Control method of electronic expansion valve refrigerating system

Abstract

The embodiment of the invention discloses a control method of an electronic expansion valve refrigerating system. The control method of the electronic expansion valve refrigerating system comprises the steps that electrical parameters of the refrigerating system and first operation parameters collected in multiple continuous sampling periods are obtained, and whether an electronic expansion valve is out of step or not is judged according to the first operation parameters of the multiple continuous sampling periods; if the electronic expansion valve is out of step, performing out-of-step adjustment on the electronic expansion valve according to the out-of-step adjustment strategy; and if the out-of-step adjustment of the electronic expansion valve fails, a third operation parameter of the refrigerating system is obtained, and the frequency of the compressor and the rotating speed of the condensate fan are adjusted according to the third operation parameter so that the refrigerating system can operate normally. Compared with the prior art, the scheme improves the real-time performance and efficiency of calibration and the operation stability of the refrigeration system.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of refrigeration, and in particular, to a control method for an electronic expansion valve refrigeration system. Background Art

[0002] In a refrigeration system, the opening degree of an electronic expansion valve is generally adjusted to maintain normal operation. However, due to factors such as mechanical resistance and electromagnetic interference, the electronic expansion valve is prone to out-of-step (the deviation between the actual opening degree and the target opening degree is inconsistent), which reduces the control accuracy of the refrigeration system and further leads to the imbalance of the refrigeration system. Summary of the Invention

[0003] The embodiments of the present invention provide a control method for an electronic expansion valve refrigeration system to improve the control accuracy of the refrigeration system and maintain the normal operation of the refrigeration system.

[0004] In a first aspect, the embodiments of the present invention provide a control method for an electronic expansion valve refrigeration system, and the control method for the electronic expansion valve refrigeration system includes:

[0005] Obtain the electrical parameters of the refrigeration system and the first operating parameters collected in multiple consecutive sampling periods, and determine whether the electronic expansion valve is out-of-step according to the first operating parameters and the electrical parameters in the multiple consecutive sampling periods;

[0006] If the electronic expansion valve is out-of-step, perform out-of-step adjustment on the electronic expansion valve according to the out-of-step adjustment strategy;

[0007] If the out-of-step adjustment of the electronic expansion valve fails, obtain the third operating parameter of the refrigeration system, and adjust the frequency of the compressor and the rotation speed of the condenser fan according to the third operating parameter to make the refrigeration system operate normally.

[0008] Optionally, the determining whether the electronic expansion valve is out-of-step according to the first operating parameters and the electrical parameters in the multiple consecutive sampling periods includes:

[0009] Determine the dynamic out-of-step judgment threshold for each sampling period according to the first operating parameter of each sampling period;

[0010] Determine the drive coil current ripple rate of the electronic expansion valve according to the electrical parameter;

[0011] Determine whether the electronic expansion valve is out-of-step according to the dynamic out-of-step judgment threshold and the drive coil current ripple rate for each sampling period.

[0012] Optionally, the first operating parameters include the cumulative operating duration of the compressor, the outlet water temperature of the evaporator, and the suction pressure of the evaporator;

[0013] The step of determining the dynamic out-of-step judgment threshold for each sampling period includes:

[0014] Determine the evaporation temperature of the evaporator for each sampling period according to the suction pressure of the evaporator in each sampling period;

[0015] Determine the temperature gradient of the evaporator for each sampling period according to the evaporation temperature of the evaporator and the outlet water temperature of the evaporator in each sampling period;

[0016] Determine the dynamic out-of-step judgment threshold according to the temperature gradient of the evaporator and the cumulative operation duration of the compressor for each sampling period.

[0017] Optionally, the electrical parameter includes the driving coil current waveform;

[0018] The step of determining the driving coil current ripple rate of the electronic expansion valve includes:

[0019] Determine the peak current, valley current and average current according to the driving coil current waveform;

[0020] Determine the driving coil current ripple rate according to the peak current, the valley current and the average current.

[0021] Optionally, the step of determining whether the electronic expansion valve is out of step according to the dynamic out-of-step judgment threshold and the driving coil current ripple rate for each sampling period includes:

[0022] If the dynamic out-of-step judgment thresholds of multiple consecutive sampling periods increase monotonically and the driving coil current ripple rate is greater than the set ripple rate, the electronic expansion valve is out of step; otherwise, the electronic expansion valve is not out of step.

[0023] Optionally, the step of performing out-of-step adjustment on the electronic expansion valve according to the out-of-step adjustment strategy includes:

[0024] Obtain the real-time first operating parameter collected by the refrigeration system in the current sampling period in real time, and determine the real-time dynamic out-of-step judgment threshold and the real-time evaporator temperature gradient according to the real-time first operating parameter in real time;

[0025] Perform a primary calibration drive on the electronic expansion valve according to the real-time dynamic out-of-step judgment threshold;

[0026] Monitor the change rate of the real-time evaporator temperature gradient, and judge whether the primary calibration drive of the electronic expansion valve is successful according to the change rate of the real-time evaporator temperature gradient;

[0027] If the primary calibration drive of the electronic expansion valve is successful, adjust the opening degree of the electronic expansion valve according to the real-time temperature and real-time pressure of the refrigeration system to enable the normal operation of the refrigeration system;

[0028] If the primary calibration drive of the electronic expansion valve fails, perform a secondary calibration drive on the electronic expansion valve according to the real-time dynamic out-of-step judgment threshold;

[0029] Monitor the change rate of the real-time evaporator temperature gradient, and determine whether the secondary calibration drive of the electronic expansion valve is successful according to the change rate of the real-time evaporator temperature gradient;

[0030] If the secondary calibration drive of the electronic expansion valve is successful, adjust the opening degree of the electronic expansion valve according to the real-time temperature and real-time pressure of the refrigeration system to enable the normal operation of the refrigeration system;

[0031] If the secondary calibration drive of the electronic expansion valve fails, the out-of-step adjustment of the electronic expansion valve fails.

