JPS61124284A - Speed controller - Google Patents

Abstract

PURPOSE:To enhance the transient response of a motor by correcting the later integrated value by the integrated value from when the speed deviation becomes zero at the first time to the time when the speed deviation becomes zero at the second time. CONSTITUTION:A speed deviation DELTAVn between a speed command Va and a speed feedback Vf is calculated by a proportional calculator 8, a differentiator 10 and an integrator 13. An integrating term A is stored from the time t1 when the speed deviation DELTAVn becomes zero at the first time at starting time to the time t2 when the speed deviation DELTAVn becomes zero at the second time. After the time t2, the product of the stored term A, the speed command value Va and the function F of the speed deviation DELTAVn is calculated, and the product of the integrated term after t2, the integrated term A and the function F, is added to integrate. Thus, the responding characteristics of the speed control system is improved to shorten the arranging time.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a motor speed control device.

Configuration of the conventional example and its problems As a conventional motor speed control device, as shown in FIG. 1, the specific configuration is shown in FIG. a speed detector 7 that digitally detects the speed, a speed feedback value vf2 that is the output of the speed detection booklet, a subtractor 3 that receives the speed command value va1 and the speed feedback value vf2 as inputs, and the subtracter 3. Input the output of proportional, integral,
It is composed of an arithmetic unit 4 that performs differential calculations, an amplifier 5 that amplifies the output of the arithmetic unit 4, and a motor 6 driven by the output of the amplifier 5. , 7, 2, the subtracter 3 and the arithmetic unit 4 are controlled by a microcomputer. FIG. 2 shows a specific configuration of the conventional arithmetic unit 4. As shown in FIG. In FIG. 2, 8 is a proportional calculation section, 9 is an integral calculation section, 10 is a differential calculation section, 11 is an adder, and 12 is a D/A converter. An example of the operation of a conventional motor speed control device will be explained below.

A conventional digital speed control device for a motor provides a speed command value va1 as a digital number, detects the speed of the motor 6 as a digital number in a speed detector 7, returns it as a speed feedback value vf2 to a subtracter 3, , the speed deviation between the speed command value v & 1 and the speed feed bank value vf2 is taken, and the speed deviation is input to the calculator 4, which operates a proportional calculation section 8, an integral calculation section 9, and a differential calculation section 1.
0 is calculated and input to the adder 11, and the adder 11
The output of is converted into an analog signal through the D/A converter 12, the analog signal is amplified by the amplifier 6, and the output of the amplifier 6 drives the motor 6, thereby forming a speed feedback system and setting the speed command value va1. This is to obtain a speed that follows.

The speed detector converts the two-phase rectangular wave signal from the position detector directly connected to the motor into a complete pulse train with a 90 degree phase difference, and counts the pulse train for a certain period of time using a counter. Speed is detected digitally.

The arithmetic unit 4 uses equation (1) to calculate proportional, integral,
Performing differential calculations.

5n=Kp(van-vfn+'s (vak u
lk) + Kd(Z'fn-I Z', (n)
−・−−−−−−−−−−・−(1) Here, S2 command signal? ,7. : Speed command value.

vf: velocity feedback value, Kp: proportionality constant.

K: Integral constant, Kd: Differential constant.

In equation (1), the first term is a proportional term and the second term is an integral term.

The third term is a differential term. The proportional term is for creating motor torque, the integral term is for zeroing out the steady deviation of speed with respect to the speed command value, and the differential term is for suppressing fluctuations in motor speed. In a digital speed control device, in a transient state, the integral calculation value is added to the speed command value va until the motor reaches the speed for the first time, so it becomes a very large value and deteriorates the responsiveness of the system. It is controlled to a certain level. FIG. 3 shows a block diagram of the speed control device shown in FIG. 1.

The transfer function of the motor system becomes as shown in equation (2) when the mechanical time constant is much larger than the electrical time constant of the motor.

Here, Z'm is the speed of the motor, i: the input of the motor, τE: the electrical time constant of the motor, τM: the mechanical time constant of the motor, and KE: the induced voltage constant.

In Figure 4, rH = 0.6ms, τM = 60nil
The characteristics of the case are shown below. (1), the integral constant Ki
Depending on the size of the speed control system, the speed control system may become oscillatory or take time to stabilize. Figure 4 shows a case where the integral constant has a relatively large force (Kp=256., =30°KD=
0.7) When a=1640 O), Figure 4 shows the case where the integral constant is small (Kp: 256, K, = 3゜Kp)
=O, υ, : 1640).

Since the motor system is a system with a near first-order lag, as shown above, the speed feedback system overshoots the speed command value and has the disadvantage that it takes time for the speed deviation to fall within a certain value. Was.

Purpose of the Invention In view of the above-mentioned drawbacks, the present invention eliminates the drawback of conventional motor speed control devices that it takes a long time to stabilize the system in a transient state, and provides a speed control device that can be started stably and in a short time. A control device is provided.

