JPH0191694A - Controller for ac motor - Google Patents

Abstract

PURPOSE:To prevent a system from being spoiled due to a transient fault and improve the reliability of the system extremely, by operating a controller continu ously till the same sort of fault factors are detected by specified frequency with a fault discriminating circuit. CONSTITUTION:When a fault is generated in a controlling circuit 22 at a time (t1), then the fault is detected by an operating circuit 221, and via an operating circuit 231, from a time (t2), a controlling circuit 23 is operated. The input of a fault factor generated at the time (t1), to a fault discriminating circuit 222 is provided, and the factor is compared with a stored and formerly generat ed fault factor, and it is discriminated whether the fault factors are the same sort of ones or not. Even if the fault factors are the same sort of ones, if they are generated by specified frequency or less, the operation of a controller is re-started by the controlling circuit 23 from the time (t2).

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Field of Application) The present invention relates to a separate AC electric control device, and in particular, to improve system reliability by making at least a part of the control circuit of the control device redundant. The invention relates to an AC-ON control device.

(Prior Art) As a control device for an AC motor according to the present invention, various systems such as a current source inverter device, a thyristor motor device, and a cycloconverter device have been put into practical use. Here, the conventional technology will be explained below using a control device for an AC motor, in which a current source inverter device is cited as a representative example in FIG.

In FIG. 3, 10 is a main circuit of a control device for an AC motor, and as a concrete explanation of the main circuit, 11 is an input breaker;
12 is a rectifier, 13 is a DC reactor, and 14 is an inverter. 20 is a control circuit section of the control circuit for the AC motor, as well as a specific explanation of the control circuit section.
1 is a reference, 22 is a control circuit, 23 is a control circuit, 24 is a control circuit, 25 is a control circuit discrimination circuit, and 30 is an AC motor driven by the AC electric wave control device.

Regarding the basic operation of the AC type vJ compensation control device shown in Fig. 3, for example, "New Drive Elect 02" (
Published by Denkishoin, edited by Naohiko Ueyama) Chapter 4 1) 103-p1
44, so only the main points will be discussed here. In the main circuit 10, AC power input through a breaker 11 is converted into DC power by a rectifier 12, smoothed by a DC reactor 13, and converted into variable frequency AC power by an inverter 14, and then converted into AC power by an inverter 14. Type l]
Drive 30 losses. In the control circuit 20, based on the command given from the reference 21, the control circuits 22.
23 and 24 are provided, and these output signals are input to the control circuit discrimination circuit 25, and three control circuits 22, 23, and 24 are provided.
A control circuit discriminating circuit 25 discriminates the output of
The determined normal control output signal is given to the main circuit 10, and the AC power eF! li30 is being driven.

As explained above, in the configuration shown in FIG. 3, a redundant system is provided in which a total of three sets of control circuits 22, 23, and 24 are provided, and the three sets of control circuits 22, 23, and 24 each output an output signal while being operated. The control circuits 22, 23.
It is well known that even if one of the sets fails, the system can continue operating, and by creating a redundant system in this way, system reliability is greatly improved.

Conventionally, in control devices for AC motors, there were few examples in which part of the control circuit was configured as a redundant system, but as the field of application expanded to important plants, there was a need to improve the system reliability of the - layer, and as a result, the third 2. Description of the Related Art Separate AC electric control devices have come to be manufactured in which at least a portion of the control circuit is configured redundantly as shown in the figure. Although the prior art has been explained with reference to typical examples of these systems in FIG. 3, there are various other systems. However, a common point in the prior art is that a circuit corresponding to the function of the control circuit discrimination circuit 25 is provided to discriminate and output control circuit output signals of a plurality of sets of control circuits.

(Problems to be Solved by the Invention) The AC motor control device based on the prior art shown in FIG. 3 has a control circuit determination circuit 25 in its control section 20. As a result, the following problems occurred.

(1) When the number of control circuit output signals of the control circuits 22, 23, and 24 increases as in a control device for an AC motor,
The need to judge each signal level makes the control circuit discrimination circuit complex, and as a result, the number of components in the control circuit discrimination circuit increases significantly, and the overall reliability of the control circuit section 2o is not expected to improve. There is a problem that the value does not improve.

(2) From the above point, the problem of increasing the size of the control circuit section 20 and increasing the price occurs in the control of AC type e-controllers.

