JPH04127890A - Speed controller for traveling object - Google Patents

Abstract

PURPOSE:To obtain an appropriate correcting torque even when a load abruptly changes by detecting inherent harmonic components in the actual speed varying mode of an electric motor and adjusting the current or voltage command given to a driver from an electronic means so as to remove or reduce the harmonic components. CONSTITUTION:This speed controller is provided with the correcting signal generating means 10 surrounded by the frame of broken lines in the figure as a new element. In other words, this speed controller is provided with a means which executes proportional or proportional and integral control by using a command value which makes the sine and cosine term coefficients of inherent harmonic components of a speed signal nf or speed deviation signal ne by separately calculating the coefficients and adds a correcting signal to a current command Is by producing the correcting signal by calculating the sine and cosine values to the position. While the above example explains the case of one harmonic wave, a plurality of harmonic components can also be coped with by adding similar correcting signal generating means. In addition, any harmonic components and the number of harmonic waves to be detected can be changed freely in accordance with individual subject motors.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a speed control device for a moving body, and in particular, the present invention relates to a speed control device for a moving object, and in particular, for controlling the speed of a control device such as a servo motor that must not have speed fluctuations or position fluctuations during operation. This relates to a control device. In this specification, the term "moving object" refers not only to objects that move themselves or change their speed, but also objects that move a load or whose speed changes when coupled with a load.

[Conventional technology]

In general, servo motors, including drive motors for VTRs (video tape recorders), are required to rotate smoothly, and VTR motors in particular require speed fluctuations, as fluctuations in speed immediately appear as a drop in image quality. It is desired that it be constant. In other words, if there is speed fluctuation (uneven rotation, speed ripple, torque ripple), the image will be distorted and V
The reliability and dignity of a TR will be significantly impaired.

Conventional devices of this type, such as VTRs, have mainly used DC motors, but in recent years, brushless motors whose speeds can be freely and easily changed are increasingly being used.

Precision motors have the advantage that they do not have mechanical brushes, so they do not suffer from problems due to brush or commutator wear or abrasion debris.

However, in a brushless motor of the 120-degree energization type, the number of magnetic flux crossings of the energized coil differs depending on the position of the rotor, which causes torque ripple, resulting in uneven rotation (speed fluctuation) during operation.

In contrast, there is a method that detects only a specific frequency component from among the speed fluctuation components produced by torque ripple, creates a correction torque according to the specific frequency component, and applies it to the energized coil to reduce rotational unevenness. It is disclosed in Japanese Patent Publication No. 1-218380.

[Problem to be solved by the invention]

In the method disclosed in the above-mentioned publication, in the case of a constant speed and a constant load with little variation in the average load, it was possible to always operate in the best condition by determining the correction value only once, but the servo motor For applications where there are such sudden load fluctuations, there is a problem in that the formation of correction torque cannot keep up and smooth operation cannot be achieved.

The purpose of the present invention is to
It is an object of the present invention to provide a speed control device for a moving body that can quickly reduce torque ripple, speed fluctuation, etc.

More specifically, it is an object of the present invention to provide a VTR in which the rotational speed of a servo motor is smooth and image disturbance is extremely small.

[Means to solve the problem]

In order to achieve the above object, the present invention includes a speed detection element that detects the moving speed of a moving body, and an appropriate current command or voltage command based on the deviation between the detected speed and a command speed given from the outside. A speed control device for a moving object, comprising: speed control means for applying speed control to the moving object; means for detecting harmonic components inherent in the speed fluctuation mode obtained by the speed detection circuit; and means for reducing the detected harmonic components. The present invention proposes a speed control device for a moving body, comprising means for adding a correction value to the current command or voltage command.

