Cooling system of water chilling unit

Abstract

The invention relates to a cooling system of a water chilling unit. The system comprises a main loop and a cooling branch. The main loop comprises a compressor, a condenser and an evaporator; the compressor, the condenser and the evaporator are sequentially communicated end to end to form a loop; the cooling branch comprises a first branch, and a first expansion valve is arranged on the first branch; an inlet of the first branch is communicated with an outlet of the condenser, and an outlet of the first branch is communicated with an inlet of the evaporator; and the first branch passes through the motor of the compressor and is used for cooling the motor of the compressor. The working temperature of the motor of the compressor can be reduced, and then the refrigerating or heating effect of the water chilling unit is improved. And on the other hand, the refrigerant flow can be adjusted in real time according to the motor temperature of the compressor, and the cooling efficiency is improved. In addition, the first branch can share the refrigerant, the evaporator, the condenser and other equipment with the main loop, and the branch setting cost is low.

Description

Technical Field

[0001] This application relates to the field of chiller technology, and in particular to a cooling system for a chiller. Background Technology

[0002] Chillers, as key equipment in modern air conditioning and industrial refrigeration systems, play a crucial role in maintaining suitable temperatures, improving comfort, and enhancing production efficiency, and are widely used in various fields. Typically, chillers provide cooling for air conditioning and industrial equipment by supplying chilled water. Furthermore, with certain configurations and additional equipment, chillers can also provide heating functions.

[0003] However, during the operation of a chiller unit, the high operating temperature of the compressor motor may reduce the chiller unit's cooling or heating capacity. When the compressor is running, the compressor motor windings generate heat. In cases where the compressor has a compact structure and operates at high speed, the motor's heat dissipation environment is poor, leading to high compressor motor temperatures that can affect the normal operation of the chiller unit.

[0004] In traditional technologies, there is currently no effective solution to the problem of reduced cooling or heating performance of chillers due to the high operating temperature of the compressor motor. Summary of the Invention

[0005] Therefore, it is necessary to provide a cooling system for a chiller unit that can cool the motor of the compressor, thereby improving the cooling or heating effect of the chiller unit, in order to address the above-mentioned technical problems.

[0006] In a first aspect, this application provides a cooling system for a chiller unit, the system including a main circuit and cooling branch circuits; the main circuit includes a compressor, a condenser and an evaporator; the compressor, condenser and evaporator are connected end to end in sequence to form a circuit;

[0007] The cooling branch includes a first branch, on which a first expansion valve is provided;

[0008] The inlet of the first branch is connected to the outlet of the condenser, and the outlet of the first branch is connected to the inlet of the evaporator; the first branch passes through the motor of the compressor and is used to cool the motor of the compressor.

[0009] In one embodiment, the system further includes a first temperature control device, and the compressor is equipped with a first temperature detection device. The first temperature control device is connected to both the first temperature detection device and the first expansion valve.

[0010] The first temperature detection device is used to detect the motor temperature and send the data to the first temperature control device;

[0011] The first temperature control device is used to control the opening degree of the first expansion valve according to the motor temperature.

[0012] In one embodiment, the first temperature control device is also connected to the compressor, and controlling the opening degree of the first expansion valve according to the motor temperature includes:

[0013] If the motor temperature is less than or equal to the first threshold, then the first expansion valve is controlled to close.

[0014] If the motor temperature is greater than the first threshold and less than the second threshold, the opening degree of the first expansion valve is controlled according to the first preset rule, wherein the second threshold is greater than the first threshold.

[0015] If the motor temperature is greater than or equal to the second threshold, the compressor is controlled to stop.

[0016] In one embodiment, controlling the opening degree of the first expansion valve according to a first preset rule includes:

[0017] If the motor temperature is less than or equal to the third threshold, then the first expansion valve is controlled to decrease from its current opening until the motor temperature is greater than the third threshold, wherein the third threshold is greater than the first threshold and less than the second threshold;

[0018] If the motor temperature is greater than or equal to the fourth threshold, the first expansion valve is controlled to increase from its current opening until the motor temperature is less than the fourth threshold, wherein the fourth threshold is greater than the third threshold and less than the second threshold.

[0019] In one embodiment, controlling the opening degree of the first expansion valve according to the first preset rule further includes:

[0020] A first opening degree matching the motor temperature is determined according to a first preset relationship, wherein the first preset relationship includes a preset linear relationship between the motor temperature and the first expansion valve opening degree;

[0021] The opening degree of the first expansion valve is controlled according to the first opening degree.

[0022] In one embodiment, the main circuit includes a frequency converter connected to the compressor;

[0023] The cooling branch also includes a second branch, on which a second expansion valve is provided;

[0024] The inlet of the second branch is connected to the outlet of the condenser, and the outlet of the second branch is connected to the inlet of the evaporator; the second branch is arranged in parallel with the first branch; the second branch passes through the frequency converter and is used to cool the frequency converter.

[0025] In one embodiment, the system further includes a second temperature control device, and the frequency converter is equipped with a second temperature detection device. The second temperature control device is connected to both the second temperature detection device and the second expansion valve.

[0026] The second temperature detection device is used to detect the inverter temperature and send the data to the second temperature control device;

[0027] The second temperature control device is used to control the opening degree of the second expansion valve according to the temperature of the frequency converter.

