JPH0322888A - Speed controller - Google Patents

Abstract

PURPOSE:To allow this device to control the speed with high precision by correcting the period of a rectangular wave signal to be constant even if what is obtained by alternating voltage induced to a stator winding is different in a constant speed rotation. CONSTITUTION:The output of a waveform shaping circuit 2 is supplied to a channel selector 3a of a processor 3 composed of a channel selector 3a, a computing element 3b, a memory 3c, a period detector 3d and data buses 4 to 6. Even if the period of a rectangular wave signal obtained from alternating voltage induced to a stator winding is different in a constant speed rotation, the period slippage of the rectangular wave signal is corrected so that the period of the rectangular signal may be fixed. A highly precise control of speed can thereby by performed even if the period obtained from the induced alternating voltage is different as it does not appear as a disturbance to a control system.

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 generator to the rotating body. A method using a shaped signal (FC signal) (for example, "Brushless DC motor drive system that omit position detection element" National Technical Report p614 Vol. 33
No. 5 OCT. 1987), speed control is performed using only the frequency or repetition period of the FC signal as speed information, and it is possible to relatively stably control the speed of a rotating body with a simple structure (for example,
This is shown in Publication No. 434. ) By the way, this frequency or period detection method assumes that the alternating voltage induced in the stator winding is sufficiently amplified until it becomes a rectangular wave signal, and that a predetermined edge of the rectangular wave signal has speed information. and generates an error output signal.

For example, in a typical period detection method, clock pulses are counted in the period from one leading edge to the next leading edge of an amplified alternating voltage rectangular wave signal. It is possible to obtain the current count value and create a pulse width modulation signal (used when using the Chonopa type drive method) based on this count value, or convert the count value to an analog voltage. The error output is obtained.

Therefore, when trying to achieve more precise control,
At a constant rotation speed, the alternating voltage induced in the stator winding must be the same, and the period of the square wave signal must be made more accurate.

Problems to be Solved by the Invention However, in the horizontal command as described above, for example, it is possible to rotate a rotating body consisting of 12 poles (6 pole pairs) in the rotor and 9 coils in the stator using a three-phase half-wave drive system. The period of the rectangular wave signal obtained by amplifying the alternating voltage induced in the stator winding when Since periods longer and shorter than the normal period appear alternately in the control system, a disturbance with a frequency of 1/2 of the frequency of the square wave signal appears in the control system, deteriorating the control characteristics. . In particular, in control systems that require highly precise rotation, such as the cylinder motor of a video table recorder (VTR),
The frequency of the disturbance was a problem even though it was in the inertial region of the control system. Furthermore, since almost no adjustment is made during mass production, it is difficult to accurately manage 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 aim is to realize a speed control device that corrects the period deviation of the 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 uses a frequency I that detects the period of an AC signal having speed information of a rotating body.
Ill detection means, memory means for storing the detection value of the period detection means, an I/I calculator for calculating an error output from the reference value such as the detection value, and a driving power for the rotating body based on the error output. Calculates the first and second deviation amounts from the driving means to supply and the continuous first and second period detection values and normal values stored in the memory means, and calculates the first and second deviation amounts Correction that calculates a correction value of the error output from the calculation result when the subtracted value of the quantity is approximately constant (i! calculation means, and the correction value causes the arithmetic unit to detect the error caused by the period detection at each period detection point). The present invention is characterized by comprising an error output correction means for correcting the output, and a gain switching means for switching the gain of the control system when the correction value calculation means operates.

Effect of the present invention The present invention provides an advantage that even if the frequency of the rectangular wave signal obtained from the alternating voltage induced in the stator winding due to the above-mentioned horizontal angle differs during constant speed rotation. Since the period deviation of the rectangular wave signal is corrected by the arithmetic unit as if the period of the rectangular wave signal were constant, the period of the rectangular wave signal obtained from the induced alternating voltage may be deviated. Highly accurate control can be performed without any disturbance appearing in the control system.

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. Waveform shaping circuit 2
The output of the processor 3 is supplied to the channel selector 3a of the processor 3, which is composed of a channel selector 3a, an arithmetic unit 3b, a memory 3c, a period detector 3d, and a data path 4.5.6. An address update signal is generated, and the address update signal is supplied to the memory 3c of the processor 3 via the control bus 4.

