Air conditioning compressor start-stop control method and system, and air conditioning system

Abstract

The present invention discloses a start-stop control method and system for an air-conditioning compressor, and an air-conditioning system, wherein the method includes a start control method and a stop control method; the stop control method includes: upon receiving a compressor stop command, completely closing the electronic expansion valve in the refrigerant main circuit where the compressor is located; upon confirming that the first pressure on the low-pressure side of the compressor is less than or equal to a first pressure threshold, controlling the compressor to enter a stop state; the start control method includes: upon receiving a compressor start command, upon confirming that the second pressure on the low-pressure side of the compressor is less than or equal to a second pressure threshold, adjusting the opening of the electronic expansion valve to a third set value so that the refrigerant is in a normal circulation state. The above-mentioned control method of the present invention does not require the use of a gas-liquid separator, and ensures that as little refrigerant as possible remains on the low-pressure side during the shutdown process, and ensures that as little refrigerant as possible returns to the compressor during the startup process, thereby reducing the risk of liquid hammer and lubricating oil dilution.

Description

Technical Field

[0001] The present invention relates to the technical field of air conditioning control, and in particular to a method and system for controlling the start and stop of an air conditioning compressor, and an air conditioning system. Background Art

[0002] Air conditioning systems, especially heat pump systems, often face the problem of liquid refrigerant backflowing into the compressor during startup, mode switching, or defrosting. This phenomenon can cause compressor liquid hammer or excessive liquid refrigerant diluting the lubricant, leading to oil leakage or reduced lubrication effectiveness, ultimately shortening the compressor's service life and potentially even damaging it.

[0003] To address this issue, the industry currently typically adds a gas-liquid separator to the compressor suction side. This separator separates and stores the liquid refrigerant on the compressor suction side based on the system's refrigerant charge. This approach alleviates the problem of liquid refrigerant backflow to a certain extent. However, the use of gas-liquid separators also brings new challenges.

[0004] First, to effectively separate and store the liquid refrigerant, the gas-liquid separator must have sufficient capacity and separation efficiency. Consequently, the gas-liquid separator must be designed to be large. This design not only takes up valuable space but also affects the layout of components within the air conditioning system, increasing the complexity of design and installation.

[0005] Secondly, the addition of a gas-liquid separator will cause a certain pressure drop on the compressor's suction side. This increased pressure drop means the compressor must overcome greater resistance to draw in refrigerant, which negatively impacts the unit's performance and energy efficiency. Especially with increasingly stringent energy efficiency requirements, any factor that reduces energy efficiency needs to be seriously addressed and optimized.

[0006] In summary, although adding a gas-liquid separator on the suction side of the compressor solves the problem of liquid refrigerant return, the space occupation and pressure drop problems it brings still need to be further optimized. Summary of the Invention

[0007] The object of the present invention is to provide an air-conditioning compressor start-stop control method, system and air-conditioning system that avoid liquid hammer damage to the compressor caused by liquid refrigerant backflow without using a gas-liquid separator.

[0008] In order to achieve the above object, the present invention provides an air-conditioning compressor start-stop control method, which includes a start control method for controlling the compressor to start and a stop control method for controlling the compressor to stop running;

[0009] The stop control method includes: upon receiving a compressor stop instruction, controlling the compressor to enter a minimum load state and completely closing an electronic expansion valve in a refrigerant main circuit where the compressor is located;

[0010] When confirming that the first pressure on the low-pressure side of the compressor is less than or equal to a first pressure threshold, controlling the compressor to enter a stopped state;

[0011] The startup control method comprises: upon receiving a compressor startup instruction, adjusting the opening of the electronic expansion valve to a first set value, delaying for a first preset time, and then controlling the compressor to start and enter a minimum load state;

[0012] When the compressor runs for a second preset time and it is confirmed that the second pressure on the low-pressure side of the compressor is greater than a second pressure threshold, the opening of the electronic expansion valve is adjusted to a second set value so that the pressure on the low-pressure side of the compressor gradually decreases. Until the second pressure is less than or equal to the second pressure threshold, the opening of the electronic expansion valve is adjusted to a third set value so that the refrigerant is in a normal circulation state, and after a preset delay time, the electronic expansion valve is controlled to enter an automatic adjustment state.

[0013] Preferably, the first setting value is greater than the third setting value, and the third setting value is greater than the second setting value.

[0014] Preferably, in the stop control method, if the duration for which the first pressure is greater than the first pressure threshold is greater than a third preset duration, the compressor is controlled to enter a stop state.

