Air conditioning system

Abstract

This invention proposes an air conditioning system comprising: a chiller unit, a compressor, a condenser, an expansion valve, and an evaporator connected in series via pipelines; the compressor compressing low-temperature, low-pressure refrigerant gas into high-temperature, high-pressure refrigerant gas and discharging it to the condenser; a vibration velocity acquisition module monitoring the casing vibration velocity; a pressure sensor monitoring the compressor discharge pressure; and a controller electrically connected to the compressor, the vibration velocity acquisition module, the pressure sensor, and the speed sensor; the controller is configured to: determine the compressor vibration velocity and discharge pressure fluctuation values ​​based on the casing vibration velocity and discharge pressure according to a first logic, and perform logical judgment based on preset conditions; when the compressor meets surge prevention or surge avoidance conditions, actively intervene to avoid frequent protective shutdowns and extend the compressor's service life.

Description

Technical Field

[0001] This invention belongs to the field of air conditioning technology, and in particular relates to an air conditioning system. Background Technology

[0002] An air conditioning system generally refers to equipment that uses artificial means to regulate and control parameters such as temperature, humidity, and airflow rate of the ambient air in a regulated room. An air conditioning system typically includes multiple chiller units. In these units, refrigerant circulates sequentially through the compressor, condenser, throttling device, and evaporator to achieve cooling and heating. Oil-free centrifugal refrigeration compressors utilize magnetic levitation bearings and permanent magnet synchronous motor technology. They compress gas through centrifugal force generated by the high-speed rotation of the impeller, completely eliminating the frictional losses of traditional mechanical bearings. This allows the compressor speed to exceed 100,000 rpm. With its advantages of high efficiency, energy saving, stable operation, easy maintenance, and environmental friendliness, it is widely used in air conditioning systems.

[0003] However, because these compressors use dynamic pressure air bearings, they cannot have built-in bearing position sensors, thus lacking real-time monitoring of the bearing's suspension state. This makes it impossible for the compressor to monitor the bearing's suspension state in real time, increasing the risk of compressor failure during operation. Furthermore, the compressor in an air conditioning system is typically tightly integrated with multiple components such as the condenser, evaporator, and expansion valve, and the operating status of the air conditioning system is greatly affected by external environmental factors (such as outdoor temperature and load changes). This makes it difficult to provide timely and effective early warning and control when surge or abnormal vibration occurs.

[0004] Currently, protective measures against compressor surge and abnormal vibration mainly rely on surge curves fitted by the compressor manufacturer and the overall control system of the chiller unit. Surge curves are fitted by the manufacturer using actual operating data during compressor operation. While this can effectively prevent surge under most operating conditions, deviations may still occur under certain conditions, especially near the system's limits, leading to surge avoidance failure.

[0005] Furthermore, in existing air conditioning systems, the chiller controller monitors the compressor's operating status, and the common control logic is still passive protection. That is, the system only initiates protective actions, such as compressor unloading, when current fluctuations reach a set threshold. This protection strategy has several obvious drawbacks:

[0006] Irreversible compressor damage: When compressor current fluctuations are significant and persist at a certain frequency, it indicates that the compressor has experienced severe surge or abnormal vibration. At this point, the control system's protective mechanisms typically only activate when the bearings have already shown significant wear, which is irreversible, preventing the compressor from returning to normal operation.

[0007] Frequent surge leads to shortened lifespan: In some demanding air conditioning applications, especially when the air conditioning system load fluctuates significantly, the compressor's operating conditions often approach or exceed the design range, resulting in a higher frequency of surge and abnormal vibration. Frequent surge accelerates the mechanical wear of the compressor, significantly shortening its lifespan.

[0008] Delayed start-up of protective measures can cause instability: After surge occurs, the delayed start-up of protective measures may cause the compressor to alarm and shut down. This not only affects the operational stability of the air conditioning system, but may also cause fluctuations in indoor temperature. Frequent start-ups and shutdowns will further affect the overall performance and stability of the air conditioning unit, causing inconvenience to users.

[0009] The impact of temperature difference between inside and outside the air conditioning system and operating load: The condenser and evaporator of the air conditioning system are closely related to changes in ambient temperature during system operation. Especially under high temperature load or extreme operating conditions, traditional protection methods often cannot respond to system changes in a timely manner. Therefore, more accurate and sensitive monitoring and prevention measures are needed to avoid frequent failures of the air conditioning system in harsh environments.

[0010] Therefore, existing technical solutions have failed to effectively address the surge and abnormal vibration monitoring issues faced by compressors in air conditioning systems, and cannot achieve real-time, proactive protection. This not only affects the overall operational stability of the air conditioning system but also exacerbates compressor wear and reduces its service life. Summary of the Invention

[0011] This invention aims to at least partially solve one of the technical problems in the related art. Therefore,

[0012] According to embodiments of this disclosure, an air conditioning system is provided, comprising:

[0013] A chiller unit consists of a compressor, condenser, expansion valve, and evaporator connected in series via pipelines. The compressor is used to compress low-temperature, low-pressure refrigerant gas into high-temperature, high-pressure refrigerant gas and discharge it to the condenser.

[0014] A vibration velocity acquisition module is fixed to the casing of the compressor and is used to monitor the vibration velocity of the casing.

[0015] A pressure sensor is installed at the exhaust port of the compressor to monitor the exhaust pressure of the compressor.

[0016] The controller is electrically connected to the compressor, the vibration velocity acquisition module, and the pressure sensor.

[0017] The controller is configured to:

[0018] The compressor's operating speed, casing vibration velocity, and discharge pressure are obtained. Based on the casing vibration velocity and discharge pressure, the compressor's vibration velocity and discharge pressure fluctuation values ​​are determined according to a first logic. It is then determined whether the vibration velocity, discharge pressure fluctuation values, and operating speed meet any of the following conditions: normal operation conditions, surge prevention conditions, surge avoidance conditions, and protective shutdown conditions.

[0019] If surge prevention conditions, surge avoidance conditions, or protection shutdown conditions are met, the compressor is controlled to perform corresponding adjustment actions to predict and actively intervene in surge risks, effectively ensuring system stability and operating efficiency.

[0020] If normal operating conditions are met, then control the compressor to operate normally;

[0021] The normal operating conditions, surge prevention conditions, surge avoidance conditions, or protection shutdown conditions are configured with corresponding critical conditions based on the vibration velocity, exhaust pressure fluctuation value, and operating speed.

