Control device, pump system and program

Abstract

When an inverter pump and a constant speed pump are used in combination, the power required for the operation of the inverter pump and the constant speed pump is reduced without using a flow meter that measures the flow rate of refrigerant discharged from the inverter pump. [Solution] The control device includes an inverter-equipped pump, the flow rate of which can be changed by inverter control, and a constant-speed pump, the flow rate of which is constant, connected in parallel to a refrigerant circuit. The control device includes an acquisition unit that acquires the frequency at which the inverter-equipped pump operates and the power consumption consumed by the inverter-equipped pump, and a control unit that controls the operation of the inverter-equipped pump and the constant-speed pump based on the relationship between the power consumption of the inverter-equipped pump and the shut-off power consumption consumed by the inverter-equipped pump when the discharge port is closed and the pump is operated at the above frequency.

Description

[Technical field]

[0001] The present invention relates to a control device, a pump system, and a program. [Background technology]

[0002] 2. Description of the Related Art Conventionally, there exists a cooling device that circulates a refrigerant through a refrigerant circuit using a plurality of pumps installed in parallel, and cools an object to be cooled by the refrigerant circulating through the refrigerant circuit. For example, Patent Document 1 discloses a cooling device including an evaporator, a condenser that dissipates heat from a refrigerant supplied to the evaporator to cool the refrigerant, and a plurality of pumps that provide driving force for circulating the refrigerant in a refrigerant circuit that connects the evaporator and the condenser in a ring shape. In this cooling device, the operation and stop of each of the plurality of pumps is individually controlled. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-24672 A Summary of the Invention [Problem to be solved by the invention]

[0004] When circulating refrigerant through a refrigerant circuit using multiple pumps, in order to adjust the flow rate and pressure of the refrigerant in the refrigerant circuit, a pump with an inverter, whose discharge flow rate can be changed by inverter control, and a constant speed pump, whose discharge flow rate of refrigerant is constant, may be used in combination. When using an inverter pump and a constant speed pump together, if the frequency of the inverter pump is excessively low, the refrigerant discharge pressure of the inverter pump may become significantly lower than the refrigerant discharge pressure of the constant speed pump. In this case, the inverter pump may not discharge refrigerant even though the inverter pump is operating, and the power consumption required to operate the inverter pump may be wasted. Here, by using a flow meter that measures the flow rate of the refrigerant discharged from the pump, it is possible to detect a state in which the inverter-equipped pump is not discharging the refrigerant even though the inverter-equipped pump is operating. However, since it is necessary to install a flow meter for each of the multiple pumps, the cost tends to be high.

[0005] An object of the present invention is to reduce the power required to operate an inverter pump and a constant speed pump when both are used in combination, without using a flow meter to measure the flow rate of refrigerant discharged from the inverter pump. [Means for solving the problem]

[0006] The invention described in claim 1 provides a refrigerant circuit in which an inverter-equipped pump capable of changing the flow rate of a discharged refrigerant by inverter control and a constant-speed pump whose discharged flow rate is constant are connected in parallel, the refrigerant circuit comprising: an acquisition unit that acquires a frequency at which the inverter-equipped pump operates and power consumption consumed by the inverter-equipped pump; and a control unit that controls operation of the inverter-equipped pump and the constant-speed pump based on a relationship between the power consumption of the inverter-equipped pump and shut-off power consumption consumed by the inverter-equipped pump when the discharge port is closed and the pump is operated at the frequency. When the power consumption of the inverter pump is equal to the shutoff power consumption when the inverter pump is operated at the frequency, the control unit determines that the refrigerant is not being discharged from the inverter pump, and controls the operation of the inverter pump and the constant speed pump so as to reduce the sum of the power consumed by the inverter pump and the constant speed pump. It is a control device. The invention described in claim 2 is the control device described in claim 1, wherein the cut-off power consumption when the inverter-equipped pump is operated at the frequency is calculated from the standard power consumption consumed by the inverter-equipped pump when the refrigerant discharge rate by the inverter-equipped pump is zero, the frequency, and the inverter efficiency of the inverter-equipped pump. Claim 3 In the invention described in the above, the refrigerant circuit is connected to a plurality of the constant speed pumps, and the control unit is configured to determine the power consumption of the inverter-equipped pump. When the inverter-equipped pump is operated at the above frequency, reducing the number of the constant speed pumps discharging the refrigerant when the power consumption is equal to the shutoff power consumption; Claim 1 The control device is as described above. Claim 4The invention described in the above relates to a refrigerant circuit in which a refrigerant circulates, a pump with an inverter connected to the refrigerant circuit and capable of changing the flow rate of the refrigerant discharged to the refrigerant circuit by inverter control, a constant speed pump connected to the refrigerant circuit in parallel with the pump with inverter and discharging a constant flow rate of the refrigerant to the refrigerant circuit, and a control device that acquires a frequency at which the pump with inverter operates and power consumption consumed by the pump with inverter, and controls operation of the pump with inverter and the constant speed pump based on a relationship between the power consumption and a shutoff power consumption consumed by the pump with inverter when the pump with inverter operates at the frequency with a discharge port closed. When the power consumption of the inverter pump is equal to the shutoff power consumption when the inverter pump is operated at the frequency, the control device determines that the refrigerant is not being discharged from the inverter pump, and controls the operation of the inverter pump and the constant speed pump so as to reduce the sum of the power consumed by the inverter pump and the constant speed pump. It is a pump system. Claim 5 The invention described in the above provides a refrigerant circuit in which an inverter-equipped pump capable of changing the flow rate of the discharged refrigerant by inverter control and a constant-speed pump whose discharged flow rate is constant are connected in parallel, the invention comprising a function for acquiring a frequency at which the inverter-equipped pump operates and a power consumption consumed by the inverter-equipped pump, and a function for acquiring a frequency at which the inverter-equipped pump operates and a power consumption consumed by the inverter-equipped pump based on a relationship between the power consumption of the inverter-equipped pump and a shut-off power consumption consumed by the inverter-equipped pump when the discharge port is closed and the inverter-equipped pump is operated at the frequency, When the power consumption of the inverter pump is equal to the shutoff power consumption when the inverter pump is operated at the frequency, it is determined that the refrigerant is not being discharged from the inverter pump, and the total power consumed by the inverter pump and the constant speed pump is reduced. The program is for realizing a function of controlling the operation of the inverter-equipped pump and the constant speed pump. Effect of the Invention

