JPH05316637A - Motor controller - Google Patents

Abstract

PURPOSE:To automatically set a reference value for discriminating abnormality which is the optimum for protecting conditions by taking the ambient temperature into consideration. CONSTITUTION:A storage circuit 22 obtains temperature data of a motor 2 under an actually loaded state which changes at every operating time from a temperature detector 2a for measuring the ambient temperature of the motor 2 and stores the data. A temperature compensation circuit 19 performs temperature correction on a plurality of kinds of current values stored in advance in the circuit 19 as reference values for discriminating abnormality based on the temperature data stored in the circuit 22. A setting circuit 18 predictively calculates in advance temperature variation from a current value and conducting time from a current converter 5 and sets the thermal current pattern of the motor 2. An automatic setting circuit 20 selects the temperature-corrected current pattern which is the closest to a preset condition by comparing the plurality of kinds of temperature-corrected current patterns from the circuit 19 with the thermal current pattern of the motor 2 for which the temperature variation is predictively calculated at the circuit 18 and sets the selected current pattern as a reference value for discriminating abnormality.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric motor control device for controlling opening / closing and protecting an electric motor by using a switch such as an electromagnetic contactor, and more particularly, to automatically determine a reference value for judgment for performing a protective operation. The present invention relates to an electric motor control device that can be set.

[0002]

2. Description of the Related Art Recently, by applying a microcomputer in a unit device or the like of a control center, there has been provided an electric motor control device having a large number of functions such as operation / stop, control, protection and monitoring of an electric motor. ing.
The protection function of this type of motor control device constantly monitors the main circuit current of the motor to compare it with the reference value for abnormality determination, and when an abnormality such as overload, open phase or ground fault is detected, the electromagnetic circuit connected to the main circuit is detected. Protect the electric motor by opening the contactor,
Further, the cause of the abnormality is displayed outside.

[0003]

By the way, the setting of the reference value for abnormality determination in such a control center is carried out by actually measuring the starting current, the starting time and the steady current of the electric motor at the installation site. The reference value at temperature is decided and set.
However, in this case, if the set current is larger than the steady value, overload protection cannot be performed, and if the set time is short, malfunction occurs at start-up, and if the set current is too long, there is a problem that the electric motor cannot withstand and the protection cannot be performed. However, since all of them have the protection characteristic of the steady temperature, the thermal protection corresponding to the actual temperature change during the operation has not been made. Therefore, an object of the present invention is to provide an electric motor control device capable of automatically setting a reference value for abnormality determination that is optimum for a protection condition by taking ambient temperature into consideration.

[0004]

An electric motor controller according to the present invention includes an electromagnetic contactor for opening and closing a main circuit between a power bus and an electric motor, a current converter for detecting a main circuit current, and an opening and closing of the electromagnetic contactor. Input circuit for inputting a start and stop operation signal to determine whether or not there is an abnormality by comparing the detection signal from the current converter with a reference value for abnormality determination, and outputs a command to open the electromagnetic contactor when an abnormality occurs. In a motor control device including a logical operation circuit, a temperature detector that measures the ambient temperature of the motor or the control center, obtains temperature data at an actual load that changes with each operating time, and stores the temperature data, and an abnormality. A temperature correction circuit that performs temperature correction based on temperature data stored in the storage circuit of a plurality of types of current patterns that are stored in advance as a reference value for determination; A preset circuit that compares the current value from the temperature controller and a plurality of types of current patterns temperature-corrected by the temperature correction circuit with a setting circuit that predicts and calculates the temperature change from the current value and the energization time and sets the thermal current pattern of the motor And an automatic setting circuit for selecting a temperature-corrected current pattern that is closest to the above and setting it as the abnormality determination reference value.