[0015] Preferably, in the startup control method, after the opening of the electronic expansion valve is adjusted to the second set value, if the second pressure is greater than the second pressure threshold for a duration greater than a fourth preset duration, the opening of the electronic expansion valve is reduced, and the second pressure is continuously compared with the second pressure threshold.

[0016] Preferably, in the startup control method, if the duration for which the second pressure is greater than the second pressure threshold is greater than a fifth preset duration, the opening of the electronic expansion valve is adjusted to the third set value.

[0017] The present invention also provides an air-conditioning system, which includes a compressor and a condenser and an evaporator connected to the compressor, wherein the compressor is connected to the condenser through a four-way valve, and the condenser is connected to the evaporator through an electronic expansion valve. The air-conditioning system also includes a controller electrically connected to the compressor and the electronic expansion valve, and the controller controls the start and stop of the compressor based on the air-conditioning compressor start and stop control method as described above.

[0018] Preferably, an economizer is further included, the three pipeline connection ends of the condenser are respectively connected to the evaporator, the condenser and the compressor, and the electronic expansion valve is arranged on the connecting pipeline between the economizer and the evaporator.

[0019] The present invention also provides an air-conditioning compressor start-stop control system, which includes:

[0020] one or more processors;

[0021] Memory;

[0022] and one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, the programs including instructions for executing the air-conditioning compressor start-stop control method as described above.

[0023] The present invention also provides a computer-readable storage medium, which includes a computer program. The computer program can be executed by a processor to implement the air-conditioning compressor start-stop control method as described above.

[0024] Compared with the prior art, the control method provided by the above technical solution of the present invention strictly controls the opening and closing state of the electronic expansion valve during the compressor start-up and shutdown process, thereby controlling the pressure on the low-pressure side of the compressor. This ensures that as little refrigerant as possible remains on the low-pressure side during the shutdown process, and as little refrigerant as possible returns to the compressor during the startup process. This reduces the risk of liquid hammer and lubricating oil dilution, not only protecting the mechanical components of the compressor, but also improving the lubrication effect and extending the service life of the compressor. In addition, compared with the traditional method of adding a gas-liquid separator, this control method saves physical space in the air conditioning system, does not increase the pressure drop on the suction side of the compressor, and has little impact on the system layout and performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 2 is a schematic structural diagram of an air-conditioning system in an embodiment of the present invention.

[0026] Figure 2 This is a flow chart of the stop control method in an embodiment of the present invention.

[0027] Figure 3 This is a flow chart of the startup control method in an embodiment of the present invention. DETAILED DESCRIPTION

[0028] In order to explain the technical content, structural features, achieved objectives and effects of the present invention in detail, the following is a detailed description in conjunction with the embodiments and the accompanying drawings.

[0029] This embodiment discloses a start-stop control method for an air-conditioning compressor, so as to control the operation of the compressor without using a gas-liquid separator, thereby avoiding liquid hammer caused by refrigerant backflow during the start-stop process.

[0030] Liquid floodback during compressor startup refers to the phenomenon or process in which liquid refrigerant or lubricant in the evaporator flows back into the compressor through the suction line while the compressor is running. Liquid floodback negatively impacts the compressor M and, if excessive, can even lead to liquid hammer. Liquid hammer causes vibration, increased noise, and damage to the compressor rotor and bearings. In severe cases, it can damage the equipment and cause accidents.

[0031] In order to facilitate the understanding of the specific scheme of the following control method, the circulation flow of the refrigerant in the compressor is briefly introduced first.

[0032] Inside the compressor, it is divided into high-pressure side and low-pressure side according to the different refrigerant pressures.

[0033] When the compressor is working, the refrigerant is extracted from the low-pressure side, compressed and sent to the high-pressure side for heat dissipation, and then returned to the low-pressure side through components such as the expansion valve, completing the preparation for the refrigeration cycle.

[0034] The control method in this embodiment mainly controls the pressure on the low-pressure side of the compressor to reduce the probability of liquid hammer.

[0035] It should also be noted that, since the control method in this embodiment does not rely on a gas-liquid separator, the air-conditioning system to which the control method is applicable will be described first.

[0036] like Figure 1 The air-conditioning system includes a compressor M and a condenser L and an evaporator F connected to the compressor M, wherein the compressor M is connected to the condenser L through a four-way valve W, and the condenser L is connected to the evaporator F through an electronic expansion valve EXV. The air-conditioning system also includes a controller (not shown) electrically connected to the compressor M and the electronic expansion valve EXV, and the controller controls the operation of the compressor M and the electronic expansion valve EXV.

