JPS62258965A - Refrigeration equipment - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a refrigeration system that is equipped with a compressor whose capacity is adjusted by an inverter and whose refrigerating capacity is variable, and in particular has an overcurrent protection function for the inverter. Concerning improvements to what has been done.

(Jumei's technology) Conventional J: This kind of refrigeration equipment, for example,
As disclosed in Publication No. 9-132771, a shrinking machine,
an inverter that adjusts the capacity of the compressor in multiple stages by changing the operating frequency of the compressor, and an overcurrent detection means that detects when overcurrent is flowing on the input side and output side of the inverter. When an overcurrent is detected by the overcurrent detecting means, the operating frequency of the compressor is changed and set to a lower value to lower the rotational speed of the compressor, and the droop control is performed. It is known that the inverter is effectively protected from overcurrent by suppressing the flow of overcurrent.

(Problem to be solved by the invention) By the way, as mentioned above, is the inverter overloaded? ! If the droop υ control is performed during distribution, after this droop control is finished,
It is necessary to increase the operating frequency of the compressor and return it to its original rotational speed.

In this case, when the refrigeration load is large, the rotational speed of the compressor is large, leading to a sudden increase in the rotational speed, and the durability and reliability of the compressor are reduced.

The present invention has been made in view of the above, and its purpose is to provide a refrigeration system in which the overcurrent protection function is improved by performing inverter droop control as described above, so that after the inverter droop control is completed, Increasing the operating frequency of the compressor, that is, increasing its rotational speed.1. 1. By controlling the compressor in stages, it is possible to prevent a sudden increase in the rotational speed of the compressor and improve its durability and reliability. .

(Means for Solving the Problems) In order to achieve the above object, the solving means of the present invention, as shown in FIG.
The present invention is based on a refrigeration system in which the capacity of the compressor (1) is adjusted to 1l11 in multiple stages by changing the operating frequency of the compressor (1). Then, there is an overcurrent detection hand a (55) that detects when an overcurrent flows through the inverter (3]), and the overcurrent detection hand! Droop control means (56) for controlling the inverter (31) is biased to reduce the operating frequency of the compressor (1) for a predetermined period of time when overcurrent is detected by (55). Roughly, the above droops! As soon as the elapsed time from the end of the droop control by the IIwJ means (56) is measured, the time measuring means (
and return control means (58) which receives the output of the time measuring means (57) and controls the inverter (31) to increase the operating frequency of the compressor (1) one step at a time when a set time elapses. ).

(Function) With the above configuration, in the present invention, when the inverter (31) is flowing with an excessive Wl flow, the operating frequency of the compressor (1) is controlled to decrease for a predetermined period of time by the droop control means (56), and the compressor (1) is Since the rotation speed of (1) decreases, the overcurrent does not continue, and the inverter is effectively protected from the overcurrent.

After the droop i control is finished, the elapsed time is measured by the time measuring means (57), and each time the measured time elapses by the set time, the operating direction of the compression v1 (1) is changed several times. *i! Since the rotation speed of the compressor (1) is raised step by step by tIIlal (58), the rotation speed of the compressor (1) is increased step by step, and its rapid increase is suppressed, resulting in improved durability and reliability of the compressor. I will do it.

(Example) Hereinafter, an example of the present invention will be described based on the drawings from FIG. 2 onwards.

Figure 2 shows the refrigerant piping system for multi-type and air conditioning/heating Vt units, where (A> is a commuter unit, (B), (C)).

(D) and (E) are different! It is an indoor unit that can be operated individually and is installed inside the outdoor 1f ICA). The exchanger (3), the heating expansion valve (4), and the main solenoid valve that opens only during heating operation (
SVM), a liquid receiver (5), and an accumulator (6).
VM) are connected to each other through refrigerant piping (7) so that refrigerant can flow through them.

On the other hand, each of the indoor units (B) to (E) has the same internal configuration, and the internal configuration of the indoor unit (B) will be described below. (The illustrations of the other indoor units (C) to (E) are also omitted.) Inside the indoor unit (8), there is a blower fan (1
0a), a cooling expansion valve (11), and an electric valve (EV) for individually allowing or stopping operation between each of the indoor units (B) to (E). The respective devices are sequentially connected through refrigerant pipes (1, 2), etc. so that refrigerant can flow therethrough.