[0028] In one embodiment, the second temperature control device is also connected to the frequency converter, and controlling the opening degree of the second expansion valve according to the temperature of the frequency converter includes:

[0029] If the inverter temperature is less than or equal to the fifth threshold, then the second expansion valve is controlled to close.

[0030] If the inverter temperature is greater than the fifth threshold and less than the sixth threshold, the opening of the second expansion valve is controlled according to the second preset rule, wherein the sixth threshold is greater than the fifth threshold.

[0031] If the inverter temperature is greater than or equal to the sixth threshold, the compressor is controlled to stop.

[0032] In one embodiment, controlling the opening degree of the second expansion valve according to a second preset rule includes:

[0033] If the inverter temperature is less than or equal to the seventh threshold, the second expansion valve is controlled to decrease from its current opening until the inverter temperature is greater than the seventh threshold, which is greater than the fifth threshold and less than the sixth threshold.

[0034] If the inverter temperature is greater than or equal to the eighth threshold, the second expansion valve is controlled to increase from its current opening until the inverter temperature is less than the eighth threshold, which is greater than the seventh threshold and less than the sixth threshold.

[0035] In one embodiment, controlling the opening degree of the second expansion valve according to the second preset rule further includes:

[0036] A second opening degree matching the inverter temperature is determined according to a second preset relationship, wherein the second preset relationship includes a preset linear relationship between the inverter temperature and the second expansion valve opening degree;

[0037] The opening degree of the second expansion valve is controlled according to the second opening degree.

[0038] In one embodiment, the main circuit includes a frequency converter, a compressor, a condenser, and an evaporator; the compressor, condenser, and evaporator are connected end-to-end in sequence to form a circuit; the frequency converter is connected to the compressor.

[0039] The cooling branch includes a third branch, a fourth branch, and a fifth branch, and a third expansion valve is provided on the third branch;

[0040] The inlet of the third expansion valve is connected to the outlet of the condenser;

[0041] The inlet of the fourth branch is connected to the outlet of the third expansion valve, and the outlet of the fourth branch is connected to the inlet of the evaporator; the fourth branch passes through the motor of the compressor and is used to cool the motor of the compressor.

[0042] The inlet of the fifth branch is connected to the outlet of the third expansion valve, and the outlet of the fifth branch is connected to the inlet of the evaporator; the fifth branch passes through the frequency converter and is used to cool the frequency converter.

[0043] The cooling system of the aforementioned chiller unit includes a main circuit and cooling branch circuits. The main circuit includes a compressor, a condenser, and an evaporator. The compressor, condenser, and evaporator are connected end-to-end to form a circuit. The cooling branch circuit includes a first branch circuit, on which a first expansion valve is installed. The inlet of the first branch circuit is connected to the outlet of the condenser, and the outlet of the first branch circuit is connected to the inlet of the evaporator. The first branch circuit passes through the motor of the compressor, thereby cooling the compressor motor. By setting a first branch circuit connected to the condenser and evaporator, and passing through the compressor motor, the compressor motor can be cooled, reducing its operating temperature and thus improving the chiller unit's cooling or heating effect. Furthermore, by installing a first expansion valve on the first branch circuit, the refrigerant flow rate in the first branch circuit can be adjusted, thereby adjusting the refrigerant flow rate in real time according to the compressor motor temperature, improving cooling efficiency. In addition, the first branch circuit of this application can share refrigerant and equipment such as the evaporator and condenser with the main circuit, resulting in lower branch circuit setup costs.

[0044] Details of one or more embodiments of this application are set forth in the following drawings and description to make other features, objects and advantages of this application more readily apparent. Attached Figure Description

[0045] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0046] Figure 1 This is a schematic diagram of the cooling system structure of a chiller unit in one embodiment;

[0047] Figure 2 This is a schematic diagram of the cooling system structure of a chiller unit that cools the compressor motor in one embodiment;

[0048] Figure 3 This is a schematic diagram of the motor temperature control process in one embodiment;

[0049] Figure 4 This is a schematic diagram of the cooling system structure of a chiller unit that cools the compressor motor and the frequency converter in one embodiment;

[0050] Figure 5 This is a schematic diagram of the inverter temperature control process in one embodiment.

[0051] Figure Descriptions: 101, Compressor; 102, Condenser; 103, Evaporator; 104, First Expansion Valve; 105, First Temperature Detection Device; 106, Dryer; 107, Economizer; 108, First Working Expansion Valve; 109, Second Working Expansion Valve; 110, First Branch; 201, Inverter; 202, Compressor; 203, Condenser; 204, Evaporator; 205, First Temperature Detection Device; 206, Second Temperature Detection Device; 207, Second Expansion Valve; 208, First Expansion Valve; 209, Dryer; 210, Economizer; 211, First Working Expansion Valve; 212, Second Working Expansion Valve; 213, Second Branch. Detailed Implementation

[0052] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0053] The terms “module”, “unit”, etc., used below refer to a combination of software and / or hardware that can perform a predetermined function. Although the apparatus described in the following embodiments is preferably implemented in hardware, implementation in software, or a combination of software and hardware, is also possible and contemplated.

[0054] In the embodiments of this application, such as Figure 1As shown, a cooling system for a chiller unit is provided. The system includes a main circuit and cooling branches. The main circuit includes a compressor, a condenser, and an evaporator. The compressor, condenser, and evaporator are connected end-to-end in sequence to form a circuit. The cooling branches include a first branch with a first expansion valve installed on it. The inlet of the first branch is connected to the outlet of the condenser, and the outlet of the first branch is connected to the inlet of the evaporator. The first branch passes through the motor of the compressor and is used to cool the motor of the compressor.