[0022] Compared to traditional control methods that rely on a single parameter (such as pressure or current), the embodiments of this application use a combination of three parameters—vibration velocity, exhaust pressure fluctuation value, and operating speed—to more accurately identify potential surge conditions, thereby enabling effective avoidance measures to be taken before problems occur.

[0023] In some embodiments, the controller is configured to:

[0024] Determine whether the vibration speed, exhaust pressure fluctuation value, and operating speed meet the normal operating conditions. If so, determine that the compressor is operating normally.

[0025] The normal operating conditions are configured as follows:

[0026] The vibration velocity is lower than the normal vibration velocity threshold, the exhaust pressure fluctuation value is lower than the normal pressure threshold, and the difference between the operating speed and the surge speed is higher than the normal speed difference.

[0027] Based on the above configuration, this embodiment sets three critical thresholds: normal vibration velocity threshold, normal pressure threshold, and normal speed difference, avoiding the possibility of misjudgment based on a single indicator. This effectively enhances the ability to identify surge critical points, enabling the controller to accurately determine whether it is in a stable operating state at an early stage, thereby achieving more intelligent and efficient operation scheduling.

[0028] In some embodiments, the controller is configured to:

[0029] Determine whether the vibration velocity, exhaust pressure fluctuation value and operating speed meet the surge prevention conditions. If so, determine that the compressor is in surge prevention state and control the compressor to perform a frequency limiting action.

[0030] The surge prevention condition is met if any of the following conditions are met:

[0031] The vibration velocity reaches or exceeds the normal vibration velocity threshold but is below the surge vibration velocity threshold.

[0032] The exhaust pressure fluctuation value reaches above the normal pressure threshold but is below the surge pressure threshold;

[0033] The difference between the operating speed and the surge speed is below the normal speed difference but higher than the surge speed difference.

[0034] Based on the above configuration, this embodiment determines whether the compressor has entered the early stage of surge risk based on multi-dimensional parameters and adopts a preventive control strategy. Based on the above surge prevention conditions, namely the degree of mechanical vibration, airflow stability, and speed safety margin, upper and lower limit ranges are set respectively to form an "early warning zone".

[0035] Once any parameter falls into the warning zone, that is, between the normal state and the surge threshold, the controller determines that the compressor has entered the surge prevention state.

[0036] To prevent the compressor from continuing to increase its frequency and causing surge, the controller immediately controls the compressor to perform a frequency limiting operation, that is, to limit the frequency increase of the compressor motor by the frequency converter, maintain the current operating speed or reduce it appropriately, and ensure system stability.

[0037] In some embodiments, the controller is configured to:

[0038] Determine whether any of the vibration velocity, exhaust pressure fluctuation value, and operating speed meets the surge avoidance condition. If so, determine that the compressor is in a surge avoidance state and control the compressor to perform a forced frequency reduction action.

[0039] The surge avoidance condition is met if any of the following conditions are met:

[0040] The vibration velocity reaches or exceeds the surge velocity threshold but is lower than the shutdown velocity threshold.

[0041] The exhaust pressure fluctuation value reaches or exceeds the surge pressure threshold but is lower than the shutdown pressure threshold;

[0042] The difference between the operating speed and the surge speed is below the surge speed difference but higher than the shutdown speed difference.

[0043] Based on the above configuration, the controller in this embodiment has a built-in surge avoidance judgment logic, which includes a set of intermediate thresholds that are stricter than surge prevention conditions but more lenient than shutdown conditions. When any monitored parameter exceeds the surge warning line but has not yet reached the shutdown standard, it is considered that there is a significant surge risk, and the controller determines the compressor status to a surge avoidance state.

[0044] At this time, the controller performs a forced frequency reduction action, that is, controls the frequency converter to significantly reduce the frequency of the compressor motor, thereby reducing the compressor speed, rapidly widening the gap between the operating speed and the surge critical speed, and reducing the gas disturbance and vibration intensity in the system, effectively avoiding the occurrence of surge instability.

[0045] In some embodiments, the controller is configured to:

[0046] Determine whether any of the vibration speed, exhaust pressure fluctuation value, and operating speed reaches the protection shutdown condition. If so, determine that the compressor is in the protection shutdown state and control the compressor to perform a shutdown action.

[0047] The protection shutdown condition is met if any of the following conditions are met:

[0048] The vibration velocity reaches or exceeds the shutdown vibration velocity threshold.

[0049] The exhaust pressure fluctuation value reaches or exceeds the shutdown pressure threshold;

[0050] The difference between the operating speed and the surge speed is below the difference between the stopping speed and the operating speed.

[0051] Based on the above configuration, once the controller detects that any parameter exceeds the corresponding limit value (stop vibration speed threshold, stop pressure threshold, stop differential speed value), it indicates that the compressor is vibrating violently, the pressure is fluctuating violently, or the speed is too low and close to the surge point. The controller will immediately determine the compressor status to the protection stop state.

[0052] By setting an irreversible protection shutdown mechanism, the controller can respond quickly when faced with serious anomalies, avoiding compressor burnout or mechanical damage caused by continuous operation, and significantly improving the safety level and stability of the air conditioning system equipment.

[0053] In some embodiments, the vibration velocity acquisition module includes:

[0054] The first vibration velocity sensor and the second vibration velocity sensor are mounted on the housing along the axial direction of the compressor and are used to acquire the first vibration velocity signal and the second vibration velocity signal.

[0055] The third and fourth vibration velocity sensors are arranged radially on the compressor housing to acquire the third and fourth vibration velocity signals.

[0056] In some embodiments, the first logic is configured as follows:

[0057] The vibration velocity of the compressor is calculated based on the first, second, third, and fourth vibration velocity signals. Specifically, the vibration velocity... The calculation was obtained based on the following computational model:

[0058] .

[0059] In some embodiments, the first logic is further configured to:

[0060] The exhaust pressure fluctuation value is calculated based on the highest and lowest exhaust pressure values ​​within a preset period.

[0061] According to embodiments of this disclosure, an air conditioning system is also provided, comprising:

[0062] A chiller unit consists of a compressor, condenser, expansion valve, and evaporator connected in series via pipelines. The compressor is used to compress low-temperature, low-pressure refrigerant gas into high-temperature, high-pressure refrigerant gas and discharge it to the condenser.

[0063] A vibration velocity acquisition module is fixed to the casing of the compressor and is used to monitor the vibration velocity of the casing.

[0064] A pressure sensor is installed at the exhaust port of the compressor to monitor the exhaust pressure of the compressor.

