JP2008128551A - Control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device of an air conditioner, preventing unnecessary breaker operation. <P>SOLUTION: This control device 4 is a control device of the air conditioner 1 loaded with a variable displacement inverter compressor 11, and provided with a micro-computer 5. The micro-computer 4 controls the air conditioner 1 based upon the refrigerant state of a refrigerant circuit 10 including the inverter compressor 11. The micro-computer 5 computes an estimated value of a total consumption current in the air conditioner 1 in the case of raising the operational frequency in raising the operational frequency of the inverter compressor 11, and the estimated value and a preset total consumption current upper limit value are compared to determine permission or non-permission to raise the operational frequency. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an air conditioner control device, and more particularly to an air conditioner control device including an inverter compressor having a variable capacity.

Conventionally, air conditioners equipped with inverter compressors are limited in capacity so that the current consumption does not exceed the specified value, or the sum of the current consumption of the air conditioner and the current consumption of other equipment is There is one that limits the capacity so as not to exceed the breaker capacity of the switchboard (for example, see Patent Document 1).
Japanese Patent Laid-Open No. 63-041754

  Even if the current consumption is close to the specified value or the breaker capacity, the air conditioner as described above tries to operate by setting a stepwise capacity limit, so the breaker operates frequently and the operation is unstable. Is likely to be.

  The subject of this invention is providing the control apparatus of the air conditioner which can prevent an unnecessary breaker operation | movement.

  A control device according to a first aspect of the present invention is a control device for an air conditioner equipped with an inverter compressor having a variable capacity, and includes a microcomputer. The microcomputer controls the air conditioner based on the refrigerant state. In addition, when increasing the operating frequency of the inverter compressor, the microcomputer calculates the predicted value of the total current consumption in the air conditioner when the operating frequency is increased, and the predicted value and the preset total current consumption Is compared with the upper limit value, and permission or non-approval of the increase of the operating frequency is determined.

  In this control device, when the predicted value of the total current consumption exceeds the upper limit value, an increase in the operating frequency is prohibited. For this reason, an increase in current consumption is suppressed, and an unnecessary stop of the air conditioner is prevented.

  The control device according to the second invention is the control device according to the first invention, and further includes one or a plurality of constant capacity compressors. When starting the constant capacity compressor, the microcomputer calculates the predicted value of the total current consumption in the air conditioner when the constant capacity compressor is started, and permits the start of the constant capacity compressor based on the predicted value Or decide not to permit.

  In this control device, when the predicted value of the total current consumption exceeds the upper limit value, the start of the constant capacity compressor is prohibited. For this reason, an unnecessary breaker operation is suppressed and the operation of the air conditioner is stabilized.

  A control device according to a third aspect of the invention is a control device for an air conditioner equipped with a plurality of constant capacity compressors, and includes a microcomputer. The microcomputer controls the air conditioner based on the refrigerant state. The microcomputer also predicts the total current consumption in the air conditioner when another constant capacity compressor is activated when another constant capacity compressor is activated when one constant capacity compressor is in operation. A value is calculated, and the predicted value is compared with a preset upper limit value of the total current consumption to determine whether or not to start another constant capacity compressor.

  In this control apparatus, when the predicted value of the total current consumption exceeds the upper limit value, activation of other constant capacity compressors is prohibited. For this reason, an unnecessary breaker operation is suppressed and the operation of the air conditioner is stabilized.

  A control device according to a fourth aspect of the present invention is the control device according to the first aspect of the present invention, wherein after the microcomputer obtains the characteristic value change amount of the refrigerant state when the operating frequency is increased, the inverter compression is performed from the characteristic value change amount. The inverter current of the machine is calculated, and the predicted value of the total current consumption is further calculated from the calculated value of the inverter current.

  In this control apparatus, since the microcomputer calculates the inverter current from the characteristic value of the refrigerant state, the accuracy of the predicted value of the total current consumption is increased. For this reason, permission or non-permission of an increase in operating frequency is correctly determined.

