JP2018119701A - Air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To continue an operation of a compressor as long as possible when momentary voltage drop occurs, without increasing the capacity of a smoothing capacitor provided at a DC power supply for supplying a voltage to the compressor.SOLUTION: An air conditioner includes: a DC power supply 18 including a rectifier 8 in which an AC power supply 2 is inputted and a smoothing capacitor 9; an inverter 14 in which a DC voltage outputted by the rectifier 8 is inputted; a compressor 15 driven by the inverter 14; an inverter control part 16 for controlling the inverter 14; an AC voltage detection part 5 for detecting an input voltage of the AC power supply 2 and for outputting an AC voltage value; a control part 17 for outputting a rotational frequency command value which instructs the rotational frequency of the compressor 15 to the inverter control part 16; and momentary voltage drop processing means 20 for outputting the rotational frequency command value for lowering the rotational frequency of the compressor 15 when the AC voltage has dropped to a momentary drop threshold value which is a predetermined voltage value or lower.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an air conditioner, and more particularly to a control method for continuing operation as much as possible when an instantaneous voltage drop occurs.

  Conventionally, the capacity of a smoothing capacitor provided in a DC power source supplied to a compressor is determined so that the operation of the air conditioner is not interrupted as much as possible even if an instantaneous voltage drop occurs during operation of the compressor. Since this compressor consumes a larger current than other parts of the air conditioner, a large-capacity capacitor is required. However, in consideration of cost, there is a restriction that a large-capacity capacitor cannot be adopted.

  For this reason, the capacity | capacitance of this smoothing capacitor is suppressed to the capacity | capacitance of the grade which does not interrupt | operate operation even if the instantaneous voltage drop of about 10-20 milliseconds. When the operation of the compressor is temporarily suspended due to the instantaneous voltage drop, a waiting time for restarting the operation of about 3 minutes occurs until the refrigerant pressure in the air conditioner is balanced. During this time, the room temperature changes to affect the comfort of the user. Therefore, it is desirable that the operation can be continued as much as possible even if an instantaneous voltage drop occurs.

As a method for coping with the continuation of the operation of the air conditioner when such an instantaneous voltage drop occurs, there is a technique disclosed in Patent Document 1.
This document describes that the phase loss time caused by the instantaneous voltage drop is measured, and the heater, fan motor, and compressor are sequentially stopped as the phase loss time elapses. In other words, the operation is continued as much as possible during the above-described period of occurrence of the instantaneous voltage drop by sequentially shutting off the load circuit as the period of the instantaneous voltage drop increases.

  However, in the method of this document, since the phase loss time is measured as a method for detecting the instantaneous voltage drop, for example, in the case of an air conditioner operating with an AC power supply of 50 Hz, at least the detection of the instantaneous voltage drop is required. One cycle of the AC power supply, that is, 20 milliseconds is required. Furthermore, when the power supply of the heater or fan motor is disconnected by the relay from the detection of the instantaneous voltage drop, the mechanical delay time of the relay is generated. After about 10 to 20 milliseconds have elapsed, the load is actually reduced. That is, 30 to 40 milliseconds are required from the occurrence of the instantaneous voltage drop until the load is reduced. As described above, the capacity is high (expensive) in order to maintain the operation of the air conditioner for at least this time. A smoothing capacitor was required.

On the other hand, as a method for detecting an instantaneous voltage drop, there is a method for detecting when the phase loss time has elapsed for a predetermined time as described above or when the voltage of the smoothing capacitor has become equal to or lower than the predetermined voltage. The threshold for determination by such a method is determined under the worst condition with a margin.
For example, the air conditioning operation is performed for a predetermined time, which is the generation time of the instantaneous voltage drop when the smoothing capacitor decreases in capacity due to aging, the maximum load, and the AC voltage is the lower limit of the operating voltage range of the air conditioner. The capacity of the smoothing capacitor that can be used is determined.

