Water chilling unit and control method thereof

Abstract

The embodiment of the invention provides a water chilling unit and a control method thereof, relates to the technical field of air conditioners, and aims to improve the cooling effect of a frequency converter. The water chilling unit comprises a refrigerant circulation loop; a frequency converter; a frequency conversion cooling pipeline; a gas-liquid separator; one end of the bypass pipeline is communicated with an outlet pipeline of the variable-frequency cooling pipeline, and the other end of the bypass pipeline is communicated with an inlet pipeline of the variable-frequency cooling pipeline; the controller is configured to obtain the compression ratio and cooling parameters of the water chilling unit; under the condition that the compression ratio is smaller than or equal to a first compression ratio threshold value and the cooling parameter does not reach a preset cooling index, a refrigerant in a refrigerant circulation loop is conveyed into a variable-frequency cooling pipeline through a gas-liquid separator; under the condition that the compression ratio is larger than or equal to a second compression ratio threshold value, the refrigerant in the frequency conversion cooling pipeline is conveyed into the evaporator through the bypass pipeline; and the amount of the refrigerant conveyed into the evaporator through the bypass pipeline is smaller than the total amount of the refrigerant in the variable-frequency cooling pipeline.

Description

Technical Field

[0001] This application relates to the field of air conditioning technology, and in particular to a chiller unit and its control method. Background Technology

[0002] During operation, the inverter of a chiller unit generates a lot of heat in its electronic components, such as insulated-gate bipolar transistors (IGBTs). If the heat cannot be dissipated in time, the inverter is prone to overheating and burning out.

[0003] The main cooling methods for inverters in existing chiller units include air cooling, water cooling, and refrigerant cooling. Air cooling has low heat dissipation efficiency, large size, high cost, and is prone to dust accumulation; water cooling systems are complex, prone to scaling, high cost, and have relatively low heat exchange efficiency; refrigerant cooling has high heat dissipation efficiency, simple and reliable structure, small size, and low cost. However, current chiller units typically use low-pressure, low-temperature refrigerants for cooling, connecting the refrigerant outlet pipe to the chiller unit's evaporator. This method has problems such as inverter condensation leading to electrical short circuits. Furthermore, this method only considers inverter cooling under normal operating conditions and does not address how to better cool the inverter under more complex operating conditions.

[0004] Therefore, improving the cooling effect of frequency converters has become an urgent technical problem to be solved. Summary of the Invention

[0005] This application provides a chiller unit and its control method for improving the cooling effect of a frequency converter.

[0006] To achieve the above objectives, this application adopts the following technical solution.

[0007] In a first aspect, embodiments of this application provide a chiller unit, comprising: a refrigerant circulation loop including a compressor, a condenser, a throttling device, and an evaporator; a frequency converter; a frequency converter cooling pipeline, one end of which is connected to the outlet pipeline of the frequency converter cooling pipeline, and the other end of which is connected to the inlet pipeline of the frequency converter cooling pipeline; a gas-liquid separator; a bypass pipeline, arranged in parallel with the frequency converter cooling pipeline, one end of which is connected to the condenser, and the other end of which is connected to the evaporator; and a controller configured to: acquire the compression ratio and cooling parameters of the chiller unit; the cooling parameters being used to characterize the cooling effect of the frequency converter; when the compression ratio is less than or equal to a first compression ratio threshold and the cooling parameters have not reached a preset cooling index, to transport the refrigerant in the refrigerant circulation loop to the frequency converter cooling pipeline through the gas-liquid separator; and when the compression ratio is greater than or equal to a second compression ratio threshold, to transport the refrigerant in the frequency converter cooling pipeline to the evaporator through the bypass pipeline; wherein the amount of refrigerant transported to the evaporator through the bypass pipeline is less than the total amount of refrigerant in the frequency converter cooling pipeline.

[0008] The technical solution provided in this application provides at least the following beneficial effects: This application provides a chiller unit that, when the chiller unit's compression ratio is less than or equal to a first compression ratio threshold (i.e., when the chiller unit's compression ratio is low), allows liquid refrigerant in the refrigerant circulation loop to be supplemented into the variable frequency cooling pipeline through a gas-liquid separator, thereby improving the inverter's cooling effect. Furthermore, when the chiller unit's compression ratio is greater than or equal to a second compression ratio threshold (i.e., when the chiller unit's compression ratio is high), the refrigerant in the variable frequency cooling pipeline can flow out through a bypass pipeline, allowing a portion of the refrigerant originally flowing into the variable frequency cooling pipeline to flow to the evaporator through the bypass pipeline. This maintains the amount of refrigerant in the variable frequency cooling pipeline within a suitable range, preventing over-cooling of the inverter, which could lead to excessively low inverter temperature and condensation, thus improving the cooling effect.

[0009] In this way, this control method can not only effectively meet the cooling needs of the chiller unit under various complex operating conditions, but also achieve better cooling effect under different operating conditions.

[0010] In some embodiments, the chiller unit further includes: a chiller unit, further including: a cooling device disposed on the variable frequency cooling pipeline for cooling the variable frequency drive; a liquid level detection device disposed on the gas-liquid separator for detecting the liquid level height of the gas-liquid separator; an ejector connected to the compressor exhaust port via a first liquid supply pipeline, connected to the bottom of the condenser via a second liquid supply pipeline, and connected to the gas-liquid separator via a third liquid supply pipeline; a liquid supply pipeline, one end connected to the bottom of the gas-liquid separator and the other end connected to the variable frequency cooling pipeline; a first branch, one end connected to the top of the gas-liquid separator and the other end connected to the evaporator; a first A valve is installed on the second replenishment line; a second valve is installed on the supply line; a controller is configured to deliver refrigerant in the refrigerant circulation loop to the variable frequency cooling line via a gas-liquid separator, including: controlling the first valve to open so that refrigerant in the condenser and refrigerant discharged from the compressor outlet are delivered to the gas-liquid separator via an ejector; wherein the amount of refrigerant discharged from the compressor outlet is less than the total amount of refrigerant in the compressor; and controlling the second valve to open when the liquid level detected by the liquid level detection device is greater than or equal to a first height threshold, so that the refrigerant in the gas-liquid separator flows to the variable frequency cooling line.

[0011] Understandably, this application provides a chiller unit where, when the chiller unit's compression ratio falls below a first compression ratio threshold (i.e., when the chiller unit's compression ratio is low), a first valve can be opened to allow the liquid refrigerant in the condenser to flow together with the gaseous refrigerant discharged from the compressor to the gas-liquid separator under the action of the ejector. When the liquid level detection device detects that the liquid level has reached a first height threshold, a second valve is opened to replenish the liquid refrigerant in the gas-liquid separator into the inverter cooling pipeline, thereby improving the inverter's cooling effect. Thus, when the chiller unit operates at a low compression ratio, the ejector replenishes the refrigerant in the condenser into the inverter cooling pipeline to cool the inverter, solving the problem of reduced refrigerant volume in the inverter cooling pipeline due to the small pressure difference between the evaporator and condenser, effectively improving the inverter's cooling effect.

[0012] In some embodiments, the chiller unit further includes: a second branch, one end of which is connected to a second replenishment pipeline and the other end of which is connected to an evaporator; a third valve, disposed on the second branch, for controlling the opening and closing of the second branch; and a controller configured to deliver refrigerant in the refrigerant circulation loop to the variable frequency cooling pipeline through a gas-liquid separator, including: detecting the liquid level height of the condenser; and, when the liquid level height of the condenser is detected to be less than or equal to a second height threshold, controlling the third valve to open so as to deliver the refrigerant in the evaporator and the refrigerant discharged from the compressor's exhaust port to the variable frequency cooling pipeline through the second branch; wherein the amount of refrigerant discharged from the compressor's exhaust port is less than the total amount of refrigerant in the compressor.

[0013] Understandably, this application provides a chiller unit where, when the chiller's compression ratio falls below a first compression ratio threshold (i.e., when the chiller's compression ratio is low), the condenser's liquid level can be determined before adding refrigerant to the variable frequency cooling pipes to ascertain whether the refrigerant in the condenser is sufficient. If the condenser's liquid level is detected to be less than or equal to a second height threshold, it can be determined that the refrigerant in the condenser is insufficient. In the case of insufficient refrigerant in the condenser, the third valve can be opened to add refrigerant from the evaporator into the variable frequency cooling pipes. Thus, it can be ensured that the variable frequency drive receives adequate cooling regardless of whether the condenser has refrigerant.

[0014] In some embodiments, the cooling parameters include at least one of the following: the change in the amount of refrigerant in the variable frequency cooling pipeline and the temperature of the variable frequency drive; the cooling parameters not reaching the preset cooling index include any one of the following: the change is a change used to indicate the decrease in the amount of refrigerant in the variable frequency cooling pipeline; the temperature of the variable frequency drive is greater than or equal to a first temperature threshold.

[0015] In some embodiments, the chiller unit further includes: an unloading valve, disposed on a bypass pipeline, for controlling the opening and closing of the bypass pipeline; when the pressure difference between the outlet of the variable frequency cooling pipeline and the inlet of the variable frequency cooling pipeline is greater than the preset opening pressure of the unloading valve, the unloading valve is in an open state, so that the refrigerant in the refrigerant circulation loop is transported to the evaporator through the bypass pipeline.

[0016] Understandably, this application provides a chiller unit that, when the chiller unit's compression ratio reaches or exceeds a second compression ratio threshold (i.e., when the chiller unit's compression ratio is high), adjusts the opening of the unloading valve to allow refrigerant to flow out through a bypass pipe. In this way, the bypass pipe is used to bypass a portion of the increased variable frequency drive refrigerant flow to maintain a suitable cooling liquid supply flow, thereby improving the inverter's cooling effect.

[0017] In some embodiments, the controller is further configured to: when the ambient humidity is greater than or equal to a humidity threshold, the ambient temperature is greater than or equal to a second temperature threshold, and the cooling parameters do not reach a preset cooling index, deliver the refrigerant in the refrigerant circulation loop to the variable frequency cooling pipeline through a gas-liquid separator.

