JP2000152488A - Load controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To downsize an AC input circuit, reduce cost and secure the reliability of the system, without installing a capacitor even in the case that a start operation switch and a stop operation switch are apart from a transformer for operation. SOLUTION: A logical operation circuit is composed of a microcomputer 40 and an auxiliary logical operation circuit 41 which is operated by clocks so as to disperse input and output functions, and this load controller is equipped with a pulse width detecting circuit 65 and a digital filter circuit 66 within the auxiliary logical operation circuit 41. A bidirectional photocoupler 62 outputs the pulse signal of fixed duty according to the input level, and transmits it to the next stage. Also, the pulse width detecting circuit 65 detects the voltage level from the duty of the pulse signal outputted from the bidirectional photocoupler 62 and judges that an AC input signal is on when it is not less than a certain preset voltage level, and the digital filter circuit 66 continues an ON signal during the preset time after the pulse width detecting circuit 65 detects the AC input signal being ON, and transmits it to a microcomputer 40 on the next stage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a load control device for controlling a main circuit device such as a motor for opening and closing a load by a logical operation circuit.

[0002]

2. Description of the Related Art A control center is known as an example of a load control device having an opening / closing control function and a protection function for a motor and a resistance load. That is, in the control center, a plurality of units are provided for each unit circuit, such as electromagnetic contactors, circuit breakers, current converters, and auxiliary control relays, and these units are arranged in multiple stages in the machine frame. It is housed and provided with an operating device including a start operation switch, a stop operation switch, and the like for each unit. FIG. 3 shows an example of the configuration of such a control center. That is, FIG. 3 schematically shows the circuit configuration of one unit of the control center. The main circuit 3 between the three-phase power supply bus 1 and the induction motor 2 as a load includes a circuit breaker for wiring. 4, an electromagnetic contactor 5, a current transformer 6 for detecting a main circuit current, and a zero-phase current transformer 7 for detecting a ground fault current. On the load side of the circuit breaker 4, one of the operation transformers 8 is connected.
The secondary winding 8a is connected, and the operation transformer 8
Control buses 9a and 9b are connected to the next winding 8b.

A control circuit unit 10 to which power is supplied from the control buses 9a and 9b through a DC power supply (not shown) is mainly composed of a logical operation circuit 11, and is connected between an output terminal 10a and the control bus 9a. In between, the electromagnetic contactor 5
Operation coil 5a is connected. A start operation switch 12, a stop operation switch 13, and a normally-open auxiliary contact 5b of the electromagnetic contactor 5 are connected between the input terminals 10b, 10c, 10d of the control circuit unit 10 and the control bus 9a. Is done. The control circuit unit 10 opens and closes the electromagnetic contactor 5 based on a start signal from the start operation switch 12, a stop signal from the stop operation switch 13, and an ON signal and an OFF signal from the auxiliary contact 5 b of the electromagnetic contactor 5. It has a function of performing control and performing protection operations such as overload, open phase, undercurrent, and ground fault based on current signals from the current transformer 6 and the zero-phase current transformer 7.

More specifically, in the control circuit unit 10, in addition to the logical operation circuit 11, the secondary side outputs of the current transformer 6 and the zero-phase current transformer 7 receive the main circuit current signal. A current detection circuit 14 for generating a load current detection signal indicating the level and a ground fault current detection signal indicating the level of the ground fault current; a setting switch 15 for setting protection operation conditions (protection operation current, protection operation time, etc.); A display circuit 16 for displaying the level of the load current, an abnormal state, etc., a drive circuit 17 for energizing the operating coil 5a of the electromagnetic contactor 5, a signal output circuit 18 for outputting the details of the abnormality to the outside, and the like are provided. It is comprised including. The logic operation circuit 11 is configured to operate based on operation signals from the operation switches 12 and 13, a detection signal from the current detection circuit 14, protection operation conditions set by the setting switch 15, and a program stored in advance. The control operation of the induction motor 2 as a load,
The protection operation against the occurrence of abnormalities such as overcurrent, open phase, and ground fault is performed through the drive circuit 17, and the operation of outputting the details of the abnormality to the outside through the signal output circuit 18 is performed.