The speed detection element includes a means for detecting the moving speed of the moving object by dividing it into a sine wave component and a cosine wave component, and the speed control means detects the moving speed of the moving body by dividing it into a sine wave component and a cosine wave component, and the speed control means divides the current command or voltage command into a sine wave component and a cosine wave component. The internal harmonic component detection means includes means for detecting harmonic components separately into a sine wave component and a cosine wave component, and the correction current command or voltage command addition It is desirable that the means is a means for dividing the corrected current command or voltage command into a sine wave component and a cosine wave component and adding them.

The present invention consists of 1. The invention also includes a speed detection element for detecting the moving speed of the moving object, and a speed control means for giving an appropriate current command or voltage command to the moving object based on the deviation between the detected speed and a command speed given from the outside. A speed control device for a moving body including means for detecting harmonic components inherent in the speed fluctuation mode obtained by the speed detection circuit, and a correction value for reducing the detected harmonic components in the current command or voltage command. The present invention proposes a speed control device for a moving body, comprising: means for adding the amount of load on the moving body; means for detecting the amount of load on the moving body; and means for further modifying the correction value based on the relationship between the correction value and the amount of load. It is something.

In this case as well, the speed detection element includes means for detecting the moving speed of the moving object by dividing it into a sine wave component and a cosine wave component, and the speed control means detects the moving speed of the moving body by dividing it into a sine wave component and a cosine wave component. the internal harmonic component detecting means includes means for detecting the harmonic component separately into a sine wave component and a cosine wave component, and the correction current command Alternatively, it is preferable that the voltage command addition means is a means for dividing the corrected current command or voltage command into a sine wave component and a cosine wave component and adding them.

Further, if the device is provided with means for stopping the function of the correction value modifying means when the change in the load amount is small, control can be performed more quickly and accurately.

In either case, the moving body may specifically be a rotating or linearly driven electric motor.

In particular, brushless motors are optimal.

Viewed from a different perspective, the present invention includes a control device that controls and drives a device, a driver that applies current or voltage to the controlled device based on a command value given from the control device, and a control device that controls the actual state of the controlled device. an element for detecting the operating state of the electrical signal as a current or voltage; a means for detecting harmonic components included in the detected electrical signal; a means for generating a correction signal for canceling the detected harmonic components; The present invention proposes a device drive control device that includes means for calculating a load amount of a control device, and means for further modifying the correction signal based on the relationship between the calculated load amount and the correction signal.

The present invention is particularly suitable for controlling the rotational speed of a servo motor of a VTR.

[Effect]

In the present invention, the harmonic component detecting means usually detects harmonic (frequency) components inherent in the actual speed fluctuation mode of the motor and removes or reduces the detected harmonic components by using a microcomputer or the like. adjusts the current command or voltage command given to the driver from electronic means.

At this time, if the means for calculating the relationship between the load amount detected by the load amount detection means and the correction value standardizes the relationship between the load amount and the correction value and stores it in advance in the form of a correspondence table, it is possible to In some cases, an appropriate correction torque can be created quickly, and smooth rotations and other movements can be achieved.

〔Example〕

Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 2 is a block diagram showing an embodiment of the speed control device according to the present invention in which the moving body is a brushless motor.

In FIG. 2, M is a motor serving as a moving body, which causes periodic torque fluctuations and speed fluctuations within one rotation. The motor M may be either a rotary type or a linear type, and may or may not have brushes.

Brushless motors are more convenient. This motor is coupled to a load. PS is a magnetic pole position detector that detects the position of the motor M, especially the rotor. The detection signal is used to switch the phase current of motor M. Although the internal structure of the motor is not shown, brushless motors are generally configured to electronically detect the position of the rotor and to apply current to two phase windings selected according to the position of the rotor. There is. E is a speed detector consisting of an encoder etc. attached to the rotating shaft of the motor M. As a speed detector,
In addition to encoders, frequency generators, tacho generators,
A pulse generator etc. can also be used.