[0055] In this embodiment, the chiller unit includes a unit for providing chilled water to achieve air conditioning and industrial equipment cooling functions. Furthermore, the chiller unit may also include a unit for achieving heating functions. The chiller unit may include air-suspended centrifugal chiller units, magnetic levitation centrifugal chiller units, etc. Especially for air-suspended centrifugal chiller units, their compressors have a compact structure and operate at high speeds, resulting in a harsh heat dissipation environment for the compressor motor. This leads to problems such as increased temperature causing reduced motor efficiency and lifespan, thus requiring a more effective cooling method. The cooling system of the chiller unit provided in this embodiment is used to cool the compressor motor in the chiller unit.

[0056] The cooling system of the chiller unit includes a main circuit and cooling branch circuits. The main circuit includes a compressor 101, a condenser 102, and an evaporator 103; the compressor 101, condenser 102, and evaporator 103 are connected end-to-end to form a circuit; the cooling branch circuit includes a first branch circuit 110, on which a first expansion valve 104 is installed; the inlet of the first branch circuit 110 is connected to the outlet of the condenser 102, and the outlet of the first branch circuit 110 is connected to the inlet of the evaporator 103; the first branch circuit 110 passes through the motor of the compressor 101 and is used to cool the motor of the compressor 101.

[0057] In this embodiment, compressor 101 is used to compress refrigerant, thereby increasing the temperature and pressure of the refrigerant and providing power for the condensation and evaporation processes. Specifically, compressor 101 draws in low-pressure, low-temperature refrigerant from the outlet of evaporator 103, compresses it into high-pressure, high-temperature gaseous refrigerant, and discharges it into condenser 102. Compressor 101 may include a reciprocating compressor, centrifugal compressor, screw compressor, etc. A motor is installed in compressor 101. As a key component driving the operation of compressor 101, the motor operates at a relatively high temperature during operation based on electromagnetic induction and the basic operating mechanism of an electric motor; therefore, cooling of the motor in compressor 101 is necessary.

[0058] In other embodiments, such as Figure 2As shown, the main circuit also includes a dryer 106, an economizer 107, a first working expansion valve 108, and a second working expansion valve 109. The inlet of the dryer 106 is connected to the outlet of the condenser 102. The outlet of the dryer 106 is connected to both the inlet of the first branch 110 and the inlet of the first working expansion valve 108. The outlet of the first working expansion valve 108 is connected to the inlet of the economizer 107. The first outlet of the economizer 107 is connected to the first inlet of the second expansion valve 107, and the second outlet of the economizer 107 is connected to the second inlet of the compressor 101. The outlet of the second working expansion valve 109 is connected to both the outlet of the first branch 110 and the inlet of the evaporator 103. The outlet of the evaporator 103 is connected to the first inlet of the compressor 101. The first outlet of the compressor 101 is connected to the inlet of the condenser 102. The third outlet of the compressor 101 is also connected to the second inlet of the compressor 101.

[0059] In this embodiment, the dryer 106 is used to remove moisture and impurities from the refrigerant, protecting the stable operation of the chiller unit. The economizer 107 may include a flash tank for recooling the refrigerant. After throttling, the refrigerant enters the economizer 107 and undergoes gas-liquid separation. The gas phase enters the second inlet of the compressor 101, where it merges with the gas after primary compression for secondary compression. The economizer 107 introduces a portion of the high-temperature, high-pressure gaseous refrigerant for pre-cooling, resulting in a lower temperature when the refrigerant enters the evaporator 103, thereby improving evaporation efficiency and reducing the load on the compressor 101. The first working expansion valve 108 and the second working expansion valve 109 function similarly to the first expansion valve 104 in the first branch 110, used to regulate and control the refrigerant flow rate in the chiller unit's working circuit and reduce the refrigerant pressure in the working circuit. The third outlet of the compressor 101, connected to the second inlet of the compressor 101, performs secondary compression of the refrigerant to improve its cooling effect.

[0060] In this embodiment, the first branch 110 may include a piping device with refrigerant flowing inside. The inlet of the first branch 110 is connected to the outlet of the condenser 102 in the main circuit, and the outlet of the first branch 110 is connected to the inlet of the evaporator 103 in the main circuit. The condenser 102 is used to condense the high-temperature, high-pressure gaseous refrigerant into a high-pressure liquid refrigerant. The evaporator 103 is used to evaporate the low-pressure liquid refrigerant into a low-pressure gaseous refrigerant.

[0061] The first branch 110 passes through the motor of the compressor 101 and is used to cool the motor of the compressor 101. By diverting the refrigerant flowing from the condenser 102 or the dryer 106, the first branch 110 achieves cooling of the compressor motor at a lower cost with minor modifications to the original chiller unit structure, thereby improving the operating efficiency of the chiller unit.

[0062] Specifically, the condenser absorbs heat released by the refrigerant through heat exchange with the cooling medium (usually air or water), causing it to condense into a liquid state. The liquid refrigerant enters the first branch from the condenser outlet and passes through the first expansion valve located on this branch. The first expansion valve is used to adjust the flow rate of the liquid refrigerant and to reduce the refrigerant pressure, converting the high-pressure liquid refrigerant into a low-pressure liquid refrigerant or a low-pressure gas-liquid mixture. The first expansion valve can include an electronic expansion valve, a thermostatic expansion valve, etc. Understandably, the greater the refrigerant flow rate through the compressor motor in the first branch, the better the cooling effect on the compressor motor; conversely, the smaller the refrigerant flow rate through the compressor motor in the first branch, the worse the cooling effect on the compressor motor.