In this case, it is general that the logic operation circuit 11 performs all the control using a microcomputer. In recent years, however, only a part of the control functions, for example, only the input / output control is performed by another IC. For example, a configuration in which an ASIC is assigned, that is, a system in which a system for performing distributed processing is constructed is also provided.

Here, the start signal from the start operation switch 12 and the stop signal from the stop operation switch 13 are transmitted to the control buses 9a, 9b connected to the secondary winding 8b of the transformer 8.
, And is an AC signal. Therefore, in the control circuit unit 10, unless the signal is converted into direct current, the processing by the logical operation circuit becomes difficult.
Therefore, the AC input circuit in the conventional control circuit unit 10 has a circuit configuration as shown in FIG.

FIG. 4 shows one circuit of the AC input circuit. In the figure, reference numeral 51 denotes a current limiting circuit composed of a resistor and a capacitor. Reference numeral 52 denotes a bidirectional photocoupler that insulates the AC input signal from the control circuit unit 10.
Reference numeral 53 denotes a bypass resistor for preventing the bidirectional photocoupler from operating until a current of a certain value or more flows in the circuit.
4 is a voltage detection resistor. Reference numeral 55 denotes a filter circuit configured by a resistor and a capacitor for smoothing a pulse signal of a full-wave rectified output current. When a start signal or a stop signal is turned on and a current flows through the circuit, the bidirectional photocoupler 52 The insulated full-wave rectified output current flows through the filter circuit 55, and the smoothed and DC-converted voltage is supplied to the auxiliary logic operation circuit 56 and the logic operation circuit (microcomputer) 57 at the next stage.
Was input and processed.

[0008]

In the case of the AC input circuit configured as described above, the filter circuit 55 generally requires a capacitor having a large capacity for current smoothing, and the circuit is large. In FIG. 3, only the start signal and the stop signal are A
Although the C input circuit is not described, it is difficult to downsize the circuit, that is, downsize the control circuit unit 10, particularly when a large number of AC input circuits for sequence are provided. In addition, when the start operation switch 12 and the stop operation switch 13 are separated from the operation transformer 8, the control cable becomes long, and for example, the stop operation cannot be performed due to the stray capacitance 50 between the cables. Therefore, in order to lower the impedance of the circuit, it is necessary to install a large-capacity capacitor 58 in parallel on the primary side of the bidirectional photocoupler 52.

An object of the present invention is to reduce the size of the AC input circuit, that is, to reduce the size of the control circuit unit 10, and even when the start operation switch 12 and the stop operation switch 13 are separated from the operation transformer 8. The object of the present invention is to reduce the cost without installing the capacitor 58 and to ensure the reliability of the system.

[0010]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a main circuit device such as an electromagnetic contactor interposed in a main circuit between a power supply bus and a load, and a device for operating the main circuit device. Operating device, detecting means for detecting main circuit current and the like, and controlling the main circuit device and the like based on an input signal from the operating device, a detection signal from the detecting means, and a program stored in advance through an external output circuit. In a load control device including a logical operation circuit, the load control device includes a microcomputer that functions as a main control circuit, and an auxiliary logical operation circuit that is operated by a clock to perform a distributed processing of input / output functions. And an AC input circuit for operating the main circuit device, wherein the AC input circuit is a current control system comprising a resistor and a capacitor. It consists of a circuit, a bidirectional photocoupler that insulates input signals, a bypass resistor and a voltage detection resistor that do not operate the bidirectional photocoupler until a current of a certain value or more flows in the circuit, and an auxiliary logic operation circuit. A pulse width detection circuit and a digital filter circuit are provided inside, and the bidirectional photocoupler performs full-wave rectification on the AC input signal from the AC input circuit, and outputs a pulse signal having a constant duty according to the input level. While transmitting to the next stage, the pulse width detection circuit inside the auxiliary logic operation circuit detects the voltage level from the duty of the pulse signal output from the bidirectional photocoupler, and detects a voltage level equal to or higher than a predetermined fixed voltage. When it is determined that the AC input signal is on, the digital filter circuit in the auxiliary logic operation circuit After Oite AC input signal has been detected on, it continued during ON signal for a preset time is obtained by a configuration as transmitting a next stage of the microcomputer. (Claim 1) According to such a configuration, the start signal from the start operation switch 12 and the stop signal from the stop operation switch 13 are transmitted to the AC input circuit, and the AC input circuit is composed of a resistor and a capacitor. The current is limited to a constant current by the current limiting circuit, and then transmitted to the bidirectional photocoupler.

