JPH08182306A - Air conditioner - Google Patents

Abstract

PURPOSE: To effectively inform the abnormal state of an active filter or an active filter controller. CONSTITUTION: A controller 6 and an active filter controller 7 are operated by individual power sources 17, 18 and a signal representing the normal state is always inputted from the controller 7 to the controller 6 by state detecting means 7c. When the signal from the controller 7 is at a high level, the controller 6 judges that an active filter 9 or the controller 7 is normal. When the filter 9 is abnormal or the power supply to the controller 7 is interrupted, a signal having a low level is inputted to the controller 6. The controller 6 judges that the filter 9 or the controller 7 is abnormal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner having an inverter circuit for changing the frequency of an electric compressor of an outdoor unit so that an optimum capacity can be obtained according to an air conditioning load,
In particular, the present invention relates to an air conditioner equipped with an active filter for the purpose of power factor improvement and power supply harmonic current suppression.

[0002]

2. Description of the Related Art Conventionally, an air conditioner of this type has a refrigeration cycle in which a compressor, a condenser, a decompressor, an evaporator and the like are sequentially connected to each other, and driving power is further supplied to the compressor. An inverter unit is provided, and the output frequency of the inverter unit is controlled according to the load, so that the optimum capacity corresponding to the load is obtained, and the comfort and the energy saving effect are improved. In this inverter unit, a capacitor-input type DC power supply circuit that rectifies an input voltage from an AC power supply with a rectifying circuit such as a diode bridge and supplies it to a power device forming an inverter unit as a DC smoothing voltage with a smoothing capacitor. have.

In such a capacitor input type power supply circuit, the input current flows only when the input voltage is higher than the DC smoothing voltage as shown in FIG. There are problems such as loss and adverse effects of harmonic current on the power bus.
As a countermeasure against this problem, a passive filter such as a reactor has been conventionally used, but it has not been fundamentally improved.

Therefore, an active filter composed of a switching element such as a transistor, a choke coil, a diode for high-speed switching is used, and the active filter is mounted on an air conditioner to solve the above problems. What was done is Japanese Patent Laid-Open No. 4-263.
No. 74 publication.

[0005]

If the active filter is mounted on the inverter unit having the capacitor input type power supply circuit as described above, the power factor can be improved and the harmonic current of the power supply can be suppressed. In general, the active filter control unit for controlling and the control unit for controlling the entire air conditioner are often insulated from each other, and the control unit and the active filter control unit are operated by separate power sources, and signals of both control units are operated. The exchange is performed via a photo coupler. However, in this case, if an abnormality such as interruption of power supply to the active filter control unit occurs for some reason, the active filter control unit does not operate, and there is no means for notifying the control unit of the abnormality. Therefore, the electric compressor cannot be stopped, and the electric compressor continues to be driven even though the active filter is stopped, and the electric compressor is locked due to insufficient voltage applied to the electric compressor. Such a secondary failure will be caused.

As the active filter, a step-up type filter is generally used because of its cost. In this boosting type active filter, the input voltage of the commercial power source is boosted to a voltage higher than the rectified and smoothed potential by the choke coil and the switching element, and is supplied to the inverter unit via the smoothing capacitor. Due to this boosting operation, the output voltage of the active filter is always higher than the input voltage, and the output voltage easily rises and falls due to the balance with the load.

Therefore, in the active filter control section,
Feedback is constantly applied to keep the output voltage constant. In other words, the output voltage is likely to fluctuate for the above reasons, and an output voltage detection unit that detects the output voltage of the active filter is provided to prevent excessive boosting from the viewpoint of withstanding voltage protection of components, even if the output voltage fluctuates. The active filter is controlled so that the set value from the control unit is obtained. Also,
The output voltage information from the output voltage detection unit is also input to the control unit.When the output voltage exceeds the set value and rises above a certain voltage value, the control unit stops the electric compressor or the inverter unit When it is determined that an abnormality has occurred, the boosting operation by the active filter is stopped (overvoltage protection function).

However, when the output voltage is boosted to a set value at the start of driving the active filter, or at the start or stop of the operation of the inverter, or when the electric compressor is started or stopped, the output voltage is not constant for a certain period of time. It becomes stable and may exceed the set value for a moment. In this case, it is determined that each part is operating normally but is in an abnormal state, and the boosting operation of the active filter is stopped by the overvoltage protection function described above, so stable operation of the air conditioner is performed. Could not be done.

In view of the above, an object of the present invention is to provide an air conditioner capable of reliably notifying an abnormal state of an active filter or an active filter control section and preventing erroneous detection of the abnormal state.