[0018] Understandably, this application provides a chiller unit that can use an ejector to replenish the refrigerant in the condenser to the inverter cooling pipeline through a liquid replenishment pipeline under operating conditions of high ambient temperature and high humidity, thereby solving the problem of poor cooling effect of the inverter under operating conditions of high ambient temperature and high humidity and ensuring cooling effect.

[0019] In some embodiments, the chiller unit further includes: an economizer; a second branch, one end of which is connected to a second replenishment pipeline and the other end of which is connected to an evaporator; a first branch, one end of which is connected to the top of a gas-liquid separator and the other end of which is connected to an evaporator; a third branch, one end of which is connected to the top of a gas-liquid separator and the other end of which is connected to the economizer; a third valve, disposed on the second branch, for controlling the opening and closing of the second branch; a fourth valve, disposed on the first branch; a fifth valve, disposed on the third branch; and a controller further configured to: after controlling the second valve to be open for a first preset duration, and if the temperature of the frequency converter is detected to be greater than or equal to a first temperature threshold, control the first valve to be closed and the third valve to be opened, so that the refrigerant in the evaporator enters the frequency converter cooling pipeline through the second branch; and after controlling the first valve to be closed and the third valve to be open for a second preset duration, and if the temperature of the frequency converter is detected to be greater than or equal to the first temperature threshold, control the fifth valve to be opened and the fourth valve to be closed, so as to connect the return port of the gas-liquid separator to the economizer.

[0020] Understandably, this application provides a chiller unit where, if the inverter temperature remains greater than or equal to a first temperature threshold after the second valve has been opened for a first preset time, the current cooling effect is considered average. To further improve the cooling effect, the first valve can be closed and the third valve opened, allowing the cooler refrigerant in the evaporator to enter the inverter cooling pipe through the second branch. Since the refrigerant in the evaporator is at a lower temperature, cooling the inverter with this cooler refrigerant achieves a better cooling effect.

[0021] Furthermore, after the first valve is closed and the third valve is open for a second preset time, if the temperature of the inverter is still not below the first temperature threshold, the fifth valve is opened to change the component connected to the return port of the gas-liquid separator from the evaporator to the economizer, thereby increasing the pressure in the gas-liquid separator and increasing the amount of refrigerant input from the gas-liquid separator to the inverter cooling pipe, thus improving the cooling effect of the inverter.

[0022] In addition, this method allows for multiple adjustments, gradually improving the cooling effect and avoiding the possibility of overcooling leading to condensation or undercooling causing the inverter to overheat, which may occur with a one-size-fits-all liquid replenishment solution.

[0023] In some embodiments, the chiller unit further includes: a sixth valve disposed at the outlet of the variable frequency cooling pipeline; and a controller further configured to: control the sixth valve to close to stop cooling the variable frequency drive when the temperature of the variable frequency drive is detected to be less than or equal to a third temperature threshold.

[0024] It is understood that this application provides a chiller unit, which can be used to prevent the inverter from being overcooled by setting a sixth valve at the outlet of the inverter cooling pipeline, so as to avoid the problem of condensation caused by the inverter being too low in temperature.

[0025] In some embodiments, the chiller unit further includes: a seventh valve disposed at the outlet of the variable frequency cooling pipeline; an eighth valve disposed in parallel with the seventh valve; and a controller further configured to: increase the opening degree of the seventh valve when the temperature of the variable frequency drive is detected to be greater than or equal to a first temperature threshold; decrease the opening degree of the seventh valve when the temperature of the variable frequency drive is detected to be less than or equal to a third temperature threshold; and open the eighth valve when the ambient humidity is greater than or equal to a humidity threshold, the ambient temperature is greater than or equal to a second temperature threshold, the opening degree of the seventh valve is equal to the upper limit of the rated opening degree of the seventh valve, and the temperature of the variable frequency drive is greater than or equal to the first temperature threshold.

[0026] Understandably, this application provides a chiller unit that controls the opening of the seventh and eighth valves by detecting the temperature of the frequency converter. This not only adjusts the pressure at the outlet of the frequency converter cooling pipe to regulate the evaporation temperature—the lower the evaporation temperature, the better the cooling effect of the frequency converter—but also adjusts the refrigerant flow area to regulate the amount of refrigerant in the frequency converter cooling pipe.

[0027] Secondly, embodiments of this application provide a control method for a chiller unit. The method is applied to the chiller unit and includes: acquiring the compression ratio and cooling parameters of the chiller unit; the cooling parameters are used to characterize the cooling effect of the frequency converter; when the compression ratio is less than or equal to a first compression ratio threshold and the cooling parameters do not reach a preset cooling index, the refrigerant in the refrigerant circulation loop is transported to the frequency converter cooling pipeline through a gas-liquid separator; when the compression ratio is greater than or equal to a second compression ratio threshold, the refrigerant in the refrigerant circulation loop is transported to the evaporator through a bypass pipeline; wherein the amount of refrigerant transported to the evaporator through the bypass pipeline is less than the total amount of refrigerant in the frequency converter cooling pipeline.

[0028] Thirdly, embodiments of this application provide a controller, including: one or more processors; one or more memories; wherein the one or more memories are used to store computer program code, the computer program code including computer instructions, and when the one or more processors execute the computer instructions, the controller executes any of the chiller unit control methods provided in the second aspect.

[0029] Fourthly, embodiments of this application provide a computer-readable storage medium including computer instructions that, when executed on a computer, cause the computer to perform any of the chiller control methods provided in the second aspect.

[0030] Fifthly, embodiments of the present invention provide a computer program product that can be directly loaded into a memory and contains software code. After being loaded and executed by a computer, the computer program product can realize any of the control methods for chiller units provided in the second aspect.

[0031] It should be noted that the aforementioned computer instructions may be stored, in whole or in part, on a computer-readable storage medium. This computer-readable storage medium may be packaged together with the controller's processor, or it may be packaged separately from the controller's processor; this application does not impose any limitations on this.

[0032] The beneficial effects described in aspects two through five of this application can be referred to the analysis of the beneficial effects of aspect one, and will not be repeated here. Attached Figure Description

[0033] The accompanying drawings are provided to further understand the technical solutions of the present invention and constitute a part of the specification. They are used together with the embodiments of this application to explain the technical solutions of the present invention and do not constitute a limitation on the technical solutions of the present invention.

[0034] Figure 1 This is a schematic diagram of the structure of a chiller unit provided in an embodiment of this application;

[0035] Figure 2 This is a schematic diagram of another chiller unit provided in an embodiment of this application;

[0036] Figure 3 This is a schematic diagram of another chiller unit provided in an embodiment of this application;

[0037] Figure 4 This is a schematic diagram of another chiller unit provided in an embodiment of this application;

[0038] Figure 5 This is a schematic diagram of another chiller unit provided in an embodiment of this application;

[0039] Figure 6 This is a schematic diagram of another chiller unit provided in an embodiment of this application;

[0040] Figure 7 This is a schematic diagram of another chiller unit provided in an embodiment of this application;

[0041] Figure 8 This is a schematic diagram of another chiller unit provided in an embodiment of this application;

[0042] Figure 9 This is a schematic diagram of another chiller unit provided in an embodiment of this application;

[0043] Figure 10 This is a schematic diagram of another chiller unit provided in an embodiment of this application;

[0044] Figure 11 This is a schematic diagram of another chiller unit provided in an embodiment of this application;

[0045] Figure 12 This is a schematic diagram of another chiller unit provided in an embodiment of this application;

[0046] Figure 13 This is a schematic diagram of another chiller unit provided in an embodiment of this application;

[0047] Figure 14 This is a schematic diagram of the structure of a frequency converter cabinet provided in an embodiment of this application;

[0048] Figure 15A flowchart illustrating a control method for a chiller unit provided in this application embodiment;

[0049] Figure 16 A flowchart illustrating another control method for a chiller unit provided in this application embodiment;

[0050] Figure 17 A flowchart illustrating another control method for a chiller unit provided in this application embodiment;

[0051] Figure 18 A flowchart illustrating another control method for a chiller unit provided in this application embodiment;

[0052] Figure 19 A flowchart illustrating another control method for a chiller unit provided in this application embodiment;

[0053] Figure 20 A flowchart of another control method for a chiller unit provided in an embodiment of this application. Detailed Implementation

[0054] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0055] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0056] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0057] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "connected" and "linked" should be interpreted broadly, for example, as a fixed connection, a detachable connection, or an integral connection. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances. Furthermore, when describing pipelines, the terms "connected" and "linked" as used in this application have the meaning of establishing electrical connection. The specific meaning needs to be understood in conjunction with the context.

[0058] In the embodiments of this application, the terms "exemplary" or "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design that is described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design. Specifically, the use of the terms "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0059] To improve the cooling effect of the frequency converter, this application provides a control method for a chiller unit. When the chiller unit's compression ratio is less than or equal to a first compression ratio threshold (i.e., when the chiller unit's compression ratio is low), liquid refrigerant in the refrigerant circulation loop is supplemented into the frequency converter's cooling pipes via a gas-liquid separator to improve the inverter's cooling effect. Alternatively, when the chiller unit's compression ratio is greater than or equal to a second compression ratio threshold (i.e., when the chiller unit's compression ratio is high), refrigerant can be bypassed through a bypass pipe. This allows a portion of the refrigerant originally flowing into the frequency converter's cooling pipes to flow to the evaporator via the bypass pipe, maintaining the amount of refrigerant in the frequency converter's cooling pipes within a suitable range. This prevents overcooling of the frequency converter, which could lead to excessively low inverter temperatures and condensation, thus improving the cooling effect.

[0060] In this way, this control method can not only effectively meet the cooling needs of the chiller unit under various complex operating conditions, but also achieve better cooling effect under different operating conditions.

[0061] Figure 1 This is a schematic diagram of the structure of a chiller unit provided in accordance with an exemplary embodiment of this application. Figure 1 As shown, the chiller unit 100 includes a compressor 101, a condenser 102, an evaporator 103, a throttling device 104, an economizer 105, and a controller 106. Figure 1 (Not shown in the image).