  The control device according to the fifth invention is the control device according to the second invention or the third invention, and after the microcomputer 5 obtains the characteristic value change amount of the refrigerant state when starting the constant capacity compressor, The current of the constant capacity compressor is calculated from the characteristic value change amount, and the predicted value of the total current consumption is further calculated from the calculated current value.

  In this control apparatus, since the microcomputer calculates the current of the constant capacity compressor from the characteristic value of the refrigerant state, the accuracy of the predicted value of the total current consumption is increased. For this reason, whether or not to start the constant capacity compressor is correctly determined.

  A control device according to a sixth invention is the control device according to the fourth or fifth invention, wherein the microcomputer has a relational expression for obtaining the characteristic value change amount. In this control device, the accuracy of the predicted value of the total current consumption is high.

  A control device according to a seventh aspect of the present invention is the control device according to the fourth or fifth aspect of the present invention, further comprising a memory that stores the characteristic value change amount in advance. In this control device, the accuracy of the predicted value of the total current consumption is high.

  A control device according to an eighth invention is the control device according to the fourth or fifth invention, wherein the characteristic value of the refrigerant state includes the high-pressure side pressure and the low-pressure side pressure of the refrigerant circuit.

  In this control device, the high-pressure side pressure and the low-pressure side pressure can be directly measured by a pressure sensor and indirectly measured by a temperature sensor, and an existing sensor is used for an air conditioner. For this reason, cost is reduced.

  A control device according to a ninth invention is the control device according to any one of the first to third inventions, wherein the upper limit value of the total current consumption is an operating value of a breaker provided in the air conditioner. .

  In this control apparatus, since the interruption | blocking by a breaker is prevented, the unnecessary stop of an air conditioner is prevented and an operation | movement is stabilized.

  In the control device according to the first aspect of the invention, when the predicted value of the total current consumption exceeds the upper limit value, an increase in the operating frequency is prohibited. For this reason, an increase in current consumption is suppressed, and an unnecessary stop of the air conditioner is prevented.

  In the control device according to the second aspect of the present invention, the start of the constant capacity compressor is prohibited when the predicted value of the total current consumption exceeds the upper limit value. For this reason, an unnecessary breaker operation is suppressed and the operation of the air conditioner is stabilized.

  In the control device according to the third aspect of the present invention, when the predicted value of the total current consumption exceeds the upper limit value, activation of other constant capacity compressors is prohibited. For this reason, an unnecessary breaker operation is suppressed and the operation of the air conditioner is stabilized.

  In the control device according to the fourth aspect of the invention, the microcomputer calculates the inverter current from the characteristic value of the refrigerant state, so that the accuracy of the predicted value of the total current consumption is increased. For this reason, permission or non-permission of increase in the operating frequency is correctly determined.

  In the control device according to the fifth aspect of the invention, the microcomputer calculates the current of the constant capacity compressor from the characteristic value of the refrigerant state, so that the accuracy of the predicted value of the total current consumption is increased. For this reason, whether or not to start the constant capacity compressor is correctly determined.

  In the control devices according to the sixth and seventh inventions, the accuracy of the predicted value of the total current consumption is high.

  In the control device according to the eighth invention, the high-pressure side pressure and the low-pressure side pressure can be directly measured by the pressure sensor and indirectly measured by the temperature sensor, and an existing sensor is used for the air conditioner. For this reason, cost is reduced.

  In the control device according to the ninth aspect of the invention, since the interruption by the breaker is prevented, unnecessary stop of the air conditioner is prevented and the operation is stabilized.

[First Embodiment]
<Configuration of air conditioner>
FIG. 1 is a configuration diagram of an air conditioner. The air conditioner 1 is a multi-type air conditioner for buildings, and is an inverter compressor so that a plurality of indoor units 3 are connected in parallel to one or a plurality of outdoor units 2 so that refrigerant can circulate. 11, a constant capacity compressor 111, a four-way switching valve 12, an outdoor heat exchanger 13, an outdoor expansion valve 14, an indoor expansion valve 15, and an indoor heat exchanger 16 are connected to form the refrigerant circuit 10. Yes. The inverter compressor 11 is operated by the rotational speed control by the inverter and has a variable capacity. The constant capacity compressor 111 is operated by on / off control and has a constant capacity.