[0032] Optionally, the performing a primary calibration drive on the electronic expansion valve according to the real-time dynamic out-of-step judgment threshold includes:

[0033] Determine a first reverse error elimination pulse and a first inertia compensation pulse according to the real-time dynamic out-of-step judgment threshold and a first adjustment coefficient;

[0034] Perform a primary calibration drive on the electronic expansion valve successively according to the first reverse error elimination pulse and the first inertia compensation pulse;

[0035] The performing a secondary calibration drive on the electronic expansion valve according to the real-time dynamic out-of-step judgment threshold includes:

[0036] Determine a second reverse error elimination pulse and a second inertia compensation pulse according to the real-time dynamic out-of-step judgment threshold and a second adjustment coefficient;

[0037] Perform a secondary calibration drive on the electronic expansion valve successively according to the second reverse error elimination pulse and the second inertia compensation pulse.

[0038] Optionally, the step of adjusting the frequency of the compressor and the rotational speed of the condenser fan according to the third operating parameter includes:

[0039] Determine the target frequency of the compressor and the target rotational speed of the condenser fan according to the third operating parameter;

[0040] Adjust the frequency of the compressor according to the target frequency;

[0041] Adjust the rotational speed of the condenser fan according to the target rotational speed.

[0042] Optionally, the third operating parameter includes the target evaporation pressure of the evaporator, the actual evaporation pressure of the evaporator, the basic frequency of the compressor, and the basic rotational speed of the condenser fan;

[0043] The step of determining the target frequency of the compressor and the target rotational speed of the condenser fan includes:

[0044] Determine the target frequency according to the target evaporation pressure of the evaporator, the actual evaporation pressure of the evaporator, and the basic frequency of the compressor;

[0045] Determine the target rotational speed according to the target frequency, the basic frequency of the compressor, and the basic rotational speed of the condenser fan.

[0046] Optionally, the control method of the electronic expansion valve refrigeration system further includes:

[0047] If the electronic expansion valve is not out of step, adjust the opening degree of the electronic expansion valve according to the real-time temperature and real-time pressure of the refrigeration system to enable the normal operation of the refrigeration system;

[0048] If the out-of-step adjustment of the electronic expansion valve is successful, adjust the opening degree of the electronic expansion valve according to the real-time temperature and real-time pressure of the refrigeration system to enable the normal operation of the refrigeration system.

[0049] In the embodiments of the present invention, by using the first operating parameters and electrical parameters in multiple consecutive sampling periods, it is possible to comprehensively judge the current flow regulation accuracy, response speed, stability, motor performance, mechanical component wear, and drive circuit failure of the electronic expansion valve, and then accurately determine whether the electronic expansion valve is out of step. In the case of the electronic expansion valve being out of step, perform dynamic out-of-step adjustment on the electronic expansion valve according to the out-of-step adjustment strategy, which can improve the real-time performance, efficiency of the out-of-step calibration of the electronic expansion valve, and the stability of the operation of the refrigeration system. In the case of the failure of the out-of-step adjustment of the electronic expansion valve, the third operating parameter of the refrigeration system can be obtained, and the frequency of the compressor and the rotational speed of the condenser fan can be adjusted according to the third operating parameter to enable the normal operation of the refrigeration system; compared with the prior art of setting a double-valve structure to ensure the normal operation of the refrigeration system, this solution can reduce the dependence of the refrigeration system on the electronic expansion valve through software redundancy control of the compressor and the condenser fan, reduce the design cost of the refrigeration system, and reduce the design volume of the refrigeration system. Description of the Drawings

[0050] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained according to these drawings.

[0051] Figure 1 Schematic structural diagram of an electronic expansion valve refrigeration system provided by the prior art;

[0052] Figure 2 Schematic flow chart of a control method for an electronic expansion valve refrigeration system provided by an embodiment of the present invention;

[0053] Figure 3 Schematic flow chart of steps for determining whether an electronic expansion valve is out of step according to first operating parameters and the electrical parameters in multiple consecutive sampling periods provided by an embodiment of the present invention;

[0054] Figure 4 Schematic flow chart of steps for determining a dynamic out-of-step judgment threshold for each sampling period provided by an embodiment of the present invention;

[0055] Figure 5 Schematic flow chart of steps for determining a drive coil current ripple rate of an electronic expansion valve provided by an embodiment of the present invention;

[0056] Figure 6 Schematic flow chart of steps for performing out-of-step adjustment on an electronic expansion valve according to an out-of-step adjustment strategy provided by an embodiment of the present invention;

[0057] Figure 7 Schematic flow chart of steps for adjusting the frequency of a compressor and the rotational speed of a condenser fan according to a third operating parameter provided by an embodiment of the present invention. Detailed implementation manners

[0058] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0059] It should be noted that the terms "first", "second", etc. in the description, claims and above-mentioned drawings of the present invention are used to distinguish similar objects and do not necessarily have to be used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances so that the embodiments of the present invention described here can be implemented in an order different from those illustrated or described here. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0060] Figure 1 FIG. is a schematic structural diagram of an electronic expansion valve refrigeration system provided for the prior art, as Figure 1 shown. The electronic expansion valve refrigeration system includes an electronic expansion valve, an evaporator, a compressor, and a condenser.

[0061] Among them, the refrigeration system is based on the second law of thermodynamics, and the heat transfer is achieved by the refrigerant circulating in the circulation path composed of an electronic expansion valve, an evaporator, a compressor, and a condenser, so as to achieve the purpose of refrigeration. The following is a detailed introduction to the working principle of the refrigeration system:

[0062] Compression process: The compressor is one of the core components of the refrigeration system, which compresses the low-temperature and low-pressure refrigerant gas into a high-temperature and high-pressure gas. In this process, the compressor does work on the refrigerant, increasing the pressure and temperature of the refrigerant.

[0063] Condensation process: The high-temperature and high-pressure refrigerant gas generated by the compressor is transported to a condenser composed of a group of heat dissipation tubes or fins for heat exchange with the surrounding air or cooling water. At this time, the temperature of the refrigerant is higher than the temperature of the surrounding environment, and the heat will transfer from the refrigerant to the outside. The refrigerant gradually cools during the heat dissipation process and changes from a gaseous state to a liquid state, forming a high-temperature and high-pressure liquid refrigerant.

[0064] Throttling process: The high-temperature and high-pressure liquid refrigerant flows to the electronic expansion valve, and the electronic expansion valve restricts the flow of the refrigerant, causing the pressure of the refrigerant to suddenly decrease when passing through the electronic expansion valve. According to the principles of thermodynamics, the decrease in the pressure of the refrigerant will lead to a decrease in the boiling point of the refrigerant, causing the liquid refrigerant to start boiling and evaporating instantly when the pressure decreases, becoming a low-temperature and low-pressure gas-liquid mixed refrigerant.