[0007] According to the present invention, when an inverter pump and a constant speed pump are used in combination, the power required to operate the inverter pump and the constant speed pump can be reduced without using a flow meter to measure the flow rate of refrigerant discharged from the inverter pump. [Brief description of the drawings]

[0008] [Figure 1] 1 is a diagram showing a schematic configuration of a pump system to which the present embodiment is applied; [Diagram 2] FIG. 2 is a block diagram showing an example of a functional configuration of a control device to which the present embodiment is applied. [Diagram 3] FIG. 2 is a diagram showing a schematic configuration of a pump system used in the measurement. [Figure 4] 1 is a graph showing a relationship between the power consumption of an inverter-equipped pump, the shutoff power consumption of the inverter-equipped pump, and the flow rate of a refrigerant, and the frequency of the inverter-equipped pump. [Diagram 5] 6 is a graph showing the relationship between the power consumption of an inverter pump and a first constant speed pump, the flow rate of a refrigerant, and the frequency of the inverter pump. [Figure 6] 11 is a diagram showing changes in the flow rate of the refrigerant and the power consumption of the inverter pump and the first constant speed pump when the frequency of the inverter pump is changed. FIG. [Figure 7] 11 is a diagram showing changes in refrigerant pressure in the inverter pump and the first constant speed pump, and changes in power consumption of the inverter pump and the first constant speed pump when the frequency of the inverter pump is changed. FIG. [Figure 8] 4 is a flowchart showing an example of a processing procedure performed by a control device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. (Pump System 1) FIG. 1 is a diagram showing a schematic configuration of a pump system 1 to which this embodiment is applied. The pump system 1 includes a refrigerant circuit 2 through which a refrigerant circulates. The pump system 1 also includes a pump unit 3 that is connected to the refrigerant circuit 2 and sends out refrigerant to the refrigerant circuit 2 to circulate the refrigerant through the refrigerant circuit 2. The pump system 1 also includes a condenser 4 that releases heat of the refrigerant circulating through the refrigerant circuit 2 to the outside and condenses the refrigerant. The pump system 1 also includes an evaporator 5 that absorbs heat from the outside and evaporates the refrigerant circulating through the refrigerant circuit 2. The pump system 1 also includes a control device 10 that controls the operation of the pump unit 3. The pump system 1 is used, for example, in an evaporator 5, to absorb heat from a heat source by means of a refrigerant circulating in a refrigerant circuit 2, thereby cooling the heat source.

[0010] The refrigerant circuit 2 has a space formed therein through which the refrigerant flows, and is generally formed of annular piping. The refrigerant circulating through the refrigerant circuit 2 is not particularly limited, but examples thereof include R32, R454C, propane, R1234yf, R1234ze, ammonia, water, and the like.

[0011] The pump unit 3 is connected to the refrigerant circuit 2 and includes an inverter-equipped pump 31 that can change the flow rate of refrigerant discharged per unit time by inverter control. The pump unit 3 is also connected to the refrigerant circuit 2 and includes a first constant speed pump 32 and a second constant speed pump 33 that discharge a constant flow rate of refrigerant per unit time. The inverter-equipped pump 31, the first constant speed pump 32, and the second constant speed pump 33 are connected in parallel to the refrigerant circuit 2. In addition, in the pump system 1, the piping constituting the refrigerant circuit 2 branches into three pipes upstream of the pump unit 3. Each of the branched pipes is connected to the upstream side of the inverter-equipped pump 31, the first constant speed pump 32, and the second constant speed pump 33, respectively. In addition, the three pipes connected to the downstream side of the inverter-equipped pump 31, the first constant speed pump 32, and the second constant speed pump 33, respectively, merge into one pipe downstream of the pump unit 3.