Further, when the waveform shaping circuit 2 outputs an output signal, a timing signal is outputted from the timing signal output terminal 3e of the front δ channel selector 3a 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 supplies it to the memory 3c of the processor 3 via the data bus 6. do. 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 processor 3b calculates the data from the cycle detector 3d via the data bus 6 in the memory 3c of the processor 3 based on the cycle data and the reference speed data set in advance. The speed error output of the motor l is calculated, and the calculation result is supplied to the digital-to-analog converter 7 via the data hub 5.The output of the digital-to-analog converter 7 is sent to a power amplifier (in the figure, a power amplifier and a power amplifier). ) 8 and is 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.
1) is the output signal waveform of the rectangular shaper 2, and FIG. 2(C) is the timing signal output from the timing signal output terminal 3e of the channel selector 3a, and the period thereof 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 every time the FG signal is manually input. It becomes larger or smaller than "0". This is because the period of the FG signal is not always constant, but changes every period, and becomes larger or smaller than the normal value. For example, when the motor 1 is rotating at the set speed, the period after waveform shaping of the continuous FG signal is P,, P2, and p,
:p2 ratio is 98:l02, the detected value of the period JIJI P of the period detector 3d is the time interval from time t1 to time L2 in Fig. 2, which is 2% shorter than the normal value. It becomes the value. Also, the period P2 of the period detector 3d
The detected value is the time interval from time L2 to time t8, and the period value is 2% longer than the normal value.Furthermore, the same is true for the next period from time L3 to time t5, and from time t3 to The time interval from time t4 to time t4 is 2% shorter than the normal value, and the time interval from time t4 to time t5 is 2% longer than the normal value. Therefore, in the period of the continuous FC signal, sections shorter and longer than the normal period value appear alternately.

In other words, the processor 3 of the pro sensor 3 uses a signal in which the period value of the FG signal appears in sections shorter and longer than the normal value.
When b calculates the speed error output, from time L1 to time t2
In the section where the time interval from time t2 to time t8 was 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 t2 to time t8, the period is 2% longer. Therefore, this is the speed error output when the speed is 2% slower. Therefore, even though the motor 1 is rotating at the set speed, the error output increases or decreases, which is not desirable as 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, even if the ratio of the periods of the FC signal is not exactly 100100, it is possible to correct the period deviation. It is designed to ensure a sufficient period ratio and realize highly accurate control.
The process will be explained below. If the section of the first FC signal of the continuous FC signals is section A, and the section of the second FC signal is section B, the motor 1 is
The control is performed with one cycle of the signal, and the cycle of the FC signal is alternately shifted. At this time, F
The control characteristic of the motor 1 at a frequency of 1/2 of the C signal is an inertial region, and the control region is 1/1 of the frequency of the FC signal.
2, the disturbance suppression characteristic at a frequency of 1/2 of the FC signal is approximately 1/6 of that in the control II fil region. Nevertheless, due to the shift in the period of the FG signal, the error signal is larger than the value obtained from the original response of the motor 1. 1/ of normal FG signal
The response of the motor 1 at frequency No. 2 is hardly affected by disturbances, and as a result, the value of the error output is also almost constant.

However, since the period of the FC signal is measured with high precision while operating the control system, the control system will affect the measurement system. Therefore, in order to measure the period of the FC signal with higher precision, it is necessary to lower the gain of the control system so that the influence of the control system is less likely to appear on the measurement system. Therefore, when measuring the period of the FC signal with high precision, the gain of the control system is lowered using the gain switching means.
Calculate the correction value using the correction value calculation means. After the correction value is calculated by the correction value calculation means, the gain is returned to the original value by the gain switching means so that normal control characteristics can be obtained. The deviation in the period of the FC signal is detected by using the characteristic that the error output of the motor l at a frequency of 1/2 of the FG signal is almost constant. That is, when the period of successive FC signals alternately increases or decreases, it is determined that the cause is not the response of the motor 1, but a period shift caused by the FG signal, and correction is made. When the rotational speed of motor l is constant, if there is no difference in the period ratio of the FG signal, the period values of section A and section B will be the same. However, since the period ratio of the FC signal deviates from too:too when the FG signal is activated, the period values of the 8th section and the B section are not the same, but differ by a value corresponding to the period shift. If the period deviation amount in the 8th section is -ΔA, the period deviation amount in the B section is ΔA.

That is, the amount of shift in the period of the FC signal can be determined from the difference in the amount of deviation between the eight sections and the B section, and is expressed by equation (1).

(B-D) - (A-D) ΔA-...
...(1)2 Here, A and B indicate the period values of the A section and B section, respectively, and D indicates the normal value. At this time, the gain of the control system is set smaller than normal by the gain switching means. In addition, the selection of the address of the memory 3C according to the 8th section and the B section is performed based on the address update signal of the channel selector 3a. The deviation in the period of the FG signal is corrected by calculating +ΔA on the deviation amount obtained from the measured period value, and in the B section, calculating - ΔA on the deviation amount obtained from the measured period value. can do. FIG. 2 (81 is the cycle correction value obtained by the above method, which has a negative value in the A section and a positive value in the B section.

FIG. 3 shows a flowchart for correcting the FC signal period deviation by the processor 3 based on the above calculation formula. Here, in order to increase the detection accuracy of period detection in the 8th section and the B section (because one measurement is weak against noise, etc.), we will average the measurements taken several times, and if the periods differ greatly, we will Exclude from average data. If the number of times of averaging is n, then the average values of the deviations in the six sections 1 and B are expressed as Σ (Ai i-1 D)/n and Σ (Bi-D)/n, respectively. ．． Therefore, equation (1) becomes equation (2).

