JP2791928B2 - Inverter control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverter control apparatus for operating an induction motor at a variable speed, and more particularly to an inverter operation abnormality.

[0002]

2. Description of the Related Art FIG. 4 is a block diagram showing an entire configuration of a conventional inverter control device, and FIG. 5 is a block diagram showing a main part of the inverter control device. In the figure, 100 is an inverter device, 200 is an inverter, 300 is an inverter control device, 1 is a three-phase AC power supply, 2 is a converter unit,
3 is an inrush current suppressing resistor, 4 is a smoothing capacitor, and 5 is an inverter. The inverter 200 has two converter units 2
It is composed of an inverter unit 5. 6 is an induction motor, 7
Is a current detection circuit for detecting a load current on the output side of the inverter section 5;
A microprocessor that calculates an integrated value of the heat generation amount of 0 and determines an abnormality, 9 is a ROM, and 10 is a RAM. Inverter control device 300 includes current detection circuit 7 to RAM 10. Reference numeral 11 denotes a relay means provided at an inverter abnormal stop signal output terminal to which an inverter abnormal stop signal from the microprocessor 8 is input.

Reference numeral 21 denotes an inverter control circuit for outputting a drive control signal to the inverter section 5, and 22 calculates an integrated value of the heat generation of the induction motor 6 and the inverter 200 per predetermined time from the current detection signal of the current detection circuit 7. The heating value calculation circuit 23 is an abnormal stop determination circuit that determines whether to stop the inverter 200 based on the integrated value of the heating value calculated by the heating value calculation circuit 22.

Next, the operation of the above-described conventional example in an abnormal state will be described with reference to the flowcharts of FIGS. First, the power supply of the inverter device 100 is turned on, and the inverter unit 5 is driven by the drive control signal from the inverter control circuit 21 to perform the inverter operation (step S1). This also includes the case where the inverter operation is restarted after resetting. Next, during the operation of the inverter, the current detection circuit 7 detects the load current of the inverter unit 5, and the heat generation amount calculation circuit 22 of the microprocessor 8 outputs the current detection circuit 7.
Then, the integrated value per predetermined time of the calorific value of the induction motor 6 and the inverter 200 is calculated and calculated from the detected value (step S2). The integrated value is obtained by calculating the following equations. MQ = Σ ｛(detected load current / inverter rated current) ² −P｝ T In the above equation, MQ is the motor heat generation integrated value, P is the number of cooling systems, and T is the current sampling time (unit is seconds). IQ = Σm (Pu) T In the above equation, IQ is the integrated heat generation value of the inverter, m is the frequency characteristic, Pu is the thermal coefficient, and T is the current sampling time (unit is seconds). The abnormal stop determination circuit 23 compares the integrated value X of the heat value calculated by the heat value calculation circuit 22 with the protection function operation level value Z indicating the limit of the heat generation abnormality (step S3). Is equal to or greater than the protection function operation level value Z, the abnormal stop determination circuit 23 outputs an inverter drive stop command to the inverter control circuit 21, and the inverter stop circuit outputs the drive stop signal from the inverter control circuit 21. The unit 5 stops driving and the inverter 200 stops abnormally (Step S
4). At the same time, the abnormal stop judging circuit 23 outputs to the relay means 11 an inverter abnormal stop signal indicating that the inverter drive stop command has been output to the inverter control circuit 21. Upon receiving the inverter abnormal stop signal, the relay means 11 is driven to close the normally open contact, and display means (not shown) connected to the normally open contact via the abnormal stop signal output terminal operates to operate the inverter abnormally. Display a stop. If the integrated value X of the heat generation amount calculation circuit 22 is smaller than the protection function operation level value Z, the process returns to step S12, and the inverter operation is continued.

