JP7380257B2 - air conditioner - Google Patents

Description

The present invention relates to an air conditioner, and more particularly, to failure detection of a heater provided in an outdoor unit.

Conventionally, a failure of, for example, a base heater in an air conditioner is detected by a change in the total current of the compressor of the outdoor unit and the base heater (see, for example, Patent Document 1). The base heater is attached to the bottom plate (base) of the outdoor unit, and heats the bottom plate to prevent drain water from freezing that occurs during defrosting operation during heating.
The outdoor unit of this air conditioner includes a compressor 101 that compresses refrigerant, a compressor drive circuit 102 that drives the compressor 101, a base heater 103 that generates heat when energized, and an AC power supply 106 that is applied to the base heater 103. A heater drive circuit 104 which is a switch to shut off, a current detection circuit 107 which detects the current supplied from the AC power supply 106, and a current signal which is the output of the current detection circuit 107 are inputted to control the compressor drive circuit 102. , a microcomputer 108 that controls the heater drive circuit 104 to apply/cut off the AC power supply 106 to the base heater 103.

The microcomputer 108 compares the current signal before the control of applying the AC power supply 106 to the heater drive circuit 104 with the current signal after the applied control while the compressor drive circuit 102 is driving the compressor 101. If the difference is not less than a certain value, the base heater 103 is not energized, and it is determined that the base heater 103 itself is disconnected or the heater drive circuit 104 is malfunctioning.

However, since the current consumption of the base heater is smaller than that of the compressor, there is a problem in that it is not possible to accurately detect whether or not the AC power supply is energized in the base heater. For example, in a domestic air conditioner, the current consumption when the compressor is operating at maximum capacity is 15 amperes or more. On the other hand, the current consumption of the base heater is about 0.4 ampere. Therefore, if you control the application of AC power to the base heater while the compressor is operating at maximum load, it is necessary to detect an increase in current consumption and confirm that the base heater is energized in order to determine a failure. However, in reality, current changes due to compressor load fluctuations and current changes due to energization of the AC power supply to the base heater coexist, making it impossible to accurately determine failure of the base heater or its drive circuit.

JP2006-292239A (paragraph numbers 0013-0015)

The present invention solves the above-mentioned problems, and even if control is performed to apply AC power to the heater while the compressor is operating, the heater may be disconnected or the heater cannot be driven to apply AC power to the heater. The purpose is to determine the failure of a circuit (switch).

In order to solve the above-mentioned problems, the invention according to claim 1 of the present invention has the following features:
a rectifier that rectifies input AC power and converts it into DC power; a booster that boosts and outputs the DC voltage output from the rectifier and improves the power factor; and a DC voltage output from the booster. an inverter section that converts and outputs the AC voltage into an AC voltage, a compressor driven by the inverter section, and outputs a voltage control signal to the boost section, and outputs a voltage control signal to the inverter section that converts the rotation speed of the compressor and the AC voltage. a heater to which the alternating current power is applied; a switch for applying/cutting off the alternating current power to the heater according to a drive signal output from the control section; and a drive for driving the switch. An air conditioner equipped with an outdoor unit having a circuit,
The outdoor unit is
an AC voltage detection unit that detects the AC voltage;
an alternating current detection unit that detects an alternating current flowing through the heater and the rectifier;
a power factor detection unit that calculates and outputs a power factor from the detected alternating current and the alternating voltage;
The apparatus is characterized by comprising a failure determination means for determining whether at least one of the heater, the switch, or the drive circuit is normal or abnormal based on the drive signal and the power factor.

By using the above means, according to the air conditioner according to the present invention, even if control is performed to apply AC power to the heater while the compressor is operating, the AC power is applied to the heater. /A break in the heater or a failure in the heater drive circuit can be determined by the change in power factor when the heater is de-energized.

FIG. 1 is a block diagram showing an embodiment of an air conditioner according to the present invention. It is an explanatory diagram explaining operation of the present invention. FIG. 2 is a table showing power factors depending on input current and base heater status, and an explanatory diagram showing conditions for determining normality/abnormality. FIG. 1 is a block diagram showing a conventional air conditioner.

Hereinafter, embodiments of the present invention will be described in detail as examples based on the accompanying drawings.

[Explanation of the entire air conditioner]
FIG. 1 is a block diagram showing an air conditioner 1 according to the present invention.
This air conditioner 1 includes an outdoor unit 40 connected to an AC power source 2, and an indoor unit 50 connected to the outdoor unit 40 through a communication line.