2...(2) First, the bronch 301 calculates the period of continuous FG signals, and the branch 302 calculates the amount of deviation from the period of the FG signal, and calculates the difference in the amount of deviation of successive FC signals. Determine whether it is approximately constant. If the difference in deviation is not almost 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 cycle of the C signal. When the motor 1 starts rotating at a constant speed, the gain of the control system is reduced by the gain switching means in the block 303. Next, block 304
The deviation amounts for each of the A section and the B section are calculated in step 305, and it is determined in branch 305 whether or not the process has been completed n times. If the process has not been completed n times, the process returns to block 304. If n times are completed, block 306 indicates the A section. After finding the average of the deviation amounts for each section B, the average value of the eight sections is subtracted from the average value of the B section, and the subtraction result is 1/2 to obtain the correction value ΔA. After determining the correction value ΔA, block 307
The gain of the control system is returned to the normal value by the gain switching means.

Then, the process moves to control of FG cycle correction of the blower block 30B.

In the flowchart of FIG. 3, the correction value ΔA is obtained from the deviation amount of each of the sections A and B, but it is also possible to obtain it from each period. That is, if the normal value D is not taken into account in equations (1) and (21), the captured value will be calculated only from the detected values of the cycles of the AB sections.

The calculation formula for the speed error output of the IliI calculator 3b after shifting to FC cycle correction control is (3). It becomes as shown in equation (4).

OA-A-D+ΔA (3
)08-B-D-ΔA ・・・・・・(
4) Here, 09 is the speed error output of the 8th section, and 08 is the speed error output of the B section. In this way, the speed error output is corrected as shown in equations (3) and (4) using the correction value ΔA obtained from equation (2) for the shift in the period of the FC signal, so highly accurate control is possible. It becomes possible.

As described above, according to the present embodiment, a shift in the cycle of the FG signal is detected by the fact that the deviation amount of the cycle value of the continuous FC signal becomes almost constant, and the error output correction value is detected by the processor 3.
Since the speed error is calculated using the error output correction value during constant speed rotation, it is possible to output an error output that is not affected by the period shift of the FG signal, resulting in high accuracy. control can be realized. Furthermore, when calculating the error output correction value, the gain of the control jn system is lowered by the gain switching means, so it is possible to obtain the correction value with higher accuracy.

In this example, the alternating voltage induced in the stator winding of the rotating body was used to generate the FC signal, but even if the FC signal is generated using other methods, the periodicity at the 172 frequency of the FC signal is If there is a deviation, the present invention will exhibit sufficient effects.

In addition, a processor is used to create a channel selector and arithmetic unit. memory. Period detector. Although the error output correction means and the gain switching means have been constructed, there is no harm in constructing each with separate hardware.

Effects of the Invention As described above, the present invention includes a period detecting means for detecting the period of an AC signal having speed information of a rotating body, a memory means for storing a detected value of the period detecting means, and a method for detecting the detected value and a reference value. an arithmetic unit that calculates an error output from the error output; a drive unit that supplies driving power to the rotating body based on the error output; The first and second deviation amounts are calculated from the values, and the first and second deviation amounts are calculated from the first and second deviation amounts. a correction value calculating means for calculating a correction value for the error output from the calculation result when the subtracted value of the second deviation amount is substantially constant; and a gain switching means for switching the gain of the control system when the correction value calculation means is operated. The period deviation occurring at the frequency of During high-speed rotation, the speed error is calculated using the error output correction value, so it is possible to output an error output that is not affected by the period shift of the FC signal, making it possible to achieve highly accurate control i3m. be effective. Furthermore, when calculating the error output correction value (i), since the gain of the control system is lowered by the gain switching means, it is possible to obtain the correction value with higher accuracy.

[Brief explanation of drawings]

FIG. 1 is a bronch diadem 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 flowchart for explaining error correction operation. ．． l...Motor, 2...
... Waveform shaper, 3... Processor, 3a.
...Channel selector, 3b ... Arithmetic unit, 3c ... Memory, 3d ... Period detector, 4.5.6 ... Data path ,7...
・Digital analog converter, 8...Power amplifier.

Claims (3)

[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 driving means for supplying driving power to the rotating body based on the error output; a correction value calculating means for calculating a deviation amount and calculating a correction value for the error output from the calculation result when a subtracted value of the first and second deviation amounts is substantially constant; Speed control comprising error output correction means for causing the arithmetic unit to correct the error output due to period detection at each cycle detection time, and gain switching means for switching the gain of the control system when the correction value calculation means is operated. Device. (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. (3) A claim characterized in that the gain of the control system is made smaller than normal by the gain changing means during operation of the correction value calculation means for calculating the correction value from the subtracted value of the first and second deviation amounts. (1) Speed control device as described.