  However, the instantaneous voltage drop that occurs during actual air conditioning operation does not necessarily occur under the worst conditions, and the AC voltage may be the upper limit of the operating voltage range, or the load for air conditioning operation may be light. In such a case, the air conditioning operation stop may be determined using the threshold value determined under the worst condition even when there is a margin for continued operation. In other words, in practice, due to the AC voltage just before the momentary voltage drop occurs and the size of the load, even though the time during which air conditioning operation can be performed with the charge stored in the smoothing capacitor changes, the operation is stopped under certain conditions, Even if the air-conditioning operation could be continued, the operation was sometimes stopped.

JP-A-9-222256 (page 3-4, FIG. 1)

  The present invention solves the above-described problems, and allows air to continue the operation of the compressor as much as possible when an instantaneous voltage drop occurs without increasing the capacity of the smoothing capacitor provided in the DC power supply that supplies voltage to the compressor. The purpose is to provide a harmony machine.

In order to solve the above problems, the present invention according to claim 1 of the present invention provides:
A DC power supply including a rectifier and a smoothing capacitor to which AC power is input;
An inverter to which a DC voltage output from the rectifier is input;
A compressor driven by the inverter;
An inverter control unit for controlling the inverter;
An AC voltage detector that detects an input voltage of the AC power supply and outputs an AC voltage value;
A control unit for outputting a rotation speed command value for instructing the rotation speed of the compressor to the inverter control unit;
And an instantaneous voltage reduction processing means for outputting the rotational speed command value for reducing the rotational speed of the compressor when the AC voltage is reduced to a threshold value that is a predetermined voltage value or less. And

The invention according to claim 2 of the present invention is
The air conditioner further includes a load device that operates using the DC voltage,
The instantaneous voltage drop processing means stops the operation of the load device when the AC voltage drops below the instantaneous drop threshold.

  By using the above means, the air conditioner according to the present invention operates the compressor when an instantaneous voltage drop occurs without increasing the capacity of the smoothing capacitor provided in the DC power supply for supplying voltage to the compressor. Can continue as long as possible.

It is a block diagram of the outdoor unit which shows the Example of the air conditioner by this invention. It is a block diagram which shows an instantaneous voltage reduction process part. It is explanatory drawing explaining operation | movement of the outdoor unit by this invention. (No shutdown) It is another explanatory drawing explaining operation | movement of the outdoor unit by this invention. (Operation stop due to overcurrent) It is another explanatory drawing explaining operation | movement of the outdoor unit by this invention. (Operation stopped due to low voltage)

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail as examples based on the attached drawings.

  The outdoor unit 1 includes an L terminal 3 to which a non-grounded power line of the AC power supply 2 is connected, an N terminal 4 to which a grounded power line of the AC power supply 2 is connected, a relay 6, a reactor 7, and a rectifier. 8, a smoothing capacitor 9, an inverter 14, a compressor 15 driven by the inverter 14, an AC voltage detection unit 5, a DC voltage detection unit 12, a load current detection unit 13, a fan motor 11, and a fan motor The fan motor drive part 10 which drives 11 is provided.

  In the outdoor unit 1, the relay 6 and the reactor 7 are connected in series between the L terminal 3 and one input of the rectifier 8, and the N terminal 4 and the other input of the rectifier 8 are connected. Further, the positive electrode of the rectifier 8 is connected to the positive input of the inverter 14, and the load current detection unit 13 is connected in series between the negative electrode of the rectifier 8 and the negative input of the inverter 14.

  An AC voltage detection unit 5 that measures an instantaneous voltage of the AC power supply 2 between the L terminal 3 and the N terminal 4 and converts the measured value into an effective value is output between the positive terminal and the negative terminal of the rectifier 8. The smoothing capacitor 9, the fan motor drive unit 10, and the DC voltage detection unit 12 are connected to each other. The load current detection unit 13 uses the detected load current as a load current value, the AC voltage detection unit 5 uses the detected voltage as an AC voltage value (effective value), and the DC voltage detection unit 12 uses the detected voltage as a DC voltage value. Respectively. The rectifier 8 and the smoothing capacitor 9 constitute a DC power source 18.