[0005]

In the conventional inverter control device, the abnormal stop judging circuit 23 calculates the integrated value X of the calorific value calculated by the calorific value calculating circuit 22 based on the detected value of the load current of the current detecting circuit 7. The protection function operation level value Z is compared. If the integrated value X is equal to or greater than the protection function operation level value Z, an inverter drive stop command is output to the inverter control circuit 21 to cause the inverter 200 to stop abnormally. Therefore, the inverter 200 and the induction motor 6 stop abnormally without knowing the sign of the abnormal stop of the inverter 200 caused by heat generation during the inverter operation, so that the inverter 200 cannot be operated for a long time. there were.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide an inverter control device capable of detecting a sign of an abnormal stop of the inverter due to heat generation during the operation of the inverter and allowing the inverter to continue operating for a long time. And

[0007]

An inverter control device according to the present invention includes, in addition to an inverter control circuit, a current detection circuit for detecting a load current on the output side of an inverter section, and a motor and an inverter based on detection values of the current detection circuit. The calorific value calculation circuit that calculates the integrated value of the calorific value is compared with the integrated value of the calorific value calculation circuit and the protection function operation level value, and the integrated value is equal to or greater than the protection function operation level value. Abnormal stop determination circuit that outputs a drive stop command to the inverter control circuit, and compares the integrated value of the calorific value calculation circuit with a warning operation level value that is lower than the protection function operation level value. And an abnormal stop warning circuit for outputting an output reduction command to the inverter control circuit when the output is equal to or more than the above.

[0008]

In the present invention, during the operation of the inverter, the current detection circuit detects the load current of the inverter section, and the heat generation amount calculation circuit calculates the integrated value of the heat generation amount of the motor and the inverter from the detection value of the current detection circuit. I do. The abnormal stop determination circuit compares the integrated value of the heat generation amount calculation circuit with the protection function operation level value, and the abnormal stop warning determination circuit compares the integrated value of the heat generation amount calculation circuit and the warning operation level value lower than the protection function operation level value. And try to compare. Therefore, if the integrated value of the heat generation amount calculation circuit is equal to or higher than the warning operation level value and smaller than the protection function operation level, the abnormal stop warning determination circuit outputs a power reduction command to the inverter control circuit, and The control circuit outputs a drive control signal of output reduction to the inverter unit to reduce the output of the inverter,
Prevent the inverter from stopping abnormally. In addition,
If the integrated value of the calorific value calculation circuit is equal to or greater than the protection function operation level value, the abnormal stop determination circuit outputs a drive stop command to the inverter control circuit, and the inverter control circuit notifies the inverter unit of the drive stop. Outputs a drive control signal and causes the inverter to stop abnormally.

[0009]

FIG. 1 is a block diagram showing a main part of an embodiment of the present invention, and FIG. 2 is a block diagram showing an entire configuration of the embodiment. In the figure, the same components as those of the conventional example are denoted by the same reference numerals as those of the conventional example, and the description of the same components will be omitted. Reference numeral 18 denotes a microprocessor that calculates the amount of heat generated by the induction motor 6 and the inverter 200 from the operation control of the inverter 200 and the detection current of the current detection circuit 7 based on the same formula as in the conventional example, and determines abnormality. 24 is an abnormal stop determination circuit that determines whether to stop the inverter 200 based on the integrated value of the calorific value calculated by the calorific value calculation circuit 22, and 25 is the integrated value of the calorific value calculated by the calorific value calculation circuit 22. An abnormal stop warning determination circuit that determines whether to issue an abnormal stop warning based on the determination. The microprocessor 18 according to the present embodiment includes an inverter control circuit 21 to an abnormal stop warning determination circuit 25. Reference numeral 26 denotes a transistor switching element provided at an abnormal stop warning signal output terminal to which an inverter abnormal stop warning signal from the abnormal stop warning determination circuit 25 is input.

