JP3250590B2 - Control device for air conditioner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an air conditioner which performs variable capacity control.

[0002]

2. Description of the Related Art In an air conditioner which performs variable capacity control, an overcurrent detecting means is provided in its control device to protect a switching element of an inverter circuit from overcurrent. FIG. 5 shows an example of the control device. The power from an AC power supply 21 is converted into a predetermined DC voltage by a rectifier circuit 22 and a smoothing circuit 23, and is converted into an AC of a desired frequency by an inverter circuit 24. The power is supplied to the compressor 25. The inverter circuit 24 is composed of a plurality of switching elements, and these are controlled by a pulse signal from a drive circuit 27 controlled by a microcomputer 26. Inverter circuit
To detect the input current (overcurrent) of 24, a resistor 28, a short-circuit current detection circuit 29, an overcurrent integration circuit 30, a NAND gate
31 is used, and the short-circuit current detection circuit 29 is an inverter circuit 24
When a current exceeding the set value A flows for a time, a short-circuit detection signal is output to the NAND gate 31, and the overcurrent integration circuit 30 detects that the current exceeding the set value B lower than the set value A is longer than the a time. When the current flows for a long b time, an overcurrent detection signal is output to the NAND gate 31. And NAND
When one of the detection signals is detected by the gate 31, the microcomputer 26 stops the switching control of the inverter circuit 24 and cuts off the power supply to the compressor 25.

[0003]

When the short-circuit current detection circuit 29 operates to output a short-circuit detection signal, the switching element of the inverter circuit 24 is broken (short-circuited) or the winding of the compressor motor 25 is stopped. In many cases, the line is in a state of inoperability due to a rare short or inoperable state, and it is desired to judge that it is abnormal.If the overcurrent integration circuit 30 operates and outputs an overcurrent detection signal, the switching element of the inverter circuit 24 or the compression This is not necessarily the case where there is an abnormality in the winding of the machine motor 25, but is often due to noise or an overcurrent generated due to compressor overload or the like, and this does not mean that subsequent control operations cannot be performed. However, the conventional control device as shown in FIG.
Even if the operation of 25 is stopped, it is not known which of the short-circuit current detection circuit 29 and the overcurrent integration circuit 30 has operated, and there is a problem that it takes time to find the cause of the overcurrent. Therefore, an object of the present invention is to provide an air conditioner control device that solves this problem.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and comprises a rectifier circuit for converting AC to DC, a smoothing circuit for smoothing an output voltage of the rectifier circuit, and An inverter circuit including a plurality of switching elements that convert a DC input voltage from a smoothing circuit into an AC output voltage, a compressor that operates on the AC output voltage of the inverter circuit, and a drive circuit that drives the inverter circuit;
A microcomputer that controls the drive circuit, a short-circuit current detection circuit that outputs a short-circuit detection signal when an input current of the inverter circuit exceeds a set value for a predetermined time, and a setting in which the input current is lower than the set value. An overcurrent integration circuit that outputs an overcurrent detection signal when the current value exceeds the set time and flows for a time longer than the set time; an output side of the short-circuit current detection circuit is connected to an interrupt port of the microcomputer; The output side of the overcurrent detection circuit is connected to a port or a general-purpose port, and when the short-circuit detection signal is detected, the operation of the compressor is stopped. A signal is output to display an abnormality, and a process of stopping the restart of the compressor is performed. When the overcurrent detection signal is continuously detected a plurality of times, the overcurrent detection signal is output. And to perform the operation stop and abnormal display of the compressor until no out.

[0005]

With the above arrangement, the short-circuit detection signal from the short-circuit current detection circuit having a short detection time and the over-current detection signal from the over-current integration circuit having a long detection time are separately provided by the microcomputer constituting the control means. When the short-circuit detection signal is detected and the short-circuit detection signal is detected, the operation of the compressor is stopped. The restart process of the compressor is stopped, and when the overcurrent detection signal is continuously detected a plurality of times, the operation of the compressor is stopped and an abnormality is displayed until the overcurrent detection signal is not detected. Therefore, it is easy to determine whether the short-circuit current detection circuit has been activated or the overcurrent integration circuit has been activated, and the cause of the occurrence of the overcurrent can be determined more quickly.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. FIG. 1 schematically shows a control device of an air conditioner, in which 1 is an AC power supply, 2 is a rectifier circuit, 3 is a smoothing circuit, 4 is an inverter circuit composed of a plurality of switching elements, and 5 is inverter-controlled. 6 is a drive circuit for driving the inverter circuit, and 7 is a drive circuit 6
8 is a resistor for detecting the input current of the inverter circuit 4, and 9 is when the input current of the inverter circuit 4 exceeds a set value and flows for a predetermined time, that is, A short-circuit current detection circuit that outputs a short-circuit detection signal when an overcurrent flows due to a short-circuit accident of a switching element or the like. 10 is a setting in which the input current of the inverter circuit 4 is set lower than the set value of the short-circuit current detection circuit 9 This is an overcurrent integration circuit that outputs an overcurrent detection signal when the current exceeds a predetermined time (for example, 50 microseconds) longer than the predetermined time. The output side of the overcurrent integration circuit 10 is connected to an interrupt port, and is connected to a general-purpose port of the microcomputer 7.