  The outdoor unit 1 also includes an inverter control unit 16 that controls the inverter 14, an instantaneous voltage reduction processing unit (instantaneous voltage reduction processing means) 20, and a control unit 17 that controls the entire outdoor unit 1. The control unit 17 outputs to the instantaneous voltage drop processing unit 20 a relay command signal for controlling the relay 6, a fan motor command signal for controlling the fan motor driving unit 10, and a rotational speed command value for instructing the rotational speed of the compressor 15. doing.

  The instantaneous voltage drop processing unit 20 outputs a relay control signal to the relay 6 and the control unit 17, a fan motor control signal to the fan motor driving unit 10, and a rotation speed instruction value to the inverter control unit 16. On the other hand, the AC voltage value, the DC voltage value, and the load current value are input to the instantaneous voltage drop processing unit 20 and the control unit 17, respectively. When the instantaneous voltage drop has not occurred, the instantaneous voltage drop processing unit 20 outputs each control signal inputted from the control unit 17 as it is. When the instantaneous voltage drop occurs, the instantaneous voltage drop described later in detail. Each control signal corresponding to is output.

Next, the configuration of the instantaneous voltage drop processing unit 20 will be described using the block diagram of the instantaneous voltage drop processing unit 20 shown in FIG.
The instantaneous voltage drop processing unit 20 receives an AND circuit 30 that receives a relay command signal at one input terminal, an AND circuit 31 that receives a fan motor command signal at one input terminal, and an AC voltage value. An instantaneous voltage drop detection unit 21, a DC voltage drop detection unit 22 to which a DC voltage value is input, an overcurrent detection unit 23 to which a load current value is input, and a rotation speed at which the input rotation speed command value is stored A command value storage unit 25, a minimum rotation value storage unit 24, a rotation speed command value switching unit 26, an OR circuit 27, a knot circuit 28, and a knot circuit 29 are provided.

  The output terminal of the instantaneous voltage drop detection unit 21 is connected to the input terminal of the knot circuit 29, the selection terminal of the rotation speed command value switching unit 26, the permission terminal of the overcurrent detection unit 23, and the permission terminal of the DC voltage drop detection unit 22, respectively. The voltage sag occurrence detector 21 outputs a voltage sag detection signal to these terminals. The knot circuit 29 inverts the inputted instantaneous drop detection signal and outputs the inverted signal to the other input terminal of the AND circuit 31, and the AND circuit 31 outputs a fan motor control signal. Note that, when a high level instantaneous voltage drop detection signal is input to the respective permission terminals of the overcurrent detection unit 23 and the DC voltage drop detection unit 22, the respective units start to operate. Further, when a low level instantaneous drop detection signal is input to each permission terminal, each unit stops operating, and a low level signal is output from each output terminal.

  The DC voltage drop detection unit 22 outputs a DC voltage drop signal to one input terminal of the OR circuit 27, the overcurrent detection unit 23 outputs an overcurrent detection signal to the other input terminal of the OR circuit 27, and the OR circuit 27 Outputs a relay opening signal to the knot circuit 28, and the knot circuit 28 inverts the inputted relay opening signal and outputs it to the other input terminal of the AND circuit 30. The AND circuit 30 outputs a relay control signal.

  On the other hand, the minimum rotation value storage unit 24 stores the minimum rotation value that can be operated by the compressor 15, and the rotation speed command value storage unit 25 stores the rotation speed command value of the compressor 15. The value is output to the rotational speed command value switching unit 26, and the rotational speed command value switching unit 26 selects one of the input values based on the instantaneous drop detection signal, and outputs the selected value as the rotational speed command value.

  Next, the operation of the instantaneous voltage drop processing unit 20 will be described. When the outdoor unit 1 is in an air conditioning operation, both the relay command signal and the fan motor command signal are at a high level (the relay 6 is closed and the fan motor 11 is rotated). On the other hand, when the input AC voltage value (effective value) exceeds a predetermined voltage drop threshold (184 V), the voltage drop detection unit 21 outputs a voltage drop detection signal at a low level (no instantaneous voltage drop has occurred). The AND circuit 31 outputs the fan motor control signal at a high level.