[0062] In some embodiments, the compressor 101, condenser 102, throttling device 104, economizer 105, and evaporator 103 are connected to form a refrigerant circulation loop. In this embodiment, other devices may also be included between the various components. For example, a check valve may be installed on the pipeline between the compressor 101 and the condenser 102.

[0063] In some embodiments, compressor 101 is a driven fluid machine that boosts low-pressure refrigerant to high-pressure refrigerant, providing power for refrigerant circulation. The compressor has an intake port, an exhaust port, and a make-up air port. A portion of the refrigerant from evaporator 103 enters compressor 101 through the intake port, and another portion of the refrigerant from economizer 105 enters compressor 101 through the make-up air port. Within compressor 101, the refrigerant is compressed into a high-temperature, high-pressure gaseous refrigerant, which is then discharged from the exhaust port of compressor 101.

[0064] In some embodiments, the controller 106 can adjust the amount of refrigerant entering the compressor 101 from the suction port by adjusting the frequency of the compressor 101 and the opening of the guide vanes at the suction port.

[0065] In some embodiments, the inlet of the condenser 102 is connected to the compressor 101, and the outlet of the condenser 102 is connected to the inlet of the economizer 105, for condensing the high-temperature and high-pressure gaseous refrigerant discharged from the compressor 101 into a high-temperature and high-pressure liquid refrigerant, thereby completing the heat dissipation process.

[0066] In some embodiments, the inlet of the evaporator 103 is connected to the first outlet of the economizer 105, and the outlet of the evaporator 103 is connected to the inlet of the compressor 101, for evaporating the liquid refrigerant into the gaseous refrigerant to complete the heat absorption process.

[0067] In some embodiments, the throttling device 104 is used to adjust the fluid velocity in the refrigerant circulation pipeline of the chiller unit 100 and to adjust the refrigerant flow rate.

[0068] In some embodiments, the economizer 105 is a heat exchanger. The economizer has an inlet, a first outlet, and a second outlet, the first outlet being connected to the inlet of the evaporator 103, and the second outlet being connected to the air supply port of the compressor 101.

[0069] In some embodiments, controller 106 refers to a device that can generate operation control signals based on instruction opcodes and timing signals to instruct the chiller unit to execute control commands. Exemplarily, the controller can be a central processing unit (CPU), a network processor (NP), a digital signal processor (DSP), a microprocessor, a microcontroller, a programmable logic device (PLD), or any combination thereof. The controller can also be other devices with processing capabilities, such as circuits, devices, or software modules; this application embodiment does not impose any limitations on this.

[0070] In addition, the controller 106 is used to control the operation of various components inside the chiller unit 100 so that each component of the chiller unit 100 can perform its predetermined functions.

[0071] For example, such as Figure 2 As shown, the refrigerant circulation flow in the refrigerant loop is as follows: the low-temperature, low-pressure gaseous refrigerant flowing out of the evaporator 103 is compressed by the first-stage impeller of the compressor 101, and then mixed with the medium-temperature, medium-pressure saturated gas from the economizer 105. It is then further compressed by the second-stage impeller of the compressor 101, becoming a high-temperature, high-pressure gaseous refrigerant. Afterward, the high-temperature, high-pressure gaseous refrigerant enters the condenser 102, where it is cooled by the cooling water and transformed into a high-temperature, high-pressure liquid refrigerant. The high-temperature, high-pressure liquid refrigerant is depressurized by the throttling device 104 and enters the economizer 105, where it is separated into saturated liquid refrigerant and flashing gaseous refrigerant. The gaseous refrigerant enters the compressor 101 through the second outlet and is compressed by the second-stage impeller of the compressor 101. The liquid refrigerant, after being depressurized by the throttling device, enters the evaporator 103, becoming a low-temperature, low-pressure liquid refrigerant, thus forming a main cycle.

[0072] In some embodiments, the chiller unit 100 may also include a frequency converter.

[0073] In some embodiments, the frequency converter can be installed in the mounting space within a frequency converter cabinet. A frequency converter is a power control device that uses frequency conversion technology and microelectronics to control an AC motor by changing the frequency of the motor's operating power supply. A frequency converter mainly consists of a rectification (AC to DC) unit, a filtering unit, an inverter (DC to AC) unit, a braking unit, a drive unit, a detection unit, and a microprocessor unit. The frequency converter adjusts the voltage and frequency of the output power supply by switching its internal IGBTs, providing the required power voltage according to the actual needs of the motor, thereby achieving energy saving and speed regulation. In addition, the frequency converter has many protection functions, such as overcurrent, overvoltage, and overload protection.

[0074] Understandably, during the operation of a frequency converter, heat is generated due to internal losses. When the ambient temperature is too high, the temperature of the frequency converter can reach 80-90℃. Because electronic components are installed inside the frequency converter, excessive temperature can easily lead to the failure of these components. Therefore, cooling measures are needed to prevent the frequency converter from overheating.

[0075] In some embodiments, in order to cool the frequency converter, such as Figure 3 As shown, the chiller unit provided in this application embodiment may further include a variable frequency cooling pipeline 301 and a cooling device 302.

[0076] In some embodiments, one end of the variable frequency cooling pipe 301 is connected to the condenser 102, and the other end of the variable frequency cooling pipe 301 is connected to the evaporator 103.

[0077] In some embodiments, the cooling device 302 can be installed in the mounting space within the frequency converter cabinet 303, positioned close to the frequency converter. The cooling device 302 has a channel for containing and circulating refrigerant. The refrigerant in the frequency converter cooling pipe 301 can flow through this pipe into the cooling device 302. Therefore, when the frequency converter is operating, the heat generated by the frequency converter can exchange heat with the refrigerant flowing in the cooling device 302, thereby cooling the frequency converter.

[0078] The following is an example illustrating the specific process of cooling the frequency converter. Refrigerant from the condenser, under the pressure difference between the evaporator 103 and the condenser 102, flows through the frequency converter cooling pipe 301 and into the cooling device 302. This refrigerant exchanges heat with the air inside the frequency converter and the frequency converter cabinet, causing a phase change and carrying away heat from the frequency converter, thus achieving the effect of cooling it.

[0079] In some embodiments, such as Figure 4 As shown, the variable frequency cooling pipeline 301 includes a variable frequency cooling inlet main pipeline 401, a variable frequency cooling outlet main pipeline 402, a first variable frequency cooling branch pipeline 403, and a second variable frequency cooling branch pipeline 404. The cooling device 302 includes a cold plate 405 and a heat exchanger 406.

[0080] In some embodiments, the cold plate 405 may be disposed on the first variable frequency cooling branch 403 or the second variable frequency cooling branch 404. The heat exchanger 406 may be disposed on the first variable frequency cooling branch 403 or the second variable frequency cooling branch 404. The embodiments of this application do not specifically limit the positions of the cold plate 405 and the heat exchanger 406.

[0081] For example, when the cold plate 405 is provided on the first variable frequency cooling branch 403, the heat exchanger 406 is provided on the second variable frequency cooling branch 404. When the cold plate 405 is provided on the second variable frequency cooling branch 404, the heat exchanger 406 is provided on the first variable frequency cooling branch 403.

[0082] The chiller unit 100 will be described in detail below, with the cold plate 405 installed on the first variable frequency cooling branch 403 and the heat exchanger 406 installed on the second variable frequency cooling branch 404.

[0083] In some embodiments, the main variable frequency cooling inlet 401 can be split into a first variable frequency cooling branch 403 and a second variable frequency cooling branch 404 within the variable frequency cabinet 303.

[0084] In some embodiments, the first variable frequency cooling branch 403 and the second variable frequency cooling branch 404 can be combined outside the variable frequency cabinet 303 to form the variable frequency cooling outlet main line 402, which is connected to the evaporator 103.

[0085] In some embodiments, a channel is formed inside the cold plate 405 for containing and allowing the refrigerant to circulate within it. Because the cold plate 405 has good thermal conductivity, when the temperature of the inverter is higher than the temperature of the refrigerant inside the cold plate 405, heat from the inverter is transferred to the refrigerant inside the cold plate 405, thus cooling the inverter.

[0086] Optionally, the 405 cold-rolled steel plate can be made of copper or aluminum, or any other metal with good thermal conductivity.

[0087] In some embodiments, the cold plate 405 can be positioned in close contact with the frequency converter to improve the cooling effect.

[0088] In some embodiments, a throttling device may be provided at the inlet of the cold plate 405 so that the refrigerant can undergo phase change heat within the cold plate 405.

[0089] In some embodiments, a heat exchanger 406 is disposed inside the frequency converter cabinet 303 to cool and dehumidify the air inside the frequency converter cabinet 303, thereby cooling the frequency converter.

[0090] In some embodiments, heat exchanger 406 may be a finned heat exchanger. The finned heat exchanger includes a fan 407, which enhances the cooling and dehumidification effect on the air inside the inverter cabinet 303. The operation of the fan 407 circulates the air inside the inverter cabinet 303, achieving a better and more uniform cooling and dehumidification effect.

[0091] In some embodiments, if the blowing angle of the fan 407 is not appropriate, a large amount of uncooled and undehumidified hot air may flow to the top of the inverter cabinet 303, causing condensation and posing a hazard. Therefore, the airflow path can be simulated according to the installation space configuration within the inverter cabinet 303 to change the blowing angle of the fan 407, adjust the position of components, and install guide vanes, thereby altering the airflow path and minimizing the flow of uncooled and undehumidified hot air to the top of the inverter cabinet 303, thus preventing condensation.

[0092] In some embodiments, the component in the frequency converter cabinet 303 that most needs cooling is the frequency converter. To improve the cooling effect of the frequency converter, such as... Figure 5 As shown in the embodiment of this application, the chiller unit may further include a ninth valve 501.

[0093] Optionally, the ninth valve 501 can be an electrically operated shut-off valve or an electrically operated regulating valve.

[0094] In some embodiments, a ninth valve 501 is disposed on the second frequency conversion cooling branch 404 for controlling the opening and closing of the second frequency conversion cooling branch 404.