[0063] The first expansion valve on the first branch can control the cooling effect on the compressor motor by adjusting the refrigerant flow through it. Low-pressure refrigerant passes through the compressor motor in the main circuit within the first branch. After absorbing heat from the compressor motor and cooling it, the refrigerant enters the evaporator through the evaporator inlet. The evaporator evaporates the low-pressure liquid refrigerant into a low-pressure gaseous refrigerant. Normally, during normal operation of the main circuit, the evaporator exchanges heat with the chilled water, causing the liquid refrigerant to evaporate and lower the chilled water temperature, thereby providing chilled water to the external target equipment of the chiller unit for cooling.

[0064] The cooling system of the aforementioned chiller unit includes a main circuit and a first branch circuit. The main circuit includes a compressor, a condenser, and an evaporator. The compressor, condenser, and evaporator are sequentially connected end-to-end to form a circuit. The cooling branch circuit includes a first branch circuit, on which a first expansion valve is installed. The inlet of the first branch circuit is connected to the outlet of the condenser, and the outlet of the first branch circuit is connected to the inlet of the evaporator. The first branch circuit passes through the motor of the compressor, thereby cooling the compressor motor. By setting a first branch circuit connected to the condenser and evaporator, and passing through the compressor motor, the compressor motor can be cooled, reducing its operating temperature and thus improving the cooling or heating effect of the chiller unit. On the other hand, by setting a first expansion valve on the first branch circuit, the refrigerant flow rate in the first branch circuit can be adjusted, thereby adjusting the refrigerant flow rate in real time according to the motor temperature of the compressor, improving cooling efficiency. Furthermore, the first branch circuit of this application can share refrigerant and equipment such as the evaporator and condenser with the main circuit, resulting in lower branch circuit setup costs.

[0065] In some embodiments, the system further includes a first temperature control device. A first temperature detection device 105 is provided on the compressor 101. The first temperature control device is connected to the first temperature detection device 105 and the first expansion valve 104 respectively. The first temperature detection device 105 is used to detect the motor temperature and send it to the first temperature control device. The first temperature control device is used to control the opening degree of the first expansion valve 104 according to the motor temperature.

[0066] In this embodiment, to achieve more accurate control of the motor temperature of the compressor 101, a first temperature detection device 105 can be installed on the compressor 101. The first temperature detection device 105 is used to detect the motor temperature of the compressor 101 and may include devices such as an infrared thermometer, a temperature sensor, and a thermistor. The system also includes a first temperature control device, which is connected to both the first temperature detection device 105 and the first expansion valve 104. After acquiring the motor temperature, the first temperature control device can control the opening degree of the first expansion valve 104 based on the motor temperature, thereby controlling the refrigerant flow rate through the motor in the first branch 110, thus achieving precise control of the motor temperature. It should be noted that in this embodiment, "connection" refers to electrical connection between devices, and "connection" refers to connection between pipeline devices.

[0067] The following describes the method for controlling the motor temperature through embodiments of this application. In some embodiments, the first temperature control device is also connected to the compressor, and controlling the opening degree of the first expansion valve according to the motor temperature includes:

[0068] S201: If the motor temperature is less than or equal to the first threshold, then control the first expansion valve to close.

[0069] S203: If the motor temperature is greater than the first threshold and less than the second threshold, then the opening degree of the first expansion valve is controlled according to the first preset rule, wherein the second threshold is greater than the first threshold.

[0070] S205: If the motor temperature is greater than or equal to the second threshold, then control the compressor to stop.

[0071] In this embodiment, if the motor temperature is less than or equal to the first threshold T1, it indicates that the motor temperature is low and no cooling is required. The first temperature control device can control the first expansion valve to close, that is, control the opening degree of the first expansion valve to 0, so that the refrigerant flow through the compressor motor is 0, and stop the cooling of the compressor motor.

[0072] If the motor temperature is greater than the first threshold T1 and less than the second threshold T2, the opening degree of the first expansion valve is controlled according to the first preset rule, where the second threshold T2 is greater than the first threshold T1. The first preset rule may include a preset relationship between the motor temperature and the opening degree of the first expansion valve; it may also include a preset stepped opening control method, such as a certain motor temperature range corresponding to a certain opening degree.

[0073] If the motor temperature is greater than or equal to the second threshold T2, it indicates that the compressor motor temperature is too high and the compressor motor needs to be stopped immediately. The first temperature control device controls the compressor to stop.

[0074] This application sets different temperature thresholds T1 and T2, and controls the opening of the expansion valve or the compressor to stop according to different motor temperatures. This can effectively cool the motor, thereby improving the working efficiency of the chiller unit and extending the service life of the motor.

[0075] The following embodiments illustrate two methods for controlling the opening degree of the first expansion valve according to a first preset rule.

[0076] In some embodiments, controlling the opening degree of the first expansion valve according to a first preset rule includes:

[0077] S301: If the motor temperature is less than or equal to the third threshold, then control the first expansion valve to decrease from its current opening until the motor temperature is greater than the third threshold, wherein the third threshold is greater than the first threshold and less than the second threshold.

