JPS62299658A - Method of controlling operation of refrigerator - 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] 3. Detailed description of the invention a) Industrial application field The present invention combines the number control of a plurality of compressors and the rotation speed control of one of the compressors. The present invention relates to a method for controlling the operation of a variable capacity refrigeration system.

(1) Prior Art Conventionally, this type of refrigeration apparatus has been described in Japanese Patent Application Laid-Open No. 58-221349, etc., and has five configurations as shown in FIG.

To explain below, 30 is two compressors A connected in parallel.
, B, a condenser 31, an expansion valve 32, and an evaporator 33 are connected in sequence to form a refrigeration cycle. 34 is electrically connected to each of the compressors A and H, and is connected to the refrigeration cycle 3.
This is a controller that controls the number of operating units according to the load amount of o. Reference numeral 35 denotes a frequency variable device that is electrically connected only to the compressor B and controls the rotational speed of the compressor B in accordance with the load iK of the refrigeration cycle 30. Such a refrigeration system controls the rotation speed of only one compressor B among the plurality of compressors A and B.

The electric capacity of the frequency variable device is reduced to save power. P9 Problems to be Solved by the Invention However, the above configuration has the following problems, and improvements are desired.

The operation control of the above configuration is normally performed as follows.

For example, if the load on the refrigeration cycle 30 suddenly increases from a state in which the refrigeration system 30 is operated only with the compressor B whose rotation speed is controlled, and the capacity of the compressor alone cannot keep up with the load, first , the operating frequency of the compressor B is increased stepwise by the frequency variable device 35 to the upper limit frequency.

Thereafter, with the compressor temporarily stopped, the other compressor A is operated with commercial power, while the compressor B is operated again, and the compression fl! Capacity control is performed by increasing the operating frequency of aB to a frequency corresponding to the target load. That is, according to such an operation control method,
Since priority is given to controlling the rotation speed of compressor B, it is possible to follow gradual changes in the refrigeration load, but it takes time to control and cannot follow sudden changes in the refrigeration load as described above. delay.

There was a problem that it became difficult to stably control the rhinoceros temperature.

The present invention has been developed in view of these points, and provides a refrigeration system that can quickly control the capacity to match the target load amount without any time delay even in response to sudden changes as well as gradual changes in load. The purpose is to provide a method for controlling the operation of equipment.

Means for Solving the Problems The present invention comprises a refrigeration cycle by sequentially connecting a plurality of compressors, condensers, pressure reducing devices, and evaporators connected in parallel, and the refrigeration cycle is provided with a load detection means for detecting the amount of load, and the number of operating compressors is controlled according to a signal from this means, and a frequency variable device is provided to control one of the compressors according to a signal from the means. In a refrigeration system equipped with a control device that controls the rotation speed.

When the difference between the detected value detected by the load detection means and the preset value set in the control device is small, the rotation speed control of the compressor is given priority over the number control. When the difference in the number of compressors is large, control of the number of compressors is given priority over control of the number of revolutions.

(e) Effect The method for controlling the operation of a refrigeration system according to the present invention has the above-mentioned configuration.
For example, when the difference between the detected value detected by the load detection means and the preset value set in the control device is small, that is, when the load of the refrigeration cycle is changing slowly, Priority is given to controlling the rotation speed of the compressor in the refrigeration system, and the capacity of the refrigeration system is variably controlled to the target capacity. When a change occurs, by giving priority to controlling the number of compressors, the capacity of the refrigeration system can be brought roughly and quickly close to the target capacity.

For compressors whose rotation speed is controlled, after the above-mentioned number control has been carried out, fine frequency control can be performed until the target capacity is achieved, so there is no significant time delay even in the case of sudden changes in load. without arising.

Capacity can be quickly shifted to match the target load amount.

(f) Example Embodiments of the present invention will be described below with reference to the drawings.

1 has three compressors A, B, and C connected in parallel.

This is a refrigeration cycle configured by sequentially connecting a condenser 2, an expansion valve 3, and an evaporator 4. The three compressors A, B, C
The respective capacities are 5)P and 7.5)P.

10) A capacitor with a different capacity than P is used.