  On the other hand, the DC voltage drop detection unit 22 stops the DC voltage drop detection function because the instantaneous drop detection signal is input at a low level. For this reason, the DC voltage drop signal is output at a low level (no DC voltage drop occurs). In addition, the overcurrent detection unit 23 stops the overcurrent detection function because the instantaneous drop detection signal is input at a low level. For this reason, the overcurrent detection unit 23 outputs an overcurrent detection signal at a low level (overcurrent has not occurred). Since the input DC voltage drop signal and the overcurrent detection signal are both at the low level, the OR circuit 27 outputs the relay open signal at the low level. The knot circuit 28 to which the relay opening signal is input outputs a high level signal to the other input terminal of the AND circuit 30. As a result, the AND circuit 30 outputs a high level (relay 6 is closed) relay control signal. To do.

Further, since the instantaneous drop detection signal is at a low level, the rotation speed command value switching unit 26 selects the rotation speed command value from the input minimum rotation value and rotation speed command value and outputs it as the rotation speed instruction value. .
As described above, when the instantaneous voltage drop does not occur, the instantaneous voltage drop processing unit 20 to which the relay command signal, the fan motor command signal, and the rotation speed command value output from the control unit 17 are input corresponds to these. The relay control signal, fan motor control signal, and rotation speed instruction value are output. For this reason, the control part 17 controls the relay 6, the fan motor 11, and the inverter 14 as it instruct | indicated.

  On the other hand, when the input voltage value falls below the threshold value, the voltage drop detection detector 21 outputs a voltage drop detection signal at a high level (a voltage drop occurs), and the AND circuit 31 controls the fan motor. Output signal at low level. As a result, the rotation of the fan motor 11 stops. At the same time, the rotational speed command value switching unit 26 switches the output rotational speed instruction value from the input rotational speed command value to the minimum rotational numerical value and outputs it because the instantaneous drop detection signal has changed from the low level to the high level. For this reason, the rotational speed of the compressor 15 gradually decreases toward the minimum rotational numerical value.

  Further, the voltage across the smoothing capacitor 9 (DC voltage value) also decreases as time elapses from the moment when the instantaneous voltage drop occurs. For this reason, the inverter control unit 16 tries to maintain the rotation speed of the compressor 15, and the load current increases in order to gradually increase the ON time of a switching element (not shown) in the inverter 14.

  If the generation period of the instantaneous voltage drop is further increased, the overcurrent detection unit 23 changes the overcurrent detection signal from the low level to the high level (overcurrent generation) when the load current value becomes equal to or greater than the load current threshold. Alternatively, the DC voltage drop detection unit 22 changes the DC voltage drop signal from a low level to a high level (DC voltage drop occurs) when the DC voltage value falls below a predetermined power-off threshold (220 volts).

  The OR circuit 27 changes the relay open signal from low level to high level (relay 6 is opened) when either the overcurrent detection signal or the DC voltage drop signal becomes high level. For this reason, since the output of the knot circuit 28 becomes a low level, the AND circuit 30 changes the relay control signal from the high level to the low level to open the contact of the relay 6 (disconnect the circuit). For this reason, the outdoor unit 1 stops the air conditioning operation.

  Next, the control for continuing the operation even when the instantaneous voltage drop occurs will be described with reference to FIG. The horizontal axis in FIG. 3 is time. 3, FIG. 3 (1) is an AC voltage (effective value), FIG. 3 (2) is a DC voltage, FIG. 3 (3) is a load current, and FIG. 3 (4) is a relay command signal. 3 (5) is a fan motor command signal, FIG. 3 (6) is a rotation speed command value, FIG. 3 (7) is an overcurrent detection signal, FIG. 3 (8) is a DC voltage drop signal, 3 (9) shows the rotational speed of the compressor 15, FIG. 3 (10) shows the instantaneous drop detection signal, FIG. 3 (11) shows the rotational speed indication value, FIG. 3 (12) shows the relay control signal, Reference numeral 3 (13) denotes a fan motor control signal. Note that t0 to t11 are times.