[0095] In some embodiments, when the controller 106 detects that the temperature of the frequency converter has reached or exceeded the high temperature warning threshold, it can control the ninth valve 501 to close or control the opening of the ninth valve 501 to decrease, thereby increasing the amount of refrigerant in the first frequency converter cooling branch 403, improving the cooling effect of the frequency converter, removing more heat from the frequency converter, and lowering the temperature of the frequency converter.

[0096] In some embodiments, the controller 106 may control the ninth valve 501 to open or control the opening degree of the ninth valve 501 to increase when the temperature of the inverter drops below the high temperature warning threshold, thereby reducing the amount of refrigerant in the first inverter cooling branch 403, resulting in a decrease in the cooling effect of the inverter, making it unable to effectively remove heat, and causing the temperature of the inverter to rise again.

[0097] When the chiller unit 100 operates at a low compression ratio, the pressure difference between the evaporator 103 and the condenser 102 is small, resulting in a reduction in the amount of refrigerant in the inverter's cooling pipes and a decrease in cooling efficiency. To address this issue, such as... Figure 6 As shown, the chiller unit provided in the exemplary embodiment of this application may further include an ejector 601, a gas-liquid separator 602, a first valve 603, a second valve 604, a liquid supply pipeline 605, a first branch 606, and a throttling device 607.

[0098] In some embodiments, the ejector 601 is connected to the exhaust port of the compressor 101 via a first replenishment line, to the bottom of the condenser 102 via a second replenishment line, and to the gas-liquid separator 602 via a third replenishment line. The ejector 601 is used to deliver the liquid refrigerant in the condenser 102 and the gaseous refrigerant discharged from the compressor 101 together to the gas-liquid separator 602.

[0099] In some embodiments, the refrigerant in the gas-liquid separator 602 can flow to the main inlet 401 of the frequency converter cooling through the liquid supply line 605 under the action of pressure difference, so as to supplement the amount of refrigerant flowing in the cold plate 405 and the heat exchanger 406, that is, to supplement the amount of refrigerant cooling the frequency converter.

[0100] In some embodiments, one end of the liquid supply line 605 is connected to the bottom of the gas-liquid separator 602, and the other end is connected to the main variable frequency cooling inlet 401, so that the liquid refrigerant in the gas-liquid separator 602 can flow to the main variable frequency cooling inlet 401 through the liquid supply line 605.

[0101] In some embodiments, a first valve 603 is disposed on a second replenishment pipeline for controlling the opening and closing of the second supply pipeline.

[0102] In some embodiments, the second valve 604 is disposed on the liquid supply line and is used to control the opening and closing of the liquid supply line.

[0103] In some embodiments, one end of the first branch 606 is connected to the top of the gas-liquid separator 602, and the other end is connected to the evaporator 103, so that the gaseous refrigerant in the gas-liquid separator 602 can flow to the evaporator 103 through the first branch 606.

[0104] In some embodiments, the throttling device 607 is provided on the first branch to regulate the fluid flow rate in the first branch 606 and to regulate the refrigerant flow rate, thereby ensuring that the pressure of the gas-liquid separator 602 is higher than the pressure of the variable frequency cooling inlet main branch 401.

[0105] based on Figure 6 The chiller unit shown below exemplifies the cooling process of the inverter when the chiller unit 100 is operating at a low compression ratio. The controller 106 controls the opening of the first valve 603, allowing the liquid refrigerant in the condenser 102 to flow together with the gaseous refrigerant discharged from the compressor 101's exhaust port into the gas-liquid separator 602 under the ejector action of the ejector 601. The gaseous refrigerant in the gas-liquid separator 602 flows to the evaporator 103, and under the action of the throttling device 607, the pressure in the gas-liquid separator 602 is made higher than the pressure in the main inlet 401 of the inverter cooling system.

[0106] After a set time, controller 106 controls the second valve 604 to open, allowing the liquid refrigerant in gas-liquid separator 602 to replenish the main inverter cooling inlet 401 under the pressure difference between gas-liquid separator 602 and the main inverter cooling inlet 401. This replenishes the refrigerant supply for cooling the inverter and improves its cooling effect. This solves the problem of reduced refrigerant supply and decreased cooling effect in the inverter cooling pipes when the chiller unit 100 operates at a low compression ratio due to the smaller pressure difference between evaporator 103 and condenser 102.

[0107] In the embodiments of this application, other devices may also be included between the various devices. For example, such as Figure 7 As shown, a one-way valve 701 can be installed on the liquid supply line 605 to prevent the refrigerant flowing to the main line 401 of the frequency converter cooling inlet from flowing back into the gas-liquid separator 602.

[0108] In some embodiments, based on Figure 8The chiller unit shown can also control the opening of the first valve 603 and the second valve 604 when the chiller unit 100 is operating under conditions of high ambient temperature and humidity, and the temperature of the frequency converter is detected to be above the high temperature warning threshold. Regarding the process of cooling the frequency converter, please refer to the specific process of cooling the frequency converter when the chiller unit 100 is operating under conditions of low compression ratio, which will not be elaborated upon here.

[0109] In some embodiments, such as Figure 8 As shown in the embodiments of this application, the chiller unit may further include a liquid level detection device 801.

[0110] In some embodiments, a liquid level detection device 801 is installed on a gas-liquid separator 602 to detect the liquid level of the refrigerant inside the gas-liquid separator 602.

[0111] Optionally, the level detection device 801 can be a level switch.

[0112] based on Figure 8 The chiller unit shown below illustrates the cooling process of the inverter when the chiller unit 100 is operating under conditions of low compression ratio. When the chiller unit 100 includes a liquid level detection device 801, the controller 106 can, after controlling the first valve 603 to open, and upon the liquid level detection device 801 detecting that the liquid level has reached a first height threshold, control the second valve 604 to open. This allows the liquid refrigerant in the gas-liquid separator 602 to be replenished into the inverter cooling inlet main line 401 under the pressure difference between the gas-liquid separator 602 and the inverter cooling inlet main line 401, thereby supplementing the refrigerant quantity for cooling the inverter and improving its cooling effect.

[0113] When the chiller unit 100 operates at a high compression ratio, the large pressure difference between the evaporator 103 and the condenser 102 increases the amount of refrigerant in the inverter's cooling pipes. This can lead to over-cooling of the inverter, resulting in excessively low temperatures and condensation. Condensation on the inverter can easily cause short-circuit faults or even burn out the inverter. To solve this problem, such as... Figure 9 As shown, the chiller unit provided in the exemplary embodiment of this application may further include a bypass pipeline 901 and an unloading valve 902.

[0114] In some embodiments, the bypass pipe 901 is connected in parallel with the frequency converter cooling pipe 301, with one end connected to the frequency converter cooling inlet main line 401 (i.e., the inlet pipe of the frequency converter cooling pipe) and the other end connected to the frequency converter cooling outlet main line 402 (i.e., the outlet pipe of the frequency converter cooling pipe).

[0115] For example, the bypass pipe 901 can be connected in parallel with the first frequency converter cooling branch 403 and the second frequency converter cooling branch 404.

[0116] In some embodiments, the number of bypass lines 901 can be determined based on the pressure difference range between the evaporator 103 and the condenser 102 and the gradient of the preset opening pressure of the unloading valve 902.

[0117] In some embodiments, the number of bypass pipes 901 can be one or more; this application does not specifically limit the number of bypass pipes 901. For example, such as... Figure 10 As shown, there can be three bypass lines 901. For example, bypass lines 1, 2, and 3 can be installed, along with unloading valves 1, 2, and 3. The opening pressure of unloading valve 1 is lower than that of unloading valve 2, and the opening pressure of unloading valve 2 is lower than that of unloading valve 3.

[0118] In some embodiments, the diameter of the bypass pipe 901 is smaller than the diameter of the frequency converter cooling inlet main pipe 401 and the frequency converter cooling outlet main pipe 402.

[0119] In some embodiments, the diameter of the bypass pipe 901 can be determined based on parameters such as the amount of refrigerant that needs to be bypassed (i.e., the amount of refrigerant flowing to the variable frequency cooling pipe is reduced through the bypass pipe 901), the preset opening pressure of the unloading valve 902, and the difference between the preset opening pressure of the unloading valve 902 and the maximum pressure difference between the evaporator 103 and the condenser 102 of the chiller unit 100 under normal operating conditions.

[0120] In some embodiments, the diameter of the bypass pipe 901 can be modified according to actual test conditions and the actual route of the bypass pipe 901, which affect the pressure loss of the bypass pipe 901.

[0121] In some embodiments, the unloading valve 902 is provided on the bypass line 901 to control the opening and closing of the bypass line 901.

[0122] In some embodiments, the amount of refrigerant in the variable frequency cooling pipeline 301 fluctuates within a suitable range before and after the unloading valve 902 is opened.

[0123] In some embodiments, when the pressure difference between the evaporator 103 and the condenser 102 is large, the amount of refrigerant in the inverter cooling pipe will increase. By controlling the opening and closing of the unloading valve 902, a portion of the refrigerant that originally flowed to the inverter cooling pipe 301 can flow to the evaporator 103 through the bypass pipe, so that the amount of refrigerant in the inverter cooling pipe 301 is maintained within a suitable range.

[0124] In some embodiments, the unloading valve 902 has a preset opening pressure. When the refrigerant pressure reaches or exceeds the preset opening pressure, the unloading valve 902 opens to allow the bypass line 901 to be opened.

[0125] In some embodiments, the unloading valve 902 may be a mechanical pressure relief valve, an electric valve, or an electronic expansion valve.

[0126] In one example, when the unloading valve 902 is a mechanical pressure relief valve, the controller 106 can control the opening and closing of the pressure relief valve according to the relationship between the pressure difference between the evaporator 103 and the condenser 102 and the preset opening pressure of the unloading valve 902, so as to control the opening and closing of the bypass pipe 901, thereby maintaining the amount of refrigerant in the variable frequency cooling pipe 301 within a suitable range.

