JPH04161753A - Air conditioner - Google Patents

Abstract

PURPOSE:To avoid unnecessary reduction in capability in an output current protection and improve a comfortable state by a method wherein an output current of an inverter is detected and then a setting of a current value is varied in compliance with a temperature of surrounding air and an amount of air in a fan. CONSTITUTION:An air conditioner comprises of a current value determining means for determining a current value for applying a protection against an inverter circuit 15 is response to an output of a fan air volume control means 22, a comparator means 24 for comparing the determined current value with a current value detected by a current value detecting means 21, a frequency command means 17 for judging states of an indoor device 11 and an outdoor device 12 and commanding a frequency for operating a compressor 1, and a frequency determining means 25 for determining a frequency operated on the basis of a result determined by the comparator means 24 at a command frequency determined by the frequency command means 17. With such an arrangement, an output current of an inverter circuit 15 is detected, and a setting of the current value for performing a protection is changed in compliance with a temperature of surrounding air and an amount of air of a fan and when there is a certain surplus state in the inverter circuit 15, its capability is applied as much as possible and then it is possible to avoid unnecessary reduction in an output current protection of the air conditioner and to improve a comfortable state in a room.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an air conditioner equipped with an inverter device for controlling the rotation speed of a compressor.

BACKGROUND OF THE INVENTION In recent years, many air conditioners have been used that control capacity by increasing or decreasing the rotational speed of a compressor using an inverter circuit that varies the frequency of a power source.

As a conventional technique, for example, Japanese Patent Application Laid-Open No. 62-25896
As disclosed in Publication No. 5, a compressor, an inverter circuit that adjusts the capacity of the compressor in multiple stages by changing the operating frequency of the compressor, and a current value on the input side or output side of the inverter circuit are disclosed. and a current value determining means for detecting, and when the current value horizontally determined by the current value determining means exceeds the rated current value of the inverter circuit, the operating frequency of the compressor is changed to a lower setting, and the compressor is A device is known in which the rotational speed is lowered to effectively protect the inverter circuit from overcurrent.

Problems to be Solved by the Invention However, in the conventional configuration, the current detection setting value was always set to a certain constant value, assuming the worst condition, regardless of surrounding conditions. In other words, when the output current reaches the current detection set value regardless of surrounding conditions, the operating frequency of the compressor is changed to a lower setting to protect the inverter circuit. However, with this kind of control, for example, when the outside temperature is low, or even when the outside temperature is high, when the outdoor unit fan's air volume is in the "strong mode" (when the outdoor unit fan's air volume is in the "strong mode", air flows into the inverter circuit). (The amount of air generated will also increase, and the temperature rise in the inverter circuit will be alleviated.) However, this means that it is still being maintained. Therefore, even though the inverter circuit can continue to operate, the problem is that the rotational speed of the compressor is reduced, the capacity of the air conditioner is reduced, and comfort is impaired as a result. .

In view of the above problems, the present invention detects the input or output current, and changes the current value setting according to the outside temperature and fan air volume based on the relationship of the inverter output current with the outside temperature and outdoor unit fan air volume. The purpose is to avoid unnecessary capacity reduction in output current protection of the device and improve the comfort of the air conditioner.

Means for Solving the Problems In order to solve the above problems, the air conditioner of the present invention includes a current value determining means for detecting the input or current of an inverter circuit, and an outside temperature sensor placed inside the outdoor unit. and outside temperature detection means for detecting outside temperature from the outside temperature sensor;
fan air volume control means for controlling fan air volume by controlling the rotation speed of an outdoor unit fan; and a current for determining a current value for applying protection to the inverter circuit according to outputs of the fan air volume control means and the outside temperature detection means. a value determining means;
Comparing means for comparing the current value determined by the current value determining means and the current value detected by the current value determining means, and determining the operating state of the indoor unit and the outdoor unit and commanding the operating frequency of the compressor. and a frequency determining means that determines the operating frequency based on the command frequency determined by the frequency command means and the result determined by the comparison means.

Operation The present invention has the above-described configuration, detects the input or output type m, changes the current value setting according to the outside temperature and fan air volume based on the relationship between the outside temperature and fan air volume, and inverter output current. By making the most of the circuit's capacity when there is room, it is possible to avoid unnecessary capacity reductions in the output current protection of the air conditioner and improve comfort.