[0012] The inverter-equipped pump 31 has a motor 311 that draws in refrigerant from a pipe connected to the upstream side and discharges it to a pipe connected to the downstream side, thereby circulating the refrigerant in the refrigerant circuit 2. The inverter-equipped pump 31 also has an inverter 312 that drives the motor 311 to rotate at a predetermined frequency. The inverter-equipped pump 31 also has a switch 313 that switches the rotation of the motor 311 on and off. The inverter pump 31 is capable of changing the flow rate of the refrigerant discharged per unit time to the refrigerant circuit 2 depending on the frequency at which the inverter 312 rotates the motor 311 .

[0013] The first constant speed pump 32 has a motor 321 that draws in refrigerant from a pipe connected to the upstream side and discharges it to a pipe connected to the downstream side, thereby circulating the refrigerant in the refrigerant circuit 2. The first constant speed pump 32 also has a switch 323 that switches the rotation of the motor 321 on and off. Similarly, the second constant speed pump 33 has a motor 331 that discharges the refrigerant drawn from a pipe connected to the upstream side to a pipe connected to the downstream side, and circulates the refrigerant in the refrigerant circuit 2. The second constant speed pump 33 also has a switch 333 that switches the rotation of the motor 331 on and off.

[0014] (Control device 10) Next, the configuration of the control device 10 will be described. The control device 10 has a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory). The ROM stores a control program executed by the CPU. The CPU reads out the control program stored in the ROM and executes the control program using the RAM as a working area. The control program executed by the CPU may be provided in a state stored in a computer-readable recording medium such as a magnetic recording medium (such as a magnetic tape or a magnetic disk), an optical recording medium (such as an optical disk), a magneto-optical recording medium, a semiconductor memory, etc. Also, it may be downloaded using a communication means such as the Internet.

[0015] FIG. 2 is a block diagram showing an example of a functional configuration of the control device 10 to which the present embodiment is applied. The control device 10 of this embodiment includes an acquisition unit 110 that acquires the frequency at which the inverter-equipped pump 31 operates and the power consumption of the inverter-equipped pump 31. The control device 10 also includes a determination unit 120 that determines whether the inverter-equipped pump 31 is in a shut-off operation state based on the frequency at which the inverter-equipped pump 31 operates and the power consumption of the inverter-equipped pump 31. The control device 10 also includes a storage unit 130 that stores various information. The control device 10 also includes an operation control unit 140 that controls the operation of the pump unit 3. In this embodiment, the determination unit 120 and the operation control unit 140 are an example of a control unit that controls the operations of the inverter-equipped pump 31, the first constant speed pump 32, and the second constant speed pump 33 based on the relationship between the power consumption of the inverter-equipped pump 31 and the shut-off power consumption.

[0016] The acquisition unit 110 acquires the frequency at which the inverter-equipped pump 31 operates, more specifically, the frequency at which the inverter 312 of the inverter-equipped pump 31 rotates and drives the motor 311. Hereinafter, the frequency at which the inverter-equipped pump 31 operates may be referred to as the frequency of the inverter-equipped pump 31. Furthermore, the acquiring unit 110 acquires the power consumption consumed by the inverter-equipped pump 31. Hereinafter, the power consumption consumed by the inverter-equipped pump 31 may be referred to as the power consumption of the inverter-equipped pump 31.

[0017] The acquisition unit 110 acquires the frequency and power consumption of the inverter-equipped pump 31 when the inverter-equipped pump 31 is used in combination with at least one of the first constant speed pump 32 and the second constant speed pump 33 to circulate refrigerant through the refrigerant circuit 2 in the pump system 1. The acquiring unit 110 may acquire the frequency and power consumption of the inverter-equipped pump 31 from the pump unit 3 by monitoring the operation of the inverter-equipped pump 31. The acquiring unit 110 may also acquire the frequency and power consumption of the inverter-equipped pump 31 from an operation control unit 140 that controls the operation of the inverter-equipped pump 31.

[0018] The determination unit 120 determines whether or not the inverter-equipped pump 31 is in a shut-off operation state based on the frequency and power consumption of the inverter-equipped pump 31 acquired by the acquisition unit 110. The shut-off operation state refers to a state in which the inverter-equipped pump 31 is operating and consuming power, but no refrigerant is discharged from the inverter-equipped pump 31. In a pump system 1 having a refrigerant circuit 2 in which the inverter-equipped pump 31 and constant-speed pumps (first constant-speed pump 32, second constant-speed pump 33) are connected in parallel, if the frequency of the inverter-equipped pump 31 is excessively lowered, the refrigerant discharge pressure by the inverter-equipped pump 31 may become significantly lower than that of the constant-speed pump. In this case, the shut-off operation state is entered in which the inverter-equipped pump 31 does not discharge refrigerant, and the power consumption required for the operation of the inverter-equipped pump 31 may be wasted.

[0019] The determination unit 120 determines whether the inverter-equipped pump 31 is in a shut-off operation state based on the relationship between the power consumption of the inverter-equipped pump 31 acquired by the acquisition unit 110 and the shut-off power consumption of the inverter-equipped pump 31. More specifically, the determination unit 120 determines that the inverter-equipped pump 31 is in a shut-off operation state when the power consumption of the inverter-equipped pump 31 is equal to the shut-off power consumption of the inverter-equipped pump 31. Here, in this embodiment, the power consumption of the inverter pump 31 being equal to the shut-off power consumption does not necessarily mean that the power consumption of the inverter pump 31 and the shut-off power consumption are completely the same. For example, when the difference between the power consumption of the inverter pump 31 and the shut-off power consumption is equal to or less than a predetermined threshold, the determination unit 120 can determine that the power consumption of the inverter pump 31 is equal to the shut-off power consumption. The threshold can be determined arbitrarily depending on the performance of the inverter pump 31, etc.