[0065] The controller is electrically connected to the compressor, the vibration velocity acquisition module, and the pressure sensor.

[0066] The controller is configured to:

[0067] The compressor's operating speed, the casing vibration velocity, and the discharge pressure are obtained. Based on the casing vibration velocity, discharge pressure, and operating current, the compressor's vibration velocity, discharge pressure fluctuation value, and operating speed are determined according to the first logic.

[0068] Determine whether the vibration velocity, exhaust pressure fluctuation value, and operating speed meet the surge prevention conditions; if so, control the compressor to perform frequency limiting.

[0069] After the compressor performs the frequency limiting action, if it is determined that the vibration speed, exhaust pressure fluctuation value and operating speed meet the normal operating conditions and last for at least a first preset time, then the compressor is controlled to cancel the frequency limiting action.

[0070] Based on the above configuration, parameter stability is ensured by a preset first duration condition, avoiding frequent switching caused by instantaneous fluctuations, improving the robustness of the control logic, and making it particularly suitable for complex working environments with frequent load changes. This further ensures the efficient and stable operation of the compressor and extends its service life.

[0071] In some embodiments, the controller is further configured to:

[0072] Determine whether the vibration velocity, exhaust pressure fluctuation value, and operating speed meet the surge avoidance conditions. If so, control the compressor to perform a forced frequency reduction action.

[0073] After the compressor is controlled to perform a forced frequency reduction action, if it is determined that the vibration speed, exhaust pressure fluctuation value and operating speed meet the surge avoidance exit conditions, then the compressor is controlled to cancel the forced frequency reduction action.

[0074] The surge avoidance exit condition is as follows:

[0075] The vibration velocity is below the surge velocity threshold and lasts for at least the second preset duration.

[0076] The exhaust pressure fluctuation value is lower than the surge pressure threshold and lasts for at least the second preset duration, and

[0077] The difference between the operating speed and the surge speed is higher than the surge speed difference and lasts for at least the second preset duration.

[0078] Based on the above configuration, this application also performs closed-loop control on surge avoidance, which significantly improves system operating efficiency, energy-saving performance and long-term safety and stability, and greatly enhances the reliability of the system's surge risk assessment.

[0079] By setting a second preset duration, the compressor status is ensured to truly return to stability, eliminating misjudgments caused by short-term interference or data fluctuations, ensuring the continuous stability of parameters, and improving the control accuracy and system robustness during the compressor's operating state transition process. Attached Figure Description

[0080] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0081] Figure 1 This is a structural block diagram of an air conditioning system according to an embodiment of this application;

[0082] Figure 2 This is a schematic diagram of the structure of a chiller unit according to an embodiment of this application;

[0083] Figure 3 This is another structural schematic diagram of a chiller unit according to an embodiment of this application;

[0084] Figure 4 This is another structural block diagram of an air conditioning system according to an embodiment of this application;

[0085] Figure 5This is a schematic diagram of the process for determining whether the compressor is in normal operating condition according to an embodiment of this application;

[0086] Figure 6 This is a schematic diagram of the process for determining whether a compressor is in a surge prevention state according to an embodiment of this application;

[0087] Figure 7 This is a schematic diagram of the process for determining whether a compressor is in a surge avoidance state according to an embodiment of this application;

[0088] Figure 8 This is a schematic diagram of the process for determining whether the compressor is in a protective shutdown state according to an embodiment of this application;

[0089] Figure 9 This is a schematic diagram of the judgment process for another compressor being in surge prevention state according to an embodiment of this application;

[0090] Figure 10 This is a schematic diagram of the judgment process for another compressor being in a surge avoidance state according to an embodiment of this application;

[0091] Figure 11 This is a schematic diagram of another state determination process for the compressor according to an embodiment of this application.

[0092] In the above figures:

[0093] Air conditioning system 100; controller 2; vibration velocity acquisition module 21; pressure sensor 22;

[0094] Speed ​​sensor 23; Current transmitter 24; Chiller unit 1; Compressor 11; Condenser 12;

[0095] Expansion valve 13; Evaporator 14; IGV actuator 15; Suction pressure sensor 16; Detailed Implementation

[0096] To make the objectives, technical solutions, and advantages of this application clearer, the application is described and illustrated below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application. All other embodiments obtained by those skilled in the art based on the embodiments provided in this application without inventive effort are within the scope of protection of this application.

[0097] Obviously, the accompanying drawings described below are merely some examples or embodiments of this application. Those skilled in the art can apply this application to other similar scenarios based on these drawings without any inventive effort. Furthermore, it is understood that although the efforts made in this development process may be complex and lengthy, for those skilled in the art related to the content disclosed in this application, any changes to design, manufacturing, or production based on the technical content disclosed in this application are merely conventional technical means and should not be construed as insufficient disclosure of the content of this application.

[0098] In this application, the reference to "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that is mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this application may be combined with other embodiments without conflict.

[0099] The terms "connection," "linked," and "coupled" used in this application are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. "Multiple" in this application refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, "A and / or B" can represent: A alone, A and B simultaneously, and B alone. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. The terms "first," "second," and "third" used in this application are merely to distinguish similar objects and do not represent a specific ordering of objects.

[0100] like Figure 1 As shown, the air conditioning system 100 in this application includes a chiller unit 1, which performs the refrigeration cycle of the air conditioning system through a compressor 11, a condenser 12, an expansion valve 13, and an evaporator 14. The refrigeration cycle includes a series of processes involving compression, condensation, expansion, and evaporation, and supplies refrigerant to the conditioned and heat-exchanged air.

[0101] Compressor 11 compresses the refrigerant gas under high temperature and high pressure and discharges the compressed refrigerant gas. The discharged refrigerant gas flows into condenser 12. Condenser 12 condenses the compressed refrigerant into a liquid phase, and heat is released to the surrounding environment through the condensation process.

[0102] Expansion valve 13 expands the high-temperature, high-pressure liquid refrigerant condensed in condenser 12 into a low-pressure liquid refrigerant. Evaporator 14 evaporates the refrigerant that has expanded in the expansion valve and returns the low-temperature, low-pressure refrigerant gas to the compressor. Evaporator 14 achieves a cooling effect by utilizing the latent heat of refrigerant evaporation to exchange heat with the material to be cooled.