  An outdoor fan 44 is provided in the vicinity of the outdoor heat exchanger 13, and the refrigerant exchanges heat with the air flow generated by the outdoor fan 44. An indoor fan 45 is provided in the vicinity of the indoor heat exchanger 16, and the refrigerant exchanges heat with the air flow generated by the indoor fan 45.

  The high pressure sensor 46 is provided on the discharge pipe side of the compressors 11 and 111 and detects the high pressure side pressure of the refrigerant circuit 10. The low pressure sensor 47 is provided on the suction pipe side of the compressors 11 and 111 and detects the low pressure side pressure of the refrigerant circuit 10.

  The control device 4 controls the compressors 11, 111, the outdoor expansion valve 14 and the indoor expansion valve 15 in order to achieve high efficiency operation of the air conditioner 1. Further, the control device 4 includes a microcomputer 5 and a memory 6 in order to calculate a control value from values measured by various sensors.

<Operation of air conditioner>
(Cooling operation)
During the cooling operation, the four-way switching valve 12 is connected as shown by the solid line in FIG. 1, the compressors 11 and 111 and the outdoor heat exchanger 13 communicate with each other, and the outdoor heat exchanger 13 and the indoor heat exchanger 16. Respectively function as a radiator and an evaporator. That is, the high-temperature and high-pressure refrigerant discharged from the compressors 11 and 111 is introduced into the outdoor heat exchanger 13 to dissipate heat and the temperature decreases. The refrigerant that has become medium temperature and high pressure through the outdoor heat exchanger 13 is depressurized by the indoor expansion valve 15, becomes a low-temperature and low-pressure two-phase refrigerant, and is introduced into the indoor heat exchanger 16. Here, after heat exchange with room air is performed, the air is sucked into the compressors 11 and 111 again.

(Heating operation)
On the other hand, during the heating operation, the four-way switching valve 12 is connected as shown by the dotted line in FIG. 1, the compressors 11 and 111 and the indoor heat exchanger 16 communicate with each other, and the indoor heat exchanger 16 and the outdoor heat exchange are connected. The units 13 function as a radiator and an evaporator, respectively. That is, the high-temperature and high-pressure refrigerant discharged from the compressors 11 and 111 is introduced into the indoor heat exchanger 16 and exchanges heat with the indoor air, so that the temperature decreases and the medium and high-pressure states are obtained. Thereafter, the refrigerant passes through the pipe, is decompressed by the outdoor expansion valve 14, and is introduced into the outdoor heat exchanger 13. Here, heat exchange with outdoor air is performed, and the air is sucked into the compressors 11 and 111 again.

<Control device>
FIG. 2 is an electric circuit diagram of the control device according to the first embodiment of the present invention. In control device 4, the R phase, S phase, and T phase of AC power supply 7 are connected to converter 8 in order to convert the output of AC power supply 7 to DC. The inverter 9 converts the direct current output from the converter 8 into alternating current having an arbitrary frequency and supplies the alternating current to the motor of the inverter compressor 11. The inverter 9 is driven by a drive circuit 42, and the drive circuit 42 is controlled by the microcomputer 5.

  Further, the microcomputer 5 monitors the current flowing through the inverter 9 via the inverter current detection circuit 41 and the resistor 91. The resistor 91 is connected in series with the inverter 9.

  In the present embodiment, a breaker 71 is installed between the AC power supply 7 and the converter 8, and when the total current consumption of the outdoor unit 2 exceeds the operating value of the breaker 71, the AC power supply 7 transfers to the control device 4. The power supply of is interrupted. A current sensor (not shown) is built in the breaker 71, and a detection value of the current sensor is input to the microcomputer 5.

<Predictive control of total current consumption>
The breaker 71 operates in response to an overcurrent due to a short circuit, but may operate when the operating frequency of the inverter compressor 11 is increased. As the air conditioner 1, it is preferable to continue the operation without stopping unless a fatal failure such as a short circuit occurs.