In addition, the outdoor unit 40 is connected to a rectifier 3 that rectifies the AC power source 2 and converts it into a DC power source, and a positive output terminal and a negative output terminal of the rectifier 3, and boosts and outputs the voltage of the input DC power source. The boost unit 4 and the positive output terminal and negative output terminal from which the DC voltage is outputted from the boost unit 4 are connected to the input terminal, respectively, and convert the input DC voltage to generate three-phase AC, and the compressor 7 The DC voltage is connected between the inverter unit 5 supplied to An alternating current detection unit that is arranged in series between the detection unit 6, one power line (N side) of the alternating current power supply 2, and one alternating current input terminal of the rectifier 3, and detects alternating current and outputs it as an alternating current signal. 8, a base heater 10 that is a heater that warms the bottom surface of the outdoor unit 40, and an outdoor unit control unit 20 that controls the outdoor unit 40. The alternating current detection section 8 detects the total alternating current of the alternating current flowing through the base heater 10 and the rectifier 3.

[Explanation of outdoor unit control section]
The outdoor unit control unit 20 drives a pair of power wires 9 connecting the two input ends of the rectifier 3 and the base heater 10, a relay 22 which is a switch connected in series to one of the power wires 9, and the relay 22. The drive circuit 24 outputs a voltage control signal that controls the booster 4 so that the voltage of the DC power output from the rectifier 3 becomes the target voltage, and also outputs a voltage control signal to the inverter 5 to control the rotation speed of the compressor 7. It outputs an inverter control signal that controls the magnitude of the three-phase AC voltage that drives the compressor 7, and outputs a heater drive signal (drive signal) that controls the opening and closing of the relay 22. A control unit 21 that controls the entire system, a power factor detection unit 30 that detects the power factor, and a failure of at least one of the base heater 10, relay 22, and drive circuit 24 based on the input heater drive signal and power factor. A failure determination section (failure determination means) 23 is provided for making determinations. Note that the failure determination unit 23 will be explained in detail later.

[Description of power factor detection section]
The power factor detection unit 30 includes an AC voltage detection unit 34, an active power calculation unit 31 that calculates active power, an apparent power calculation unit 32 that calculates apparent power, and a power factor calculation unit 33 that calculates power factor. We are prepared. The AC voltage detection unit 34 detects the instantaneous value of the input DC voltage signal (the detection signal of the voltage that has been full-wave rectified by the rectifier 3), and uses this instantaneous value as an AC voltage signal to communicate with the active power calculation unit 31 and the apparent power. It is output to the calculation unit 32. On the other hand, the active power calculating section 31 and the apparent power calculating section 32 each receive an alternating current signal from the alternating current detecting section 8 .

The active power calculation unit 31 calculates the active power consumed by the outdoor unit 40 from the input AC voltage signal and AC current signal. Specifically, the active power calculation unit 31 integrates the product of the instantaneous current and the instantaneous voltage for one second to calculate and output the active power. On the other hand, the apparent power calculation unit 32 calculates the apparent power supplied to the outdoor unit 40 from the input AC voltage signal and AC current signal. Specifically, the apparent power calculation unit 32 calculates and holds the effective value of the voltage from the peak voltage value of the input voltage using the AC voltage signal. Furthermore, the product of the value obtained by integrating the instantaneous current for 1 second and the effective value of the held voltage is output as apparent power. The power factor calculation unit 33 receives the active power and the apparent power, and calculates and outputs the power factor by dividing the active power by the apparent power.

[Description of failure determination unit]
The failure determination section 23 receives the power factor from the power factor calculation section 33 and also receives the heater drive signal from the control section 21 . The failure determination unit 23 constantly monitors changes in the power factor, and when the power factor exceeds a pre-stored determination threshold (for example, 83%) while the relay 22 is closed by the heater drive signal, Further, a state in which the power factor is less than the determination threshold value (83%) while the relay 22 is open is determined to be normal. In any other state, the failure determination section 23 determines that either the base heater 10, the relay 22, or the drive circuit 24 has failed, and outputs an error signal to the control section.

In this embodiment, when the control unit 21 is operating the compressor 7, the power factor is controlled to improve the power factor and approach the target power factor (for example, 90%), so the power factor remains within a certain range. controlled by. On the other hand, since the base heater 10 generates heat using a nichrome wire or the like, the power factor is 100%. Therefore, when the compressor 7 is in operation, if the relay 22 is closed at the same time and current flows through the base heater 10, the base heater 10 increases only the active power, so in the equation of power factor = active power / apparent power. The power factor increases. In other words, the power factor in the outdoor unit 20 is improved by further supplying current to the base heater 10 compared to when only the compressor 7 is operated. The failure determination unit 23 determines that the base heater 10, relay 22, and drive circuit 24 are all normal in this state.