[0103] In related technologies, the vibration of the compressor 11 during operation will cause vibration of the exhaust pipe and intake pipe connected to it. During surge, the intake pipe will experience significant backflow, causing instantaneous fluctuations in exhaust pressure. When the vibration speed of the compressor 11 casing exceeds the surge velocity threshold of this application, the corresponding exhaust pressure will also fluctuate significantly. Similarly, the difference between the surge velocity and the operating speed of the compressor 11 will also be affected.

[0104] This invention provides an air conditioning system, as described below. Figures 2-11 The air conditioning system provided in this application is described.

[0105] refer to Figure 2 As shown, the exhaust port of compressor 11 is connected to the inlet of condenser 12, and the expansion valve 13 is connected to the outlet of condenser 12. The high-temperature and high-pressure refrigerant gas flowing out of the exhaust port of compressor 11 flows into condenser 12 through the exhaust pipe.

[0106] Optionally, the compressor 11 includes a sealed housing and a drive module and an air module located within the housing. The drive module includes a motor, a rotor, and oil-free bearings. The air module has a centrifugal impeller driven by the drive module to compress the working fluid.

[0107] The air conditioning system 100 may include a controller 2. The controller 2 is connected to the existing controller of the chiller unit 1 or the existing controller of the air conditioning system 100, or it may be a built-in unit module of the existing controller of the air conditioning system 100. The controller 2 is configured to control the operation of each component in the air conditioning system 100 so that the operation of each component of the air conditioning system 100 can realize the predetermined function of the air conditioning system 100.

[0108] For example, controller 2 is a central processing unit (CPU), a general-purpose processor, a network processor (NP), a digital signal processor (DSP), a microcontroller unit (MCU), or any combination thereof.

[0109] The air conditioning system 100 may include a vibration velocity acquisition module 21. The vibration velocity acquisition module 21 is fixed to the housing of the compressor 11 and is used to monitor the vibration velocity of the housing.

[0110] The air conditioning system 100 may include a pressure sensor 22. The pressure sensor 22 is located at the exhaust port of the compressor 11 and is used to monitor the exhaust pressure of the compressor 11.

[0111] In another embodiment, combined Figure 4 As shown, the air conditioning system 100 may include a speed sensor 23, such as a photoelectric encoder or a magnetoelectric sensor. The speed sensor 23 is located at the coupling of the compressor 11 and is used to directly measure the rotational speed of the motor or compressor rotor, and monitor the operating speed of the motor in the compressor 11.

[0112] The controller 2 is electrically connected to at least the compressor 11, the vibration velocity acquisition module 21, the pressure sensor 22, and the speed sensor 23, or the speed sensor 23 is not required and the controller 2 is directly electrically connected to the compressor's drive controller to read the operating speed in real time.

[0113] refer to Figure 2 As shown, the chiller unit 1 may include an IGV (Inlet Guide Vane) actuator 15, used to receive instructions from the controller 2 and adjust the opening of the inlet guide vane. By limiting the gas flow rate into the compressor, the cooling capacity (load) is reduced; by increasing the gas flow rate into the compressor, the cooling capacity (load) is increased.

[0114] refer to Figure 3 As shown, the chiller unit 1 may include a suction pressure sensor 16. The suction pressure sensor 16 is located at the inlet of the compressor 11 and electrically connected to the controller 2, and is used to monitor the refrigerant pressure at the inlet of the compressor 11 in real time and transmit the pressure signal to the controller 2.

[0115] Controller 2 can be configured to determine the vibration velocity of compressor 11 based on the aforementioned housing vibration velocity and exhaust pressure according to the first logic. Exhaust pressure fluctuation value Thus, the vibration velocity is obtained. Exhaust pressure fluctuation value and operating speed.

[0116] Then, determine the aforementioned vibration velocity. Exhaust pressure fluctuation value And whether the operating speed meets any of the following conditions: normal operating conditions, surge prevention conditions, surge avoidance conditions, and protection shutdown conditions.

[0117] Specifically, if surge prevention conditions, surge avoidance conditions, or protection shutdown conditions are met, the compressor 11 is controlled to perform corresponding adjustment actions to predict and actively intervene in surge risks, effectively ensuring system stability and operating efficiency.

[0118] Specifically, if the normal operating conditions are met, the compressor 11 will be controlled to operate normally;

[0119] The aforementioned normal operating conditions, surge prevention conditions, surge avoidance conditions, or protective shutdown conditions are based on vibration velocity and exhaust pressure fluctuation values. The operating speed is configured with corresponding critical conditions.

[0120] In some embodiments, the vibration velocity acquisition module 21 may include: a first vibration velocity sensor, a second vibration velocity sensor, a third vibration velocity sensor, and a fourth vibration velocity sensor that are electrically connected to the controller 2.

[0121] The first vibration velocity sensor and the second vibration velocity sensor are symmetrically arranged on the housing along the axial direction of the compressor 11 to acquire the first vibration velocity signal. Second vibration velocity signal .

[0122] The third and fourth vibration velocity sensors are symmetrically arranged on the housing along the radial direction of the compressor 11 to acquire the third vibration velocity signal. Fourth vibration velocity signal .

[0123] It should be understood that axial direction generally refers to the direction along the centerline of the main shaft, that is, the direction of rotation of the compressor rotor 11. Radial direction refers to the direction radiating outward from the shaft center, forming a 90° angle with the axis. The main direction of gas flow in the impeller of the centrifugal compressor in this embodiment is radial.

[0124] In some embodiments, the first logic can be configured to: based on a first vibration velocity signal Second vibration velocity signal Third vibration velocity signal and the fourth vibration velocity signal Calculate the vibration velocity of compressor 11 .

[0125] Specifically, vibration velocity The calculation was obtained based on the following computational model:

[0126] .

[0127] In some embodiments, the first logic may also be configured to: calculate the exhaust pressure fluctuation value based on the highest and lowest exhaust pressure values ​​within a preset period. Optionally, in this embodiment, the ten seconds preceding the current moment are selected as the preset period. The exhaust pressure fluctuation value is calculated by subtracting the highest and lowest values ​​obtained from the exhaust pressure changes over the previous ten seconds. .

[0128] For example, but not limited to, the controller in this application uses a PLC controller.

[0129] Regarding the controller, although a PLC controller is used, it can be replaced with an embedded microcontroller controller, a DSP processor, or an industrial control host based on edge computing, depending on the system requirements.

[0130] This application embodiment sets up multiple sensing modules and connects them to the controller to realize real-time monitoring and dynamic control of the compressor 11's operating status, and combines the casing vibration speed, exhaust pressure, and operating speed to control surge.

