JPH0648446B2 - Motor control device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a motor control device for controlling the speed and position of a movable object driven by a motor.

[Prior art]

Many methods for controlling the speed and position of a motor are known, and for example, a method using a phase locked loop (hereinafter referred to as PLL) is widely used. In the speed and position control using this PLL, the output frequency ₀ and the phase approach the command value frequency and phase while undergoing frequency modulation. Here, the command speed and the position are reached in a short time when the gain of the high frequency region of the PLL (hereinafter, abbreviated as high region) is high, but when the error amplifier has an integral element, overshoot is well known. Then, the vibration finally repeats vibration around the speed and position of the command value and finally reaches the command speed and position. If such an overshoot occurs, the time required to reach the speed and position as command values, that is, the pull-in time becomes long, which is not desirable. The "pull-in" is "convergence" in automatic control theory and mathematical function theory, and means that the control value matches the target value of the control system. Therefore, measures are taken to keep the gain in the high frequency band low so as not to cause overshoot, but as a result, the time to reach the command speed and command position is prolonged. Also,
A difference counter for generating a speed difference between the commanded speed / position and the actual speed / position and a numerical value according to the position difference, and a D / A.
There is also a method in which a converter and a driver are provided and the motor is controlled by this driver so that the speed difference and the position deviation become zero. However, this method also has a high high-frequency gain and an integrating element in the error amplifier. However, it has been impossible to eliminate the drawback that the overshoot occurs in the case of holding it and the pull-in time becomes long when the high-frequency gain is low.

[Problems to be Solved by the Invention]

The present invention eliminates the drawbacks of the motor control device according to the related art and provides a motor control device that has an integral element in the error amplifier, is excellent in responsiveness, and has no offset. is there.

[Structure of Invention]

As described in the claims, the present invention provides a combination of the difference between the command value speed and the actual speed (speed difference ΔV) and the difference between the command value and the actual position (phase difference Δφ), ΔV, Δ
The detection means for detecting whether or not a predetermined condition on the φ plane is satisfied, and the voltage across the integrating capacitor connected in parallel to the operational amplifier according to the output of the detection means when the predetermined condition is satisfied are It is characterized by a motor control device having means for promptly updating to zero or a predetermined value.

〔The invention's effect〕

According to the motor control device of the present invention, the speed and position as command values are quickly drawn, and there is no offset, and overshoot is also prevented. Therefore, accurate digital positioning is possible, and it is possible to advantageously carry out control of motors used in various automatic control devices and the like.

〔Example〕

Hereinafter, a motor control device according to the present invention will be disclosed with reference to the accompanying drawings. FIG. 1 is a block diagram showing the configuration of a control device which is the basis of the present invention. According to the figure, the output e of the difference counter 1 for obtaining the difference (hereinafter referred to as “deviation”) between the number of pulses of the reference input signal _s and the frequency ₀ indicating the actual number of rotations of the motor is digital-in the D / A converter 2. Converted to analog. Deviation e of D / A converter 2
Is a signal indicating the deviation of the position of the DC motor 4, and this deviation e is input to the differentiator 11 and the function generator 12, respectively.

The differentiator 11 differentiates the deviation e to generate a speed difference detection value V _d , and this output is input to the-side input of the calculator 13.
On the other hand, the deviation e input to the function generator 12 generates a speed difference command value V _r according to a predetermined characteristic, and is input to the + side input of the calculator 13. A well-known one having the following relational expression is used as the function generator. Example 1. A linear function that does not include saturation in the higher derivative, simply proportional to the position deviation, V _r = K _v * e ^1/1 K
_v is called a velocity deviation constant, and is the most general function used for exponential convergence of time.

Example 2. Non-linear function V _r = (2 * a) ^1/2 * e ^1/2 a including the second derivative with respect to position deviation and saturation of acceleration
Is the parameter of acceleration, the well known square root function used for "constant acceleration" convergence.

The output of the calculator 13 that calculates the difference between the two signals V _d and V _r is input to the operational amplifier 14. The output of the operational amplifier 14 becomes a command current for the armature circuit of the DC motor 4 via the motor driver 3. A pulse output proportional to the rotation speed of the DC motor 4 is obtained by the encoder 5. This output has a frequency of ₀ representing the actual number of revolutions of the motor.