[0127] In another example, under complex operating conditions, such as low ambient temperature and high humidity, condensation can easily occur inside the inverter cabinet due to its airtightness. Furthermore, the preset opening pressure of the mechanical pressure relief valve, determined under normal operating conditions, may not be applicable under complex conditions, potentially causing the bypass circuit to open at inappropriate times, leading to over-cooling of the inverter and condensation. Therefore, to solve this technical problem, the electric valve can be configured as an unloading valve 902. The controller 106 can control the opening and closing of the electric valve based on the inverter temperature to control the opening and closing of the bypass line 901, thereby maintaining the amount of refrigerant in the inverter cooling line 301 within a suitable range.

[0128] Understandably, setting the electric valve as an unloading valve 902 can effectively cool the frequency converter even under the complex operating conditions of the chiller unit.

[0129] In another example, when the unloading valve 902 is an electronic expansion valve, the inverter can be cooled more precisely. The controller 106 can adjust the opening degree of multiple unloading valves or control the opening or closing of the electronic expansion valve based on the inverter temperature to control the conduction and cutoff of the bypass line 901, thereby maintaining the amount of refrigerant in the inverter cooling line 301 within a suitable range.

[0130] In some embodiments, to further improve the cooling effect, such as Figure 11 As shown, the chiller unit provided in the exemplary embodiment of this application may further include a second branch 1101, a first branch 1102, a third branch 1103, a third valve 1104, a fourth valve 1105, and a fifth valve 1106.

[0131] In some embodiments, one end of the second branch 1101 is connected to the second replenishment line, and the other end is connected to the evaporator 103.

[0132] In some embodiments, one end of the first branch 1102 is connected to the top of the gas-liquid separator 602, and the other end is connected to the evaporator 103.

[0133] In some embodiments, one end of the third branch 1103 is connected to the top of the gas-liquid separator 602, and the other end is connected to the economizer 105.

[0134] In some embodiments, a third valve 1104 is disposed on the second branch 1101 for controlling the opening and closing of the second branch 1101.

[0135] In some embodiments, a fourth valve 1105 is disposed on the first branch 1102 for controlling the opening and closing of the first branch 1102.

[0136] In some embodiments, the fifth valve 1106 is disposed on the third branch 1103 and is used to control the opening and closing of the third branch 1103.

[0137] In some embodiments, when the chiller unit 100 is operating under a low compression ratio, the controller 106 can control the first valve 603 to open and the third valve 1104 to close, so that the liquid refrigerant in the condenser 102 flows together with the gaseous refrigerant discharged from the exhaust port of the compressor 101 into the gas-liquid separator 602 under the ejection action of the ejector 601.

[0138] If, after a set time period, the inverter temperature still has not decreased below the safety threshold, the first valve 603 is closed and the third valve 1104 is opened. This allows the refrigerant in the evaporator 103 to flow together with the gaseous refrigerant discharged from the compressor 101's exhaust port into the gas-liquid separator 602, under the ejector action of the ejector 601. Because the refrigerant in the evaporator 103 is at a lower temperature, cooling the inverter with a lower-temperature refrigerant achieves a better cooling effect.

[0139] If the inverter temperature still does not drop below the safety threshold after the set time has elapsed, the fourth valve 1105 is closed and the fifth valve 1106 is opened, so that the return gas of the gas-liquid separator 602 is changed from the evaporator 103 to the economizer 105, thereby increasing the pressure in the gas-liquid separator 602 and thus increasing the amount of refrigerant flowing from the gas-liquid separator 602 to the inverter cooling inlet main line 401, thereby improving the cooling effect of the inverter.

[0140] In some embodiments, the controller 106 can also control the third valve 1104 to open and the first valve 603 to close when there is insufficient refrigerant in the condenser 102. This allows the refrigerant in the evaporator 103 to flow together with the gaseous refrigerant discharged from the compressor 101's exhaust port into the gas-liquid separator 602 under the ejector action of the ejector 601, and then flow to the inverter cooling inlet main line 401. In this way, it can be ensured that the inverter cooling inlet main line 401 receives sufficient refrigerant regardless of whether there is enough refrigerant in the condenser 102, so as to ensure that the inverter receives proper cooling and avoid the inverter from overheating due to failure to receive timely and continuous cooling, which could lead to malfunction.

[0141] In some embodiments, to prevent the inverter from overcooling, such as Figure 12 As shown, the chiller unit provided in the exemplary embodiment of this application may further include a sixth valve 1201.

[0142] In some embodiments, a sixth valve 1201 is provided on the main inlet 402 of the inverter cooling outlet. The sixth valve 1201 is used to prevent the inverter from being overcooled, so as to avoid condensation problems caused by the inverter being too cold.

[0143] Optionally, the sixth valve 1201 can be an electric valve.

[0144] In some embodiments, if the temperature of the frequency converter is detected to be lower than the low temperature warning value, the controller 106 may control the sixth valve 1201 to close to stop cooling the frequency converter, thereby causing the temperature of the frequency converter to rise.

[0145] If the temperature of the frequency converter rises above the low temperature threshold, the controller 106 can control the sixth valve 1201 to open in order to continue cooling the frequency converter.

[0146] In some embodiments, in order to improve the cooling effect of the frequency converter, such as Figure 13 As shown, the chiller unit provided in the exemplary embodiment of this application may further include a seventh valve 1301 and an eighth valve 1302.

[0147] Optionally, the seventh valve 1301 can be an electronic expansion valve, and the eighth valve 1302 can be an electric shut-off valve.

[0148] In some embodiments, when the chiller unit includes a seventh valve 1301 and an eighth valve 1302, the bypass line 901 of the chiller unit 100 can be eliminated. The following describes the chiller unit 100 in detail using the elimination of the bypass line 901 as an example.

[0149] In some embodiments, the seventh valve 1301 is located at the outlet of the frequency conversion cooling pipeline, that is, on the frequency conversion cooling outlet main pipeline 402.

[0150] In some embodiments, the eighth valve 1302 and the seventh valve 1301 are arranged in parallel.

[0151] In some embodiments, in order to cool the frequency converter more precisely under complex operating conditions, such as high ambient humidity and low ambient temperature, the eighth valve 1302 may also be a thermal expansion valve.

[0152] In some embodiments, the controller 106 can control the pressure of the variable frequency cooling outlet main line 402 by controlling the opening degree of the seventh valve 1301, thereby controlling the evaporation temperature of the refrigerant and, consequently, the temperature of the frequency converter.

[0153] For example, the controller 106 can increase the opening of the seventh valve 1301, thereby increasing the flow area of ​​the variable frequency cooling outlet main line 402, reducing the pressure loss of the refrigerant in the variable frequency cooling outlet main line 402, increasing the flow rate of the refrigerant through the variable frequency cooling outlet main line 402 per unit time, and reducing the pressure of the variable frequency cooling outlet main line 402, thereby reducing the evaporation temperature of the refrigerant and thus better cooling the frequency converter.

[0154] The controller 106 can also reduce the opening of the seventh valve 1301, thereby reducing the flow area of ​​the main variable frequency cooling outlet 402, increasing the pressure loss of the refrigerant in the main variable frequency cooling outlet 402, decreasing the refrigerant flow rate through the main variable frequency cooling outlet 402 per unit time, and increasing the pressure in the main variable frequency cooling outlet 402, thus raising the evaporation temperature of the refrigerant. Since the temperature of the frequency converter cannot be lower than the evaporation temperature of the refrigerant used to cool the frequency converter, the possibility of condensation on the frequency converter can be avoided by controlling the evaporation temperature of the refrigerant.

[0155] In some embodiments, one of the main risks of condensation on the inverter is that hot air rises inside the inverter cabinet and condenses upon encountering the low temperature of the sheet metal at the top of the cabinet. This condensation can drip onto electronic components, causing short circuits and malfunctions. To address this issue, the inverter cabinet 303 provided in the exemplary embodiment of this application may include an insulation layer disposed at the top of the mounting space inside the inverter cabinet 303, thereby reducing condensation of hot air at low temperatures. Additionally, the insulation layer provides thermal insulation, slowing down the rate of temperature decrease and maintaining the temperature inside the inverter cabinet 303 within a relatively stable range, further reducing the likelihood of condensation. This effectively protects electronic components from short circuits caused by condensation dripping, ensuring the normal operation of the inverter.

[0156] In some embodiments, exemplary embodiments of this application also provide a structural schematic diagram of a frequency converter cabinet. For example... Figure 14As shown, the frequency converter cabinet 303 may include a water inlet pipe 1401, and the top of the installation space inside the frequency converter cabinet 303 has a four-sided convex downward structure formed by the four sides protruding towards the center.

[0157] In some embodiments, one end of the water inlet pipe 1401 is connected to the vertex of the inverted quadrangular pyramid structure. The condensate generated after condensation can be transported to the outside of the frequency converter cabinet through the water inlet pipe 1401 to prevent condensate from dripping onto electronic components and causing short circuit faults.

[0158] The embodiments provided in this application will now be described in detail with reference to the accompanying drawings.

[0159] like Figure 15 As shown in the figure, this application provides a control method for a chiller unit, which includes the following steps:

[0160] S1501, the controller acquires the compression ratio and cooling parameters of the chiller unit.

[0161] Among them, the cooling parameters are used to characterize the cooling effect of the frequency converter.

[0162] It is understandable that the compression ratio of the chiller unit may affect the amount of refrigerant in the inverter cooling pipes, thereby affecting the cooling effect of the inverter. Therefore, the compression ratio and cooling parameters of the chiller unit can be obtained to determine whether the cooling effect of the inverter is poor, and further, it can be determined whether the control method of the chiller unit provided in the embodiments of this application needs to be implemented to improve the cooling effect of the inverter.

[0163] In some embodiments, cooling parameters may include at least one of the following: changes in the amount of refrigerant in the variable frequency cooling pipeline and the temperature of the variable frequency drive.

[0164] In some embodiments, the controller can detect the amount of refrigerant in the variable frequency cooling pipe through a flow detection device, or it can determine the amount of refrigerant in the variable frequency cooling pipe by detecting parameters such as pressure and temperature at both ends of the variable frequency cooling pipe.