1. Each of the above indoor units (8) to (E) is an outdoor unit (A)
are connected to each other by refrigerant pipes (13) in parallel to each other so that the refrigerant can circulate, and when the outdoor heat exchanger (3) is frosted during cooling operation or heating operation, the four The refrigerant in the compressor (1) can be circulated as shown by the solid line arrow in the figure by switching the path switching valve (2) as shown by the solid line in the figure.
As a result, the heat absorbed from the blank air by the indoor heat exchanger (10) is repeatedly radiated to the outside air by the outdoor heat exchanger (3), and the blank is cooled, and the outdoor heat exchanger (3) Defrost growing frost. On the other hand, during heating operation, the four-way switching valve (2) is switched as shown by the broken line in the figure, and the refrigerant is circulated as shown by the broken line arrow in the figure, thereby heating the blank space by transferring heat in the opposite direction. is configured to do so.

In addition, inside the above-mentioned outdoor unit (A>), there is an outdoor heat exchanger (3
), a heating auxiliary condenser (15) is attached along the heating auxiliary condenser (15), and the heating auxiliary condenser (15) is interposed in the middle of a bypass passage (16) that branches from immediately downstream of the compressor (1). During heating operation, part of the heat of the high-temperature refrigerant from the compressor (1) is radiated around the outdoor heat exchanger (3) to suppress frost formation. Generally speaking, in order to maintain the degree of superheat of the refrigerant at a predetermined value, the liquid pipe (
7) and the gas pipe (7) on the upstream side of the accumulator (6), an injection passage (17) is provided, and a superheat degree regulating solenoid valve (SVT) is provided in the middle of the injection passage (17). and an expansion valve (18) are interposed, and when the superheat degree regulating solenoid valve (SVT) is opened, the gas pipe (7) is inserted through the injection passage (17).
The degree of superheat of the refrigerant is maintained at a predetermined IC by increasing or decreasing the amount of liquid refrigerant returned to the refrigerant with an expansion valve (18).

In addition, the gas pipe (7) between the four-way switching valve (2) and the outdoor heat exchanger (3) and the gas pipe (7) upstream of the accumulator (6) are connected to a hot gas passage (20). An expansion valve (21) is interposed in the middle of the hot gas passage (20), and a part of the refrigerant flowing to the outdoor heat exchanger (3) is transferred to the hot gas passage (20) during cooling operation. By returning the air to the suction side of the compressor (1) through the air, the difference in air conditioning capacity between cooling operation and heating operation is adjusted. Further, the upstream and downstream sides of the series circuit of the heating expansion valve (4) and the main solenoid valve (SVM) are communicated through a liquid relief passageway (22), and two capillary tubes ( 23
), (24), and a high-pressure control valve (25) that opens when the high pressure of the refrigerant rises is interposed between them. When the high pressure rises, the liquid refrigerant in the liquid pipe (7) is returned to the downstream side of the heating expansion valve (4) through the liquid relief passage (22) to prevent the high pressure from occurring.
I'm trying to prevent it from rising. In addition, in the external unit (A), (26) is on the discharge side of the compressor (1)! ! ! The oil separated by the oil separator (26) is returned to the upstream side of the accumulator (6) through an oil return passage (27) communicating with the lower part of the oil separator (26). Also, (H
PS) is a high pressure switch for protecting the compressor (1) that detects the pressure of refrigerant discharged from the compressor (1), (PS19)
When the refrigerant pressure from the compressor (1) is a predetermined pressure (for example, 19K)
This is a pressure switch that opens when ff/CIi> or more, and is for blowing hot air from the beginning when the heating operation is restarted after the defrosting operation of the outdoor heat exchanger (3) is completed.

Moreover, FIG. 3 shows the internal configuration of the operation control circuit (30) provided in the above-mentioned external unit (1). The operation υ control circuit in the same figure (3
0) is connected to an inverter (31) that allows the capacity of the compressor (1) to be varied in a plurality of stages (for example, six stages) so as to be able to send and receive signals.