[0020] The shut-off power consumption of the inverter-equipped pump 31 is the power consumed by the inverter-equipped pump when the inverter-equipped pump 31 is operated with the discharge port of the inverter-equipped pump 31, from which the refrigerant is discharged by the motor 311, closed. Although details will be described later, the shut-off power consumption of the inverter-equipped pump 31 differs depending on the frequency of the inverter-equipped pump 31. In the control device 10 of this embodiment, the memory unit 130 stores the shut-off power consumption of the inverter-equipped pump 31 in association with the frequency of the inverter-equipped pump 31. The determination unit 120 obtains from the memory unit 130 the shut-off power consumption corresponding to the frequency of the inverter-equipped pump 31 obtained by the acquisition unit 110, and determines whether the inverter-equipped pump 31 is in a shut-off operating state by comparing the power consumption of the inverter-equipped pump 31 obtained by the acquisition unit 110 with the shut-off power consumption.

[0021] The following describes the relationship between the power consumed by the inverter pump 31, the flow rate of the refrigerant discharged from the inverter pump 31, and the frequency of the inverter pump 31. Here, the frequency of the inverter pump 31 was changed and the power consumed by the inverter pump 31 and the flow rate of the refrigerant discharged from the inverter pump 31 were measured. FIG. 3 is a diagram showing a schematic configuration of a pump system 80 used in the measurement.

[0022] In a pump system 80 shown in Fig. 3, three pumps 81, 82, and 83 that circulate a refrigerant through a refrigerant circuit 89 are connected in parallel. In the pump system 80, a valve 85 is connected in parallel to the three pumps 81, 82, and 83. In the pump system 80, a valve 86 is provided in a pipe connected to the downstream side of the pumps 81, 82, and 83 and the valve 85. In this example, the valve 85 is in a fully closed state, and no refrigerant flows through the pipe of the refrigerant circuit 89 to which the valve 85 is connected. In addition, the valve 86 is in a fully open state. In the pump system 80, the pumps 81, 82, and 83 each have a valve 91, 92, and 93 that opens and closes a discharge port of the refrigerant.

[0023] First, in a pump system 80 to which an inverter-equipped pump 31 (see FIG. 1) is connected, the relationship between the power consumed by the inverter-equipped pump 31, the flow rate of the refrigerant discharged from the inverter-equipped pump 31, and the frequency of the inverter-equipped pump 31 will be described. In the pump system 80 shown in FIG. 3, the pump 81 is the inverter-equipped pump 31 that can change the flow rate of the refrigerant discharged per unit time by inverter control.

[0024] Then, the frequency of the inverter-equipped pump 31 was changed by the inverter 312 (see FIG. 1) between 30 Hz and 50 Hz in increments of 1 Hz, and the power consumed by the inverter-equipped pump 31 was measured. The power consumed by the inverter-equipped pump 31 was measured both when the valve 91 was fully open and when the valve 91 was fully closed. Here, the power consumed by the inverter-equipped pump 31 when the valve 91 was fully open is the above-mentioned power consumption of the inverter-equipped pump 31. Moreover, the power consumed by the inverter-equipped pump 31 when the valve 91 was fully closed, i.e., when the inverter-equipped pump 31 was in a shut-off operating state, is the above-mentioned shut-off power consumption of the inverter-equipped pump 31. Moreover, when the valve 91 was fully opened, the flow rate of the refrigerant flowing through the pipes connected to the downstream side of the pumps 81, 82, and 83 and the valve 85 in the refrigerant circuit 89 was measured. In this example, valves 92 and 93 are fully closed for pumps 82 and 83. In this case, refrigerant does not flow through the pipes to which pumps 82 and 83 are connected. In addition, in this example, refrigerant is circulated in refrigerant circuit 89 by pump 81 (inverter-equipped pump 31).

[0025] Fig. 4 is a graph showing the relationship between the power consumption of the inverter pump 31, the shutoff power consumption of the inverter pump 31, and the flow rate of the refrigerant, and the frequency of the inverter pump 31. In Fig. 4, the horizontal axis represents the frequency of the inverter pump 31, and the vertical axis represents the power consumed by the inverter pump 31 and the flow rate of the refrigerant. 4, in a pump system 80 connected to an inverter pump 31, the flow rate of refrigerant circulating through a refrigerant circuit 89 increases as the frequency of the inverter pump 31 increases. Also, in a pump system 80 connected to an inverter pump 31, the power consumption of the inverter pump 31 increases as the frequency of the inverter pump 31 increases. Furthermore, in a pump system 80 to which the inverter-equipped pump 31 is connected, even if the inverter-equipped pump 31 is in a shut-off operation state, the shut-off power consumption of the inverter-equipped pump 31 is not zero. Also, in a pump system 80 to which the inverter-equipped pump 31 is connected, the shut-off power consumption of the inverter-equipped pump 31 increases as the frequency of the inverter-equipped pump 31 increases.