[0037] On the other hand, the air conditioning system also includes an economizer E, whose three pipe connection ends are respectively connected to the evaporator F, the condenser L and the compressor M, and the electronic expansion valve EXV is arranged on the connecting pipe between the economizer E and the evaporator F.

[0038] Based on this, the control method in this embodiment includes a start control method for controlling the compressor M to start and a stop control method for controlling the compressor M to stop running.

[0039] Stop control methods include:

[0040] When the compressor M shutdown command is received, the compressor M is controlled to enter the minimum load state, and the electronic expansion valve EXV in the refrigerant main circuit where the compressor M is located is completely closed;

[0041] Then, when it is confirmed that the first pressure on the low-pressure side of the compressor M is less than or equal to the first pressure threshold, the compressor M is controlled to enter a stopped state. In other words, the shutdown of the compressor M is delayed. During this process, the refrigerant on the low-pressure side of the compressor M is continuously pumped out until the pressure on the low-pressure side of the compressor M drops to the set value. This ensures that when the compressor M is stopped, as little refrigerant as possible remains on the low-pressure side of the compressor M, effectively reducing the risk of liquid backflow when the compressor M is restarted.

[0042] In addition, in the stop control method, when the compressor M stop command is received, the compressor M is first put into the minimum load state. The purpose of this operation is to reduce the refrigerant flow of the compressor M, prepare for extracting the refrigerant out of the low-pressure side, and reduce energy consumption.

[0043] Completely closing the electronic expansion valve EXV in the refrigerant main circuit can effectively prevent the refrigerant from continuing to flow into the low-pressure side of the compressor M, especially during the shutdown process, to prevent liquid refrigerant from flowing back into the compressor M due to inertia or pressure difference within the system.

[0044] Startup control methods include:

[0045] First, when the compressor M start command is received, the opening of the electronic expansion valve EXV is adjusted to a first set value, and after a delay of a first preset time, the compressor M is controlled to start and enter the minimum load state;

[0046] Then, after the compressor M has run for the second preset time, when it is confirmed that the second pressure on the low-pressure side of the compressor M is greater than the second pressure threshold, the opening of the electronic expansion valve EXV is adjusted to the second set value, so that the pressure on the low-pressure side of the compressor M gradually decreases. Until the second pressure is less than or equal to the second pressure threshold, the opening of the electronic expansion valve EXV is adjusted to the third set value, so that the refrigerant is in a normal circulation state, and after the preset delay time, the electronic expansion valve EXV is controlled to enter the automatic adjustment state.

[0047] In this startup control method, upon receiving a start command for compressor M, the opening of the electronic expansion valve EXV is first adjusted to a first set value and then delayed for a first preset time. This step preliminarily adjusts the refrigerant flow state before compressor M starts, ensuring relatively smooth refrigerant flow during the startup process.

[0048] In addition, after a first preset delay time, the compressor M is controlled to start and enter the minimum load state. This step avoids a sudden pressure change at the moment of starting the compressor M by delaying the start, which helps reduce the risk of liquid refrigerant backflow.

[0049] Furthermore, after the compressor M has run for a second preset time, when it is confirmed that the second pressure on the low-pressure side of the compressor M is greater than the second pressure threshold, the opening of the electronic expansion valve EXV is adjusted to a second set value, so that the pressure on the low-pressure side of the compressor M gradually decreases until it is lower than the second pressure threshold. This ensures that when the compressor M enters a normal working state, the pressure on the low-pressure side of the compressor M is already within a safe range, effectively ensuring that as little liquid refrigerant as possible flows back into the compressor M, thereby avoiding liquid hammer on the compressor M due to liquid return.

[0050] Optionally, the first setting value is greater than the third setting value, and the third setting value is greater than the second setting value.

[0051] As can be seen, the above control method strictly controls the opening and closing state of the electronic expansion valve EXV during the startup and shutdown of compressor M, thereby controlling the pressure on the low-pressure side of compressor M and ensuring that a minimum amount of refrigerant remains on the low-pressure side during shutdown. Furthermore, during startup, this method minimizes the amount of refrigerant returning to compressor M, reducing the risk of liquid hammer and lubricant dilution. This not only protects the mechanical components of compressor M, but also improves lubrication and extends the service life of compressor M. Furthermore, compared to the traditional method of adding a gas-liquid separator, this control method saves physical space in the air conditioning system and does not increase the pressure drop on the suction side of compressor M, thus minimizing the impact on system layout and performance.