Moreover, inside the operation control circuit (30), a control CPU is provided.
(32) is programmed, and the control CPU (32) is connected to the inverter (31) via an interface (33), and the control CPU (32) sends six types of signals to the inverter (31). Frequency setting signal (30, 40, 5
0,60,70゜75ttz > and run/stop signals are output to increase or decrease the capacity of the compressor (1), and the trip status and droop status signals of the inverter (31) are respectively used for control. It can be input to CPtJ (32).

Furthermore, the control CPU (32) receives detection signals from an outside air sensor (34) that detects the outside air temperature and a coil temperature sensor (35) that detects the coil temperature of the outdoor heat exchanger (3). The pressure signal from the pressure switch (PS19) shown in FIG. 2 is inputted via the interface (38). Also °, control CPU (32)
In this case, each of the indoor control circuits (40) to (43) of the four indoor In (B) to (E) shown in Fig. 2 mutually send operation control signals such as operation command signals and thermo ON signals in each room. They are connected via transmitting/receiving sections (44) to (47) to exchange signals.

The E operation control circuit (30) includes an inverter (
A normally open contact (52) that allows or stops power supply to (31)
G-1>, the solenoid valve (2O8> of the four-way switching valve (2)), and the outdoor fan motor (52Fo) for driving the blower fan (3a) of the outdoor heat exchanger (3). ), the main solenoid valve (SVM), and the superheat control solenoid valve (SVT) are connected to each other, and normally open contacts (Ryl-1) to ( Five relays (Ryl) to (RV5) each having a relay driver (Ry5-t) are connected to the control CPU (32) via a relay driver (48)', and the control CPU (32) The O\-0FF control of five relays (Ryl) to (Ry5) by the O\-0FF control controls the operation of the compressor (1), /P soil, cold/warm switching, and operation and stop of the outdoor fan (3a). , refrigerant flow control. In Fig. 3, (49) indicates operation 11.
This is a power supply section for the No. 11 control circuit (30).

Next, the operation of the control CPU (32) will be explained based on the flowcharts shown in FIG. 4 and subsequent figures. Starting from FIG. 4 (a), after initializing the memory etc. in step S1, in step S2 the outside air temperature signal from the outside air sensor (34) and the outdoor coil temperature signal from the coil temperature sensor υ (35) are input. , the pressure signal of the pressure switch (PS19), and each! Operation command signals from internal control circuits (40) to (43),
The thermometer 0\'' signal etc. is input and transmitted, and step S3 also determines whether it is a cooling request or a heating request.After that, in step S↓, each blank machine (B) to (E) is operated. It is determined whether a command signal has been received or not, and if YES, indicating that a command signal is being received from one or more units, the driving flag DF is set to "1" in step S5, while if no, the driving flag DF is set to "1" in step S6. ``Make oF ro'J.
゛Then -, in step S7, it is cooled/! ? ! If the operating state is determined to be heating operating state, from step S8 onwards, 1゛1''2''□'a>(7)! ! tHiEti°7
゛“°＠9 Pot start operation (full mother operation of K reduction I! (1)) to ensure hot air blowing at the beginning of restarting operation.
Take measures to do so. However, in step S8, it is determined whether or not the defrosting operation of the outdoor heat exchanger (3) has ended, and □
If YES at the end, set the hot star drag H3F'' to "1"(H8F=1>) in step $9 only if □.

After that, in step Sho', during hot start operation with H8F=1, the pressure switch (P
A high pressure increase of the refrigerant is determined based on the state of step S19), and only in the case of NO during the opening operation when the high pressure has increased to 19 KJ/art, step S1 is executed to complete the bottom start operation.
2 returns H8F□=0.

After that, from step S13 onward in FIG. 4(b), in order to perform start mode operation (described later) for a predetermined period of time at startup, the start mode flag SMF is set in step S13.
, (“1” at startup) and determines the state of SMF=1 Y
Only when the ES is started, the timer TM11 is measured in step 814, and in step SIs, Y for T~111≧60 minutes is determined.
After the ES predetermined time has elapsed, in step 816 the TM11
After resetting, in step 817, the state is returned to S~IF=O to end the start mode operation. In addition, even within the predetermined time period when TMl 1 < 60 minutes (No in step S's), when the thermo signal from any blank machine (8) to (E) is OFF in one stage in step Sea (during light load). If the answer is No, the process returns to step Say and sets SMF=O in order to immediately shift to normal operation.