[0026] Next, a description will be given of the relationship between the power consumed by the inverter-equipped pump 31 and the frequency of the inverter-equipped pump 31 in a pump system 80 in which the inverter-equipped pump 31 (see FIG. 1) and a constant-speed pump are connected in parallel. In pump system 80 shown in Fig. 3, pump 81 is first constant speed pump 32 (see Fig. 1) in which the flow rate of refrigerant discharged per unit time is constant. Also, in pump system 80, pump 82 is inverter-equipped pump 31 in which the flow rate of refrigerant discharged per unit time can be changed by inverter control. In this example, valves 91 and 92 are fully open.

[0027] Then, the frequency of inverter-equipped pump 31 was changed in 1 Hz increments between 30 Hz and 50 Hz by inverter 312 (see FIG. 1), and the power consumption of first constant-speed pump 32 and inverter-equipped pump 31, and the flow rate of refrigerant flowing through the piping connected to the downstream side of pumps 81, 82, 83 and valve 85 in refrigerant circuit 89 were measured. In this example, the valve 93 for the pump 83 is fully closed. In this case, the refrigerant does not flow through the piping to which the pump 83 is connected. In addition, in this example, the refrigerant is circulated in the refrigerant circuit 89 by the pump 81 (first constant speed pump 32) and the pump 82 (inverter-equipped pump 31) connected in parallel.

[0028] Fig. 5 is a graph showing the relationship between the power consumption of the inverter-equipped pump 31 and the first constant speed pump 32, the flow rate of the refrigerant, and the frequency of the inverter-equipped pump 31. In Fig. 5, the horizontal axis shows the frequency of the inverter-equipped pump 31, and the vertical axis shows the power consumed by the inverter-equipped pump 31 or the first constant speed pump 32, and the flow rate of the refrigerant. Fig. 5 also shows the shut-off power consumption of the inverter-equipped pump 31 shown in Fig. 4. As shown in Figure 5, in a pump system 80 in which an inverter-equipped pump 31 and a first constant speed pump 32 are connected in parallel, as in Figure 4, the power consumption of the inverter-equipped pump 31 increases as the frequency of the inverter-equipped pump 31 increases. In the pump system 80 in which the inverter-equipped pump 31 and the first constant-speed pump 32 are connected in parallel, the power consumption of the first constant-speed pump 32 is approximately constant regardless of the frequency of the inverter-equipped pump 31 .

[0029] 5, when the frequency of the inverter pump 31 is lower than 32 Hz, the power consumption of the inverter pump 31 is approximately equal to the shut-off power consumption. In addition, it has been confirmed that in the pump system 80 in which the inverter pump 31 and the first constant speed pump 32 are connected in parallel, when the frequency of the inverter pump 31 is lower than a predetermined value, the power consumption of the inverter pump 31 is equal to the shut-off power consumption. As described above, the shut-off power consumption of the inverter-equipped pump 31 is the power consumed by the inverter-equipped pump 31 when the discharge port of the inverter-equipped pump 31 is closed, i.e., when no refrigerant is discharged from the inverter-equipped pump 31. For this reason, in the pump system 80 in which the inverter-equipped pump 31 and the first constant speed pump 32 are connected in parallel, when the power consumption of the inverter-equipped pump 31 and the shut-off power consumption are equal, it can be considered that no refrigerant is discharged from the inverter-equipped pump 31.

[0030] From the above relationship, when the power consumption of the inverter pump 31 is equal to the shut-off power consumption of the inverter pump 31, the determination unit 120 determines that the inverter pump 31 is in the shut-off operation state.

[0031] Incidentally, in the pump system 1, it is possible to detect that the inverter-equipped pump 31 is in a shutoff operation state by using a flow meter that measures the flow rate of the refrigerant discharged from the inverter-equipped pump 31. However, since it is costly to install a flow meter for the inverter-equipped pump 31, the pump system 1 tends to be expensive. In particular, when a flow meter is installed for each of the inverter-equipped pump 31, the first constant speed pump 32, and the second constant speed pump 33 that constitute the pump system 1, the cost tends to be high. In contrast, in the pump system 1 of this embodiment, it is possible to detect that the inverter-equipped pump 31 is in a shut-off operation state without using a flow meter to measure the flow rate of refrigerant discharged from the inverter-equipped pump 31.

[0032] Returning to FIG. 2, the storage unit 130 stores the shutoff power consumption of the inverter-equipped pump 31 (see FIG. 1) in association with the frequency of the inverter-equipped pump 31. The shutoff power consumption for each frequency of the inverter-equipped pump 31 can be calculated by the following formula (1). Cut-off power consumption = {reference power consumption x (frequency / f) 3} / Inverter efficiency…(1) Here, the reference power consumption means the power consumed when the pump is operated from a commercial power source with the discharge port fully closed. The reference power consumption is a value specific to each inverter-equipped pump 31 and is determined according to the performance of the inverter-equipped pump 31, etc. f is the frequency of the AC current supplied by the commercial power source. In eastern Japan, the frequency of the commercial power source is 50 Hz, so f is 50. In western Japan, the frequency of the commercial power source is 60 Hz, so f is 60.