[0131] Compared to traditional control methods that rely on a single parameter (such as pressure or current), the combined judgment of three parameters—vibration velocity, exhaust pressure fluctuation value, and operating speed—can more accurately identify potential surge conditions, thereby taking effective avoidance measures before problems occur, improving the stability and reliability of system operation, significantly reducing the risk of compressor damage, and improving energy efficiency through optimized control algorithms.

[0132] refer to Figure 5 As shown, controller 2 can be configured to: acquire vibration velocity. Exhaust pressure fluctuation value And the operating speed (step S100), determine the vibration velocity. Exhaust pressure fluctuation value If the compressor 11 is in normal operating condition, and the compressor speed is at normal operating condition (step S110), then the compressor 11 is determined to be in normal operating condition and continues to maintain normal operating condition (step S120).

[0133] Specifically, the normal operating conditions can be configured as follows: vibration velocity Below the normal vibration velocity threshold, exhaust pressure fluctuation value Below the normal pressure threshold and the difference between the operating speed and the surge speed. Higher than normal speed difference.

[0134] It should be noted that the controller 2 is pre-configured with a compressor surge curve. Based on the compressor surge curve, the compressor speed data is matched to determine whether the operating speed of the compressor 11 is close to the surge speed when it is running at a certain compression ratio.

[0135] Based on the above configuration, this embodiment sets three critical thresholds: normal vibration velocity threshold, normal pressure threshold, and normal rotational speed difference, avoiding the possibility of misjudgment based on a single indicator. Vibration velocity The discharge pressure fluctuation value reflects the severity of the mechanical vibration of compressor 11. The difference between the operating speed and the surge speed represents the stability of the gas flow. This is used to measure whether the system is close to the surge critical point.

[0136] When the monitored value meets all three judgment conditions, namely, the vibration speed is low, the pressure fluctuation is stable, and the speed is sufficiently higher than the surge critical speed, the controller determines that the compressor 11 is operating in a safe and normal state.

[0137] In particular, by using the difference between the surge speed and the surge speed as one of the judgment conditions, the ability to identify the surge critical point is effectively enhanced, enabling the controller to accurately determine whether it is in a stable operating state in the early stage, thereby achieving more intelligent and efficient operation scheduling.

[0138] In some embodiments, reference Figure 6 As shown, controller 2 can be configured to: acquire vibration velocity. Exhaust pressure fluctuation value And the operating speed (step S100), determine the vibration velocity. Exhaust pressure fluctuation value If the operating speed reaches the surge prevention condition (step S210), then the compressor 11 is determined to be in surge prevention state, and the compressor 11 is controlled to perform the frequency limiting action (step S220).

[0139] Surge prevention conditions are met if any of the following conditions are met: vibration velocity Reaching a normal vibration velocity threshold but below the surge vibration velocity threshold; exhaust pressure fluctuation value The pressure reaches above the normal pressure threshold but below the surge pressure threshold; the difference between the operating speed and the surge speed. It reaches below the normal speed difference but above the surge speed difference.

[0140] Based on the above configuration, this embodiment determines whether the compressor 11 has entered the early stage of surge risk based on multi-dimensional parameters and adopts a preventive control strategy. Based on the above surge prevention conditions, namely the degree of mechanical vibration, airflow stability, and speed safety margin, upper and lower limit ranges are set respectively to form an "early warning zone".

[0141] Once any parameter falls into the warning zone, that is, between the normal state and the surge threshold, the controller determines that the compressor 11 has entered the surge prevention state.

[0142] To prevent compressor 11 from continuing to increase its frequency and causing surge, the controller immediately controls compressor 11 to perform a frequency limiting operation, that is, to limit the frequency increase of compressor 11 motor by the frequency converter, maintain the current operating speed or reduce it appropriately, and ensure system stability.

[0143] Compared to traditional methods that address surge only after it occurs, this embodiment has stronger proactive prevention capabilities, significantly reducing the incidence of surge events, thereby effectively reducing system operational fluctuations and mechanical wear, and extending equipment lifespan.

[0144] Furthermore, by limiting frequency increase rather than directly reducing frequency, this embodiment can achieve risk control while ensuring that the cooling (or heating) capacity remains basically unchanged, thereby improving the flexibility of the control strategy and energy utilization efficiency.

[0145] In the above embodiments, the specific methods for limiting the frequency increase action may include: maintaining a fixed speed, limiting the maximum frequency, or predictive control based on historical trends, and may also be linked with external load regulation strategies.

[0146] In the above embodiments, the threshold values ​​in the surge prevention conditions can be flexibly set according to the equipment characteristics, operating environment and design conditions. For example, the surge pressure threshold can be appropriately increased when operating under high load in summer.

[0147] In some embodiments, reference Figure 7 As shown, controller 2 can be configured as follows:

[0148] Obtain vibration velocity Exhaust pressure fluctuation value And the operating speed (step S100), determine the vibration velocity. Exhaust pressure fluctuation value If either the operating speed or the speed reaches the surge avoidance condition (step S310), then the compressor 11 is determined to be in the surge avoidance state, and the compressor 11 is controlled to perform a forced frequency reduction action (step S320).

[0149] Specifically, surge avoidance conditions are met if any of the following conditions are met: vibration velocity The surge velocity reaches or exceeds the surge velocity threshold but is below the shutdown velocity threshold; exhaust pressure fluctuation value The surge pressure threshold is reached but below the shutdown pressure threshold; the difference between the operating speed and the surge speed. The speed difference reaches below the surge speed difference but above the shutdown speed difference.

[0150] Based on the above configuration, the controller in this embodiment has a surge avoidance judgment logic, which includes a set of intermediate thresholds that are stricter than surge prevention conditions but looser than shutdown conditions. When any monitored parameter exceeds the surge warning line but has not yet reached the shutdown standard, it is considered that there is a significant surge risk, and the controller determines the state of compressor 11 as a surge avoidance state.

[0151] At this time, the controller performs a forced frequency reduction action, that is, controls the frequency converter to significantly reduce the frequency of the compressor 11 motor, thereby reducing the compressor speed, rapidly widening the gap between the operating speed and the surge critical speed, and reducing the gas disturbance and vibration intensity in the system, effectively avoiding the occurrence of surge instability.

[0152] Therefore, compared with limiting the frequency increase in surge prevention mode, adopting a more aggressive frequency reduction control method in surge avoidance mode can quickly intervene when the air conditioning system is about to enter an unstable state, effectively preventing the compressor from entering an irreversible surge process and ensuring the safe operation of equipment and system.