Subsequently, from step S19 onwards, measures are taken to switch the operating mode in order to correct the air conditioning capacity according to the outside temperature. That is, in step SI9, first, the region to which the outside air temperature from the outside air sensor (34) belongs is determined. Here, during cooling operation, this region is 29°C and 30°C, as shown in Figure 8.
When the differential picture is used between In addition, during heating operation, as shown in Figure 9, when the differential range cell value is between 9°5°C and 10.5°C, the low humidity region is the rHJ region, and the high temperature region is the rHJ region. "L" @ thief. and,
In the case of NO when the outside air temperature is in the rLJ region, that is, when the air conditioning capacity is increasing, the H mode flag)-IMF is set to "O" (HM
F=O). In addition, even in the case of YES in the rHJ region, when all the thermo signals from the indoor units in operation in step S21 are OFF in the first stage (during light load), the HM
While F=O, in other normal times, HMF=1 is set in step S22 to ensure the set air conditioning capacity.

Further, in step S23, it is determined whether cooling/warming is required, and in step S24, it is determined whether or not the empty pot heat exchanger (3) is in defrosting operation, and during cooling operation and defrosting operation, step S2!
In step S26, the four-way switching valve (2) is switched to the cooling cycle side in Step S26 during the heating operation except for the above-mentioned defrosting operation.
After switching the four-way selector valve (2) to the heating cycle side,
In order to measure the elapsed time from the time when the number of operating indoor units changes, in step S27, the timer T~112 sets the time δ.
1 measurement is performed, and in step 828, the timer TM12 is set to determine whether the prohibition time (for example, 3 minutes) for increasing the operating frequency of the compressor (1) has elapsed, and if YES for TM12≧3 minutes, In step S29, the control permission flag TM12F is set to "1" (TM12F=1) to permit the control to increase the operating frequency (capacity increase control of the compressor (1)), and then the process proceeds to step S3D. In the case of NO for <3 minutes, the process directly proceeds to step 830 in order to still prohibit the increase control of the operating frequency.

Thereafter, in step 830, the value of the operation flag DF is determined, and when DF=O (No), the operation of the compression chamber (1) and the empty bowl blower fan (3a) is stopped in step S31, and the main solenoid valve (SVM), superheat control solenoid valve (SVT
), and also outputs a frequency setting signal of the stop aunt and rOJ value to the inverter (31), and then proceeds to step S2.
Return to. On the other hand, when operating with DF=1, Fig. 4 (
Proceed to step Sx of c) and select an appropriate operation mode.

That is, in step 332 of FIG. 4(c), SMF=1
In the case of YES in step S33, the process proceeds to start mode operation, and in the case of YES in step S33 where HMF=1, the process proceeds to H mode operation, while in the case of No in HMF=O, the process proceeds to H mode operation. These 3f! The operation modes are preset as shown in the table below according to the number of operating indoor units (B) to (E). In the start mode (S), the H Frequency setting signal value (that is, air conditioning capacity) to the inverter (31) than the mode (H)
is set higher, and in L mode (L), in order to reduce the air conditioning capacity, it is set lower as the number of operating vehicles increases compared to +(mode (1-f)).

[Now, to specifically explain each operation mode, in the start mode operation, steps STI to ST are performed as shown in Fig. 5.
Determine the number of indoor units that are outputting the thermo ON signal in step 3, and
In the case of one machine, set the required frequency setting signal f to 30H7G, : in step ST↓, and in the case of two machines, step STs
to 50H2, and if there are 3 units, to 60H in step ST6.
Set each to 2. In addition, if the number of vehicles in operation is 4,
Furthermore, in step ST7, a distinction is made between the cooling operation and the heating operation, and when the @male operation is in progress, the region to which the outside air temperature belongs is determined in step ST8, and when it is in the "H" region in FIG. 9, step ST9 is performed. At 75Hzf,: set suru, while rLJ
At the end of the fI range, steps S=, +o are set to 601-1z in order to reduce the air conditioning capacity.