The speed control means C includes a microcomputer MC, an automatic current adjustment circuit ACR, and a driver, that is, an inverter INV.
The main components are a speed detection circuit C0UNT and a speed detection circuit C0UNT. Microcomputer MC has the functions described below. A.C.
R is an automatic current adjustment circuit (Automatic Curr)
ent Regulator), and the current transformer C
The current detection value obtained at T is taken in. An INV is an inverter that serves as a driver for driving a motor, and normally consists of six switching elements to form three arms each for positive and negative arms, and current is passed through two selected phase windings of these to determine the magnitude of the current. It can be changed.

C0UNT is a speed detection circuit, which actually consists of a counter, and detects the speed based on the number of pulses or pulse intervals detected at a constant sampling time.

The speed obtained by the speed detection circuit C0UNT is output to the microcomputer MC. The signal from the magnetic pole position detector PS is sent to the microcomputer MC and inverter NV.
is output to. The microcomputer MC processes these signals, controls on/off of the switching elements of the inverter INV, and adjusts the magnitude of the current value.

As shown in FIG. 3, the microcomputer MC includes an arithmetic unit ALU, a counter CNT, a D/A converter DA, and a storage unit MRY as internal functions.

The counter CNT measures the period of the pulse signal from the encoder E, and calculates the speed as the reciprocal of the period. Arithmetic unit A
LU receives the signal from the counter and stores R in the storage unit MRY.
The speed error is calculated by comparing it with the command speed stored in the OM. Next, a correction signal is created based on the calculated speed error.

The calculation unit ALU stores this correction signal in the RAM of the storage unit MRY.
The data is stored at any time and updated sequentially with new data. Furthermore, the calculation unit ALU also includes an element for detecting harmonic components inherent in the detected actual speed mode of the motor M. This detection of harmonic components is performed by comparing the fundamental wave component with, for example, the third or fifth harmonic component, which particularly causes torque ripple. Note that although the counter CNT is shown as an external one, the counter CNT is
Of course, it may be built into C.

FIG. 1 is a block diagram showing a more specific embodiment of the speed control device according to the present invention.

In FIG. 1, the speed signal is calculated by counting the number of pulses of a reference oscillator (clock or counter in a microcomputer) that falls between the pulses of a speed detector (encoder) E, and taking the reciprocal of the number. The speed signal n thus obtained is taken into the microcomputer.

In the microcomputer, software calculates a speed deviation signal ne from the difference between the speed command ns and the speed signal n, and outputs a comparison/integral control (a new current command after PI sub-control processing).

The current control system is configured as hardware, and the speed command n
Current command given based on s 5 and current transformer CT
A current error Ie is calculated from the current detection value obtained from , and current is supplied to the motor M via the automatic current regulator ACR.

Note that in FIG. 1, illustration of the inverter is omitted.

Although the overall configuration of these components is similar to that conventionally known, this embodiment includes a correction signal generating means 10 shown in a broken line frame in FIG. 1 as a new element. In other words, the sine term coefficient and cosine term coefficient of any harmonic (frequency) component inherent in the speed signal n P
control) or proportional/integral control (PI control), calculates the sine and cosine values for the position, creates a correction signal, and adds this to the current command Is. Although an example of − number of harmonics is shown here, it is also possible to deal with a plurality of harmonic components by providing a similar correction signal generating means.

Furthermore, the arbitrary harmonic components and number to be detected can be freely changed depending on each target motor.

The present invention further includes a load amount detection means and a means for calculating the relationship between the load amount and the correction value, and the P
It is characterized in that it includes means for correcting the value of the I control output. Torque ripples that generally cause speed fluctuations include those that are constant regardless of the load, such as cogging torque, and those that are proportional to the load, such as the torque constant of a motor, which varies depending on the rotational position.

Therefore, by means of calculating the relationship between load amount and correction value,
By learning the value of the correction value corresponding to the load, when the load fluctuates, the response can be made faster by correcting the correction value by an amount corresponding to the amount of load fluctuation obtained by the load detection means.

Next, the principle of reducing speed ripple using the speed control device of the present invention will be explained.