In FIG. 3, since the outdoor unit 1 is in an air conditioning operation stop state at t0, the control unit 17 outputs the relay command signal and the fan motor command signal at a low level, and outputs the rotation speed command value at 0 rpm. ing. Further, since the AC voltage value is 230 volts, the instantaneous voltage drop detection unit 21 outputs the instantaneous voltage drop detection signal at a low level (no instantaneous voltage drop has occurred) at t0.
Note that the DC voltage value is 0 volt below the power-off threshold (220 volts) at t0, but the DC voltage drop detection unit 22 has stopped functioning because the input instantaneous drop detection signal is at a low level. The DC voltage drop detection unit 22 outputs a DC voltage drop signal at a low level at t0.

  In order to start the air conditioning operation, the control unit 17 sets the relay command signal to a high level (closed) at t1. Next, in order to rotate the fan motor 11, the control unit 17 sets the fan motor command signal to a high level (ON) at t2. At the same time, in order to rotate the compressor 15, 2000 rpm is output as the rotation speed command value. For this reason, the inverter control unit 16 is driven to gradually increase the rotational speed of the compressor 15, and after reaching the rotational speed instructed at t3, control is performed so as to maintain this rotational speed. The load current gradually increases corresponding to the increase in the rotational speed of the compressor 15 and reaches 10 amperes at t3.

  Note that the AC voltage is 230 volts (rated voltage) and the DC voltage is 320 volts at the time point t3, but an instantaneous voltage drop of the AC voltage occurs thereafter, and the instantaneous voltage drop threshold (184) is reached when the AC voltage is t4. Bolt) has fallen below. For this reason, the voltage drop detection unit 21 outputs a voltage drop detection signal from a low level to a high level (while an instantaneous voltage drop is occurring). For this reason, the AND circuit 31 outputs the fan motor control signal from the high level to the low level (stop of the fan motor 11), and as a result, the fan motor 11 stops.

  The overcurrent detection unit 23 to which the instantaneous drop detection signal is input starts monitoring the load current value, and the rotation speed command value switching unit 26 replaces the input rotation speed command value (2000 rpm) with a minimum rotation value ( 200 rpm) is output to the inverter control unit 16 as the rotation speed instruction value. As a result, after t4, the inverter control unit 16 gradually decreases the rotational speed in order to set the rotational speed of the compressor 15 maintained at 2000 rpm to 200 rpm.

  On the other hand, since the AC voltage decreased at t4, the DC voltage also gradually decreased. When the AC voltage decreased to 150 volts, which is the lower limit peak of the instantaneous voltage decrease, the DC voltage also decreased to 230 volts at t5. The inverter control unit 16 was able to maintain the rotation of the compressor 15 at 2000 rpm and the load current at 10 amperes at t4. However, since the DC voltage gradually decreased, the load current gradually increased correspondingly. ing. As a result, the load current increases to 14 amperes at t5, but the decrease in the DC voltage has almost stopped decreasing at time t5. For this reason, the inverter control part 16 outputs the instruction | indication which reduces the applied voltage to the compressor 15 to the inverter 14 corresponding to the rotation speed reduction of the compressor 15, and load current reduces gradually after t5.

  After the time t5, when the AC voltage gradually increases and exceeds the voltage sag threshold at t7, the voltage sag detector 21 outputs the voltage sag detection signal from the high level to the low level. The inverter control unit 16 reduces the rotational speed of the compressor 15 to 1000 rpm at t7, but the rotational speed command value switching unit 26 to which the low-level instantaneous voltage drop detection signal is input replaces the minimum rotational numerical value with the rotational speed command. In order to output the rotational speed command value (2000 rpm) stored in the value storage unit 25 as the rotational speed instruction value, after t7, the inverter control unit 16 increases the rotational speed of the compressor 15 so that the instructed 2000 rpm is obtained. To control.

On the other hand, since the instantaneous voltage drop detection signal becomes low level at t7, the AND circuit 31 outputs the fan motor control signal from low level to high level, so that the operation of the fan motor 11 is resumed. The inverter control unit 16 increases the rotation speed of the compressor 15 to the instructed 2000 rpm, and controls to maintain this rotation after t11. At t11, the AC voltage and DC voltage are restored to the voltage before the instantaneous voltage drop occurs.
As described above, even when the instantaneous voltage drop occurs in the outdoor unit 1, the charge accumulated in the smoothing capacitor 9 can be reduced by temporarily stopping the fan motor 11 or reducing the rotational speed of the compressor 15. Consumption can be suppressed, and as a result, the air-conditioning operation can be continued without stopping.