(3) Since a plurality of sets of control circuits 22, 23, and 24 are operated or are operated in standby mode, there is a problem that the power loss of the control circuits also increases.

(4) In conventional systems, once a failure is detected, the system stops, but depending on the cause of the failure, some systems may be able to continue operating, so a means to prevent the system from stopping is required, especially for loads with special characteristics.

The present invention has been developed in view of the drawbacks of the prior art described above, and is a control device for an AC motor.
An object of the present invention is to provide a control device for an AC motor that improves reliability as a redundant system by not providing a discrimination circuit for identifying the output state of the redundant component in the latter stage of the redundant component when the component is configured as a redundant system. The purpose is

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above-mentioned object, the present invention provides a redundant system configuration in which at least a part of the control circuit constituting the control device for an AC motor is composed of at least two sets of circuits. and a means for selecting one of the control circuits configured as a redundant system to control the AC electric motor; and, when the selected control circuit fails, control for the failed control circuit to be on standby; A control circuit discriminating circuit as in the prior art is provided with means for repeating the switching operation to the circuit, and means for determining that the same type of failure has occurred a predetermined number of times or more during this repeated operation and stopping the operation of the control device. (corresponding to 25 in Fig. 3), the system configuration is such that the redundant system configuration is simplified and the system reliability is improved overall. It is something.

(Function) In the control device of the AC/N moving rock configured in this way, if one of the control circuits 22 and 23 has a redundant system configuration and the control device malfunctions due to an abnormality or other factors, switching to the other control device occurs. At this time, there occurs a period in which the output of the control circuit section 20 is instantaneously stopped.

As a result, the output of the main circuit 10 of the AC motor brake W device also stops instantaneously, but the AC motor 3 that is being driven
0 and its load have inertia, and if the output is stopped for such a short time, the rotational speed may fluctuate but it will not stop. Therefore, the control circuits 22 and 23 are mutually switched. There will be no system outage.

In addition, it is very difficult to determine whether the cause of the failure of the control device a is caused only by the control circuit 22 or 23, and some causes of failure are temporary, so failures of the same type If the failure determination circuit 222 determines whether or not the error has occurred a predetermined number of times, and if not, the control device continues to operate, it is possible to significantly prevent a system down due to a temporary cause of failure.

The present invention focuses on the fact that the control device for an AC motor is an AC motor with inertia, and has simplified and improved reliability as a technology unique to devices that drive loads with inertia. This is to realize a highly reliable AC power fj11 control m+ device that applies the redundant system of the control circuit section.

(Example) The present invention will be described in detail below based on the example shown in the drawings.

FIG. 1 shows a control device for an AC motor showing an embodiment of the present invention. In this figure, the components labeled with the same numbers as in FIG. 3 of the prior art are the same or different components,
Omit explanation. Further, a driving operation circuit 221, a part of which is included in the control circuit 22. Similarly, the driving operation circuit 2 for the control circuit 23
31 in particular to make it easier to understand the effect of the present invention.
Illustrated in addition to the figure. Furthermore, a failure determination circuit 222 that determines the failure status of the control circuits 22 and 23 is shown.

In FIG. 1, inside the control circuit unit 20, one of the control circuits 22 and 23 configured as a redundant system is used during operation of an AC electric type control device, and the other control circuit 2
2 or 23 is the driving operation circuit 2 in a standby state.
Control circuits 22 and 23 are controlled by 21 and 231. If a failure occurs in the control circuit 22 or 23 during operation in such a state, or if a failure occurs in the control device, this is detected by the operation operation circuit 221 or 231, and the control circuit 22 or 23 during operation is detected. The other control circuit 22 or 23 is started via the other operation operation circuit 221 or 231. At this time, the failure determination circuit 222 stores the cause of the failure that has occurred, and similarly, when the next failure occurs, it determines whether the failure is due to a similar failure cause.

FIG. 2 illustrates this mode of operation. In Figure 2,
(A> is the output of the main circuit 10 of the control circuit 10 of the AC motor, <8) is the output IMJ l signal of the control circuit 22, (
C) shows the output control signal of the control circuit 23, and the control circuit 22 is operated until time t1, but if a failure occurs in the control device operating in the control circuit 22 at time t1, the control circuit 22 is operated until time t1. is detected by the driving operation circuit 221, and the control circuit 23 is operated from time t2 via the driving operation circuit 231.