[0010]

As shown in FIGS. 1 and 2, a means for solving the problems according to the present invention comprises a control unit 6 for controlling the output frequency of the inverter unit 4 according to an air conditioning load, and an input current waveform for the input voltage. And an active filter 9 that matches the phase and outputs the same to the inverter unit 4, and an active filter control unit 7 that drives the active filter 9 based on a control signal from the control unit 6. The active filter 9 and the active filter control unit are provided. 7 is provided with abnormality detecting means for detecting and notifying both or one of the abnormal states, and the control section 6 and the active filter control section 7 are operated by individual power sources 17 and 18, respectively, and the abnormality detecting means is provided. Is for inputting an abnormality detection signal to the control unit 6 even if the power supply to the active filter control unit 7 is interrupted.

The inverter unit 4 is stopped when the active filter 9 or the active filter control unit 7 is abnormal or stopped, and the active filter 9 is stopped when the inverter unit 4 is abnormal or stopped.

Further, as shown in FIG. 3, the control unit 6 does not detect an abnormal state immediately after the operation of the inverter unit 4 is started or stopped, or immediately after the driving of the active filter 9 is started (abnormality detection period A). ) Is set.

[0013]

In the above-mentioned means for solving the problems, the control section 6 and the active filter control section 7 are provided with individual power sources 17,
A signal indicating a normal state is always input from the active filter control section 7 to the control section 6 by the abnormality detection means. The control unit 6 determines that the active filter 9 or the active filter control unit 7 is normal, and the normal driving operation is continued. When the power supply to the active filter control unit 7 is interrupted for some reason, the driving of the active filter 9 is stopped, the abnormality detection signal is input to the control unit 6, and the control unit 6 controls the active filter 9 or the active filter. It is determined that the section 7 is in an abnormal state.

When the active filter 9 or the active filter control section 7 is in an abnormal state or is stopped, a stop signal is immediately output to the inverter section 4 to stop the inverter section 4. As a result, the electric compressor 5 will not stop due to lack of applied voltage due to a lock.

When the inverter section 4 is in an abnormal state or is stopped, a stop signal is output to the active filter 9 to stop the active filter 9. This can suppress an increase in output voltage.

Further, the control unit 6 causes an abnormal state during an abnormality-free detection period A immediately after the inverter unit 4 is started or stopped, or the active filter 9 is started to be driven, when the output voltage becomes unstable for a moment. Even if the signal shown is input, the active filter 9 or the inverter unit 4 is not stopped. This enables stable operation.

[0017]

FIG. 1 is a block diagram of an inverter circuit of an air conditioner equipped with an active filter showing an embodiment of the present invention. In FIG. 1, 1 is a commercial power supply, and 2 is a rectifying bridge that full-wave rectifies the AC voltage of the commercial power supply 1.
3 is a smoothing capacitor for smoothing the rectified voltage to DC, 4
Is an inverter unit composed of six transistors and diodes for inputting a smoothed DC voltage and outputting a three-phase AC voltage to a three-phase electric compressor 5, and 6 controls the inverter unit 4 according to the air conditioning load. The control unit 7 is an active filter control unit that drives the active filter 9 by a control signal transmitted from the control unit 6 via the interface unit 8.

Here, in the case of an inverter circuit in which the active filter 9 is not mounted, the input voltage which is full-wave rectified by the rectifying bridge 2 is smoothed by the smoothing capacitor 3,
DC power is supplied to the inverter unit 4. In this case,
The rectification current flowing through the rectification bridge 2 flows only when the input voltage is higher than the DC smoothing voltage as shown in FIG. 4, and a power supply harmonic current is generated. Therefore, the active filter 9 is provided between the rectifying bridge 2 and the smoothing capacitor 3. The active filter 9 includes a choke coil 10, a fast recovery diode (FRD) 11,
The power device 12 is a switching element, and is driven by a control signal from the active filter controller 7.

The active filter control unit 7 includes an input voltage detection circuit 13 between the rectifying bridge 2 and the active filter 9, an output voltage detection circuit 14 between the active filter 9 and the smoothing capacitor 3, and power. Each device 12 is connected. The active filter control unit 7 detects the normal driving means 7 a that boosts the input voltage from the rectifying bridge 2 based on the control signal from the control unit 6 and supplies the boosted voltage to the inverter unit 4, and the output voltage to the inverter unit 4. Then, it has a voltage adjusting means 7b for making the output voltage constant, and is provided with an abnormality detecting means for detecting an abnormal state of the active filter 9 and notifying the control section 6.