[0065] Evaporation process: The refrigerant in the gas-liquid mixed state at low temperature and low pressure enters the evaporator. Inside the evaporator, the refrigerant liquid absorbs heat from the surrounding environment and rapidly evaporates at low temperature, reducing the temperature of the surrounding environment, thereby achieving the purpose of refrigeration. The low-temperature and low-pressure refrigerant gas after evaporation enters the compressor again, and a new cycle will start.

[0066] Through the above cycle process, the refrigeration system continuously transfers heat from a low-temperature object (such as the inside of a refrigerator, an air-conditioned room, etc.) to a high-temperature environment (such as outdoor air), achieving the refrigeration effect.

[0067] Figure 2 The following is a schematic flow chart of a control method for an electronic expansion valve refrigeration system provided by an embodiment of the present invention. As Figure 2 shown, the control method of the electronic expansion valve refrigeration system specifically includes the following steps:

[0068] S110. Obtain the electrical parameters of the refrigeration system and the first operating parameters collected in multiple consecutive sampling periods, and determine whether the electronic expansion valve is out of step according to the first operating parameters and electrical parameters in multiple consecutive sampling periods.

[0069] Among them, the electrical parameters of the refrigeration system include the current wave of the driving coil of the electronic expansion valve. According to the current wave of the driving coil of the electronic expansion valve, the current ripple rate of the driving coil can be determined, and the current ripple rate of the driving coil can reflect the flow regulation accuracy, response speed, and stability of the electronic expansion valve. Thus, by obtaining the electrical parameters of the refrigeration system, the current flow regulation accuracy, response speed, and stability of the electronic expansion valve can be determined.

[0070] The first operating parameters include the cumulative operating duration of the compressor, the outlet water temperature of the evaporator, and the suction pressure of the evaporator. Among them, according to the cumulative operating duration of the compressor, the outlet water temperature of the evaporator, and the suction pressure of the evaporator, a dynamic out-of-step judgment threshold can be determined, and the change of the dynamic out-of-step judgment threshold can reflect the motor performance of the electronic expansion valve, the wear condition of mechanical components, and the fault condition of the drive circuit. Thus, by obtaining the first operating parameters collected in multiple consecutive sampling periods, the motor performance of the electronic expansion valve, the wear condition of mechanical components, and the fault condition of the drive circuit can be determined.

[0071] In summary, by comprehensively judging the current flow regulation accuracy, response speed, stability, motor performance, mechanical component wear condition, and drive circuit fault condition of the electronic expansion valve according to the first operating parameters and electrical parameters in multiple consecutive sampling periods, the operating condition of the electronic expansion valve can be accurately confirmed, and thus it can be accurately determined whether the electronic expansion valve is out of step, so as to timely adjust the control of the refrigeration system according to the out-of-step condition of the electronic expansion valve and improve the control accuracy of the refrigeration system.

[0072] S120. If the electronic expansion valve is out of step, perform out-of-step adjustment on the electronic expansion valve according to the out-of-step adjustment strategy.

[0073] Among them, in the case where the electronic expansion valve is out of step, it is necessary to promptly perform dynamic out-of-step adjustment on the electronic expansion valve, that is, dynamically adjust the opening degree of the electronic expansion valve during the operation of the refrigeration system. The out-of-step adjustment strategy is out-of-step compensation control based on the out-of-step situation of the electronic expansion valve. It determines the reverse cancellation pulse according to the dynamic out-of-step judgment threshold of the electronic expansion valve to drive the valve needle of the electronic expansion valve to move to the target position, so as to eliminate the position deviation accumulated by historical out-of-step. When driving the valve needle of the electronic expansion valve to move to the target position, a certain displacement will be generated due to the running inertia of the valve needle. The inertia compensation pulse can be determined according to the dynamic out-of-step judgment threshold of the electronic expansion valve to compensate (eliminate) the displacement generated by the movement inertia of the valve needle, so as to ensure that the actual opening degree of the electronic expansion valve moves to the target position.

[0074] This solution performs dynamic out-of-step adjustment on the electronic expansion valve according to the out-of-step adjustment strategy. Compared with the prior art that requires out-of-step calibration adjustment strategy in the shutdown state of the refrigeration system, it improves the real-time performance, efficiency and stability of the refrigeration system operation.

[0075] S130. If the out-of-step adjustment of the electronic expansion valve fails, obtain the third operating parameter of the refrigeration system, and adjust the frequency of the compressor and the rotational speed of the condenser fan according to the third operating parameter to make the refrigeration system operate normally.

[0076] Among them, in the case where the electronic expansion valve is out of step, the evaporation pressure can be maintained at the target value by redundant control adjustment of the compressor and the condenser fan, compensating for the flow loss, so as to maintain the energy efficiency of the refrigeration system, that is, to make the refrigeration system operate normally.

[0077] Specifically, the third operating parameter includes the target evaporation pressure of the evaporator, the actual evaporation pressure of the evaporator, the base frequency of the compressor, and the base rotational speed of the condenser fan. According to the target evaporation pressure of the evaporator, the actual evaporation pressure of the evaporator, and the base frequency of the compressor, the target frequency at which the compressor can maintain the evaporation pressure at the target value can be determined; according to the target frequency of the compressor, the base frequency of the compressor, and the base rotational speed of the condenser fan, the target rotational speed at which the condenser fan can compensate for the flow loss can be determined.

[0078] In the case where the electronic expansion valve is out of step, this solution maintains the normal operation of the system through software redundant control of the compressor and the condenser fan. Compared with the prior art that sets a double-valve structure to ensure the normal operation of the refrigeration system, it reduces the dependence of the refrigeration system on the electronic expansion valve, reduces the design cost of the refrigeration system, and reduces the design volume of the refrigeration system.

[0079] Based on the above embodiments, optionally, Figure 3It is a schematic flowchart of a step for determining whether an electronic expansion valve is out of step according to the first operating parameters and the electrical parameters in multiple consecutive sampling periods provided by an embodiment of the present invention. As Figure 3 shown, the step of determining whether the electronic expansion valve is out of step according to the first operating parameters and the electrical parameters in multiple consecutive sampling periods is described as follows:

[0080] S210. Determine the dynamic out-of-step judgment threshold for each sampling period according to the first operating parameter of each sampling period.