  Therefore, in this embodiment, before increasing the operating frequency of the inverter compressor 11, the total current consumption after the operating frequency is increased is predicted to determine whether the operating frequency can be increased. This will be described below with reference to the drawings.

  FIG. 3 is a flowchart of predictive control of total current consumption. In step S1, the microcomputer 5 detects the current total consumption current Q via the current sensor.

  In step S2, the microcomputer 5 determines whether or not the total current consumption Q is less than an allowable value. This allowable value is set to a value lower than the breaker operating value. When it determines with Yes at step S2, it progresses to step S3. In addition, when it determines with No by step S2, it progresses to step S7, the operating frequency of the inverter compressor 11 is reduced, and the total consumption current Q is reduced.

  In step S <b> 3, the microcomputer 5 determines whether it is necessary to increase the operating frequency of the inverter compressor 11. When it determines with Yes at step S3, it progresses to step S4. If it is determined No in step S3, the process returns to step S1.

  In step S4, the microcomputer 5 calculates the predicted value Qc of the total current consumption after the operating frequency of the inverter compressor 11 is increased. In order to calculate the predicted value Qc of the total current consumption, the memory 6 stores in advance the amount of change in the characteristic value of the refrigerant state due to the increase in the operating frequency. Specifically, the amount of change in high-pressure side pressure, the amount of change in low-pressure side pressure, and the amount of change in superheat are stored, and the microcomputer 5 calculates the amount of current change from the amount of change in the characteristic value of the refrigerant state, The predicted value Qc is calculated by adding to the total consumption current Q detected in step S1.

  In step S5, the microcomputer 5 determines whether or not the predicted value Qc is less than the breaker operating value. When it determines with Yes at step S5, it progresses to step S6.

  In step S6, the microcomputer 5 permits an increase in the operating frequency of the inverter compressor 11, and returns to step S1.

  In addition, when it determines with No by step S5, it progresses to step S8 and prohibits the raise of the operating frequency of the inverter compressor 11.

<Modification>
In step S1, the total current consumption of the outdoor unit 2 is measured with a current sensor. However, this type of current sensor is an expensive part using a Hall IC, which causes an increase in cost. Therefore, cost reduction can be realized by calculating the total current consumption.

  FIG. 4 is a flowchart of the total current consumption predictive control in the modification of the first embodiment. In step S1a, the current Qf of the outdoor fan 44 is detected. In step S1b, the current Qi of the inverter compressor 11 is detected. In step S1c, the total current consumption Q is calculated. The total consumption current Q is the sum of the fan current Qf, the compressor current Qi, and the current α flowing through other control devices. Since the control after step S2 is the same as in the first embodiment, a description thereof will be omitted.

<Features of First Embodiment>
(1)
In this control device 4, when the microcomputer 5 increases the operating frequency of the inverter compressor 11, it calculates a predicted value of the total current consumption in the air conditioner 1 when the operating frequency is increased.

  In this control device, when the predicted value of the total current consumption exceeds the breaker operating value, the increase of the operating frequency is prohibited. For this reason, an unnecessary breaker operation is prevented and the operation of the air conditioner 1 is stabilized.

(2)
In this control device 4, since the microcomputer 5 calculates the inverter current from the characteristic value of the refrigerant state, the accuracy of the predicted value of the total current consumption is increased, and permission or non-permission of increase in the operating frequency is correctly determined. Note that the high pressure side pressure and the low pressure side pressure, which are characteristic values of the refrigerant state, are directly measured by the existing high pressure sensor 46 and low pressure sensor 47 in the air conditioner 1, so that no extra equipment is required and the cost is reduced. .

[Second Embodiment]
In the second embodiment, before starting the constant capacity compressor 111, the total current consumption after startup is predicted to determine whether or not startup is possible. This will be described below with reference to the drawings.

<Predictive control of total current consumption>
FIG. 5 is a flowchart of the total current consumption predictive control. In step S11, the microcomputer 5 detects the current total current consumption Q via the current sensor.