Here, the bidirectional photocoupler performs full-wave rectification on the AC input signal from the AC input circuit, outputs a pulse signal having a constant duty according to the input level, transmits the pulse signal to the next stage, and outputs the auxiliary logic signal. The pulse width detection circuit inside the arithmetic circuit detects the voltage level from the duty of the pulse signal output from the bidirectional photocoupler, and determines that the AC input signal is on when the voltage is equal to or higher than a certain voltage. The digital filter circuit in the auxiliary logic operation circuit continues the on signal for a preset time after the pulse width detection circuit detects that the AC input signal is on, and transmits the signal to the next logic operation circuit. It has become.

Therefore, unlike the conventional AC input circuit,
A large current smoothing capacitor of the filter circuit 55 is not required, and the circuit can be downsized. Further, as in the invention according to claim 2, the auxiliary logic operation circuit is
The circuit can be further miniaturized if constituted by the SIC. Further, a start operation switch 12, a stop operation switch 1
When the control cable 3 is away from the operation transformer 8, the control cable may be long and a stray capacitance 50 between the cables may cause a stop operation, for example, to be impossible. In order to reduce the impedance of the circuit, It was necessary to install a large-capacity capacitor in parallel on the primary side of the bidirectional photocoupler. However, as described in claim 3, when the AC input signal of the internal pulse width detection circuit is turned on. If a certain voltage to be determined is appropriately adjusted and set, these also become unnecessary. Further, if the duration of the ON signal can be arbitrarily changed from outside by a digital filter circuit inside the ASIC, the repetitive input time interval of the input signal can be freely adjusted. Become.

According to a fifth aspect of the present invention, in a pulse width detection circuit in an ASIC, even if an input signal is discontinuous for a short time due to the influence of noise or the like, it is ignored and regarded as a continuous signal. Then, a load control device that is resistant to noise can be obtained.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a control center will be described below with reference to the drawings. FIG. 2 shows a circuit configuration of one unit of the control center. In this embodiment, the overall configuration is almost the same as that of the conventional example shown in FIG. That is, in FIG. 2, a main circuit 23 is formed between a three-phase power supply bus 21 and an induction motor 22 which is a load, and the main circuit 23 has a main circuit device wiring disconnection. A current transformer 26 for detecting a main circuit current, a zero-phase current transformer 27 for detecting a ground-fault current, and the like are connected to the switch 24 and the electromagnetic contactor 25.

A primary winding 28a of an operation transformer 28 is connected between the R phase and the T phase on the load side (power supply side of the electromagnetic contactor 25) of the circuit breaker 24 in the main circuit 23, Control buses 29 and 30 are connected to a secondary winding 28b of the operation transformer 28.

In this case, the output from between the control buses 29 and 30 is used as a power supply for the control circuit unit 31 via a DC power supply circuit (not shown). An operating coil 25a of the electromagnetic contactor 25 is connected between one control bus 29 and the output terminal 31a of the control circuit unit 31,
The control bus 29 and the input terminal 3 of the control circuit unit 31
A start operation switch 32 as an operation device, a stop operation switch 33 as an operation device, and a normally-open auxiliary contact 25b of the electromagnetic contactor 25 are connected between each of 1b, 31c and 31d.

The control circuit unit 31 controls the electromagnetic contactor 25 based on a start signal from the start operation switch 32, a stop signal from the stop operation switch 33, and an on signal and an off signal from the auxiliary contact 25b of the electromagnetic contactor 25. Is configured to perform a control operation of opening and closing the. The control circuit unit 31 includes a current transformer 26 and a zero-phase current transformer 27.
Overload, open phase, undercurrent,
It has a function of performing a protection operation against occurrence of an abnormality such as a ground fault and a function of performing an abnormality content output operation of outputting the details of the abnormality to the outside.