[0153] In addition, the surge avoidance condition adopts a strategy that triggers when any parameter exceeds its limit, without relying on complex joint judgments, resulting in a faster response. It is particularly suitable for rapid protection needs under sudden load fluctuations or extreme operating conditions, improving the overall robustness and emergency handling capability of the control strategy.

[0154] Considering that during the transition from stable operating conditions to surge conditions, the suction pressure and discharge pressure of compressor 11 will experience pulsating peaks, the changes in the operating conditions of the suction and discharge ports of compressor 11 directly lead to the oscillation of its operating current.

[0155] Based on the above considerations, the surge avoidance conditions in this application embodiment can also be determined based on the operating current to enhance the ability to identify surge signs caused by electrical disturbances.

[0156] The air conditioning system 100 may include a current transmitter 24. The current transmitter 24 is electrically connected to the motor circuit of the compressor 11 and is used to monitor the operating current of the compressor 11. The controller 2 is electrically connected to the current transmitter 24.

[0157] Specifically, surge avoidance conditions also include: the amplitude of the operating current. Whether the preset ratio of the operating value has been reached and the pulse frequency of the operating current in the previous ten seconds. Whether it has been done more than three times.

[0158] The preset ratio is 3%. This value can be adjusted according to the actual operating current of the compressor 11.

[0159] In another embodiment, when the controller determines that the compressor 11 is in a surge avoidance state and controls the compressor 11 to perform a forced frequency reduction action, it also considers the vibration velocity. Exhaust pressure fluctuation value and amplitude Either one of them is used for PID control of the hot gas bypass valve.

[0160] Based on this, the controller first reduces the load on compressor 11 by forcibly reducing the frequency, quickly alleviating fluid disturbances. Secondly, it uses the abnormal parameters causing the surge tendency as input variables for PID control to adjust the opening of the hot gas bypass valve in real time. This embodiment, by actively adjusting the gas path, enables the air conditioning system to have stronger stability and recovery capabilities, reduces the wear rate of compressor 11, and improves operational stability and energy efficiency.

[0161] In PID control, the proportional (P) part responds to the instantaneous magnitude of the parameter deviation, the integral (I) part accumulates the historical deviation trend, and the derivative (D) part predicts the future disturbance development trend. This hot gas bypass regulation can be used to adjust exhaust pressure or maintain stable flow, avoiding surge phenomena induced by rapid changes in operating conditions.

[0162] In some embodiments, reference Figure 8 As shown, controller 2 is configured as follows:

[0163] Obtain vibration velocity Exhaust pressure fluctuation value And the operating speed (step S100), determine the vibration velocity. Exhaust pressure fluctuation value If either the operating speed or the speed reaches the protection shutdown condition (S410), then the compressor 11 is determined to be in the protection shutdown state, and the compressor 11 is controlled to immediately or within 3 seconds to perform a shutdown action (S420).

[0164] Specifically, the protection shutdown condition is met if any of the following conditions are met: vibration velocity The vibration velocity reaches or exceeds the shutdown threshold; exhaust pressure fluctuation value The shutdown pressure threshold is reached or exceeded; the difference between the operating speed and the surge speed is... The speed difference at which the machine stops is below the threshold.

[0165] Based on the above configuration, once the controller detects that any parameter exceeds the corresponding limit value (stop vibration speed threshold, stop pressure threshold, stop differential speed value), it indicates that the compressor 11 is vibrating violently, the pressure is fluctuating violently, or the speed is too low and close to the surge point. The controller will immediately determine the state of the compressor 11 as a protection stop state.

[0166] By setting an irreversible protection shutdown mechanism, the controller can respond quickly when faced with serious anomalies, avoiding the burnout of compressor 11 or damage to the mechanical structure caused by continuous operation, and significantly improving the safety level and stability of the air conditioning system equipment.

[0167] In this embodiment, the normal vibration velocity threshold, surge vibration velocity threshold, and shutdown vibration velocity threshold are configured to increase sequentially. For example, but not limited to, the normal vibration velocity threshold is configured to be 0.4 mm / s, the surge vibration velocity threshold is configured to be 0.6 mm / s, and the shutdown vibration velocity threshold is configured to be 0.8 mm / s.

[0168] In this embodiment, the normal pressure threshold, surge pressure threshold, and shutdown pressure threshold are configured to increase sequentially. For example, but not limited to, the normal pressure threshold is configured as 6 kPa / s, the surge pressure threshold is configured as 10 kPa / s, and the shutdown pressure threshold is configured as 12 kPa / s.

[0169] In this embodiment, the normal speed difference, surge speed difference, and shutdown speed difference are configured to decrease sequentially. For example, but not limited to, the normal speed difference is configured as 200 rpm, the surge speed difference as 120 rpm, and the shutdown speed difference as 50 rpm. Based on the above configuration, refer to... Figure 11 As shown:

[0170] If the vibration speed of compressor 11 is detected Below 0.4 mm / s, exhaust pressure fluctuation value Below 6 kPa / s and the difference between operating speed and surge speed If the speed is above 200 rpm, the compressor 11 is determined to be in normal operation, and the compressor 11 is controlled to continue to operate normally.

[0171] If the vibration speed of compressor 11 is detected The pressure fluctuation reaches 0.4 mm / s or higher but is lower than 0.6 mm / s; or the exhaust pressure fluctuation value... Reaching a speed of 6 kPa / s or higher but below 10 kPa / s; or the difference between the operating speed and the surge speed. If the speed reaches below 200 rpm but above 120 rpm, it is determined that compressor 11 has entered surge prevention mode.

[0172] At this time, the controller sends a control command to the compressor 11 to control the compressor 11 to perform the frequency limiting action and continuously monitor the compressor 11. When the following surge prevention exit conditions are met, the controller determines that the compressor 11 exits the surge prevention state and switches back to the normal operation state.

[0173] In the above embodiments, the surge prevention exit condition includes: the vibration velocity of the compressor 11. Below 0.4 mm / s and maintained for at least 10 seconds; exhaust pressure fluctuation value The pressure is below 6 kPa / s and maintained for at least 10 seconds; and the difference between the operating speed and the surge speed. Run at 200 rpm or higher for at least 10 seconds.

[0174] If the vibration speed of compressor 11 is detected The exhaust pressure fluctuation value is above 0.6 mm / s but below 0.8 mm / s; or the exhaust pressure fluctuation value is... Reaching a value above 10 kPa / s but below 12 kPa / s; or the difference between the operating speed and the surge speed. If the speed reaches below 120 rpm but above 50 rpm, it is determined that compressor 11 has entered a surge avoidance state.