  Next, the operation of the instantaneous voltage drop processing unit 20 when the rotation speed of the compressor 15 is relatively high, that is, when the load is heavy will be described with reference to FIG.

  The horizontal axis in FIG. 4 is time. 4, (1) is the AC voltage (effective value), FIG. 4 (2) is the DC voltage, FIG. 4 (3) is the load current, and FIG. 4 (4) is the relay command signal. 4 (5) is a fan motor command signal, FIG. 4 (6) is a rotation speed command value, FIG. 4 (7) is an overcurrent detection signal, FIG. 4 (8) is a DC voltage drop signal, 4 (9) shows the rotational speed of the compressor 15, FIG. 4 (10) shows the instantaneous drop detection signal, FIG. 4 (11) shows the rotational speed instruction value, FIG. 4 (12) shows the relay control signal, Reference numeral 4 (13) denotes a fan motor control signal. Note that t20 to t30 are times.

  In FIG. 4, the power-on by closing the relay 6 and the start of the operation of the compressor 15 are the same as those in FIG. 3, so the explanation from t20 to t22 in FIG. 4 corresponding to t0 to t2 in FIG. Is omitted. However, at t22, the controller 17 sets the rotation speed command value to 2500 rpm instead of 2000 rpm in the case of FIG. For this reason, the inverter control part 16 is raising the compressor 15 to 2500 rpm, and is performing control which maintains this rotation speed after t23.

  After that, when an instantaneous voltage drop occurs and the AC voltage becomes equal to or lower than the threshold value for voltage drop (184 volts) at t24, the voltage drop detection detector 21 changes the voltage drop detection signal from low level to high level (while instantaneous voltage drop is occurring). Output. For this reason, the AND circuit 31 outputs the fan motor control signal from the high level to the low level, and as a result, the fan motor 11 stops.

  The overcurrent detection unit 23 to which this instantaneous drop detection signal is input starts monitoring the load current value. The rotation speed command value switching unit 26 outputs the minimum rotation value (200 rpm) to the inverter control unit 16 as the rotation speed instruction value instead of the input rotation speed command value (2500 rpm). As a result, after t24, the inverter control unit 16 gradually decreases the rotational speed in order to set the rotational speed of the compressor 15 maintained at 2500 rpm to 200 rpm.

  On the other hand, the AC voltage continues to decrease after t24 and decreases to about 150 volts at t25. Correspondingly, after t24, the DC voltage also gradually decreases to 230 volts at t25. Further, the inverter control unit 16 was able to maintain the rotation of the compressor 15 at 2500 rpm and the load current at 12 amperes at t24, but since then the DC voltage has gradually decreased, the rotation speed is maintained accordingly. The load current gradually increases to perform the control.

  As a result, the load current increases to the overcurrent threshold (15 amperes) or more at t25. As a result, the overcurrent detection unit 23 outputs the overcurrent detection signal from the low level to the high level (overcurrent generation). Therefore, since the OR circuit 27 outputs the relay open signal from the low level to the high level (relay 6 is opened), the AND circuit 30 outputs the relay control signal at the low level, and the relay 6 is opened at t25. Become.

  For this reason, the rotation speed of the compressor 15 that has decreased to 2000 rpm at t25 continues to rotate due to inertia, and then stops at t26. On the other hand, since the control unit 17 monitors the relay control signal, the instantaneous voltage drop processing unit 20 opens the relay 6 when the relay command signal instructed to close is different from the input relay control signal. In preparation for the restart of the compressor 15, the relay command signal and the fan motor command signal are output at a low level, and the rotation speed command value is set at 0 rpm.

  Since the relay 6 is opened at t25 and the load is rapidly reduced, the voltage across the smoothing capacitor 9 once rises and then gradually decreases to 0 volt at t30. Further, since the DC voltage value becomes equal to or lower than the power-off threshold (220 volts) at t27, the DC voltage drop detection unit 22 outputs the DC voltage drop signal from the low level to the high level (DC voltage drop occurs) at t27.