[0033] The operation control unit 140 controls the operations of the inverter-equipped pump 31, the first constant speed pump 32, and the second constant speed pump 33 (all see FIG. 1 ) based on the determination result by the determination unit 120. In addition, when the determination unit 120 determines that the inverter-equipped pump 31 is in a shut-off operation state, the operation control unit 140 controls the operations of the inverter-equipped pump 31, the first constant speed pump 32, and the second constant speed pump 33 so as to reduce the total power consumption of the inverter-equipped pump 31, the first constant speed pump 32, and the second constant speed pump 33.

[0034] For example, when the determination unit 120 determines that the inverter-equipped pump 31 is in a shut-off operation state, the operation control unit 140 turns off any one of the switches 313, 323, or 333 (see FIG. 1 for all). In other words, the operation control unit 140 stops the operation of any one of the inverter-equipped pump 31, the first constant speed pump 32, or the second constant speed pump 33. This reduces the number of pumps that are operating among the inverter-equipped pump 31, the first constant speed pump 32, and the second constant speed pump 33, thereby reducing the power consumption of the pump system 1.

[0035] Next, we will explain the behavior of the refrigerant in the refrigerant circuit 89 when the frequency of the inverter pump 31 is changed or the operation of the inverter pump 31 is stopped in a pump system 80 in which an inverter pump 31 and a constant speed pump are connected in parallel. In the pump system 80 shown in Fig. 3, the pump 81 is the first constant speed pump 32, and the pump 82 is the inverter pump 31. In this example, the valves 91 and 92 are fully open. As for the pump 83, the valve 93 is fully closed. In this case, the refrigerant does not flow through the pipe to which the pump 83 is connected. In addition, in this example, the refrigerant is circulated in the refrigerant circuit 89 by the pump 81 (first constant speed pump 32) and the pump 82 (the inverter pump 31) connected in parallel.

[0036] 6 is a diagram showing changes in the flow rate of the refrigerant and the power consumption of the inverter pump 31 and the first constant speed pump 32 when the frequency of the inverter pump 31 is changed. In Fig. 6, the horizontal axis represents time, and the vertical axis represents the flow rate of the refrigerant, the frequency of the inverter pump 31, and the power consumption of the inverter pump 31 and the first constant speed pump 32. In this example, the flow rate of the refrigerant refers to the flow rate of the refrigerant flowing through the pipes connected to the downstream side of the pumps 81 , 82 , 83 and the valve 85 in the refrigerant circuit 89 .

[0037] 7 is a diagram showing changes in the pressure of the refrigerant in the refrigerant circuit 2 and the power consumption of the inverter pump 31 and the first constant speed pump 32 when the frequency of the inverter pump 31 is changed. In Fig. 7, the horizontal axis represents time, and the vertical axis represents the pressure of the refrigerant, the frequency of the inverter pump 31, and the power consumption of the inverter pump 31 and the first constant speed pump 32. In this example, the upstream refrigerant pressure is the pressure of the refrigerant flowing through a pipe connected to the upstream side of the pump unit 3 in the refrigerant circuit 2. The downstream refrigerant pressure is the pressure of the refrigerant flowing through a pipe connected to the downstream side of the pump unit 3 in the refrigerant circuit 2.

[0038] 6 and 7, the frequency of the inverter pump 31 is changed to 30 Hz at time T1. As described above, the inverter pump 31 has the same power consumption and shut-off power consumption when the frequency is lower than 32 Hz. Therefore, in the example shown in Fig. 6 and 7, the inverter pump 31 is in a shut-off operation state at time T1. 6 and 7, after time T1, the frequency of the inverter pump 31 was reduced from 30 Hz to 20 Hz by 1 Hz at predetermined time intervals. Then, at time T2, the switch 313 of the inverter pump 31 was switched to the OFF state, and the operation of the inverter pump 31 was stopped. During this time, the first constant speed pump 32 continued to operate with the switch 323 in the ON state.

[0039] As shown in Figures 6 and 7, even when the frequency of the inverter-equipped pump 31 in the shut-off operation state was changed, and even when the operation of the inverter-equipped pump 31 was stopped, there was no change in the power consumption of the first constant-speed pump 32. Furthermore, as shown in FIG. 6, even when the frequency of the inverter-equipped pump 31 in the shutoff operation state was changed, and even when the operation of the inverter-equipped pump 31 was stopped, the flow rate of the refrigerant circulating through the refrigerant circuit 89 did not change. Furthermore, as shown in FIG. 7, even when the frequency of the inverter-equipped pump 31 in the shutoff operation state was changed, and even when the operation of the inverter-equipped pump 31 was stopped, there was no change in the discharge pressure of the refrigerant in the entire pump system 1.

[0040] From the above, it has been confirmed that by stopping the operation of the inverter pump 31 when the inverter pump 31 is in a shut-off operation state, it is possible to reduce the power consumption required for the operation of the inverter pump 31 without affecting the operation of the first constant speed pump 32 or the behavior of the refrigerant in the refrigerant circuit 89.

