WO2018016028A1

WO2018016028A1 - Refrigeration cycle device

Info

Publication number: WO2018016028A1
Application number: PCT/JP2016/071273
Authority: WO
Inventors: 和幸塚本
Original assignee: 三菱電機株式会社
Priority date: 2016-07-20
Filing date: 2016-07-20
Publication date: 2018-01-25

Abstract

In a refrigeration cycle device relating to the present invention, a refrigerant circuit for circulating a refrigerant is configured by connecting, by piping, a plurality of compressors, a condenser, a decompression device, and an evaporator, said compressors being connected in parallel to each other by piping. The refrigeration cycle device is provided with: inverter devices that drive the compressors at a rotation number corresponding to a drive frequency relating to alternating current conversion; and a control device that controls the inverter devices such that the compressors start at one time or within a predetermined time.

Description

Refrigeration cycle equipment

This invention relates to a refrigeration cycle apparatus. In particular, the present invention relates to a refrigeration cycle apparatus having a plurality of compressors.

For example, there are refrigeration cycle devices such as a refrigerator and a chiller unit, in which a refrigerant circuit is configured by sequentially connecting at least a compressor, a condenser, an expansion valve, and an evaporator. And in order to supply a big capability, there exists a refrigerating-cycle apparatus comprised by piping connecting a some compressor in parallel.

In general, in a refrigeration cycle apparatus equipped with a plurality of compressors driven at a constant speed, when supplying electric power by starting a compressor, first, after starting the first compressor, A starting method called “sequential start” is a method in which the next compressor is started after a certain time (generally 10 seconds or more) has elapsed, and the next compressor is started after a certain time (typically 10 seconds or more). It is known (for example, refer to Patent Document 1).

At this time, for example, each compressor is driven by a star delta start system. The star delta start method is a start method that can reduce the starting current to 1/3 of the start method called direct-input start by performing star start that starts with a star connection for a predetermined time at start. . In starting, the time until the starting current decreases is called the starting time.

駆動 The drive time for star connection is generally set longer than the start time. When the compressor is driven by the star connection for a set time, the compressor is switched to the delta connection, and the steady drive by the delta connection is performed. At the time of sequential start, after the previous compressor is switched to steady drive with delta connection, star start of the next compressor is started.

JP 2000-257964 A

In a refrigeration cycle apparatus that performs “sequential start” that is generally used, it takes a long time for all of the plurality of compressors to start and to reach full load operation corresponding to 100% load. For this reason, for example, when the refrigeration load increases rapidly and a large refrigeration capacity is required in a short time, the follow-up to the refrigeration load is delayed.

Here, in order to cope with a sudden load fluctuation, it is conceivable to simultaneously start a plurality of compressors driven at a constant speed. However, even if it can be said that the starting current can be reduced by star starting, a starting current of about 2 to 3 times the rated current flowing during steady driving is instantaneously generated. In addition, when switching from star connection to delta connection, an instantaneous large current called an inrush current (about 2 to 10 times the rated current) is generated. In order to cope with these currents, the electric capacity of the power supply equipment and the size of the power supply line must be increased, resulting in an increase in equipment cost.

The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a refrigeration cycle apparatus that suppresses a starting current and has high followability to a refrigeration load.

In the refrigeration cycle apparatus according to the present invention, a plurality of compressors, a condenser, a decompression device, and an evaporator are connected by piping to constitute a refrigerant circuit in which refrigerant is circulated, and the plurality of compressors are connected by piping in parallel. And an inverter device that drives the plurality of compressors at a rotation speed corresponding to a drive frequency related to AC conversion, and a control device that controls the inverter device so as to start the plurality of compressors simultaneously or within a predetermined time. Is.

According to the present invention, a plurality of compressors whose rotational speeds are controlled by the inverter device are connected in parallel, and the control device starts the plurality of compressors simultaneously or within a predetermined time. The refrigeration capacity following the load can be supplied in a shorter time than in the past. In addition, since the inverter device controls the drive frequency, the starting current that flows when starting the compressor can be made smaller than the current in the star delta start, so the electric capacity of the power supply equipment and the size of the power supply line Can be made smaller than before, and the cost can be reduced.