[0175] At this time, the controller sends a control command to the compressor 11 to control the compressor 11 to perform a forced frequency reduction action, and continuously monitors the compressor 11. When it is detected that the surge avoidance exit condition is met, it determines that the compressor 11 exits the surge avoidance state and returns to the surge prevention state.

[0176] In the above embodiments, the surge prevention exit condition includes: the vibration velocity of the compressor 11. Below 0.6 mm / s and maintained for at least 15 seconds; exhaust pressure fluctuation value The pressure is below 10 kPa / s and maintained for at least 15 seconds; and the difference between the operating speed and the surge speed. Run at 120 rpm or higher for at least 15 seconds.

[0177] If the vibration speed of compressor 11 is detected Reaching 0.8 mm / s or higher, exhaust pressure fluctuation value Reaching 12 kPa / s or higher, or the difference between the operating speed and the surge speed. If the speed drops below 50 rpm, the compressor 11 is determined to be in a protective shutdown state, and the compressor 11 is controlled to immediately or within 3 seconds to perform a shutdown action.

[0178] To ensure effective protection of compressor 11, this embodiment does not exit the protection shutdown process after it is triggered.

[0179] refer to Figure 9 As shown, this application also provides an air conditioning system, the similarities of which with the above embodiments will not be repeated, the difference being that the controller 2 can be configured as follows:

[0180] Obtain vibration velocity Exhaust pressure fluctuation value And the operating speed (step S100), determine the vibration velocity. Exhaust pressure fluctuation value And whether the operating speed reaches the surge prevention condition (step S210). If so, control the compressor 11 to perform the frequency limiting action (step S220).

[0181] After controlling compressor 11 to perform the frequency limiting action, if the vibration speed is determined... Exhaust pressure fluctuation value If the operating speed meets the normal operating conditions and continues for at least the first preset time, that is, the surge prevention exit condition is met (step S230), then the compressor 11 is controlled to cancel the execution of the frequency limiting action (step S240).

[0182] It should be noted that the first preset duration can be flexibly set according to the air conditioning system capacity, the inertial characteristics of compressor 11, and the target application scenario, typically ranging from 10 to 60 seconds. The controller can implement this judgment using a timer module or software counting logic, or it can integrate an adaptive exit strategy based on historical trend analysis.

[0183] Based on the above configuration, parameter stability is ensured by a preset first duration condition, avoiding frequent switching due to instantaneous fluctuations and improving the robustness of the control logic.

[0184] This application determines and controls the compressor 11 to enter a limited frequency increase state based on surge prevention conditions. When all parameters return to the set normal operating range and remain stable for at least a first preset duration, it is considered that the compressor has stably recovered from the surge risk. At this point, the controller issues a defrost command, canceling the limited frequency increase action and allowing the compressor 11 to resume speed regulation according to load requirements, achieving a complete closed-loop regulation of "controlled entry—automatic exit." It supports automatic identification and recovery, possessing intelligent and adaptive advantages, and is particularly suitable for complex operating environments with frequent load changes, further ensuring the efficient and stable operation of the compressor 11 and extending its service life.

[0185] refer to Figure 10 As shown, controller 2 is also configured as follows:

[0186] Determine vibration velocity Exhaust pressure fluctuation value And whether the operating speed reaches the surge avoidance condition (step S310). If so, control the compressor 11 to perform forced frequency reduction action (step S320).

[0187] After the compressor 11 performs a forced frequency reduction action, if the vibration speed is determined... Exhaust pressure fluctuation value If the operating speed meets the surge avoidance exit condition (step S330), then control the compressor 11 to cancel the forced frequency reduction action (step S340).

[0188] Specifically, the surge avoidance exit condition is: vibration velocity. Exhaust pressure fluctuation value is below the surge velocity threshold and lasts for at least the second preset duration. The operating speed is below the surge pressure threshold and lasts for at least the second preset duration, and the difference between the operating speed and the surge speed is... The speed difference is higher than the surge speed difference and lasts for at least the second preset duration.

[0189] Based on the above configuration, this application also implements closed-loop control for surge avoidance, significantly improving system operating efficiency, energy-saving performance, and long-term operational safety and stability. When the system is in surge avoidance mode and compressor 11 is performing forced frequency reduction, the controller continuously monitors the vibration velocity. Exhaust pressure fluctuation value and difference .

[0190] If the surge avoidance exit condition is met, it is considered that the compressor 11 has escaped the surge risk, and a command is issued to release the forced frequency reduction action, allowing the compressor 11 to resume normal variable frequency speed regulation, thereby completing the adaptive transition from the risk state to the normal operating state.

[0191] The surge avoidance exit condition requires three independent parameters to be stable simultaneously, which greatly improves the reliability of the system's surge risk assessment.

[0192] By setting a second preset duration, the compressor 11 is guaranteed to truly return to a stable state, eliminating misjudgments caused by short-term interference or data fluctuations, ensuring the continuous stability of parameters, and improving the control accuracy and system robustness during the compressor 11's operating state transition process.

[0193] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

[0194] For ease of explanation, the above description has been provided in conjunction with specific embodiments. However, the above exemplary discussion is not intended to be exhaustive or to limit the embodiments to the specific forms disclosed above. Various modifications and variations can be obtained based on the above teachings. The selection and description of the above embodiments are for the purpose of better explaining the principles and practical applications, thereby enabling those skilled in the art to better utilize the described embodiments and various different variations of embodiments suitable for specific use considerations.