In addition, during cooling operation, the region to which the outside air temperature belongs is determined in step 5T11, and as shown in FIG. Sometimes, the required frequency setting signal f is set to 70H2 in step 5TI2, while ? When the temperature is in the 5-temperature side chain region, the air conditioning capacity is set to 60 Hz in step 5TIG.

In addition, in H mode operation, as shown in FIG. 6, the number of indoor units that are outputting the thermo ON signal is determined in steps SH1 to SH3, and if there is one indoor unit, the required frequency setting signal f is determined in step 5)-14. is set to 30H2, and if there are two machines, it is set to 40H2 in step 5145, and if there are three machines, it is set to 50H2 in step SH6. Also, the number of vehicles in operation is 4.
In the case of an air conditioner, it is roughly determined whether it is cold or @ in step SH7, and when the heating operation is in progress, the required frequency setting signal f is set to 75H2 in step S's, while during the cooling operation, the required frequency setting signal f is set to 75H2. 19, when the outside air temperature is in the low temperature region of FIG. 10, step S+tn is 70H2.
Then, when the temperature is in the high temperature region, the air conditioning capacity is set to 60H2 in step 5)-111 in order to reduce the air conditioning capacity. Roughly,
In L mode operation, as shown in FIG.
, SL2 determines the number of operating indoor units, and in the case of one or two indoor units, the required frequency ε constant signal f is set to 3 in step SL3.
Set to 0Hz, and if there are 3 devices, step S
40H2 with L4, and 6 with step SL5 in case of 4 units.
0H2(,: To be set.

After the required frequency setting signal f@82 to the inverter (31) is determined in this way, in step 334 of FIG. It is determined whether H8F=1 or not, and when the heating operation is restarted when H8F=1 is YES, the required frequency signal @r is set to the maximum regardless of the number of operating indoor units in step Sya, giving priority to the above three operation modes. The value is set to 75 Hzk:iff, and the compressor (1) is set to a hot stunite operation mode in which the compressor (1) is operated at its full capacity.

Next, in step 336, it is determined whether the restart prohibition flag TM9F-1 of the compressor (1) is set, and at the same time, in step S37, it is determined whether or not the required frequency signal f=o. TM
9F=O and f≠O during No operation, step 83B
Capacity of compressor (1) can be controlled with 5 COF rIJ
I, Knee (COF-1> I did it (D, Step S!)
3, and from step 83B onwards, the inverter (31)
Control drooping during overcurrent flow.

□In other words, in step Ss, it is determined whether or not there is a droop request signal (overcurrent detection signal) from the inverter (31), and when the droop request signal is received (YES), step S
Set the droop control flag SKF to "1" with @ (SKF=1
) After that, since 5KF=1 is YES in step S41 of FIG. 4(d), the value of the requested frequency signal is roughly determined in step S42. In step 343, the set frequency times $112 is forcibly reduced by 71 to H2=50 to lower the rotational speed of the compressor (1). Step S44
Then set the control permission flag TM12F to TM12F=O,
In addition, the timer TM12 is set to 7M12-0 in step S6.
Proceed to step 2.

Then, when requesting the end of the droop control in step S (No) in which the droop request signal is no longer received in FIG.
Therefore, in step 84G, this SKF is returned to O, and the control capacity flag TM12F@:
Set TM12F to grave O, and set timer TM12 to 7M12=
After resetting to O, in step S47, the value of the requested frequency multiplication @f is divided into 711, and NO of f -60 or 75H2 is set.
When a high air conditioning capacity is required, the droop return flag SKF' is set to SKF'=1 in step Sas in order to increase the operating frequency of the compressor (1) after the droop control is completed, as shown in FIG. 4 above. While proceeding to step S41 of (d),
If NO in the non-dripping control of 0, immediately proceed to step S41.
Proceed to.

After that, in step 841, since it is the end of the NO drooping control 11 with 5KF=O, the value of the drooping return flag SKF' is determined in step S49, and in the case of NO drooping control with SKF' = 0, step After S62, the set frequency multiplication @H2 is immediately controlled to match the required frequency multiplication @f.

