JPH01203675A - Air conditioner - Google Patents

Abstract

PURPOSE:To surely perform oil uniform operation by reducing by a fixed value an output frequency of an inverter circuit while setting an output frequency of the other inverter circuit to the same value when an input current to the inverter circuit exceeds the preset value. CONSTITUTION:When an inverter circuit 51 is decided to be abnormal in its input current, the inverter circuit 51 reduces its output frequency by a fixed value, performing current release. Here a microcomputer 100 senses the current release to be performed in the inverter circuit 51 from that a content of an instruction to an inverter microcomputer 101 is different from the content of a return signal from the inverter microcomputer 101, immediately setting an output frequency of an inverter circuit 52 to the same value to the output frequency of the inverter circuit 51.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a multi-type air conditioner consisting of an outdoor unit and a plurality of indoor units.

(Prior Art) Generally, this type of air conditioner is shown in Fig. ψ.

A is an outdoor unit that has two variable capacity compressors and two inverter circuits that supply driving power to these compressors. A branch unit B is connected to this outdoor unit A, and indoor units CI, C2 and C3 of ff1i& are connected to the branch unit B.

That is, the indoor units C, , C2, and C3 use the frequency setting signals fl, f to set the required capacity according to their respective air conditioning loads.
2. It is sent to branch unit B as f3.

Branching unit B receives the received frequency setting signal fl,
f2. The required capacity of each indoor unit is determined from f3, and a frequency setting signal fo corresponding to the total sum is sent to the outdoor unit A.

And the outdoor unit A is the indoor unit C1+02,
In order to satisfy the required capability of C3, the output frequency of each inverter circuit is controlled according to the frequency setting signal fo sent.

In such an air conditioner, the input current to each inverter circuit in outdoor unit A is detected, and when the detected current exceeds a set value, it is determined to be a current abnormality and the output frequency of the corresponding inverter circuit is kept constant. The current is released to protect the inverter circuit.

In addition, when operating two compressors, 1, we periodically perform oil equalization operation that creates a certain difference in the output frequency of each inverter circuit, eliminating the imbalance of refrigerating machine oil (lubricating oil) in each compressor. Each compressor is protected.

(Problem to be solved by the invention) By the way, when two compressors are operated, there is usually no big difference in the output frequency of each inverter circuit, but since the current release is independent for each inverter circuit, the current release is When this happens, there will be a large difference in the output frequency of each inverter circuit. Moreover, this disparity occurs in various patterns, such as when there is a difference in the capacity (horsepower) of each compressor, or when the current release of each inverter circuit works simultaneously.

On the other hand, current release has priority over oil equalization operation, and if current release interrupts oil equalization operation, it becomes difficult to shift the frequency control appropriately after current release, making it impossible to obtain an oil equalization effect.

This invention was made in view of the above circumstances,
The purpose is to be able to reliably perform oil equalization operation without being affected by current release.
The object of the present invention is to provide an air conditioner that enables stable operation at all times.

[Structure of the Invention] (Means for Solving the Problems) Two inverter circuits that supply driving power to each compressor, and the output frequency of these inverter circuits are controlled according to the total required capacity of each indoor unit. means for periodically performing an oil equalization operation to provide a certain difference in the output frequency of each of the inverter circuits when two compressors are operated; and a current detector for detecting the input current to each of the inverter circuits. current release means for reducing the output frequency of the corresponding inverter circuit by a certain value when the detected current of the current detection means exceeds a set value; A means for setting the information shall be provided.

(Function) When the input current to the inverter circuit exceeds a set value, a current release is performed to reduce the output frequency of the inverter circuit by a certain value. At this time, the output frequencies of the other inverter circuits are set to the same value to eliminate differences in the output frequencies of each inverter circuit.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings. In the drawings, the same parts as in the drawings are designated by the same reference numerals, and their explanations will be omitted.