[0081] Among them, the first operating parameters include the cumulative operating duration of the compressor, the outlet water temperature of the evaporator, and the suction pressure of the evaporator. Among them, the dynamic out-of-step judgment threshold can be determined according to the cumulative operating duration of the compressor, the outlet water temperature of the evaporator, and the suction pressure of the evaporator. The change of the dynamic out-of-step judgment threshold can reflect the motor performance of the electronic expansion valve, the wear condition of mechanical components, and the fault condition of the drive circuit.

[0082] S220. Determine the current ripple rate of the drive coil of the electronic expansion valve according to the electrical parameter.

[0083] Among them, the electrical parameter of the refrigeration system includes the current waveform of the drive coil. The current ripple rate of the drive coil can be determined according to the current waveform of the drive coil of the electronic expansion valve. The current ripple rate of the drive coil can reflect the flow regulation accuracy, response speed, and stability of the electronic expansion valve.

[0084] Specifically, the electronic expansion valve adjusts the valve opening by controlling the current of the drive coil, and then controls the refrigerant flow rate. If the current ripple rate of the drive coil is small, it means that the stability of the current is high, the control of the valve opening is more accurate, and more precise refrigerant flow regulation can be achieved, making the superheat control of the refrigeration system more stable, thereby improving the regulation accuracy of the refrigeration system.

[0085] The current ripple rate of the drive coil can also reflect the response speed of the electronic expansion valve to a certain extent. When the refrigeration system needs to quickly adjust the refrigerant flow rate, such as when the load of the refrigeration system suddenly changes, the drive coil current needs to quickly respond to change the opening of the electronic expansion valve. If the current ripple rate of the drive coil is high, it means that there are large fluctuations in the current change process, which will affect the response speed of the electronic expansion valve, resulting in insufficiently rapid adjustment of the valve opening and inability to meet the refrigerant flow rate requirements of the refrigeration system in time. On the contrary, a low current ripple rate of the drive coil is beneficial for the electronic expansion valve to quickly and accurately respond to system changes, enabling the refrigeration system to adapt to different working conditions faster.

[0086] In addition, a stable driving coil current is the basis for the stable operation of the electronic expansion valve. If the driving coil current ripple rate is too high, the magnetic field generated by the driving coil will be unstable, which will cause the valve to vibrate or operate unstably. A too-high driving coil current ripple rate will affect the stability of the refrigerant flow rate, and may also cause additional wear to the mechanical components of the electronic expansion valve, reducing its service life. A lower driving coil current ripple rate helps to ensure that the electronic expansion valve can stably control the valve opening under different operating conditions, provide a stable refrigerant flow rate for the refrigeration system, and maintain the stable operation of the system.

[0087] S230. Determine whether the electronic expansion valve is out of step according to the dynamic out-of-step judgment threshold and the driving coil current ripple rate in each sampling period.

[0088] Among them, when the motor performance of the electronic expansion valve deteriorates, mechanical components are worn, mechanical components are stuck, or a driving circuit failure occurs, etc., it will cause the electronic expansion valve to be out of step. In order to maintain the normal operation of the motor, the refrigeration system will gradually increase the dynamic out-of-step judgment threshold. Therefore, the increasing or decreasing trend of the dynamic out-of-step judgment threshold can be confirmed through the dynamic out-of-step judgment threshold in each sampling period, indirectly reflecting the operating condition of the electronic expansion valve.

[0089] When the electronic expansion valve is out of step, it will cause the flow regulation accuracy of the electronic expansion valve to decrease, the response speed to slow down, and the stability of the refrigerant flow rate to deteriorate. During the adjustment process of the electronic expansion valve, there will be large fluctuations in the current of the driving coil, which will lead to an increase in the driving coil current ripple rate. Therefore, the flow regulation accuracy, response speed, and stability of the electronic expansion valve can be confirmed through the driving coil current ripple rate, thereby indirectly reflecting the operating condition of the electronic expansion valve.

[0090] In summary, based on the operating condition of the electronic expansion valve confirmed by the dynamic out-of-step judgment threshold in each sampling period, combined with the operating condition of the electronic expansion valve confirmed by the driving coil current ripple rate, it is possible to accurately judge whether the electronic expansion valve is out of step.

[0091] Among them, the specific process of the step of determining whether the electronic expansion valve is out of step according to the dynamic out-of-step judgment threshold and the driving coil current ripple rate in each sampling period is further elaborated:

[0092] If the dynamic out-of-step judgment thresholds in multiple consecutive sampling periods are monotonically increasing and the driving coil current ripple rate is greater than the set ripple rate, the electronic expansion valve is out of step; otherwise, the electronic expansion valve is not out of step.

[0093] Among them, in the case of the electronic expansion valve being out of step, in order to maintain the normal operation of the electronic expansion valve motor, the refrigeration system will gradually increase the dynamic out-of-step judgment threshold. During the adjustment process of the electronic expansion valve valve, there will be large fluctuations in the current of the drive coil. The ripple rate is set to a preset value, and the set ripple rate is the maximum value that the current ripple rate of the drive coil reaches when the electronic expansion valve is not out of step.

[0094] Based on the above embodiments, optionally, Figure 4 This is a schematic flowchart of the steps for determining the dynamic out-of-step judgment threshold for each sampling period provided by the embodiments of the present invention. As Figure 4 shown, the steps for determining the dynamic out-of-step judgment threshold for each sampling period are described as follows:

[0095] S310. Determine the evaporation temperature of the evaporator for each sampling period according to the suction pressure of the evaporator for each sampling period.

[0096] Among them, according to the refrigerant type and the suction pressure of the evaporator for each sampling period, look up the evaporator suction pressure-evaporation temperature chart representing the saturation temperature (evaporation temperature of the evaporator) of the refrigerant at different pressures, so as to determine the evaporation temperature of the evaporator for each sampling period. The evaporator suction pressure-evaporation temperature chart usually has the evaporator suction pressure as the abscissa and the evaporation temperature of the evaporator as the ordinate.

[0097] S320. Determine the evaporator temperature gradient for each sampling period according to the evaporation temperature of the evaporator and the outlet water temperature of the evaporator for each sampling period.

[0098] Among them, the evaporator temperature gradient = the outlet water temperature of the evaporator - the evaporation temperature of the evaporator. Thus, according to the above formula, the evaporator temperature gradient for each sampling period is determined according to the evaporation temperature of the evaporator and the outlet water temperature of the evaporator for each sampling period.