The cause of the failure that occurred in 1 at this time is the failure determination circuit 222.
It is input to the controller and compared with the previously stored failure cause to determine whether the failure is of the same type. Resume operation of the control device.

As a result, the output of the main circuit 10 that is supplied to the AC motor 30 is interrupted for a short period of time from time t1 to time t2, but this period is generally short and the AC motor 1o and its load rotate due to inertia. Since the number fluctuation is small, the AC motor drive system can continue to operate.

Regarding the failure of the control device that occurred at time [3], the failure determination circuit 222 similarly operates separately and resumes operation from time t4.

As described above, since the control device continues to operate until the same type of failure cause is detected a predetermined number of times, it is possible to prevent the system from going down due to a temporary failure cause, and the system reliability can be greatly improved.

(Effects of the Embodiment) According to the embodiment of the present invention shown in FIG.
Even if one part of the control circuits 22 and 23 is configured as a redundant system, one of the control circuits 22 or 25 can be configured as a redundant system without providing a control circuit determination circuit having a complicated circuit configuration to determine whether the output control signal is good or not. Even if the system fails, the AC power-like control device can continue operating.

Furthermore, although it is generally difficult to classify and identify failures in control circuits, this is not necessary in the present invention (and there is no need to stop the control device of an AC generator due to a temporary failure factor).

Therefore, according to the present invention, an AC motor control device having a simple circuit configuration and high reliability can be realized.

The AC motor 1IIIIII2I device of the present invention is not particularly limited in its circuit system, and can be applied to various types of AC motor control devices as long as at least a part of its control circuit has a redundant system configuration. It is clear that it can be done.

In the AC motor control device of the present invention, only two control circuits are shown in the figure to constitute the redundant system, but the number of control circuits is not particularly limited.

In the AC motor control device of the present invention, when the other healthy control circuit starts operating at time t2 in FIG. 2, the AC motor 30 is operated with the induced voltage phase of the AC motor 30 close to the output voltage phase of the AC motor control device. You may start. By controlling in this way, the fluctuation in the rotational speed of the AC motor 30 can be further reduced.

[Effects of the Invention] According to the present invention, when a part of the control circuit of an AC motor control device is configured as a redundant system, the redundant system configuration is achieved by utilizing the inertia of the driven AC motor and its load. There is no need for a control circuit discriminating circuit for discriminating the quality of the output-control signal of each control circuit. As a result, according to the present invention, a control circuit for an AC motor having the following effects and advantages can be realized.

(1) Since there is no need for a control circuit discrimination circuit that requires a complicated circuit configuration even when the number of output control signals is large, the number of circuit components in the control circuit section is significantly reduced, simplifying the control circuit section and achieving high reliability. This makes it possible to realize a control system for AC I7J machines that is highly reliable overall.

(2) Even if the number of control circuits constituting the redundant system is the minimum, redundant operation can be performed in the same manner as in the conventional redundant system configuration, and since a control circuit discriminating circuit is not required, power loss in the control circuit is also small.

(3) Since the control circuit section can be simplified, a compact and low-cost AC motor control m+ device can be realized.

(4) Although it is very difficult to determine whether a failure has occurred in the control circuit part that constitutes the redundant system, this is not necessary in the present invention, and furthermore, the failure of the control device due to another temporary failure factor is stopped. can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a diagram showing an operation mode according to the actual flow example of the present invention shown in FIG. 1, and FIG. 3 is a block diagram of a control device for an AC motor according to the prior art. It is a diagram. 10... Main circuit of AC power vJ Iso control device, 11...
- Input breaker, 12... Rectifier, 13... DC reactor 1.14... Inverter, 20... Control circuit section of AC motor control TLL device, 21... Standard, 2
2...Control circuit, 23...Control circuit, 24...Control circuit, 221...Driving operation circuit, 222...Failure determination circuit, 231...Driving operation circuit.

Claims (1)

[Claims] In a control device for an AC motor that drives a load having inertia, at least a part of the control circuit constituting the control device is configured as a redundant system with at least two sets of circuits, and any one of the control circuits configured as a redundant system is configured. means for selecting one of the control circuits to control the AC motor; means for repeating switching operation to a control circuit on standby for the failed control circuit when the selected control circuit fails; and during this repeated operation; A control device for an AC motor, comprising means for determining that the same type of failure has occurred a predetermined number of times or more and stopping operation of the control device.