The input voltage detection circuit 13 and the output voltage detection circuit 14 are, for example, resistors and the like. The active filter controller 7 divides the input voltage or the output voltage by the resistors.
Is what you enter.

The normal driving means 7a synchronizes with the input voltage waveform from the rectification bridge 2 and the current flowing from the choke coil 10 through the FRD 11 to the smoothing capacitor 3 so that the input current waveform becomes a sine wave approximation. The power device 12 is turned on and off. The voltage adjusting means 7b varies the on / off time of the power device 12 so that the voltage value is set by the control unit 6 in accordance with the change in the output voltage detected by the output voltage detection circuit 14, and the output voltage is changed. Is to control.

As shown in FIG. 2, the abnormality detecting means is provided between the active filter control section 7 and the state detecting means 7c for detecting the state of the active filter 9, and between the active filter control section 7 and the control section 6. It is composed of a photocoupler 8a that constitutes the interface section 8. The state detecting means 7c detects whether or not the active filter 9 is abnormal according to the output voltage from the output voltage detecting circuit 14, and when the output voltage from the output voltage detecting circuit 14 decreases, the state detecting means 7c uses the active filter. 9 is judged to be abnormal or stopped, the photo coupler 8a is turned on,
An abnormality detection signal is transmitted to the control unit 6.

The control unit 6 controls each unit of the air conditioner based on the contents set by an operation unit (not shown) provided in the main body of the air conditioner.
It is a microcomputer including a ROM and the like.
The control unit 6 drives the inverter unit 4 via a drive circuit 16 as shown in FIG. 1, and an active filter drive unit that sends a control signal to the active filter control unit 7 to drive the active filter 9. And means for stopping the inverter unit 4 in response to an abnormality detection signal from the state detection unit 7c of the active filter control unit 7.

The control unit 6 also includes an output voltage detection circuit 14
When the output voltage from the active filter 9 is detected by the output voltage detection circuit 14 and the output voltage exceeds the set value and exceeds a certain voltage value, the electric compressor 5 is stopped or It is provided with an overvoltage protection unit that determines that an abnormality has occurred in the inverter unit 4 and stops the active filter 9.

Here, in general, the active filter controller 7 switches the power device 12 of the active filter 9 and is insulated from the controller 6. That is, as shown in FIG. 2, the control unit 6 and the active filter control unit 7 are configured to operate independently by the respective power sources 17 and 18, and exchange signals with each other by the photocouplers 8a and 8b. Is performed via the interface unit 8 composed of. In such a case, both power supplies 17 and 18 are activated, and the active filter control unit 7 receives the control signal from the control unit 6 to operate. However, if the active filter 9 has an abnormality, the state detecting means 7c turns on the photocoupler 8a to transmit an abnormality detection signal to the control unit 6, but an abnormality such as interruption of power supply to the active filter control unit 7 occurs. If it happens,
Since the photocouplers 8a and 8b are not turned on, the active filter control unit 7 does not transmit the abnormality detection signal to the control unit 6, and it is impossible to notify the control unit 6 of the abnormal state. Therefore, the inverter unit 4 cannot be stopped, and a problem occurs that the voltage applied to the electric compressor 5 is insufficient and the electric compressor 5 is locked.

Therefore, the abnormality detecting means always turns on the photocoupler 8a when the active filter control section 7 is in a normal state, that is, when the power supply 18 is supplied,
A low-level signal is always input to the abnormality detection port S of the control unit 6. On the other hand, when an abnormality such as interruption of power supply to the active filter control unit 7 occurs, the photocoupler 8a is turned off and a high level signal is input to the port S of the control unit 6. Further, even if the active filter control unit 7 is normal, when the state detection unit 7c detects an abnormality in the active filter 9, the photocoupler 8a is turned off and a high level signal is input to the port S of the control unit 6. It has become.

When a low level signal is input to the abnormality detection port S, the control section 6 determines that the active filter 9 and the active filter control section 7 are normal, and the control signal transmission port T outputs the signal. A high-level ON signal is transmitted to turn on the photocoupler 8b to perform an active filter driving function. Further, when a high level signal is input to the abnormality detection port S, it is determined that both or one of the active filter 9 and the active filter control unit 7 is in an abnormal state, and the inverter unit 4 is stopped. It is configured to perform a stop function.