FIG. 4 shows the speed fluctuation per rotation of the motor M.

The number of pulses generated by the encoder E per rotation is N, and the calculation for speed detection is performed once at one pulse interval. The speed n1 is determined as the reciprocal of the number of reference oscillator pulses of the microcomputer that fall into each pulse interval of the encoder E. The speed signal measured by the actual speed detection counter is as shown in FIG.

Generally, the speed nf(θ) can be expanded into each frequency component according to the following equation.

nt(θ)=no 10Σa n51n nθ+b ncO
8no... (1) n = square, no...DC component, an...sine term coefficient.

bn...Cosine term coefficient, n...Number of pulsations per rotation Figure 4 shows only (1) Omukai's rotational unevenness component. n for any frequency component. Jan? The absolute value of bn is expressed by the following equation.

no=-f nf(θ)dθ =・(2)2
π −π an=-! −/7cnf (θ) 5innθdθ
-(3)2π -π Here, for each sine product coefficient an and cosine term coefficient bn for an arbitrary frequency component, integral control is performed to set these to zero (proportional-integral control is shown in Fig. 1, but here (Displayed only with integral control for simplicity),
A correction signal with a phase opposite to the torque ripple can be generated. Therefore, rotational unevenness is reduced. Sine term coefficient Q of correction signal
n H cosine term coefficient d. can be calculated using the following formula.

Cnl = Q nl'-1+ k X aul
...(5) dn+=dnt-++kXbnt
++ (6) Here, the subscript it t-1
t and i- respectively represent the value of the rotation.

FIG. 4 shows an example in which rotational unevenness is caused by a torque ripple component having a period of once per rotation, and shows a method of detecting a pulsation component in the rotational unevenness to form a correction signal. The sampling period for correction is once/one revolution.

Here, for example, since the torque constant varies with the rotational position, such as in a 120-degree energized brushless motor,
If torque ripple occurs, it is necessary to form new sine and cosine coefficients of the correction signal when the load changes.

It takes several revolutions for the new correction signal to balance the torque ripple and reduce uneven rotation.

On the other hand, there is generally a certain relationship as shown in FIG. 5 between the load amount, the sine term coefficient C11 of the correction signal, and the cosine term coefficient dn of the correction signal. The reason why the sine term coefficient OnH cosine term coefficient dn of the correction signal does not become zero even when the load is zero is because there is a torque fluctuation component that does not depend on the load, such as cogging torque. Here, as shown in FIG. 1, a load amount (in this case, expressed as an average value of motor current) detection means is provided, and a sine term coefficient Cn of a correction signal with respect to the load amount is provided.
1 cosine term coefficient d. Means for constantly detecting the relationship between Cn and H
and means for correcting the cosine term coefficient dn correction signal,
Even if there are large load fluctuations, it can be dealt with immediately and smooth rotation can be maintained.

Note that when the change in the load amount is small, it is desirable to have a means for stopping the function of the means for correcting the correction signal. In that case, there is no need to execute calculations for this correction, so the control becomes more efficient. done quickly.

FIG. 6 is a flowchart of the processing procedure when the method of the present invention is implemented by a microcomputer. Here, as described above, an example will be shown in which the torque fluctuation occurs once per rotation. It is also assumed that speed control is performed every time an encoder signal is input.

In steps (2) and (2), the speed command ns and the speed n are taken.

In step (2), a speed error ne is calculated from the taken-in speed command ns and the actual speed n by ne''nsnf.

In step (2), a proportional term P for P control is calculated using p=-ne.

In step (2), it is determined whether the sampling time for calculating the coefficient of the frequency component of the speed ripple (fluctuation) has been reached.

If it has been reached, in step ■, (2), (3)
Calculation of the sine term coefficient any cosine term coefficient bn of speed fluctuation is performed using the formula.

In step (2), the sine term coefficient Cn H cosine term coefficient d of the correction value. Calculate.