It is a figure which shows the structure of the refrigerating-cycle apparatus which concerns on Embodiment 1 of this invention. It is a figure explaining the operation | movement at the time of start-up of the refrigerator 100 which concerns on Embodiment 1 of this invention. It is the figure which showed the outline of the relationship between the electric current including the time of starting, and time in the compressor 11 which concerns on Embodiment 1 of this invention. In the refrigerator 100 which concerns on Embodiment 1 of this invention, it is the figure which showed the outline of the relationship between the refrigerating capacity including the time of starting, and time. It is a figure explaining the operation | movement at the time of start-up of the refrigerator 100 which concerns on Embodiment 2 of this invention. It is the figure which showed the outline of the relationship between the electric current including the time of a start in the compressor 11 which concerns on Embodiment 2 of this invention, the pressure of the low voltage | pressure side of a refrigerant circuit, and time.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Here, in the following drawings, what attached | subjected the same code | symbol is the same or it corresponds, and shall be common in the whole sentence of embodiment described below. Moreover, the form of the component shown by the whole specification is an illustration to the last, and is not limited to these description. In particular, the combination of the constituent elements is not limited to the combination in each embodiment, and the constituent elements described in the other embodiments can be applied to other embodiments as appropriate. The pressure level is not particularly determined in relation to the absolute value, but is relatively determined in terms of the state and operation of the system and apparatus. In addition, when there is no need to distinguish or identify a plurality of similar devices that are distinguished by subscripts, the subscripts may be omitted.

Embodiment 1 FIG.
1 is a diagram showing a configuration of a refrigeration cycle apparatus according to Embodiment 1 of the present invention. Hereinafter, the refrigerator 100 will be described as a representative example of the refrigeration cycle apparatus. The refrigerator 100 has a refrigerant circuit configured by connecting a plurality of compressors 11, a condenser 12, a decompressor 13, and an evaporator 14 through refrigerant piping. The refrigerator 100 according to the first embodiment circulates the refrigerant filled in the refrigerant circuit, cools the air in the cooling target space, and performs refrigeration, freezing, and the like of the objects stored in the cooling target space.

For example, a non-azeotropic mixed refrigerant, a pseudo-azeotropic mixed refrigerant, a single refrigerant, or the like may be used as the refrigerant circulating in the refrigerant circuit. Non-azeotropic refrigerant mixture includes, for example, R407C (R32 / R125 / R134a) which is an HFC (hydrofluorocarbon) refrigerant. Examples of the pseudoazeotropic refrigerant mixture include R410A (R32 / R125) and R404A (R125 / R143a / R134a), which are HFC refrigerants. Examples of the single refrigerant include R22, which is an HCFC (hydrochlorofluorocarbon) refrigerant, and R134a, which is an HFC refrigerant.

The compressor 11 sucks the refrigerant, compresses it, and discharges it in a high temperature / high pressure state. The compressor 11 according to the first embodiment is configured by a compressor of a type that can adjust the refrigerant capacity by controlling the rotation speed while keeping the torque constant in accordance with the drive frequency of the inverter device 19. The refrigerator 100 according to Embodiment 1 has a configuration in which four compressors 11A to 11D are connected in parallel in a refrigerant circuit. The inverter device 19 has a switching element, for example, and performs DC-AC conversion to supply power to the compressor 11. At this time, the number of rotations of the compressor 11 can be arbitrarily changed according to the drive frequency at the time of conversion. In the first embodiment, the inverter devices 19A to 19D supply power to the compressors 11A to 11D, respectively. Here, the compression method of the compressor 11 is not particularly limited. For example, any of a reciprocating type, a rotary type, and a speed type may be sufficient. Further, the plurality of compressors 11 need not all be the same compression method.

The condenser 12 exchanges heat between air outside the space to be cooled and the compressed refrigerant from the compressor 11 and air, for example, to condense and liquefy the refrigerant. Here, the condenser 12 is used to condense the refrigerant, but a heat radiator may be used instead of the condenser to radiate heat to the refrigerant.

The decompression device 13 decompresses and expands the refrigerant. For example, a flow rate control means such as an electronic expansion valve, a refrigerant flow rate adjustment means such as an expansion valve having a temperature sensing cylinder, and the like are used. The evaporator 14 performs heat exchange between the refrigerant whose pressure is reduced by the decompression device 13 and the air in the space to be cooled, evaporates and vaporizes the refrigerant, and cools the air.

Also, the condensing fan 15 allows air outside the space to be cooled to pass through the condenser 12, for example. Moreover, the evaporation side fan 16 passes the air of cooling object space through the evaporator 14, for example, and sends it out to cooling object space again.

The control device 20 is a device composed of, for example, a microcomputer having a CPU (Central Processing Unit). The control device 20 controls equipment that constitutes the refrigerator 100. Here, although it demonstrates as the refrigerator 100 having the control apparatus 20, you may install outside the refrigerator 100, for example. In the first embodiment, the control device 20 controls the drive frequency of the inverter device 19 particularly when the plurality of compressors 11 are started. Then, the starting current relating to the plurality of compressors 11 is suppressed.