EXAMPLE Hereinafter, an air conditioner according to an example of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of an air conditioner according to an embodiment of the present invention. In Fig. 1, 1 is a compressor, 2 is a four-way valve,
8 is an indoor heat exchanger, 4 is a pressure reducing device, and 5 is an outdoor heat exchanger, which are connected in a ring to form a refrigeration circuit. 6 is an indoor fan, and 7 is an outdoor fan. 8 is a room temperature sensor that detects the indoor temperature. Reference numeral 9 denotes a room temperature setting device, which sets the room temperature. Reference numeral 10 denotes an indoor control circuit, into which output signals from a room temperature sensor 8 and a room temperature setting device 9 are input. 11 is an indoor unit in the air conditioner, and 12 is an outdoor unit. 13 is a three-phase AC power supply, 14 is a rectifier circuit,
The input of the three-phase AC power supply 13 is directly converted. 15 is an inverter circuit that converts the output of the rectifier circuit 14 into variable frequency three-phase alternating current to drive the compressor 1. 16 is an outdoor control circuit which receives commands from the indoor control circuit 10 and controls the outdoor unit 1.
Determine the second action. Reference numeral 17 denotes a frequency command means, which determines the states of the indoor unit 11 and the outdoor unit 12 and commands the frequency at which the compressor 1 is operated. Reference numeral 18 denotes an outside temperature detection means, which detects the outside temperature using an outside temperature sensor 19 placed inside the outdoor unit 12. Reference numeral 20 denotes a current sensor that measures the output current of the inverter. Reference numeral 21 denotes a current value determining means, which detects the value of the flowing current based on the output of the current sensor 20. Reference numeral 22 denotes a fan air volume control means for controlling the rotation speed of the outdoor unit fan 7. Further, the fan air generated by the outdoor unit fan 7 also flows into the inverter circuit 15. 28 is a current value determining means, and an outside temperature detector m
A current value for applying protection to the inverter circuit 15 is determined in accordance with the output of is.

Further, 24 is a comparison means, which compares the current value determined by the current value determining means 23 and the current value detected by the current value determining means 21. 25 is a frequency determining means 1
, the operating frequency is determined based on the command frequency determined by the frequency command means 17 and the result determined by the comparison means 24. 24 is a waveform generating means, and the frequency determining means 2
A waveform corresponding to the frequency determined in step 5 is output, and the inverter circuit 15 is operated.

The operation of the air conditioner configured as described above will be described below with reference to FIGS. 1, 2, 3, and 4. First, the operation in the normal state will be explained using FIG. 1. In the indoor unit 11, first I! E Set the desired temperature in the temperature setting setter 9. The indoor control circuit 10 detects this set temperature and the current room temperature detected by the room temperature sensor 8, and controls the air volume of the indoor fan 6 (for example, "strong", "medium", "weak", "stop", etc.). )
At the same time, the operating state of the indoor unit 11 (for example, the difference between the room temperature and the set temperature) is sent to the outdoor control circuit 16. Outdoor control circuit 1
6 takes into account the operating status of the indoor unit 11 and the operating status of the outdoor unit 12, and calculates the load on the outdoor unit (four-way valve 2, outdoor fan 7, etc.)
In the normal state, the frequency command means 17 determines the operating frequency of the compressor 1 according to the state of the indoor unit 11 and the state of the outdoor unit 12, and sends the frequency command to the frequency determining means 25. Since this is not a necessary state, the frequency sent from the frequency command means 17 is directly sent to the waveform generation means 26 as the determined frequency. The waveform generating means 26 sends out a waveform for operating the inverter circuit 15 according to the determined frequency. In the inverter circuit 15, a power device (for example, a transistor, not shown) is turned ON10 according to the output of the waveform generating means 26.
FF to operate the compressor 1 at the determined frequency. Next, the operation during protection will be explained. FIG. 2 is a flowchart of a process for determining protection. In FIG. 2, first, the command frequency fs of the frequency command means 17 is input (ST
EPI), then the outside temperature is detected by the outside temperature detection means 18 from the outside temperature sensor 19 placed inside the outdoor unit 12, and the detected outside temperature is then determined by the current value determination means 23. 5TEP2 ), 5TEP depending on the judgment result.
3~5TEP5" Set the current value that becomes the reference for t'. Here, when the outside temperature < TI, set the current value ITI. 5T
EPa), when T1≦outside temperature <72, set the current value IT2 5TEP4), when T2≦outside temperature, set the current value IT3
(STEP 5), but here [T1>IT2
>IT3, T2>TI (TI.