Claims

1. An air conditioning system, characterized in that, include: A chiller unit consists of a compressor, condenser, expansion valve, and evaporator connected in series via pipelines. The compressor is used to compress low-temperature, low-pressure refrigerant gas into high-temperature, high-pressure refrigerant gas and discharge it to the condenser. A vibration velocity acquisition module, fixed to the compressor housing, is used to monitor the vibration velocity of the housing. The vibration velocity acquisition module includes: The first vibration velocity sensor and the second vibration velocity sensor are mounted on the housing along the axial direction of the compressor and are used to acquire the first vibration velocity signal and the second vibration velocity signal. The third and fourth vibration velocity sensors are arranged radially on the compressor housing to acquire the third and fourth vibration velocity signals. A pressure sensor is installed at the exhaust port of the compressor to monitor the exhaust pressure of the compressor. The controller is electrically connected to the compressor, the vibration velocity acquisition module, and the pressure sensor. The controller is configured to: The compressor's operating speed, the casing vibration speed, and the exhaust pressure are obtained. Based on the casing vibration speed and the exhaust pressure, the compressor's vibration speed and exhaust pressure fluctuation values ​​are determined according to the first logic. It is then determined whether the compressor's vibration speed, exhaust pressure fluctuation values, and operating speed meet the normal operating conditions, surge prevention conditions, surge avoidance conditions, or protection shutdown conditions. If the surge prevention conditions are met, the compressor will be controlled to perform the corresponding frequency limiting action; If the surge avoidance condition is met, the compressor will be controlled to perform the corresponding forced frequency reduction action; If the protection shutdown conditions are met, the compressor will be controlled to perform the corresponding shutdown action; If normal operating conditions are met, the compressor will be controlled to operate normally. The normal operating conditions are configured as follows: The compressor's vibration speed is lower than the normal vibration speed threshold, the discharge pressure fluctuation value is lower than the normal pressure threshold, and the difference between the operating speed and the surge speed is higher than the normal speed difference. The surge prevention condition is met if any of the following conditions are met: The compressor's vibration velocity reaches or exceeds the normal vibration velocity threshold but is below the surge vibration velocity threshold; The exhaust pressure fluctuation value reaches above the normal pressure threshold but is below the surge pressure threshold; The difference between the operating speed and the surge speed is below the normal speed difference but higher than the surge speed difference; The surge avoidance condition is met if any of the following conditions are met: The compressor's vibration velocity reaches or exceeds the surge velocity threshold but is below the shutdown velocity threshold; The exhaust pressure fluctuation value reaches or exceeds the surge pressure threshold but is lower than the shutdown pressure threshold; The difference between the operating speed and the surge speed is below the surge speed difference but higher than the shutdown speed difference; The protection shutdown condition is met if any of the following conditions are met: The compressor's vibration speed reaches or exceeds the shutdown vibration speed threshold; The exhaust pressure fluctuation value reaches or exceeds the shutdown pressure threshold; The difference between the operating speed and the surge speed is below the difference between the stopping speed; The surge avoidance condition is met if any of the following conditions are met: The compressor's vibration velocity reaches or exceeds the surge velocity threshold but is below the shutdown velocity threshold; The exhaust pressure fluctuation value reaches or exceeds the surge pressure threshold but is lower than the shutdown pressure threshold; The difference between the operating speed and the surge speed is below the surge speed difference but higher than the shutdown speed difference; The first logic is configured as follows: Based on the first vibration velocity signal Second vibration velocity signal Third vibration velocity signal and the fourth vibration velocity signal Calculate the vibration velocity of the compressor ; The exhaust pressure fluctuation value is calculated based on the highest and lowest exhaust pressure values ​​within a preset period.

2. An air conditioning system, characterized in that, include: A chiller unit consists of a compressor, condenser, expansion valve, and evaporator connected in series via pipelines. The compressor is used to compress low-temperature, low-pressure refrigerant gas into high-temperature, high-pressure refrigerant gas and discharge it to the condenser. A vibration velocity acquisition module, fixed to the compressor housing, is used to monitor the vibration velocity of the housing. The vibration velocity acquisition module includes: The first vibration velocity sensor and the second vibration velocity sensor are mounted on the housing along the axial direction of the compressor and are used to acquire the first vibration velocity signal and the second vibration velocity signal. The third and fourth vibration velocity sensors are arranged radially on the compressor housing to acquire the third and fourth vibration velocity signals. A pressure sensor is installed at the exhaust port of the compressor to monitor the exhaust pressure of the compressor. The controller is electrically connected to the compressor, the vibration velocity acquisition module, and the pressure sensor. The controller is configured to: The compressor's operating speed, the housing vibration speed, and the exhaust pressure are obtained. Based on the housing vibration speed and the exhaust pressure, the compressor's vibration speed and exhaust pressure fluctuation values ​​are determined according to the first logic. It is then determined whether the compressor's vibration speed, exhaust pressure fluctuation values, and operating speed meet the surge prevention conditions. If so, the compressor is controlled to perform frequency limiting. After controlling the compressor to perform the frequency limiting action, if it is determined that the compressor's vibration speed, exhaust pressure fluctuation value, and operating speed meet the conditions for normal operation and remain so for at least a first preset duration, then the compressor is controlled to cancel the frequency limiting action. The first logic is configured as follows: Based on the first vibration velocity signal Second vibration velocity signal Third vibration velocity signal and the fourth vibration velocity signal Calculate the vibration velocity of the compressor ; The exhaust pressure fluctuation value is calculated based on the highest and lowest exhaust pressure values ​​within a preset period. The surge prevention condition is met if any of the following conditions are met: The compressor's vibration velocity reaches or exceeds the normal vibration velocity threshold but is below the surge vibration velocity threshold; The exhaust pressure fluctuation value reaches above the normal pressure threshold but is below the surge pressure threshold; The difference between the operating speed and the surge speed is below the normal speed difference but higher than the surge speed difference; The normal operating conditions are configured as follows: The compressor's vibration speed is lower than the normal vibration speed threshold, the discharge pressure fluctuation value is lower than the normal pressure threshold, and the difference between the operating speed and the surge speed is higher than the normal speed difference.

3. The air conditioning system according to claim 2, characterized in that, The controller is also configured to: Determine whether the vibration speed, exhaust pressure fluctuation value and operating speed of the compressor meet the surge avoidance conditions. If so, control the compressor to perform a forced frequency reduction action. After the compressor performs a forced frequency reduction action, if it is determined that the compressor's vibration speed, exhaust pressure fluctuation value, and operating speed meet the surge avoidance exit conditions, then the compressor is controlled to cancel the forced frequency reduction action. The surge avoidance exit condition is as follows: The compressor's vibration velocity is below the surge velocity threshold and lasts for at least the second preset duration. The exhaust pressure fluctuation value is lower than the surge pressure threshold and lasts for at least the second preset duration, and The difference between the operating speed and the surge speed is higher than the surge speed difference and lasts for at least the second preset duration; The surge avoidance condition is met if any of the following conditions are met: The compressor's vibration velocity reaches or exceeds the surge velocity threshold but is below the shutdown velocity threshold; The exhaust pressure fluctuation value reaches or exceeds the surge pressure threshold but is lower than the shutdown pressure threshold; The difference between the operating speed and the surge speed is below the surge speed difference but higher than the shutdown speed difference.

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