As shown in Figure 2, the outdoor unit A has a capacity of two units 11.
A variable compressor 1.2 is provided, and the compressor 1.2 is connected to a check valve 3.
, 4 are connected in parallel through each of them.

and an A array of compressors 1 and 2, a four-way valve 5, an outdoor heat exchanger 6, a heating expansion valve 7, and a cooling cycle forming check valve 8;
Liquid tank 9, electric flow rate adjustment valve 11.21.31
, a parallel body of cooling expansion valves 12, 22° 32 and heating cycle forming check valves 13, 23° 33, indoor heat exchanger 14,
24.34, Gas side on-off valve (electromagnetic on-off valve) 15.25,
35, the accumulator 10, etc. are successively connected to form a heat pump type refrigeration cycle.

Note that the cooling expansion valves 12, 22.32 each have temperature sensing cylinders 12a, 22a, 32a, and these temperature sensing cylinders are attached to the gas side refrigerant piping of the indoor heat exchanger 14, 24, 34, respectively. There is.

That is, the indoor heat exchangers 14, 24, and 34 are configured in parallel.

Further, during cooling operation, the refrigerant is caused to flow in the direction of the solid arrow shown in the figure to form a cooling cycle, and during heating operation, the refrigerant is caused to flow in the direction of the broken line arrow shown by the switching operation of the four-way valve 5 to form a heating cycle. ing.

In addition, an oil separator 4 is installed on the refrigerant discharge side piping of the compressor 1.
1 is provided, and an oil bypass pipe 42 is provided from the oil separator 41 to the refrigerant suction side pipe of the compressor 1. Further, an oil separator 43 is provided on the refrigerant discharge side piping of the compressor 2, and an oil bypass pipe 44 is provided from the oil separator 43 to the refrigerant suction side piping of the compressor 2.

The reference oil level levels 15 of the cases of the compressors 1 and 2 are communicated with each other through oil equalizing pipes 45, allowing refrigerating machine oil (lubricating oil) to flow between them.

The control circuit is shown in FIG.

The outdoor unit A includes an outdoor control section 50. This outdoor control section 50 is made up of a microcomputer and its peripheral circuits, and has external inverter circuits 51 and 52.
are connected.

The inverter circuits 51 and 52 rectify the voltage of the AC power supply 53, convert it into an AC voltage of a predetermined frequency by switching according to a command from the outdoor control unit 50, and supply it as driving power to the compressor motors LM and 2M, respectively. It is something to do.

Branching unit B includes a multi-control unit 60. This multi-control unit 60 is composed of a microcomputer and its peripheral circuits, and externally includes flow rate regulating valves 11, 21.3.
1 and an on-off valve 15, 25°35 are connected.

The in-group units C1, C2, and C3 are indoor control units 70.8
It has a value of 0.90. These indoor control units consist of a microcomputer and its peripheral circuits, and are externally connected to operation control units 71, 81.91 and indoor temperature sensors 72.8.
2.92 are connected respectively.

Here, a specific example of the outdoor control section 50 and its surroundings is shown in FIG.

The outdoor control unit 50 is a main microcomputer 10
0, inverter microcomputers 101, 102 for inverter drive control, and inverter drive circuit 10
3,104.

The inverter circuits 51 and 52 have current detection circuits 111 and 112 as means for detecting their respective input currents,
The detection outputs of these current detection circuits are supplied to inverter microcomputers 101 and 102.

The microcomputer 100 gives commands corresponding to the frequency setting signal fo from the branch unit B to the inverter microcomputers 101 and 102, and also changes the output frequency of the inverter circuits 51 and 52 using return signals from the inverter microcomputers 101 and 102. Sense it.

The inverter microcomputers 101 and 102 control the inverter drive circuits 103 and 104 according to commands from the microcomputer 100, and also control the inverter drive circuits 5 and 5 based on the detected current of the current detection circuits 111 and 112.
The output frequency of 1.52 is determined and the determination result is returned to the micro combi coater 100. Further, when the detected currents of the current detection circuits 111 and 112 exceed a set value, it is determined that the input terminal is abnormal, and current release control is performed to reduce the output frequency of the corresponding inverter circuit by a certain value.