T2 is a comparison value of outside temperature).

Next, the current fan air volume (for example, "strong", "weak", "stop", etc.) is output from the fan air volume control means 22 that controls the air volume of the fan of the outdoor unit 12 (5TEP6).
Next, the output fan air volume is determined by the current value determining means 23, and a reference current value is set in 5TEP7 to 5TEP9 according to the determination result. Here the fan stops <Fl
When F1≦Fan Weak<F2, set the current value IP2.STE
F8), when F2≦fan strong, set the current value IF3t- (STEP9), but here IFI<IF2<IF5
, F2>Fl (Fl and F2 are comparison values of fan air volume).

Next, the current value IT set in 5TEP3 to 5TEP5,
At the current value IP set in 5TEP7 to 5TEP9, the current value determining means 28 compares the current value IT and the current value rFf: and sets the maximum value as Is (STEPI
O), Next, detect the current value Id actually floating in the inverter circuit 15 (in the case of this embodiment, the output current of the inverter circuit 15) (5TEPI 1 )11 Next, 5TE
The current value Is obtained by P10 and the current value detected by 5TEPII! 5TEP12), if Id≦Ig, normal operation is performed (STEPI3), and the inverter circuit 15 is operated using the command frequency fs as the determined frequency; on the other hand, if 1d > [s, protective operation is performed. (STEP 14), and the device is forced to operate at a frequency one step lower than the current operating frequency (for example, a frequency decreased by 10 Hz) for a certain period of time (for example, 10 minutes), without any difference from the command frequency. During this time, if the current value exceeds the set value, the frequency is further lowered by one step. After a certain period of time, normal operation will resume.

Next, the current values determined as the outside temperature and fan air volume by the current value determining means 28 will be explained.

FIG. 3 is a characteristic diagram showing the relationship between the outside temperature, the fan air volume, and the current value determined by the current value determining means 23 in this embodiment. The horizontal axis shows the outside temperature and the fan air volume, and the vertical axis shows the current value. When the outside temperature is < TI, set the current value ``ITI'' and set T1.
When T2≦outside temperature <72, the current value IT2 is set, and when T2≦outside temperature, the current value IT3 is set. The fan stopped again
When it is Fl, set the current value IFI, F1≦Fan weak<F
2, set the current value IP2, and when F2≦fan strong, set the current value IF3. This current value IT, current value IP
Take the maximum value according to each condition of 12.13 tl
Let it be s. In the conventional example, the determined current value is always set to a current value of 11 so that protection can be achieved under the worst conditions.

Next, an example of the operation of the air conditioner employing this embodiment will be explained using FIG. 4. FIG. 4 is a timing chart showing an example of the operation of the air conditioner employing this embodiment, and FIG. 4(a) shows the operating time on the horizontal axis, the change in output current value on the vertical axis, and In Figure (b), the horizontal axis shows operating time and the vertical axis shows changes in operating frequency. Here, it is assumed that the outside temperature is T1≦outside temperature<72, and F2≦fan strength. Further, the operation in this embodiment is shown by a solid line, and the conventional operation is shown by a chain line.

First, the conventional operation will be explained.With a constant zero frequency, as the load gradually becomes heavier, the output current also increases accordingly. Then, at time t1, the protection setting current ■1 is reached, a protection operation is performed, and the frequency is lowered by one step. After 0 time Δt, the output current has not reached the protection setting current ■1, so the original operation is resumed. . This operation is repeated, and at time t2, the protection setting current 11 is changed, a protection operation is performed, and the frequency is lowered by one step.

Next, the operation in this embodiment will be explained at time 0 t1.
The output current reaches 11, but the outside temperature is T1.
≦Outside temperature<72. Since F2≦fan strong, the protection setting current is l from Is=MAX(IT2.IF3) in Figure 3.
5=IF3=13, setting current at tl! In 1,
No protective operation is performed and normal operation continues. On the way, the frequency increases and the load becomes heavier, and when the protection setting current I3 is reached at time t2, a protection operation is performed,
After 0 time Δt when the frequency is lowered by one step, the output current has not reached the protection setting type 81 of 8, so the original operation is returned to 0. In this embodiment, this operation is repeated.