  In step S12, the microcomputer 5 determines whether or not the total current consumption Q is less than the allowable value. The allowable value is set to a value lower than the breaker operating value. When it determines with Yes at step S12, it progresses to step S13. In addition, when it determines with No by step S12, it progresses to step S17, the operating frequency of the inverter compressor 11 is reduced, and the total consumption current Q is reduced.

  In step S <b> 13, the microcomputer 5 determines whether the constant capacity compressor 111 needs to be activated. When it determines with Yes at step S13, it progresses to step S14. In addition, when it determines with No by step S13, it returns to step S11.

  In step S14, the microcomputer 5 calculates a predicted value Qc of the total current consumption after the constant capacity compressor 111 is started. In order to calculate the predicted value Qc of the total current consumption, the memory 6 stores in advance the characteristic value change amount of the refrigerant state due to the start of the constant capacity compressor 111. Specifically, the amount of change in high-pressure side pressure, the amount of change in low-pressure side pressure, and the amount of change in superheat are stored, and the microcomputer 5 calculates the amount of current change from the amount of change in the characteristic value of the refrigerant state, The predicted value Qc is calculated by adding to the total current consumption Q detected in step S11.

  In step S15, the microcomputer 5 determines whether or not the predicted value Qc is less than the breaker operating value. When it determines with Yes at step S15, it progresses to step S16.

  In step S16, the microcomputer 5 permits activation of the constant capacity compressor 111, and returns to step S1.

  If it is determined No in step S15, the process proceeds to step S18, and activation of the constant capacity compressor 111 is prohibited.

<Features of Second Embodiment>
In the control device 4, the microcomputer 5 calculates a predicted value of the total current consumption in the air conditioner 1 when starting the constant capacity compressor 111. In this control device, when the predicted value of the total current consumption exceeds the breaker operating value, the start of the constant capacity compressor is prohibited. For this reason, an unnecessary breaker operation is prevented and the operation of the air conditioner is stabilized.

[Third Embodiment]
In the third embodiment, an air conditioner equipped with two constant capacity compressors is assumed, and a second constant capacity compressor (not shown) is activated during operation of the first constant capacity compressor 111. At this time, the total current consumption after startup is predicted to determine whether startup is possible. This will be described below with reference to the drawings.

<Predictive control of total current consumption>
FIG. 6 is a flowchart of predictive control of total current consumption. In step S21, the microcomputer 5 detects the current total current consumption Q via the current sensor.

  In step S22, the microcomputer 5 determines whether or not the total current consumption Q is less than the allowable value. The allowable value is set to a value lower than the breaker operating value. When it determines with Yes at step S22, it progresses to step S23. In addition, when it determines with No by step S22, it progresses to step S27, the 1st constant capacity compressor 111 is stopped, and the total consumption current Q is decreased.

  In step S23, the microcomputer 5 determines whether or not the second constant capacity compressor needs to be activated. When it determines with Yes at step S23, it progresses to step S24. In addition, when it determines with No by step S23, it returns to step S21.

  In step S24, the microcomputer 5 calculates a predicted value Qc of the total current consumption after the start of the second constant capacity compressor. In order to calculate the predicted value Qc of the total current consumption, the memory 6 stores in advance the amount of change in the characteristic value of the refrigerant state due to the start of the second constant capacity compressor. Specifically, the amount of change in high-pressure side pressure, the amount of change in low-pressure side pressure, and the amount of change in superheat are stored, and the microcomputer 5 calculates the amount of current change from the amount of change in the characteristic value of the refrigerant state, The predicted value Qc is calculated by adding to the total consumption current Q detected in step S21.

  In step S25, the microcomputer 5 determines whether or not the predicted value Qc is less than the breaker operating value. When it determines with Yes at step S25, it progresses to step S26.

  In step S26, the microcomputer 5 permits activation of the second constant capacity compressor, and returns to step S2.

  In addition, when it determines with No by step S25, it progresses to step S28 and prohibits starting of a 2nd constant capacity compressor.