Reference numeral 5 denotes a pressure sensor attached to the low pressure side pipe of the refrigeration cycle 1. This sensor detects a low pressure value as the load amount of the refrigeration cycle, converts the detected value into an electric signal, and transmits the detected value to a control device 6, which will be described later. It is output to. Here, the compressors A and C are connected to a three-phase AC power source 9 via electromagnetic contactors 7 and 8, respectively, and the compressor B is connected to a
a frequency variable device 10 that varies in the range of Hz to 75Hz;
and is connected to a three-phase AC power source 9 via an electromagnetic contactor 11. 6 inputs the signal from the pressure sensor 5, and sends a signal corresponding to the difference between this input value and a preset setting value to the electromagnetic contactor 7.8.11 or the frequency transformer [
10 to control the ON-OFF of the contactor and the frequency of the frequency disguise mio, and control the number of compressors A and C according to the load of the refrigeration cycle 1, and also control the number of compressors A and C according to the load of the refrigeration cycle 1. This is a control device that controls the rotation speed of compressor B. Here, this control device will be explained in detail below based on FIGS. 2 and 3. First, as shown in FIG. 2, the control device 6 has set values for converging the low pressure PL within this range, that is, in addition to the upper limit value H and the lower limit value, there are also set values that are higher than the upper limit value H. A high maximum value HH,
A lower limit value LL, which is even lower than the lower limit value, is set, and the low pressure P is divided into five zones, namely, zone
・・P,, ≧HH, zone■・・・H≦PL (HH, zone■...L<PL<H% zone■...L≧PL)
LL, zone ■...PL≦LLK is divided. In addition, the control device includes HH, H, LlL as shown in FIG.
Pressure comparison circuit 2 consisting of comparators 12, 13, 14, and 15 set to four different values corresponding to each of L, variable resistors 16, 17, and fixed resistors 18, 19, 20, and 21.
2 is placed inside. To explain the operation of this circuit, first, when a detection signal from the pressure sensor 5 enters the circuit,
The detected signal is compared with each of the four comparators 12.13.14.15.

Based on these four comparison results, it is possible to detect which zone the detected pressure value is in, and also to output a control signal a as shown in the figure below.
, b, c, d, and e, and the ON-OFF control of the electromagnetic contactors 7, 8, and 11 and the frequency control of the frequency variable device 1100 are performed using these control signals.

Here, a general method of controlling the operation of the refrigeration system based on the operation of the control device 6 described above will be described.

This will be explained based on the flowchart shown in FIG.

First, the pressure value PL detected by the pressure sensor 5 is
Check whether it is higher than the maximum upper limit HH.

If it is high, the pressure value PL is in zone ■, and the difference from the target zone ■ is large, so priority is given to increasing the number of compressors A and C. At this time, the capacity of the refrigeration equipment after controlling the number of compressors is The operating frequency of the compressor B whose rotation speed is controlled is reset to OHz so that the rotation speed does not suddenly increase. Also, if it is low.

Next, check whether it is higher than the upper limit H. If it is higher than the upper limit H, the pressure value P1 is in zone ■.

Since the difference from the target zone (■) is small, priority is given to increasing the rotation speed of compressor B, but at this time, it is checked whether the compressor is operating at the upper limit frequency (75 Hz). Then, when operating at the upper limit frequency, the number of compressors A and C is increased. Further, if the pressure value PL is lower than the upper limit value H, then it is checked whether it is lower than the lowest limit value LL. If it is low, the pressure value PL is in zone (2) and the difference from the target zone (2) is large, so the number of compressors A and C is reduced. If it is high, then check whether it is lower than the lower limit. If the pressure value PL is high, the current operating state is maintained because the pressure value PL is in the target zone (zone 3). If it is lower than the lower limit value, the pressure value PL is in zone ■,
Since the difference from the target zone (■) is small, priority is given to reducing the rotation speed of compressor B, but at this time, it is checked whether the compressor is operating at the lower limit frequency (25 uz). And when operating at the lower limit frequency, compressor A.

Decrease the number of C units.

Next, the operation control method of the present invention will be explained in detail for each zone based on the flowcharts of FIGS. 5 to 8.