As described above, according to this embodiment, the current detection device M21 detects the output current of the inverter circuit 15, the outside temperature sensor 19 placed inside the outdoor unit, and the outside temperature sensor 19.
an outside air temperature detection means 18 that detects the outside air temperature; a fan air volume control means 22 that controls the fan air volume by controlling the rotation speed of the outdoor unit fan; Current value determining means 23 for determining the current value to apply protection, and current value determining means 2
Comparing means 24 compares the current value determined by 3 with the current value detected by the current value determining means 21, determines the states of the indoor unit 11 and the outdoor unit 12, and commands the frequency at which the compressor 1 is operated. The inverter circuit 1
5 is detected, and based on the relationship between the outside temperature and fan air volume and the inverter output current, the setting of the current value for protection is changed according to the outside temperature and fan air volume, and when there is sufficient margin in the inverter circuit 15. By making the most of its ability, it is possible to avoid unnecessary capacity reductions in the output current protection of air conditioners and improve comfort. When you need more capacity, such as when you need 7 reed airflow, you can draw out a greater capacity than before, so you can use it for heating, cooling (dehumidification), etc.
This results in a significant improvement in comfort.

In the embodiment, the output current of the inverter circuit is detected, but the same effect can be obtained by detecting the input current.

Effects of the Invention As described above, the present invention provides a current value determining means for detecting the input or output current of an inverter circuit, an outside temperature sensor placed inside an outdoor unit, and an outside temperature sensor that detects the outside temperature from the outside temperature sensor. an outside temperature detection means, a fan air volume control means for controlling the fan air volume by controlling the rotation speed of the outdoor unit fan, and a current value for determining a current value for applying protection to the inverter circuit according to the pressure of the fan air volume control means. a means of determining;
Comparing means for comparing the current value determined by the current value determining means and the current value detected by the current value determining means, and determining the states of the indoor unit and the outdoor unit, and commanding the operating frequency of the compressor. By providing a frequency command means for determining the operating frequency based on the command frequency determined by the frequency command means and the result determined by the comparison means, the outside temperature, the fan air volume, and the inverter can be adjusted. In relation to the output current, the current value setting is changed according to the outside temperature and fan air volume, thereby avoiding unnecessary capacity reduction in the output current protection of the air conditioner and improving the comfort of the air conditioner. The practical effects are great.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an air conditioner according to an embodiment of the present invention, FIG. 2 is a flowchart of a process for determining protection, and FIG. 3 is a diagram showing the outside temperature, fan air volume, and current value determined by the Characteristic diagram showing the relationship between current value and current value, 4th
The figure is a timing chart showing an example of the operation of the air conditioner employing the embodiment. DESCRIPTION OF SYMBOLS 1...Compressor, 15...Inverter circuit, 21...Current value determining means, 18...
・Outside temperature detection means, 19...Outside temperature sensor, 2
2...--Fan air volume control means, 23...-...
Current value determining means, 24... Comparison means, 16...
. . . Frequency command means, 25 . . . Frequency determination means. Agent's name Patent attorney Akira Okaji Two idiots 1-11 pressure umbrella? Aircraft a 111 Figure 2 [] 3rd Embarrassment Quantity 1 -

Claims (1)

[Claims] A compressor, an inverter circuit for controlling the rotation speed of the compressor, a current detection means for detecting input or output current of the inverter circuit, an outside temperature sensor placed inside the outdoor unit, and the outside temperature sensor. an outside air temperature detection means for detecting an outside air temperature from the outdoor unit; a fan air volume control means for controlling fan air volume by controlling the rotation speed of an outdoor unit fan; A current value determining means for determining a current value for applying protection to a circuit; a comparing means for comparing a current value determined by the current value determining means with a current value detected by the current detecting means; and an indoor unit. a frequency command means for determining the operating state of the outdoor unit and commanding the operating frequency of the compressor; and determining an operating frequency based on the command frequency determined by the frequency command means and the result determined by the comparison means. An air conditioner characterized by comprising: frequency determining means.