[0099] S330. Determine the dynamic out-of-step judgment threshold according to the evaporator temperature gradient and the cumulative operation duration of the compressor for each sampling period.

[0100] Among them, the dynamic out-of-step judgment threshold △S = 8 + 0.3T HOUR + 0.5 * |△T|; 8 is the basic threshold constant term (the default tolerance in the new machine state of the electronic expansion valve), T HOUR is the cumulative operation duration of the compressor (which can reflect the degree of mechanical wear), 0.3 is the time weight coefficient (the incremental contribution of the operating time per hour to the dynamic out-of-step judgment threshold), △T is the evaporator temperature gradient (a quantitative index of the heat load state of the refrigeration system), and 0.5 is the temperature gradient weight coefficient (the incremental contribution of each °C temperature gradient to the dynamic out-of-step judgment threshold).

[0101] Based on the above embodiments, optionally, Figure 5 FIG. is a schematic flow chart of steps for determining the drive coil current ripple rate of an electronic expansion valve provided by an embodiment of the present invention. As Figure 5 shown, the steps for determining the drive coil current ripple rate of the electronic expansion valve are described as follows:

[0102] S410. Determine the peak current, valley current, and average current according to the drive coil current waveform.

[0103] Among them, the peak current is the maximum value of the drive coil current waveform, the valley current is the minimum value of the drive coil current waveform, and the average current is the average value of the drive coil current waveform.

[0104] S420. Determine the drive coil current ripple rate according to the peak current, valley current, and average current.

[0105] Among them, the drive coil current ripple rate refers to the ratio of the degree of current fluctuation to the average current in the drive coil. Drive coil current ripple rate = [(peak current - estimated current) / average current] * 100%.

[0106] Based on the above embodiments, optionally, Figure 6 FIG. is a schematic flow chart of steps for performing out-of-step adjustment on an electronic expansion valve according to an out-of-step adjustment strategy provided by an embodiment of the present invention. As Figure 6 shown, the steps for performing out-of-step adjustment on the electronic expansion valve according to the out-of-step adjustment strategy are described as follows:

[0107] S510. Real-time obtain the real-time first operating parameters collected by the refrigeration system in the current sampling period, and real-time determine the real-time dynamic out-of-step judgment threshold and the real-time evaporator temperature gradient according to the real-time first operating parameters.

[0108] Specifically, the real-time first operating parameters include the real-time cumulative operating duration of the compressor, the real-time outlet water temperature of the evaporator, and the real-time suction pressure of the evaporator. According to the refrigerant type and the real-time suction pressure of the evaporator collected in the current sampling period, look up the evaporator suction pressure-evaporator evaporation temperature chart representing the saturated temperature (real-time evaporator evaporation temperature) of the refrigerant at different pressures, so as to determine the real-time evaporator evaporation temperature collected in the current sampling period. According to the real-time evaporator evaporation temperature and the real-time outlet water temperature of the evaporator collected in the current sampling period, the evaporator temperature gradient of each sampling period can be determined. Among them, the real-time evaporator temperature gradient = real-time outlet water temperature of the evaporator - real-time evaporator evaporation temperature.

[0109] The real-time dynamic out-of-step judgment threshold can be determined according to the real-time cumulative operating duration of the compressor, the real-time outlet water temperature of the evaporator, and the real-time evaporator temperature gradient. Specifically, the real-time dynamic out-of-step judgment threshold △S = 8 + 0.3THOUR1 +0.5 * |ΔT1|; 8 is the basic threshold constant term (the default tolerance in the new state of the electronic expansion valve), T HOUR1 is the cumulative operating duration of the real-time compressor (which can reflect the degree of mechanical wear), 0.3 is the time weight coefficient (the incremental contribution of the operating time per hour to the dynamic out-of-step judgment threshold), ΔT1 is the real-time evaporator temperature gradient (a quantitative index of the heat load state of the refrigeration system), and 0.5 is the temperature gradient weight coefficient (the incremental contribution of each °C temperature gradient to the dynamic out-of-step judgment threshold).

[0110] S520. Perform a calibration drive on the electronic expansion valve according to the real-time dynamic out-of-step judgment threshold.

[0111] Among them, according to the real-time dynamic out-of-step judgment threshold, a pulse signal for performing a calibration drive on the electronic expansion valve can be determined. The pulse signal for performing a calibration drive on the electronic expansion valve includes a first reverse error elimination pulse and a first inertia compensation pulse. The first reverse error elimination pulse can drive the valve needle of the electronic expansion valve to move to the target position to eliminate the position deviation accumulated by historical out-of-step. When driving the valve needle of the electronic expansion valve to move to the target position, a certain displacement will be generated due to operating inertia. The second inertia compensation pulse can compensate (eliminate) the displacement generated by the valve needle due to movement inertia to ensure that the actual opening of the electronic expansion valve moves to the target position.

[0112] Specifically, the steps of performing a calibration drive on the electronic expansion valve according to the real-time dynamic out-of-step judgment threshold are elaborated:

[0113] ① Determine the first reverse error elimination pulse and the first inertia compensation pulse according to the real-time dynamic out-of-step judgment threshold and the first adjustment coefficient.

[0114] Among them, according to the real-time dynamic out-of-step judgment threshold, the direction in which the valve needle of the electronic expansion valve is away from the target position can be determined, so as to determine the moving direction of the first reverse error elimination pulse for eliminating the position deviation accumulated by historical out-of-step to drive the electronic expansion valve (i.e., the opposite direction of away from the target position), and the moving direction of the first reverse error elimination pulse for eliminating the position deviation accumulated by historical out-of-step to drive the electronic expansion valve (i.e., the opposite direction of away from the target position).

[0115] According to the real-time dynamic out-of-step judgment threshold, the number of pulses of the first reverse error elimination pulse can be determined. The number of pulses of the first reverse error elimination pulse = 1.2 * |real-time dynamic out-of-step judgment threshold|; the frequency of the first reverse error elimination pulse is preset, for example, set to 1.5KHZ; the duration of the first reverse error elimination pulse is preset, for example, set to 80MS. The duration of the first reverse error elimination pulse includes the application time and the delay time of the first reverse error elimination pulse.