In the above structure, when the start button is pressed by the operation unit of the air conditioner, the port T of the control unit 6 is pressed.
Sends a high level ON signal from the active filter control unit 7 to turn on the photocoupler 8b to drive the active filter 9 as shown in FIG. The part 4 is driven.

First, when the active filter 9 is driven, the AC voltage from the commercial power source 1 is full-wave rectified by the rectifying bridge 2 and input to the active filter 9.
At this time, the active filter control unit 7 turns on / off the power device 12 according to the control signal from the control unit 6 so that the output voltage of the active filter 9 becomes a set value,
The current flowing into the smoothing capacitor 3 via the choke coil 10 and FRD 11 is switched. Then
The input current has a sine waveform with the same phase as the input voltage waveform, and the output voltage from the active filter 9 is boosted to the set value. Then, the converted direct current is smoothed by the smoothing capacitor 3, and the smoothed direct current is supplied to the inverter unit 4. As a result, generation of higher harmonic current can be suppressed, power factor can be improved, and power source utilization efficiency can be improved.

On the other hand, after a certain time has passed after the active filter 9 is driven, the control section 6 sends a control signal to the inverter section 4 via the drive circuit 16 to switch the six transistors. Then, the direct current from the active filter 9 is chopped, a pseudo sine wave (PWM waveform) is applied to the electric compressor 5, the electric compressor 5 is driven, and the cooling operation or the heating operation of the air conditioner is started.

At this time, in the active filter controller 7, the output voltage detection circuit 14 causes the active filter 9 to operate.
Output voltage is constantly detected, and when the output voltage changes, the on / off time of the power device 12 is changed according to the change, and the output voltage is adjusted.

Further, the photo-coupler 8a is constantly turned on by the state detecting means 7c, a low level signal is input to the port S of the control section 6, and the control section 6 causes the active filter 9 or the active filter control section 7 to operate. When it is determined to be normal, normal driving operation is continued. Then, if an abnormality occurs in the active filter 9 or the active filter control unit 7, for example, if the power supply to the active filter control unit 7 is interrupted for some reason,
Both the photocouplers 8a and 8b of the interface section 8 are turned off, the active filter 9 is not driven, and there is a risk that the voltage applied to the electric compressor 5 will be insufficient and it will stop with a slight lock. Is turned off, a high level signal is input to the port S of the control unit 6, the control unit 6 determines that the active filter 9 or the active filter control unit 7 is in an abnormal state, and immediately turns on the inverter unit 4. Stop.

Further, the control section 6 constantly detects the output voltage from the active filter 9 by the output voltage detection circuit 14, and for example, when the electric compressor 5 is stopped or the inverter section 4 becomes abnormal, the output voltage is detected. Exceeds a set value and rises above a certain constant voltage value, the control unit 6 judges that it is in an abnormal state, transmits a low level off signal from the port T, turns off the photocoupler 8b, and turns off the active filter 9 To stop. When the active filter 9 or the inverter unit 4 stops due to an abnormality or the like, the LED or buzzer provided on the indoor unit side of the air conditioner notifies the user.

Then, when the stop button of the air conditioner is pressed or when the operation stop time by the timer is reached, the drive of the inverter unit 4 is stopped, and the drive of the active filter 9 is stopped after a lapse of a certain time after the stop. Then, the cooling operation or the heating operation of the air conditioner ends.

As described above, the control section 6 and the active filter control section 7 exchange signals and the like through the interface section 8 including the photocouplers 8a and 8b, and the active filter 9 or the active filter control section 7 has an abnormality. Occurs, the photocoupler 8a is turned off, and a high level signal indicating an abnormal state is input to the port S of the control unit 6. Therefore, even if an abnormality such as the interruption of the power supply to the active filter control unit 7 occurs, the control unit 6 is notified that the active filter 9 or the active filter control unit 7 is in the abnormal state. However, the control unit 6 does not control the active filter 9.

Moreover, when the active filter 9 or the active filter control unit 7 is detected to be abnormal or stopped, the inverter unit 4 is stopped, so that the electric compressor 5 can be prevented from being locked due to insufficient applied voltage. Further, when the output voltage of the active filter 9 exceeds the set value and exceeds a certain voltage value, it is detected that the inverter unit 4 is in an abnormal or stopped state and the active filter 9 is stopped. It is possible to prevent the destruction of the air conditioner 3 and the inverter unit 4, and to prevent a secondary failure of the air conditioner.