The control circuit unit 31 is mainly composed of a logical operation circuit 34.
6 and a secondary-side output of the zero-phase current transformer 27, a current detection circuit as a detection means for generating a load current detection signal indicating a main circuit current signal level and a ground fault current detection signal indicating a ground fault current level. 35, a setting switch 36 for setting protection operation conditions (protection operation current, protection operation time, etc.), a display circuit 37 for displaying the level of a load current and an abnormal state, etc., and an operation coil 25a of the electromagnetic contactor 25 And a drive circuit 38 (corresponding to an external output circuit according to the present invention) for supplying current to an external load, a signal output circuit 39 (corresponding to an external output circuit according to the present invention) for outputting the contents of an abnormality to the outside, and the like. It is comprised including.

FIG. 1 shows a specific configuration of the AC input circuit in the control circuit unit 31. This figure 1
, The logical operation circuit 34 includes a microcomputer 40 functioning as a main control circuit for performing the above-described control operation and protection operation, and an auxiliary logical operation circuit 41 for performing input / output control including the above-described abnormality content output operation. (The ASIC according to the present invention), and is configured to perform distributed processing.

Here, the AC input circuit includes a current limiting circuit 61 composed of a resistor and a capacitor, a bidirectional photocoupler 62 for insulating an input signal, and a bidirectional photocoupler until a current of a certain value or more flows through the circuit. , A bypass width resistor 63 and a voltage detection resistor 64 for preventing the operation of the circuit, and a pulse width detection circuit 65 and a digital filter circuit 66 are provided inside the auxiliary logic operation circuit 41.

Next, the operation of the embodiment constructed as described above will be described. The start signal from the start operation switch 32 and the stop signal from the stop operation switch 33 are A
The current is transmitted to the C input circuit, and after being limited to a constant current by the current limiting circuit 61 composed of a resistor and a capacitor in the AC input circuit, is transmitted to the bidirectional photocoupler 62. Here, the bidirectional photocoupler 62 is AC
The AC input signal from the input circuit is full-wave rectified, a pulse signal having a constant duty is output according to the input level and transmitted to the next stage, and the pulse width detection circuit inside the auxiliary logic operation circuit 41 The voltage level is detected from the duty of the pulse signal output from the directional photocoupler 62, and when the voltage is equal to or higher than a certain voltage, it is determined that the AC input signal is turned on. After the pulse width detection circuit 65 detects that the AC input signal is ON, the circuit 66 continues the ON signal for a preset time and transmits the ON signal to the microcomputer 40 at the next stage.

[0022]

As apparent from the above description, according to the first aspect of the present invention, the start signal from the start operation switch and the stop signal from the stop operation switch are transmitted to the AC input circuit, The current is limited to a constant current by a current limiting circuit composed of a resistor and a capacitor, and then transmitted to a bidirectional photocoupler.

Here, the bidirectional photocoupler performs full-wave rectification on the AC input signal from the AC input circuit, outputs a pulse signal having a constant duty in accordance with the input level, transmits the pulse signal to the next stage, and outputs the auxiliary logic signal. The pulse width detection circuit inside the arithmetic circuit detects the voltage level from the duty of the pulse signal output from the bidirectional photocoupler, and determines that the AC input signal is on when the voltage is equal to or higher than a certain voltage. The digital filter circuit in the auxiliary logic operation circuit continues the ON signal for a preset time after the pulse width detection circuit detects that the AC input signal is ON, and transmits the ON signal to the microcomputer of the next stage. Has become.

Therefore, unlike the conventional AC input circuit,
A large-capacity capacitor for the current smoothing of the filter circuit 54 is not required, and the circuit can be downsized. Further, as in the invention according to claim 2, the auxiliary logic operation circuit is
The circuit can be further reduced in size by using the SIC.

When the start operation switch 9 and the stop operation switch 10 are separated from the operation transformer 8, the control cable becomes long, and for example, the stop operation cannot be performed due to the stray capacitance between the cables. In order to reduce the impedance of the circuit, it is necessary to install a large-capacity capacitor on the primary side of the bidirectional photocoupler. If it is determined that the AC input signal of the detection circuit is on, a certain voltage is appropriately adjusted and set, or if the voltage can be changed arbitrarily, these become unnecessary.