[0052] On the other hand, in the stop control method, if the first pressure is greater than the first set value for a duration greater than a third preset duration, the compressor M is controlled to enter a stop state to avoid long waiting times.

[0053] Specifically, if Figure 2 , the above-mentioned stop control method comprises the following steps:

[0054] S10: receiving a stop command of the compressor M;

[0055] S11: Reduce the load of the compressor M to the minimum load;

[0056] S12: Close the opening of the electronic expansion valve EXV to 0%;

[0057] S13: constructing a first timer based on the first preset duration, and starting the first timer;

[0058] S14: Determine whether the first pressure is less than or equal to the first pressure threshold, if yes, proceed to S16, if no, proceed to S15;

[0059] S15: Whether the first timer overflows, if yes, then go to S16, if not, then return to S14:

[0060] S16: Compressor M stops.

[0061] On the other hand, in the startup control method, after the opening of the electronic expansion valve EXV is adjusted to the second set value, if the duration for which the second pressure is greater than the second pressure threshold is greater than the fourth preset time, it means that the current opening of the electronic expansion valve EXV is large, and the net inflow of refrigerant on the low-pressure side of the compressor M is relatively large. Therefore, the opening of the electronic expansion valve EXV is further reduced, for example, by 5% to reach the fourth set value, thereby reducing the amount of refrigerant entering the low-pressure side and accelerating the evacuation of the low-pressure side, so that the second pressure drops rapidly until it is lower than the second set value.

[0062] On the other hand, in the startup control method, if the second pressure is greater than the second pressure threshold for a duration greater than the fifth preset time, and the fifth preset time is greater than the fourth preset time, the opening of the electronic expansion valve EXV is directly adjusted to the third set value, so that the air conditioner enters a normal automatic operation state and avoids being in a waiting state for a long time.

[0063] In this regard, if the first preset time is 15 seconds, the second preset time is 10 seconds, the fourth preset time is 30 seconds, and the fifth preset time is 60 seconds; the first set value is 30% of the total opening of the electronic expansion valve EXV, the second set value is 20% of the total opening of the electronic expansion valve EXV, the third set value is 15% of the total opening of the electronic expansion valve EXV, and the fourth set value is 25% of the total opening of the electronic expansion valve EXV, then the process of the startup control method in the above embodiment is as follows:

[0064] S200: receiving a start instruction of the compressor M;

[0065] S201: Adjust the opening of the electronic expansion valve EXV to 30%;

[0066] S202: After a delay of 15 seconds, start the compressor M so that the compressor M runs at the lowest load;

[0067] S203: After the compressor M runs for 10 seconds, a second timer with a duration of 30 seconds and a third timer with a duration of 60 seconds are established, and the second timer and the third timer are started;

[0068] S204: Determine whether the second pressure on the low-pressure side of the compressor M is less than or equal to the second pressure threshold. If yes, proceed to S211; if not, proceed to S205.

[0069] S205: Adjust the opening of the electronic expansion valve EXV to 20%;

[0070] S206: Determine whether the second timer overflows, if not, proceed to S207, if yes, proceed to S208;

[0071] S207: Determine whether the second pressure on the low-pressure side of the compressor M is less than or equal to the second pressure threshold. If yes, proceed to S211; if not, return to S206;

[0072] S208: Adjust the opening of the electronic expansion valve EXV to 15%;

[0073] S209: Determine whether the second pressure on the low-pressure side of the compressor M is less than or equal to the second pressure threshold. If yes, proceed to S211; if not, proceed to S210.

[0074] S210: Check whether the third timer overflows. If so, proceed to S211; if not, return to S209.

[0075] S210: Adjust the opening of the electronic expansion valve EXV to 25%;

[0076] S211: After another 10s delay, the electronic expansion valve EXV is controlled to enter the automatic adjustment state, and the compressor M automatically runs.

[0077] The present invention also discloses an air-conditioning compressor start-stop control system, which includes one or more processors, a memory, and one or more programs, wherein the one or more programs are stored in the memory and are configured to be executed by the one or more processors, and the programs include instructions for executing the air-conditioning compressor start-stop control method as described above. The processor can be a general-purpose central processing unit (CPU), a microprocessor, an application-specific integrated circuit (ASIC), or one or more integrated circuits for executing relevant programs to implement the functions required to be executed by the modules in the air-conditioning compressor start-stop control system of the embodiment of the present application, or to execute the air-conditioning compressor start-stop control method of the method embodiment of the present application.