On the other hand, when returning to normal operation after the droop control is completed with SKF' = 1 in step Sas, step S
50 to determine the value of the required frequency signal f, f=60 or 7.
5 is NO, so roughly in step S51 the value of the operating frequency upper control permission flag TM12F is determined, and the increase control prohibition time (for example, 3
minute), the process immediately proceeds to step 362 without setting the set frequency signal H2 to the maximum value, while the TM1
When control is permitted with YES (2F=1), the control permission flag TM12 is set in step S52 to measure the elapsed time.
TM12F=O, and set timer TM12 to T.
After setting M12=O, the value of the current setting frequency signal H2 is determined in step S53, and if H2=50\0, the frequency is increased by one level to Hz=60 in step 854. on the other hand,
In the case of YES at Hz=60, roughly step S55
After increasing 1a to Hz = f = 75, if f < 60 (YES in step S50), the drooping return flag SKF' = O is returned in step 856, and the process proceeds to step S62.

On the other hand, in step S36 of FIG. 4(c) above, T~19F
In the case of YES with =1, or Y with f=O in step S37.
When the compressor (1) is stopped in the case of ES, step S5
After setting the drooping control flag SKF to SK'=O in step 7 and returning the drooping return flag SKF' to SKF'=O in step 358, all is set in step S59 of FIG. 4(d).
Determine the value of the tXrJ enable flag COF, and if control is possible (YES with C0F=1), set C0F=O in step Sso.
At the same time, the setting frequency signal H2 is set to Hz=O to stop the operation of the compressor (1), and the restart prohibition flag TM9F is set to TM9F=1, and in step 361, the In order to prohibit the increase control of the operating frequency, TM12F=O is set and the timer TM12 is reset to TM12=O. On the other hand, step 85
N when control of C0F=O is prohibited at 9.

In this case, the process immediately proceeds to step S62.

After that, in step 362, the capacity of the compressor (1) is controlled, that is, the capacity of the compressor (1) is increased or decreased by making the set frequency signal t (l) to the inverter (31) match the required frequency signal f. In step S63, the control permission flag TM12F is set to O to measure the subsequent elapsed time, and the timer TM12 is reset to rOJ, and the process proceeds to step S64 in FIG. 4(d).

Thereafter, in steps Sb4 and subsequent steps in FIG.
4, the inverter relay (52C) is turned on and the compressor (1) is adjusted to the capacity according to the required frequency setting signal f using the inverter (31).

In addition, in step S65, it is determined whether or not control is possible after the restart standby time (for example, 3 minutes) has elapsed after the compressor (1) is once stopped, and when the compressor (1) is No. when control is prohibited, etc. When stopped, the outside blower fan (3a) is stopped in step S67, and even when control is possible, the empty bowl heat exchanger (3a) is stopped in step S67.
During the defrosting operation in step 3), the outside blower fan (3a) is stopped, and at other times, the empty pot blower is turned off in step Sm. hmm(
3a) is rotated. Roughly speaking, in step S69 it is determined whether the air conditioner is in cooling mode or in vi mode, and in step S70 it is determined whether or not the empty pot heat exchanger (3) is in defrosting operation.
In Step 1, it is determined whether control is possible or not, and in Step 372, the main solenoid valve (S
Otherwise, the main solenoid valve (SVM) is opened in step 373. In addition, it is determined in step S74 whether or not control is possible, and if the answer is YES when control is possible, the superheat degree regulating solenoid valve (SVT) is opened in step S75, while when control is prohibited, step S76 is performed. The closing operation is performed and the process returns to step S2.

Therefore, in the operation flow shown in FIG. 4 above, step S
39 constitutes an overcurrent detection means (55) for detecting when an overcurrent flows through the inverter (31), and steps 840 to 543 detect an overcurrent caused by the overcurrent detector a (55). At the time of detection, the operating frequency of the compressor (1) (setting frequency signal to the inverter (31) ((
A droop control means (56) is configured to lower the value of 2) from "60" or "75" to Hz=r50J while receiving the droop request signal. Also, in steps 344 and S27 to S29, when the drooping control is finished,
◆ Repeatedly measure the time period (for example, 3 minutes) during which the compressor operating frequency is prohibited from increasing, using timer TM12.
Time 81 f step (57) for measuring the elapsed time from the end of the droop control by the droop control means (56)
At the same time, through steps 351 to S55, the operating frequency of the compressor (1) is increased one step at a time from Hz = 50 at the elapsed time of the set time (operating frequency increase prohibition time (3 minutes)). This constitutes a return control means (58).