[0165] Furthermore, the controller can determine the change in refrigerant quantity by calculating the difference between the refrigerant quantities in the variable frequency cooling pipe at different times.

[0166] For example, if the amount of refrigerant in the inverter cooling pipe is 1 kg at the first moment, and the amount of refrigerant decreases to 0.5 kg at the second moment, the difference between the amount of refrigerant in the inverter cooling pipe at the first and second moments can be used to determine the change in the amount of refrigerant during the time interval between the first and second moments, which represents the decrease in the amount of refrigerant.

[0167] In some embodiments, the controller can detect the temperature of the inverter via a temperature sensor located on the inverter.

[0168] This application embodiment does not specifically limit the detection method of the amount of refrigerant in the variable frequency cooling pipeline and the temperature of the frequency converter within the first preset time period.

[0169] S1502. When the compression ratio is less than or equal to the first compression ratio threshold and the cooling parameters do not meet the preset cooling index, the controller will transport the refrigerant in the refrigerant circulation loop to the variable frequency cooling pipeline through the gas-liquid separator.

[0170] The preset cooling target refers to the desired cooling effect required by the chiller unit. The preset cooling target can be a temperature range, pressure range, or other relevant parameters, used to ensure that the chiller unit can achieve the required cooling effect under different operating conditions. For example, in a chiller unit, the preset cooling target requires the inverter temperature to be maintained within a set temperature range.

[0171] Understandably, if the compression ratio of the chiller unit is less than or equal to the first compression ratio threshold, it indicates that the compression ratio of the chiller unit is low. In this case, the amount of refrigerant in the inverter cooling pipes may be insufficient, the temperature of the inverter may rise, and the cooling effect of the inverter may be poor. Therefore, it is necessary to further determine whether the cooling parameters meet the preset cooling targets to ascertain whether the cooling effect of the inverter meets the target cooling effect required by the chiller unit, that is, to determine whether the cooling effect of the inverter is poor. Furthermore, it can be determined whether the control method for the chiller unit provided in the embodiments of this application needs to be implemented to improve the cooling effect of the inverter.

[0172] In some embodiments, the cooling parameters failing to meet the preset cooling index includes any of the following: the change is a change that indicates a decrease in the amount of refrigerant in the frequency converter cooling pipeline; the temperature of the frequency converter is greater than or equal to a first temperature threshold.

[0173] Understandably, if the amount of refrigerant decreases within the first preset time period, it indicates that the refrigerant in the inverter cooling pipes is gradually decreasing, leading to a lack of refrigerant and thus gradually reducing the inverter's cooling effect. Therefore, it is necessary to increase the amount of refrigerant in the inverter cooling pipes to improve the inverter's cooling effect.

[0174] If the inverter's temperature is greater than or equal to the first temperature threshold, it indicates that the inverter's temperature is high and its cooling effect is poor. Therefore, the cooling effect of the inverter can be improved by increasing the amount of refrigerant in the inverter's cooling pipes, thereby reducing the inverter's temperature as quickly as possible.

[0175] In some embodiments, when the compression ratio is less than or equal to a first compression ratio threshold and the cooling parameters do not meet the preset cooling index, the controller delivers the refrigerant in the refrigerant circulation pipeline to the frequency converter cooling pipeline through a gas-liquid separator, which can replenish the amount of refrigerant cooling the frequency converter and improve the cooling effect of the frequency converter.

[0176] For example, the condenser and compressor can be connected to the variable frequency cooling system via a replenishment line. The controller can open the replenishment line by controlling a valve on the replenishment line, allowing the refrigerant in the compressor and condenser in the refrigerant circulation line to be delivered to the variable frequency cooling system via the gas-liquid separator. Furthermore, the specific procedure for controlling the valve on the replenishment line can be found below. Figure 16 The specific descriptions of the embodiments shown are not repeated here.

[0177] In some embodiments, when the ambient humidity is greater than or equal to a humidity threshold, the ambient temperature is greater than or equal to a second temperature threshold, and the cooling parameters do not meet the preset cooling index, the controller can also deliver the refrigerant in the refrigerant circulation loop to the frequency converter cooling pipeline through a gas-liquid separator.

[0178] Understandably, in environments with high temperature and humidity, the amount of refrigerant in the inverter cooling pipes may be insufficient, potentially leading to a rise in inverter temperature and poor cooling performance. Therefore, increasing the amount of refrigerant in the inverter cooling pipes can improve cooling efficiency and lower inverter temperature more quickly.

[0179] Furthermore, regarding the specific process of increasing the amount of refrigerant in the variable frequency cooling pipeline when the ambient humidity is greater than or equal to the humidity threshold, the ambient temperature is greater than or equal to the second temperature threshold, and the cooling parameters do not reach the preset cooling index, please refer to the above-described specific description of increasing the amount of refrigerant in the variable frequency cooling pipeline when the compression ratio is less than or equal to the first compression ratio threshold and the cooling parameters do not reach the preset cooling index. This application will not elaborate further here.

[0180] S1503: When the compression ratio is greater than or equal to the second compression ratio threshold, the controller will deliver the refrigerant in the variable frequency cooling pipeline to the evaporator through the bypass pipeline.

[0181] The amount of refrigerant delivered to the evaporator through the bypass pipeline is less than the total amount of refrigerant in the variable frequency cooling pipeline.

[0182] Understandably, if the compression ratio of a chiller unit is greater than or equal to the second compression ratio threshold, it indicates that the chiller unit has a high compression ratio. A high compression ratio in a chiller unit will increase the amount of refrigerant in the inverter's cooling pipes, which may lead to over-cooling of the inverter, resulting in excessively low temperatures and condensation. Once condensation occurs on the inverter, it can easily cause short circuits or even burn out the inverter. To solve this problem, the amount of refrigerant in the inverter's cooling pipes can be reduced.

[0183] In some embodiments, the controller can deliver refrigerant from the variable frequency cooling pipe to the evaporator via a bypass pipe, so that a portion of the refrigerant originally flowing into the variable frequency cooling pipe flows to the evaporator via the bypass pipe, thereby maintaining the amount of refrigerant in the variable frequency cooling pipe within a suitable range.

[0184] For example, an unloading valve is installed on the bypass pipeline. When the compression ratio is greater than or equal to a second compression ratio threshold, the controller can open the unloading valve to open the bypass pipeline, allowing a portion of the refrigerant in the variable frequency cooling pipeline to be transported to the evaporator through the bypass pipeline. That is, the amount of refrigerant transported to the evaporator through the bypass pipeline is less than the total amount of refrigerant in the variable frequency cooling pipeline.

[0185] In addition, the specific procedure for controlling the opening of the unloading valve can be found below. Figure 18 The specific descriptions of the embodiments shown are not repeated here.

[0186] based on Figure 15 The embodiments shown in this application provide a control method for a chiller unit according to exemplary embodiments. When the compression ratio of the chiller unit is less than or equal to a first compression ratio threshold (i.e., when the compression ratio of the chiller unit is low), liquid refrigerant in the refrigerant circulation loop is supplemented into the variable frequency cooling pipeline through a gas-liquid separator to improve the cooling effect of the variable frequency drive. Alternatively, when the compression ratio of the chiller unit is greater than or equal to a second compression ratio threshold (i.e., when the compression ratio of the chiller unit is high), refrigerant can be allowed to flow out through a bypass pipeline. This allows a portion of the refrigerant originally flowing into the variable frequency cooling pipeline to flow to the evaporator through the bypass pipeline, maintaining the amount of refrigerant in the variable frequency cooling pipeline within a suitable range. This avoids over-cooling the variable frequency drive, preventing excessively low inverter temperature and condensation, thus improving the cooling effect.

[0187] In this way, this control method can not only effectively meet the cooling needs of the chiller unit under various complex operating conditions, but also achieve better cooling effect under different operating conditions.

[0188] In some embodiments, such as Figure 16 As shown, step S1502 can be implemented as follows.

[0189] S1601, The controller controls the first valve to open, so as to deliver the refrigerant in the condenser and the refrigerant discharged from the compressor outlet to the gas-liquid separator through the ejector.

[0190] The amount of refrigerant discharged from the compressor's exhaust port is less than the total amount of refrigerant in the compressor.

[0191] Optionally, the amount of refrigerant delivered from the condenser to the gas-liquid separator can be less than the total amount of refrigerant in the condenser.

[0192] For example, based on Figure 6 or Figure 8 The chiller unit shown has a controller that can open the first valve, allowing the liquid refrigerant in the condenser to flow together with the gaseous refrigerant discharged from the compressor's exhaust port into the gas-liquid separator under the ejector action of the ejector.

[0193] In addition, the gaseous refrigerant in the gas-liquid separator flows to the evaporator, and under the action of the throttling device, the pressure of the gas-liquid separator is higher than the pressure of the main circuit of the variable frequency cooling inlet.

[0194] In some embodiments, the controller can detect the liquid level in the condenser using a liquid level detection device on the condenser before controlling the opening of the first valve. Further, the first valve is only opened if the liquid level in the condenser is greater than a first preset threshold, i.e., if it is determined that there is sufficient refrigerant in the condenser.

[0195] When the liquid level in the condenser is less than or equal to the first preset threshold, that is, when it is determined that the refrigerant in the condenser is insufficient, part of the refrigerant in the compressor and evaporator in the refrigerant circulation pipeline is transported to the gas-liquid separator.

[0196] For example, the specific process of delivering refrigerant from the compressor and evaporator in the refrigerant circulation line to the gas-liquid separator can be referred to as follows. Figure 17 The specific descriptions of the embodiments shown are not repeated here.

[0197] S1602. When the liquid level detected by the liquid level detection device is greater than or equal to the first height threshold, the controller controls the second valve to open, so that the refrigerant in the gas-liquid separator flows to the frequency conversion cooling pipeline.

[0198] For example, based on Figure 8 The chiller unit shown can, after the controller opens the first valve, open the second valve when the liquid level detection device detects that the liquid level has reached the first height threshold. This allows the liquid refrigerant from the gas-liquid separator to be replenished into the main inlet of the frequency converter under the pressure difference between the gas-liquid separator and the main inlet of the frequency converter, thereby supplementing the amount of refrigerant for cooling the frequency converter and improving the cooling effect of the frequency converter.