[0078] S303: If the motor temperature is greater than or equal to the fourth threshold, then control the first expansion valve to increase from its current opening degree until the motor temperature is less than the fourth threshold, wherein the fourth threshold is greater than the third threshold and less than the second threshold.

[0079] In this embodiment, if the motor temperature is controlled between a third threshold T3 and a fourth threshold T4, the motor's operating efficiency is high. Therefore, if the motor temperature is less than or equal to the third threshold T3 and greater than the first threshold T1, the first expansion valve is controlled to decrease its opening, reducing the refrigerant flow through the motor and causing the motor temperature to rise until it exceeds the third threshold T3, where the third threshold T3 is greater than the first threshold T1 and less than the second threshold T2. On the other hand, if the motor temperature is greater than or equal to the fourth threshold T4 and less than the second threshold T2, the first expansion valve is controlled to increase its opening, increasing the refrigerant flow through the motor and causing the motor temperature to decrease until it falls below the fourth threshold T4, where the fourth threshold T4 is greater than the third threshold T3 and less than the second threshold T2.

[0080] In this embodiment, by adjusting the opening of the first expansion valve using a first temperature control device, the motor temperature can be controlled between the third threshold T3 and the fourth threshold T4, which can effectively improve the motor's operating efficiency while preventing the motor temperature from becoming too high.

[0081] In other embodiments, controlling the opening degree of the first expansion valve according to the first preset rule further includes:

[0082] S401: Determine a first opening degree that matches the motor temperature according to a first preset relationship, wherein the first preset relationship includes a preset linear relationship between the motor temperature and the opening degree of the first expansion valve.

[0083] S403: Control the opening degree of the first expansion valve according to the first opening degree.

[0084] In this embodiment, the first preset relationship may further include a preset linear relationship between motor temperature and the opening degree of the first expansion valve. In some specific embodiments, if the preset motor temperature range includes a first threshold T1 to a second threshold T2, and the first opening degree of the first expansion valve is 0 to 100%, then the first opening degree corresponding to the motor temperature being the first threshold T1 can be 0, and the first opening degree corresponding to the motor temperature being the second threshold T2 can be 100%. Therefore, the motor temperature between the first threshold T1 and the second threshold T2 can have a linear correspondence with the first opening degree of the first expansion valve between 0 and 100%. In other embodiments, the first opening degree of the first expansion valve within the range of 0 to 100% can also have a linear relationship with the motor temperature within other temperature threshold ranges. This application does not limit the specific method for determining the preset linear relationship and can set it according to the actual application scenario.

[0085] In this embodiment, by using a linear relationship, a matching first opening degree can be determined based on the motor temperature, and then the opening degree of the first expansion valve can be controlled based on the first opening degree, which can improve the control efficiency of motor temperature and control the motor temperature more accurately.

[0086] The following example, using an air-suspension compressor, illustrates the method for controlling motor temperature through a specific embodiment. Figure 3As shown, the first temperature detection device acquires the motor temperature T of the air-suspension compressor and sends it to the first temperature control device. If the motor temperature T is less than or equal to the first threshold T1, the first temperature control device controls the first expansion valve to close, i.e., shuts down the motor cooling system. If the motor temperature T is greater than T1 and less than T2, the first temperature control device controls the first expansion valve to open, i.e., turns on the motor cooling system. Specifically, if the motor temperature T is less than or equal to the third threshold T3, the opening of the first expansion valve is reduced until the motor temperature is greater than the third threshold T3; if the motor temperature T is greater than or equal to the fourth threshold T4, the opening of the first expansion valve is increased until the motor temperature T is less than the fourth threshold T4, thereby maintaining the motor temperature between T3 and T4. If the motor temperature is greater than or equal to the second threshold T2, the first temperature control device controls the compressor to shut down.

[0087] The following describes a method for controlling the cooling of a frequency converter when the main circuit includes a frequency converter, using embodiments of this application.

[0088] In some embodiments, the main circuit includes a frequency converter 201 connected to the compressor 202; the cooling branch further includes a second branch 213, on which a second expansion valve 207 is provided; the inlet of the second branch 213 is connected to the outlet of the condenser 203, and the outlet of the second branch 213 is connected to the inlet of the evaporator 204; the second branch 213 is arranged in parallel with the first branch 110; the second branch 213 passes through the frequency converter 201 and is used to cool the frequency converter 201.

[0089] In this embodiment, the frequency converter 201 is electrically connected to the compressor 202 and is used to control the compressor motor. Specifically, the frequency converter 201 achieves precise control of the motor speed by changing the power supply frequency. In some embodiments, the cooling system of the chiller unit may only have the second branch 213 as a cooling branch for cooling the frequency converter; or only the first branch 110 may be provided for cooling the compressor; or both the first and second branches may be provided simultaneously for cooling the compressor and the frequency converter respectively.

[0090] In other embodiments, such as Figure 4 As shown, the cooling branch includes both a first branch and a second branch, and the first branch and the second branch are connected in parallel. Regarding... Figure 4 The equipment in the working circuit of the chiller unit shown, such as compressor 202, condenser 203, evaporator 204, first temperature detection device 205, first expansion valve 208, dryer 209, economizer 210, first working expansion valve 211, and second working expansion valve 212, can refer to the functions of the corresponding equipment in the above motor cooling embodiment, and will not be repeated here.