  Then, after the time t25, when the AC voltage gradually increases and exceeds the voltage sag threshold at t28, the voltage sag occurrence detection unit 21 outputs the voltage sag detection signal from the high level to the low level. For this reason, the rotational speed command value switching unit 26 switches the rotational speed command value from the minimum rotational numerical value (200 rpm) to the stored rotational speed command value (0 rpm) and outputs it. Further, since the detection operation of the DC voltage drop detection unit 22 to which the low level instantaneous drop detection signal is input at t28 is prohibited, the DC voltage drop signal is output from the high level to the low level.

  As described above, even if the generation period and voltage drop of the instantaneous voltage drop described with reference to FIG. 3 are the same, the air conditioning operation cannot be continued when the load on the compressor 15 is heavy as shown in FIG. However, the operation can be stopped as overcurrent protection before the components of the inverter 14 are destroyed. In other words, even if an instantaneous voltage drop occurs, if the load is heavy, the air-conditioning operation can be continued as long as possible without destroying the parts, and conversely, if the load is light, the air-conditioning operation can be performed without stopping the operation. Can continue.

  Next, the case where the voltage drop due to the instantaneous voltage drop is larger than that in FIG. 3 will be described with reference to FIG. In addition, since the start operation | movement of an air conditioning driving | operation is the same as the case of FIG. 3, description is abbreviate | omitted.

  The horizontal axis in FIG. 5 is time. In the vertical axis of FIG. 5, FIG. 5 (1) shows the AC voltage (effective value), FIG. 5 (2) shows the DC voltage, FIG. 5 (3) shows the load current, and FIG. 5 (4) shows the relay command signal. 5 (5) is a fan motor command signal, FIG. 5 (6) is a rotation speed command value, FIG. 5 (7) is an overcurrent detection signal, FIG. 5 (8) is a DC voltage drop signal, FIG. 5 (9) shows the rotation speed of the compressor 15, FIG. 5 (10) shows the instantaneous drop detection signal, FIG. 5 (11) shows the rotation speed instruction value, FIG. 5 (12) shows the relay control signal, Reference numeral 5 (13) denotes a fan motor control signal. Note that t40 to t49 are times.

In FIG. 5, since the power-on by closing the relay 6 and the start of the operation of the compressor 15 are the same as in the case of FIG. 3, the description up to t <b> 44 in FIG.
When the AC voltage becomes equal to or lower than the voltage sag threshold (184 volts) at t44, the voltage sag detector 21 outputs the voltage sag detection signal from low level to high level (momentary voltage drop is occurring). For this reason, the AND circuit 31 outputs the fan motor control signal from the high level to the low level, and as a result, the fan motor 11 stops.

  The overcurrent detection unit 23 to which this instantaneous drop detection signal is input starts monitoring the load current value. Further, the rotation speed command value switching unit 26 outputs the minimum rotation value (200 rpm) to the inverter control unit 16 as a rotation speed instruction value instead of the input rotation speed command value (2000 rpm). As a result, the inverter control unit 16 gradually decreases the rotational speed after t44 in order to set the rotational speed of the compressor 15 maintained at 2000 rpm to 200 rpm.

  On the other hand, the AC voltage continues to decrease after t44 and decreases to about 100 volts at t45. Correspondingly, the DC voltage gradually decreases after t44. Further, the inverter control unit 16 was able to maintain the rotation of the compressor 15 at 2000 rpm and the load current at 10 amperes at t44. However, since the DC voltage gradually decreased, the load current gradually increased correspondingly. ing.

  Since the DC voltage has dropped to 220 volts at t45, the DC voltage drop detection unit 22 outputs the DC voltage drop signal from low level to high level (DC voltage drop occurrence). Therefore, since the OR circuit 27 outputs the relay open signal from the low level to the high level (relay 6 is opened), the AND circuit 30 outputs the relay control signal at the low level, and the relay 6 is opened at t45. Become.

