JPS62210502A - Controller multiplexing system - Google Patents

Abstract

PURPOSE:To prevent a shock to a controlled system even if an amplifier of a controller has the integrating function, by connecting outputs of plural controllers in parallel to the controlled system and selecting an intermediate value of multiplexed feedback signals from the controlled system. CONSTITUTION:Set values of controllers 1A and 1B are multiplexed and gived from upper controllers 3A-3C, and feedback FB signals from the controlled system 2 are multiplexed and are given to controllers 1A and 1B through analog input devices 4A-4C. Intermediate values are selected from set values and FB signals by intermediate value selecting circuits 11 and 12 in controllers 1A and 1B, and deviations between set values and FB values are operated by adders 13, and deviation signals are inputted to an amplifier 15 with the integrating function. Thus, the same set values and FB values are obtained by controllers 1A and 1B not to give a shock signal to the controlled system.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention improves the reliability of control by using a multiplex system for a control device, especially a circuit that is built internally in a fail-safe manner in the output stage of the control device. This invention relates to a system that easily and reliably realizes multiplexing to improve performance.

[Conventional technology]

FIG. 2 is a schematic diagram showing a conventional example of a duplex system. As is clear from the figure, since control multiplexing is generally expensive and cannot be performed up to a large-scale operation end, the control device IA is installed in front of the operation end.

1B is provided. For example, when one controller is used, K is
Using an automatic tracking device (not shown), the control device 1B always follows one control device. If a failure occurs in one of the control devices in this state, a failure signal F issued from one control device is given to the switch 7, which causes a shockless switch from the control device 1tlA to IB, and the subsequent control is Device IBK: Therefore, it continues.

Solving the problem 1st time → The duplication method as described above has the following problems.

b) In general, it is not possible to completely detect a failure of a single control device or UIB. Therefore, even if one control device fails, the failure signal F may not be given to the switching device 7, and in this case, the system will go down.

(Example) There is a possibility that failures such as poor contact or non-operation may occur in the switching device 7 as well (system down).

c) There is a possibility that the automatic tracking device (not shown) may fail. If a switching command is issued in such a case, there will be a large shock to the control system, and there is a high possibility that the system will go down.

Therefore, the applicant proposed a system as shown in FIG. 6 (hereinafter also referred to as the proposed system).

This is an example where the control device is duplicated, and the output stage portion consisting of an amplifier 15, a contact 16, a resistor 17, a relay 18, etc. is mainly shown. This LIC
, the contact 16 is normally closed, and opens when a failure occurs and the relay 18 is operated, so that it has a so-called fail-seven configuration. In addition, by connecting the output of each control device at point P and connecting it to the controlled object 2, as long as all of the control devices are operating smoothly, each control device can control the controlled object in a shared manner, while the control device Either y
If a failure occurs, the remaining control devices take over the task, thereby easily and reliably performing multiplexing (duplexing).

[Problem that the invention seeks to solve]

The overlapping method is effective when the control device does not have an integral function, but when it does have the integral function, it has the following problems.

This point will be explained with reference to the time chart of FIG. That is, in FIG. 3, for example, the control devices IA, IB
The set values (target values) for both are 5■, the feedback signal of one control device is 4.9V, and that of control device 1B is 5.1V (the difference in this feedback signal is due to the analog/digital (A/D) not shown in the figure). (D) due to errors in the converter, etc.), even if the output voltage E is 5■, which is the set value, the amplifier 15 (with an integral function) of the control device fiilA will be as shown in Fig. 4. While the amplifier 15 having an integral function of the control device 1B outputs a down signal as shown by the dotted line ■ in FIG. 4, this state continues. Therefore, one controller is the limiter for two amplifiers.

The outputs are increased in opposite polar directions as shown in FIG. 4 until the voltage (10 V in this case) is reached. After the control device 1A reaches the limiter voltage, the control device 1B controls the potential E at the connection point P to be equal to the set voltage. In this state, if one control device fails, for example, the contact 16 of the relay 18 in FIG. 5 opens. Based on this K, the control device 1B tries to control the potential at the connection point P to be equal to the set value, but since the amplifier has an integration function, the potential at the P point returns to the original voltage (5
It takes the time shown by T in FIG. 4 until recovery to v), and as a result, a shock signal as shown in FIG. 4 is given to the controlled object 2IIr. In addition, ■ in Figure 4
represents the potential at the connection point P in FIG.