(AlWhen PL≧HH shown in Fig. 5, first, compressor A
, check whether C is both driving.

If you are driving both! 1'' The control device iL6 sends a frequency up signal to the frequency variable device 10 to increase the rotation speed of the compressor B. However, if the operating frequency of compressor B has already reached the upper limit frequency (75Hz), all compressor units A and B%C will be operating at maximum capacity, so any further increase in capacity will not be possible. cannot be done.゛Also, if even one compressor A or C is stopped, a signal is sent from the control device i16 to the electromagnetic contactor 7.8 to increase the number of operating compressors A or C. 'MJ controls are operated in order from the one with the smallest capacity. In other words, the compressor person is 5)P and the compressor C is 10)P.

The number of units is controlled by compressor A, → compressor C1 → compressor A.

It becomes C. Here, the compressor B whose number of revolutions is controlled is as follows.

In order to prevent the capacity from increasing rapidly after controlling the number of units, the operating frequency is reset to OHz. That is, in such a zone, since the difference between the pressure value P1 and the set value U is large, the number control of the compressors A and C is performed with priority over the rotation speed control.

fbl As shown in FIG. 6, it is checked whether H≦PL (when HH, compressor B is being operated at the upper limit frequency (75) 1z). If the frequency is not the upper limit frequency, the control device 6 sends a frequency up signal to the frequency variable device 10 to increase the rotation speed of the compressor B.

Also, if compressor B is already at the upper limit frequency.

The number of units is increased in the same manner as in the case of 1al above, and the pressure value PL and set value ■ are 5°.
Since the difference between the two compressors is small, the rotation speed control of the compressor B is performed with priority over the number control.

(When cL<PL<H, in this case, the pressure value is within the range of the set value (L-H), that is, in the target zone (■), so the current operation is continued as is.

(The flowchart in such a case is omitted) (dl When L≧PL>LL shown in Fig. 7, first check whether compressor B is being operated at the lower limit frequency (25Hz). If it is not the lower limit frequency, control is performed. A frequency down signal is sent from the device 6 to the frequency variable device 10 to reduce the rotation speed of the compressor B.

In addition, if compressor B has already reached the lower limit frequency, the number of compressors A and C is reduced, but the number control of compressors A and C is stopped in order from the one with the largest capacity. let That is, compressor A is 5)P, compressor C is 10H
) Therefore, one unit control is compressors A and C → pressure 1a machine C → compressor A. Also, if both compressors A%C have already stopped.

The operating frequency of compressor B is set to OHz, and the pressure m is also stopped. That is, in such zone (2), since the difference between the pressure value PL and the set value - is small, the rotation speed control of the compressor B is performed with priority over the number control.

tel When P, ≦LL shown in Fig. 8, first, compressor A
, C are both stopped.

If both are stopped, the control device 6 sends a frequency down signal to the frequency variable device 10 to reduce the rotation speed of the compressor B. However, if the operating frequency of the compressor B has already reached the lower limit frequency (25 Hz), the output frequency of the frequency transform &10 is set to OHz and the compressor B is also stopped. Further, if even one compressor A or C is operating, a signal is sent from the control device 6 to the electromagnetic contactor 7.8, and the number of compressors is reduced in the same manner as in the case of (dl) described above.

That is, in such zone ■, the pressure value PL and the set value (
Since the difference between compressors A and C is large, control of the number of compressors A and C is performed with priority over control of the rotation speed.

In this 5K, the operation control method of the refrigeration equipment of the present invention is based on the pressure value PL detected by the pressure sensor 5 and the control device 6.
(Highest limit value HH1 Upper limit value Lower limit value Lower limit value Lower limit value LL), and when the difference between the pressure value PL and the target set value (H, L) is small (e.g. When the pressure value PL is in zone ■ or zone ■, the rotation speed control of compressor B is given priority over the control of the number of compressors A and C, while when the difference is large (for example, when the pressure value PL is in zone or zone (2)], control of the number of compressors A and C is given priority over control of the rotational speed of compressor B.