At the start of driving the active filter 9, the output voltage is boosted with respect to the input voltage, but the output voltage momentarily exceeds the set value due to the time delay of the feedback through the output voltage detection circuit 14. There is a case where the voltage is excessively boosted beyond a certain voltage value, or the output voltage becomes unstable even when the driving of the inverter unit 4 is started and stopped, so that the voltage is momentarily boosted to the certain voltage value. In this case, the control unit 6 may stop the active filter 9 by determining that the overvoltage protection function is in an abnormal state even though each unit is normally driven.
Therefore, as shown in FIG. 3, the control unit 6 is provided with an abnormality-free detection period A in which an abnormal state is not detected immediately after the operation of the inverter unit 4 is started or stopped, or immediately after the driving of the active filter 9 is started. ing.

As a result, the control section 6 does not perform the function of stopping the active filter 9 or the inverter section 4 even if a signal indicating an abnormal state by the abnormality detecting means is input during the abnormality-free period A. Therefore, it is possible to provide an air conditioner that can perform stable operation without erroneously stopping the active filter 9 or the inverter unit 4 despite normal operation.

The present invention is not limited to the above embodiment, and it goes without saying that many modifications and changes can be made to the above embodiment within the scope of the present invention. For example, in the above embodiment, the active filter control unit 7 is provided with the state detection unit 7c as the abnormality detection unit. However, the state detection unit 7c may be replaced by the control unit 6 or the active filter control unit 7.
Alternatively, it may be provided independently so as to be operated by a power source different from the above. Further, the state detecting means 7c is provided in the control unit 6, and the active filter 9 or the active filter control unit 7 is provided.
The state may be detected directly by the control unit 6.

[0040]

As is apparent from the above description, according to the inventions of claims 1 and 2, an abnormality occurs in the active filter or the active filter control section, and in particular, even if the power supply to the active filter control section is interrupted. A signal indicating an abnormal state is input to the control unit by the detection unit.
Therefore, it is surely notified that the active filter or the active filter control unit is in an abnormal state,
The control unit does not control the active filter in spite of the abnormal state.

According to the third aspect of the present invention, when the active filter or the active filter control section is detected to be abnormal or stopped, the inverter section is stopped.
It is possible to prevent the electric compressor from locking due to insufficient applied voltage. Further, when the abnormality or the stopped state of the inverter unit is detected, the active filter is stopped, so that it is possible to prevent the parts from being damaged due to the excessive boosting.
Therefore, a highly reliable air conditioner is realized without causing a secondary failure of the air conditioner.

According to the fourth aspect of the present invention, even if a signal indicating an abnormal state is input to the control unit during a certain period immediately after the inverter unit starts operation, immediately after operation stop, or immediately after the active filter starts driving, an abnormality occurs. Since the detection is not performed, even if the output voltage becomes unstable during this period, the active filter and the inverter unit are not accidentally stopped. Therefore, it is possible to provide an air conditioner capable of performing stable operation.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an inverter circuit of an air conditioner equipped with an active filter showing an embodiment of the present invention.

FIG. 2 is a configuration diagram of an interface unit between a control unit and an active filter control unit.

FIG. 3 is a timing chart showing the operation of the active filter and the inverter section and the boosting operation of the output voltage.

FIG. 4 is a diagram showing an input voltage waveform and an input current waveform in a capacitor input type inverter circuit.

[Explanation of symbols]

 4 Inverter section 5 Electric compressor 6 Control section 7 Active filter control section 9 Active filter 17, 18 Power supply A Abnormality non-detection period

Claims (4)

[Claims] 1. A means for rectifying an AC power source to convert it into a direct current, an inverter section for chopping the direct current and applying an AC voltage of a variable voltage variable frequency to an electric compressor, and an output frequency of the inverter section according to an air conditioning load. Control unit, an active filter that matches an input current with a waveform and a phase of an input voltage and outputs the same to the inverter unit, and an active filter control unit that drives the active filter based on a control signal from the control unit. An air conditioner comprising: an air conditioner provided with an abnormality detecting means for detecting and notifying an abnormal state of both or one of the active filter control unit and the active filter control unit. 2. The control unit and the active filter control unit are operated by individual power sources, and the abnormality detection unit inputs an abnormality detection signal to the control unit even when power supply to the active filter control unit is interrupted. The air conditioner according to claim 1, which is characterized in that. 3. The inverter unit is stopped when the active filter or the active filter control unit is abnormal or stopped, and the active filter is stopped when the inverter unit is abnormal or stopped. The air conditioner according to 1 or 2. 4. The control unit is set with a period during which an abnormal state is not detected immediately after the operation of the inverter unit is started or stopped, or immediately after the driving of the active filter is started. Air conditioner.