FIG. 3(A) is an explanatory diagram of a table showing the power factor (%) depending on the input current and the energization/non-energization state of the base heater 10 when the compressor 7 is in operation, which was measured by experiment. The horizontal direction of this table indicates input current (effective value), and cases where this input current is 3 amperes, 5 amperes, 8 amperes, and 13 amperes are shown. On the other hand, the vertical direction represents the energized/de-energized state of the base heater 10, the power factor difference due to the energized/de-energized state, and the determination threshold for each input current. The determination threshold value for each input current is set to a value approximately in the middle of each power factor depending on energization/non-energization for each input current.

As shown in FIG. 3A, when the input current is constant, the power factor is larger when the base heater 10 is energized than when it is not energized. Further, the value of the difference decreases as the input current increases, but it is a value of 5% that makes it possible to determine whether or not there is a failure even when the input current is at the maximum (13 amperes). Therefore, by setting the threshold value to a value between the power factor when the base heater 10 is energized and when the base heater 10 is not energized, it can be determined whether or not current is flowing through the base heater 10. In this example, the power factor of 83%, which allows determination of whether or not there is a failure, is set as the determination threshold for each input current value, but the determination threshold is not limited to this, and the determination threshold for each input current in FIG. As shown in the column, more accurate determination can be made by changing the determination threshold for each input current according to the input current.

[Explanation of operation]
FIG. 2 is an explanatory diagram illustrating the operation of the present invention. In FIG. 2, the horizontal axis represents time, and the vertical axis represents (1) the state of the compressor 7, (2) the state of the booster 4, (3) the heater drive signal, and (4) the open/close state of the contacts of the relay 22. , (5) the state of the base heater 10, (6) the power factor value, and (7) the error signal. Further, the left side of FIG. 2 shows disconnection detection of the base heater 10, and the right side of FIG. 2 shows failure detection of the relay 22 or drive circuit 24. Note that t0 to t6 are times.

First, the operation of detecting disconnection of the base heater 10 will be explained using the left side diagram of FIG.
At time t0, the air conditioner 1 is in a thermo-off (operation stopped) state. In this case, the compressor 7 and booster 4 are stopped while the outdoor unit 40 is powered on, and the contacts of the relay 22 are open and power is not supplied to the base heater 10. ing. At this time, since the booster section 4 is in a non-operating state, the power factor is not improved, so the power factor is approximately 60%.

Then, at time t1, when an instruction to start the operation of the compressor 7 is transmitted from the indoor unit 50 to the control unit 21, the control unit 21 starts increasing the pressure by the pressure boosting unit 4, and starts operating the compressor 7 ( compressor operating status). The control unit 21 causes the boost unit 4 to start boosting the voltage and at the same time starts an operation for improving the power factor. The input current at this time is about 8 amperes, and the power factor increases from about 60% before the compressor 7 starts operating to 79%. Since the relay 22 is in the "open" state and the current power factor (79%) is less than the determination threshold (83%), the failure determination unit 23 determines that it is "normal" and does not output an error signal. Note that the input current (effective value) at this time is 8 amperes.

Then, at time t2, when the control unit 21 instructs "close" with the heater drive signal, the relay 22 becomes "closed" and the AC power source 1 is supplied to the base heater 10. As described above, when the base heater 10 is energized, the power factor is improved, and the power factor (79%) changes to the power factor (85%). The failure determination unit 23 outputs an error signal in order to determine that it is "normal" because the "close" instruction is given by the heater drive signal and the current power factor (85%) is greater than the determination threshold (83%). No output.

In this state, if the base heater 10 is disconnected due to a failure at time t3, the power factor (85%) changes to the power factor (79%). Since "close" is instructed by the heater drive signal and the power factor (79%) is less than the determination threshold (83%), the failure determination unit 23 determines that it is "abnormal" and outputs an error signal. . The control unit 21 to which this error signal has been input transmits this "abnormal" state to the indoor unit 50, and the indoor unit 50 notifies the user of the error message.

Next, the operation of detecting a failure of the relay 22 will be explained using the right side diagram of FIG.
At time t4, the air conditioner 1 is in the thermo-on state. The control unit 21 is increasing the pressure in the pressure increasing unit 4, and the compressor 7 is also in operation. Since the control unit 21 also performs an operation to improve the power factor while boosting the voltage in the boosting unit 4, the power factor is 85%. The failure determination unit 23 determines that the state is "normal" and issues an error signal because "close" is instructed by the heater drive signal and the current power factor (85%) is greater than or equal to the determination threshold (83%). is not output. Note that the input current (effective value) at this time is 8 amperes.

