motor 1 is rotating at a constant speed. Figure 2 (a) shows the signal waveform (FC signal) of the alternating voltage induced in the stator winding.
is the output signal waveform of the waveform shaper 2, and FIG. 2(C) is the timing signal output from the timing signal output terminal 3e of the channel selector 3a, and its period is measured and used as speed information. FIG. 2(d) shows the speed error signal calculated by the calculator 3b, and even though the rotational speed of the motor l is constant, the speed error signal is not a constant value and the FC
Each time a signal is input, it becomes larger or smaller than 0°. This is because the cycle of the FC signal is not always constant (it changes every cycle, and may become larger or smaller than the normal value).For example, when the motor l is rotating at the set speed. Assuming that the periods after waveform shaping of the continuous FC signal are PI and P2, and the ratio of Pl:P2 is 98:102, the period detector 3
The detected value of period P1 of d is from time t1 to time L2 in FIG.
The time interval will be 2% shorter than the normal value. Further, the detected value of the period P2 of the period detector 3d is at time t2.
to time t3, and the period value is 2% longer than the normal value.

Furthermore, the same thing will happen in the next cycle from time t3 to time t5, and the time interval from time t3 to time t4 will be 2% shorter than the normal value, and from time L4 to time L5.
The time interval will be 2% longer than the normal value. Therefore, in the continuous FG double signal period, sections shorter and longer than the normal period value appear alternately.

In other words, the arithmetic unit 3 of the processor 3 uses a signal in which the period value of the FC signal appears in sections shorter and longer than the normal value.
When b calculates the speed error output, from time t1 to time t2
In the section where the time interval from time L2 to time t3 is measured, the period is 2% shorter, so this is the speed error output when the speed is 2% faster, and in the section from time L2 to time t3, the period is 2% longer. Therefore, the speed error output is when the speed becomes 2% slower. Therefore, even though the motor l is rotating at the set speed, the error output becomes larger or smaller, which is not desirable for a control system. .

However, in the embodiment of the present invention shown in FIG. 1, when the motor 1 is rotating at a constant speed, it is possible to correct the period deviation even if the ratio of the FG multiplication signal period is not exactly 100:100. The structure is such that a sufficient period ratio can be secured and highly accurate control can be realized, and this will be explained below.

If the first FG multiplication signal section of the continuous FC signal is section A, and the section of the second FC signal is section B, motor l is FC
Control is performed using one cycle of the signal, and control is performed with the FG times the signal cycle alternately shifted. At this time, F
The control characteristic of the motor 1 at a frequency of 1/2 of the C signal is in the inertial region.

Due to the stability of the control system, the control region is approximately 1/2 of the FG frequency.
Since it is about 0, the disturbance response characteristic at a frequency of 1/2 of the FC frequency is about 1/10 of that in the control region.

Nevertheless, due to the shift in the FG multiplication signal period, the error signal is larger than the value obtained from the original response of motor 1. Normally, the response of motor l at half the frequency of the FG signal is almost a disturbance. As a result, the value of the error output remains almost constant.

Using this characteristic, when the continuous FG multiplication signal period becomes thicker (or smaller) alternately, it is determined that the cause is not the response of motor 1 but the period deviation due to the FG multiplication signal, and correction is made. I'll do what I do.

Here, if there is no difference in the period ratio of the FC signal, the period values of the section B and section B will be the same. However, when creating the FC signal, the ratio of PG times the signal period is 100:100.
As a result, the period values of section A and section B will not be the same, but will differ by a value corresponding to the period deviation. If the period deviation U in section B is -ΔA, the period deviation amount in section B is ΔA. That is, the deviated star of the FG double signal period can be found from the difference between the periods of the F interval and the B interval, and is expressed by equation (1).

−A ΔA= ・・・・・・(1)
Here, A and B indicate the values of the circumference of the A section and the B section, respectively. Further, selection of the address of the memory 3c according to the interval B and interval B is performed based on address update No. 13 of the channel selector 3a.

Therefore, the period deviation ΔA of the FC signal is determined, and 'A lii is corrected based on it in each section. That is,
In the A section, the reference value is calculated by -ΔA, and in the B period, the reference value is calculated by +ΔA, so that the deviation in the FG times signal period can be corrected.

The reference value is corrected using equation (2) and (31).

DA=D-ΔA...(2)D
B = D - ΔA (3) Here, is the predetermined reference value of the rotation speed, and DA, D, and 3 are the corrected reference values for the A section and B section, respectively. .

FIG. 2(e) shows the periodic correction amount obtained by the above method, which is a negative value of 11 in the A section and a positive value in the B section.

FIG. 3 shows a full chart of the FC signal period deviation correction by the processor 3 based on the above calculation formula.

Here, we set the detection accuracy of the period detection in the section H and section B to high (
In order to do this (because a single measurement is susceptible to noise, etc.), the data measured several times are averaged, and data with significantly different periods are excluded from the average data. If the number of times of averaging is n, then the average values of the section B and the section B are respectively expressed as equation (1) and equation (4).