[0007] The power from the AC power supply 1 is converted into a predetermined DC voltage by the rectifier circuit 2 and the smoothing circuit 3 and supplied to the inverter circuit 4. The switching of a plurality of switching elements constituting the inverter circuit 4 is controlled by a pulse signal from a drive circuit 6 controlled by a microcomputer 7. The short-circuit detection signal detected by the short-circuit current detection circuit 9 is input to an interrupt port of the microcomputer 7, while the overcurrent detection signal detected by the overcurrent integration circuit 10 is input to a general-purpose port of the microcomputer 7. Although not shown, the microcomputer 7 includes a signal generator for generating a PWM signal necessary for inverter control, a timer circuit, a comparator, and a storage unit. When a short-circuit detection signal is detected, the microcomputer 7 compresses the signal. When the operation of the compressor 5 is stopped, and when the short-circuit detection signal is continuously detected a plurality of times, an abnormality signal is output to display an abnormality on the indoor unit (not shown) and stop the restart of the compressor 5. Perform processing. When the overcurrent detection signal is continuously detected a plurality of times, the operation of the compressor 5 is stopped and the abnormality is displayed until the overcurrent detection signal is no longer detected.

Hereinafter, the operation of the microcomputer 7 will be described with reference to the flowcharts of FIGS. FIG. 2 shows the operation on the interrupt port side.
In step ST1, the compressor 5 is stopped. In step ST2, it is determined whether or not the start-up is within A seconds. If it is within A seconds, the short-circuit detection counter is set to +1 in step ST3. The operation of setting 1 is repeated. FIG.
Is work on the general-purpose port side (inverter signal output interrupt)
Then, the inverter drive signal switching time is set in step ST1, the signal of the general-purpose port is read in step ST2, it is determined whether or not an overcurrent detection signal is present in step ST3. If the overcurrent detection signal is not detected, The overcurrent detection counter is reset in step ST8, the next switching time is calculated in step ST9, and the process proceeds to step ST10. If it is determined in step ST2 that an overcurrent detection signal is present, the overcurrent detection counter is incremented by +1 in step ST5. In step ST6, it is determined whether or not the overcurrent detection counter has reached x times. If the counter has not reached x times, the process proceeds to step ST9. If it has reached x times, the compressor is started in step ST7. The work of stopping is repeated.

FIG. 4 shows the work in the main routine. If a short-circuit detection signal is detected in step ST1, the process proceeds to step ST2 to determine whether or not the count of the short-circuit detection counter has reached y times. When the number of times has reached y, an abnormal signal is output in step ST3, an abnormal display is performed on the indoor unit (not shown), and the abnormal signal is displayed in step ST4.
In step ST1, a restart stop process (permanent stop process) of the compressor 5 is performed, and the operation is terminated. When the short-circuit detection signal is not detected in step ST1, the process proceeds to step ST5 and the overload detection signal is detected. It is determined whether or not an abnormal signal is output only when the compressor 5 is stopped in accordance with the control rule described with reference to FIG.

[0010]

According to the above-described control device, when a switching element or the like is short-circuited, an abnormality is displayed, and the restart of the compressor is permanently stopped.
On the other hand, if an overcurrent occurs due to overload operation of the compressor, etc., the compressor is stopped only when the overcurrent state continues, and an error display is displayed. It is possible to know whether the circuit has been operated or the overcurrent integration circuit has been operated, which is useful for investigating the occurrence of an abnormality and is convenient.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram of a control device for an air conditioner according to an embodiment of the present invention.

FIG. 2 is a flowchart schematically showing a control operation according to the present invention.

FIG. 3 is a flowchart schematically showing a control operation according to the present invention.

FIG. 4 is a flowchart schematically showing a control operation according to the present invention.

FIG. 5 is a circuit block diagram of a control device of an air conditioner showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 AC power supply 2 Rectifier circuit 3 Smoothing circuit 4 Inverter circuit 5 Compressor (compressor motor) 6 Drive circuit 7 Microcomputer (microcomputer) 8 Resistor 9 Short circuit current detection circuit 10 Overcurrent integration circuit

Claims (2)

(57) [Claims] 1. A rectifying circuit for converting an alternating current into a direct current, a smoothing circuit for smoothing an output voltage of the rectifying circuit, and a plurality of switching elements for converting a DC input voltage from the smoothing circuit into an AC output voltage. An inverter circuit, a compressor that operates on the AC output voltage of the inverter circuit, a drive circuit that drives the inverter circuit, a microcomputer that controls the drive circuit, and an input current of the inverter circuit that exceeds a set value. A short-circuit current detection circuit that outputs a short-circuit detection signal when a predetermined time has passed, and an over-current detection signal that outputs an overcurrent detection signal when the input current has flown for a time longer than the set time exceeding a set value lower than the set value. A current integration circuit; an output side of the short-circuit current detection circuit connected to an interrupt port of the microcomputer; The output side of the overcurrent detection circuit is connected to the application port, and when the short circuit detection signal is detected, the operation of the compressor is stopped, and when the short circuit detection signal is continuously detected a plurality of times, an abnormal signal is output. Outputs an error display and performs a restart stop process of the compressor. When the overcurrent detection signal is continuously detected a plurality of times, the operation of the compressor is stopped until the overcurrent detection signal is no longer detected. And an abnormality display. 2. The control device for an air conditioner according to claim 1, wherein the abnormality display is performed on the indoor unit side.