Next, the operation of each component device of the refrigerator 100 will be described based on the flow of the refrigerant circulating in the refrigerant circuit. The compressor 11 sucks the refrigerant, compresses it, and discharges it in a high temperature / high pressure state. The discharged refrigerant flows into the condenser 12. The condenser 12 exchanges heat between the air outside the cooling target space supplied by the condensation side fan 15 and the refrigerant, and condenses and liquefies the refrigerant. The condensed and liquefied refrigerant passes through the decompression device 13. The decompression device 13 decompresses the refrigerant that has condensed and passed therethrough. The decompressed refrigerant flows into the evaporator 14. The evaporator 14 exchanges heat between the air in the space to be cooled supplied by the evaporation side fan 16 and the refrigerant to evaporate the refrigerant. Then, the compressor 11 sucks the evaporated gas refrigerant.

FIG. 2 is a diagram for explaining the operation at the start of the refrigerator 100 according to Embodiment 1 of the present invention. When operating the refrigerator 100, the control device 20 outputs a compressor operation command to each inverter device 19 (step S1). Each inverter device 19 adjusts the drive frequency based on the compressor operation command, and drives the compressor 11 at, for example, the minimum number of revolutions at which refrigerant can be sucked and discharged (step S2). By outputting the compressor operation command to each inverter device 19 at the same time, all the compressors 11 related to the driving start at the same time, or all the compressors 11 can be regarded as being driven at the same time. Within (for example, within 10 seconds).

The control device 20 increases the drive frequency of each inverter device 19 and increases the rotation speed of each compressor 11 (step S3). Here, in Embodiment 1, the control apparatus 20 controls the drive frequency in each inverter apparatus 19 so that the rotation speed of each compressor 11 may become the same. By making the rotational speed the same and the capacity the same, it can be expected that the distribution of the refrigerant and the refrigerating machine oil is less likely to be biased.

And the control apparatus 20 judges whether the drive frequency of each inverter apparatus 19 became a predetermined rated frequency (step S4). The rated frequency is a driving frequency corresponding to the rotational speed in steady driving in which the compressor 11 is driven stably. When it is determined that the drive frequency of each inverter device 19 has reached the rated frequency, load follow-up frequency control for changing the drive frequency of each inverter device 19 corresponding to the refrigeration load and supplying the refrigeration capacity according to the refrigeration load is performed. (Step S5).

FIG. 3 is a diagram showing an outline of the relationship between current and time including start-up in the compressor 11 according to Embodiment 1 of the present invention. FIG. 3 (a) shows the relationship between current and time including start-up in the first embodiment. FIG.3 (b) shows the relationship between the electric current including the time of starting in the conventional refrigerator, and time for a comparison. FIG. 3 shows the current supplied to one compressor 11 and the current supplied to four compressors. Basically, the current supplied to the four compressors 11 is obtained by superimposing four currents in the single compressor 11.

As shown in FIG. 3, immediately after the compressor 11 is started, the current value temporarily increases. However, since the control device 20 controls the drive frequency of the inverter device 19 to drive the compressor 11 at the lowest rotation speed, the starting current is smaller than the current in steady driving. And if the rotation speed of the compressor 11 goes up and the compressor 11 becomes a steady drive, an electric current will be stabilized. The drive current in the compressor 11 after the stable state changes depending on the operating conditions of the refrigerator 100 by the refrigeration load. From the above, the capacity of the power supply equipment, the size of the power supply line, etc. may be selected based on the current when the compressor 11 is driven at the rotational speed in the steady drive.

FIG. 4 is a diagram showing an outline of the relationship between the refrigeration capacity including the start-up and time in the refrigerator 100 according to Embodiment 1 of the present invention. In FIG. 4, the relationship between the refrigerating capacity and time including the starting time in the conventional refrigerator is also shown for comparison. Each of the plurality of compressors 11 mounted on the refrigerator 100 gradually increases in operating frequency from the start at the same timing. As the driving frequency increases, the amount of refrigerant gas sucked and discharged by the compressor 11 increases. Since the amount of refrigerant circulating in the refrigerant circuit increases, the refrigeration capacity increases.

As described above, according to the refrigerator 100 of the first embodiment, since the plurality of compressors 11 having the inverter device 19 are connected in parallel, the plurality of compressors 11 can be driven at the same time. The refrigeration capacity corresponding to the load can be supplied quickly. In particular, the effect increases as the cooling capacity to be supplied increases. For this reason, for example, air in a living room for air conditioning applications, meat and fish in a refrigerated warehouse for refrigeration applications, and vegetables, fresh flowers, etc. in a refrigerator for refrigeration applications can be quickly moved to a desired temperature. Can be reached. Thereby, it can contribute to provision of comfortable space, food with high freshness, and the like.

At this time, by adjusting the driving frequency of the inverter device 19 at the time of starting, for example, the compressor 11 can be driven at the minimum number of revolutions, so that the starting current in the compressor 11 is made higher than the current in steady driving. It can be kept small. For this reason, the electric capacity of the power supply facility and the size of the power supply line can be selected based on the current in steady driving, and the cost can be suppressed.