[0091] In this embodiment, the cooling branch includes a second branch 213, which passes through the frequency converter 201 and is used to cool the frequency converter 201. The second branch 213 diverts the refrigerant flowing from the condenser 203 or the dryer 209, achieving cooling of the frequency converter at a lower cost with minimal modifications to the original chiller unit structure, thereby improving the operating efficiency of the chiller unit.

[0092] In some embodiments, the system further includes a second temperature control device. A second temperature detection device 206 is provided on the frequency converter 201. The second temperature control device is connected to the second temperature detection device 206 and the second expansion valve 207 respectively. The second temperature detection device 206 is used to detect the frequency converter temperature and send it to the second temperature control device. The second temperature control device is used to control the opening degree of the second expansion valve 207 according to the frequency converter temperature.

[0093] In this embodiment, to achieve more accurate temperature control of the inverter 201, a second temperature detection device 206 can be installed on the inverter 201. The second temperature detection device 206 is used to detect the inverter temperature and may include devices such as an infrared thermometer, a temperature sensor, and a thermistor. A second temperature control device is also provided in the system, connected to both the second temperature detection device 206 and the second expansion valve 207. After acquiring the inverter temperature, the second temperature control device can control the opening degree of the second expansion valve 207 based on the inverter temperature, thereby controlling the refrigerant flow rate through the inverter in the second branch 213, thus achieving precise temperature control of the inverter.

[0094] The following describes the method for controlling the inverter temperature through embodiments of this application. In some embodiments, the second temperature control device is also connected to the inverter, and controlling the opening degree of the second expansion valve according to the inverter temperature includes:

[0095] S501: If the inverter temperature is less than or equal to the fifth threshold, then control the second expansion valve to close.

[0096] S503: If the inverter temperature is greater than the fifth threshold and less than the sixth threshold, the opening degree of the second expansion valve is controlled according to the second preset rule, wherein the sixth threshold is greater than the fifth threshold.

[0097] S505: If the inverter temperature is greater than or equal to the sixth threshold, then control the compressor to stop.

[0098] In this embodiment, if the inverter temperature is less than or equal to the fifth threshold T5, it indicates that the inverter temperature is low and cooling is unnecessary. The second temperature control device can control the second expansion valve to close, that is, control the opening degree of the second expansion valve to 0, so that the refrigerant flow through the inverter is 0, thus stopping the cooling of the inverter.

[0099] If the inverter temperature is greater than the fifth threshold T5 but less than the sixth threshold T6, the opening of the second expansion valve is controlled according to the second preset rule, where the sixth threshold T6 is greater than the fifth threshold T5. The second preset rule may include a preset relationship between the inverter temperature and the opening of the second expansion valve; it may also include a preset stepped opening control method, such as a certain opening corresponding to a certain inverter temperature range.

[0100] If the inverter temperature is greater than or equal to the sixth threshold T6, it indicates that the inverter temperature is too high and the inverter operation needs to be stopped immediately. The second temperature control device will then control the compressor to stop.

[0101] This application sets different temperature thresholds T5 and T6, and controls the opening of the second expansion valve or the compressor to stop according to different inverter temperatures. This can effectively cool the inverter, thereby improving the working efficiency of the chiller unit and extending the service life of the inverter.

[0102] The following embodiments illustrate two methods for controlling the opening degree of the second expansion valve according to a second preset rule.

[0103] In some embodiments, controlling the opening degree of the second expansion valve according to the second preset rule includes:

[0104] S601: If the inverter temperature is less than or equal to the seventh threshold, then control the second expansion valve to decrease from its current opening until the inverter temperature is greater than the seventh threshold, wherein the seventh threshold is greater than the fifth threshold and less than the sixth threshold.

[0105] S603: If the inverter temperature is greater than or equal to the eighth threshold, then control the second expansion valve to increase from its current opening until the inverter temperature is less than the eighth threshold, wherein the eighth threshold is greater than the seventh threshold and less than the sixth threshold.

[0106] In this embodiment, if the inverter temperature is controlled between the seventh threshold T7 and the eighth threshold T8, the inverter's operating efficiency is high. Therefore, if the inverter temperature is less than or equal to the seventh threshold T7 and greater than the fifth threshold T5, the second expansion valve is controlled to decrease its opening, reducing the refrigerant flow through the inverter and causing the inverter temperature to rise until it exceeds the seventh threshold T7, where the seventh threshold T7 is greater than the fifth threshold T5 and less than the sixth threshold T6. On the other hand, if the inverter temperature is greater than or equal to the eighth threshold T8 and less than the sixth threshold T6, the second expansion valve is controlled to increase its opening, increasing the refrigerant flow through the inverter and causing the inverter temperature to decrease until it falls below the eighth threshold T8, where the eighth threshold T8 is greater than the seventh threshold T7 and less than the sixth threshold T6.

[0107] In this embodiment, by adjusting the opening of the second expansion valve through the second temperature control device, the inverter temperature can be controlled between the seventh threshold T7 and the eighth threshold T8, which can effectively improve the operating efficiency of the inverter while preventing the inverter temperature from becoming too high.

[0108] In other embodiments, controlling the opening degree of the second expansion valve according to the second preset rule further includes:

[0109] S701: Determine a second opening degree that matches the inverter temperature according to a second preset relationship, wherein the second preset relationship includes a preset linear relationship between the inverter temperature and the second expansion valve opening degree.

[0110] S703: Control the opening degree of the second expansion valve according to the second opening degree.