Therefore, in this invention, the amplifier of the control device has an integral function (
It is an object of the present invention to provide a multiplex system of control devices that does not give the above-mentioned shock signal to a controlled object even when the control device has four nodes (I, PI, PIDy).

[Means for solving problems]

While each control device has a fail-safe configuration, its output sides are connected in parallel to each other and connected to the controlled object, and at least the feedback signal from the controlled object is multiplexed and sent to multiple devices via a common bus. The signal is applied to an intermediate value selection circuit provided in each control device, and the intermediate value is selected and used as a feedback signal.

[Effect]

The inconvenience pointed out in the previous problem is caused by the fact that the respective feedback signals of the control device take different values. Therefore, in the present invention, by providing an intermediate value selection circuit, it is possible to always make them match. Make it.

〔Example〕

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

In the same figure, IA and IB are control devices, 2 is a controlled object,
38 to 6C are upper control devices, 4A to 4C are analog input devices (Ai), 5 is a common bus, and 6A.

6B is an analog output device (Ao), 11.12 is an intermediate value selection circuit (MVG), 15 is an adder, 15 is an amplifier, 1
6 is a contact, 17 is a resistor, and 18 is a relay.

The set values (target values) of the control devices IA and IB are multiplexed (triplexed) and given via the common bus 5 from the higher level control devices 3A to 3C. On the other hand, feedback signals from the controlled object 2 are also multiplexed (tripled) and sent to each control device IA through the analog input devices 4A to 4C and the common bus 5.
, 1BK is given. In the control devices IA and IB, respective intermediate values are selected by intermediate value selection circuits 11.12 from among these triplicated set values and feedback signals. Then, the adder 13 calculates the deviation between this set value and the feedback value, and inputs this deviation signal to the amplifier 15 with an integral function.

As a result, exactly the same set value and feedback value are obtained in the control devices IA and 1B,
The problem pointed out earlier will be resolved. Note that the operations other than those described above are the same as those shown in FIG. 3, and will therefore be omitted. Further, although the common bus 5 shown in FIG. 1 has a very simple structure, if a failure of this common bus is assumed, it may be possible to make it redundant as shown by the dotted line in the same figure.

〔Effect of the invention〕

According to this invention, each of the control devices has a 7-kiel-safe configuration, and these are connected in parallel to each other, and by simply multiplexing at least the feedback signals and selecting and using the intermediate value, it is easy and reliable. This brings about the advantage that multiplexing of control devices can be realized. Such a system is effective and economical when applied to a case where a large number of final stages of a control system exist in parallel, such as an opening control system for a steam turbine control valve. Furthermore, since the control device can be duplicated instead of tripling the set values and feedback signals, it can be expected that the configuration will be simplified by this.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is a schematic diagram showing a conventional example of a duplex system, Fig. 3 is a block diagram showing a proposed system, and Fig. 4 is a problem with the problem shown in Fig. 3. It is a time chart for explaining. Code Description IA, IB... Control device, 2... Controlled object, 5A to 6C... Upper control device, 4A to 4
C... Song analog input device (Ai), 5... Common bus, 6A, 6B... Analog output device (A
o), 7...Switcher, 11.12...
Intermediate value selection circuit (MVG), 13...adder,
15...Amplifier, 16...Relay contact, 17...Resistor, 18.Song/Relay. Agent Patent Attorney Akio Namiki Agent Patent Attorney Kiyota Matsuzaki Figure 2 Figure 3

Claims (1)

[Claims] A multiplex system of control devices comprising a plurality of control devices that perform predetermined control, each of which has a fail-safe configuration, and whose output sides are connected in parallel with each other. At the same time, at least the feedback signal from the controlled object is multiplexed, and this is applied via a common bus to an intermediate value selection circuit provided in each of the plurality of control devices, and the intermediate value is A control device multiplexing system characterized by selective use.