In such a circuit configuration, the deviation e obtained by the difference counter 1 and further analog-converted by the D / A converter 2 is input to the differentiator 11 and the function generator 12. The differentiator 11 and the function generator 12 generate a speed difference detection value V _d and a speed difference command value V _r , respectively. Then, D is adjusted so that the difference between these two signals V _d and V _r becomes zero.
The C motor 4 is driven. Therefore, since the rotational position of the DC motor 4 is subtracted by the difference counter 1 for each pulse, the speed and the position of the DC motor 4 are only within the range of ± 1 pulse in the steady state due to the function of the integral element of the PI amplifier. The high gain control peculiar to the PLL that does not occur is performed. Furthermore, since the output frequency for the rotational positioning of the DC motor 4 is quickly converged, the time loss is greatly reduced. Further, since the signal source of the speed difference is taken directly from the position deviation signal e, a simple and accurate speed deviation signal can be obtained.

FIG. 2 is a block diagram showing an embodiment of a motor control device according to the present invention based on the block diagram of FIG.
This block diagram is obtained by adding a circuit to the block diagram shown in FIG. 1 to prevent overshoot that occurs when the output frequency reaches near the command speed and the command position. This circuit is the second arithmetic unit 1
5, the integral short-circuit condition group setter 16, the switch mechanism 17, and the like.

The circuit added here presets a condition for preventing overshoot after frequency pull-in, and sets this value, the position deviation signal e output from the D / A converter 2, and the speed difference detection. The value V _d and the integrator short-circuit condition setting value are calculated by the calculator 15 and output. The output thus obtained closes the switch mechanism 17 and shorts the integrating capacitor C in parallel with the operational amplifier 14.

As a result, the operational amplifier 14 has its original PI (proportional integral).
The characteristic is switched to the P (proportional) characteristic. Therefore, the overshoot of the position deviation due to the calculation component accumulated in the integrating capacitor is reliably prevented. In addition,
Although the switch mechanism 17 for short-circuiting the integrating capacitor C is used in FIG. 2, in addition to this, the voltage of the integrating capacitor C is promptly set to zero or a predetermined value by a signal obtained by amplifying the output of the calculator 15. A renewable analog hold circuit or digital sample / hold circuit can be used. It is also possible to employ an initial value updating circuit that performs presetting by a microcomputer.

According to the present invention, the output of the D / A converter is input to the differentiator and the function generator, respectively, and the rotation of the DC motor is controlled by the output of the calculator that inputs and outputs these outputs. In such control, speed difference (ΔV),
It is to detect whether or not a predetermined condition on the phase difference (Δφ) plane is satisfied. Therefore, the frequency can be pulled in quickly and accurately, position overshoot can be prevented, and accurate digital positioning of the motor can be achieved.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of a control device which is the basis of the present invention. FIG. 2 is a block diagram showing an embodiment of the present invention. Correspondence between the main reference symbols in the figure is as follows. 1: Difference counter 2: D / A converter 3: Motor driver 4: DC motor 5: Pulse encoder 11: Differentiator 12: Function generator 13: Arithmetic unit 14: Working amplifier 15: Second arithmetic unit 16: Integral short circuit Condition group setter 17: Switch mechanism

Continuation of the front page (56) Reference JP-A-55-127615 (JP, A) JP-A-54-30384 (JP, A) JP-A-55-29227 (JP, A) Actual development Sho-55-109396 (JP , U) Actual Development Sho 55-32663 (JP, U) Japanese Patent Sho 46-15364 (JP, B1)

Claims (1)

[Claims] 1. A difference counter for generating a cumulative value according to a speed difference and a position difference which are differences between a speed and a position as command values and an actual speed and a position, and a digital-analog conversion of an output of the difference counter. D / A converter, a differentiator for obtaining the speed difference detection value V _d from the output of the D / A converter, and a function generation for outputting the speed difference command value V _r from the output of the D / A converter , A calculator for calculating the difference between the outputs of the differentiator and the function generator, a motor driver for obtaining an output suitable for driving a motor corresponding to the output of the calculator, and the calculator In a motor control device including a working amplifier (PI amplifier) provided between the motor driver and the motor driver and having proportional and integral elements, a difference between a command value speed and an actual speed (speed difference ΔV ) And a detection means (15) for detecting whether or not a predetermined condition on the ΔV, Δφ plane, which is a combination of the command value and the actual position (phase difference Δφ), is satisfied, and the predetermined condition is satisfied. A means (17) for rapidly updating the voltage across the integrating capacitor (C) connected in parallel to the operational amplifier to zero or a predetermined value according to the output of the detecting means (15). A characteristic motor control device.