  For this reason, the rotation speed of the compressor 15 that has decreased to 1900 rpm at t45 continues to rotate due to inertia, and then stops at t46. On the other hand, since the control unit 17 monitors the relay control signal, the instantaneous voltage drop processing unit 20 opens the relay 6 when the relay command signal instructed to close is different from the input relay control signal. At t45, the relay command signal and the fan motor command signal are set to the low level, and the rotation speed command value is set to 0 rpm and output. Since the relay 6 is opened at t45 and the load is rapidly reduced, the voltage across the smoothing capacitor 9 once rises and then gradually decreases to 0 volt at t49.

  Then, after t45, when the AC voltage gradually increases and exceeds the voltage sag threshold at t47, the voltage sag detector 21 outputs the voltage sag detection signal from high level to low level (instantaneous voltage drop has not occurred). To do. For this reason, the rotational speed command value switching unit 26 switches the rotational speed command value from the minimum rotational numerical value (200 rpm) to the stored rotational speed command value (0 rpm) and outputs it. Further, since the detection operation of the DC voltage drop detection unit 22 to which the low level instantaneous drop detection signal is input at t47 is prohibited, the DC voltage drop signal is output from the high level to the low level.

  As described above, even if the load of the compressor 15 described in FIG. 3 and the load of the compressor 15 described in FIG. 5 are the same, the air-conditioning operation cannot be continued if the voltage drop of the instantaneous voltage drop is large. However, the operation can be stopped as low voltage protection before the components of the inverter 14 are destroyed. That is, the air conditioning operation can be continued as long as possible without destroying the parts.

  As described with reference to FIGS. 3 to 5, the load current is reduced by reducing the rotation speed of the compressor 15 with the occurrence of the instantaneous voltage drop, and as a result, the consumption of the electric charge of the smoothing capacitor 9 is suppressed. Thus, the outdoor unit 1 is controlled. For this reason, the operation of the compressor 15 can be continued as much as possible when an instantaneous voltage drop occurs without increasing the capacity of the smoothing capacitor 9 provided in the DC power supply 18 supplied to the compressor 15.

In the present embodiment, the load device that operates using a DC voltage is described as the fan motor 11. However, the present invention is not limited to this, and the load device operates using the voltage of the smoothing capacitor 9, and temporarily. Any device may be used as long as it does not hinder the operation of the outdoor unit 1 even when the operation is stopped.
In this embodiment, the instantaneous voltage drop processing unit 20 is described as hardware. However, the present invention is not limited to this, and may be realized by software.

DESCRIPTION OF SYMBOLS 1 Outdoor unit 2 AC power supply 3 L terminal 4 N terminal 5 AC voltage detection part 6 Relay 7 Reactor 8 Rectifier 9 Smoothing capacitor 10 Fan motor drive part 11 Fan motor 12 DC voltage detection part 13 Load current detection part 14 Inverter 15 Compressor 16 Inverter control section 17 Control section 18 DC power supply 20 Instantaneous voltage drop processing section (instantaneous voltage drop processing means)
DESCRIPTION OF SYMBOLS 21 Instantaneous voltage drop detection part 22 DC voltage drop detection part 23 Overcurrent detection part 24 Minimum rotation numerical value memory | storage part 25 Rotation speed command value memory | storage part 26 Rotation speed command value switching part 27 OR circuit 28 Not circuit 29 Not circuit 30 And circuit 31 AND circuit

Claims (2)

A DC power supply including a rectifier and a smoothing capacitor to which AC power is input;
An inverter to which a DC voltage output from the rectifier is input;
A compressor driven by the inverter;
An inverter control unit for controlling the inverter;
An AC voltage detector that detects an input voltage of the AC power supply and outputs an AC voltage value;
A control unit for outputting a rotation speed command value for instructing the rotation speed of the compressor to the inverter control unit;
And an instantaneous voltage reduction processing means for outputting the rotational speed command value for reducing the rotational speed of the compressor when the AC voltage is reduced to a threshold value that is a predetermined voltage value or less. Air conditioner. The air conditioner further includes a load device that operates using the DC voltage,
2. The air conditioner according to claim 1, wherein the instantaneous voltage drop processing unit stops the operation of the load device when the AC voltage drops below the instantaneous drop threshold.

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