[0199] For example, based on Figure 6 The chiller unit shown can also control the second valve to open after the first valve has been open for a set duration.

[0200] Understandably, after the first valve opens, refrigerant from the condenser and compressor will continuously enter the gas-liquid separator. After the first valve remains open for a set duration, the refrigerant in the gas-liquid separator will reach a certain height. When the level detection device detects that the level has reached a first threshold, the controller then opens the second valve. This allows the liquid refrigerant in the gas-liquid separator to replenish the main cooling inlet of the inverter under the pressure difference between the gas-liquid separator and the main cooling inlet, thus increasing the amount of refrigerant cooling the inverter and improving its cooling effect.

[0201] In some embodiments, such as Figure 17 As shown, step S1502 can also be implemented as follows.

[0202] S1701, The controller detects the liquid level in the condenser.

[0203] In some embodiments, the controller can detect the liquid level in the condenser using a liquid level detection device on the condenser.

[0204] S1702. When the controller detects that the liquid level in the condenser is less than or equal to the second height threshold, it controls the third valve to open so that the refrigerant in the evaporator and the refrigerant discharged from the compressor outlet can be transported to the variable frequency cooling pipeline through the second branch.

[0205] The amount of refrigerant discharged from the compressor's exhaust port is less than the total amount of refrigerant in the compressor.

[0206] Understandably, if the liquid level in the condenser is less than or equal to the first preset threshold, it indicates that the refrigerant in the condenser is insufficient. Since the amount of refrigerant in the chiller unit is constant, if there is less refrigerant in the condenser and more refrigerant in the evaporator, the refrigerant in the evaporator and the refrigerant in the compressor can be transported to the variable frequency cooling pipeline through the second branch by controlling the third valve.

[0207] For example, based on Figure 11The chiller unit shown, when the refrigerant in the condenser is insufficient, controls the opening of the third valve and the closing of the first valve. This allows the refrigerant in the evaporator to flow together with the gaseous refrigerant discharged from the compressor's exhaust port into the gas-liquid separator under the ejector's action, and then into the main inlet circuit of the inverter cooling system. In this way, it is ensured that the main inlet circuit of the inverter cooling system receives sufficient refrigerant regardless of whether the condenser has enough, guaranteeing proper cooling of the inverter and preventing it from overheating due to insufficient and untimely cooling, which could lead to malfunctions.

[0208] In some embodiments, such as Figure 18 As shown, step S1503 can be implemented as follows.

[0209] S1801. When the temperature of the frequency converter is less than or equal to the third temperature threshold, the controller adjusts the opening of the unloading valve so that the refrigerant in the refrigerant circulation loop is delivered to the evaporator through the bypass pipeline.

[0210] It is understandable that by adjusting the opening of the unloading valve, the refrigerant in the refrigerant circulation loop can flow out through the bypass pipe, thereby maintaining the amount of refrigerant in the variable frequency cooling pipe within a suitable range.

[0211] In one example, when there are multiple first bypass lines and the unloading valve is an electric valve, the controller can adjust the opening degree of the unloading valve based on the temperature of the frequency converter.

[0212] For example, the chiller unit is equipped with three bypass circuits and three unloading valves. The bypass circuits are bypass line 1, bypass line 2 and bypass line 3, and the unloading valves are unloading valve 1, unloading valve 2 and unloading valve 3.

[0213] In situations where the ambient temperature is low and the ambient humidity is high, if the inverter temperature is less than or equal to the third temperature threshold, which is the low temperature warning value, it indicates that the cooling is excessive and the No. 1 unloading valve needs to be opened. That is, the opening degree of the unloading valve is adjusted from zero to a greater than zero, so that the refrigerant can flow out through the No. 1 bypass pipe.

[0214] If the compression ratio of the chiller unit continues to rise, and the inverter temperature still does not rise but exceeds the low-temperature warning value, then it is necessary to open unloading valve No. 2 to allow refrigerant to flow out through bypass pipe No. 2, further bypassing some refrigerant. This process continues until the inverter temperature is within a suitable range, or all unloading valves are open.

[0215] Conversely, if the inverter temperature reaches the high temperature warning value, the unloading valves will be closed sequentially, that is, the opening degree of the unloading valves will be adjusted to 0, until the inverter temperature is within a suitable temperature range, or all unloading valves are closed.

[0216] In another example, where there are multiple first bypass lines and the unloading valves are electronic expansion valves, the controller can adjust the opening degree of multiple unloading valves based on the temperature of the frequency converter.

[0217] Furthermore, the specific procedure for adjusting the opening degree of the unloading valve based on the inverter temperature can be found in the above example where the unloading valve is an electric valve, and the specific description of adjusting the opening degree of the unloading valve based on the inverter temperature will not be repeated here.

[0218] In some embodiments, the unloading valve may also be a mechanical pressure relief valve. When the unloading valve is a mechanical pressure relief valve, if the pressure difference between the outlet of the variable frequency cooling pipeline and the inlet of the variable frequency cooling pipeline is greater than the preset opening pressure of the unloading valve, the unloading valve is in the open state.

[0219] For example, when there are multiple first bypass lines and the unloading valve is a mechanical pressure relief valve, the controller can control any one or more unloading valves to open when the pressure difference is greater than the preset opening pressure of any one or more of the multiple unloading valves.

[0220] For example, the chiller unit is equipped with three bypass circuits and three unloading valves. The bypass circuits are bypass line 1, bypass line 2, and bypass line 3, and the unloading valves are unloading valve 1, unloading valve 2, and unloading valve 3. The opening pressure of unloading valve 1 is lower than that of unloading valve 2, and the opening pressure of unloading valve 2 is lower than that of unloading valve 3.

[0221] If the pressure difference detected by the chiller unit between the outlet and inlet of the variable frequency cooling pipe is greater than the opening pressure of the No. 1 unloading valve, then the No. 1 unloading valve will be opened so that the refrigerant can flow out through the No. 1 bypass pipe.

[0222] If the pressure difference between the outlet and inlet of the variable frequency cooling pipe continues to increase, and if the pressure difference between the outlet and inlet of the variable frequency cooling pipe is detected to be greater than the opening pressure of the No. 2 unloading valve, the No. 2 unloading valve will be opened after the No. 1 unloading valve has been opened, so that the refrigerant can still flow out through the No. 2 bypass pipe.

[0223] If the pressure difference between the outlet and inlet of the variable frequency cooling pipe continues to increase, and if the pressure difference exceeds the opening pressure of unloading valve #3, then unloading valve #3 will be opened, allowing refrigerant to continue flowing through bypass pipe #3, provided unloading valves #1 and #2 are already open. This process continues until the pressure difference between the outlet and inlet of the variable frequency cooling pipe reaches the upper limit of the rated pressure difference, or all unloading valves are opened.

[0224] In some embodiments, to further improve the cooling effect, such as Figure 19 As shown in the exemplary embodiment of this application, the control method for a chiller unit may further include the following steps.

[0225] S1901. After the controller controls the first valve to open and the second valve to open for a first preset time, when it detects that the temperature of the frequency converter is greater than or equal to the first temperature threshold, it controls the first valve to close and the third valve to open, so that the refrigerant in the evaporator enters the frequency converter cooling pipeline through the second branch.

[0226] Understandably, if the inverter's temperature remains above or equal to a first temperature threshold after the first and second valves have been open for a first preset time, the current cooling effect is considered average. To further improve the cooling effect, the first valve can be closed and the third valve opened, allowing the cooler refrigerant in the evaporator to enter the inverter's cooling pipes through the second branch. Since the refrigerant in the evaporator is at a lower temperature, cooling the inverter with this cooler refrigerant achieves a better cooling effect.

[0227] For example, based on Figure 11 The chiller unit shown can be controlled by the controller to keep the second valve open for a first preset time. If the temperature of the frequency converter still does not drop below the first temperature threshold, the controller will close the first valve and open the third valve, so that the refrigerant in the evaporator flows together with the gaseous refrigerant discharged from the compressor outlet into the gas-liquid separator under the ejection action of the ejector.

[0228] S1902. After the controller controls the first valve to close and the third valve to open for a second preset time, if the temperature of the frequency converter is detected to be greater than or equal to the first temperature threshold, the controller controls the fifth valve to open and the fourth valve to close, so as to connect the return port of the gas-liquid separator to the economizer.

[0229] Understandably, after the first valve is closed and the third valve is open for a second preset time, if the temperature of the inverter is still not below the first temperature threshold, the fifth valve is opened to change the component connected to the return port of the gas-liquid separator from the evaporator to the economizer, thereby increasing the pressure in the gas-liquid separator and thus increasing the amount of refrigerant input from the gas-liquid separator to the inverter cooling pipe, thereby improving the cooling effect of the inverter.

[0230] Furthermore, through coordination with step S1901, multiple adjustments can be achieved, and the cooling effect can be gradually improved, avoiding the possibility of overcooling and condensation or undercooling and overheating of the inverter that may occur with a one-size-fits-all liquid replenishment scheme.

[0231] The following is an exemplary description Figure 19 The complete flow of the control method for the chiller unit in the illustrated embodiment.

[0232] like Figure 20 As shown, the process begins.

[0233] Step a1: Determine whether the liquid level in the condenser is greater than the second height threshold.

[0234] If so, proceed to step a2 below.

[0235] If not, proceed to step a7 below.

[0236] Step a2: Control the first valve to open and the second valve to open.

[0237] Determine whether to continue for the first preset duration.

[0238] If so, proceed to step a3 below.

[0239] If not, proceed to step a2.

[0240] Step a3: Determine whether the temperature of the frequency converter is greater than or equal to the first temperature threshold.

[0241] If so, proceed to step a4 below.

[0242] If not, the process ends.

[0243] Step a4: Control the first valve to close and the third valve to open.

[0244] Determine whether to continue for the second preset duration.

[0245] If so, proceed to step a5 below.

[0246] If not, proceed to step a4.