As a result, 1. For example, when the difference between the pressure value PL detected by the pressure sensor 5 and the set value (H%L) is small, that is, when the load of the refrigeration cycle 1 is changing slowly, the Priority is given to controlling the rotation speed of one compressor B, and the capacity of the refrigeration system is variably controlled to the target capacity.

When the difference between the pressure value P and the set value (H, L) is large, that is, when the load of refrigeration cycle 1 changes suddenly, priority is given to controlling the number of compressors A and C. , the capacity of the refrigeration equipment can be brought closer to the target capacity more or less quickly. This is because it is only necessary to perform fine rotational speed control until the desired capacity is reached.

Even if there is a sudden change in load, the capacity can be quickly shifted to the target load without causing a large time delay.

This is clear from the explanatory diagram shown in FIG.
For example, in the same figure, assume that the load that corresponds to the capacity of the refrigeration equipment is 0 suddenly increases to a load that corresponds to the capacity. In this case, instead of the conventional control such as 0 → 0 → [F] → ■, control such as θ → 0' → ■, that is, control that gives priority to increasing the number of compressors A and C, should be performed. By.

The capacity of the refrigeration system can be quickly brought close to the target capacity. In addition, if the difference between the pressure value PL and the set value (H, L) is small, that is, H≦P, <HH and L≧PL.
In the case of
The capacity increases in the order →O, or decreases in the order O−+[F]→O→■.

(g) Effects of the Invention As described above, the uninvented operation control method reduces the rotation speed of the compressor when the difference between the detected value detected by the load detection means and the preset value set in the control gc position is small. While prioritizing control, when the difference between the detected value and the set value is large, priority is given to controlling the number of compressors, so the difference between the detected value and the set value is small and the load on the refrigeration cycle is reduced. When the change is gradual, priority is given to controlling the rotation speed of one compressor as before, and the capacity of the refrigeration system can be controlled to the target capacity. When there is a sudden change in the load on the refrigeration cycle, the capacity of the refrigeration system can be brought roughly and quickly closer to the target capacity by giving priority to controlling the number of compressors. (b) Compressors that are rotationally controlled can only be used by finely controlling the rotational speed until the target capacity is reached after the above-mentioned number control has been carried out, so it is difficult to avoid sudden loads. Even if there is a major change, the target capacity can be quickly shifted to without causing a large time delay. Thereby, capacity control of the refrigeration system can be performed stably.

[Brief explanation of the drawing]

1 to 9 show embodiments of the present invention, FIG. 1 is a configuration diagram of a refrigeration system, FIG. 2 is an explanatory diagram showing low pressure zone division, and FIG. 3 is a pressure comparison circuit of a control device. 4 is a flowchart showing a schematic operation control method of the refrigeration equipment, FIG. 5 is a flowchart when PL≧HH, and FIG. 6 is a flowchart when PL≧HH.
≦PL<HH flowchart, Figure 7 shows L≧PL>
FIG. 8 is a flowchart when PL≦LL, FIG. 9 is an explanatory diagram showing changes in capacity of the refrigeration system, and FIG. 10 is a configuration diagram of a conventional refrigeration system. 1... Refrigeration cycle, A, B, C... Compressor. 2... Condenser, 3... Expansion valve, 4... Evaporator 55... Pressure sensor, 6... Control device, 10
...periodic mantissa variable device. Applicant: Sanyo Electric Co., Ltd. (1 other person) Representative: Patent attorney Takuji Nishino (1 other person) Figure 4

Claims (1)

[Claims] (1) A refrigeration cycle is constructed by sequentially connecting a plurality of compressors, condensers, pressure reduction devices, and evaporators connected in parallel, and the refrigeration cycle is provided with a load detection means for detecting a load amount, A refrigeration system is provided with a control device that controls the number of compressors in operation according to a signal from the means, and also controls the rotation speed of one of the compressors using a frequency variable device according to a signal from the means. In the device, when the difference between the detected value detected by the load detection means and the preset value set in the control device is small, the rotation speed control of the compressor is given priority over the control of the number of compressors, while the detected value and the setting value are A method for controlling the operation of a refrigeration system, characterized in that when the difference between the two values is large, control of the number of compressors is given priority over control of the number of revolutions.