[0116] The number of pulses of the first inertial compensation pulse can be determined according to the real-time dynamic out-of-step judgment threshold, and the number of pulses of the first inertial compensation pulse = 1.2 * |real-time dynamic out-of-step judgment threshold|; the frequency of the first reverse error elimination pulse is preset, for example, set to 2.5KHZ.

[0117] ② Calibrate and drive the electronic expansion valve once according to the first reverse error elimination pulse and the first inertial compensation pulse in sequence.

[0118] Specifically, first apply the first reverse error elimination pulse to the electronic expansion valve, and then apply the first inertial compensation pulse to the electronic expansion valve.

[0119] S530. Monitor the change rate of the real-time evaporator temperature gradient, and judge whether the one-time calibration drive of the electronic expansion valve is successful according to the change rate of the real-time evaporator temperature gradient.

[0120] Among them, the main function of the electronic expansion valve is to accurately control the refrigerant flow rate. When the electronic expansion valve is out of step, the opening of the electronic expansion valve cannot be accurately adjusted according to the target opening value, which will cause the refrigerant flow rate to be too large or too small. If the refrigerant flow rate is too large, the refrigerant in the evaporator cannot be fully evaporated, which will cause the temperature at the outlet of the evaporator to be too low, while the temperature at the inlet of the evaporator is relatively high, thus increasing the evaporator temperature gradient, and the change rate of the evaporator temperature gradient will also increase accordingly. On the contrary, if the refrigerant flow rate is too small, the refrigeration capacity of the evaporator is insufficient, which will cause the overall temperature of the evaporator to rise, resulting in an unstable change rate of the evaporator temperature gradient.

[0121] The specific method for judging whether the one-time calibration drive of the electronic expansion valve is successful according to the change rate of the real-time evaporator temperature gradient is: if the change rate of the real-time evaporator temperature gradient is less than or equal to the change rate threshold within the preset time, the one-time calibration drive of the electronic expansion valve is successful; otherwise, the one-time calibration drive of the electronic expansion valve fails.

[0122] Among them, both the preset time and the change rate threshold are preset values.

[0123] Exemplarily, if the change rate of the real-time evaporator temperature gradient ≤ 0.2℃ / MIN (change rate threshold) within 30 seconds (preset time), the one-time calibration drive of the electronic expansion valve is successful; otherwise, the one-time calibration drive of the electronic expansion valve fails.

[0124] S540. If the one-time calibration drive of the electronic expansion valve is successful, adjust the opening of the electronic expansion valve according to the real-time temperature and real-time pressure of the refrigeration system to make the refrigeration system operate normally.

[0125] Specifically, the real-time superheat of the refrigeration system can be determined based on the real-time temperature and real-time pressure. Among them, the corresponding saturation temperature is found through the pressure-saturation temperature conversion table of the refrigerant. The difference obtained by subtracting the saturation temperature from the real-time temperature is the real-time superheat. Based on the real-time superheat and the target superheat, the superheat difference can be determined. By performing PID calculation on the superheat difference, a signal for adjusting the opening of the electronic expansion valve is output, so that the valve needle of the electronic expansion valve moves to the target position, enabling the normal operation of the refrigeration system.

[0126] In addition, after the primary calibration drive of the electronic expansion valve is successful, a PWM wave with a frequency of 1KHZ and a duty cycle of 60% can be applied to the drive coil to generate a continuous electromagnetic force to suppress the micro-vibration of the valve needle.

[0127] S550: If the primary calibration drive of the electronic expansion valve fails, the electronic expansion valve is subjected to a secondary calibration drive according to the real-time dynamic out-of-step judgment threshold.

[0128] Among them, the pulse signal for the secondary calibration drive of the electronic expansion valve can be determined according to the real-time dynamic out-of-step judgment threshold. The pulse signal for the secondary calibration drive of the electronic expansion valve includes a second reverse error elimination pulse and a second inertia compensation pulse. The second reverse error elimination pulse can drive the valve needle of the electronic expansion valve to the target position to eliminate the position deviation accumulated by historical out-of-step. When driving the valve needle of the electronic expansion valve to the target position, a certain displacement will be generated due to the running inertia. The second inertia compensation pulse can compensate (eliminate) the displacement generated due to the movement inertia of the valve needle to ensure that the actual opening of the electronic expansion valve moves to the target position.

[0129] Specifically, the steps for the secondary calibration drive of the electronic expansion valve according to the real-time dynamic out-of-step judgment threshold are described as follows:

[0130] ① Determine the second reverse error elimination pulse and the second inertia compensation pulse according to the real-time dynamic out-of-step judgment threshold and the second adjustment coefficient.

[0131] Among them, according to the real-time dynamic out-of-step judgment threshold, the direction in which the valve needle of the electronic expansion valve is away from the target position can be determined, so as to determine the moving direction of the second reverse error elimination pulse for eliminating the position deviation accumulated by historical out-of-step to drive the electronic expansion valve (i.e., the opposite direction of moving away from the target position), and the moving direction of the second reverse error elimination pulse for eliminating the position deviation accumulated by historical out-of-step to drive the electronic expansion valve (i.e., the opposite direction of moving away from the target position).

[0132] According to the real-time dynamic out-of-step judgment threshold, the number of pulses of the second reverse error elimination pulse can be determined. The number of pulses of the second reverse error elimination pulse = 1.5 * |real-time dynamic out-of-step judgment threshold|; the frequency of the second reverse error elimination pulse is pre-set, for example, set to 1.5KHZ; the duration of the second reverse error elimination pulse is pre-set, for example, set to 80MS. The duration of the second reverse error elimination pulse includes the application time and the delay time of the second reverse error elimination pulse.

[0133] According to the real-time dynamic out-of-step judgment threshold, the number of pulses of the second inertia compensation pulse can be determined. The number of pulses of the second inertia compensation pulse = 1.5 * |real-time dynamic out-of-step judgment threshold|; the frequency of the second reverse error elimination pulse is pre-set, for example, set to 2.5KHZ.

[0134] ②Perform secondary calibration drive on the electronic expansion valve according to the second reverse error elimination pulse and the second inertia compensation pulse in sequence.

[0135] Specifically, first apply the second reverse error elimination pulse to the electronic expansion valve, and then apply the second inertia compensation pulse to the electronic expansion valve.

[0136] S560. Monitor the change rate of the real-time evaporator temperature gradient, and judge whether the secondary calibration drive of the electronic expansion valve is successful according to the change rate of the real-time evaporator temperature gradient.