ΔA= ...(4) First, in block 301, the period of continuous FC signals is calculated, and in block 302, the offset position is determined from the period of the FC signal, and the difference in the offset positions of consecutive FC signals is approximately Determine whether it is constant. If the difference in eccentric position is not nearly constant, the rotational speed of motor 1 is changing, and the F
The motor 1 is controlled based on the value of one cycle without correcting the G times signal cycle. When the motor l starts rotating at a constant speed, the period of each section A and B is measured in block 303, and it is determined in block 304 whether or not the cycle has been completed 0 times.If the cycle has not been completed 0 times, the cycle in block 303 Return to After calculating the average of each of the sections B and B in section 305, subtract the average value of section A from the average value of section B, and divide the subtraction result by I/2 to obtain the correction amount ΔA.
I'm looking for i16. In block 306, the base c11 values DA and DB after correction are determined. After determining the corrected reference values DA and D,
The process moves on to control of the round 1 and I corrections.

The calculation formula for the speed error output of the calculator 3b after shifting to control with a positive FG period is (2), (Using the corrected reference values DA and D obtained from Formula 31, (5), It will look like type 61.

0A=A-DA...(5)
OB=B-DB ・・・・・・(6)
Here, OA is the speed error output in section A, and 0° is the speed error output in section B.

In this way, the rotational speed reference value is corrected as shown in equations (2) and (3) using the correction value ΔA obtained from equation (4) for the deviation in the period of FCda, resulting in high accuracy. Control becomes possible.

As described above, according to the present embodiment, the deviation in the period of the FC signal is detected from the fact that the difference in the amount of deviation between the period values of successive FC signals becomes almost constant, and the deviation in the period of the FC signal is detected as output correction data in the memory of the processor 3. Since it is stored in FC 3c, the speed error is calculated using the output correction data during constant speed rotation.
It is possible to output an error output that is unaffected by a shift in the signal period, allowing highly accurate control to be achieved.

In this example, the alternating voltage induced in the stator winding of the rotating body was used to create the FC signal, but even if the FC signal is created using other methods, the periodicity will be reduced at half the frequency of the FC signal. If there is a deviation, the present invention will produce sufficient effects.

Also a channel selector using a processor.

Although the arithmetic unit, memory, and period detector are configured, there is no harm in configuring each of them with separate hardware.

Effects of the Invention As described above, the present invention provides a period detecting means for detecting the period of an alternating current signal having speed information of a rotating body, and the period detecting means 1
a memory means for storing a detected value of the stage; a τγ operator for calculating an error output from the detected value and a reference value; and a driving means for supplying U dynamic force to the rotating body based on the error output;
Calculating a first deviation amount from a first period detection value and a positive Ml value of continuous period detection values of the AC signal, and a second deviation amount from a second period detection value and the normal value, Said 1st. An error output correction means for correcting the reference value based on the calculation result when the subtracted value of the second offset position is approximately constant; p:
It is characterized by the fact that it detects the period shift caused by half the frequency of the FC signal by detecting the difference in the deviation position of the values of successive FG multiplied signal periods, and then converts it into reference correction data. Since the reference value correction data is stored in the processor 30 memory 3C during constant speed rotation, the speed error is calculated using the reference value correction data, so it is possible to output an error output that is not affected by the period shift of the FC signal. This has an extremely large effect in that highly accurate control can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a speed control device according to an embodiment of the present invention, FIG. 2 is a signal waveform diagram for explaining circuit operation, and FIG. 3 is a flow chart for explaining reference value correction operation. l... Motor, 2... Waveform shaper, 3
...Processor, 3a...Channel selector, 3b...Arithmetic unit, 3C...
Memory, 3d... Period detector, 4.5.6...
...Data bus, 7...Digital-7-
1 - Roku converter, 8... Power amplifier. Name of agent: Patent attorney Shigetaka Awano (1 person) Figure 1 Ward Cq School diagram

Claims (2)

[Claims] (1) A period detection means for detecting the period of an AC signal having speed information of a rotating body, a memory means for storing a detection value of the period detection means, and an arithmetic unit for calculating an error output from the detection value and a reference value. a driving means for supplying driving power to the rotating body based on the error output; and a first deviation amount from a first period detection value and a normal value of continuous period detection values of the AC signal A second deviation amount is calculated from the second period detection value and the normal value, and when the subtracted value of the first and second deviation amounts is substantially constant, the reference value is corrected from the calculation result. A speed control device comprising error output correction means. (2) Every time the period detecting means detects the period over at least two periods of the AC signal having the speed information of the rotating body, the address of the memory means for storing the detection value of the period detecting means is updated, and the memory means is stored in the arithmetic unit. 2. The speed control device according to claim 1, further comprising a channel selector that compares the cycle data stored at the corresponding address with a reference value and sends an error output to the driving means according to the magnitude thereof.