<Features of Third Embodiment>
In the control device 4, the microcomputer 5 controls the air conditioner based on the refrigerant state of the refrigerant circuit including the two constant capacity compressors 111. When the microcomputer 5 starts the second constant capacity compressor when the first constant capacity compressor 111 is in operation, the microcomputer 5 calculates a predicted value of the total current consumption in the air conditioner 1 and calculates the predicted value. When the value exceeds the breaker operating value, starting of other constant capacity compressors is prohibited. For this reason, an unnecessary breaker operation is prevented and the operation of the air conditioner is stabilized.

[Other Embodiments]
As mentioned above, although this invention was demonstrated, a specific structure is not restricted to said each embodiment, It can change in the range which does not deviate from the summary of invention.

  For example, in each of the embodiments described above, the characteristic value change amount is stored in the memory 6 in advance, but it is also possible to obtain a relational expression in advance and obtain it by calculation.

  As described above, the control device according to the present invention predicts the total current consumption and suppresses the current consumption. For example, it is necessary to control the device before the breaker capacity is exceeded. It is useful in.

The block diagram of an air conditioner. The electric circuit diagram of the control apparatus which concerns on 1st Embodiment of this invention. The flowchart of the prediction control of the total consumption current in 1st Embodiment. The flowchart of the prediction control of the total consumption current in the modification of 1st Embodiment. The flowchart of the prediction control of the total consumption current in 2nd Embodiment. The flowchart of the prediction control of the total consumption current in 3rd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Air conditioner 4 Control apparatus 5 Microcomputer 6 Memory 10 Refrigerant circuit 11 Inverter compressor 111 Constant capacity compressor

Claims (9)

A control device for an air conditioner (1) equipped with an inverter compressor (11) having a variable capacity,
A microcomputer (5) for controlling the air conditioner (1) based on the refrigerant state;
When the microcomputer (5) increases the operating frequency of the inverter compressor (11), the microcomputer (5) calculates a predicted value of the total current consumption in the air conditioner (1) when the operating frequency is increased, Comparing the predicted value and the preset upper limit value of the total current consumption to determine whether to permit or disallow the increase in the operating frequency;
Control device (4). The air conditioner (1) further includes one or more constant capacity compressors (111),
When the microcomputer (5) starts the constant capacity compressor (111), the microcomputer (5) calculates a predicted value of the total current consumption in the air conditioner (1) when the constant capacity compressor (111) is started. And comparing the predicted value with a preset upper limit value of the total current consumption to determine whether to permit or disallow activation of the constant capacity compressor (111).
The control device (4) according to claim 1. A control device for an air conditioner (1) equipped with a plurality of constant capacity compressors (111),
A microcomputer (5) for controlling the air conditioner (1) based on the refrigerant state;
When the microcomputer (5) activates the other constant capacity compressor (111) while one of the constant capacity compressors (111) is operating, the other constant capacity compressor (111) The predicted value of the total current consumption in the air conditioner (1) when the air conditioner is activated is calculated, and the predicted value is compared with a preset upper limit value of the total current consumption to compare the other constant capacity compression To determine whether or not to start the machine (111),
Control device (4). The microcomputer (5) calculates an amount of change in the characteristic value of the refrigerant state when the operating frequency is increased, calculates an inverter current of the inverter compressor (11) from the amount of change in the characteristic value, and Further calculating the predicted value of the total current consumption from the calculated value of the inverter current,
The control device (4) according to claim 1. The microcomputer (5) obtains the characteristic value change amount of the refrigerant state when the constant capacity compressor (111) is started, and then determines the current of the constant capacity compressor (111) from the characteristic value change amount. And further calculating the predicted value of the total current consumption from the calculated value of the current,
The control device (4) according to claim 2 or claim 3. The microcomputer (5) has a relational expression for obtaining the characteristic value change amount.
Control device (4) according to claim 4 or 5. A memory (6) for storing the characteristic value change amount in advance;
Control device (4) according to claim 4 or 5. The characteristic value of the refrigerant state includes a high pressure side pressure and a low pressure side pressure of the refrigerant,
Control device (4) according to claim 4 or 5. The upper limit value of the total current consumption is the operating value of the breaker (71) provided in the air conditioner (1).
The control device (4) according to any one of claims 1 to 3.

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