The inverter drive circuits 103 and 104 drive the inverter 1[
Turn on the switching elements S51 and 52.

The inverter circuits 51 and 52 are turned off and output an alternating current voltage of a predetermined frequency.

Next, the operation in the above configuration will be explained.

It is assumed that all indoor units are currently performing cooling operation.

At this time, the indoor control section 70 of the indoor unit C1 calculates the difference between the temperature detected by the indoor temperature sensor 72 and the set temperature determined by the operation operation section 71, and requests a frequency setting signal fl corresponding to the temperature difference. Cooling capacity and multi-control unit 6
Transfer to 0.

Similarly, the indoor control section 80.9 of the indoor units C2 and C3
0 is also the frequency setting signal f2. f3 is transferred to the multi-control unit 60 as the required cooling capacity.

The multi-control unit 60 determines the required cooling capacity of each indoor unit based on the transferred frequency setting signal, and generates a frequency setting signal f corresponding to the sum total.

is transferred to the outdoor control section 50.

The outdoor control unit 50 receives the transferred frequency setting signal f.

Based on the number of operating compressors 1 and 2 and operating frequency (
The output frequency of the inverter circuits 51 and 52 is controlled.

In this case, the outdoor control unit 50 shifts from operating one compressor 1 to operating two compressors 1 and 2 as the total required cooling capacity increases.

Note that the multi-control unit 60 controls the indoor units C1+C2,
The corresponding flow r:L according to the required cooling capacity of C3.
The degree of superheating of the refrigerant is maintained constant by controlling the opening degree of the 21 regulating valve 11, 21.31 (7) and adjusting the flow rate of refrigerant to the indoor heat exchanger 14, 24.34.

By the way, when two compressors 1.2 are operated, the outdoor control section 50
Perform oil equalization operation periodically.

In this oil equalization operation, for example, the output frequency of the inverter circuit 51 is set to a command frequency (based on the total required cooling capacity).
, and the output frequency of the inverter circuit 52 is raised and lowered within a certain width around this central value, thereby creating a certain difference in the output frequencies of the inverter circuits 51 and 52.

In this case, when the output frequency of the inverter circuit 51 becomes higher than the output frequency of the inverter circuit 52, the case pressure of the compressor 1 becomes lower than the case pressure of the compressor 2, and the refrigerating machine oil of the compressor 2 passes through the oil equalizing pipe 45. It flows to compressor 1 and becomes hot. Conversely, when the output frequency of the inverter circuit 52 becomes higher than the output frequency of the inverter circuit 51, the case pressure of the compressor 2 becomes lower than the case pressure of the compressor 1, and the refrigerating machine oil of the compressor 1 flows through the oil equalizing pipe 45. It becomes easier to flow to the compressor 2.

Incidentally, after this oil equalization operation has been performed for a certain period of time based on the timing of the internal timer, the output frequency of the inverter circuits 51 and 52 is set to the command frequency, and normal operation is resumed.

On the other hand, the inverter microcomputers 101 and 102 of the outdoor control unit 50 monitor the detected current of the current detection circuit 111 and 112, and when the detected current exceeds the set value I2 shown in FIG. 4 and reaches the P region, This is determined to be an input terminal error.

When it is determined that the input terminal of the inverter circuit 51 is abnormal, the output frequency of the inverter circuit 51 is reduced by a certain value and current is released. This frequency reduction is performed with priority regardless of whether or not the oil equalization operation described in 2 is performed, and is performed every time the detected current is taken in until the detected current deviates from the P region. Then, the detection current is 1. , the output frequency of the inverter circuit 51 is maintained as it is, and when it drops to the O region below 1, the current release is changed to i.
and set the output frequency to the command frequency.