Next, the operation of the above embodiment in the abnormal state will be described with reference to the flowcharts of FIGS. 1, 2 and 3. First, the power supply of the inverter device 100 is turned on, and the inverter unit 5 is driven by the drive control signal from the inverter control circuit 21 to perform the inverter operation (step S11). This also includes the case where the inverter operation is restarted after resetting. Next, during the operation of the inverter, the current detection circuit 7 detects the load current of the inverter unit 5, and the heat generation amount calculation circuit 22 of the microprocessor 18 calculates the heat generation of the induction motor 6 and the inverter 200 based on the detection value of the current detection circuit 7. The integrated value of the amount is calculated and calculated (step S1).
2). In the abnormal stop warning determination circuit 25, the heat generation amount calculation circuit 2
2 compares the integrated value X of the calorific value calculated with the warning operation level value Y which is, for example, 85% of the protection function operation level value indicating the limit of the heat generation abnormality (step S13). Then, the operation of the inverter 200 is continued. If X ≧ Y, the abnormal stop warning determination circuit 25
Outputs an output reduction command to the inverter control circuit 21 and outputs an inverter abnormal stop warning signal indicating that the output reduction command has been output to the transistor switching element 26. (Step 14). The inverter control circuit 21 that has received the output decrease command outputs a drive control signal for decreasing the output to the inverter unit 5 to decrease the output of the inverter 200 and continue the operation of the inverter 200. Further, the transistor switching element 26 receiving the inverter abnormal stop warning signal is turned on, and a warning display means (not shown) connected to the transistor switching element 26 via an inverter abnormal stop warning signal output terminal outputs an abnormal stop warning. Is displayed.

Further, the abnormal stop judging circuit 24 calculates the integrated value X
And the protection function operation level value Z indicating the limit of the heat generation abnormality is compared (step S15). If X <Z, the process shifts to step S12 to continue the operation of the inverter 200.
If ≧ Z, the abnormal stop determination circuit 24 outputs a drive stop command to the inverter control circuit 21 and the relay unit 11
Output an inverter abnormal stop signal. The inverter control circuit 21 that has received the drive stop command causes the inverter unit 5
And outputs a drive control signal for stopping the output to the inverter 200.
Is abnormally stopped (step 16). Upon receiving the inverter abnormal stop signal, the relay means 11 is driven to close the normally open contact, and a display means (not shown) connected to the normally open contact via an inverter abnormal stop signal output terminal.
Operates and displays the inverter abnormal stop.

[0012]

As described above, according to the present invention, the calorific value calculation circuit calculates the integrated value of the calorific value of the motor and the inverter from the detection value of the current detection circuit which detects the load current of the inverter during the inverter operation. The abnormal stop warning judgment circuit compares the integrated value with a warning operation level value lower than the protection function operation level value of the abnormal stop judgment circuit, and when the integrated value is equal to or greater than the warning operation level value, the inverter stops. An output reduction command is output to the control circuit, and the inverter control circuit outputs an output reduction drive control signal to the inverter to reduce the output of the inverter.This prevents the inverter from stopping abnormally. ,
This has the effect that the inverter can be operated for a long time.

[Brief description of the drawings]

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

FIG. 2 is a block diagram showing an overall configuration of the embodiment.

FIG. 3 is a flowchart showing the operation of the embodiment.

FIG. 4 is a block diagram showing an overall configuration of a conventional inverter control device.

FIG. 5 is a block diagram showing a main part of the inverter control device.

FIG. 6 is a flowchart showing an operation of the inverter control device.

[Explanation of symbols]

 5 Inverter section 7 Current detection circuit 21 Inverter control circuit 22 Heat generation amount calculation circuit 24 Abnormal stop control circuit 25 Abnormal stop warning control circuit

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H02M 7/42-7/98 G05F 1/00-1/10 H02P 5/408-5/412 H02P 7 / 628-7/632

Claims (1)

(57) [Claims] 1. An inverter control device comprising an inverter control circuit for driving and controlling a converter unit to which an AC power is input and an inverter unit connected via a smoothing capacitor to output a predetermined voltage and frequency. A current detection circuit for detecting the load current on the output side of the motor; a calorific value calculating means for calculating the integrated value of the calorific value of the motor and the inverter from the detected value of the current detecting circuit; Level value, and if the integrated value is equal to the protection function operation level value,
Above that, an abnormal stop determination circuit that outputs a drive stop command to the inverter control circuit, a comparison between the integrated value of the heat generation amount calculation circuit and a warning operation level value lower than the protection function operation level value, and the integrated value is An inverter control device comprising: an abnormal stop warning determination circuit that outputs an output reduction command to the inverter control circuit when the output level is equal to or greater than the warning operation level value.