In step (2), the average load amount for one rotation is calculated, and a relational expression between the load amount and the sine term coefficient cn and cosine term coefficient of the correction value is calculated.

In step (3), calculations are performed every few pulses of the encoder, and if the variation in the correction amount is large, the correction value is changed. This modification of the correction value is based on the fifth
This is performed based on the relationship between the sine term coefficient C0 and cosine term coefficient dn of the correction values shown in the figure and the load amount.

In step [phase], a current command output is output based on the speed control proportional term calculation result and the correction value calculation result.

As a result of the above, a speed control device with very good followability to load fluctuations can be obtained. Note that in the above processing procedure, the current value was evaluated as the load, but if the load changes with the number of rotations, the number of rotations may be used.

In addition, although the speed control device was explained in FIG. 1, in general, there is a control device that drives a controlled device, and a current or voltage is applied to the controlled device based on a command value given from this control device. In a system including a driver and an element that detects the actual operating state of a controlled device as a current or voltage, the control device detects a harmonic component contained in an electrical signal detected by the element. and 1. The function of generating a correction signal that cancels out the harmonic components detected by this means, the means of calculating the amount of load on the controlled equipment, and the function of calculating the relationship between the correction signal and the amount of load and generating the correction signal based on that. It will be obvious that the present invention can also be applied to other control devices, such as position control devices, torque control devices, etc., provided that they are provided with means for modifying the amount.

Further, in the above embodiments, PI control has been described as an example of the control mode, but the present invention can be implemented in combination with various control modes as long as the control mode includes at least one of the PIs.

In particular, when the present invention is applied to a speed control device for a servo motor of a VTR, image deterioration is significantly reduced compared to a conventional VTR.

〔Effect of the invention〕

According to the present invention, it is possible to provide an electric motor speed control device that can reduce speed fluctuations of an electric motor and has a quick response to load fluctuations and the like.

This invention can also be applied to linear type electric motors.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a correction signal generating means of an embodiment of the speed control device for a moving body according to the present invention, and FIG. 2 shows the overall configuration of an embodiment of the speed control device for a moving body according to the present invention. 3 is a block diagram showing the internal configuration of the microcomputer, FIG. 4 is a diagram showing the relationship between rotational unevenness of the controlled object of the present invention and the correction signal, and FIG. 5 is a diagram showing the relationship between the load amount and the correction signal. FIG. 6 is a flowchart showing the processing procedure when the present invention is implemented by a microcomputer. ACR... automatic current adjustment circuit, ALU... calculation unit,
C...Speed control means, CNT...Counter, C0U
NT...Speed detection circuit, CT...Current transformer, D
A...D/A converter, E...speed detector, engineering N
V...Inverter (driver), M...Motor, M
C...Microcomputer, MRY...Storage unit,
ps...Magnetic pole position detector.

Claims (1)