Therefore, in the above embodiment, the inverter (31
) When there is no overcurrent flowing through the compressor (1), the capacity of the compressor (1) is reduced depending on the number of Miyauchi machines in operation, so that the air conditioning capacity and empty air conditioner are constantly maintained. ! ! ! 1 load, and each room is comfortably air-conditioned.

Now, if an overcurrent flows through the inverter (31) in this state, the value of the operating frequency of the compressor (1) (that is, the set frequency 1-1z of the inverter (31)) becomes Hz = 6.
0 or 75, droop control is performed by the droop control means (56), and the compressor (1
) is forcibly lowered to H2=50, thereby reducing the rotational speed of the compressor (1) by that amount and suppressing overcurrent of the inverter (31).

After that, the number of blank machines in operation decreases with the droop control of the inverter (31) completed, and the required frequency signal f becomes "6".
When the Δ2 constant frequency signal H2 is set to decrease to mr (W4<f = 50.40 or 30), the rotation speed of the compressor (1) is maintained or The air conditioning capacity responds well to changes in the total air conditioning load without delay.

On the other hand, when the number of operating blank machines increases and the required frequency low @f is changed to "60" or "75", the operating frequency increase control prohibition time measured by the interval measuring means (57) ( 3 minutes), the set frequency signal H2
is raised by one step from H2750 to H2=60 by the first stage of return control (58), and after that, the transition at f=75 becomes 1-IZ=1-IZ= at the time when the uplink prohibition time (3 minutes) has elapsed again. 75 is set as an old dog. As a result, the number of blank machines in operation was large, and the required frequency signal, "F-75
If set to , the increase range of the rotation speed of the compressor (1) will be a wide increase range corresponding to r50JHz - r75JHz, but the increase in rotation speed will be prohibited during the operation frequency increase control time (3 minutes) Since it is carried out in stages every time, an increase in the rotation speed of 4 is prevented, and therefore the pressure is 16! <1) Durability,
Reliability can be improved.

In the above embodiment, the droop control of the inverter (31) is limited to the case where there is a large number of blank machines in operation < f = 60°75), but in other cases, overcurrent control is applied regardless of the number of blank machines in operation. Of course, droop control may be performed during distribution. Further, in the above embodiment, the present invention is applied to an air conditioner, but the present invention can be applied to any type of refrigeration device.

(Effects of the Invention) As explained above, according to the refrigeration system of the present invention, after the droop control a for overcurrent protection of the inverter for controlling the capacity of the compressor, the increase in the rotation speed of the compressor is controlled at a predetermined level. Since the rotation speed is prevented from increasing rapidly by performing the rotation stepwise, it is possible to improve the durability and reliability of the compressor.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of the present invention. Figures 2 to 10 show embodiments of the present invention, and Figure 2 is a refrigerant piping system diagram applicable to multi-type air conditioning equipment;
Figure 3 is a block diagram showing the internal configuration of the operation control circuit.
FIG. 8 and FIG. 9 are flowcharts showing the operation of U. FIG. 8 and FIG. 9 are diagrams showing operation mode switching regions during cooling operation and heating operation, respectively. FIG. 10 is a diagram showing frequency signal value switching regions during cooling operation. . (1)... Compression chamber, (30)... Operation $ control circuit,
(31)...Inverter, (32)...Control CP
(55)... Overcurrent detection means, (56)... Droop control means, (57)... Time ε4 measuring means, (58)...
・Return control means.

Claims (1)

[Claims] (1) In a refrigeration system in which the operating frequency of the compressor (1) is changed by the inverter (31) to control the capacity of the compressor (1) in multiple stages, the inverter (31)
1) Overcurrent detection means (
55), and droop control means (56) for controlling the inverter (31) to reduce the operating frequency of the compressor (1) for a predetermined period of time when the overcurrent detection means (55) detects an overcurrent. and a time measuring means (57) for measuring the elapsed time from the end of the droop control by the droop control means (56), and the time measuring means (57).
The compressor (1) receives the output of
The above inverter (3) increases the operating frequency one step at a time.
1). A refrigeration system characterized by comprising: a return control means (58) for controlling 1).