In this state, at time t5, the control unit 21 turns the heater drive signal "open" to stop power supply to the base heater 10. In this case, for example, when the contacts of the relay 22 are welded, the contacts should be "open" if the relay 22 is normal, but the contacts do not "open" and remain "closed". Therefore, power remains supplied to the base heater 10, and the power factor remains unchanged at 85%.

Since "open" is instructed by the heater drive signal and the current power factor (85%) is equal to or higher than the determination threshold (83%), the failure determination unit 23 determines that it is "abnormal" and sends an error signal. Output. The control unit 21 to which this error signal has been input transmits this "abnormal" state to the indoor unit 50, and the indoor unit 50 notifies the user of the error message.

Note that it is possible to detect not only a failure in which the contacts of the relay 22 are welded, but also a case in which the relay 22 fails and the contacts do not close.
If the current power factor is less than the determination threshold (83%) when the heater drive signal changes from an "open" instruction to a "close" instruction, the failure determination unit 23 determines that it is "abnormal" and sends an error signal. Output. This occurs when the winding of the relay 22 is disconnected or the driving element of the relay 22 is out of order.

The above determination conditions will be explained using FIG. 3(B). FIG. 3(B) is an explanatory diagram showing conditions for determining whether the relay 22 and the drive circuit 24 are normal or abnormal. In FIG. 3(B), from left to right, states are shown in which "the heater drive signal instructs to open" and "the heater drive signal instructs to close". Also, from top to bottom, states of "power factor is less than the determination threshold" and "power factor is greater than or equal to the determination threshold" are shown. The items shown in each state indicate the normality/abnormality of any one part of the base heater 10, the relay 22, or the drive circuit 24.

While the heater drive signal is instructing to close the relay 22, the power factor is greater than or equal to the determination threshold, and while the heater drive signal is instructing to open the relay 22, the power factor is less than the determination threshold. is normal. Also, while the heater drive signal is instructing to open the relay 22, the power factor is greater than the determination threshold, and while the heater drive signal is instructing to close the relay 22, the power factor is determined to be higher than the determination threshold. A state where the value is less than the threshold value is abnormal.
In other words, if power is applied to the base heater 10, the power factor will be improved compared to when power is not applied; otherwise, the base heater 10 may be disconnected, the relay 22 may be broken, or Alternatively, it is determined that the drive circuit 24 has failed.

[Effects of the present invention]
As explained above, even when the compressor 7 is operating, a break in the base heater 10 or a failure in the drive circuit 24 or relay 22 can be determined based on the state of the heater drive signal and the power factor value. can do.

1 Air conditioner 2 AC power supply 3 Rectifier 4 Boosting section 5 Inverter section 6 DC voltage detection section 7 Compressor 8 AC current detection section 9 Power line 10 Base heater (heater)
20 Outdoor unit control section 21 Control section 22 Relay (switch)
23 Failure determination unit (failure determination means)
24 Drive circuit 30 Power factor detection section 31 Active power calculation section 32 Apparent power calculation section 33 Power factor calculation section 34 AC voltage detection section 40 Outdoor unit 50 Indoor unit

Claims (2)

a rectifier that rectifies input AC power and converts it into DC power; a booster that boosts and outputs the DC voltage output from the rectifier and improves the power factor; and a DC voltage output from the booster. an inverter section that converts and outputs the AC voltage into an AC voltage, a compressor driven by the inverter section, and outputs a voltage control signal to the boost section, and outputs a voltage control signal to the inverter section that converts the rotation speed of the compressor and the AC voltage. a heater to which the alternating current power is applied; a switch for applying/cutting off the alternating current power to the heater according to a drive signal output from the control section; and a drive for driving the switch. An air conditioner equipped with an outdoor unit having a circuit,
The outdoor unit is
an AC voltage detection unit that detects the AC voltage;
an alternating current detection unit that detects an alternating current flowing through the heater and the rectifier;
a power factor detection unit that calculates and outputs a power factor from the detected alternating current and the alternating voltage;
An air conditioner comprising: failure determination means for determining whether at least one of the heater, the switch, or the drive circuit is normal or abnormal based on the drive signal and the power factor. The failure determination means includes:
A threshold for determining a value between the power factor when the compressor is in operation and the AC power is not applied to the heater and the power factor when the AC power is applied to the heater. It is stored in advance as
If the drive signal is an instruction to close the switch and the power factor is greater than or equal to the determination threshold, or if the drive signal is an instruction to open the switch and the power factor is If it is less than the judgment threshold, it is judged as normal,
If the drive signal is an instruction to open the switch and the power factor is greater than or equal to the determination threshold, or if the drive signal is an instruction to close the switch and the power factor is The air conditioner according to claim 1, wherein the air conditioner is determined to be abnormal if it is less than a determination threshold.

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