[Claims] 1. A speed detection element that detects the moving speed of a moving body, and an appropriate current command or voltage command to the moving body based on the deviation between the detected speed and a command speed given from the outside. A speed control device for a moving object, comprising: means for detecting a harmonic component inherent in the speed fluctuation mode obtained by the speed detection circuit; and a correction value for reducing the detected harmonic component. A speed control device for a moving body, comprising: means for adding to the current command or the voltage command. 2. The speed control device for a moving body according to claim 1, wherein the speed detection element includes means for detecting the moving speed of the moving body by dividing it into a sine wave component and a cosine wave component, and the speed control means includes means for dividing a current command or a voltage command into a sine wave component and a cosine wave component and applying them to the moving body, and the intrinsic harmonic component detecting means divides the harmonic component into a sine wave component and a cosine wave component. A moving body characterized in that the correction current command or voltage command addition means is a means for dividing and adding the correction current command or voltage command into a sine wave component and a cosine wave component. Speed control device. 3. A speed detection element for detecting the moving speed of the moving object, and a speed control means for giving an appropriate current command or voltage command to the moving object based on the deviation between the detected speed and the command speed given from the outside. A speed control device for a moving body comprising means for detecting a harmonic component inherent in the speed fluctuation mode obtained by the speed detection circuit, and a correction value for reducing the detected harmonic component in the current command or voltage command. a means for detecting a load amount of the moving object; and a means for further correcting the correction value based on the relationship between the correction value and the load amount. Control device. 4. The speed control device for a moving object according to claim 3, wherein the speed detection element includes means for detecting the moving speed of the moving object by dividing it into a sine wave component and a cosine wave component, and the speed control means includes means for dividing a current command or a voltage command into a sine wave component and a cosine wave component and applying them to the moving body, and the intrinsic harmonic component detecting means divides the harmonic component into a sine wave component and a cosine wave component. A moving body characterized in that the correction current command or voltage command addition means is a means for dividing and adding the correction current command or voltage command into a sine wave component and a cosine wave component. Speed control device. 5. The speed control device for a moving body according to claim 3 or 4, further comprising means for stopping the function of the correction value correction means when the change in the load amount is small. Device. 6. The speed control device for a moving body according to any one of claims 1 to 5, wherein the moving body is an electric motor that drives rotationally or linearly. 7. The speed control device for a moving body according to claim 6, wherein the electric motor is a brushless motor. 8. A control device that controls and drives the device; a driver that applies current or voltage to the controlled device based on a command value given from the control device; means for detecting harmonic components included in the detected electrical signal; means for generating a correction signal to cancel the detected harmonic components; and calculating the load amount of the controlled equipment. What is claimed is: 1. A drive control device for equipment, comprising: means for further modifying the correction signal based on the relationship between the calculated load amount and the correction signal. 9. A speed detector that detects the rotation speed of a servo motor that drives the rotating head and magnetic tape transport system; and speed control means that provides a current command or a voltage command to the servo motor based on the deviation between the detected speed and a predetermined speed. VTR including
, comprising means for detecting harmonic components inherent in the speed fluctuation mode obtained by the speed detector, and means for adding a correction value for reducing the detected harmonic components to the current command or voltage command. A VTR characterized by this. 10. The VTR according to claim 9, wherein the speed detector includes means for detecting the rotational speed of the servo motor by dividing it into a sine wave component and a cosine wave component, and the speed control means detects a current command or a cosine wave component. comprising means for dividing a voltage command into a sine wave component and a cosine wave component and applying them to the servo motor, wherein the intrinsic harmonic component detecting means detects the harmonic component by dividing it into a sine wave component and a cosine wave component. A VTR characterized in that the corrected current command or voltage command adding means is a means for dividing the corrected current command or voltage command into a sine wave component and a cosine wave component and adding them. 11. A speed detector that detects the rotational speed of a servo motor that drives the rotary head and magnetic tape transport system; and speed control means that applies a current command or voltage command to the servo motor based on the deviation between the detected speed and a predetermined speed. including VT
R includes means for detecting harmonic components inherent in the speed fluctuation mode obtained by the speed detection circuit, means for adding a correction value for reducing the detected harmonic components to the current command or voltage command, and the servo motor. A VTR comprising: means for detecting a motor load; and means for further correcting the correction value based on the relationship between the correction value and the load. 12. In the VTR according to claim 11, the speed detection element includes means for detecting the rotational speed of the servo motor by dividing it into a sine wave component and a cosine wave component, and the speed control means detects a current command or a cosine wave component. comprising means for dividing a voltage command into a sine wave component and a cosine wave component and applying them to the servo motor, wherein the intrinsic harmonic component detecting means detects the harmonic component by dividing it into a sine wave component and a cosine wave component. A VTR characterized in that the corrected current command or voltage command adding means is a means for dividing the corrected current command or voltage command into a sine wave component and a cosine wave component and adding them. 13. The VTR according to claim 11 or 12, further comprising means for stopping the function of the correction value correcting means when the change in the load amount is small.
R.