[0078] The present invention also discloses a computer-readable storage medium, which includes a computer program, and the computer program can be executed by a processor to implement the air-conditioning compressor start-stop control method as described above. The computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device such as a server or data center that includes one or more available media. The available medium can be a read-only memory (ROM), a random access memory (RAM), or a magnetic medium, such as a floppy disk, a hard disk, a tape, a magnetic disk, or an optical medium, such as a digital versatile disc (DVD), or a semiconductor medium, such as a solid-state disk (SSD).

[0079] The present application also discloses a computer program product or computer program, which includes computer instructions stored in a computer-readable storage medium. A processor of an electronic device reads the computer instructions from the computer-readable storage medium and executes the computer instructions, causing the electronic device to perform the above-described air conditioner compressor start-stop control method.

[0080] The above disclosure is only the preferred embodiment of the present invention, which certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the scope of the patent application of the present invention are still within the scope of the present invention.

Claims

1. A method for controlling the start and stop of an air-conditioning compressor, characterized in that: It includes a start control method for controlling the start of the compressor and a stop control method for controlling the stop of the compressor; The stop control method includes: upon receiving a compressor stop instruction, controlling the compressor to enter a minimum load state and completely closing an electronic expansion valve in a refrigerant main circuit where the compressor is located; When confirming that the first pressure on the low-pressure side of the compressor is less than or equal to a first pressure threshold, controlling the compressor to enter a stopped state; The startup control method comprises: upon receiving a compressor startup instruction, adjusting the opening of the electronic expansion valve to a first set value, delaying for a first preset time, and then controlling the compressor to start and enter a minimum load state; When the compressor runs for a second preset time and it is confirmed that the second pressure on the low-pressure side of the compressor is greater than the second pressure threshold, the opening of the electronic expansion valve is adjusted to a second set value so that the pressure on the low-pressure side of the compressor gradually decreases until the second pressure is less than or equal to the second pressure threshold. The opening of the electronic expansion valve is adjusted to a third set value so that the refrigerant is in a normal circulation state, and the electronic expansion valve is controlled to enter an automatic adjustment state after a preset delay time. In the startup control method, after the opening of the electronic expansion valve is adjusted to the second set value, if the second pressure is greater than the second pressure threshold for a duration greater than a fourth preset time, the opening of the electronic expansion valve is reduced, and the second pressure is continuously compared with the second pressure threshold.

2. The air-conditioning compressor start-stop control method according to claim 1, characterized in that: The first setting value is greater than the third setting value, and the third setting value is greater than the second setting value.

3. The air-conditioning compressor start-stop control method according to claim 1, characterized in that: In the stop control method, if the first pressure is greater than the first pressure threshold for a duration greater than a third preset duration, the compressor is controlled to enter a stop state.

4. The air-conditioning compressor start-stop control method according to claim 1, characterized in that: In the startup control method, if the duration for which the second pressure is greater than the second pressure threshold is greater than a fifth preset duration, the opening of the electronic expansion valve is adjusted to the third set value.

5. An air conditioning system, characterized in that: The air-conditioning system includes a compressor and a condenser and an evaporator connected to the compressor, wherein the compressor is connected to the condenser through a four-way valve, and the condenser is connected to the evaporator through an electronic expansion valve. The air-conditioning system also includes a controller electrically connected to the compressor and the electronic expansion valve, and the controller controls the start and stop of the compressor based on the air-conditioning compressor start and stop control method according to any one of claims 1 to 4.

6. The air conditioning system according to claim 5, characterized in that It also includes an economizer, the three pipeline connection ends of the condenser are respectively connected to the evaporator, the condenser and the compressor, and the electronic expansion valve is arranged on the connecting pipeline between the economizer and the evaporator.

7. An air-conditioning compressor start-stop control system, characterized in that: include: one or more processors; Memory; and one or more programs, wherein the one or more programs are stored in the memory and are configured to be executed by the one or more processors, the programs including instructions for executing the air-conditioning compressor start-stop control method according to any one of claims 1 to 4.

8. A computer-readable storage medium, characterized in that The method comprises a computer program, which can be executed by a processor to implement the air-conditioning compressor start-stop control method according to any one of claims 1 to 4.

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