[0005]

When the ambient temperature of the electric motor or the control center is stored in the storage circuit, the temperature is corrected to a plurality of pre-stored current patterns, and the thermal tolerance of the electric motor is predicted and calculated in advance. The current pattern is compared with the current pattern, and at least one current pattern closest to the protection condition is automatically selected as the abnormality determination reference value.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, reference numeral 1 is a three-phase main circuit that supplies power to an induction motor 2 that is a load. The main circuit 1 includes a circuit breaker 3 for wiring, an electromagnetic contactor 4, and a main circuit current for detecting the current. The current converter or current transformer 5 and the zero-phase current transformer 6 for detecting the zero-phase current of the main circuit are interposed as main circuit devices. The primary winding 7a of the operating transformer 7 is connected between the two phases of the main circuit 1 between the load side of the wiring breaker 3 and the power source side of the electromagnetic contactor 4. The output voltage of the secondary winding 7b of the operating transformer 7 is applied to the bus bar 8 as a power source for the operating circuit. The coil 4a of the electromagnetic contactor 4 having one end connected to the bus bar 8 so as to use it as one power supply line, the auxiliary contact 4b, the start operation switch 9, and the other end of the stop operation switch 10 have the control circuit 11 Operation signal output terminal 1
1a and the operation signal input terminal 11b.

As a result, the control circuit 11 receives the start signal from the start operation switch 9 and the stop signal from the stop operation switch 10 to turn off the coil 4a, thereby opening and closing the electromagnetic contactor 4 and changing the voltage. Input current signals from the current transformer 5 and the zero-phase current transformer 6 to protect the induction motor from overload,
It has the function of performing protection operations such as open-phase protection and ground fault protection. The power of the control circuit 11 is supplied from the tertiary winding 7c which is insulated from the secondary side of the operation transformer 7 in order to prevent intrusion of switching noise generated by the coil 4a of the electromagnetic contactor 4. There is.

Further, the control circuit 11 inputs a detection current corresponding to the magnitude of the main circuit current output from the current transformer 5 and the zero-phase current transformer 6, and the current detection circuit 1;
The logical operation circuit 14 for calculating the detection signal from the circuit 2 to monitor the abnormality of the main circuit current and outputting a command to the drive circuit 13 for opening and closing the electromagnetic contactor 4, the main circuit current value and the main circuit 1
The display circuit 15 for displaying the cause of the abnormality and the external output circuit 16 for outputting the abnormality content to the outside.

The control circuit 11 is further provided with a circuit described below for the purpose of the present invention. That is, the control circuit 11 is provided with a memory circuit 17, and the memory circuit 17
The temperature data of the temperature detector 2a that measures the ambient temperature of the electric motor 2 under an actual load is stored in. Also, the temperature correction circuit 1
The data of the rate of change (%) of the rated current with respect to the ambient temperature is pre-stored in 9, and the temperature data measured by the temperature detector 2a is used to set a plurality of kinds of set currents as the reference value for abnormality determination as shown in FIG. The patterns I ₁ , I ₂ and I ₃ are shown in FIG.
Are corrected to become I ₄ , I ₅ , and I ₆ , and are set in the form of a function of time (current pattern). In FIG. 2, I ₀ indicates a common lowest level region of the set current patterns I _{1 to} I ₃ .

On the other hand, in the setting circuit 18, the thermal current pattern of the induction motor in which the temperature change is predicted and calculated in advance from the current value from the current transformer 5 and the energization time is the current pattern I _7a at room temperature as shown in FIG. Current pattern I that predictively calculated temperature and temperature
_7b is set as a function of time. The comparison circuit 22 sets the preset current patterns I _{4 to} I ₆ in the temperature correction circuit 19 and the predicted calculated thermal current pattern I _7a in the setting circuit 18,
I _7b is compared with the logical operation circuit 14 to perform a comparison operation, and one set current pattern closest to a predetermined condition is selected, and the logical operation circuit 14 automatically sets the selected set current pattern. The automatic setting is set to 20. Such automatic setting is performed only when the setting switch 21 is manually turned on. Next, the operation of the above configuration will be described.