[0041] In addition, when it is determined that the inverter-equipped pump 31 is in a shut-off operation state, the operation control unit 140 may stop the operation of the inverter-equipped pump 31, or may stop the operation of the first constant speed pump 32 or the second constant speed pump 33. In the pump system 1, from the viewpoint of making it possible to adjust the flow rate of the refrigerant circulating through the refrigerant circuit 2, it is preferable that the operation control unit 140 stops the operation of the first constant speed pump 32 or the second constant speed pump 33 when it is determined that the inverter-equipped pump 31 is in a shut-off operation state.

[0042] For example, when the determination unit 120 determines that the inverter-equipped pump 31 is in a shut-off operation state, the operation control unit 140 turns off one of the switch 323 or the switch 333 to stop the operation of the first constant speed pump 32 or the second constant speed pump 33. As a result, in the pump system 1, the number of operating pumps among the inverter-equipped pump 31, the first constant speed pump 32, and the second constant speed pump 33 is reduced, so that the power consumption of the pump system 1 can be reduced. Additionally, the operation control unit 140 also controls to increase the frequency of the inverter pump 31 in order to maintain the flow rate of the refrigerant circulating through the refrigerant circuit 2. As a result, the inverter pump 31 is no longer in a shutoff operation state, and the refrigerant begins to be discharged from the inverter pump 31 to the refrigerant circuit 2. This prevents the power consumption required for the operation of the inverter pump 31 from being wasted.

[0043] Next, the process performed by the control device 10 of this embodiment will be described. FIG. 8 is a flowchart showing an example of the procedure of the process performed by the control device 10. As shown in FIG. In the pump system 1, when the inverter-equipped pump 31 and at least one of the first constant speed pump 32 and the second constant speed pump 33 are operating simultaneously, the control device 10 performs the processing shown in FIG. 8 at predetermined time intervals.

[0044] In the control device 10, the acquisition unit 110 acquires the frequency of the inverter-equipped pump 31 and the power consumption of the inverter-equipped pump 31 from the pump unit 3 (step 101). Next, the control device 10 causes the determination unit 120 to obtain from the storage unit 130 the cut-off power consumption corresponding to the frequency of the inverter-equipped pump 31 obtained in step 101 (step 102). Next, the control device 10 causes the determination unit 120 to compare the power consumption of the inverter-equipped pump 31 acquired in step 101 with the shut-off power consumption of the inverter-equipped pump 31 acquired in step 102 (step 103).

[0045] If the power consumption of the inverter-equipped pump 31 is not equal to the shut-off power consumption of the inverter-equipped pump 31 (NO in step 103), the control device 10 returns to step 101 and continues the process. On the other hand, if the power consumption of the inverter pump 31 is equal to the shut-off power consumption of the inverter pump 31 (YES in step 103), the determination unit 120 determines that the inverter pump 31 is in the shut-off operation state (step 104).

[0046] Next, the control device 10 changes the operating conditions of the inverter-equipped pump 31, the first constant speed pump 32, and the second constant speed pump 33 so that the operation control unit 140 reduces the total power consumption of the inverter-equipped pump 31, the first constant speed pump 32, and the second constant speed pump 33 (step 105). For example, the operation control unit 140 stops the operation of any of the inverter-equipped pump 31, the first constant speed pump 32, and the second constant speed pump 33. This reduces the total power consumption of the inverter-equipped pump 31, the first constant speed pump 32, and the second constant speed pump 33. With the above, the control device 10 ends the series of processes.

[0047] As described above, the pump system 1 of the present embodiment includes the refrigerant circuit 2 through which the refrigerant circulates. The pump system 1 also includes the inverter-equipped pump 31 that is connected to the refrigerant circuit 2 and is capable of changing the flow rate of the refrigerant discharged to the refrigerant circuit 2 by inverter control. The pump system 1 also includes the first constant speed pump 32 and the second constant speed pump 33 that are connected to the refrigerant circuit 2 in parallel with the inverter-equipped pump 31 and discharge a constant flow rate of the refrigerant to the refrigerant circuit 2. The pump system 1 also includes a control device 10 that acquires the frequency and power consumption of the inverter-equipped pump 31 and controls the operations of the inverter-equipped pump 31, the first constant speed pump 32, and the second constant speed pump 33 based on the relationship between the power consumption of the inverter-equipped pump 31 and the shutoff power consumption. As a result, the pump system 1 can reduce the power required to operate the inverter pump 31, the first constant speed pump 32 and the second constant speed pump 33 without using a flow meter to measure the flow rate of refrigerant discharged from the inverter pump 31.

[0048] The control device 10 of the present embodiment also includes an acquisition unit 110 that acquires the frequency and power consumption of the inverter-equipped pump 31 in the refrigerant circuit 2 in which the inverter-equipped pump 31, the first constant speed pump 32, and the second constant speed pump 33 are connected in parallel. The control device 10 also includes an operation control unit 140 that controls the operations of the inverter-equipped pump 31, the first constant speed pump 32, and the second constant speed pump 33 based on the relationship between the power consumption of the inverter-equipped pump 31 and the shut-off power consumption. As a result, the control device 10 can reduce the power required to operate the inverter pump 31, the first constant speed pump 32 and the second constant speed pump 33 without using a flow meter to measure the flow rate of the refrigerant discharged from the inverter pump 31.