At this time, the microcomputer 100 controls the inverter circuit because the contents of the command to the inverter microcomputer 101 (command frequency) and the contents of the return signal from the inverter microcomputer 101 (output frequency of the inverter circuit 51) are different. 51 detects that the current is released, and immediately sets the output frequency of the inverter circuit 52 to the same value as the output frequency of the inverter circuit 51.

Furthermore, in the event of an input current abnormality in the inverter circuit 52, current is released to reduce the output frequency of the inverter circuit 52, and the output frequency of the inverter circuit 51 is immediately set to the same value as the output frequency of the inverter circuit 52. .

Furthermore, if an input current abnormality occurs in the inverter circuits 51 and 52 at the same time, the inverter circuits 51 and 52 also have input current abnormalities.
52, the output frequencies at the time of reduction are compared, and the lower output frequency is made to match the higher output frequency.

In this way, when current is released from at least one of the inverter circuits 51 and 52, the output frequency of the other inverter circuit is set to the same value as the output frequency at that time, eliminating the difference in the output frequency of each inverter circuit. As a result, even if the current release interrupts oil equalization operation,
Frequency control can be easily and smoothly shifted after current release. Therefore, the oil equalization operation can be reliably performed without being affected by the current release, and so-called oil rising in the compressor 1.2 can be prevented, and efficient and stable operation can be performed at all times.

Further, since an oil return path such as an oil separator is provided to the compressor 1.2, refrigerating machine oil can be efficiently recovered.

In addition, 1. Although the above embodiment has been described only during cooling operation, similar effects can be obtained during heating operation as well.

Also, although we explained the case where the indoor unit is a king-sized unit,
It is possible to implement the same method in the case of more than three units or three units.

In addition, the present invention is not limited to the above-mentioned embodiments, and various modifications can be made without changing the gist.

[Effects of the Invention] As stated above, according to the present invention, three inverter circuits supply driving power to each compressor, and the output frequency of these inverter circuits can be adjusted to the sum of the required capacities of each indoor unit. means for controlling the input current to each of the inverter circuits, means for periodically performing an oil equalization operation to provide a certain difference in the output frequency of each of the inverter circuits when the three compressors are in operation; A current detection means for detecting a current, a current release means for reducing the output frequency of the corresponding inverter circuit by a certain value when the detected current of this current detection means exceeds a set value, and a current release means for reducing the output frequency of the corresponding inverter circuit by a certain value when the current detected by the current detection means exceeds a set value; Since a means for setting the value is provided, the oil equalizing operation can be reliably executed without being affected by the implementation of the current release, thereby providing an air conditioner that always enables stable operation.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of the main parts of a control circuit in one embodiment of the present invention, FIG. 2 is a diagram showing the configuration of a refrigeration cycle in the same embodiment, and FIG. 3 is a diagram showing the configuration of the control circuit in the same embodiment. FIG. 4 is a diagram showing the relationship between the detected current and the set value in the same embodiment, and FIG. 5 is a diagram schematically showing the configuration of a conventional air conditioner. A...Outdoor unit, B...Branch unit, CI
+'C2, C-t...Indoor unit, 1.2...Variable capacity compressor, 50...Outdoor control section, 60...Multi control section, 70.80,9θ...Indoor control Section, 101
, 102... Inverter microcomputer, 11
1゜112...Current detection circuit (current detection means). Applicant's representative Patent attorney Takehiko Suzue, 111F Fees Figure 1

Claims (1)

[Claims] In an air conditioner consisting of an outdoor unit having two variable capacity compressors and a plurality of indoor units, two inverter circuits supplying driving power to each of the compressors;
Means for controlling the output frequency of these inverter circuits according to the total required capacity of each of the indoor units, and oil equalization operation that provides a certain difference in the output frequency of each of the inverter circuits when two of the compressors are operated. a current detecting means for detecting the input current to each of the inverter circuits, and reducing the output frequency of the corresponding inverter circuit by a certain value when the detected current of the current detecting means exceeds a set value. An air conditioner comprising current release means and means for setting the output frequencies of other inverter circuits to the same value upon current release.