Further, according to a fourth aspect of the present invention, there is provided an ASIC.
If the duration of the ON signal can be arbitrarily changed externally by the internal digital filter circuit, the repetitive input time interval of the input signal can be freely adjusted.

According to a fifth aspect of the present invention, a pulse width detection circuit in an ASIC is configured to ignore a short-time discontinuity of an input signal due to the influence of noise or the like and regard it as a continuous signal. Then, a load control device that is resistant to noise can be obtained.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of an AC input circuit showing one embodiment of the present invention;

FIG. 2 is a circuit configuration diagram of one unit of a control center of the present invention,

FIG. 3 is a diagram corresponding to FIG. 2 showing a conventional example,

FIG. 4 is a diagram corresponding to FIG. 1 showing a conventional example,

[Explanation of symbols]

21 is a power supply bus, 22 is an induction motor (load), 23 is a main circuit, 24 is a circuit breaker (main circuit device), 25 is an electromagnetic contactor (main circuit device), 26 is a current transformer, and 27 is zero. Phase current transformer, 28 is an operation transformer, 31 is a control circuit unit, 3
2 is a start operation switch (operation device), 33 is a stop operation switch (operation device), 34 is a logic operation circuit, 35 is a current detection circuit (detection means), 36 is a setting switch, 37 is a display circuit, and 38 is a drive circuit. (External output circuit), 39 is a signal output circuit (external output circuit), 40 is a microcomputer, 41 is an auxiliary logic operation circuit, 50 is a stray capacitance between cables, 61 is a current limiting circuit composed of a resistor and a capacitor, 62 is a bidirectional photocoupler, 63 is a bypass resistor, 64 is a voltage detection resistor, 65 is a pulse width detection circuit, and 66 is a digital filter circuit.

Claims (5)

[Claims] 1. A main circuit device such as an electromagnetic contactor interposed in a main circuit between a power supply bus and a load, an operating device for operating the main circuit device, and a detecting means for detecting a main circuit current and the like. A load control device including a logical operation circuit that controls the main circuit device and the like through an external output circuit based on an input signal from the operation device, a detection signal from the detection unit, and a program stored in advance, wherein the logical operation circuit Is provided with a microcomputer functioning as a main control circuit, and an auxiliary logic operation circuit operated by a clock for distributed processing of an input / output control function, and an AC input for operating the main circuit device. In addition to the circuit, the AC input circuit includes a current limiting circuit including a resistor and a capacitor, a bidirectional photocoupler that insulates an input signal, The circuit consists of a bypass resistor and a voltage detection resistor that do not operate the bidirectional photocoupler until a current of a certain value or more flows in the circuit, and a pulse width detection circuit and a digital filter circuit are provided inside the auxiliary logic operation circuit. Wherein the bidirectional photocoupler performs full-wave rectification on an AC input signal from an AC input circuit, outputs a pulse signal having a constant duty according to an input level, and The pulse width detection circuit detects the voltage level from the duty of the pulse signal output from the bidirectional photocoupler, and determines that the AC input signal is on when the voltage is equal to or higher than a predetermined certain voltage. The digital filter circuit in the auxiliary logic operation circuit is set in advance after the pulse width detection circuit detects that the AC input signal is on. Continued during ON signal of the time, the load control apparatus characterized by being configured to convey the next stage of the microcomputer. 2. The load control device according to claim 1, wherein said auxiliary logic operation circuit is constituted by an ASIC. 3. A pulse width detection circuit in the ASIC, wherein a predetermined voltage for judging that an AC input signal is turned on can be arbitrarily changed from the outside. Item 3. The load control device according to Item 2. 4. The digital filter circuit in the ASIC is configured so that the duration of the ON signal can be arbitrarily changed from the outside after the pulse width detection circuit detects that the AC input signal is ON. Claim 3
The load control device as described in the above. 5. The pulse width detection circuit in the ASIC can ignore an input signal that is discontinuous for a short time due to noise or the like and regard it as a continuous signal. The load control device according to claim 4.