Structure of the Invention The present invention provides a computing unit that performs proportional, integral, and differential calculations based on a speed deviation between a speed command value that commands the speed of a motor and a velocity feedback value from the motor; It is composed of an amplifier for amplification, a motor driven by the output of the amplifier, and a speed detector for digitally detecting the speed of the motor, and the speed command is first detected in the arithmetic unit upon startup. The integral calculation value from the time when the speed deviation between the value and the speed feedback value becomes zero to the time when the one speed difference becomes zero is stored on the second side, and the second time when the speed deviation becomes zero. In the operation of the motor from the time when It has a unique effect.

Description of examples An embodiment of the present invention will be described below with reference to the drawings.

The configuration of this embodiment is generally shown in FIG. FIG. 6 shows a specific configuration inside the arithmetic unit in the embodiment of the present invention. The integral calculation will be explained below. In Fig. 4, the first speed command value and the speed feedback value t are
) f coincides with each other is tl, and the second time when the speed command value va and velocity feedback value vf coincide with each other is tl.
Set it to 2. The integral calculation is performed as shown in equation (2).

When the time is t and tl, the integral calculation is performed by integrating the product of the integral constant and the velocity deviation, and the maximum value is set to a certain constant value SKi max
1 and try to reduce the amount of overshoot. When the time is 1 (1 - 12), the calculation of the integral is the same as in the case of t - tl, but at t - t - t2, the speed deviation is small, so the maximum control value is set as SKim□2, and SKi
The value is set to be larger than ma. Furthermore, tl<t
Store the integral term A between <t2, and after 12<1, store the stored integral term A based on the stored integral term
The product of the speed command value and the speed deviation function F is calculated, and the integral term of t<t2 is ignored, and the value of the product of the integral term A and the function F is added to the integral term after t2. In other words, an integral operation is performed. In order to operate the motor stably at a constant speed with less speed deviation, a constant command value is required. The integral term A is used to generate a command signal necessary for rotating the motor at a constant speed in a shorter time than in the conventional method.

An example of the function F is shown in FIG. FIG. 7 shows the initial characteristics of such a speed control device using the same constants as in the conventional example. It can be seen that the response characteristics are improved and the settling time is extremely short compared to the conventional example shown in FIG. As can be seen from FIG. 7, the command value changes rapidly after time t2 compared to the conventional example. This rapid change makes the system stable in a shorter time than in conventional systems. In addition, Fig. 7a shows Kp: 256, Ki=30, KD
=o, 6:1640, and Figure 7 shows Kp=256
．． ,=3, KD=O,'1)a-=1640
Te1).

As described above, by using the integral value of the first overshoot region in the integral calculation and correcting the subsequent integral values by the product of the integral value, the speed command value, and the speed deviation function, the response characteristics of the speed control system can be improved. This has the effect of improving the stability and shortening the settling time.

It goes without saying that the proportional, integral, and differential calculations of the present invention can be used for controls other than motor speed control.

Effects of the Invention As described above, the present invention stores the integral calculation value of the first overshoot region in the integral calculation, and corrects the subsequent integral calculations by multiplying the stored calculation value and the function of the speed command value and speed deviation. By doing so, the response characteristics of the speed control system can be improved and the settling time can be made much shorter than before, and the practical effects of this are significant.

[Brief explanation of drawings]

Figure 1 is a configuration diagram of the basic Tanabata speed control device, Figure 2
Figure 3 is a block diagram of a basic motor speed control system, Figure 4 a and b are characteristic diagrams of a conventional motor speed control system, and Figure 5 is a diagram of a conventional motor speed control system. FIG. 6 is a correction function diagram, and FIGS. 7a and 7b are characteristic diagrams of a motor speed control system in an embodiment of the invention. 3...Subtractor, 4...Arithmetic unit, 5...
...Amplifier, 6...Motor, 7...Speed detector, 8...Proportional calculation unit, 10...
- Differential calculation section, 13... Integral calculation section. Figure 1 Figure 3 Figure 4 (aJ Figure 5 Figure 6 1iIk7 Figure fcl, 1

Claims (1)

[Claims] A calculator that creates a command signal by performing proportional, integral, and differential calculations based on the speed deviation between the speed command value that commands the motor speed and the speed feedback value from the motor, and inputs the output of the calculator. an amplifier for amplifying the signal;
In a digital speed control device comprising a motor driven by the output of the amplifier, the first
First, the integral calculation value from the time when the speed deviation between the speed command value and the speed feedback value becomes zero to the second time when the speed deviation becomes zero is stored, and secondly, the speed Motor speed control in which the integral calculation value in the computing unit is corrected by the product of the stored integral calculation value, the speed command value, and the function of the speed deviation in the operation of the motor after the deviation becomes zero. Device.