[0137] Specifically, the specific method for judging whether the secondary calibration drive of the electronic expansion valve is successful according to the change rate of the real-time evaporator temperature gradient is the same as the specific method for judging whether the primary calibration drive of the electronic expansion valve is successful according to the change rate of the real-time evaporator temperature gradient, and will not be elaborated here.

[0138] S570. If the secondary calibration drive of the electronic expansion valve is successful, adjust the opening degree of the electronic expansion valve according to the real-time temperature and real-time pressure of the refrigeration system to make the refrigeration system operate normally.

[0139] Among them, after the secondary calibration drive of the electronic expansion valve is successful, a PWM wave with a frequency of 1KHZ and a duty cycle of 60% can be applied to the drive coil to generate a continuous electromagnetic force to suppress the micro-vibration of the valve needle.

[0140] S580. If the secondary calibration drive of the electronic expansion valve fails, the out-of-step adjustment of the electronic expansion valve fails.

[0141] Based on the above embodiments, optionally, Figure 7 This is a schematic flowchart of the steps for adjusting the frequency of the compressor and the rotational speed of the condenser fan according to the third operating parameter provided by the embodiment of the present invention. As Figure 7 shown, the steps for adjusting the frequency of the compressor and the rotational speed of the condenser fan according to the third operating parameter are described as follows:

[0142] S610. Determine the target frequency of the compressor and the target speed of the condenser fan according to the third operating parameter.

[0143] Among them, the third operating parameter includes the target evaporation pressure of the evaporator, the actual evaporation pressure of the evaporator, the basic frequency of the compressor, and the basic speed of the condenser fan.

[0144] Elaborate on the steps of determining the target frequency of the compressor and the target speed of the condenser fan:

[0145] ① Determine the target frequency according to the target evaporation pressure of the evaporator, the actual evaporation pressure of the evaporator, and the basic frequency of the compressor.

[0146] Among them, the target frequency = the basic frequency of the compressor + the compressor frequency adjustment proportional coefficient * (the target evaporation pressure of the evaporator - the actual evaporation pressure of the evaporator); the compressor frequency adjustment proportional coefficient represents the adjustment intensity of the compressor frequency with the change of the evaporator pressure deviation.

[0147] Exemplarily, the target evaporation pressure of the evaporator is 5.0 MPA, the actual evaporation pressure of the evaporator is 4.6 MPA, the basic frequency of the compressor is 50 HZ, and the compressor frequency adjustment proportional coefficient is 2.5 HZ / MPA; the target frequency = 50 + 2.5(5.0 - 4.6) = 51 HZ. At this time, the compressor frequency is increased from 50 HZ to 51 HZ, so that the refrigerant mass flow rate increases, and the evaporation pressure of the evaporator gradually rises close to the target value (such as 4.8 MPA), which can avoid triggering the low-pressure protection of the evaporator.

[0148] This solution increases the refrigerant circulation volume by increasing the compressor frequency, alleviates the influence of insufficient expansion valve opening, compensates for the flow loss, stabilizes the evaporator pressure, and prevents the evaporator from freezing or shutting down due to too low pressure.

[0149] ② Determine the target speed according to the target frequency, the basic frequency of the compressor, and the basic speed of the condenser fan.

[0150] Among them, the target speed = the basic speed of the condenser fan - 0.15 * (the target frequency - the basic frequency of the compressor) * 1000. The minimum speed limit of the condenser fan is 30% of the basic speed of the condenser fan.

[0151] Exemplarily, the basic speed of the condenser fan is 1000 RPM, the compressor frequency has been increased to the target frequency of 51 HZ, and the basic frequency of the compressor is 50 HZ; the target speed = 1000 - 0.15(51 - 50)1000 = 850 RPM. The speed of the condenser fan is reduced from 1000 RPM to 850 RPM, so that the heat dissipation capacity of the condenser decreases; the condensation pressure (P COND) rises from 3.0 MPA to 3.2 MPA, and the temperature of the condenser increases.

[0152] This solution improves the condensation stage pressure by reducing the rotational speed of the condensation fan, reduces the compression ratio of the compressor, avoids compressor overload, and balances the compression ratio of the refrigeration system; the increase in the pressure of the condensation fan can increase the subcooling degree of the refrigerant before the expansion valve, partially compensating for the efficiency loss caused by insufficient flow rate, and thus enhancing the subcooling degree of the refrigerant.

[0153] S620. Adjust the frequency of the compressor according to the target frequency.

[0154] Among them, adjust the frequency of the compressor to the target frequency.

[0155] S630. Adjust the rotational speed of the condensation fan according to the target rotational speed.

[0156] Among them, adjust the rotational speed of the condensation fan to the target rotational speed.

[0157] Based on the above embodiments, optionally, the control method of the electronic expansion valve refrigeration system further includes:

[0158] If the electronic expansion valve is not out of step, adjust the opening of the electronic expansion valve according to the real-time temperature and real-time pressure of the refrigeration system to enable the normal operation of the refrigeration system.

[0159] If the out-of-step adjustment of the electronic expansion valve is successful, adjust the opening of the electronic expansion valve according to the real-time temperature and real-time pressure of the refrigeration system to enable the normal operation of the refrigeration system.

[0160] Specifically, the real-time superheat degree of the refrigeration system can be determined according to the real-time temperature and real-time pressure. Among them, by referring to the pressure-saturation temperature table of the refrigerant, the corresponding saturation temperature is found. Subtract the saturation temperature from the real-time temperature, and the obtained difference is the real-time superheat degree. According to the real-time superheat degree and the target superheat degree, the superheat degree difference can be determined. By performing PID calculation on the superheat degree difference, a signal for adjusting the opening of the electronic expansion valve is output, so that the valve needle of the electronic expansion valve moves to the target position to enable the normal operation of the refrigeration system.

[0161] It should be understood that various forms of the flow shown above can be used, reordering, adding or deleting steps. For example, the steps recorded in the present invention can be executed in parallel, sequentially, or in a different order, as long as the desired results of the technical solution of the present invention can be achieved, and no limitation is made herein.