[0049] Although the embodiments of the present invention have been described above, the technical scope of the present invention is not limited to the scope described in the above-mentioned embodiments. In the above-described pump system 1, one inverter-equipped pump 31 and two constant-speed pumps (first constant-speed pump 32, second constant-speed pump 33) are connected in parallel in the refrigerant circuit 2. However, as long as the inverter-equipped pump 31 and the constant-speed pumps are connected in parallel in the refrigerant circuit 2, the number of the inverter-equipped pumps 31 and the constant-speed pumps is not limited to this. For example, a plurality of inverter-equipped pumps 31 may be connected in parallel in the refrigerant circuit 2. In this case, the control device 10 compares the power consumption of each inverter-equipped pump 31 with the shut-off power consumption, and determines whether each inverter-equipped pump 31 is in the shut-off operation state. Then, when it is determined that any of the inverter-equipped pumps 31 is in the shut-off operation state, the control device 10 controls the operation of the inverter-equipped pump 31 and the constant-speed pump by the operation control unit 140 so as to reduce the power consumption.

[0050] In addition, in the present embodiment, the pump system 1 is used to cool the heat source in the evaporator 5, but the present invention is not limited to this. The pump system 1 may be used in any manner as long as it circulates the refrigerant in the refrigerant circuit 2 by the inverter-equipped pump 31 and the constant speed pump connected in parallel. [Explanation of symbols]

[0051] Reference Signs List 1... pump system, 2... refrigerant circuit, 3... pump section, 4... condenser, 5... evaporator, 10... control device, 31... inverter-equipped pump, 32... first constant speed pump, 33... second constant speed pump, 110... acquisition section, 120... determination section, 130... storage section, 140... operation control section, 311, 321, 331... motor, 312... inverter, 313, 323, 333... switch

Claims

1. an acquisition unit that acquires an operating frequency of an inverter-equipped pump and power consumption of the inverter-equipped pump in a refrigerant circuit in which an inverter-equipped pump capable of changing a flow rate of a discharged refrigerant by inverter control and a constant-speed pump whose flow rate of a discharged refrigerant is constant are connected in parallel; a control unit that controls operations of the inverter-equipped pump and the constant-speed pump based on a relationship between the power consumption of the inverter-equipped pump and a shut-off power consumption that the inverter-equipped pump consumes when the pump is operated at the frequency with a discharge port closed; Equipped with When the power consumption of the inverter pump is equal to the shutoff power consumption when the inverter pump is operated at the frequency, the control unit determines that the inverter pump is not discharging refrigerant, and controls the operation of the inverter pump and the constant speed pump so as to reduce the sum of the power consumed by the inverter pump and the constant speed pump. Control device.

2. 2. The control device according to claim 1, wherein the cut-off power consumption when the inverter-equipped pump is operated at the frequency is calculated from a standard power consumption consumed by the inverter-equipped pump when the amount of refrigerant discharged by the inverter-equipped pump is zero, the frequency, and an inverter efficiency of the inverter-equipped pump.

3. The refrigerant circuit is connected to a plurality of the constant speed pumps, 2. The control device according to claim 1, wherein the control unit reduces the number of the constant speed pumps discharging the refrigerant when the power consumption of the inverter-equipped pump is equal to the shut-off power consumption when the inverter-equipped pump is operated at the frequency.

4. a refrigerant circuit in which a refrigerant circulates; an inverter-equipped pump connected to the refrigerant circuit and capable of changing a flow rate of the refrigerant discharged into the refrigerant circuit by inverter control; a constant speed pump connected to the refrigerant circuit in parallel with the inverter pump and discharging a constant flow rate of refrigerant into the refrigerant circuit; a control device that acquires a frequency at which the inverter-equipped pump operates and power consumption by the inverter-equipped pump, and controls operations of the inverter-equipped pump and the constant-speed pump based on a relationship between the power consumption and a shut-off power consumption that the inverter-equipped pump consumes when the pump operates at the frequency with a discharge port closed; Equipped with When the power consumption of the inverter pump is equal to the shutoff power consumption when the inverter pump is operated at the frequency, the control device determines that the refrigerant is not being discharged from the inverter pump, and controls the operation of the inverter pump and the constant speed pump so as to reduce the sum of the power consumed by the inverter pump and the constant speed pump. Pump system.

5. On the computer, A function of acquiring the frequency at which an inverter-equipped pump operates and the power consumption of the inverter-equipped pump in a refrigerant circuit in which an inverter-equipped pump capable of changing the flow rate of the refrigerant discharged by inverter control and a constant-speed pump whose flow rate of the refrigerant discharged is constant are connected in parallel; a function of determining that refrigerant is not being discharged from the inverter-equipped pump when the power consumption of the inverter-equipped pump is equal to the cut-off power consumption when the inverter-equipped pump is operated at the frequency based on a relationship between the power consumption of the inverter-equipped pump and a cut-off power consumption consumed by the inverter-equipped pump when the inverter-equipped pump is operated at the frequency with a discharge port closed, and controlling the operation of the inverter-equipped pump and the constant-speed pump so as to reduce a sum of the power consumed by the inverter-equipped pump and the constant-speed pump; A program to achieve this.

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