[0111] In this embodiment, the second preset relationship may further include a preset linear relationship between the inverter temperature and the opening degree of the second expansion valve. In some specific embodiments, if the preset inverter temperature range includes a fifth threshold T5 to a sixth threshold T6, and the second opening degree of the second expansion valve is 0 to 100%, then the second opening degree corresponding to the inverter temperature being the fifth threshold T5 can be 0, and the second opening degree corresponding to the inverter temperature being the sixth threshold T6 can be 100%. Therefore, the inverter temperature between the fifth threshold T5 and the sixth threshold T6 can have a linear correspondence with the second opening degree of the second expansion valve between 0 and 100%. In other embodiments, the second opening degree of the second expansion valve within the range of 0 to 100% can also have a linear relationship with the inverter temperature within other temperature threshold ranges. This application does not limit the specific method for determining the preset linear relationship and can set it according to the actual application scenario.

[0112] In this embodiment, by using a linear relationship, a matching second opening degree can be determined based on the inverter temperature, and then the opening degree of the second expansion valve can be controlled based on the second opening degree. This can improve the control efficiency of the inverter temperature and also control the inverter temperature more accurately.

[0113] The following example, using an air-suspension compressor, illustrates the temperature control method of a frequency converter through a specific embodiment. Figure 5 As shown, the second temperature detection device acquires the inverter temperature Tu of the air-suspension compressor and sends it to the second temperature control device. If the inverter temperature Tu is less than or equal to the fifth threshold T5, the second temperature control device controls the second expansion valve to close, i.e., shuts down the inverter cooling system. If the inverter temperature Tu is greater than T5 and less than T6, the second temperature control device controls the second expansion valve to open, i.e., turns on the inverter cooling system. Specifically, if the inverter temperature Tu is less than or equal to the seventh threshold T7, the opening of the second expansion valve is reduced until the inverter temperature is greater than the seventh threshold T7; if the inverter temperature Tu is greater than or equal to the eighth threshold T8, the opening of the second expansion valve is increased until the inverter temperature Tu is less than the eighth threshold T8, thereby maintaining the inverter temperature between T7 and T8. If the inverter temperature is greater than or equal to the sixth threshold T6, the second temperature control device controls the inverter to shut down.

[0114] The following embodiment of this application provides another cooling branch configuration. The chiller unit includes a frequency converter, a compressor, a condenser, and an evaporator; the compressor, condenser, and evaporator are sequentially connected end-to-end to form a loop; the frequency converter is connected to the compressor; the cooling branch includes a third branch, a fourth branch, and a fifth branch; a third expansion valve is provided on the third branch; the inlet of the third expansion valve is connected to the outlet of the condenser; the inlet of the fourth branch is connected to the outlet of the third expansion valve, and the outlet of the fourth branch is connected to the inlet of the evaporator; the fourth branch passes through the motor of the compressor, and is used to cool the motor of the compressor; the inlet of the fifth branch is connected to the outlet of the third expansion valve, and the outlet of the fifth branch is connected to the inlet of the evaporator; the fifth branch passes through the frequency converter, and is used to cool the frequency converter.

[0115] In this embodiment of the application, if both a branch for cooling the motor and a branch for cooling the frequency converter are provided, the two branches can share a third expansion valve for pressure reduction and refrigerant flow control. Figure 4Taking the cooling system as an example, the first expansion valve 208 and the second expansion valve 207 can be replaced with a third expansion valve, and the third expansion valve is set on the common branch of the first branch and the second branch. The refrigerant flow in the first branch and the second branch is controlled by the third expansion valve. Specifically, the third expansion valve can be controlled by referring to the method of controlling the motor temperature in the above embodiment, or by referring to the method of controlling the inverter temperature in the above embodiment. Alternatively, the opening degree of the third expansion valve can be controlled by comprehensively considering the motor temperature and the inverter temperature according to the actual application scenario. This application does not impose specific restrictions on the method of controlling the opening degree of the third expansion valve.

[0116] In this embodiment, since the frequency converter can control the motor speed, the working intensity of the frequency converter and the motor is usually similar. By setting a third expansion valve to control the temperature of both the frequency converter and the motor, the cost of setting up the cooling branch can be saved on the one hand, and the efficiency of temperature control of the frequency converter and the motor can be improved on the other hand.

[0117] It should be understood that although the steps in the flowcharts of the embodiments described above are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the embodiments described above may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages of other steps.

[0118] Unless otherwise defined, the technical or scientific terms used in this application shall have the general meaning as understood by one of ordinary skill in the art to which this application pertains. Words such as “a,” “an,” “an,” “the,” “the,” and “these,” used in this application, do not indicate quantitative limitation and may be singular or plural. The terms “comprising,” “including,” “having,” and any variations thereof used in this application are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or device that comprises a series of steps or modules (units) is not limited to the listed steps or modules (units) but may include steps or modules (units) not listed, or may include other steps or modules (units) inherent to such processes, methods, products, or devices. The terms “connected,” “linked,” and “coupled,” used in this application, are not limited to physical or mechanical connections but may include electrical connections, whether direct or indirect. The term “multiple” used in this application refers to two or more. The "and / or" operator describes the relationship between related objects, indicating that three relationships can exist. For example, "A and / or B" can represent three cases: A alone, A and B simultaneously, and B alone. Typically, the character " / " indicates that the objects before and after it are in an "or" relationship. The terms "first," "second," and "third," etc., used in this application are merely for distinguishing similar objects and do not represent a specific ordering of the objects.