[0162] The above specific implementation manners do not constitute a limitation to the protection scope of the present invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A control method for an electronic expansion valve refrigeration system, characterized in that: include: Acquire electrical parameters of the refrigeration system and first operating parameters collected in multiple continuous sampling periods, and determine whether the electronic expansion valve is out of step according to the first operating parameters and the electrical parameters in the multiple continuous sampling periods; If the electronic expansion valve is out of step, the electronic expansion valve is adjusted according to the out of step adjustment strategy; If the out-of-step adjustment of the electronic expansion valve fails, the third operating parameter of the refrigeration system is obtained, and the frequency of the compressor and the speed of the condensing fan are adjusted according to the third operating parameter to enable the refrigeration system to operate normally.

2. The control method of the electronic expansion valve refrigeration system according to claim 1, characterized in that: The determining whether the electronic expansion valve is out of step according to the first operating parameter and the electrical parameter of a plurality of continuous sampling periods includes: Determining a dynamic out-of-step judgment threshold for each sampling period according to the first operating parameter of each sampling period; Determining a current ripple rate of a drive coil of the electronic expansion valve according to the electrical parameters; Whether the electronic expansion valve is out of step is determined according to the dynamic out-of-step judgment threshold and the drive coil current ripple rate in each sampling period.

3. The control method of the electronic expansion valve refrigeration system according to claim 2, characterized in that: The first operating parameters include the cumulative operating time of the compressor, the evaporator outlet water temperature and the evaporator suction pressure; The step of determining the dynamic out-of-step judgment threshold of each sampling period includes: Determining the evaporation temperature of the evaporator in each sampling period according to the suction pressure of the evaporator in each sampling period; Determining the evaporator temperature gradient of each sampling period according to the evaporation temperature of the evaporator and the evaporator outlet water temperature of each sampling period; The dynamic out-of-step judgment threshold is determined according to the evaporator temperature gradient and the accumulated running time of the compressor in each sampling period.

4. The control method of the electronic expansion valve refrigeration system according to claim 3, characterized in that: The electrical parameters include a drive coil current waveform; The step of determining the current ripple rate of the driving coil of the electronic expansion valve comprises: Determine the peak current, the valley current and the average current according to the driving coil current waveform; The driving coil current ripple rate is determined according to the peak current, the valley current and the average current.

5. The control method of the electronic expansion valve refrigeration system according to claim 4, characterized in that: The step of determining whether the electronic expansion valve is out of step according to the dynamic out-of-step judgment threshold value and the current ripple rate of the drive coil in each sampling period includes: If the dynamic out-of-step judgment threshold value of multiple consecutive sampling cycles increases monotonically and the drive coil current ripple rate is greater than the set ripple rate, the electronic expansion valve is out of step; otherwise, the electronic expansion valve is not out of step.

6. The control method of the electronic expansion valve refrigeration system according to claim 1, characterized in that: The step of performing out-of-step adjustment on the electronic expansion valve according to the out-of-step adjustment strategy comprises: Acquire in real time a real-time first operating parameter of the refrigeration system collected in a current sampling period, and determine in real time a real-time dynamic out-of-step judgment threshold and a real-time evaporator temperature gradient according to the real-time first operating parameter; Performing a calibration drive on the electronic expansion valve according to the real-time dynamic out-of-step judgment threshold; Monitoring the change rate of the real-time evaporator temperature gradient, and judging whether a calibration drive of the electronic expansion valve is successful according to the change rate of the real-time evaporator temperature gradient; If the electronic expansion valve is successfully calibrated and driven once, the opening of the electronic expansion valve is adjusted according to the real-time temperature and real-time pressure of the refrigeration system to enable the refrigeration system to operate normally; If the electronic expansion valve fails to be calibrated and driven once, the electronic expansion valve is calibrated and driven twice according to the real-time dynamic out-of-step judgment threshold; monitoring the change rate of the real-time evaporator temperature gradient, and judging whether the secondary calibration drive of the electronic expansion valve is successful according to the change rate of the real-time evaporator temperature gradient; If the secondary calibration drive of the electronic expansion valve is successful, adjusting the opening of the electronic expansion valve according to the real-time temperature and real-time pressure of the refrigeration system so as to enable the normal operation of the refrigeration system; If the secondary calibration drive of the electronic expansion valve fails, the out-of-step adjustment of the electronic expansion valve fails.

7. The control method of the electronic expansion valve refrigeration system according to claim 6, characterized in that: The step of performing a calibration drive on the electronic expansion valve according to the real-time dynamic out-of-step judgment threshold comprises: Determine a first reverse error elimination pulse and a first inertia compensation pulse according to the real-time dynamic out-of-step judgment threshold and the first adjustment coefficient; performing a calibration drive on the electronic expansion valve according to the first reverse difference elimination pulse and the first inertia compensation pulse in sequence; The performing secondary calibration driving on the electronic expansion valve according to the real-time dynamic out-of-step judgment threshold comprises: Determine a second reverse error elimination pulse and a second inertia compensation pulse according to the real-time dynamic out-of-step judgment threshold and the second adjustment coefficient; The electronic expansion valve is driven for a second calibration according to the second reverse difference elimination pulse and the second inertia compensation pulse in sequence.

8. The control method of the electronic expansion valve refrigeration system according to claim 1, characterized in that: The step of adjusting the frequency of the compressor and the speed of the condensing fan according to the third operating parameter comprises: Determining a target frequency of the compressor and a target speed of the condensing fan according to the third operating parameter; adjusting the frequency of the compressor according to the target frequency; The rotation speed of the condensing fan is adjusted according to the target rotation speed.

9. The control method of the electronic expansion valve refrigeration system according to claim 8, characterized in that: The third operating parameter includes the target evaporation pressure of the evaporator, the actual evaporation pressure of the evaporator, the basic frequency of the compressor and the basic speed of the condensing fan; The step of determining the target frequency of the compressor and the target speed of the condensing fan comprises: determining the target frequency according to the target evaporation pressure of the evaporator, the actual evaporation pressure of the evaporator and the basic frequency of the compressor; The target speed is determined according to the target frequency, the compressor base frequency and the condensing fan base speed.

10. The control method of the electronic expansion valve refrigeration system according to claim 1, characterized in that: Also includes: If the electronic expansion valve is not out of step, adjusting the opening of the electronic expansion valve according to the real-time temperature and real-time pressure of the refrigeration system to enable the refrigeration system to operate normally; If the out-of-step adjustment of the electronic expansion valve is successful, the opening of the electronic expansion valve is adjusted according to the real-time temperature and real-time pressure of the refrigeration system to enable the refrigeration system to operate normally.

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