[0247] Step a5: Determine if the temperature of the frequency converter is greater than or equal to the first temperature threshold.

[0248] If so, proceed to step a6 below.

[0249] If not, the process ends.

[0250] Step a6: Control the fifth valve to open and the fourth valve to close.

[0251] Step a7: Control the third valve to open and the second valve to open.

[0252] In some embodiments, the control method for a chiller unit provided in this application may further include the following steps.

[0253] S2101. When the temperature of the frequency converter is detected to be greater than or equal to the second temperature threshold, the opening degree of the seventh valve is increased.

[0254] Understandably, the controller can increase the opening of the seventh valve, thereby increasing the flow area of ​​the main variable frequency cooling outlet circuit, reducing the pressure loss of the refrigerant in the main variable frequency cooling outlet circuit, increasing the flow rate of the refrigerant through the main variable frequency cooling outlet circuit per unit time, and reducing the pressure of the main variable frequency cooling outlet circuit 402, thus lowering the temperature of the evaporator and thus better cooling the variable frequency drive.

[0255] S2102. When the temperature of the frequency converter is detected to be less than or equal to the second temperature threshold, the opening degree of the seventh valve is reduced.

[0256] Understandably, the controller can also reduce the opening of the seventh valve, thereby reducing the flow area of ​​the main variable frequency cooling outlet circuit, increasing the pressure loss of the refrigerant in the main circuit, decreasing the refrigerant flow rate per unit time, and increasing the pressure in the main circuit, thus raising the evaporator temperature. Since the inverter temperature cannot be lower than the evaporation temperature of the refrigerant used to cool it, the possibility of condensation on the inverter can be avoided by controlling the evaporator temperature.

[0257] S2103. When the ambient humidity is greater than or equal to the humidity threshold, the ambient temperature is greater than or equal to the temperature threshold, the opening degree of the seventh valve is equal to the upper limit of the rated opening degree of the seventh valve, and the temperature of the frequency converter is greater than or equal to the temperature threshold, control the eighth valve to open.

[0258] Understandably, when the seventh valve is fully open but the inverter temperature still exceeds the high temperature warning value, the eighth valve is opened to increase the flow area of ​​the inverter cooling outlet and reduce pressure loss. At the same time, it can be directly connected to the evaporator to reduce the evaporation temperature of the refrigerant in the inverter cooling heat exchanger, so that the inverter temperature can drop rapidly.

[0259] Those skilled in the art will recognize that, in one or more of the examples above, the functions described in this invention can be implemented using hardware, software, firmware, or any combination thereof. When implemented in software, these functions can be stored in a computer-readable medium or transmitted as one or more instructions or code on a computer-readable medium. Computer-readable media include computer storage media and communication media, wherein communication media include any medium that facilitates the transfer of a computer program from one place to another. Storage media can be any available medium accessible to a general-purpose or special-purpose computer.

[0260] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A water chiller unit, characterized in that, include: The refrigerant circulation loop includes the compressor, condenser, throttling device, and evaporator; Frequency converter; The variable frequency cooling pipeline is connected at one end to the condenser and at the other end to the evaporator; Gas-liquid separator; A bypass pipeline is provided in parallel with the variable frequency cooling pipeline, with one end connected to the outlet pipeline of the variable frequency cooling pipeline and the other end connected to the inlet pipeline of the variable frequency cooling pipeline. The controller is configured as follows: The compression ratio and cooling parameters of the chiller unit are obtained; the cooling parameters are used to characterize the cooling effect of the frequency converter. When the compression ratio is less than or equal to the first compression ratio threshold and the cooling parameters do not reach the preset cooling index, the refrigerant in the refrigerant circulation loop is transported to the variable frequency cooling pipeline through the gas-liquid separator. When the compression ratio is greater than or equal to the second compression ratio threshold, the refrigerant in the variable frequency cooling pipeline is transported to the evaporator through the bypass pipeline; wherein the amount of refrigerant transported to the evaporator through the bypass pipeline is less than the total amount of refrigerant in the variable frequency cooling pipeline.

2. The chiller unit according to claim 1, characterized in that, The chiller unit also includes: A cooling device is installed on the frequency converter cooling pipeline to cool the frequency converter; A liquid level detection device is installed on the gas-liquid separator to detect the liquid level height of the gas-liquid separator; The ejector is connected to the exhaust port of the compressor via a first replenishment line, to the bottom of the condenser via a second replenishment line, and to the gas-liquid separator via a third replenishment line. One end of the liquid supply pipeline is connected to the bottom of the gas-liquid separator, and the other end is connected to the frequency conversion cooling pipeline; The first branch has one end connected to the top of the gas-liquid separator and the other end connected to the evaporator; The first valve is installed on the second replenishment pipeline; The second valve is installed on the liquid supply pipeline; The controller is configured to deliver refrigerant in the refrigerant circulation loop to the variable frequency cooling pipeline via the gas-liquid separator, including: The first valve is controlled to open so that the refrigerant in the condenser and the refrigerant discharged from the compressor outlet are conveyed to the gas-liquid separator through the ejector; wherein the amount of refrigerant discharged from the compressor outlet is less than the total amount of refrigerant in the compressor; If the liquid level detected by the liquid level detection device is greater than or equal to the first height threshold, the second valve is controlled to open, so that the refrigerant in the gas-liquid separator flows to the frequency conversion cooling pipeline.

3. The chiller unit according to claim 1, characterized in that, The chiller unit also includes: The second branch has one end connected to the second replenishment pipeline and the other end connected to the evaporator; The third valve is installed on the second branch and is used to control the opening and closing of the second branch; The controller is configured to deliver refrigerant in the refrigerant circulation loop to the variable frequency cooling pipeline via the gas-liquid separator, including: Detect the liquid level in the condenser; If the liquid level in the condenser is detected to be less than or equal to a second height threshold, the third valve is controlled to open so that the refrigerant in the evaporator and the refrigerant discharged from the compressor's exhaust port are transported to the variable frequency cooling pipeline through the second branch; wherein the amount of refrigerant discharged from the compressor's exhaust port is less than the total amount of refrigerant in the compressor.

4. The chiller unit according to claim 1, characterized in that, The cooling parameters include at least one of the following: the change in the amount of refrigerant in the variable frequency cooling pipeline and the temperature of the variable frequency drive; The cooling parameters failing to meet the preset cooling targets include any of the following: the change is a change used to indicate the decrease in the amount of refrigerant in the variable frequency cooling pipeline; The temperature of the frequency converter is greater than or equal to a first temperature threshold.

5. The chiller unit according to claim 1, characterized in that, The chiller unit also includes: An unloading valve, disposed on the bypass pipeline, is used to control the opening and closing of the bypass pipeline; the controller, configured to deliver refrigerant in the refrigerant circulation loop to the evaporator through the bypass pipeline, includes: When the temperature of the frequency converter is less than or equal to the third temperature threshold, the opening of the unloading valve is adjusted so that the refrigerant in the refrigerant circulation loop is delivered to the evaporator through the bypass pipeline.

6. The chiller unit according to claim 1, characterized in that, The controller is also configured to: When the ambient humidity is greater than or equal to the humidity threshold, the ambient temperature is greater than or equal to the second temperature threshold, and the cooling parameters do not reach the preset cooling index, the refrigerant in the refrigerant circulation loop is transported to the variable frequency cooling pipeline through the gas-liquid separator.

7. The chiller unit according to claim 2, characterized in that, The chiller unit also includes: Economic instruments; The second branch is connected at one end to the second replenishment pipeline and at the other end to the evaporator; the third branch is connected at one end to the top of the gas-liquid separator and at the other end to the economizer. The third valve is installed on the second branch and is used to control the opening and closing of the second branch; The fourth valve is located on the first branch. The fifth valve is located on the third branch. The controller is also configured to: After the first valve and the second valve are kept open for a first preset time, if the temperature of the inverter is detected to be greater than or equal to a first temperature threshold, the first valve is closed and the third valve is opened, so that the refrigerant in the evaporator enters the inverter cooling pipeline through the second branch. After controlling the first valve to close and the third valve to open for a second preset time, if the temperature of the frequency converter is detected to be greater than or equal to the first temperature threshold, the fifth valve is controlled to open and the fourth valve is controlled to close, so as to connect the return port of the gas-liquid separator to the economizer.

8. The chiller unit according to any one of claims 1-7, characterized in that, The chiller unit also includes: The sixth valve is located at the outlet of the variable frequency cooling pipeline; The controller is also configured to: If the temperature of the frequency converter is detected to be less than or equal to the third temperature threshold, the sixth valve is controlled to close to stop cooling the frequency converter.

9. The chiller unit according to claim 1, characterized in that, The chiller unit also includes: The seventh valve is located at the outlet of the variable frequency cooling pipeline; The eighth valve is connected in parallel with the seventh valve; The controller is also configured to: If the temperature of the frequency converter is detected to be greater than or equal to the first temperature threshold, the opening degree of the seventh valve is controlled to increase. If the temperature of the frequency converter is detected to be less than or equal to the third temperature threshold, the opening of the seventh valve is controlled to decrease. When the ambient humidity is greater than or equal to the humidity threshold, the ambient temperature is greater than or equal to the second temperature threshold, the opening degree of the seventh valve is equal to the upper limit of the rated opening degree of the seventh valve, and the temperature of the frequency converter is greater than or equal to the first temperature threshold, the eighth valve is controlled to open.

10. A control method for a chiller unit, characterized in that, include: The compression ratio and cooling parameters of the chiller unit are obtained; the cooling parameters are used to characterize the cooling effect of the frequency converter. When the compression ratio is less than or equal to the first compression ratio threshold and the cooling parameters do not reach the preset cooling index, the refrigerant in the refrigerant circulation loop is transported to the variable frequency cooling pipeline through the gas-liquid separator. When the compression ratio is greater than or equal to the second compression ratio threshold, the refrigerant in the variable frequency cooling pipeline is transported to the evaporator through the bypass pipeline; wherein the amount of refrigerant transported to the evaporator through the bypass pipeline is less than the total amount of refrigerant in the variable frequency cooling pipeline.

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