[0119] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM). The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, etc., and are not limited to these.

[0120] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0121] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A cooling system for a water chiller unit, characterized in that, The system includes a main circuit and cooling branch circuits; the main circuit includes a compressor, a condenser, and an evaporator; the compressor, condenser, and evaporator are connected end-to-end in sequence to form a circuit; The cooling branch includes a first branch, on which a first expansion valve is provided; The inlet of the first branch is connected to the outlet of the condenser, and the outlet of the first branch is connected to the inlet of the evaporator; the first branch passes through the motor of the compressor and is used to cool the motor of the compressor.

2. The system according to claim 1, characterized in that, The system further includes a first temperature control device, and the compressor is equipped with a first temperature detection device. The first temperature control device is connected to both the first temperature detection device and the first expansion valve. The first temperature detection device is used to detect the motor temperature and send the data to the first temperature control device; The first temperature control device is used to control the opening degree of the first expansion valve according to the motor temperature.

3. The system according to claim 2, characterized in that, The first temperature control device is also connected to the compressor, and controlling the opening degree of the first expansion valve according to the motor temperature includes: If the motor temperature is less than or equal to the first threshold, then the first expansion valve is controlled to close. If the motor temperature is greater than the first threshold and less than the second threshold, the opening degree of the first expansion valve is controlled according to the first preset rule, wherein the second threshold is greater than the first threshold. If the motor temperature is greater than or equal to the second threshold, the compressor is controlled to stop.

4. The system according to claim 3, characterized in that, The step of controlling the opening degree of the first expansion valve according to the first preset rule includes: If the motor temperature is less than or equal to the third threshold, then the first expansion valve is controlled to decrease from its current opening until the motor temperature is greater than the third threshold, wherein the third threshold is greater than the first threshold and less than the second threshold; If the motor temperature is greater than or equal to the fourth threshold, the first expansion valve is controlled to increase from its current opening until the motor temperature is less than the fourth threshold, wherein the fourth threshold is greater than the third threshold and less than the second threshold.

5. The system according to claim 3 or 4, characterized in that, The step of controlling the opening degree of the first expansion valve according to the first preset rule further includes: A first opening degree matching the motor temperature is determined according to a first preset relationship, wherein the first preset relationship includes a preset linear relationship between the motor temperature and the first expansion valve opening degree; The opening degree of the first expansion valve is controlled according to the first opening degree.

6. The system according to claim 1, characterized in that, The main circuit includes a frequency converter, which is connected to the compressor; The cooling branch also includes a second branch, on which a second expansion valve is provided; The inlet of the second branch is connected to the outlet of the condenser, and the outlet of the second branch is connected to the inlet of the evaporator; the second branch is arranged in parallel with the first branch; the second branch passes through the frequency converter and is used to cool the frequency converter.

7. The system according to claim 6, characterized in that, The system further includes a second temperature control device, and the frequency converter is equipped with a second temperature detection device. The second temperature control device is connected to both the second temperature detection device and the second expansion valve. The second temperature detection device is used to detect the inverter temperature and send the data to the second temperature control device; The second temperature control device is used to control the opening degree of the second expansion valve according to the temperature of the frequency converter.

8. The system according to claim 7, characterized in that, The second temperature control device is also connected to the frequency converter, and controlling the opening degree of the second expansion valve according to the temperature of the frequency converter includes: If the inverter temperature is less than or equal to the fifth threshold, then the second expansion valve is controlled to close. If the inverter temperature is greater than the fifth threshold and less than the sixth threshold, the opening of the second expansion valve is controlled according to the second preset rule, wherein the sixth threshold is greater than the fifth threshold. If the inverter temperature is greater than or equal to the sixth threshold, the compressor is controlled to stop.

9. The system according to claim 8, characterized in that, The step of controlling the opening degree of the second expansion valve according to the second preset rule includes: If the inverter temperature is less than or equal to the seventh threshold, the second expansion valve is controlled to decrease from its current opening until the inverter temperature is greater than the seventh threshold, which is greater than the fifth threshold and less than the sixth threshold. If the inverter temperature is greater than or equal to the eighth threshold, the second expansion valve is controlled to increase from its current opening until the inverter temperature is less than the eighth threshold, which is greater than the seventh threshold and less than the sixth threshold.

10. The system according to claim 8 or 9, characterized in that, The step of controlling the opening degree of the second expansion valve according to the second preset rule also includes: A second opening degree matching the inverter temperature is determined according to a second preset relationship, wherein the second preset relationship includes a preset linear relationship between the inverter temperature and the second expansion valve opening degree; The opening degree of the second expansion valve is controlled according to the second opening degree.

11. The system according to claim 1, characterized in that, The main circuit includes a frequency converter, which is connected to the compressor; The cooling branch includes a third branch, a fourth branch, and a fifth branch, and a third expansion valve is provided on the third branch; The inlet of the third expansion valve is connected to the outlet of the condenser; The inlet of the fourth branch is connected to the outlet of the third expansion valve, and the outlet of the fourth branch is connected to the inlet of the evaporator; the fourth branch passes through the motor of the compressor and is used to cool the motor of the compressor. The inlet of the fifth branch is connected to the outlet of the third expansion valve, and the outlet of the fifth branch is connected to the inlet of the evaporator; the fifth branch passes through the frequency converter and is used to cool the frequency converter.

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