JPS63124103A - Feedback control circuit - Google Patents

Abstract

PURPOSE:To obtain the satisfactory feedback characteristics without using any high-performance equipment by detecting the state of one of drive circuits that drive objects and controlling other drive circuits so that said state detection value is kept at a fixed level. CONSTITUTION:The state of a drive circuit 3 is detected by a detecting circuit 6 and a 2nd differential amplifier 7 outputs the control output so that the detection value of the circuit 6 is set closer to the set level of a target value setting circuit 8. Thus a 2nd drive circuit 9 undergoes feedback control. As a result, a part having a high response speed is controlled by the circuit 3 and a part having a low response speed and a large movement is controlled by the circuit 9 in terms of the overall characteristics of a feedback control circuit. Thus it is possible to obtain the satisfactory feedback characteristics with no use of a high-performance equipment.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a configuration of a feedback circuit of a feedback control circuit.

(Summary) In order to keep the output of a detection circuit that detects the state of an object in a constant state, the present invention provides a second feedback control circuit that controls a drive circuit of the object to detect the state of the drive circuit. By providing a detection circuit and a second drive circuit that drives the object, and controlling the second drive circuit to keep the output of the second detection circuit at a constant value, it is possible to eliminate the need for highly accurate equipment. This allows for good control.

[Conventional technology]

The conventional feedback control circuit is as shown in Figure 5.
When the state of object 1 changes due to external disturbance,
The differential amplifier 4
A method is adopted in which the drive circuit 3 is controlled to change the state of the object l.

In this case, in order for the characteristics of the drive circuit 3 to be able to respond to any external disturbances applied to the object 1, a highly accurate and high-performance device is required.

[Problem that the invention seeks to solve]

However, if such high-performance equipment is not available, the characteristics of the feedback control circuit deteriorate.

An object of the present invention is to solve this drawback and provide a feedbank control circuit that can obtain good feedback characteristics without using high-performance equipment.

[Means for solving problems]

The present invention includes a detection circuit that detects the state of an object, a drive circuit that changes the state of the object, and a control means that controls the drive circuit so that the detection output of the detection circuit is maintained at a constant value. A feedback control circuit comprising: a second detection circuit that detects the state of the drive circuit; a second drive circuit that changes the state of the object separately from the drive circuit; The present invention is characterized by comprising second control means for controlling the second drive circuit so as to maintain the detection output of the circuit at a constant value.

[For production]

A target object is driven using two or more drive circuits.

At this time, by detecting the state of one drive circuit and controlling the other drive circuits so that this test value is kept within a certain range, the deficiencies in the characteristics of each drive circuit can be complemented. I can do it.

〔Example〕

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

FIG. 1 is a block diagram of a first embodiment of the present invention.

In FIG. 1, the feedback control circuit includes a detection circuit 2 that detects the state of the object 1, a drive circuit 3 that changes the state of the object 1, a differential amplifier 4, and a target value setting circuit 5.
It is composed of

The differential amplifier 4 controls the drive circuit 3 so that the detection output of the detection circuit 2 becomes a constant value set in the target value setting circuit 5.

The object 1 here is a variable gain amplifier, the detection circuit 2 is a circuit for detecting its output level, and the drive circuit 3
is a control circuit that controls this gain. The reference gain of this amplifier is given to the target value setting circuit 5.

The features of the present invention are that the feedback control circuit includes a second detection circuit 6 that detects the state of the drive circuit 3, and that the detection output is set to a constant value set in the target value setting circuit 8. The second drive circuit 9 is controlled by the differential amplifier 7 and drives the object 1.

In FIG. 1, the drive circuit 3 has a sufficiently fast response speed but a narrow operating range. The second drive circuit 9 has a slow response speed but a wide operating range.

The state of the drive circuit 3 is detected by the detection circuit 6. The 20th differential amplifier 7 sends out a control output so that this detected value approaches the set value of the target value setting circuit 8.

As a result, the second drive circuit 9 is feedback-controlled. As a result, the characteristics of the feedback control circuit as a whole are such that the portion with a fast response speed is controlled by the drive circuit 3, and the portion with a slow response speed but large is controlled by the drive circuit 9. This allows the characteristics of feedback control to be significantly improved. This improvement effect will be explained using FIG. 2. FIG. 2(a) shows a waveform of a change in the state of the object, and the operating range of the drive circuit 3 is within the values of +α and -α indicated by the - dotted chain line. When feedback control is performed with the configuration shown in Fig. 1, the low frequency component of the fluctuation shown in Fig. 2 (a) becomes as shown in Fig. 2 (C1). , the operation of the drive circuit 3 is as shown in FIG. 2(b).
Only the high frequency components need be compensated.

Therefore, its operating range can be as narrow as +β and -β.

Furthermore, when the drive circuit 3 sends out a voltage signal as a control output, the detection circuit 6 is configured to detect a divided voltage of this voltage signal. In this way, the detection circuit 6 does not directly detect the characteristics of the object 1, and the configuration of the detection circuit 6 becomes extremely simple.

FIG. 3 is a block diagram of a second embodiment of the present invention. In this embodiment, the second detection circuit is activated by determining the state of the drive circuit 3 by determining the signal input to the drive circuit 3. This is a simplified version.

FIG. 4 shows the operating characteristics of the second embodiment. In Fig. 4, the state of the drive circuit 3 is set within a preset range (Fig. 4C).
The drive circuit 9 in FIG. 3 operates so as to be controlled to the inside of the − dotted line +α and −α of a>. In this case, the operations of drive circuits 3 and 9 are respectively
).

The circuit that performs the operation shown in FIG. 4 has almost the same configuration as that shown in FIG. 1. In this case, the operation of the target value setting circuit 8 and the differential amplifier 7 may be performed by digital processing using a microprocessor instead of by a single element.

As described above, in each of the embodiments shown in FIGS. 1 and 3 of the present invention, two sets of drive circuits have been described, but the state of the second drive circuit 9 may be compensated for by another drive circuit, etc. , it is also possible to increase the number of drive circuits and improve the feedback control characteristics. In this case, the operating characteristics of the plurality of drive circuits can be those of the method shown in FIG. 2, those of the method shown in FIG. 4, or a combination of both.

〔Effect of the invention〕

As explained above, according to the present invention, there is an effect that a feedback control circuit with good characteristics can be realized without using highly accurate and expensive equipment.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a first embodiment of the present invention. FIG. 2 is a characteristic diagram illustrating the operation of the above embodiment. FIG. 3 is a block diagram of a second embodiment of the present invention. FIG. 4 is a characteristic diagram illustrating the operation of the above embodiment. FIG. 5 is a block diagram of a conventional example. 1...Target, 2.6...Detection circuit, 3.9...
Drive circuit, 4.7... Differential amplifier, 5.8... Target value setting circuit, ±α, ±β... Range limit value. Block configuration diagram of the first embodiment Figure 1 (b) (C) Characteristic diagram of the first embodiment Figure 2 Block configuration diagram of the second embodiment Figure 3 (b) (C) Characteristic diagram of the second embodiment Figure 4 Block configuration diagram of conventional example Figure 5

Claims (1)

[Claims] (1) A detection circuit that detects the state of the object, a drive circuit that changes the state of the object, and a control means that controls the drive circuit so that the detection output of the detection circuit is maintained at a constant value. A feedback control circuit comprising: a second detection circuit that detects the state of the drive circuit; a second drive circuit that changes the state of the object separately from the drive circuit; and a second detection circuit that changes the state of the object. and second control means for controlling the second drive circuit so as to maintain the detected output at a constant value.