First, the operation of automatically setting the reference value for abnormality determination will be described. When the electric motor 2 is operated in the actual load state with the setting switch 21 turned on, the temperature detector 2a detects the ambient temperature and the temperature data is stored in the memory circuit 17. Set current pattern I _{1 in the} temperature correction circuit 19
Through I ₃ become current patterns I ₄ through I ₆ whose temperature is corrected by the temperature data. This current pattern is the comparison circuit 2
2 and the logical operation circuit 14 perform a comparison operation with the thermal current patterns I7a and I7b in the setting circuit 18. This comparison is performed with respect to the magnitude of the current value on the same time axis. For example, first, it is compared with the set current pattern I _4, and as a result of this comparison, at least one of the thermal current patterns I _7a and I _7b is obtained. When there is a time region in which the section indicates the set current I ₄ or more (I ₄ is in this state in FIG. 3), the process proceeds to the next comparison operation with I _5, and the same comparison operation is repeated thereafter. By this comparison calculation, among the set current patterns I _{4 to} I ₆ ,
The set current pattern closest to the thermal current pattern I _7b , that is, I _{5 in} this example, is automatically set in the automatic setting circuit 20 as an abnormality determination reference value having the closest relation to the protection condition.
After that, this reference value for abnormality determination is used for abnormality determination.

In the above embodiment, the ambient temperature of the electric motor has been described as the temperature data, but the same set current can be set even at the ambient temperature of the control center by catching the difference between the ambient temperature of the electric motor and the ambient temperature of the control center installation room. Patterns I _{4 to} I ₆ are obtained.

In a normal operating condition, the detected current of the main circuit 1 output from the current transformer 5 and the zero-phase current transformer 6 is converted into a predetermined signal by the current detector 12, and this is converted into a predetermined signal. As described later, an overload is performed by performing a logical operation of comparing with a set current pattern automatically set in the automatic setting circuit 20, that is, a reference value for abnormality determination or other reference values.
We constantly monitor for abnormalities such as open phases and ground faults. When an abnormality occurs, the logical operation circuit 14 causes the drive circuit 1
3 and the display circuit 15 output the opening operation command of the electromagnetic contactor 4 and the display command of the content of abnormality.

[0014]

According to the present invention, the ambient temperature of the electric motor or the control center is obtained as the temperature data by the operation of the electric motor, and the plural kinds of current patterns which are built in in advance are automatically temperature-corrected. The calculated current pattern is compared with the current value from the current converter and the thermal current pattern of the motor, which predicts the temperature change based on the energization time, and the current pattern that is closest to the predetermined condition is automatically calculated. Since this is automatically selected and automatically set as the reference value for abnormality determination, the optimum reference value can always be set, and since this can be done automatically, the excellent effects such as extremely easy setting work can be achieved. Can be expected.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of a motor control device according to the present invention.

FIG. 2 is a diagram showing a current characteristic which is built in advance.

FIG. 3 is a diagram showing a motor thermal current characteristic and a current characteristic which is a protection condition.

[Explanation of symbols]

1 is a main circuit, 4 is an electromagnetic contactor, 5 is a current transformer (current converter), 6 is a zero-phase current transformer, 11 is a control circuit, 12 is a current detection circuit, 14 is a logical operation circuit, and 17 is a memory. Circuit, 18 setting circuit, 19 temperature correction circuit, 20 automatic setting circuit,
Reference numeral 22 is a comparison circuit, and 2a is a temperature detector.

Claims (1)

[Claims] 1. An electromagnetic contactor for opening and closing a main circuit between a power bus and an electric motor, a current converter for detecting a main circuit current, and an input for inputting start and stop operation signals for opening and closing the electromagnetic contactor. In a motor control device comprising a circuit and a logical operation circuit that compares the detection signal from the current converter with a reference value for abnormality determination to determine the presence or absence of abnormality and outputs an opening command of the electromagnetic contactor at the time of abnormality, A temperature detector that measures the ambient temperature of the electric motor or control center, obtains temperature data at actual load that changes with each operating time, and stores it, and a plurality of pre-stored abnormality reference values. Temperature correction circuit that corrects the temperature based on the temperature data stored in the storage circuit, and the temperature change is predicted in advance from the current value from the current converter and the energization time. A temperature-corrected current pattern that is closest to a predetermined condition by comparing with a setting circuit that performs a measurement operation to set a thermal current pattern of the electric motor and a plurality of types of current patterns that have been temperature-corrected by the temperature correction circuit. And an automatic setting circuit for selecting this and setting it as the reference value for abnormality determination.