Embodiment 2. FIG.
In the first embodiment described above, all the compressors 11 are started within a predetermined time (for example, 10 seconds) that can be regarded as simultaneous or equivalent. However, if all the compressors 11 are started simultaneously or within, for example, 10 seconds, the opening degree of the decompression device 13 cannot be adjusted in time, and a follow-up delay may occur. If the follow-up of the decompression device 13 is delayed, the refrigerant pressure on the low pressure side of the refrigerant circuit may drop, and may stop due to a low pressure drop abnormality.

Therefore, in the second embodiment, the drive frequency of the inverter device 19 is adjusted based on the detection by the low pressure side pressure detection device 21 so that the pressure on the low pressure side of the refrigerant circuit does not become lower than the set pressure. It is.

FIG. 5 is a diagram for explaining the operation at the start of the refrigerator 100 according to the second embodiment of the present invention. The equipment configuration of the refrigerator 100 in the second embodiment is the same as that in the first embodiment. When operating the refrigerator 100, the control device 20 outputs a compressor operation command to each inverter device 19 (step S11). Each inverter device 19 adjusts the drive frequency based on the compressor operation command, and drives the compressor 11 at the minimum rotational speed (step S12).

Then, the control device 20 determines whether or not the low pressure is higher than the set pressure (step S13). If it is determined that the low pressure is not higher than the set pressure (the low pressure is equal to or lower than the set pressure), the drive frequency of each inverter device 19 is maintained (step S14).

On the other hand, if it is determined that the low pressure is higher than the set pressure, the drive frequency of each inverter device 19 is increased to increase the rotation speed of each compressor 11 (step S15). And the control apparatus 20 judges whether the drive frequency of each inverter apparatus 19 became a predetermined rated frequency (step S16). When it is determined that the drive frequency of each inverter device 19 has reached the rated frequency, load follow-up frequency control for changing the drive frequency of each inverter device 19 corresponding to the refrigeration load and supplying the refrigeration capacity according to the refrigeration load is performed. (Step S17).

FIG. 6 is a diagram showing an outline of the relationship between the current, including the starting time, the pressure on the low pressure side of the refrigerant circuit, and time in the compressor 11 according to Embodiment 2 of the present invention. As shown in FIG. 6, when the pressure on the low pressure side of the refrigerant circuit is equal to or lower than the set pressure, the driving frequency in the inverter device 19 is maintained to prevent the low pressure side pressure from decreasing.

As described above, according to the refrigerator 100 of the second embodiment, when the control device 20 has the low-pressure side pressure of the refrigerant circuit related to detection by the low-pressure side pressure detection device 21 equal to or lower than the set pressure, the inverter device 19. Since the drive frequency at is maintained, low pressure drop abnormality can be prevented. For this reason, the abnormal stop at the time of starting can be avoided, and the refrigerating capacity according to the refrigerating load can be quickly supplied.

Embodiment 3 FIG.
In the first embodiment and the second embodiment described above, the inverter device 19 is installed corresponding to each compressor 11, but the present invention is not limited to this. For example, each compressor 11 may be driven by one inverter device 19.

In the first and second embodiments described above, the application to the refrigerator 100 has been described. The present invention is not limited to these devices, and can also be applied to other refrigeration cycle devices that constitute a refrigerant circuit and perform cooling, air conditioning, and the like, such as an air conditioner and a water heater.

11, 11A, 11B, 11C, 11D compressor, 12 condenser, 13 decompression device, 14 evaporator, 15 condensation side fan, 16 evaporation side fan, 19, 19A, 19B, 19C, 19D inverter device, 20 control device, 21 Low pressure side pressure detector, 100 refrigerator.

Claims

A refrigerant circuit in which a plurality of compressors, condensers, pressure reducing devices and evaporators are connected by piping to circulate the refrigerant is configured.
Multiple compressors are connected in parallel by piping,
An inverter device that drives the plurality of compressors at a rotational speed corresponding to a driving frequency related to AC conversion;
A refrigeration cycle apparatus comprising: a control device that controls the inverter device so as to start a plurality of the compressors simultaneously or within a predetermined time.
A pressure detecting device for detecting a pressure on a low pressure side of the refrigerant circuit;
2. The refrigeration cycle apparatus according to claim 1, wherein when the control device determines that the low-pressure side pressure related to detection by the pressure detection device is equal to or lower than a set pressure, the control device does not increase the drive frequency of the inverter device. .
The refrigeration cycle apparatus according to claim 1 or 2, wherein the control device controls the inverter device so as to start a plurality of the compressors at a minimum number of rotations.